Dental Erosion and Medical Conditions An Overview of Aetiology, Diagnosis and Management

PubMed Central

Paryag, A; Rafeek, R

2014-01-01

ABSTRACT Tooth wear or tooth surface loss is a normal physiological process and occurs throughout life but is considered pathological when the degree of destruction is excessive or the rate of loss is rapid, causing functional, aesthetic or sensitivity problems. The importance of tooth wear as a dental problem has been increasingly recognized. The findings of a study in Trinidad indicate that the prevalence of tooth wear in a Trinidadian population is comparable to the United Kingdom (UK) and, indeed, that the level of moderate and severe wear is nearly twice as high. The aetiology of tooth wear is attributed to four causes: erosion, attrition, abrasion and abfraction. Erosion is generally considered to be the most prevalent cause of tooth wear in the UK and Europe. Acids that cause dental erosion originate mainly from the diet or the stomach and, to a lesser extent, the environment. Underlying medical problems can contribute to influence the progress of tooth wear due to erosion and the patient may not be aware of these conditions. Moderate to severe tooth wear poses a significant clinical challenge to dental practitioners and may result in treatment that is more complex and costly to the patient, both in terms of finances and time spent in the dental chair. This paper provides an overview of aetiology and diagnosis of tooth wear, in particular tooth wear due to erosion, so that medical and dental practitioners may recognize tooth wear early, institute preventive measures and manage patients appropriately. PMID:25781289

Factors associated with tooth loss and prosthodontic status among Sudanese adults.

PubMed

Khalifa, Nadia; Allen, Patrick F; Abu-bakr, Neamat H; Abdel-Rahman, Manar E

2012-01-01

A study was conducted to determine the degree of tooth loss, factors influencing tooth loss, and the extent of prosthodontic rehabilitation in Sudanese adults (≥ 16 years old) attending outpatient clinics in Khartoum State. Pearson and multivariate analyses were used to examine the relationships between tooth loss and specific characteristics determined through interviews and clinical examinations. The mean number of missing teeth was 3.6 (SD, 4.9) and the prevalence of edentulism was 0.1%. The prevalence of tooth loss (missing at least one tooth) was 78%; 66.9% of tooth loss was due to caries, and 11.2% was attributable to other reasons. Prosthetic replacement of missing teeth was evident in 3%, whereas a need for prosthetic replacement was evident in 57%. Having < 20 teeth was associated with age, gender, and socioeconomic status; tooth loss due to caries was associated with age, tribe, frequency of tooth-brushing, and a low rate of dental consultation. Tooth loss due to other reasons was associated with age, tribe, education, periodontal pocketing, tobacco use, tooth wear, and prosthetic status. The results of the present study indicated that the major cause of tooth loss was dental caries, thus emphasizing the importance of a public prevention-based healthcare program. Replacement of missing teeth was uncommon in the study subjects, which may reflect lack of access to this type of oral healthcare.

Tooth loss patterns in older adults with special needs: a Minnesota cohort

PubMed Central

Chen, Xi; Clark, Jennifer J

2011-01-01

This study was conducted to detail tooth loss patterns in older adults with special needs. A total of 491 elderly subjects with special needs were retrospectively selected and followed during 10/1999-12/2006. Medical, dental, cognitive, and functional assessments were abstracted from dental records and used to predict risk of tooth loss. Tooth loss events were recorded for subjects during follow-up. Chi-squared tests were used to study the association between tooth loss and the selected risk factors. Logistic, poisson, and negative binomial regressions were developed to study tooth loss patterns. Overall, 27% of the subjects lost at least one tooth during follow-up. Fourteen subjects had tooth loss events per 100 person-years. Tooth loss pattern did not differ significantly among different special-needs subgroups (i.e. community-dwelling vs. long-term care, physically disabled vs. functionally independent). Special-needs subjects with three or more active dental conditions at arrival had more than twice the risk of losing teeth than those without any existing conditions. After adjusting other factors, the number of carious teeth or retained roots at arrival was a significant predictor of tooth loss for older adults with special needs (P=0.001). These findings indicate that appropriately managing active caries and associated conditions is important to prevent tooth loss for older adults with special needs. PMID:21449213

Selective removal of dental composite using a rapidly scanned carbon dioxide laser

NASA Astrophysics Data System (ADS)

Chan, Kenneth H.; Fried, Daniel

2011-03-01

Dental restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants or removing composite adhesives such as residual composite left after debonding orthodontic brackets. In this study a carbon dioxide laser operating at high laser pulse repetition rates integrated with a galvanometer based scanner was used to selectively remove composite from tooth surfaces. A diode array spectrometer was used to measure the plume emission after each laser pulse and determine if the ablated material was tooth mineral or composite. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. The laser was able to rapidly remove the composites rapidly from both surfaces with minimal damage to the underlying sound enamel.

Rapid and Selective Removal of Composite From Tooth Surfaces With a 9.3 μm CO2 Laser Using Spectral Feedback

PubMed Central

Chan, Kenneth H.; Hirasuna, Krista; Fried, Daniel

2015-01-01

Objective Dental composite restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants, or removing composite adhesives such as residual composite left after debonding orthodontic brackets. Methods In this study, a carbon dioxide laser operating at 9.3-μm with a pulse duration of 10–20-microsecond and a pulse repetition rate of ~200 Hz was integrated with a galvanometer based scanner and used to selectively remove composite from tooth surfaces. Spectra of the plume emission were acquired after each laser pulse and used to differentiate between the ablation of dental enamel or composite. Microthermocouples were used to monitor the temperature rise in the pulp chamber during composite removal. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser beam was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. Results The laser was able to rapidly remove composite from tooth buccal and occlusal surfaces with minimal damage to the underlying sound enamel and without excessive heat accumulation in the tooth. Conclusion This study demonstrated that composite can be selectively removed from tooth surfaces at clinically relevant rates using a CO2 laser operating at 9.3-μm with high pulse repetition rates with minimal heat deposition and damage to the underlying enamel. PMID:21956630

Rapid and selective removal of composite from tooth surfaces with a 9.3 µm CO2 laser using spectral feedback.

PubMed

Chan, Kenneth H; Hirasuna, Krista; Fried, Daniel

2011-09-01

Dental composite restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants, or removing composite adhesives such as residual composite left after debonding orthodontic brackets. In this study, a carbon dioxide laser operating at 9.3-µm with a pulse duration of 10-20-microsecond and a pulse repetition rate of ∼200 Hz was integrated with a galvanometer based scanner and used to selectively remove composite from tooth surfaces. Spectra of the plume emission were acquired after each laser pulse and used to differentiate between the ablation of dental enamel or composite. Microthermocouples were used to monitor the temperature rise in the pulp chamber during composite removal. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser beam was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. The laser was able to rapidly remove composite from tooth buccal and occlusal surfaces with minimal damage to the underlying sound enamel and without excessive heat accumulation in the tooth. This study demonstrated that composite can be selectively removed from tooth surfaces at clinically relevant rates using a CO(2) laser operating at 9.3-µm with high pulse repetition rates with minimal heat deposition and damage to the underlying enamel. Copyright © 2011 Wiley-Liss, Inc.

Minimum intervention dentistry and the management of tooth wear in general practice.

PubMed

Meyers, I A

2013-06-01

The incidence of tooth wear, or non-carious tooth surface loss (NCTSL), is increasing and oral rehabilitation of patients with non-carious tooth loss requires strategies that address all the factors relevant to the aetiology and pathogenesis of the condition. The multifactorial nature of tooth wear and the variability in its clinical presentation provides treatment challenges for the clinician and successful management must be more than just restoration. Management must include an appropriate mix of preventive and restorative strategies and an understanding that long-term restorative success is affected by the patient's oral environment, and how diet, lifestyle and medical status can modify this environment. Ultimately, the success of any restorative intervention is very dependent on the stability of the oral environment and the condition of the remaining tooth structure. Minimum intervention dentistry (MID) philosophies are ideally suited to tooth wear cases and an overall MID strategy involving diagnosis, recognition and control of predisposing factors, stabilization of the oral environment, remineralization and restoration of the tooth structure, and ongoing maintenance can be implemented. When restorative treatment is required, contemporary materials and techniques are available that can provide cost-effective and conservative restorative alternatives for patients unable to undergo the complex indirect restorative techniques that are both costly and time consuming to implement. These minimally invasive approaches are not only an economically viable solution, but can provide aesthetic and functional rehabilitation and maintain tooth structure as a precursor to more complex restorative options when required. © 2013 Australian Dental Association.

Surface modulation of dental hard tissues

NASA Astrophysics Data System (ADS)

Tantbirojn, Daranee

Tooth surfaces play a central role in the equilibrium of dental hard tissues, in which contrasting processes lead to loss or deposition of materials. The central interest of this Thesis was the modulation of tooth surfaces to control such equilibrium. Four specific studies were carried out to investigate different classes of surface modulating agents. These are: (1) Ionic modulation of the enamel surface to enhance stain removal . Dental stain is the most apparent form of tooth surface deposit. The nature of extrinsic stain in terms of spatial chemical composition was studied by using electron probe microanalysis. An ionic surface modulating agent, sodium tripolyphosphate (STPP), was evaluated. Image analysis methodologies were developed and the ability of STPP in stain removal was proved. (2) Thin film modulation with substantive polymeric coating and the effect on in vitro enamel de/re-mineralization . A novel polymeric coating that formed a thin film on the tooth surface was investigated for its inhibitory effect on artificial enamel caries, without interfering with the remineralization process. The preventive effect was distinct, but the mineral redeposition was questionable. (3) Thick film modulation with fluoride containing sealants and the effect on in vitro enamel and root caries development. Fluoride incorporated into resin material is an example of combining different classes of surface modulating agents to achieve an optimal outcome. A proper combination, such as in resin modified glass ionomer, showed in vitro caries inhibitory effect beyond the material boundary in both enamel and dentin. (4) Thick film modulation with dental adhesives and the determination of adhesion to dentin. Dentin adhesives modulate intracoronal tooth surfaces by enhancing adhesion to restorative materials. Conventional nominal bond tests were inadequate to determine the performance of current high strength adhesives. It was shown that interfacial fracture toughness test was more appropriate. In general, this Thesis evaluates diverse tooth surface modulations, for which several experimental methodologies had to be developed. These will be invaluable for the development of succeeding generations of surface modulating agents.

Erosive tooth wear: prevalence and severity in Swedish winetasters.

PubMed

Wiktorsson, A M; Zimmerman, M; Angmar-Månsson, B

1997-12-01

Full-time Swedish winetasters test on average 20-50 different wines, nearly 5 days a week. As the pH of wines ranges from 3.0 to 3.6, there is a potential risk for tooth erosion. The aims of this study were to document the prevalence and severity of tooth erosion in qualified winetasters in relation to number of years of winetasting, salivary flow rate, and buffer capacity. The subjects comprised all 19 qualified winetasters (7 women and 12 men, aged 29-64 years employed in Stockholm by Vin & Sprit AB, the state-owned company marketing wines and spirits. At intraoral examination, tooth surface loss was registered and documented by photography. Salivary flow rate and buffer capacity of unstimulated and stimulated saliva were measured. Data on occupational background and dental and medical histories were collected. Fourteen subjects had tooth erosion, the severity varying from mild to extreme, mainly on the labio-cervical surfaces of maxillary incisors and canines. The severity of the erosion tended to increase with years of occupational exposure. Caries activity in all subjects was low. 14 subjects had low unstimulated salivary flow rates. It was concluded that full-time winetasting is an occupation associated with increased risk for tooth erosion.

Automated ablation of dental composite using an IR pulsed laser coupled to a plume emission spectral feedback system.

PubMed

Jang, Andrew T; Chan, Kenneth H; Fried, Daniel

2017-01-28

Dental composites are used as restorative materials for filling cavities, shaping, and covering teeth for esthetic purposes, and as adhesives. Dentists spend more time replacing existing restorations that fail than they do placing new restorations. Tooth colored restorations are difficult to differentiate from the surrounding tooth structure making them challenging to remove without damaging healthy tooth structure. Previous studies have demonstrated that CO 2 lasers in conjunction with spectral feedback can be used to selectively remove composite from tooth surfaces. The purpose of this study is to assemble a system that is feasible for clinical use incorporating a spectral feedback system, a scanning system, articulating arm and a clinical handpiece and then evaluate the performance of that system on extracted teeth. In addition, the selectivity of composite removal was analyzed using a high-speed optical coherence tomography system that is suitable for clinical use. The system was capable of rapidly removing composite from small preparations on tooth occlusal surfaces with a mean loss of enamel of less than 20-μm.

Automated ablation of dental composite using an IR pulsed laser coupled to a plume emission spectral feedback system

NASA Astrophysics Data System (ADS)

Jang, Andrew T.; Chan, Kenneth H.; Fried, Daniel

2017-02-01

Dental composites are used as restorative materials for filling cavities, shaping, and covering teeth for esthetic purposes, and as adhesives. Dentists spend more time replacing existing restorations that fail than they do placing new restorations. Tooth colored restorations are difficult to differentiate from the surrounding tooth structure making them challenging to remove without damaging healthy tooth structure. Previous studies have demonstrated that CO2 lasers in conjunction with spectral feedback can be used to selectively remove composite from tooth surfaces. The purpose of this study is to assemble a system that is feasible for clinical use incorporating a spectral feedback system, a scanning system, articulating arm and a clinical handpiece and then evaluate the performance of that system on extracted teeth. In addition, the selectivity of composite removal was analyzed using a high-speed optical coherence tomography system that is suitable for clinical use. The system was capable of rapidly removing composite from small preparations on tooth occlusal surfaces with a mean loss of enamel of less than 20-μm.

Impact wear behavior of human tooth enamel under simulated chewing conditions.

PubMed

Zheng, Jing; Zeng, Yangyang; Wen, Jian; Zheng, Liang; Zhou, Zhongrong

2016-09-01

Previous studies mostly focused on the sliding wear behavior of human teeth, and little effort has been made so far to study the impact wear of human teeth. The objective of this study was to investigate the impact wear process and mechanism of human tooth enamel and the influence of water content within enamel. In this paper, the impact wear behaviors of fresh and dried human tooth enamel against SiC ceramic have been investigated using a specially designed impact test machine. Tests lasting up to 5×10(3), 5×10(4), 2.5×10(5), 5.5×10(5), 8×10(5) and 1×10(6) cycles were conducted, respectively. Results showed that for the fresh enamel, the surface damage was dominated by plastic deformation at the early stage of impact wear. Iridescent rings appeared around the impact mark as a result of the accumulation and spread of plastic deformation. As the impact wear progressed, delamination occurred on the surface of enamel, and thus the iridescent rings gradually disappeared. Wear loss increased rapidly with the increase of impact cycles. When a wear particle layer was formed on the enamel surface, the wear rate decreased. It was found that the surface hardness of enamel increased with the impact cycles, and no cracks appeared on the cross section of wear scar. Compared with the fresh enamel, the fracture toughness of dried enamel decreased, and thus there were microcracks appearing on the cross section of wear scar. More obvious delamination occurred on the worn surface of dried enamel, and no iridescent rings were observed. The wear loss of dried enamel was higher than that of fresh enamel. In summary, the impact wear behavior of sound human tooth enamel was metal-like to some degree, and no subsurface cracking occurred. The water content within enamel could increase its fracture toughness and protect the surface from impact wear. The wear mechanism of human tooth enamel is determined by its microstructure. Copyright © 2016 Elsevier Ltd. All rights reserved.

Graded changes in enamel component volumes resulted from a short tooth bleaching procedure.

PubMed

Ferreira, Artemisa Fernanda Moura; Perez, Flávia Maria de Moraes Ramos; Limeira Júnior, Francisco de Assis; de Moura, Mirella de Fátima Liberato; de Sousa, Frederico Barbosa

2016-05-01

To test the hypothesis that changes in enamel component volumes (mineral, organic, and water volumes, and permeability) are graded from outer to inner enamel after a short bleaching procedure. Extracted unerupted human third molars had half of their crowns bleached (single bleaching session, 3 × 15 min), and tooth shade changes in bleached parts were analyzed with a spectrophotometer. Ground sections were prepared, component volumes and permeability were quantified at histological points located at varying distances from the enamel surface (n=10 points/location), representing conditions before and after bleaching. Tooth shade changes were significant (p<0.001; 95% CI=-1/-8; power=99%), and most of the enamel layer was unaffected after bleaching, except at the outer layers. Multiple analysis of covariances revealed that most of the variance of the change in enamel composition after bleaching was explained by the combination of the set of types of component volume (in decreasing order of relevance: mineral loss, organic gain, water gain, and decrease in permeability) with the set of distances from the enamel surface (graded from the enamel surface inward) (canonical R(2)=0.97; p<0.0001; power>99%). Changes in enamel composition after a short bleaching procedure followed a gradient within component volumes (mineral loss>organic gain>water gain>decrease in permeability) and decreased from the enamel surface inward. Copyright © 2016 Elsevier Ltd. All rights reserved.

Aggravated loss of tooth structure.

PubMed

Barsby, M J

1989-09-01

Self-inflicted tooth modification other than ritual mutilation practised in some countries is a rare occurrence. The author reports a case of aggravated loss of tooth structure where a patient has contributed to loss of tooth structure by the novel method of adjusting his natural teeth with a 'knife'. Subsequent management of the case is discussed.

Periodontal profile classes predict periodontal disease progression and tooth loss.

PubMed

Morelli, Thiago; Moss, Kevin L; Preisser, John S; Beck, James D; Divaris, Kimon; Wu, Di; Offenbacher, Steven

2018-02-01

Current periodontal disease taxonomies have limited utility for predicting disease progression and tooth loss; in fact, tooth loss itself can undermine precise person-level periodontal disease classifications. To overcome this limitation, the current group recently introduced a novel patient stratification system using latent class analyses of clinical parameters, including patterns of missing teeth. This investigation sought to determine the clinical utility of the Periodontal Profile Classes and Tooth Profile Classes (PPC/TPC) taxonomy for risk assessment, specifically for predicting periodontal disease progression and incident tooth loss. The analytic sample comprised 4,682 adult participants of two prospective cohort studies (Dental Atherosclerosis Risk in Communities Study and Piedmont Dental Study) with information on periodontal disease progression and incident tooth loss. The PPC/TPC taxonomy includes seven distinct PPCs (person-level disease pattern and severity) and seven TPCs (tooth-level disease). Logistic regression modeling was used to estimate relative risks (RR) and 95% confidence intervals (CI) for the association of these latent classes with disease progression and incident tooth loss, adjusting for examination center, race, sex, age, diabetes, and smoking. To obtain personalized outcome propensities, risk estimates associated with each participant's PPC and TPC were combined into person-level composite risk scores (Index of Periodontal Risk [IPR]). Individuals in two PPCs (PPC-G: Severe Disease and PPC-D: Tooth Loss) had the highest tooth loss risk (RR = 3.6; 95% CI = 2.6 to 5.0 and RR = 3.8; 95% CI = 2.9 to 5.1, respectively). PPC-G also had the highest risk for periodontitis progression (RR = 5.7; 95% CI = 2.2 to 14.7). Personalized IPR scores were positively associated with both periodontitis progression and tooth loss. These findings, upon additional validation, suggest that the periodontal/tooth profile classes and the derived personalized propensity scores provide clinical periodontal definitions that reflect disease patterns in the population and offer a useful system for patient stratification that is predictive for disease progression and tooth loss. © 2018 American Academy of Periodontology.

Effect of dried sunflower seeds on incisal edge abrasion: A rare case report.

PubMed

Rath, Avita; Ramamurthy, Priyadarshini H; Fernandes, Bennete Aloysius; Sidhu, Preena

2017-01-01

Tooth surface loss (TSL) is a complex phenomenon characterized by the loss of hard tooth structure at various locations of the teeth, usually due to more than one factor. TSL due to abrasion can be significant in patients consuming coarse, abrasive diet. The present case reports an interesting incisal edge abrasion in a female patient, attributed to a particular dietary behavior of long-term consumption of sunflower seeds. All her family members and most of the people from her native place were also reported to have similar lesions by the patient. Larger epidemiological studies to assess the prevalence and severity of such abrasive lesions in geographic areas with this particular dietary habit need to be carried out so that people may be made aware and educated about alternative ways of eating sunflower seeds that will not cause any form of tooth wear.

Consequences of tooth loss: 2. Dentist considerations--restorative problems and implications.

PubMed

Craddock, Helen L

2010-01-01

Partial tooth loss is much less well tolerated by patients than was previously the case and, on occasions, when extraction is inevitable, they may seek prosthetic replacement. This paper explores some of the consequences of tooth loss that may cause difficulties in tooth replacement, particularly if replacement is delayed for some time. An awareness of potential difficulties, particularly with posterior tooth replacement, will allow clinicians to make treatment decisions in the light of current evidence.

Effects of 45S5 bioglass on surface properties of dental enamel subjected to 35% hydrogen peroxide

PubMed Central

Deng, Meng; Wen, Hai-Lin; Dong, Xiao-Li; Li, Feng; Xu, Xin; Li, Hong; Li, Ji-Yao; Zhou, Xue-Dong

2013-01-01

Tooth bleaching agents may weaken the tooth structure. Therefore, it is important to minimize any risks of tooth hard tissue damage caused by bleaching agents. The aim of this study was to evaluate the effects of applying 45S5 bioglass (BG) before, after, and during 35% hydrogen peroxide (HP) bleaching on whitening efficacy, physicochemical properties and microstructures of bovine enamel. Seventy-two bovine enamel blocks were prepared and randomly divided into six groups: distilled deionized water (DDW), BG, HP, BG before HP, BG after HP and BG during HP. Colorimetric and microhardness tests were performed before and after the treatment procedure. Representative specimens from each group were selected for morphology investigation after the final tests. A significant color change was observed in group HP, BG before HP, BG after HP and BG during HP. The microhardness loss was in the following order: group HP>BG before HP, BG after HP>BG during HP>DDW, BG. The most obvious morphological alteration of was observed on enamel surfaces in group HP, and a slight morphological alteration was also detected in group BG before HP and BG after HP. Our findings suggest that the combination use of BG and HP could not impede the tooth whitening efficacy. Using BG during HP brought better protective effect than pre/post-bleaching use of BG, as it could more effectively reduce the mineral loss as well as retain the surface integrity of enamel. BG may serve as a promising biomimetic adjunct for bleaching therapy to prevent/restore the enamel damage induced by bleaching agents. PMID:23743618

Effects of 45S5 bioglass on surface properties of dental enamel subjected to 35% hydrogen peroxide.

PubMed

Deng, Meng; Wen, Hai-Lin; Dong, Xiao-Li; Li, Feng; Xu, Xin; Li, Hong; Li, Ji-Yao; Zhou, Xue-Dong

2013-06-01

Tooth bleaching agents may weaken the tooth structure. Therefore, it is important to minimize any risks of tooth hard tissue damage caused by bleaching agents. The aim of this study was to evaluate the effects of applying 45S5 bioglass (BG) before, after, and during 35% hydrogen peroxide (HP) bleaching on whitening efficacy, physicochemical properties and microstructures of bovine enamel. Seventy-two bovine enamel blocks were prepared and randomly divided into six groups: distilled deionized water (DDW), BG, HP, BG before HP, BG after HP and BG during HP. Colorimetric and microhardness tests were performed before and after the treatment procedure. Representative specimens from each group were selected for morphology investigation after the final tests. A significant color change was observed in group HP, BG before HP, BG after HP and BG during HP. The microhardness loss was in the following order: group HP>BG before HP, BG after HP>BG during HP>DDW, BG. The most obvious morphological alteration of was observed on enamel surfaces in group HP, and a slight morphological alteration was also detected in group BG before HP and BG after HP. Our findings suggest that the combination use of BG and HP could not impede the tooth whitening efficacy. Using BG during HP brought better protective effect than pre/post-bleaching use of BG, as it could more effectively reduce the mineral loss as well as retain the surface integrity of enamel. BG may serve as a promising biomimetic adjunct for bleaching therapy to prevent/restore the enamel damage induced by bleaching agents.

Is the relative increase in income inequality related to tooth loss in middle-aged adults?

PubMed

Goulart, Mariél de Aquino; Vettore, Mario Vianna

2016-01-01

To assess whether Brazilian middle-aged adults living in cities that experienced a relative increase on income inequality were more likely to have severe tooth loss and lack a functional dentition. Data on Brazilian adults aged 35-44 years from state capitals and Federal District from the 2010 Brazilian Oral Health Survey (SBBrasil 2010) were analyzed. Clinically assessed tooth loss outcomes were severe tooth loss (<9 remaining natural teeth) and lack of functional dentition (<21 natural teeth). Income inequality was assessed by Gini Index in 1991, 2000, and 2003 using tertiles of distribution. Variation in Gini Index was assessed by changes in the tertiles distribution between years. Multilevel logistic regression models were used to estimate odds ratios (ORs) and 95 percent confidence intervals (95 percent CI) between variation in income inequality and tooth loss outcomes adjusting for individual socio-demographic characteristics. Prevalence of severe tooth loss and lack of functional dentition was 4.8 percent and 21.2 percent, respectively. Individuals living in cities with moderate and high increase in income inequality between 1991 and 2003 were more likely to have severe tooth loss and lack a functional dentition in 2010 compared with those living in cities with stable income inequality in the same period. Relationships between low family income and both tooth loss outcomes were significantly attenuated by relative increases in income inequality. Relative increases in income inequality were significantly associated with severe tooth loss and lack of a functional dentition in Brazilian middle-aged adults. © 2015 American Association of Public Health Dentistry.

Tooth loss, systemic inflammation, and prevalent stroke among participants in the reasons for geographic and racial difference in stroke (REGARDS) study.

PubMed

You, Zhiying; Cushman, Mary; Jenny, Nancy S; Howard, George

2009-04-01

Periodontal disease results in tooth loss, may contribute to systemic inflammation, and is associated with stroke. We examined cross-sectional associations between tooth loss, inflammation markers, stroke, race, and geographic region among participants in the reasons for geographic and racial differences in stroke (REGARDS) study of whites and blacks > or =45 years. We studied 24,393 participants. Associations of tooth loss and inflammation markers (C-reactive protein (CRP), white blood cell count (WBC) and albumin) were examined by linear regression, and associations of tooth loss with geographic region, race, and prevalent stroke by logistic regression. Compared to whites, blacks had an odds ratio of 1.48 (95% confidence interval 1.37-1.60) of having more teeth lost. There were no geographic differences in tooth loss. Compared to no tooth loss, those with 17-32 teeth lost had 1.17mg/L higher CRP (p<0.0001) and 0.18x10(9)/L higher WBC (p=0.008), did not differ in albumin, and had an odds ratio of prevalent stroke of 1.28 (1.09-1.49). Those with 1-16 teeth lost did not differ in CRP and WBC, had 0.03g/dL higher albumin (p=0.004), and had no increased stroke prevalence. CRP or WBC did not attenuate associations between tooth loss and stroke. Tooth loss, which varied with race, but not region of residence, was associated with inflammation markers and stroke. The latter association was not confounded by inflammation markers.

Incidence of attachment loss of canines in an overdenture population.

PubMed

Ettinger, Ronald L; Qian, Fang

2014-12-01

Caries and periodontal disease are the most common cause of tooth loss in overdenture populations. Longitudinal data on attachment loss in this population have not been well reported. The purpose of this longitudinal study was to measure periodontal attachment loss in overdenture abutments. In this longitudinal overdenture study, 272 persons fulfilled all of the inclusion criteria. These persons had 662 teeth, 465 (70.2%) of which were canines. This report focused only on participants with canines who returned for 3 consecutive recalls in the 42 months of the study and included 53 persons with 116 canines. During this 42-month period, 6 teeth were extracted. Attachment loss was measured at baseline and at 6 to 18 months, 19 to 30 months, and 31 to 42 months at the mesial, distal, mid-buccal, and mid-lingual surface of each tooth, and was calculated as the combination of pocket probing depth plus height above the gingiva. Attachment loss was compared at each recall. A single examiner made all the measurements. At baseline, the greatest amount of loss was at the mid-buccal surface (5.43 mm), followed by the mid-lingual (4.95 mm), distal (4.41 mm), and mesial (4.35 mm) surfaces. This pattern of attachment loss did not change over the 3 time periods, except that, at the 6 to 18-month recall, the distal measurement was less than at baseline. This decrease could be due to the wear of the abutment or loss of a restoration due to caries. Attachment loss was greater on the mandibular abutments than on the maxillary abutments and could be due to the greater amount of movement of the mandibular overdenture, especially in a buccolingual direction. Attachment loss varied by arch and by site in patients who wore overdentures. Copyright © 2014.

Associations between tooth loss and prognostic biomarkers and the risk for cardiovascular events in patients with stable coronary heart disease.

PubMed

Vedin, Ola; Hagström, Emil; Östlund, Ollie; Avezum, Alvaro; Budaj, Andrzej; Flather, Marcus D; Harrington, Robert A; Koenig, Wolfgang; Soffer, Joseph; Siegbahn, Agneta; Steg, Philippe Gabriel; Stewart, Ralph A H; Wallentin, Lars; White, Harvey D; Held, Claes

2017-10-15

Underlying mechanisms behind the hypothesized relationship between periodontal disease (PD) and coronary heart disease (CHD) have been insufficiently explored. We evaluated associations between self-reported tooth loss- a marker of PD- and prognostic biomarkers in 15,456 (97%) patients with stable CHD in the global STABILITY trial. Baseline blood samples were obtained and patients reported their number of teeth according to the following tooth loss levels: "26-32 (All)" [lowest level], "20-25", "15-19", "1-14", and "No Teeth" [highest level]. Linear and Cox regression models assessed associations between tooth loss levels and biomarker levels, and the relationship between tooth loss levels and outcomes, respectively. After multivariable adjustment, the relative biomarker increase between the highest and the lowest tooth loss level was: high-sensitivity C-reactive protein 1.21 (95% confidence interval, 1.14-1.29), interleukin 6 1.14 (1.10-1.18), lipoprotein-associated phospholipase A 2 activity 1.05 (1.03-1.06), growth differentiation factor 15 1.11 (1.08-1.14), and N-terminal pro-B-type natriuretic peptide (NT-proBNP) 1.18 (1.11-1.25). No association was detected for high-sensitivity troponin T 1.02 (0.98-1.05). Some attenuation of the relationship between tooth loss and outcomes resulted from the addition of biomarkers to the multivariable analysis, of which NT-proBNP had the biggest impact. A graded and independent association between tooth loss and several prognostic biomarkers was observed, suggesting that tooth loss and its underlying mechanisms may be involved in multiple pathophysiological pathways also implicated in the development and prognosis of CHD. The association between tooth loss and cardiovascular death and stroke persisted despite comprehensive adjustment including prognostic biomarkers. www.clinicaltrials.gov; NCT00799903. Copyright © 2017 Elsevier B.V. All rights reserved.

Enamel mineral loss.

PubMed

West, Nicola X; Joiner, Andrew

2014-06-01

To summarise the chemical, biological and host factors that impact enamel mineral loss, to highlight approaches to contemporary management of clinical conditions involving mineral loss and summarise emerging trends and challenges in this area. "Medline" and "Scopus" databases were searched electronically with the principal key words tooth, enamel, *mineral*, caries and erosion. Language was restricted to English and original studies and reviews were included. Conference papers and abstracts were excluded. Enamel mineral loss leads to the degradation of the surface and subsurface structures of teeth. This can impact their shape, function, sensitivity and aesthetic qualities. Dental caries is a multifactorial disease caused by the simultaneous interplay of dietary sugars, dental plaque, the host and time. There is a steady decline in dental caries in developed countries and the clinical management of caries is moving towards a less invasive intervention, with risk assessment, prevention, control, restoration and recall. Tooth wear can be caused by erosion, abrasion and attrition. Dental erosion can be the result of acid from intrinsic sources, such as gastric acids, or extrinsic sources, in particular from the diet and consumption of acidic foods and drinks. Its prevalence is increasing and it increases with age. Clinical management requires diagnosis and risk assessment to understand the underlying aetiology, so that optimal preventative measures can be implemented. Overall, prevention of enamel mineral loss from caries and tooth wear should form the basis of lifelong dental management. Evidence based oral hygiene and dietary advice is imperative, alongside preventive therapy, to have a healthy lifestyle, whilst retaining hard tooth tissue. © 2014 Elsevier Ltd. All rights reserved.

Properties of cutoff corrugated surfaces for corrugated horn design. [corrugation shape and density effects on scattering

NASA Technical Reports Server (NTRS)

Mentzer, C. A.; Peters, L., Jr.

1974-01-01

Corrugated horns involve a junction between the corrugated surface and a conducting ground plane. Proper horn design requires an understanding of the electromagnetic properties of the corrugated surface and this junction. An integral equation solution has been used to study the influence of corrugation density and tooth thickness on the power loss, surface current, and the scattering from a ground plane/corrugated surface junction.

Dissolution of Enamel on Exposure to Various Commercial Beverages Available in India.

PubMed

Panda, Abikshyeet; Ghosh, Bikramaditya; Pal, Imon; Kumar, Vijay; Bhuyan, Lipsa; Dash, Kailash C

2017-11-01

The study was aimed to estimate the pH of the commonly available soft drinks in the Indian market and to assess the detrimental effects of the juices and beverages on the tooth surface by measuring the weight loss of the tooth sample. The study was done with eight different types of commercially available carbonated drink and fruit juices available in the Indian market among which six were carbonated drinks and two were juices. Carbonated drinks experimented were Coca-Cola, Pepsi, Fanta, Mirinda, 7Up and Sprite, and two fruit juices were Tropicana orange juice and real orange juice. Ten different bottles from each category were obtained, and the pH was estimated. Each of the beverages was divided into batch of 10 containers containing the tooth sample. Weight of all samples was measured at 24, 48, 72, 96, and 120 hours with subsequently changing each solution at an interval of 24 hours. The mean pH of the beverages was found ranging from 2.13 ± 0.02 in Pepsi to 3.41 ± 0.02 in Tropicana on opening. The mean pH of water was found to be 6.98 ± 0.01. Among carbonated drinks, the mean weight loss after 24 hours was highest in Coca-Cola and least in 7Up. Tropicana fruit juice had a higher tooth loss than real orange juices. When compared with water, the tooth loss was significantly higher in Coca-Cola after all specified time (hours). The pH of both carbonated drinks and fruit juices was below the critical pH. The weight loss was also seen after every 24 hours in all the carbonated drinks and beverages. The study showed that these commercial beverages are harmful to the tooth structures, and hence, the health professionals play a major role in educating the population about its effects and advising them to use these products precisely. The change in lifestyle has increased the demand of soft drinks and artificial juice in Indian market. The use of these carbonated drinks and fruit juices causes damage to the tooth structure in all ages, especially in young mass. Our study provides an idea about the deleterious effects of these commercial drinks on dental hard tissues.

Correlation of Periodontal Disease With Inflammatory Arthritis in the Time Before Modern Medical Intervention.

PubMed

Rothschild, Bruce

2017-03-01

Controversy exists regarding possible correlation of periodontal disease with rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Confounding factors may relate to stringency of inflammatory disease diagnosis and the effect of therapeutic intervention for RA on periodontal disease. These factors are investigated in this study. Forty-five individuals with documented RA (n = 15), spondyloarthropathy (n = 15), and calcium pyrophosphate deposition disease (CPPD) (n = 15), from the Hamann-Todd collection of human skeletons compiled from 1912 to 1938, and 15 individuals contemporarily incorporated in the collection were examined for tooth loss, cavity occurrence, average and maximum lingual and buccal depth of space between tooth and bone, periosteal reaction, serpentine bone resorption, abscess formation, and root penetration of the bone surface and analyzed by analysis of variance. Tooth loss was common, but actual number of teeth lost, cavity occurrence, average and maximum lingual and buccal depth of space between tooth and bone, periosteal reaction, serpentine grooving surrounding teeth (considered a sign of inflammation), abscess formation, and root exposure (penetration of bone surface) were indistinguishable among controls and individuals with RA, spondyloarthropathy, and CPPD. Although many factors can affect periodontal disease, presence of inflammatory arthritis does not appear to be one of them. The implication is that dental disease was common in the general population and not necessarily associated with arthritis, at least before the advent of modern rheumatologic medications. As specific diagnosis did not affect prevalence, perhaps current prevalence controversy may relate to current intervention, a subject for further study.

Effects of IL6 C-634G polymorphism on tooth loss and their interaction with smoking habits.

PubMed

Suma, S; Naito, M; Wakai, K; Sasakabe, T; Hattori, Y; Okada, R; Kawai, S; Hishida, A; Morita, E; Nakagawa, H; Tamura, T; Hamajima, N

2015-09-01

To examine the association between an IL6 (Interleukin-6) polymorphism (C-634G or rs1800796) and tooth loss, and an interaction between the polymorphism and smoking habits for the loss. Our subjects were 4917 check-up examinees ages 35-69. They reported tooth loss and lifestyle in a questionnaire. We regressed the number of teeth on the IL6 genotype, gender, age, smoking, drinking, diabetes, hypertension, physical activity, energy intake, education, and brushing. We further estimated multivariate-adjusted odds ratios (ORs) for having <20 teeth. Participants with a GG genotype tended to have less teeth than those with CC; β = -0.798 (95% confidence interval [CI] = -1.501--0.096). Subjects with a GG genotype were more likely to have <20 teeth than those with CC; OR was 1.56 (95% CI = 1.08-2.25). Association between current smoking and tooth loss was stronger among those with GG than among those with CC. In a multiple regression analysis, a significant interaction was found between GG genotype and current smoking in the prediction of tooth loss (P = 0.018). The IL6 C-634G polymorphism was significantly associated with tooth loss. Our results suggest greater effects of smoking on tooth loss in GG genotype individuals. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

An in vitro evaluation of wear and surface roughness of particulate filler composite resin after tooth brushing.

PubMed

Al Khuraif, Abdul Aziz A

2014-11-01

To evaluate the influence of tooth brushing on wear and surface roughness of four different particulate filler composite resins. Six specimens (2 mm thick and 8 mm in diameter) of each tested material (Filtek Z250-Microhybrid, SpectrumTPH3-Submicron hybrid, Filtek Z350XT Nanofiller and Filtek P90- Microhybrid) were prepared according to the manufacturer's directions. A brushing sequence of 5000, 10,000 and 20,000 cycles was performed for all the samples. A non-contact profilometer was used to determine average surface roughness (Ra) and wear of the material assessed using an analytic electronic balance at baseline and each cycle interval. The data obtained were analyzed using one-way ANOVAs and post-hoc multiple comparison tests. Paired t-test was used for comparisons between cycle intervals for each material. Analyses with scanning electron microscopy (SEM) were also performed. The resin composite Filtek P 90 presented an increase in percentage weight loss after final toothbrushing cycles over the rest of the materials. Brushing significantly increased roughness (Ra) for all composites. Filtek Z250, after brushing, was significantly rougher than the other resins followed by Filtek P 90, Spectrum TPH 3 and Filtek Z350 XT. However, SEM images indicated severe change in surface topography of 'sub-micron hybrid' specimen compared to each other after tooth brushing. Wear and surface roughness increased with each cycle interval for all the materials and one composite resin demonstrated a higher increase in surface roughness than the other three tested brands of composite resins. Not much difference was observed in the weight loss between tested samples.

Management of premature primary tooth loss in the child patient.

PubMed

Law, Clarice S

2013-08-01

Premature loss of primary teeth can result in a loss of arch length and have a negative effect on occlusion and alignment, often increasing the need for orthodontic treatment. Use of space maintainers can reduce the severity of problems such as crowding, ectopic eruption, tooth impaction and poor molar relationship. This article presents a review of the consequences of premature tooth loss and discusses the appliances commonly used for space maintenance.

Permanent tooth loss and sugar-sweetened beverage intake in U.S. young adults.

PubMed

Kim, Sunkyung; Park, Sohyun; Lin, Mei

2017-03-01

In young adults, sugar-sweetened beverage (SSB) intake is associated with dental caries, which in turn is a major contributor to tooth loss. The independent role of SSB intake on tooth loss, however, has not been well-described. This cross-sectional study examined associations between tooth loss and SSB intake among U.S. young adults. The outcome was number of permanent teeth lost because of dental caries or periodontal disease (0, 1-5, ≥6 teeth). Data from the 2012 Behavioral Risk Factor Surveillance System were used. The 22,526 adults aged 18-39 years completed the Sugar Drink Module. The exposure variable was daily frequency of SSB intake. We used multinomial logistic regression to examine the adjusted associations between tooth loss and daily SSB consumption (0, >0 to <1, 1-2, >2 times/day). Approximately, 26% of young adults reported losing at least one permanent tooth. Tooth loss was positively associated with SSB intake frequency; the odds of losing 1-5 teeth were higher among adults drinking SSBs >0-<1 times/day (OR = 1.44, 95%CI = 1.16-1.79), 1-2 times/day (OR = 1.58, 95%CI = 1.25-1.99), and >2 times/day (OR = 1.97, 95%CI = 1.51-2.58) than non-SSB consumers. The odds of losing ≥6 teeth were higher among adults drinking SSBs 1-2 times/day (OR = 2.20, 95%CI = 1.15-4.22) and >2 times/day (OR = 2.81, 95%CI = 1.37-5.76) than non-SSB consumers. Frequency of SSB consumption was positively associated with tooth loss among young adults even when the average SSB intake was less than one time per day. This study suggests that efforts to reduce SSB intake among young adults may help to decrease the risk of tooth loss. © 2016 American Association of Public Health Dentistry.

Toothbrushing abrasion susceptibility of enamel and dentin bleached with calcium-supplemented hydrogen peroxide gel.

PubMed

Borges, A B; Santos, L F T F; Augusto, M G; Bonfiette, D; Hara, A T; Torres, C R G

2016-06-01

The objective of this study was to evaluate enamel and dentin susceptibility to toothbrushing abrasion, after bleaching with 7.5% hydrogen peroxide (HP) gel supplemented or not with 0.5% calcium gluconate (Ca). Toothbrushing was performed immediately and 1h after bleaching, with two suspensions (high and low abrasivity). Bovine enamel and dentin specimens were divided into 12 groups (n=10) according to the bleaching gel (with and without Ca), slurry abrasivity (high or low) and elapsed time after bleaching (immediately and after 1h). As control, a group was not bleached, but abraded. The treatment cycle (7 d) consisted of bleaching (1h) and toothbrushing (135 strokes/day) immediatelly or after 1h of artificial saliva exposure. Surface roughness and surface loss (μm) were measured by profilometry and analysed by three-way ANOVA (5%). Surface roughness means were significantly influenced by slurry abrasivity (p<0.0001). For enamel loss, significant triple interaction was observed (p<0.0001). HP-bleached groups and immediately brushed with high-abrasive slurry exhibited increased loss (1.41±0.14) compared to other groups (μm). Control and HP+Ca-bleached groups brushed after 1h with low abrasive slurry presented the lowest loss (0.21±0.03/0.27±0.02). For dentin loss, significant interaction was observed for bleaching and interval factors (p<0.001). 7.5%HP-bleached groups and immediately brushed showed significantly higher loss (8.71±2.45) than the other groups. It was concluded that surface roughness increased when high abrasive was used, independently of bleaching. 7.5%HP increased enamel and dentin loss, mainly with high abrasive slurries. Calcium supplementation of bleaching gel reduced surface loss. Additionally, in order to minimize tooth wear susceptibility, it is recommended to delay brushing after bleaching. After bleaching gel application, postponing toothbrushing is recommended, as well as brushing with low abrasive dentifrices. Additionally, supplementation of hydrogen peroxide gel with calcium-based remineralizing agent potentially reduces tooth loss after abrasion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Complete tooth loss as status passage.

PubMed

Gibson, Barry John; Sussex, Philip V; Fitzgerald, Ruth P; Thomson, William Murray

2017-03-01

The aim of this article is to add to the literature on the sociology of oral health and dentistry by presenting the relevance of status passage to the study of complete tooth loss. The article reports on an analysis of data taken from participants residing in the Nelson region of New Zealand. In total the data include interviews from 20 participants, all of whom had their remaining natural teeth removed before 1960. In total, 12 women and eight men were interviewed. All were from a European background with an age range of 71 to 101 years. Following a narrative approach, participants were interviewed on the nature of the social factors that resulted in complete tooth loss by starting with their family history and then focusing on the factors and events leading up to their total tooth loss. Data were analysed using the methods and techniques of grounded theory. This article provides an outline of the importance of scheduling, prescribing, social factors, 'compound awareness contexts' and reversibility to the status passage into complete tooth loss. We conclude by arguing that the theory of status passage may enable a detailed analysis of the 'time-space extensionality' of trajectories into complete tooth loss. © 2016 Foundation for the Sociology of Health & Illness.

Association between Dental Health and Osteoporosis: A Study in South Indian Postmenopausal Women.

PubMed

Kapoor, Nitin; Cherian, Kripa Elizabeth; Pramanik, Binay Kumar; Govind, S; Winford, Manna Elizabeth; Shetty, Sahana; Thomas, Nihal; Paul, Thomas Vizhalil

2017-01-01

This study aims to objectively assess the dentition status in South Indian postmenopausal women and compare the dental health of osteoporotic participants with nonosteoporotic individuals. A total of 150 consecutive ambulatory South Indian postmenopausal women (>50 years of age) were assessed for their dental health using an internationally validated scoring system. Bone mineral density (BMD) was assessed using a dual-energy X-ray absorptiometry scanner. About 39% of the participants were found to have osteoporosis and 23% had osteopenia at any site. More than half of them (57%) had poor dental health, and the predominant problems were cavities (43.5%) and loss of teeth (75%). Among 112 women who had tooth loss, the mean tooth loss was 4.8. The mean tooth loss among patients with normal BMD was 1.09 ± 1.2, in osteopenia was 2.1 ± 2, and in osteoporosis was 5.4 ± 2.8 ( P < 0.01). The odds of having osteoporosis among the patients with three or more tooth loss were found to be 4.2 (95% confidence interval = 2.4-7.3). Postmenopausal women with osteoporosis had significantly higher number of tooth loss. Tooth loss may thus be used as a surrogate marker to predict osteoporosis.

Tooth loss in middle-aged adults with diabetes and hypertension: Social determinants, health perceptions, oral impact on daily performance (OIDP) and treatment need

PubMed Central

Maia, Fabiana-Barros-Marinho; Sampaio, Fábio-Correia; Freitas, Cláudia-Helena-Soares-de Morais; Forte, Franklin-Delano-Soares

2018-01-01

Background This study aimed to explore the association between tooth loss and social determinants, health self-perceptions, OIDP and self-concept of dental treatment need in middle-aged adults with diabetes and hypertension. Material and Methods A cross-sectional study was developed with 212 hypertensive and diabetic middle-aged adults (50-65 years). Data were collected from clinical examinations (DMFT) and a questionnaire regarding socioeconomic status, dental health assistance, self-perceptions of oral and general health, OIDP, and the self-concept of dental treatment need. Tooth loss was dichotomized considering the cutoff point of 12 (Model I) or 24 missing teeth (Model II). Data were analyzed using Chi-square, Fisher’s exact test and logistic regression (p≤0.05). Results Tooth loss was significantly associated with variables such as last dental visit, reason for dental visit, OIDP, perception of dental treatment need, and general self-perception (Model I). Schooling, last dental visit, oral health self-perception and perception of dental treatment need were significantly associated with tooth loss in the Model II. When Model 1 and 2 were adjusted, they demonstrated that last dental visit and perception of dental treatment need were predictor variables. Conclusions The annual dental visit and the self-concept of dental treatment need were associated with tooth loss, demonstrating that these variables reduce the tooth loss prevalence. Key words:Access /barriers to care, Dental treatment, Geriatric dentistry. PMID:29476679

Investigation and treatment of patients with teeth affected by tooth substance loss: a review.

PubMed

Watson, M L; Burke, F J

2000-05-01

Tooth substance loss, an increasing problem, may result from erosion, abrasion and attrition, often with more than one of these acting together. Investigation requires a detailed history and examination. The aim of treatment may be prevention of further damage in less affected cases. The treatment of severe tooth substance loss may be complex, especially in view of the reduced amounts of tooth substance which may be available and the need to find space because of the compensatory over-eruption of worn teeth.

Inequality in oral health related to early and later life social conditions: a study of elderly in Norway and Sweden.

PubMed

Gülcan, Ferda; Ekbäck, Gunnar; Ordell, Sven; Lie, Stein Atle; Åstrøm, Anne Nordrehaug

2015-02-10

A life course perspective recognizes influences of socially patterned exposures on oral health across the life span. This study assessed the influence of early and later life social conditions on tooth loss and oral impacts on daily performances (OIDP) of people aged 65 and 70 years. Whether social inequalities in oral health changed after the usual age of retirement was also examined. In accordance with "the latent effect life course model", it was hypothesized that adverse early-life social conditions increase the risk of subsequent tooth loss and impaired OIDP, independent of later-life social conditions. Data were obtained from two cohorts studies conducted in Sweden and Norway. The 2007 and 2012 waves of the surveys were used for the present study. Early-life social conditions were measured in terms of gender, education and country of birth, and later-life social conditions were assessed by working status, marital status and size of social network. Logistic regression and Generalized Estimating Equations (GEE) were used to analyse the data. Inverse probability weighting (IPW) was used to adjust estimates for missing responses and loss to follow-up. Early-life social conditions contributed to tooth loss and OIDP in each survey year and both countries independent of later-life social conditions. Lower education correlated positively with tooth loss, but did not influence OIDP. Foreign country of birth correlated positively with oral impacts in Sweden only. Later-life social conditions were the strongest predictors of tooth loss and OIDP across survey years and countries. GEE revealed significant interactions between social network and survey year, and between marital status and survey year on tooth loss. The results confirmed the latent effect life course model in that early and later life social conditions had independent effects on tooth loss and OIDP among the elderly in Norway and Sweden. Between age 65 and 70, inequalities in tooth loss related to marital status declined, and inequalities related to social network increased.

Periodontal disease, tooth loss and coronary heart disease assessed by coronary angiography: a cross-sectional observational study.

PubMed

Zanella, S M; Pereira, S S; Barbisan, J N; Vieira, L; Saba-Chujfi, E; Haas, A N; Rösing, C K

2016-04-01

To evaluate the association between periodontal disease, tooth loss and coronary heart disease (CHD). There is still controversy about the relationship between periodontal disease and tooth loss with vessel obstruction assessed using coronary angiography. This cross-sectional study included 195 patients that underwent coronary angiography and presented with at least six teeth. Patients were classified into three categories of coronary obstruction severity: absence; one or more vessels with ≤ 50% obstruction; and one or more vessels with ≥ 50% obstruction. The extent of coronary obstruction was dichotomized into 0 and ≥ 1 affected vessels. A periodontist blinded to patient CHD status conducted a full mouth examination to determine mean clinical attachment loss, mean periodontal probing depth and tooth loss. Multiple logistic regression models were applied adjusting for age, gender, hypertension, smoking, body mass index, low-density lipoprotein cholesterol and C-reactive protein. Most patients were males (62.1%) older than 60 years (50.8%), and 61% of them had CHD. Mean periodontal probing depth, clinical attachment loss and tooth loss were 2.64 ± 0.72 mm, 4.40 ± 1.31 mm and 12.50 ± 6.98 teeth respectively. In the multivariable models, tooth loss was significantly associated with a higher chance of having at least one obstructed vessel (odds ratio = 1.04; 95% confidence interval 1.01-1.09) and with vessel obstruction ≥ 50% (odds ratio = 1.06; 95% confidence interval 1.01-1.11). No significant associations were found between periodontal variables and vessel obstruction. Tooth loss was found to be a risk indicator for CHD. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Risk indicators for tooth loss in Kiriri Adult Indians: a cross-sectional study.

PubMed

Ribeiro, Livia S F E; Dos Santos, Jean N; Ramalho, Luciana M P; Chaves, Sonia; Figueiredo, Andreia Leal; Cury, Patricia Ramos

2015-12-01

The aim of this cross-sectional study was to evaluate the risk indicators of tooth loss in adult Kiriri Indians from Brazil. A representative sample of 225 Indians (≥ 19 years of age) was assessed. Interviews using a structured written questionnaire were performed to collect data on demographics and socio-economic status, and health-related data. Probing depth, the distance between the cement-enamel junction and the free gingival margin, and decayed, missing or filled teeth were evaluated. Bivariate and logistic models were used to assess associations between tooth loss and age, sex, income, education, diabetic status, smoking habits, dental caries, severe periodontitis, plaque index and previous dental visit. Eighty per cent of subjects had lost one tooth or more, and 20% had lost eight teeth or more. Mean (± standard deviation) tooth loss was 5.09 (± 5.83) teeth. After adjustment for covariates, loss of one tooth or more was associated with older age [≥ 35 years; odds ratio (OR) = 4.06, 95% confidence interval (95% CI): 1.38-11.94, P = 0.01], severe periodontitis (OR = 3.35, 95% CI: 0.99-11.24, P = 0.05), higher dental caries (OR = 3.24, 95% CI: 1.35-7.78, P = 0.01) and previous dental visit (OR = 23.32, 95% CI: 5.75-94.63, P < 0.001). Tooth loss is highly prevalent in Kiriri Indians. Older age, severe periodontitis, higher caries index and previous dental visit were associated with tooth loss. Prevention and treatment programmes, targeting high-risk groups, are required to promote the oral health of the population. © 2015 FDI World Dental Federation.

Association of parental education with tooth loss among Korean Elders.

PubMed

Han, Dong-Hun; Khang, Young-Ho; Choi, Ho-Jun

2015-12-01

There are few reports showing an association between childhood socioeconomic circumstances and tooth loss among the elderly. The purpose of this study was (i) to examine the association between early childhood socioeconomic position (parental education level) and tooth loss and (ii) to determine the relative effects of the subjects' education level, occupation, and income on tooth loss in Korean elders. Data from the fourth and fifth Korea National Health and Nutritional Examination Survey on 8814 Korean elders (age ≥65 years) were analyzed. Demographic factors (age, survey year, marital status, and residence area), health behaviors (dental check-up during the past year and cigarette smoking), and the presence of a somatic health problem (diabetes) were included in our gender-specific analyses. Tooth loss was defined as edentulism or severe tooth loss (<20 teeth). For our analyses, chi-square test and Student's t-tests and multiple logistic regressions were performed. A low parental education level was associated with elevated odds of edentulism (OR = 1.87 for father's education and 1.52 for mother's education among male elders and OR = 1.73 for father's education and 1.55 for mother's education among female elders) and with severe tooth loss (OR = 1.58 for father's education and 1.53 for mother's education among male elders and OR = 1.25 for father's education and 1.48 for mother's education among female elders). The association between parental education level and tooth loss was attenuated after adjusting for the subject's education level, occupation, and income. Relative magnitude of attenuation varied with personal factors (education > income > occupation). In a fully adjusted model, father's education level was significantly associated with edentate status (OR = 1.96 for male elders and 1.46 for female elders), but not with severe tooth loss. Our results indicate that early life socioeconomic circumstances measured by the father's education level were independently associated with the edentate status of Korean elders. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Accuracy in Dental Medicine, A New Way to Measure Trueness and Precision

PubMed Central

Ender, Andreas; Mehl, Albert

2014-01-01

Reference scanners are used in dental medicine to verify a lot of procedures. The main interest is to verify impression methods as they serve as a base for dental restorations. The current limitation of many reference scanners is the lack of accuracy scanning large objects like full dental arches, or the limited possibility to assess detailed tooth surfaces. A new reference scanner, based on focus variation scanning technique, was evaluated with regards to highest local and general accuracy. A specific scanning protocol was tested to scan original tooth surface from dental impressions. Also, different model materials were verified. The results showed a high scanning accuracy of the reference scanner with a mean deviation of 5.3 ± 1.1 µm for trueness and 1.6 ± 0.6 µm for precision in case of full arch scans. Current dental impression methods showed much higher deviations (trueness: 20.4 ± 2.2 µm, precision: 12.5 ± 2.5 µm) than the internal scanning accuracy of the reference scanner. Smaller objects like single tooth surface can be scanned with an even higher accuracy, enabling the system to assess erosive and abrasive tooth surface loss. The reference scanner can be used to measure differences for a lot of dental research fields. The different magnification levels combined with a high local and general accuracy can be used to assess changes of single teeth or restorations up to full arch changes. PMID:24836007

Ultrastructure of the surface of dental enamel with molar incisor hypomineralization (MIH) with and without acid etching.

PubMed

Bozal, Carola B; Kaplan, Andrea; Ortolani, Andrea; Cortese, Silvina G; Biondi, Ana M

2015-01-01

The aim of the present work was to analyze the ultrastructure and mineral composition of the surface of the enamel on a molar with MIH, with and without acid etching. A permanent tooth without clinical MIH lesions (control) and a tooth with clinical diagnosis of mild and moderate MIH, with indication for extraction, were processed with and without acid etching (H3PO4 37%, 20") for observation with scanning electron microscope (SEM) ZEISS (Supra 40) and mineral composition analysis with an EDS detector (Oxford Instruments). The control enamel showed normal prismatic surface and etching pattern. The clinically healthy enamel on the tooth with MIH revealed partial loss of prismatic pattern. The mild lesion was porous with occasional cracks. The moderate lesion was more porous, with larger cracks and many scales. The mineral composition of the affected surfaces had lower Ca and P content and higher O and C. On the tooth with MIH, even on normal looking enamel, the demineralization does not correspond to an etching pattern, and exhibits exposure of crystals with rods with rounded ends and less demineralization in the inter-prismatic spaces. Acid etching increased the presence of cracks and deep pores in the adamantine structure of the enamel with lesion. In moderate lesions, the mineral composition had higher content of Ca, P and Cl. Enamel with MIH, even on clinically intact adamantine surfaces, shows severe alterations in the ultrastructure and changes in ionic composition, which affect the acid etching pattern and may interfere with adhesion.

Qualitative Assessment of Wear Resistance and Surface Hardness of Different Commercially Available Dental Porcelain: An in vitro Study.

PubMed

Singh, Abhishek; Nagpal, Abhishek; Pawah, Salil; Pathak, Chetan; Issar, Gaurav; Sharma, Pankaj

2016-09-01

In an attempt to minimize wear damage to the enamel of antagonist teeth, new low and medium fusing ceramic materials have been developed. Manufacturers usually claim that these ceramics are wear-friendly because of their lower hardness, lower concentrations of crystal phase, and smaller crystal sizes. This study aimed to quantitatively analyze the wear strength of various commercially available dental porcelain with tooth enamel as well as the surface hardness of these dental porcelain. The basic model was designed as a pin on plate arrangement. The tooth specimens were mounted on the stylus which was centered on the ceramic specimen in a wear testing machine. The dental ceramic specimen was centered in the metal die. A load of 40 N was applied at a rate of 80 cycles/minute for 15 minutes. In the current study, mean wear depth (Ra) value, volumetric loss, and surface hardness were obtained by standard quantification method and were statistically evaluated. Ceramco-3 was reported to be most abrasive for enamel; however, Duceram love significantly more abraded itself than the other two, Ceramco-3 and Vita Alpha, and generated the lowest loss of enamel. Also, same abrasive type of wear was revealed for all three variants of tested ceramics. Ceramco-3 was the most abrasive for enamel, while surface roughness (mean wear depth) of Duceram love was maximum and for Ceramco-3 it was minimum. The value of surface roughness for Vita Alpha was in between Duceram love and Ceramco-3. Nonetheless, the mean surface hardness of Duceram love was found to be least and maximum for Vita Alpha. In situations of dental wear and wasting tooth disease (Attrition/Abrasion), Duceram can be applied in lieu of Ceramco-3 so as to prevent worsening of existing dentition. However, in younger patients Vita Alpha would offer maximum durability due to its greater surface hardness.

Evaluation of cross-polarized near infrared hyperspectral imaging for early detection of dental caries

NASA Astrophysics Data System (ADS)

Usenik, Peter; Bürmen, Miran; Fidler, Aleš; Pernuš, Franjo; Likar, Boštjan

2012-01-01

Despite major improvements in dental healthcare and oral hygiene, dental caries remains one of the most prevalent oral diseases and represents the primary cause of oral pain and tooth loss. The initial stages of dental caries are characterized by demineralization of enamel crystals and are difficult to diagnose. Near infrared (NIR) hyperspectral imaging is a new promising technique for detection of early changes in the surfaces of carious teeth. This noninvasive imaging technique can characterize and differentiate between the sound tooth surface and initial or advanced tooth caries. The absorbing and scattering properties of dental tissues reflect in distinct spectral features, which can be measured, quantified and used to accurately classify and map different dental tissues. Specular reflections from the tooth surface, which appear as bright spots, mostly located around the edges and the crests of the teeth, act as a noise factor which can significantly interfere with the spectral measurements and analysis of the acquired images, degrading the accuracy of the classification and diagnosis. Employing cross-polarized imaging setup can solve this problem, however has yet to be systematically evaluated, especially in broadband hyperspectral imaging setups. In this paper, we employ cross-polarized illumination setup utilizing state-of-the-art high-contrast broadband wire-grid polarizers in the spectral range from 900 nm to 1700 nm for hyperspectral imaging of natural and artificial carious lesions of various degrees.

Elderly complete denture wearers: a social approach to tooth loss.

PubMed

Papadaki, Eftychia; Anastassiadou, Vassiliki

2012-06-01

To correlate emotional reactions to tooth loss with denture satisfaction attributes in elderly complete denture wearers. Total tooth loss is a serious life event, and poor oral health has an impact on daily life. Edentulism treated by rehabilitation with dentures can have a positive effect on patients' self-image and social behaviour. A group of 80 edentulous subjects undergoing routine prosthetic care in a Greek Department of Prosthetic Dentistry were interviewed using two structured questionnaires. The first questionnaire explored reactions to tooth loss, whereas the second measured their subjective experience of complete dentures. The responses to both questionnaires were compared using the statistical package SPSS v.17. The results showed significant correlation between aspects of tooth loss experience and complete denture satisfaction. Despite the fact that a substantial proportion of patients were satisfied with their complete dentures, some patients experienced increased social and psychological problems related to their edentulousness and the wearing of complete dentures. The aesthetic and functional aspects of complete dentures affected both patients' social behaviour and self-confidence. Total tooth loss was not only reflected in patient's social behaviour and self-image, but it had a complex and multifaceted impact on satisfaction from complete dentures. © 2011 The Gerodontology Society and John Wiley & Sons A/S.

'Your whole life is lived through your teeth': biographical disruption and experiences of tooth loss and replacement.

PubMed

Rousseau, Nikki; Steele, Jimmy; May, Carl; Exley, Catherine

2014-03-01

The experience and meaning of tooth loss and replacement has varied historically and culturally but has received relatively little attention from social scientists. Our study set out to understand these experiences in the context of the arrival of newer, dental implant treatments. Semi-structured qualitative interviews were carried out with 39 men and women who had experienced tooth loss and replacement. A thematic analysis was sensitised by previous sociological work on chronic illness, particularly Bury's notion of biographical disruption. We found that while for some individuals the loss of a tooth was relatively insignificant, for others it was devastating and disruptive. In seeking to understand this difference, the concept of biographical disruption was a helpful analytical tool. Our analysis identified two forms of disruption. The first related to the meanings of tooth loss (the neglected mouth) and denture wearing (a marker of old age). The second, embodied, disruption concerned the relationship between the self and mouth in those wearing dentures (the invaded, unreliable mouth) and could occur even where tooth loss and denture wearing had been biographically anticipated. © 2013 The Authors. Sociology of Health & Illness © 2013 Foundation for the Sociology of Health & Illness/John Wiley & Sons Ltd.

Managing the maxillary partially edentulous patient with extensive anterior tooth loss and advanced periodontal disease using a removable partial denture: a clinical report.

PubMed

Ma, Polly S; Brudvik, James S

2008-10-01

The treatment modality, a continuous occlusal rest removable partial denture, not only restored missing teeth but also stabilized the remaining dentition in a patient with advanced periodontal attachment loss. By engaging the guiding planes at the mesial surfaces of the abutments anteriorly and also the distal surfaces of the abutments posteriorly, the remaining teeth, with varying amounts of mobility, were splinted together by the framework. This conservative treatment option allows flexibility for easy repair during the life span of the prosthesis.

[Cryopreservation of teeth].

PubMed

Zimmerli, Melanie; Filippi, Andreas

2010-01-01

After tooth loss dental implants or fixed prosthetic restorations are not indicated in children and adolescents due to incomplete maxillary and mandibular development. Cryopreservation is a method for long-term storage of healthy teeth which were removed for orthodontic reasons or due to traumatic origin. These preserved teeth can be used as autogenous replants or transplants after tooth loss. During transport to and from the freezing facilities prior to freezing the teeth are stored in a cell culture medium. The tooth is transferred into a freezing tube containing cell culture medium and cryoprotectant DMSO. Teeth autotransplanted after cryopreservation show vitality of the PDL cells. Usually no enamel and/or dentinal cracks can be observed. After tooth loss transplantation of cryopreserved teeth could be an effective and biological therapy for tooth replacement.

Socio-behavioral predictors of changes in dentition status: a prospective analysis of the 1942 Swedish birth cohort.

PubMed

Åstrøm, Anne N; Ekback, Gunnar; Ordell, Sven; Unell, Lennart

2011-08-01

Using a prospective cohort design, this study assessed loss of natural teeth between ages 50 and 65. Guided by a conceptual framework grouping variables according to the life-course stage at which they would be expected to operate, this study assessed the impacts of socio-behavioral and disease-related factors on tooth loss between ages 50 and 65. In 1992, all 50-year-olds in two counties of Sweden were invited to participate in a longitudinal questionnaire survey. Of the total population of 8,888 subjects, 6,346 responded (71.4%). Of the 6346 subjects who completed the 1992 questionnaire, 4,143 (65%) completed postal follow-ups at ages 55, 60 and 65. For the total sample, the prevalence of having lost at least some teeth increased from 76% at age 50-85.5% at age 65. A total of 14% women and 13% men changed from having all teeth in 1992 to having tooth loss in 2007. Stepwise logistic regression analyses focused on predictors of tooth loss between 1992 and 2007. The following life-stage predictors achieved or approached statistical significance with respect to overall tooth loss; country of birth and education (early life and young adult life stage), marital status, dental care avoidance because of high cost, smoking and reporting consistent pain (middle-age and early-old-age life stage). Fewer substantial proportions of the 1942 cohort experienced tooth loss between ages 50 and 65. Tooth loss was highly prevalent from age 50 and increased moderately with increasing age. Oral disease-related factors and socio-behavioral characteristics such as refraining from dental care because of financial limitations, acting at earlier and later life-course stages were major risk factors for having tooth loss. Early primary prevention of smoking and increased equitable access to dental care might improve tooth retention throughout the transition from middle age to early-older age. © 2010 John Wiley & Sons A/S.

Abrasion resistance of direct and indirect resins as a function of a sealant veneer.

PubMed

Ferraz Caneppele, Taciana Marco; Rocha, Daniel Maranha; Màximo Araujo, Maria Amelia; Valera, Màrcia Carneiro; Salazar Marocho, Susana MarIa

2014-01-01

Abrasive wear is one of the most common type of wear that not only affect teeth, as also dental restorations. Thus to investigate one of the etiological factors as tooth brushing procedure is clinical relevant in order to select the best material combination that may prevent damage of resin dental restoration's abrasion. This study evaluated the influence of tooth brushing on mass loss and surface roughness of direct Venus (Vs) and indirect Signum (Sg) resin composites, with and without a surface sealant, Fortify (F). Twenty-four specimens were prepared with each resin composite, using their proprietary curing units, according to manufacturer's instructions. All the specimens were polished and ultrasonically cleaned in distilled water for 5 minutes. Half of the specimens of each resin (n = 12) were covered with F (Vs F and Sg F ), except for the control (C) specimens (Vs C and Sg C ), which were not sealed. Mass loss (ML) as well as surface roughness (Ra ) was measured for all the specimens. Then, the specimens were subjected to toothbrush-dentifrice abrasion, using a testing machine for 67.000 brushing strokes, in an abrasive slurry. After brushing simulation, the specimens were removed from the holder, rinsed thoroughly and blot dried with soft absorbent paper. The abrasion of the material was quantitatively determined with final measurements of ML and surface roughness, using the method described above. ML data were analyzed by two-way analysis of variance (ANOVA) and the analysis indicated that resin composites were not statistically different; however, the specimens sealed with F showed higher ML. Ra mean values of the groups Vs F and Sg F significantly increased. Tooth brushing affects mainly the roughness of the direct and indirect resin composites veneered with a sealant.

Enzyme Replacement Therapy Prevents Dental Defects in a Model of Hypophosphatasia

PubMed Central

McKee, M.D.; Nakano, Y.; Masica, D.L.; Gray, J.J.; Lemire, I.; Heft, R.; Whyte, M.P.; Crine, P.; Millán, J.L.

2011-01-01

Hypophosphatasia (HPP) occurs from loss-of-function mutation in the tissue-non-specific alkaline phosphatase (TNALP) gene, resulting in extracellular pyrophosphate accumulation that inhibits skeletal and dental mineralization. TNALP-null mice (Akp2-/-) phenocopy human infantile hypophosphatasia; they develop rickets at 1 week of age, and die before being weaned, having severe skeletal and dental hypomineralization and episodes of apnea and vitamin B6-responsive seizures. Delay and defects in dentin mineralization, together with a deficiency in acellular cementum, are characteristic. We report the prevention of these dental abnormalities in Akp2-/- mice receiving treatment from birth with daily injections of a mineral-targeting, human TNALP (sALP-FcD10). sALP-FcD10 prevented hypomineralization of alveolar bone, dentin, and cementum as assessed by micro-computed tomography and histology. Osteopontin – a marker of acellular cementum – was immuno-localized along root surfaces, confirming that acellular cementum, typically missing or reduced in Akp2-/- mice, formed normally. Our findings provide insight concerning how acellular cementum is formed on tooth surfaces to effect periodontal ligament attachment to retain teeth in their osseous alveolar sockets. Furthermore, they provide evidence that this enzyme-replacement therapy, applied early in post-natal life – where the majority of tooth root development occurs, including acellular cementum formation – could prevent the accelerated tooth loss seen in individuals with HPP. PMID:21212313

Enzyme replacement therapy prevents dental defects in a model of hypophosphatasia.

PubMed

McKee, M D; Nakano, Y; Masica, D L; Gray, J J; Lemire, I; Heft, R; Whyte, M P; Crine, P; Millán, J L

2011-04-01

Hypophosphatasia (HPP) occurs from loss-of-function mutation in the tissue-non-specific alkaline phosphatase (TNALP) gene, resulting in extracellular pyrophosphate accumulation that inhibits skeletal and dental mineralization. TNALP-null mice (Akp2(-/-)) phenocopy human infantile hypophosphatasia; they develop rickets at 1 week of age, and die before being weaned, having severe skeletal and dental hypomineralization and episodes of apnea and vitamin B(6)-responsive seizures. Delay and defects in dentin mineralization, together with a deficiency in acellular cementum, are characteristic. We report the prevention of these dental abnormalities in Akp2(-/-) mice receiving treatment from birth with daily injections of a mineral-targeting, human TNALP (sALP-FcD(10)). sALP-FcD(10) prevented hypomineralization of alveolar bone, dentin, and cementum as assessed by micro-computed tomography and histology. Osteopontin--a marker of acellular cementum--was immuno-localized along root surfaces, confirming that acellular cementum, typically missing or reduced in Akp2(-/-) mice, formed normally. Our findings provide insight concerning how acellular cementum is formed on tooth surfaces to effect periodontal ligament attachment to retain teeth in their osseous alveolar sockets. Furthermore, they provide evidence that this enzyme-replacement therapy, applied early in post-natal life--where the majority of tooth root development occurs, including acellular cementum formation--could prevent the accelerated tooth loss seen in individuals with HPP.

Tooth wear in children: an investigation of etiological factors in children with cerebral palsy and gastroesophageal reflux.

PubMed

Shaw, L; Weatherill, S; Smith, A

1998-01-01

This investigation was undertaken to establish the prevalence and distribution of tooth wear in different groups of medically compromised children and to assess the possible influence of gastroesophageal reflux, dietary factors, and parafunctional activity. Four groups of children including twenty-one with cerebral palsy were clinically examined and had in-depth, structured interviews, including information on medical history, medication, gastroesophageal reflux, feeding and drinking habits, parafunctional activity, and tooth-brushing procedures. All the children with cerebral palsy also had twenty-four-hour gastroesophageal pH monitoring. Of the fifty-one children in total, twenty-five had moderate or severe levels of dental erosion. No statistically significant differences were found between the groups as far as dietary influences, feeding habits, and tooth-brushing procedures. There was a significant association, however, between gastroesophageal reflux and erosion. It is concluded that in children with cerebral palsy this reflux may be much more important in the etiology of tooth surface loss than the parafunctional activity, which has classically been regarded as the cause.

Tooth loss caused by displaced elastic during simple preprosthetic orthodontic treatment

PubMed Central

Dianiskova, Simona; Calzolari, Chiara; Migliorati, Marco; Silvestrini-Biavati, Armando; Isola, Gaetano; Savoldi, Fabio; Dalessandri, Domenico; Paganelli, Corrado

2016-01-01

The use of elastics to close a diastema or correct tooth malpositions can create unintended consequences if not properly controlled. The American Association of Orthodontists recently issued a consumer alert, warning of “a substantial risk for irreparable damage” from a new trend called “do-it-yourself” orthodontics, consisting of patients autonomously using elastics to correct tooth position. The elastics can work their way below the gums and around the roots of the teeth, causing damage to the periodontium and even resulting in tooth loss. The cost of implants to replace these teeth would well exceed the cost of proper orthodontic care. This damage could also occur in a dental office, when a general dentist tries to perform a simplified orthodontic correction of a minor tooth malposition. The present case report describes a case of tooth loss caused by a displaced intraoral elastic, which occurred during a simple preprosthetic orthodontic treatment. PMID:27672645

A 15-Year Time-series Study of Tooth Extraction in Brazil

PubMed Central

Cunha, Maria Aparecida Goncalves de Melo; Lino, Patrícia Azevedo; dos Santos, Thiago Rezende; Vasconcelos, Mara; Lucas, Simone Dutra; de Abreu, Mauro Henrique Nogueira Guimarães

2015-01-01

Abstract Tooth loss is considered to be a public health problem. Time-series studies that assess the influence of social conditions and access to health services on tooth loss are scarce. This study aimed to examine the time-series of permanent tooth extraction in Brazil between 1998 and 2012 and to compare these series in municipalities with different Human Development Index (HDI) scores and with different access to distinct primary and secondary care. The time-series study was performed between 1998 and 2012, using data from the Brazilian National Health Information System. Time-series study was performed between 1998 and 2012. Two annual rates of tooth extraction were calculated and evaluated separately according to 3 parameters: the HDI, the presence of a Dental Specialty Center, and coverage by Oral Health Teams. The time-series was analyzed using a linear regression model. An overall decrease in the tooth-loss tendencies during this period was observed, particularly in the tooth-extraction rate during primary care procedures. In the municipalities with an HDI that was lower than the median, the average tooth-loss rates were higher than in the municipalities with a higher HDI. The municipalities with lower rates of Oral Health Team coverage also showed lower extraction rates than the municipalities with higher coverage rates. In general, Brazil has shown a decrease in the trend to extract permanent teeth during these 15 years. Increased human development and access to dental services have influenced tooth-extraction rates. PMID:26632688

A new digitized reverse correction method for hypoid gears based on a one-dimensional probe

NASA Astrophysics Data System (ADS)

Li, Tianxing; Li, Jubo; Deng, Xiaozhong; Yang, Jianjun; Li, Genggeng; Ma, Wensuo

2017-12-01

In order to improve the tooth surface geometric accuracy and transmission quality of hypoid gears, a new digitized reverse correction method is proposed based on the measurement data from a one-dimensional probe. The minimization of tooth surface geometrical deviations is realized from the perspective of mathematical analysis and reverse engineering. Combining the analysis of complex tooth surface generation principles and the measurement mechanism of one-dimensional probes, the mathematical relationship between the theoretical designed tooth surface, the actual machined tooth surface and the deviation tooth surface is established, the mapping relation between machine-tool settings and tooth surface deviations is derived, and the essential connection between the accurate calculation of tooth surface deviations and the reverse correction method of machine-tool settings is revealed. Furthermore, a reverse correction model of machine-tool settings is built, a reverse correction strategy is planned, and the minimization of tooth surface deviations is achieved by means of the method of numerical iterative reverse solution. On this basis, a digitized reverse correction system for hypoid gears is developed by the organic combination of numerical control generation, accurate measurement, computer numerical processing, and digitized correction. Finally, the correctness and practicability of the digitized reverse correction method are proved through a reverse correction experiment. The experimental results show that the tooth surface geometric deviations meet the engineering requirements after two trial cuts and one correction.

Adult tooth loss for residents of US coal mining and Appalachian counties.

PubMed

Hendryx, Michael; Ducatman, Alan M; Zullig, Keith J; Ahern, Melissa M; Crout, Richard

2012-12-01

The authors compared rates of tooth loss between adult residents of Appalachian coal-mining areas and other areas of the nation before and after control for covariate risks. The authors conducted a cross-sectional secondary data analysis that merged 2006 national Behavioral Risk Factor Surveillance System data (BRFSS) (N = 242 184) with county coal-mining data and other county characteristics. The hypothesis tested was that adult tooth loss would be greater in Appalachian mining areas after control for other risks. Primary independent variables included main effects for coal-mining present (yes/no) residence in Appalachia (yes/no), and their interaction. Data were weighted using the BRFSS final weights and analyzed using SUDAAN Proc Multilog to account for the multilevel complex sampling structure. The odds of two measures of tooth loss were examined controlling for age, race\\ethnicity, drinking, smoking, income, education, supply of dentists, receipt of dental care, fluoridation rate, and other variables. After covariate adjustment, the interaction variable for the residents of Appalachian coal-mining counties showed a significantly elevated odds for any tooth loss [odds ratio (OR) = 1.19, 95% CI = 1.02, 1.38], and greater tooth loss measured by a 4-level edentulism scale (OR = 1.20, 95% CI = 1.05, 1.36). The main effect for Appalachia was also significant for both measures, but the main effect for coal mining was not. Greater risk of tooth loss among adult residents of Appalachian coal-mining areas is present and is not explained by differences in reported receipt of dental care, fluoridation rates, supply of dentists or other behavioral or socioeconomic risks. Possible contributing factors include mining-specific disparities related to access, behavior or environmental exposures. © 2012 John Wiley & Sons A/S.

Compliance as a prognostic indicator. II. Impact of patient's compliance to the individual tooth survival.

PubMed

Miyamoto, Takanari; Kumagai, Takashi; Lang, Melissa S; Nunn, Martha E

2010-09-01

Existing evidence concerning the validity of an appropriate regular periodontal maintenance (PM) regimen and the role of patient compliance is controversial and inconsistent. The objectives of this study are to identify the impact of patient compliance (complete versus erratic) on alveolar bone loss and tooth survival. A retrospective study was conducted using data from 295 patients with >or=20 years of observation, which included treatment and >or=15 years of maintenance therapy, in a private practice in Yamagata, Japan. Subject-level variables and tooth-level variables were recorded at the initial visit, the reevaluation visit, and the final visit. In total, 7,502 teeth in 295 subjects met inclusion criteria and were divided into two groups: non-molar teeth (n = 5,585) and molar teeth (n = 1,917). A tooth-level multivariate survival model and multiple logistic regression model using the method of generalized estimating equations were constructed to analyze the effects of compliance and periodontal maintenance intervals on tooth loss and alveolar bone loss, respectively. Of 7,502 teeth, 284 molar teeth and 364 non-molar teeth were lost. Molar teeth had an approximately 30% reduction in risk of tooth loss for complete compliance, with 2-year compliance classification achieving statistical significance (P = 0.033), and 30% compliance classification approaching statistical significance (P = 0.072). Complete compliers under 30% compliance classification showed over 50% reduction in the risk of alveolar bone loss among non-molars (P = 0.015). Complete patient compliance with increased frequency of periodontal maintenance is important for improved dental prognosis through reduction of tooth loss among molars and minimization of alveolar bone loss among non-molars.

Tooth loss in well-maintained patients with chronic periodontitis during long-term supportive therapy in Brazil.

PubMed

Chambrone, Luiz A; Chambrone, Leandro

2006-10-01

The objective of this retrospective study was to assess the reasons for tooth loss in a sample of patients who underwent periodontal therapy and supportive periodontal therapy (SPT) in a Brazilian private periodontal practice. A sample of 120 subjects who had been treated and maintained for 10 years or longer was selected from patients attending a periodontal practice. All patients followed a similar treatment: basic procedures, re-evaluation and periodontal surgery where indicated. Reasons for tooth loss were categorized as periodontal, caries, endodontal, root fractures and extraction of retained or partially erupted third molars. Of the 2927 teeth present at the completion of active periodontal treatment, 53 (1.8%) were lost due to periodontal disease, 16 (0.5%) for root fracture, six (0.2%) to caries, five (0.2%) for endodontic reasons and 31 (1.0%) were lost to extraction of retained or partially erupted third molars. Logistic regression analysis was performed to investigate the association between five independent variables with tooth loss due to periodontitis. Only age (> 60 years) and smoking were statistically significant (p < 0.05). The findings of this survey were consistent with previous studies. Older subjects and smokers were more susceptible to periodontal tooth loss. In addition, patients with generalized chronic periodontitis were treated and maintained for long-term periods with low rates of tooth loss.

Craniomandibular Trauma and Tooth Loss in Northern Dogs and Wolves: Implications for the Archaeological Study of Dog Husbandry and Domestication

PubMed Central

Losey, Robert J.; Jessup, Erin; Nomokonova, Tatiana; Sablin, Mikhail

2014-01-01

Archaeological dog remains from many areas clearly show that these animals suffered tooth fractures, tooth loss, trauma, and dental defects during their lives. Relatively little research has explored the meanings of these patterns, particularly for ancient dog remains from small-scale societies of the North. One limiting issue is the lack of comparative data on dental health and experiences of trauma among northern wolves and dogs. This paper examines tooth loss, tooth fracture, enamel hypoplasia, and cranial trauma in a large sample of historic dog and wolf remains from North America and Northern Russia. The data indicate that the dogs more commonly experienced tooth loss and tooth fracture than the wolves, despite reportedly being fed mostly soft foods such as blubber and fish. The higher rates observed in the dogs likely is a result of food stress and self-provisioning through scavenging. The ability to self-provision was likely important for the long-term history of dog use in the north. Dogs also more commonly experienced cranial fractures than wolves, particularly depression fractures on their frontal bones, which were likely the result of blows from humans. Hypoplastic lesions are rare in both wolves and dogs, and probably result from multiple causes, including food stress, disease, and trauma. PMID:24941003

Craniomandibular trauma and tooth loss in northern dogs and wolves: implications for the archaeological study of dog husbandry and domestication.

PubMed

Losey, Robert J; Jessup, Erin; Nomokonova, Tatiana; Sablin, Mikhail

2014-01-01

Archaeological dog remains from many areas clearly show that these animals suffered tooth fractures, tooth loss, trauma, and dental defects during their lives. Relatively little research has explored the meanings of these patterns, particularly for ancient dog remains from small-scale societies of the North. One limiting issue is the lack of comparative data on dental health and experiences of trauma among northern wolves and dogs. This paper examines tooth loss, tooth fracture, enamel hypoplasia, and cranial trauma in a large sample of historic dog and wolf remains from North America and Northern Russia. The data indicate that the dogs more commonly experienced tooth loss and tooth fracture than the wolves, despite reportedly being fed mostly soft foods such as blubber and fish. The higher rates observed in the dogs likely is a result of food stress and self-provisioning through scavenging. The ability to self-provision was likely important for the long-term history of dog use in the north. Dogs also more commonly experienced cranial fractures than wolves, particularly depression fractures on their frontal bones, which were likely the result of blows from humans. Hypoplastic lesions are rare in both wolves and dogs, and probably result from multiple causes, including food stress, disease, and trauma.

Investigations Into Age-related Changes in the Human Mandible.

PubMed

Parr, Nicolette M; Passalacqua, Nicholas V; Skorpinski, Katie

2017-11-01

While changes in mandibular shape over time are not widely recognized by skeletal biologists, mandibular remodeling and associated changes in gross morphology may result from a number of causes related to mechanical stress such as antemortem tooth loss, changes in bite force, or alterations of masticatory performance. This study investigated the relationship between age-related changes and antemortem tooth loss in adult humans via dry bone measurements. This study examined 10 standard mandibular measurements as well as individual antemortem tooth loss scores using the Eichner Index from a total of 319 female and male individuals with ages ranging from 16 to 99 years. Results indicate that few mandibular measurements exhibited age-related changes, and most were affected by antemortem tooth loss. © 2017 American Academy of Forensic Sciences.

Analysis of enamel surface damage after selective laser ablation of composite from tooth surfaces.

PubMed

Chan, Kenneth H; Hirasuna, Krista; Fried, Daniel

2014-02-01

Resin-based composites are used for many applications in dentistry. They are difficult to remove without damage to the underlying enamel since they adhere strongly and are color matched to the tooth. The objective of this study was to determine if an automated laser scanning system with spectral feedback could be used for selective removal of residual orthodontic composite from tooth surfaces with minimal damage to the underlying enamel. A CO 2 laser operating at a wavelength of 9.3 μm with a pulse duration of 10-15 μs and a pulse repetition rate of ~200 Hz was used to selectively remove composite from the buccal surfaces of extracted teeth. A spectral feedback system utilizing a miniature spectrometer was used to control the laser scanning system. Pulpal temperature measurements were performed during composite removal to determine if there was excessive heat accumulation. Conventional and digital microscopes were used to assess the amount of enamel lost during removal. The amount of enamel lost averaged between 20 and 25 μm for irradiation intensities from 3.8 to 4.2 J/cm 2 , respectively. An average maximum temperature rise of 1.9±1.5°C was recorded, with no teeth approaching the critical value of 5.5°C. The average time for composite removal from an area of 5 mm 2 was 19.3±4.1 s, fast enough for clinical feasibility. Residual composite can be rapidly removed from tooth surfaces using a CO 2 laser with spectral feedback, with minimal temperature rise within the pulp and with minimal loss of sound enamel.

FACTORS RELATED TO TOOTH LOSS AMONG INDUSTRIAL WORKERS IN PHATHUM THANI, THAILAND.

PubMed

Jaaidee, Jeerateep; Chatrchaiwiwatana, Supaporn; Ratanasiri, Amornrat

2017-01-01

Tooth loss is an important oral health problem among Thai people. The objectives of this study were to evaluate the prevalence of and factors associated with tooth loss among Thai industrial workers in order to apply preventive oral health programs to this population. The study consisted of 1,500 adults working in Nava Nakorn Industrial Estate, Pathum Thani Province, Thailand in 2014. Probability proportion to size cluster sampling was used and 16 clusters were included in the study. An oral health questionnaire was developed, evaluated for content validity by experts and then given to participants to fill out. The study population consisted of 621 males (41.4%) and 879 females (58.6%) aged between 19-25 years. The overall prevalence of tooth loss was 62.2% and the major reason for tooth loss was dental caries (60%). Results from multivariable logistic regression analysis show that factors associated with tooth loss were: having a history of scaling or tooth cleaning [adjusted odds ratio (AOR)= 2.47; 95% CI: 1.21-4.65], having dental caries with exposed pulp (AOR=4.12; 95% CI: 3.26-7.67), having tooth mobility due to periodontal disease (AOR=2.41; 95% CI: 2.71-5.22), having needed tooth restoration (AOR=1.75; 95% CI: 1.23-2.65), having a history of maxillofacial or a temporo-mandibular joint accident (AOR=2.13; 95% CI: 1.87- 3.23), wearing dentures (AOR=2.58; 95% CI: 2.17-6.72), using dental care services during the previous year (AOR=2.21; 95% CI: 1.26-4.57), eating snacks and candy daily (AOR=2.14; 95% CI: 1.82-2.92), having toothache (AOR=2.64; 95% CI: 1.43- 3.92), having dental caries (AOR=2.23; 95% CI: 1.62-3.27) and having a history of orthodontic treatment (AOR=3.61; 95% CI: 1.84-5.68). The Nagelkerke R squared for the model was 0.42. Our findings suggest several clinical, socio-economic and lifestyle factors are associated with tooth loss among these Thai industrial workers. An appropriate preventive oral health program targeting this high-risk group taking these factors into consideration needs to be developed and implemented in this at risk population.

Neutrophil mobilization by surface-glycan altered Th17-skewing bacteria mitigates periodontal pathogen persistence and associated alveolar bone loss.

PubMed

Settem, Rajendra P; Honma, Kiyonobu; Sharma, Ashu

2014-01-01

Alveolar bone (tooth-supporting bone) erosion is a hallmark of periodontitis, an inflammatory disease that often leads to tooth loss. Periodontitis is caused by a select group of pathogens that form biofilms in subgingival crevices between the gums and teeth. It is well-recognized that the periodontal pathogen Porphyromonas gingivalis in these biofilms is responsible for modeling a microbial dysbiotic state, which then initiates an inflammatory response destructive to the periodontal tissues and bone. Eradication of this pathogen is thus critical for the treatment of periodontitis. Previous studies have shown that oral inoculation in mice with an attenuated strain of the periodontal pathogen Tannerella forsythia altered in O-glycan surface composition induces a Th17-linked mobilization of neutrophils to the gingival tissues. In this study, we sought to determine if immune priming with such a Th17-biasing strain would elicit a productive neutrophil response against P. gingivalis. Our data show that inoculation with a Th17-biasing T. forsythia strain is effective in blocking P. gingivalis-persistence and associated alveolar bone loss in mice. This work demonstrates the potential of O-glycan modified Tannerella strains or their O-glycan components for harnessing Th17-mediated immunity against periodontal and other mucosal pathogens.

Nonlinear dynamic model of a gear-rotor-bearing system considering the flash temperature

NASA Astrophysics Data System (ADS)

Gou, Xiangfeng; Zhu, Lingyun; Qi, Changjun

2017-12-01

The instantaneous flash temperature is an important factor for gears in service. To investigate the effect of the flash temperature of a tooth surface on the dynamics of the spur gear system, a modified nonlinear dynamic model of a gear-rotor-bearing system is established. The factors such as the contact temperature of the tooth surface, time-varying stiffness, tooth surface friction, backlash, the comprehensive transmission error and so on are considered. The flash temperature of a tooth surface of pinion and gear is formulated according to Blok's flash temperature theory. The mathematical expression of the contact temperature of the tooth surface varied with time is derived and the tooth profile deformation caused by the change of the flash temperature of the tooth surface is calculated. The expression of the mesh stiffness varied with the flash temperature of the tooth surface is derived based on Hertz contact theory. The temperature stiffness is proposed and added to the nonlinear dynamic model of the system. The influence of load on the flash temperature of the tooth surface is analyzed in the parameters plane. The variation of the flash temperature of the tooth surface is studied. The numerical results indicate that the calculated method of the flash temperature of the gear tooth surface is effective and it can reflect the rules for the change of gear meshing temperature and sliding of the gear tooth surface. The effects of frequency, backlash, bearing clearance, comprehensive transmission error and time-varying stiffness on the nonlinear dynamics of the system are analyzed according to the bifurcation diagrams, Top Lyapunov Exponent (TLE) spectrums, phase portraits and Poincaré maps. Some nonlinear phenomena such as periodic bifurcation, grazing bifurcation, quasi-periodic bifurcation, chaos and its routes to chaos are investigated and the critical parameters are identified. The results provide an understanding of the system and serve as a useful reference in designing such systems.

The role of potential mediators in racial inequalities in tooth loss: the Pró-Saúde study.

PubMed

Celeste, Roger Keller; Gonçalves, Letícia Gomes; Faerstein, Eduardo; Bastos, João Luiz

2013-12-01

To assess the relation between race and tooth loss, as well as the influence of socioeconomic factors, health behaviours, routine dental care and self-reported discrimination on this association. This is a cross-sectional study with data collected from the baseline of the Pró-Saúde Study (Rio de Janeiro/Brazil), among 3253 civil servants in 1999-2001. Race was measured as self-reported skin colour (Black/Brown/White). The outcome was self-reported tooth loss, measured in four ordered categories (none/one or few/many/all or almost all). Three mediating pathways were explored between race and tooth loss. The first included self-reported discrimination assessed with a five-item scale. The second pathway included behavioural factors: routine dental care, marital status, smoking and alcohol consumption. The third considered socioeconomic factors: income, education, maternal education and early life poverty. Confounding factors were age and sex. Statistical analyses were carried out with ordinal logistic regression. Absence of all or almost all teeth was reported by 8% of respondents. White individuals comprised 53% of the population, followed by Browns (26%) and Blacks (22%). After adjustment, Blacks had an odds ratio of being in a higher category of missing teeth equal to 1.39 (95% CI 1.12-1.72), and Browns, 1.33 (95% CI 1.10-1.60), when compared to Whites. Age, sex and socioeconomic variables explained most of racial inequalities in tooth loss, while behavioural and discrimination variables contributed very little. Behavioural and socioeconomic variables were associated with tooth loss, while discrimination was not. No statistically significant interactions were found. There is an association between race and tooth loss that is mainly explained by current and early life socioeconomic variables, but not by behavioural factors and self-reported discrimination. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The long-term effect of a plaque control program on tooth mortality, caries and periodontal disease in adults. Results after 30 years of maintenance.

PubMed

Axelsson, P; Nyström, B; Lindhe, J

2004-09-01

The biofilm that forms and remains on tooth surfaces is the main etiological factor in caries and periodontal disease. Prevention of caries and periodontal disease must be based on means that counteract this bacterial plaque. To monitor the incidence of tooth loss, caries and attachment loss during a 30-year period in a group of adults who maintained a carefully managed plaque control program. In addition, a comparison was made regarding the oral health status of individuals who, in 1972 and 2002, were 51-65 years old. In 1971 and 1972, more than 550 subjects were recruited. Three hundred and seventy-five subjects formed a test group and 180 a control group. After 6 years of monitoring, the control group was discontinued but the participants in the test group was maintained in the preventive program and was finally re-examined after 30 years. The following variables were studied at Baseline and after 3, 6, 15 and 30 years: plaque, caries, probing pocket depth, probing attachment level and CPITN. Each patient was given a detailed case presentation and education in self-diagnosis. Once every 2 months during the first 2 years, once every 3-12 months during years 3-30, the participants received, on an individual need basis, additional education in self-diagnosis and self-care focused on proper plaque control measures, including the use of toothbrushes and interdental cleaning devices (brush, dental tape, toothpick). The prophylactic sessions that were handled by a dental hygienist also included (i) plaque disclosure and (ii) professional mechanical tooth cleaning including the use of a fluoride-containing dentifrice/paste. Few teeth were lost during the 30 years of maintenance; 0.4-1.8 in different age cohorts. The main reason for tooth loss was root fracture; only 21 teeth were lost because of progressive periodontitis or caries. The mean number of new caries lesions was 1.2, 1.7 and 2.1 in the three groups. About 80% of the lesions were classified as recurrent caries. Most sites, buccal sites being the exception, exhibited no sign of attachment loss. Further, on approximal surfaces there was some gain of attachment between 1972 and 2002 in all age groups. The present study reported on the 30-year outcome of preventive dental treatment in a group of carefully monitored subjects who on a regular basis were encouraged, but also enjoyed and recognized the benefit of, maintaining a high standard of oral hygiene. The incidence of caries and periodontal disease as well as tooth mortality in this subject sample was very small. Since all preventive and treatment efforts during the 30 years were delivered in one private dental office, caution must be exercised when comparisons are made with longitudinal studies that present oral disease data from randomly selected subject samples.

Assessing the effects of tooth loss in adult crania using geometric morphometrics.

PubMed

Small, Candice; Brits, Desiré; Hemingway, Jason

2016-01-01

With high numbers of unidentified skeletonised remains recovered annually in South Africa and an increased number of edentate individuals being reported, the question arises as to whether tooth loss would result in craniofacial changes which might alter the accuracy of osteological analyses. Forty-five fixed landmarks together with sliding semilandmarks were collected from 229 white South African crania and were used to capture curve data pertaining to the basicranium, alveoli, zygomatic arches, nasal aperture and orbits. Geometric morphometric methods were employed to assess the effects of tooth loss on these structures. Although a number of effects were seen when the skull was analysed in its entirety, only the alveoli proved to be significantly affected when regions were analysed individually. Both upper facial height and palate shape were affected by tooth loss, which may influence various osteometric measurements and qualitative traits that are used during the assessment of ancestry and sex.

Evaluation of the mineralization degree of the vestibular surface of the upper central incisors with a 655-nm diode laser in mouth breathers: preliminary results

NASA Astrophysics Data System (ADS)

Pinheiro Ladalardo, Thereza C. C. G.; Cappellette, Mario, Jr.; Zanin, Fatima A. A.; Brugnera, Aldo, Jr.; Anthero de Azevedo, Ramiro; Pignatari, Shirley; Weckx, Luc L. M.

2003-06-01

Mouth breathing unbalances the physiological mechanisms of the dental surface hydration by compromising lip closure, and, very often, causing the vestibular positioning of upper incisors. That variance leads to the interruption of the dental demineralization and remineralization feedback, prevailing a demineralized condition of the dental surface which increases caries risk. The laser fluorescence examination allows an early demineralization diagnosis, thus it makes possible through preventive measures to minimize the risk factor - dental mineral structure loss - in the bacterial infection of the demineralized area, and hence, preventing invasive therapeutical procedures. A DIAGNOdent apparatus was used to evaluate the mineralization degree of the upper central incisors in 40 patients - twenty of them with a mouth breathing diagnosis; the remaining twenty were nasal breathers (control group). Age ranging from 6 to 12 years, both male and female. To measure the vestibular surface of the incisors, it was divided into 3 segments: cervical, medial and incisal. The average of the results pertaining to the mouth breathing patients was as follows: tooth 11 cervical third - 5.45, medial third - 7.15, incisal third - 7.95, and tooth 21 - cervical third - 5.95, medial third - 7.25, incisal third - 8.15. The control patients, nasal breathers, presented the following results: tooth 11 cervical third - 1.75, medial third - 2.30, incisal third - 1.85, and tooth 21 - cervical third - 1.80, medial third - 2.20, incisal third - 2.15. The mouth breathing patients showed demineralization in the teeth examined at the initial stage, subclinical, comparing with the control patients, nasal breathers, who did not present any mineral deficit in these teeth.

Survival rates and bone loss after immediate loading of implants in fresh extraction sockets (single gaps). A clinical prospective study with 4 year follow-up

PubMed Central

Wojtovicz, Eduardo; España-Lopez, Antonio; Jimenez-Guerra, Alvaro; Monsalve-Guil, Loreto; Ortiz-Garcia, Ivan; Serrera-Figallo, Maria-Angeles

2018-01-01

Background The aim of this prospective study was to report the outcome of treatment with implants inserted after tooth extraction and immediately loaded. Material and Methods Fifty-six patients with single tooth loss were treated with 116 IPX Galimplant® implants with internal connections and a sandblasted, acid-etched surface. All implants were placed after tooth extraction using a flapless approach without bone regeneration, and they were then immediately loaded with cemented acrylic prostheses. After a period of three months, definitive cemented ceramic prostheses were placed. Patients were examined throughout a total of 4 years of follow-up. Marginal bone loss and survival rates were evaluated using digital periapical radiographs, taking into account clinical variables such as age, gender, smoking, history of periodontitis, etiology of extraction, placement site, diameter, and implant length. The Mann-Whitney U and Kruskal-Wallis non-parametric tests were used to compare differences between subgroups created based on the different clinical variables identified. Results Clinical results indicate an implant survival and success rate of 97.4%. Three implants were lost. Of the 116 immediate acrylic single crowns initially placed, 113 were replaced with definitive ceramic crowns after 3 months. A total of 77.8% of implants were inserted in the maxilla, while 22.2% were inserted in the mandible. No further complications were reported after the follow-up period (4 years). The mean marginal bone loss was 0.67 mm ± 0.40 mm. No differences were found among the subgroups of study patients. Conclusions This study indicates that dental implants that are inserted after tooth extraction and immediately loaded may constitute a successful and predictable alternative implant treatment. Key words:Dental implants, post-extraction implants, fresh sockets, immediate loading, immediate prostheses, implant dentistry. PMID:29476669

Reverse engineering of machine-tool settings with modified roll for spiral bevel pinions

NASA Astrophysics Data System (ADS)

Liu, Guanglei; Chang, Kai; Liu, Zeliang

2013-05-01

Although a great deal of research has been dedicated to the synthesis of spiral bevel gears, little related to reverse engineering can be found. An approach is proposed to reverse the machine-tool settings of the pinion of a spiral bevel gear drive on the basis of the blank and tooth surface data obtained by a coordinate measuring machine(CMM). Real tooth contact analysis(RTCA) is performed to preliminary ascertain the contact pattern, the motion curve, as well as the position of the mean contact point. And then the tangent to the contact path and the motion curve are interpolated in the sense of the least square method to extract the initial values of the bias angle and the higher order coefficients(HOC) in modified roll motion. A trial tooth surface is generated by machine-tool settings derived from the local synthesis relating to the initial meshing performances and modified roll motion. An optimization objective is formed which equals the tooth surface deviation between the real tooth surface and the trial tooth surface. The design variables are the parameters describing the meshing performances at the mean contact point in addition to the HOC. When the objective is optimized within an arbitrarily given convergence tolerance, the machine-tool settings together with the HOC are obtained. The proposed approach is verified by a spiral bevel pinion used in the accessory gear box of an aviation engine. The trial tooth surfaces approach to the real tooth surface on the whole in the example. The results show that the convergent tooth surface deviation for the concave side on the average is less than 0.5 μm, and is less than 1.3 μm for the convex side. The biggest tooth surface deviation is 6.7 μm which is located at the corner of the grid on the convex side. Those nodes with relative bigger tooth surface deviations are all located at the boundary of the grid. An approach is proposed to figure out the machine-tool settings of a spiral bevel pinion by way of reverse engineering without having known the theoretical tooth surfaces and the corresponding machine-tool settings.

The association between depression and anxiety and use of oral health services and tooth loss.

PubMed

Okoro, Catherine A; Strine, Tara W; Eke, Paul I; Dhingra, Satvinder S; Balluz, Lina S

2012-04-01

The purpose of this study is to examine the associations among depression, anxiety, use of oral health services, and tooth loss. Data were analysed for 80 486 noninstitutionalized adults in 16 states who participated in the 2008 Behavioral Risk Factor Surveillance System. Binomial and multinomial logistic regression analyses were used to estimate predicted marginals, adjusted prevalence ratios, adjusted odds ratios (AOR) and their 95% confidence intervals (CI). The unadjusted prevalence for use of oral health services in the past year was 73.1% [standard error (SE), 0.3%]. The unadjusted prevalence by level of tooth loss was 56.1% (SE, 0.4%) for no tooth loss, 29.6% (SE, 0.3%) for 1-5 missing teeth, 9.7% (SE, 0.2%) for 6-31 missing teeth and 4.6% (SE, 0.1%) for total tooth loss. Adults with current depression had a significantly higher prevalence of nonuse of oral health services in the past year than those without this disorder (P < 0.001), after adjustment for age, sex, race/ethnicity, education, marital status, employment status, adverse health behaviours, chronic conditions, body mass index, assistive technology use and perceived social support. In logistic regression analyses employing tooth loss as a dichotomous outcome (0 versus ≥1) and as a nominal outcome (0 versus 1-5, 6-31, or all), adults with depression and anxiety were more likely to have tooth loss. Adults with current depression, lifetime diagnosed depression and lifetime diagnosed anxiety were significantly more likely to have had at least one tooth removed than those without each of these disorders (P < 0.001 for all), after fully adjusting for evaluated confounders (including use of oral health services). The adjusted odds of being in the 1-5 teeth removed, 6-31 teeth removed, or all teeth removed categories versus 0 teeth removed category were increased for adults with current depression versus those without (AOR = 1.35; 95% CI = 1.14-1.59; AOR = 1.83; 95% CI = 1.51-2.22; and AOR = 1.44; 95% CI = 1.11-1.86, respectively). The adjusted odds of being in the 1-5 teeth removed and 6-31 teeth removed categories versus 0 teeth removed category were also increased for adults with lifetime diagnosed depression or anxiety versus those without each of these disorders. Use of oral health services and tooth loss was associated with depression and anxiety after controlling for multiple confounders. © 2011 John Wiley & Sons A/S.

Efficacy of the Nance appliance as an anchorage-reinforcement method.

PubMed

Al-Awadhi, Ebrahim A; Garvey, Therese M; Alhag, Mohamed; Claffey, Noel M; O'Connell, Brian

2015-03-01

The Nance appliance is widely considered to be an efficient method of anchorage reinforcement; however, much of the perceived advantage is based on clinical judgment. The aim of this study was to assess the amounts of anchorage loss and desired tooth movement associated with the Nance appliance. The mandibular arches of 7 beagle dogs were used. The first and third premolars were extracted. Reference miniscrews were placed at the first premolar sites as stable references to measure the amounts of anchorage loss and desired tooth movement. Four beagles were fitted with custom-made Nance appliances on the fourth premolars and orthodontic bands on the second premolars (Nance group). Three beagles were fitted with orthodontic bands on the second and fourth premolars with no anchorage reinforcement (control group). The second premolars were retracted over 15 weeks in both groups. The amounts of second premolar movement (desired tooth movement) and fourth premolar movement (anchorage loss) were recorded at 5, 10, and 15 weeks. The percentages of desired tooth movement and anchorage loss to the total space closure were calculated. The mean desired tooth movement was significantly more in the Nance group than in the control group at 10 weeks (P <0.05) but was not significantly different at 5 and 15 weeks. The mean percentages of anchorage loss to the total space closure at 15 weeks were 45.7% in the control group and 28.8% in the Nance group. The Nance group had 16.9% less anchorage loss and 16.6% more desired tooth movement than did the control group at 15 weeks (P <0.05). Most of the anchorage loss (80%) in the Nance group occurred during the first 10 weeks. The Nance appliance did not provide absolute anchorage, but there was significantly less anchorage loss with it than in the control group. The majority of anchorage loss occurred during the first 10 weeks in the Nance group. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

A Biofilm Pocket Model to Evaluate Different Non-Surgical Periodontal Treatment Modalities in Terms of Biofilm Removal and Reformation, Surface Alterations and Attachment of Periodontal Ligament Fibroblasts

PubMed Central

Hägi, Tobias T.; Klemensberger, Sabrina; Bereiter, Riccarda; Nietzsche, Sandor; Cosgarea, Raluca; Flury, Simon; Lussi, Adrian; Sculean, Anton; Eick, Sigrun

2015-01-01

Background and Aim There is a lack of suitable in vitro models to evaluate various treatment modalities intending to remove subgingival bacterial biofilm. Consequently, the aims of this in vitro-study were: a) to establish a pocket model enabling mechanical removal of biofilm and b) to evaluate repeated non-surgical periodontal treatment with respect to biofilm removal and reformation, surface alterations, tooth hard-substance-loss, and attachment of periodontal ligament (PDL) fibroblasts. Material and Methods Standardized human dentin specimens were colonized by multi-species biofilms for 3.5 days and subsequently placed into artificially created pockets. Non-surgical periodontal treatment was performed as follows: a) hand-instrumentation with curettes (CUR), b) ultrasonication (US), c) subgingival air-polishing using erythritol (EAP) and d) subgingival air-polishing using erythritol combined with chlorhexidine digluconate (EAP-CHX). The reduction and recolonization of bacterial counts, surface roughness (Ra and Rz), the caused tooth substance-loss (thickness) as well as the attachment of PDL fibroblasts were evaluated and statistically analyzed by means of ANOVA with Post-Hoc LSD. Results After 5 treatments, bacterial reduction in biofilms was highest when applying EAP-CHX (4 log10). The lowest reduction was found after CUR (2 log10). Additionally, substance-loss was the highest when using CUR (128±40 µm) in comparison with US (14±12 µm), EAP (6±7 µm) and EAP-CHX (11±10) µm). Surface was roughened when using CUR and US. Surfaces exposed to US and to EAP attracted the highest numbers of PDL fibroblasts. Conclusion The established biofilm model simulating a periodontal pocket combined with interchangeable placements of test specimens with multi-species biofilms enables the evaluation of different non-surgical treatment modalities on biofilm removal and surface alterations. Compared to hand instrumentation the application of ultrasonication and of air-polishing with erythritol prevents from substance-loss and results in a smooth surface with nearly no residual biofilm that promotes the reattachment of PDL fibroblasts. PMID:26121365

A Biofilm Pocket Model to Evaluate Different Non-Surgical Periodontal Treatment Modalities in Terms of Biofilm Removal and Reformation, Surface Alterations and Attachment of Periodontal Ligament Fibroblasts.

PubMed

Hägi, Tobias T; Klemensberger, Sabrina; Bereiter, Riccarda; Nietzsche, Sandor; Cosgarea, Raluca; Flury, Simon; Lussi, Adrian; Sculean, Anton; Eick, Sigrun

2015-01-01

There is a lack of suitable in vitro models to evaluate various treatment modalities intending to remove subgingival bacterial biofilm. Consequently, the aims of this in vitro-study were: a) to establish a pocket model enabling mechanical removal of biofilm and b) to evaluate repeated non-surgical periodontal treatment with respect to biofilm removal and reformation, surface alterations, tooth hard-substance-loss, and attachment of periodontal ligament (PDL) fibroblasts. Standardized human dentin specimens were colonized by multi-species biofilms for 3.5 days and subsequently placed into artificially created pockets. Non-surgical periodontal treatment was performed as follows: a) hand-instrumentation with curettes (CUR), b) ultrasonication (US), c) subgingival air-polishing using erythritol (EAP) and d) subgingival air-polishing using erythritol combined with chlorhexidine digluconate (EAP-CHX). The reduction and recolonization of bacterial counts, surface roughness (Ra and Rz), the caused tooth substance-loss (thickness) as well as the attachment of PDL fibroblasts were evaluated and statistically analyzed by means of ANOVA with Post-Hoc LSD. After 5 treatments, bacterial reduction in biofilms was highest when applying EAP-CHX (4 log10). The lowest reduction was found after CUR (2 log10). Additionally, substance-loss was the highest when using CUR (128±40 µm) in comparison with US (14±12 µm), EAP (6±7 µm) and EAP-CHX (11±10) µm). Surface was roughened when using CUR and US. Surfaces exposed to US and to EAP attracted the highest numbers of PDL fibroblasts. The established biofilm model simulating a periodontal pocket combined with interchangeable placements of test specimens with multi-species biofilms enables the evaluation of different non-surgical treatment modalities on biofilm removal and surface alterations. Compared to hand instrumentation the application of ultrasonication and of air-polishing with erythritol prevents from substance-loss and results in a smooth surface with nearly no residual biofilm that promotes the reattachment of PDL fibroblasts.

Clinical success of implant-supported and tooth-implant-supported double crown-retained dentures.

PubMed

Bernhart, Gunda; Koob, Andreas; Schmitter, Marc; Gabbert, Olaf; Stober, Thomas; Rammelsberg, Peter

2012-08-01

The objective of this retrospective study was to compare biological and technical complications of implant-supported and tooth-implant-supported double crown-retained dentures (DCRDs) with those of tooth-supported DCRDs. Sixty-three DCRDs were monitored. One study group included 16 prostheses with a combination of implants and natural teeth as double crowns (ti group), whereas in the second study group, 19 dentures were retained exclusively on implants (ii group); a third study group with 28 exclusively tooth-supported dentures served as controls (tt group). Tooth loss, implant failure, and technical complications (loss of retention of primary crown, abutment screw loosening, loss of facing, fracture of resin denture teeth and fracture of saddle resin) were analysed. During the observation period of 24 months, no implants or teeth were lost in the ti group and three technical complications were recorded. In the ii group, two implants were lost, two cases of peri-implantitis occurred and four technical complications were observed. In the tt group, two cases of tooth loss and seven technical complications were observed. At the time of the last examination, all prostheses of the ti group and the ii group were functional. Patients of these two study groups reported high satisfaction with both function and aesthetics with no significant difference between the two groups. Treatment with DCRDs showed comparable results in the three study groups. The 2-year results indicate that double crowns can be recommended for implant and combined tooth-implant-retained dentures.

Dental Care in Pregnancy

MedlinePlus

... protective) coating on your teeth, which can cause tooth decay (cavities) or even tooth loss. Periodontal disease can ... prevent plaque buildup, which causes gum disease and tooth decay. Use a soft-bristled toothbrush because your gums ...

Making teeth to order: conserved genes reveal an ancient molecular pattern in paddlefish (Actinopterygii)

PubMed Central

Smith, Moya M.; Johanson, Zerina; Butts, Thomas; Ericsson, Rolf; Modrell, Melinda; Tulenko, Frank J.; Davis, Marcus C.; Fraser, Gareth J.

2015-01-01

Ray-finned fishes (Actinopterygii) are the dominant vertebrate group today (+30 000 species, predominantly teleosts), with great morphological diversity, including their dentitions. How dental morphological variation evolved is best addressed by considering a range of taxa across actinopterygian phylogeny; here we examine the dentition of Polyodon spathula (American paddlefish), assigned to the basal group Acipenseriformes. Although teeth are present and functional in young individuals of Polyodon, they are completely absent in adults. Our current understanding of developmental genes operating in the dentition is primarily restricted to teleosts; we show that shh and bmp4, as highly conserved epithelial and mesenchymal genes for gnathostome tooth development, are similarly expressed at Polyodon tooth loci, thus extending this conserved developmental pattern within the Actinopterygii. These genes map spatio-temporal tooth initiation in Polyodon larvae and provide new data in both oral and pharyngeal tooth sites. Variation in cellular intensity of shh maps timing of tooth morphogenesis, revealing a second odontogenic wave as alternate sites within tooth rows, a dental pattern also present in more derived actinopterygians. Developmental timing for each tooth field in Polyodon follows a gradient, from rostral to caudal and ventral to dorsal, repeated during subsequent loss of teeth. The transitory Polyodon dentition is modified by cessation of tooth addition and loss. As such, Polyodon represents a basal actinopterygian model for the evolution of developmental novelty: initial conservation, followed by tooth loss, accommodating the adult trophic modification to filter-feeding. PMID:25788604

Tooth wear and erosion: methodological issues in epidemiological and public health research and the future research agenda.

PubMed

Ganss, C; Young, A; Lussi, A

2011-09-01

This paper addresses methodological issues in the field of tooth wear and erosion research including the epidemiological indices, and identifies future work that is needed to improve knowledge about tooth wear and erosion. The paper is result of the work done at the meetings of the Special Interest Group "Tooth Surface Loss and Erosion" at the 2008, 2009 and 2010 conferences of the European Association for Dental Public Health, and the Workshop "Current Erosion indices- flawed or valid" which took place in Basel in 2007. Although there is consensus about the definition and the diagnostic criteria of various forms of tooth wear, gaps in research strategies have been identified. A basic problem is that fundamental concepts of wear and erosion as an oral health problem, have not yet been sufficiently defined. To a certain extent, tooth wear is a physiological condition, and there is no consensus as to whether it can be regarded as a disease. Furthermore, the multitude of indices and flaws in existing indices, make published data difficult to interpret. Topics for the research agenda are: the initiation of a consensus process towards an internationally accepted index, and the initiation of data collection on the prevalence of various forms of wear on a population-based level. There should be an emphasis on promoting communication between basic and clinical sciences, and the area of Public Health Dentistry. Furthermore, the question of whether tooth wear is a public health problem remains open for debate.

Effect of denture cleaning on abrasion resistance and surface topography of polymerized CAD CAM acrylic resin denture base

PubMed Central

Shinawi, Lana Ahmed

2017-01-01

Background The application of computer-aided design computer-aided manufacturing (CAD CAM) technology in the fabrication of complete dentures, offers numerous advantages as it provides optimum fit and eliminates polymerization shrinkage of the acrylic base. Additionally, the porosity and surface roughness of CAD CAM resins is less compared to conventionally processed resins which leads to a decrease in the adhesion of bacteria on the denture base, which is associated with many conditions including halitosis and aspiration pneumonia in elderly denture wearers. Aim To evaluate the influence of tooth brushing with dentifrices on CAD CAM resin blocks in terms of abrasion resistance, surface roughness and scanning electron photomicrography. Methods This experimental study was carried out at the Faculty of Dentistry of King Abdulaziz University during 2016. A total of 40 rectangular shaped polymerized CAD CAM resin samples were subjected to 40.000 and 60.000 brushing strokes under a 200-gram vertical load simulating three years of tooth brushing strokes using commercially available denture cleaning dentifrice. Data were analyzed by SPSS version 20, using descriptive statistics and ANOVA. Results ANOVA test revealed a statistical significant weight loss of CAD CAM acrylic resin denture base specimens following 40.000 and 60.000 brushing strokes as well as a statistical significant change (p=0.0.5) in the surface roughness following brushing. The CAD CAM resin samples SEM baseline imaging revealed a relatively smooth homogenous surface, but following 40,000 and 60,000 brushing strokes, imaging displayed the presence of small scratches on the surface. Conclusion CAD CAM resin displayed a homogenous surface initially with low surface roughness that was significantly affected following simulating three years of manual brushing, but despite the significant weight loss, the findings are within the clinically acceptable limits. PMID:28713496

Effect of denture cleaning on abrasion resistance and surface topography of polymerized CAD CAM acrylic resin denture base.

PubMed

Shinawi, Lana Ahmed

2017-05-01

The application of computer-aided design computer-aided manufacturing (CAD CAM) technology in the fabrication of complete dentures, offers numerous advantages as it provides optimum fit and eliminates polymerization shrinkage of the acrylic base. Additionally, the porosity and surface roughness of CAD CAM resins is less compared to conventionally processed resins which leads to a decrease in the adhesion of bacteria on the denture base, which is associated with many conditions including halitosis and aspiration pneumonia in elderly denture wearers. To evaluate the influence of tooth brushing with dentifrices on CAD CAM resin blocks in terms of abrasion resistance, surface roughness and scanning electron photomicrography. This experimental study was carried out at the Faculty of Dentistry of King Abdulaziz University during 2016. A total of 40 rectangular shaped polymerized CAD CAM resin samples were subjected to 40.000 and 60.000 brushing strokes under a 200-gram vertical load simulating three years of tooth brushing strokes using commercially available denture cleaning dentifrice. Data were analyzed by SPSS version 20, using descriptive statistics and ANOVA. ANOVA test revealed a statistical significant weight loss of CAD CAM acrylic resin denture base specimens following 40.000 and 60.000 brushing strokes as well as a statistical significant change (p=0.0.5) in the surface roughness following brushing. The CAD CAM resin samples SEM baseline imaging revealed a relatively smooth homogenous surface, but following 40,000 and 60,000 brushing strokes, imaging displayed the presence of small scratches on the surface. CAD CAM resin displayed a homogenous surface initially with low surface roughness that was significantly affected following simulating three years of manual brushing, but despite the significant weight loss, the findings are within the clinically acceptable limits.

Improved performance of selective ablation using a specially designed handpiece

NASA Astrophysics Data System (ADS)

Hennig, Thomas; Rechmann, Peter

1996-01-01

Selective ablation is fixed to a range of fluences predicted by the ablation thresholds of infected and healthy tooth structures respectively. The aim of the study was to develop a dental handpiece, which guarantees homogeneous fluence at the irradiated tooth surface. Furthermore the point of treatment should be cooled down without energy losses due to the cooling system. We suggest the direct coupling of the laser radiation into a laminar stream of liquid, which may act in turn as a lengthened beam guide. The impacts of the laser radiation and of the cooling medium hit exactly the same point. Hot ablation debris is removed out of the crater by the flush of the water jet. While the surface of a bare fiber working on contact mode is destroyed after a few shots, it was shown that coupling the laser radiation into a stream of liquid prevents this destruction. Putting together the benefits of this special handpiece short overall treatment times seem to be possible. High average power can be applied to the tooth without the threat of thermal damage. Furthermore no time consuming cutting of the fiber prolongs the treatment time.

Microprocessing of human hard tooth tissues surface by mid-infrared erbium lasers radiation

NASA Astrophysics Data System (ADS)

Belikov, Andrey V.; Shatilova, Ksenia V.; Skrypnik, Alexei V.

2015-03-01

A new method of hard tooth tissues laser treatment is described. The method consists in formation of regular microdefects on tissue surface by mid-infrared erbium laser radiation with propagation ratio M2<2 (Er-laser microprocessing). Proposed method was used for preparation of hard tooth tissues surface before filling for improvement of bond strength between tissues surface and restorative materials, microleakage reduction between tissues surface and restorative materials, and for caries prevention as a result of increasing microhardness and acid resistance of tooth enamel.

Building osteoporosis prevention into dental practice.

PubMed

Stewart, Stacey; Hanning, Rhona

2012-01-01

The National Report Card on Osteoporosis Care (2008) announced the need for comprehensive approaches to risk reduction and improvement in the early diagnosis of osteoporosis. Dental research has suggested that low systemic bone-mineral density also occurs in alveolar bone, and people with osteoporosis may have an increased risk of tooth loss. Whether or not a causal link exists, both conditions share similar modifiable risk factors, including a role for calcium and vitamin D. The purpose of this paper was to critically examine the role calcium and vitamin D play in the relationship between osteoporosis and the risk of tooth loss. Scientific articles were obtained through PubMed, MEDLINE, CINAHL, AgeLine and Web of Science. Publications were restricted to those involving human subjects, and English-language articles on calcium and vitamin D. The search yielded 8 articles relating to osteoporosis and tooth loss that included calcium and vitamin D intake. Despite methodological concerns, the evidence shows a relationship between osteoporosis and tooth loss for people who have an inadequate intake of calcium and vitamin D. Adequate calcium intake positively influences optimal peak bone mass and may also assist in tooth retention in later life. The dental sector can assist with national prevention strategies for osteoporosis care.

Tooth-meshing-harmonic static-transmission-error amplitudes of helical gears

NASA Astrophysics Data System (ADS)

Mark, William D.

2018-01-01

The static transmission errors of meshing gear pairs arise from deviations of loaded tooth working surfaces from equispaced perfect involute surfaces. Such deviations consist of tooth-pair elastic deformations and geometric deviations (modifications) of tooth working surfaces. To a very good approximation, the static-transmission-error tooth-meshing-harmonic amplitudes of helical gears are herein expressed by superposition of Fourier transforms of the quantities: (1) the combination of tooth-pair elastic deformations and geometric tooth-pair modifications and (2) fractional mesh-stiffness fluctuations, each quantity (1) and (2) expressed as a function of involute "roll distance." Normalization of the total roll-distance single-tooth contact span to unity allows tooth-meshing-harmonic amplitudes to be computed for different shapes of the above-described quantities (1) and (2). Tooth-meshing harmonics p = 1, 2, … are shown to occur at Fourier-transform harmonic values of Qp, p = 1, 2, …, where Q is the actual (total) contact ratio, thereby verifying its importance in minimizing transmission-error tooth-meshing-harmonic amplitudes. Two individual shapes and two series of shapes of the quantities (1) and (2) are chosen to illustrate a wide variety of shapes. In most cases representative of helical gears, tooth-meshing-harmonic values p = 1, 2, … are shown to occur in Fourier-transform harmonic regions governed by discontinuities arising from tooth-pair-contact initiation and termination, thereby showing the importance of minimizing such discontinuities. Plots and analytical expressions for all such Fourier transforms are presented, thereby illustrating the effects of various types of tooth-working-surface modifications and tooth-pair stiffnesses on transmission-error generation.

Wear of two pit and fissure sealants in contact with primary teeth

PubMed Central

Galo, Rodrigo; Contente, Marta Maria Martins Giamatei; Borsatto, Maria Cristina

2014-01-01

Objectives: Wear simulations may provide an indication of the clinical performance of pit-and-fissure sealants when associated with primary teeth as counterbody, restricting the involved variables. The aim of this study was to evaluate wear of dental materials used as pit-and-fissure sealants in contact with primary teeth. Materials and Methods: A resinous sealant (Fluroshield®) and a resin-modified glass ionomer cement (Vitremer®) were selected in a post-plate design, using as counterbody primary tooth pins (4 × 4 × 2 mm) at 3 and 10 N vertical load, 1 Hz frequency, 900 wear cycles in artificial saliva (n = 15). Attrition coefficient values were obtained and the material and primary tooth volumes were analyzed. Data were analyzed statistically by ANOVA and Duncan's test (P < 0.05). Results: Fluroshield® presented the highest attrition coefficient values for the 3 N but these values decreased significantly for the 10 N load. The means for volume loss (3 mm) of the different samples after the wear test were not statistically different for the materials. The volume loss values for the primary teeth were statistically different and there was an increase in volume loss with the increase of the load applied in the wear tests. Conclusions: Differences were also observed with regard to the surface deformation characteristics. The wear rates of primary tooth enamel vary according to the type of material and the load applied during mastication. PMID:24966777

The Importance of Tooth Decay Prevention in Children under Three

ERIC Educational Resources Information Center

Milgrom, Peter; Huebner, Colleen; Chi, Donald

2010-01-01

Tooth decay and tooth loss was once the norm but public health interventions have led to major improvements for most people. Nevertheless, not all children have benefited. Dental disease in young children is unacceptably high. Tooth decay is preventable. Early childhood educators are often the first to notice the problem. Professional…

Longitudinal changes in tooth/single-implant relationship and bone topography: an 8-year retrospective analysis.

PubMed

Chang, Moontaek; Wennström, Jan L

2012-06-01

To evaluate longitudinal changes in tooth/implant relationship and bone topography at single implants with a microthreaded, conical marginal portion (Astra Tech ST® implants, Astra Tech AB, Mölndal, Sweden). Thirty-one subjects with single implant-supported restorations in the esthetic zone were included. Radiographs obtained at crown installation and 1, 5, and 8 years of follow-up were analyzed with regard to changes in (1) bone level at the implant and adjacent teeth and (2) vertical position of adjacent teeth relative to the single implant. The mean marginal bone loss amounted to 0.1 mm at both implants and adjacent teeth during the 8 years of follow-up. Regression analysis failed to identify significant explanatory factors for observed variance in bone level change at the adjacent tooth surfaces. Vertical change in position of the teeth relative to the implants was more frequent and significantly greater in incisor compared with premolar tooth region but not associated with gender or age. The marginal bone level at teeth adjacent to single implants with a microthreaded conical marginal part was not influenced by horizontal and vertical tooth-implant distances. Continuous eruption of adjacent teeth may result in infraocclusal positioning of a single-implant restoration. © 2010 Wiley Periodicals, Inc.

Do pediatric medicines induce topographic changes in dental enamel?

PubMed

Alexandria, Adílis Kalina; Meckelburg, Nicolli de Araujo; Puetter, Ursula Tavares; Salles, Jordan Trugilho; Souza, Ivete Pomarico Ribeiro; Maia, Lucianne Cople

2016-01-01

The purpose of the present study was to evaluate the effect of common pediatric liquid medicines on surface roughness and tooth structure loss and to evaluate the pH values of these medicines at room and cold temperatures in vitro. Eighty-four bovine enamel blocks were divided into seven groups (n = 12): G1-Alivium®, G2-Novalgina®, G3-Betamox®, G4-Clavulin®, G5-Claritin®, G6-Polaramine® and G7-Milli-Q water (negative control). The pH was determined and the samples were immersed in each treatment 3x/day for 5 min. 3D non-contact profilometry was used to determine surface roughness (linear Ra, volumetric Sa) and the Gap formed between treated and control areas in each block. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were also performed. The majority of liquid medicines had pH ≤ 5.50. G1, G4, and G5 showed alterations in Ra when compared with G7 (p < 0.05). According to Sa and Gap results, only G5 was different from G7 (p < 0.05). Alteration in surface was more evident in G5 SEM images. EDS revealed high concentrations of carbon, oxygen, phosphorus, and calcium in all tested groups. Despite the low pH values of all evaluated medicines, only Alivium®, Clavulin®, and Claritin® increased linear surface roughness, and only Claritin® demonstrated the in vitro capacity to produce significant tooth structure loss.

Computer-aided design of bevel gear tooth surfaces

NASA Technical Reports Server (NTRS)

Shuo, Hung Chang; Huston, Ronald L.; Coy, John J.

1989-01-01

This paper presents a computer-aided design procedure for generating bevel gears. The development is based on examining a perfectly plastic, cone-shaped gear blank rolling over a cutting tooth on a plane crown rack. The resulting impression on the plastic gear blank is the envelope of the cutting tooth. This impression and envelope thus form a conjugate tooth surface. Equations are presented for the locus of points on the tooth surface. The same procedures are then extended to simulate the generation of a spiral bevel gear. The corresponding governing equations are presented.

Computer aided design of bevel gear tooth surfaces

NASA Technical Reports Server (NTRS)

Chang, S. H.; Huston, R. L.; Coy, J. J.

1989-01-01

This paper presents a computer-aided design procedure for generating bevel gears. The development is based on examining a perfectly plastic, cone-shaped gear blank rolling over a cutting tooth on a plane crown rack. The resulting impression on the plastic gear blank is the envelope of the cutting tooth. This impression and envelope thus form a conjugate tooth surface. Equations are presented for the locus of points on the tooth surface. The same procedures are then extended to simulate the generation of a spiral bevel gear. The corresponding governing equations are presented.

In vitro reproduction of incisal/occlusal cupping/cratering.

PubMed

Dzakovich, John J; Oslak, Robert R

2013-06-01

Occlusal cupping/cratering (depressed dentin surrounded by elevated rims of enamel) has been postulated to be the result of abrasion, bruxism, attrition, acid erosion, stress corrosion, or a combination of these. The primary etiology or the multifactorial sequence of occlusal cupping/cratering remains scientifically unsubstantiated. The purpose of this study was to reproduce occlusal/incisal cupping/cratering in vitro. This study was designed to create cupping/cratering on the occlusal surfaces of extracted human teeth rather than to quantify the amount of lost tooth structure caused by abrasion. One name-brand toothbrush was tested with 2 different dentifrices (of different abrasive potentials [low and high]) and water only (nonabrasive) on extracted human teeth. Six specimens of 4 teeth each (24 teeth) were subjected to horizontal brushing in a 1:1 toothpaste/water slurry and water only. The control group, brushed with water only, demonstrated no visible loss of tooth structure. Each of the specimens brushed with toothpaste, regardless of the degree of abrasivity, demonstrated visible wear of the dentin, resulting in occlusal/incisal cupping/cratering. Pronounced cupping/cratering was caused by horizontal brushing with commercial toothpastes. Brushing in water demonstrated no visual loss of occlusal tooth structure. (J Prosthet Dent 2013;109:384-391). Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Human Histologic Repair and Regeneration After Biologic Preparation of Diseased Root Surfaces,

DTIC Science & Technology

1983-12-01

Continue on reverse side if neceesar and Identify by block number) Periodontal disease Tooth roots Connective tissue regeneration 20 ABSTRACT (Continue on... regeneration of periodontal attachment loss, due to inflammatory periodontal disease (1). Most procedures for new attachment achieve a new dentogingival...good appearance for a lifetime. Oral hygiene is the most important factor in the prevention and treatment of inflammatory periodontal diseases

Automated ablation of dental composite using an IR pulsed laser coupled to a plume emission spectral feedback system.

PubMed

Jang, Andrew T; Chan, Kenneth H; Fried, Daniel

2017-09-01

The purpose of this study is to assemble a laser system for the selective removal of dental composite from tooth surfaces, that is feasible for clinical use incorporating a spectral feedback system, a scanning system, articulating arm and a clinical hand-piece, and evaluate the performance of that system on extracted teeth. Ten extracted teeth were collected and small fillings were placed on the occlusal surface of each tooth. A clinical system featuring a CO 2 laser operating at 50 Hz and spectral optical feedback was used to remove the composite. Removal was confirmed using a cross polarized optical coherence tomography (CP-OCT) system designed for clinical use. The system was capable of rapidly removing composite from small preparations on tooth occlusal surfaces with a mean loss of enamel of less than 20 μm. We have demonstrated that spectral feedback can be successfully employed in an automated system for composite removal by incorporating dual photodiodes and a galvanometer controlled CO 2 laser. Additionally, the use of registered OCT images presents as a viable method for volumetric benchmarking. Overall, this study represents the first implementation of spectral feedback into a clinical hand-piece and serves as a benchmark for a future clinical study. Lasers Surg. Med. 49:658-665, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Are Lowered Socioeconomic Circumstances Causally Related to Tooth Loss? A Natural Experiment Involving the 2011 Great East Japan Earthquake.

PubMed

Matsuyama, Yusuke; Aida, Jun; Tsuboya, Toru; Hikichi, Hiroyuki; Kondo, Katsunori; Kawachi, Ichiro; Osaka, Ken

2017-07-01

Oral health status is correlated with socioeconomic status. However, the causal nature of the relationship is not established. Here we describe a natural experiment involving deteriorating socioeconomic circumstances following exposure to the 2011 Great East Japan Earthquake and Tsunami. We investigated the relationship between subjective economic deterioration and housing damage due to the disaster and tooth loss in a cohort of community-dwelling residents (n = 3,039), from whom we obtained information about socioeconomic status and health status in 2010 (i.e., predating the disaster). A follow-up survey was performed in 2013 (postdisaster), and 82.1% of the 4,380 eligible survivors responded. We estimated the impact of subjective economic deterioration and housing damage due to the disaster on tooth loss by fitting an instrumental variable probit model. Subjective economic deterioration and housing damage due to the disaster were significantly associated with 8.1% and 1.7% increases in the probability of tooth loss (probit coefficients were 0.469 (95% confidence interval: 0.065, 0.872) and 0.103 (95% confidence interval: 0.011, 0.196), respectively). In this natural experiment, we confirmed the causal relationship between deteriorating socioeconomic circumstances and tooth loss. © The Author 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Diet-borne systemic inflammation is associated with prevalent tooth loss.

PubMed

Kotsakis, Georgios A; Chrepa, Vanessa; Shivappa, Nitin; Wirth, Michael; Hébert, James; Koyanagi, Ai; Tyrovolas, Stefanos

2017-06-09

The deleterious effect of cariogenic dietary patterns on tooth loss is well characterized, but the contribution of diet-borne systemic inflammation to loss of teeth remains uncharted. Recent efforts have unveiled a protective role of single nutrients to periodontal health. However, the assessment of overall diet as a modifiable risk factor for oral health remains elusive. Thus, the aim of this study was to assess the association between diet-borne systemic inflammation and tooth loss in a representative sample of the US adult non-institutionalized population. A cross-sectional analysis of a sample of participants of the 2009-2010 and 2011-2012 continuous NHANES receiving an oral exam and providing dietary recall data was performed. Dietary inflammatory potential was assessed by the Dietary Inflammatory Index (DII), a composite measure computed based on the association between nutrients and systemic pro-inflammatory cytokine levels. The outcome measure was prevalent tooth loss. Numbers of missing teeth were regressed across quartiles of the DII using multivariable linear regression models. 6887 eligible NHANES participants were included in the analysis; participants in the highest quartile of the DII index (pro-inflammatory diet) had an average [95% CI] of 0.84 [0.24, 1.45] additional more teeth lost as compared to those in the lowest quartile of DII (anti-inflammatory diet) (p = 0.015), after adjusting for known confounders. This significant association remained in subgroup analyses, including the lowest tertiles of energy-adjusted carbohydrate intake, and in persons aged ≥50 years. Adherence to an anti-inflammatory diet is associated with fewer missing teeth. These results suggest protective dietary patterns as a modifiable protective factor for tooth loss in the US adult population and support the incorporation of tooth loss prevention in the agenda of dietary public health interventions to prevent chronic inflammatory diseases. Copyright © 2017 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Marginal Bone Loss after Ten Years in an Adult Danish Population: A Radiographic Study.

PubMed

Bahrami, Golnosh; Vaeth, Michael; Wenzel, Ann; Isidor, Flemming

To evaluate marginal bone loss over a 10-year period in individuals and in tooth groups in relation to age and level of marginal bone. In 1997, 616 randomly selected individuals (mean age: 42 years, range: 21-63 years) underwent a full-mouth radiographic survey. In 2008, the survey was repeated in 362 of the same individuals (182 women and 180 men). The marginal bone level of each tooth was measured in mm from the cementoenamel junction to the marginal bone. These measurements were used to calculate marginal bone loss during the 10-year period for individuals and tooth groups in relation to age and to baseline marginal bone level, calculated as the average between measurements in 1997 and 2008 to circumvent regression towards the mean. The average annual marginal bone loss was 0.09 mm (SD ± 0.04 mm) during the 10-year study period. The association between marginal bone loss and baseline marginal bone level was more pronounced in the youngest age group, compared to the other age groups. Molars displayed the most severe bone loss during the study period. Marginal bone loss over a 10-year period is associated with age and baseline marginal bone level. Younger individuals with a reduced marginal bone level were at higher risk for further bone loss. Molars lose marginal bone more rapidly than other tooth groups.

The prevalence, aetiology and clinical appearance of tooth wear: the Nigerian experience.

PubMed

Oginni, O; Olusile, A O

2002-08-01

To establish the prevalence and severity of tooth wear among Nigerians and to compare the pattern and aetiology with findings of earlier studies in Western populations. Clinical examinations for tooth wear using the tooth wear index (TWI). The Federal Republic of Nigeria. Patients attending the Dental Hospital, Obafemi Awolowo University Teaching Hospital's Complex Ile-Ife. Attrition, abrasion and erosion. Of the 126 patients with tooth wear 81 had attrition, 20 had abrasion, 9 had erosion and 16 had attrition and abrasion combined. A total of 15,480 tooth surfaces were examined. 2,229 (14.4%) surfaces had tooth wear out of which 1,007 (6.5%) were pathologically worn down. The frequency of tooth wear increased with the age of patients. Most of the pathologically worn surfaces were just one point above maximum acceptable value. The aetiological factors associated with tooth wear are not different from those encountered in Western cultures but the pattern of wear differs. Pathological tooth wear presents as an age related phenomenon and is probably more severe in Nigerians.

Acquired pellicle as a modulator for dental erosion.

PubMed

Vukosavljevic, Dusa; Custodio, William; Buzalaf, Marilia A R; Hara, Anderson T; Siqueira, Walter L

2014-06-01

Dental erosion is a multifactorial condition that can result in the loss of tooth structure and function, potentially increasing tooth sensitivity. The exposure of enamel to acids from non-bacterial sources is responsible for the progression of erosion. These erosive challenges are counteracted by the anti-erosive properties of the acquired pellicle (AP), an integument formed in vivo as a result of selective adsorption of salivary proteins on the tooth surface, containing also lipids and glycoproteins. This review provides an in-depth discussion regarding how the physical structure of the AP, along with its composition, contributes to AP anti-erosive properties. The physical properties that contribute to AP protective nature include pellicle thickness, maturation time, and site of development. The pellicle contains salivary proteins embedded within its structure that demonstrate anti-erosive properties; however, rather than individual proteins, protein-protein interactions play a fundamental role in the protective nature of the AP. In addition, dietary and synthetic proteins can modify the pellicle, enhancing its protective efficiency against dental erosion. The salivary composition of the AP and its corresponding protein-profile may be employed as a diagnostic tool, since it likely contains salivary biomarkers for oral diseases that initiate at the enamel surface, including dental erosion. Finally, by modifying the composition and structure of the AP, this protein integument has the potential to be used as a target-specific treatment option for oral diseases related to tooth demineralization. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effect of a static magnetic field on orthodontic tooth movement in the rat.

PubMed

Tengku, B S; Joseph, B K; Harbrow, D; Taverne, A A; Symons, A L

2000-10-01

Orthodontic tooth movement may be enhanced by the application of a magnetic field. Bone remodelling necessary for orthodontic tooth movement involves clastic cells, which are tartrate-resistant acid phosphatase (TRAP) positive and which may also be regulated by growth hormone (GH) via its receptor (GHR). The aim of this study was to determine the effect of a static magnetic field (SMF) on orthodontic tooth movement in the rat. Thirty-two male Wistar rats, 9 weeks old, were fitted with an orthodontic appliance directing a mesial force of 30 g on the left maxillary first molar. The appliance incorporated a weight (NM) or a magnet (M). The animals were killed at 1, 3, 7, or 14 days post-appliance insertion, and the maxillae processed to paraffin. Sagittal sections of the first molar were stained with haematoxylin and eosin (H&E), for TRAP activity or immunohistochemically for GHR. The percentage body weight loss/gain, magnetic flux density, tooth movement, width of the periodontal ligament (PDL), length of root resorption lacunae, and hyalinized zone were measured. TRAP and GHR-positive cells along the alveolar bone, root surface, and in the PDL space were counted. The incorporation of a SMF (100-170 Gauss) into an orthodontic appliance did not enhance tooth movement, nor greatly alter the histological appearance of the PDL during tooth movement. However significantly greater root resorption (P = 0.016), increased width of the PDL (P = 0.017) and greater TRAP activity (P = 0.001) were observed for group M at day 7 on the compression side. At day 14 no differences were observed between the appliance groups.

Mathematical models for the synthesis and optimization of spiral bevel gear tooth surfaces. [for helicopter transmissions

NASA Technical Reports Server (NTRS)

Litvin, F. L.; Rahman, P.; Goldrich, R. N.

1982-01-01

The geometry of spiral bevel gears and to their rational design are studied. The nonconjugate tooth surfaces of spiral bevel gears are, in theory, replaced (or approximated) by conjugated tooth surfaces. These surfaces can be generated by two conical surfaces, and by a conical surface and a revolution. Although these conjugated tooth surfaces are simpler than the actual ones, the determination of their principal curvatures and directions is still a complicated problem. Therefore, a new approach, to the solution of these is proposed. Direct relationships between the principal curvatures and directions of the tool surface and those of the generated gear surface are obtained. With the aid of these analytical tools, the Hertzian contact problem for conjugate tooth surfaces can be solved. These results are useful in determining compressive load capacity and surface fatigue life of spiral bevel gears. A general theory of kinematical errors exerted by manufacturing and assembly errors is developed. This theory is used to determine the analytical relationship between gear misalignments and kinematical errors. This is important to the study of noise and vibration in geared systems.

Mechanical modelling of tooth wear

PubMed Central

Kallonen, Aki

2016-01-01

Different diets wear teeth in different ways and generate distinguishable wear and microwear patterns that have long been the basis of palaeodiet reconstructions. Little experimental research has been performed to study them together. Here, we show that an artificial mechanical masticator, a chewing machine, occluding real horse teeth in continuous simulated chewing (of 100 000 chewing cycles) is capable of replicating microscopic wear features and gross wear on teeth that resemble wear in specimens collected from nature. Simulating pure attrition (chewing without food) and four plant material diets of different abrasives content (at n = 5 tooth pairs per group), we detected differences in microscopic wear features by stereomicroscopy of the chewing surface in the number and quality of pits and scratches that were not always as expected. Using computed tomography scanning in one tooth per diet, absolute wear was quantified as the mean height change after the simulated chewing. Absolute wear increased with diet abrasiveness, originating from phytoliths and grit. In combination, our findings highlight that differences in actual dental tissue loss can occur at similar microwear patterns, cautioning against a direct transformation of microwear results into predictions about diet or tooth wear rate. PMID:27411727

Ultrasonic device for measuring periodontal attachment levels

NASA Astrophysics Data System (ADS)

Lynch, J. E.; Hinders, M. K.

2002-07-01

Periodontal disease is manifested clinically by a degradation of the ligament that attaches the tooth to the bone. The most widely used diagnostic tool for assessment of periodontal diseases, measurement of periodontal attachment loss with a manual probe, may overestimate attachment loss by as much as 2 mm in untreated sites, while underestimating attachment loss by an even greater margin following treatment. Manual probing is also invasive, which causes patient discomfort. This work describes the development and testing of an ultrasonographic periodontal probe designed to replace manual probing. It uses a thin stream of water to project an ultrasonic beam into the periodontal pocket, and then measures echoes off features within the pocket. To do so, the ultrasonic beam must be narrowed from 2 (the diameter of the transducer) to 0.5 mm (the approximate width of the periodontal pocket at the gingival margin). The proper choice of transducer frequency, the proper method for controlling water flow from the probe, and a model for interpreting these echoes are also addressed. Initial results indicate that the device measures echoes from the hard tissue of the tooth surface, and that the periodontal attachment level can be inferred from these echoes.

Natural Tooth Pontic: An Instant Esthetic Option for Periodontally Compromised Teeth—A Case Series

PubMed Central

Raj, Rishi; Narayan, Ipshita; Gowda, Triveni Mavinakote; Mehta, D. S.

2016-01-01

Sudden tooth loss in the esthetic zone of the maxillary or mandibular anterior region can be due to trauma, periodontal disease, or endodontic failure. The treatment options for replacing the missing tooth can vary between removable prosthesis, tooth-supported prosthesis, and implant-supported prosthesis. Irrespective of the final treatment, the first line of management would be to provisionally restore the patient's esthetic appearance at the earliest, while functionally stabilizing the compromised arch. Using the patient's own natural tooth as a pontic offers the benefits of being the right size, shape, and color and provides exact repositioning in its original intraoral three-dimensional position. Additionally, using the patient's platelet concentrate (platelet rich fibrin) facilitates early wound healing and preservation of alveolar ridge shape following tooth extraction. The abutment teeth can also be preserved with minimal or no preparation, thus keeping the technique reversible, and can be completed at the chair side thereby avoiding laboratory costs. This helps the patient better tolerate the effect of tooth loss psychologically. The article describes a successful, immediate, and viable technique for rehabilitation of three different patients requiring replacement of a single periodontally compromised tooth in an esthetic region. PMID:27994892

Interactive effects of periodontitis and orthodontic tooth movement on dental root resorption, tooth movement velocity and alveolar bone loss in a rat model.

PubMed

Kirschneck, Christian; Fanghänel, Jochen; Wahlmann, Ulrich; Wolf, Michael; Roldán, J Camilo; Proff, Peter

2017-03-01

Many adult orthodontic patients suffer from chronic periodontitis with recurrent episodes of active periodontal inflammation. As their number is steadily increasing, orthodontists are more and more frequently challenged by respective treatment considerations. However, little is currently known regarding interactive effects on undesired dental root resorption (DRR), tooth movement velocity, periodontal bone loss and the underlying cellular and tissue reactions. A total of 63 male Fischer344 rats were used in three consecutive experiments employing 21 animals each (A/B/C), randomly assigned to 3 experimental groups (n=7, 1/2/3), respectively: (A) CBCT; (B) histology/serology; (C) RT-qPCR-(1) control; (2) orthodontic tooth movement (OTM) of the first/second upper left molars (NiTi coil spring, 0.25N); (3) OTM with experimentally induced periodontitis (cervical silk ligature). After 14days of OTM, we quantified blood leukocyte level, DRR, osteoclast activity and relative gene expression of inflammatory and osteoclast marker genes within the dental-periodontal tissue as well as tooth movement velocity and periodontal bone loss after 14 and 28 days. The experimentally induced periodontal bone loss was significantly increased by concurrent orthodontic force application. Periodontal inflammation during OTM on the other hand significantly augmented the extent of DRR, relative expression of inflammatory/osteoclast marker genes, blood leukocyte level and periodontal osteoclast activity. In addition, contrary to previous studies, we observed a significant increase in tooth movement velocity. Although accelerated tooth movement would be favourable for orthodontic treatment, our results suggest that orthodontic interventions should only be performed after successful systematic periodontal therapy and paused in case of recurrent active inflammation. Copyright © 2016 Elsevier GmbH. All rights reserved.

Temporary employment and tooth loss: a cross-sectional study from the J-SHINE study.

PubMed

Sato, Yukihiro; Tsuboya, Toru; Watt, Richard G; Aida, Jun; Osaka, Ken

2018-02-21

Temporary employment leads to psychological distress and higher mortality, but data on its associations with oral health is limited. We examined whether having the experience of temporary employment was associated with tooth loss among working adults in Japan. We conducted a cross-sectional study from the 2010-2011 Japanese Study on Stratification, Health, Income, and Neighborhood study that analyzed 2652 participants aged 25-50 years (men = 1394; women = 1258). Independent variable was changes in employment status (continuous regular employment and the experience of temporary employment). Dependent variable was self-reported tooth loss (none, 1 tooth, 2 teeth, 3 teeth, 4 teeth, and more than 4 teeth). Covariates were sex, age, years of education, self-rated household economic status in early life at 5 years old, marital status, number of family members in the household, history of diabetes, and body mass index. We conducted a negative binomial regression analysis to estimate prevalence rate ratios (PRRs) and 95% confidence intervals (95%CIs) for tooth loss. We also confirmed the interaction term between changes in employment status and sex. The median age of the participants was 37 years. The percentages of men and women who experienced temporary employment were 14.5% and 61.3%, respectively. Compared with continuous regular employment, the experience of temporary employment was significantly associated with tooth loss in both sexes after adjusting for the covariates (men: PRR = 1.50 [95%CI = 1.13, 2.00]; women: PRR = 1.42 [95%CI = 1.14, 1.76]). The interaction term between employment status and sex was not significant (p = 0.71). Temporary employment is adversely associated with oral health.

Association between type 1 and type 2 diabetes with periodontal disease and tooth loss.

PubMed

Kaur, Gaganpreet; Holtfreter, Birte; Rathmann, Wolfgang; Rathmann, Wolfgan G; Schwahn, Christian; Wallaschofski, Henry; Schipf, Sabine; Nauck, Matthias; Kocher, Thomas

2009-09-01

The aim of this study was to determine whether both type 1 (T1DM) and type 2 diabetes mellitus (T2DM) are associated with increased prevalence and extent of periodontal disease and tooth loss compared with non-diabetic subjects within a homogeneous adult study population. T1DM, T2DM and non-diabetic subjects were recruited from the population-based Study of Health in Pomerania. Additionally, T1DM subjects were retrieved from a Diabetes Centre. The total study population comprised 145 T1DM and 2647 non-diabetic subjects aged 20-59 years, and 182 T2DM and 1314 non-diabetic subjects aged 50-81 years. Periodontal disease was assessed by attachment loss (AL) and the number of missing teeth. Multivariable regression revealed an association between T1DM (p<0.001) and T2DM (p<0.01) with mean AL after full adjustment. After age stratification (p=0.04 for interaction), the effect of T2DM was only statistically significant in the 60-69-year-old subjects (B=0.90 (95% confidence intervals [95% CI]; 0.49, 1.31). T1DM was positively associated with tooth loss (adjusted, p<0.001). The association between T2DM and tooth loss was statistically significant only for females (odds ratios=1.60 [95% CI: 1.10, 2.33]). Our study confirmed an association between both T1DM and T2DM with periodontitis and tooth loss. Therefore, oral health education should be promoted in diabetic subjects.

The erosive effect of herbal tea on dental enamel.

PubMed

Brunton, P A; Hussain, A

2001-11-01

The aim of this study was to determine whether conventional black tea and a herbal tea were capable of eroding dental enamel. A further aim was to investigate whether herbal tea of the type tested eroded dental hard tissues to a greater or lesser extent than conventional black tea. Three groups of 21 teeth were exposed to a conventional black tea Typhoo (Group A), a herbal tea Twinings Blackcurrant, Ginsing and Vanilla (Group B) and water, which acted as a control (Group C). Sequential profilometric tracings of the specimens were taken, superimposed and the degree of enamel loss calculated as the area of disparity between the tracings before and after exposure. Conventional black tea and herbal tea, of the type tested, both resulted in tooth surface loss. Tooth surface loss, which resulted from exposure to herbal tea (mean 0.05mm(2), s.d. 0.02), however, was significantly greater (P=0.00) than that which resulted from exposure to conventional black tea (mean 0.01mm(2), s.d. 0.00) and water (mean 0.00mm(2), s.d. 0.00). It was concluded that herbal tea and conventional black tea of the type tested result in erosion of dental enamel. The erosive effect of the herbal tea of the type tested was five times more severe than that of the conventional black tea tested. The cumulative effects of regular consumption of herbal tea of the type tested are likely, therefore, to be of clinical significance.

Scanning electron microscopic and X-ray micro analysis on tooth enamel exposed to alkaline agents.

PubMed

Taubee, Fabian; Steiniger, Frank; Nietzsche, Sandor; Norén, Jörgen G

2010-01-01

The background of this study comprises two clinical cases, where patients exposed to aerosols of an alkaline and surface active cleaning agent developed loss of enamel substance on their teeth, further resulting in loss of teeth and partially destroyed soft tissues. The alkaline cleaning agent consisted of potassium hydroxide and various surfactants. The purpose of this study was to investigate possible changes in morphology and composition in human teeth enamel exposed to alkaline solutions, by means of X-ray micro analysis (XRMA), FTIR-spectroscopic analyses and scanning electron microscopy (SEM). Extracted premolars, exposed to potassium hydroxide solutions and alkaline cleaning solution,were analyzed by means of XRMA and SEM. Enamel powder, exposed to cleaning solution, was analyzed by means of FTIR. The SEM analysis revealed an increased porosity of the enamel surface and partially loss of enamel substance after exposure to alkaline solutions. The XRMA analyses revealed a decrease in carbon concentration while phosphorous and calcium showed no marked changes. The FTIR analyses showed no significant changes in peak heights or peak positions for phosphate, carbonate or hydroxide. It was concluded that human teeth enamel exposed to alkaline solutions showed loss of organic substance, marked pores in enamel surface and loss of substance in the enamel surface.

Development and growth of compound tooth plates in Callorhinchus milii (chondrichthyes, holocephali).

PubMed

Didier, D A; Stahl, B J; Zangerl, R

1994-10-01

The chimaeroid holocephalian fishes are distinguished among extant chondrichthyans by the possession of three pairs of tooth plates, evergrowing and partially hypermineralized, that are not shed and replaced like the teeth of living elasmobranchs. Although derivation of the chimaeroid tooth plate from the fusion of members of a plesiomorphic chondrichthyan tooth family has been proposed, evidence for this hypothesis has been lacking. A new analysis of the development and structure of the tooth plates in Callorhinchus milii (Holocephali, Chimaeriformes) reveals the compound nature of the tooth plates in a chimaeroid fish. Each tooth plate consists of an oral and aboral territory that form independently in the embryo and maintain separate growth surfaces through life. The descending lamina on the aboral surface of the tooth plate demarcates the growth surface of the aboral territory. Comparison with the tooth plates of Chimaera monstrosa indicates that compound tooth plates may be a feature of all chimaeroids in which a descending lamina is present. The tooth plates in these fishes represent the fusion of two members of a reduced tooth family. The condition of the tooth plates in C. milii is plesiomorphic for chimaeroids and is of evolutionary significance in that it provides further evidence to support a lyodont dentition in chimaeroid fishes similar to that found in other chondrichthyans. © 1994 Wiley-Liss, Inc. Copyright © 1994 Wiley-Liss, Inc.

Visual and digital comparative tooth colour assessment methods and atomic force microscopy surface roughness.

PubMed

Grundlingh, A A; Grossman, E S; Shrivastava, S; Witcomb, M J

2013-10-01

This study compared digital and visual colour tooth colour assessment methods in a sample of 99 teeth consisting of incisors, canines and pre-molars. The teeth were equally divided between Control, Ozicure Oxygen Activator bleach and Opalescence Quick bleach and subjected to three treatments. Colour readings were recorded at nine intervals by two assessment methods, VITA Easyshade and VITAPAN 3D MASTER TOOTH GUIDE, giving a total of 1782 colour readings. Descriptive and statistical analysis was undertaken using a GLM test for Analysis of Variance for a Fractional Design set at a significance of P < 0.05. Atomic force micros copy was used to examine treated ename surfaces and establish surface roughness. Visual tooth colour assessment showed significance for the independent variables of treatment, number of treatments, tooth type and the combination tooth type and treatment. Digital colour assessment indicated treatment and tooth type to be of significance in tooth colour change. Poor agreement was found between visual and digital colour assessment methods for Control and Ozicure Oxygen Activator treatments. Surface roughness values increased two-fold for Opalescence Quick specimens over the two other treatments, implying that increased light scattering improved digital colour reading. Both digital and visual colour matching methods should be used in tooth bleaching studies to complement each other and to compensate for deficiencies.

Managing dental erosion.

PubMed

Curtis, Donald A; Jayanetti, Jay; Chu, Raymond; Staninec, Michal

2012-01-01

The clinical signs of dental erosion are initially subtle, yet often progress because the patient remains asymptomatic, unaware and uninformed. Erosion typically works synergistically with abrasion and attrition to cause loss of tooth structure, making diagnosis and management complex. The purpose of this article is to outline clinical examples of patients with dental erosion that highlight the strategy of early identification, patient education and conservative restorative management. Dental erosion is defined as the pathologic chronic loss of dental hard tissues as a result of the chemical influence of exogenous or endogenous acids without bacterial involvement. Like caries or periodontal disease, erosion has a multifactorial etiology and requires a thorough history and examination for diagnosis. It also requires patient understanding and compliance for improved outcomes. Erosion can affect the loss of tooth structure in isolation of other cofactors, but most often works in synergy with abrasion and attrition in the loss of tooth structure (Table 1). Although erosion is thought to be an underlying etiology of dentin sensitivity, erosion and loss of tooth structure often occurs with few symptoms. The purpose of this article is threefold: first, to outline existing barriers that may limit early management of dental erosion. Second, to review the clinical assessment required to establish a diagnosis of erosion. And third, to outline clinical examples that review options to restore lost tooth structure. The authors have included illustrations they hope will be used to improve patient understanding and motivation in the early management of dental erosion.

Bryophyte-Feeders in a Basal Brachyceran Lineage (Diptera: Rhagionidae: Spaniinae): Adult Oviposition Behavior and Changes in the Larval Mouthpart Morphology Accompanied with the Diet Shifts

PubMed Central

Kato, Makoto

2016-01-01

Dipteran larval morphology exhibits overwhelming variety, affected by their diverse feeding habits and habitat use. In particular, larval mouthpart morphology is associated with feeding behavior, providing key taxonomic traits. Despite most larval Brachycera being carnivorous, a basal brachyceran family, Rhagionidae, contains bryophyte-feeding taxa with multiple feeding habits. To elucidate the life history, biology, and morphological evolution of the bryophyte-feeding rhagionids, the larval feeding behavior and morphology, and the adult oviposition behavior of four species belonging to three genera of Spaniinae (Spania Meigen, Litoleptis Chillcott and Ptiolina Zetterstedt) are described. Moreover, changes of the larval morphology associated with the evolution of bryophyte-feeding are traced by molecular phylogenetic analyses. Spania and Litoleptis (thallus-miners of thallose liverworts) share a toothed form of apical mandibular sclerite with an orifice on its dorsal surface, which contrasts to those of the other members of Rhagionidae possessing a blade-like mandibular hook with an adoral groove; whereas, Ptiolina (stem borer of mosses) exhibits a weak groove on the adoral surface of mandible and highly sclerotized maxilla with toothed projections. Based on the larval feeding behavior of the thallus-miners, it is inferred that the toothed mandibles with the dorsal orifice facilitate scraping plant tissue and then imbibing it with a great deal of the sap. A phylogeny indicated that the bryophyte-feeding genera formed a clade with Spaniopsis and was sister to Symphoromyia, which presumably are detritivores. This study indicates that the loss or reduction of adoral mandibular groove and mandibular brush is coincident with the evolution of bryophyte-feeding, and it is subsequently followed by the occurrence of dorsal mandibular orifice and the loss of creeping welts accompanying the evolution of thallus-mining. PMID:27812169

Generation of gear tooth surfaces by application of CNC machines

NASA Technical Reports Server (NTRS)

Litvin, F. L.; Chen, N. X.

1994-01-01

This study will demonstrate the importance of application of computer numerically controlled (CNC) machines in generation of gear tooth surfaces with new topology. This topology decreases gear vibration and will extend the gear capacity and service life. A preliminary investigation by a tooth contact analysis (TCA) program has shown that gear tooth surfaces in line contact (for instance, involute helical gears with parallel axes, worm gear drives with cylindrical worms, etc.) are very sensitive to angular errors of misalignment that cause edge contact and an unfavorable shape of transmission errors and vibration. The new topology of gear tooth surfaces is based on the localization of bearing contact, and the synthesis of a predesigned parabolic function of transmission errors that is able to absorb a piecewise linear function of transmission errors caused by gear misalignment. The report will describe the following topics: description of kinematics of CNC machines with six degrees of freedom that can be applied for generation of gear tooth surfaces with new topology. A new method for grinding of gear tooth surfaces by a cone surface or surface of revolution based on application of CNC machines is described. This method provides an optimal approximation of the ground surface to the given one. This method is especially beneficial when undeveloped ruled surfaces are to be ground. Execution of motions of the CNC machine is also described. The solution to this problem can be applied as well for the transfer of machine tool settings from a conventional generator to the CNC machine. The developed theory required the derivation of a modified equation of meshing based on application of the concept of space curves, space curves represented on surfaces, geodesic curvature, surface torsion, etc. Condensed information on these topics of differential geometry is provided as well.

Remineralization of early enamel caries lesions using different bioactive elements containing toothpastes: An in vitro study.

PubMed

Wang, Yu; Mei, Li; Gong, Lin; Li, Jialing; He, Shaowei; Ji, Yan; Sun, Weibin

2016-09-14

Demineralization can be arrested or reversed when remineralization agents are applied to incipient carious or non-cavitated carious lesions. A large number of therapeutic agents including non-fluoridated products have been developed to promote enamel remineralization. This study aims to evaluate the efficacy of different bioactive elements containing toothpastes in remineralization of artificial enamel lesions. Artificial carious lesions were created on 40 human enamel slabs, and were randomly divided into four groups: (1) control group (no treatment), (2) casein phosphopeptide-amorphous calcium phosphate group (CPP-ACP, GC Tooth Mousse), (3) 8% arginine and calcium carbonate group (ACC, Colgate Sensitive Pro-Relief), (4) calcium sodium phosphosilicate group (CSP, NovaMin®). All samples were subjected to 15 days of pH-cycling. Subsequently, a one-hour acid resistance test was carried out. Surface hardness of the samples was assessed using the Knoop hardness test, and surface morphology and roughness were assessed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Data were analyzed using one-way ANOVA, Tukey's test and paired t test. The three tested toothpastes exhibited a significantly higher remineralization efficacy compared with the control group (P< 0.05 for all). After pH-cycling, the specimens treated with Colgate Sensitive Pro-Relief and NovaMin® showed a significant higher surface hardness (P< 0.001 and P= 0.03, respectively) and lower surface roughness (P< 0.05 for both) compared those treated with GC Tooth Mousse. While after the acid resistance test, all groups showed a significant loss of surface hardness (P< 0.001 for all) and significant increase of surface roughness (P< 0.05). The specimens treated with Colgate Sensitive Pro-Relief and NovaMin® still showed a significant higher surface hardness and lower surface roughness in comparison with those treated with GC Tooth Mousse (P< 0.05 for all). No significant difference was found in surface hardness and roughness between Colgate Sensitive Pro-Relief and NovaMin® during the pH-cycling test and acid resistance test (P= 0.45 and P= 0.83, respectively). Colgate Sensitive Pro-Relief and NovaMin® present an advantage in enhancing remineralization and inhibiting demineralization for early enamel carious lesions in comparison with GC Tooth Mousse.

[Tooth wear, a proposal for an evaluation system].

PubMed

Wetselaar, P; van der Zaag, J; Lobbezoo, F

2011-06-01

The present-day terminology and definitions of tooth wear are not unambiguous. For diagnosing tooth wear, however, it is essential that they are unambiguous. In this article a proposal is presented for a tooth wear evaluation system with simplified definitions. This system consists ofa number of modules and can be used for various aspects of the diagnostic procedure. It can be used for the quantification of tooth wear, both for periodic screening and for the monitoring of tooth wear in individual patients. The scoring of occlusal/incisal tooth wear as well as of non-occlusal/non-incisal tooth wear is possible. The evaluative system is also suitable for determining which type of tooth wear, such as attrition, abrasion and erosion, is most likely to have caused any observed loss of hard tooth tissue.

The pattern of toothwear amongst 12-18-year-old students in a Nigerian population.

PubMed

Ogunyinka, A; Dosumu, O O; Otuyemi, O D

2001-06-01

The purpose of this study was to investigate the pattern of toothwear in the permanent teeth of 12-18-year-old Nigerian students. The study group comprised 176 individuals (67 males and 109 females) who had no carious cavity, restoration or fracture on any of their permanent teeth. Within the group, 86% had tooth surface loss that was limited to enamel and dentine. No statistically significant differences were observed between the sexes. The most commonly affected tooth was the lower first molar, while the occlusal surface was the most frequently involved. One student had toothwear with a predominantly erosive component as a result of frequent ingestion of low pH drinks, while another displayed toothbrush abrasion. Of those with toothwear, two (13.4%) had parafunctional activities. The cause of toothwear in 73.2% of the study population could not be ascertained. Some of it may be connected with the coarse, abrasive diets that many of the students admitted to consuming on a regular basis.

Determination of Principal Curvatures and Contact Ellipse for Profile Crowned Helical Gears

NASA Technical Reports Server (NTRS)

Feng, P.-H.; Litvin, F. L.; Townsend, D. P.; Handschuh, R. F.

1999-01-01

Helical gears with localized bearing contact of tooth surfaces achieved by profile crowning of tooth surfaces are considered. Profile crowning is provided by application of two imaginary rack-cutters with mismatched surfaces. The goal is to determine the dimensions and orientation of the instantaneous contact ellipse that requires the determination of principle curvatures of pinion-gear tooth surfaces. A simplified solution to this problem is proposed based on the approach development for correlation of principal curvatures and directions of generating and generated tooth surfaces. The obtained equations are applied for profile crowning where the normal profiles of the rack-cutters are either a circular arc or a straight line.

Analysis of tooth brushing cycles.

PubMed

Tosaka, Yuki; Nakakura-Ohshima, Kuniko; Murakami, Nozomi; Ishii, Rikako; Saitoh, Issei; Iwase, Yoko; Yoshihara, Akihiro; Ohuchi, Akitsugu; Hayasaki, Haruaki

2014-11-01

The aim of this study was to demonstrate the effectiveness of an analysis of tooth brushing cycles using a system that measures tooth brushing motion and brushing force with an accelerometer and strain tension gage attached to a toothbrush. Mechanical plaque removal with a manual toothbrush remains the primary method of maintaining good oral hygiene for the majority of the population. Because toothbrush motion has not been fully understood, it should be clarified by analysis of tooth brushing cycles. Twenty healthy female dental hygienists participated in this study. Their tooth brushing motions were measured and analyzed using an American Dental Association-approved manual toothbrush to which a three-dimensional (3-D) accelerometer and strain tension gage were attached. 3-D motion and brushing force on the labial surface of the mandibular right central incisor and the lingual surface of the mandibular left first molar were measured, analyzed, and compared. Multilevel linear model analysis was applied to estimate variables and compare motion and forces related to the two tooth surfaces. The analysis of tooth brushing cycles was feasible, and significant differences were detected for durations and 3-D ranges of toothbrush motion as well as brushing force between the two tooth surfaces. The analysis used in this study demonstrated an ability to detect characteristics of tooth brushing motion, showing tooth brushing motion to change depending on the brushed location. These results also suggest that more detailed instructions might be required according to patient's oral condition.

Crowned spur gears - Methods for generation and Tooth Contact Analysis. II - Generation of the pinion tooth surface by a surface of revolution

NASA Technical Reports Server (NTRS)

Litvin, F. L.; Handschuh, R. F.; Zhang, J.

1988-01-01

A method for generation of crowned pinion tooth surfaces using a surface of revolution is developed. The crowned pinion meshes with a regular involute gear and has a prescribed parabolic type of transmission errors when the gears operate in the aligned mode. When the gears are misaligned the transmission error remains parabolic with the maximum level still remaining very small (less than 0.34 arc second for the numerical examples). Tooth Contact Analysis (TCA) is used to simulate the conditions of meshing, determine the transmission error, and the bearing contact.

Metabolic Syndrome and Periodontal Disease Progression in Men

PubMed Central

Kaye, E.K.; Chen, N.; Cabral, H.J.; Vokonas, P.; Garcia, R.I.

2016-01-01

Metabolic syndrome, a cluster of 3 or more risk factors for cardiovascular disease, is associated with periodontal disease, but few studies have been prospective in design. This study’s aim was to determine whether metabolic syndrome predicts tooth loss and worsening of periodontal disease in a cohort of 760 men in the Department of Veterans Affairs Dental Longitudinal Study and Normative Aging Study who were followed up to 33 y from 1981 to 2013. Systolic and diastolic blood pressures were measured with a standard mercury sphygmomanometer. Waist circumference was measured in units of 0.1 cm following a normal expiration. Fasting blood samples were measured in duplicate for glucose, triglyceride, and high-density lipoprotein. Calibrated periodontists served as dental examiners. Periodontal outcome events on each tooth were defined as progression to predefined threshold levels of probing pocket depth (≥5 mm), clinical attachment loss (≥5 mm), mobility (≥0.5 mm), and alveolar bone loss (≥40% of the distance from the cementoenamel junction to the root apex, on radiographs). Hazards ratios (95% confidence intervals) of tooth loss or a periodontitis event were estimated from tooth-level extended Cox proportional hazards regression models that accounted for clustering of teeth within individuals and used time-dependent status of metabolic syndrome. Covariates included age, education, smoking status, plaque level, and initial level of the appropriate periodontal disease measure. Metabolic syndrome as defined by the International Diabetes Federation increased the hazards of tooth loss (1.39; 1.08 to 1.79), pocket depth ≥5 mm (1.37; 1.14 to 1.65), clinical attachment loss ≥5 mm (1.19; 1.00 to 1.41), alveolar bone loss ≥40% (1.25; 1.00 to 1.56), and tooth mobility ≥0.5 mm (1.43; 1.07 to 1.89). The number of positive metabolic syndrome conditions was also associated with each of these outcomes. These findings suggest that the metabolic disturbances that comprise the metabolic syndrome may play a role in the development or worsening of periodontitis. PMID:27025874

Erosion protection conferred by whole human saliva, dialysed saliva, and artificial saliva

NASA Astrophysics Data System (ADS)

Baumann, T.; Kozik, J.; Lussi, A.; Carvalho, T. S.

2016-10-01

During dental erosion, tooth minerals are dissolved, leading to a softening of the surface and consequently to irreversible surface loss. Components from human saliva form a pellicle on the tooth surface, providing some protection against erosion. To assess the effect of different components and compositions of saliva on the protective potential of the pellicle against enamel erosion, we prepared four different kinds of saliva: human whole stimulated saliva (HS), artificial saliva containing only ions (AS), human saliva dialysed against artificial saliva, containing salivary proteins and ions (HS/AS), and human saliva dialysed against deionised water, containing only salivary proteins but no ions (HS/DW). Enamel specimens underwent four cycles of immersion in either HS, AS, HS/AS, HS/DW, or a humid chamber (Ctrl), followed by erosion with citric acid. During the cycling process, the surface hardness and the calcium released from the surface of the specimens were measured. The different kinds of saliva provided different levels of protection, HS/DW exhibiting significantly better protection than all the other groups (p < 0.0001). Different components of saliva, therefore, have different effects on the protective properties of the pellicle and the right proportions of these components in saliva are critical for the ability to form a protective pellicle.

Community social capital and tooth loss in Japanese older people: a longitudinal cohort study

PubMed Central

Koyama, Shihoko; Aida, Jun; Saito, Masashige; Kondo, Naoki; Sato, Yukihiro; Matsuyama, Yusuke; Tani, Yukako; Sasaki, Yuri; Kondo, Katsunori; Ojima, Toshiyuki; Yamamoto, Tatsuo; Tsuboya, Toru; Osaka, Ken

2016-01-01

Objective To date, no study has prospectively examined the association between social capital (SC) in the community and oral health. The aim of this longitudinal cohort study was to examine the association between both community-level and individual-level SC and tooth loss in older Japanese people. Design Prospective cohort study Setting We utilised data from the Japan Gerontological Evaluation Study (JAGES) performed in 2010 and 2013 and conducted in 525 districts. Participants The target population was restricted to non-institutionalised people aged 65 years or older. Participants included 51 280 people who responded to two surveys and who had teeth at baseline. Primary outcome measure The primary outcome measure was loss of remaining teeth, measured by the downward change of any category of remaining teeth, between baseline and follow-up. Results The mean age of the participants was 72.5 years (SD=5.4). During the study period, 8.2% (n=4180) lost one or more of their remaining teeth. Among three community-level SC variables obtained from factor analysis, an indicator of civic participation significantly reduced the risk of tooth loss (OR 0.93; 95% CI 0.88 to 0.99). The individual-level SC variables ‘hobby activity participation’ and ‘sports group participation’ were also associated with a reduced risk of tooth loss (OR 0.88; 95% CI 0.81 to 0.95 and OR 0.90; 95% CI 0.82 to 0.99, respectively). Conclusions Living in a community with rich SC and individuals with good SC is associated with lower incidence of tooth loss among older Japanese people. PMID:27048636

Dental erosion caused by gastroesophageal reflux disease: a case report

PubMed Central

Cengiz, M İnanç; Saraç, Y Şinasi

2009-01-01

Introduction Chronic regurgitation of gastric acids in patients with gastroesophageal reflux disease may cause dental erosion, which can lead in combination with attrition or bruxism to extensive loss of coronal tooth tissue. Case presentation This clinical report describes treatment of severe tooth wear of a gastroesophageal reflux disease patient who is 54-year-old Turkish male patient. After his medical treatment, severe tooth wear, bruxism and decreased vertical dimensions were determined. The vertical dimension was re-established and maxillary and mandibular anterior and posterior teeth were prepared for metal-ceramic restorations. Metal-ceramic fixed partial dentures were fabricated as full mouth restorations for both maxillary and mandibular arches because of splinting all teeth. And then maxillary stabilization splint was fabricated for his bruxism history. Conclusion Significant loss of coronal tooth structure must taken into consideration. Gastroesophageal reflux disease by itself or in combination with attrition, abrasion or bruxism may be responsible for the loss. An extensive diagnostic evaluation is essential for the medical and dental effects of the problem. PMID:19830044

Dental erosion caused by gastroesophageal reflux disease: a case report.

PubMed

Cengiz, Seda; Cengiz, M Inanç; Saraç, Y Sinasi

2009-07-22

Chronic regurgitation of gastric acids in patients with gastroesophageal reflux disease may cause dental erosion, which can lead in combination with attrition or bruxism to extensive loss of coronal tooth tissue. This clinical report describes treatment of severe tooth wear of a gastroesophageal reflux disease patient who is 54-year-old Turkish male patient. After his medical treatment, severe tooth wear, bruxism and decreased vertical dimensions were determined. The vertical dimension was re-established and maxillary and mandibular anterior and posterior teeth were prepared for metal-ceramic restorations. Metal-ceramic fixed partial dentures were fabricated as full mouth restorations for both maxillary and mandibular arches because of splinting all teeth. And then maxillary stabilization splint was fabricated for his bruxism history. Significant loss of coronal tooth structure must taken into consideration. Gastroesophageal reflux disease by itself or in combination with attrition, abrasion or bruxism may be responsible for the loss. An extensive diagnostic evaluation is essential for the medical and dental effects of the problem.

Alveolar ridge reduction after tooth extraction in adolescents: an animal study

PubMed Central

Sun, Zongyang; Herring, Susan W.; Tee, Boon Ching; Gales, Jordan

2013-01-01

Objective The mechanism for tooth extraction induced residual alveolar ridge reduction (RRR) during adolescence is poorly understood. This study investigated the alveolar bone morphology, growth, resorption and functional loading at normal and extraction sites using an adolescent pig model. Design Sixteen 3-month-old pigs were divided into two groups – immediate post-extraction (IE) and 6-week post-extraction (SE). The IE group received an extraction of one deciduous mandibular molar, immediately followed by a final experiment to record masseter muscle EMGs and strains from the buccal surface of the extraction and contralateral non-extraction sites during function (mastication). The SE group was given the same tooth extraction, then kept for 6 weeks before the same final functional recording as the IE group. Both groups also received baseline (pre-extraction) EMGs and fluorescent vital stains 10 and 3 days before the final functional recording. Immediately after the final functional recording, animals were euthanized and alveolar bone specimens from extraction and contralateral non-extraction sites were collected and used to analyze alveolar bone morphology, apposition and resorption based on fluorescent and hematoxylin and eosin stained histological sections. Results At control sites (IE-extraction, IE-non-extraction and SE-non-extraction), the alveolar ridges grew gingivally and buccally. Bone formation characterized the buccal surface and lingual bundle bone, whereas resorption characterized the lingual surface and buccal bundle bone. The SE-extraction sites showed three major alterations: convergence of the buccal and lingual gingival crests, loss of apposition on the lingual bundle bone, and decelerated growth at the entire buccal surface. These alterations likely resulted from redirected crestal growth as part of the socket healing process, loss of tongue pressure to the lingual side of the teeth which normally provides mechanical stimulation for dental arch expansion, and masticatory underloading during the initial post-extraction period, respectively. Conclusions These data indicate that the initial phase of RRR in adolescents is a product of modified growth, not resorption, possibly because of decreased mechanical stimulation at the extraction site. PMID:23380583

Effects of random tooth profile errors on the dynamic behaviors of planetary gears

NASA Astrophysics Data System (ADS)

Xun, Chao; Long, Xinhua; Hua, Hongxing

2018-02-01

In this paper, a nonlinear random model is built to describe the dynamics of planetary gear trains (PGTs), in which the time-varying mesh stiffness, tooth profile modification (TPM), tooth contact loss, and random tooth profile error are considered. A stochastic method based on the method of multiple scales (MMS) is extended to analyze the statistical property of the dynamic performance of PGTs. By the proposed multiple-scales based stochastic method, the distributions of the dynamic transmission errors (DTEs) are investigated, and the lower and upper bounds are determined based on the 3σ principle. Monte Carlo method is employed to verify the proposed method. Results indicate that the proposed method can be used to determine the distribution of the DTE of PGTs high efficiently and allow a link between the manufacturing precision and the dynamical response. In addition, the effects of tooth profile modification on the distributions of vibration amplitudes and the probability of tooth contact loss with different manufacturing tooth profile errors are studied. The results show that the manufacturing precision affects the distribution of dynamic transmission errors dramatically and appropriate TPMs are helpful to decrease the nominal value and the deviation of the vibration amplitudes.

Mössbauer Studies of Stannous Fluoride Reactivity with Synthetic Tooth Enamel - A Model for the Tooth Cavity Protection Actions of Novel Dentifrices

NASA Astrophysics Data System (ADS)

Dénès, Georges; Muntasar, Abdualhafeed; Kozak, Kathy M.; Baig, Arif A.; White, Donald J.

2002-06-01

SnF2 is an important toothpaste ingredient, added for the provision of clinical efficacy for hard and soft tissue diseases and in breath protection. Synthetic calcium hydroxyapatite powders were exposed to liquid supernates (25 w/w% toothpaste water slurries, centrifuged) of Crest Gum Care® (SnF2) dentifrice. One-minute treatments were followed by 3x water washing, centrifugation and lyophilization. Post treatment, powders were analyzed by Mössbauer spectroscopy with 0.5-1 gram of treated apatite powder. Results show that tooth mineral stannous fluoride interactions include: (1) formation of surface reaction products with both Sn(II) and Sn(IV) oxidation states; (2) Sn-F binding on mineral surfaces with no evidence of SnO. The surface binding is, however, not pure Sn-F but contains contributions of other ligands, probably oxygens from surface phosphates or hydroxyl groups. Results also suggest that surface reacted stannous tin is oxidized with time, even when bound as a layer on the tooth surface. This study demonstrates for the first time the presence of Sn-F on tooth enamel post treatment and the contribution of passivation to long term stannous chemistry on tooth surfaces. The study also illustrates the practical applications of the Mössbauer technique.

The influence of shrouded stator cavity flows on multistage compressor performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wellborn, S.R.; Okiishi, T.H.

1999-07-01

Experiments were performed on a low-speed multistage axial-flow compressor to assess the effects of shrouded stator cavity flows on aerodynamic performance. Five configurations, which involved systematic changes in seal-tooth leakage rates and/or elimination of the shrouded stator cavities, were tested. Rig data indicate increasing seal-tooth leakage substantially degraded compressor performance. For every 1 percent increase in seal-tooth clearance-to-span ratio, the decrease in pressure rise was 3 percent and the reduction in efficiency was 1 point. These observed performance penalties are comparable to those commonly reported for rotor and cantilevered stator tip clearance variations. The performance degradation observed with increased leakagemore » was brought about in two distinct ways. First, increasing seal-tooth leakage directly spoiled the near-hub performance of the stator row in which leakage occurred. Second, the altered stator exit flow conditions, caused by increased leakage, impaired the performance of the next downstream stage by decreasing the work input of the rotor and increasing total pressure loss of the stator. These trends caused the performance of downstream stages to deteriorate progressively. Numerical simulations of the test rig stator flow field were also conducted to help resolve important fluid mechanic details associated with the interaction between the primary and cavity flows. Simulation results show that fluid originating in the upstream cavity collected on the stator suction surface when the cavity tangential momentum was low and on the pressure side when it was high. The convection of cavity fluid to the suction surface was a mechanism that reduced stator performance when leakage increased.« less

Removing or Controlling? How Caries Management Impacts on the Lifetime of Teeth.

PubMed

Schwendicke, Falk; Lamont, Thomas; Innes, Nicola

2018-05-24

Historically, traditional carious lesion management focused on the importance of removal of all carious tissue, with little thought to the lesion origins. The surgical removal of any sign of a carious lesion was prioritised with little, or no, consideration to pulp vitality, loss of tooth structure, or caries disease management. This symptomatic approach concentrating on lesions rather than on the cause of the disease, focused on preventing secondary carious lesion development. Early detection and improved understanding of the caries process - that lesion progress can be arrested or slowed - has led to preventive measures and less destructive management as a focus. The choice of lesion management depends on: whether a primary or permanent tooth is involved; which tooth surface(s) is/are involved; whether the lesion is confined to enamel or extends into dentine; the lesion depth, and lesion cleansability. Use of preventive and minimally invasive operative strategies is complicated by the lack of predictable ways of recording lesions' status to allow early detection of failed strategies and early intervention. Because re-restoration usually makes the cavity larger and, consequently, the tooth weaker, the clinician should be certain about initiating the repeat restoration cycle, delaying the first restoration as much as possible. The 3 main principles that support preventing or slowing the repeat restoration cycle are: (1) avoid restoration placement until there is no other option; (2) place them for maximum longevity; (3) if re-restoration is necessary, repair or refurbishment is preferable to replacement of a defective restoration. © 2018 S. Karger AG, Basel.

Diabetes and tooth loss: an analysis of data from the National Health and Nutrition Examination Survey, 2003-2004.

PubMed

Patel, Manthan H; Kumar, Jayanth V; Moss, Mark E

2013-05-01

The authors conducted an analysis of data from the National Health and Nutrition Examination Survey (NHANES) to understand the association between diabetes and tooth loss in the United States. The authors analyzed the oral examination and self-reported diabetes data obtained from the NHANES 2003-2004 cycle and included 2,508 participants representing a civilian, noninstitutionalized U.S. population 50 years and older. The authors calculated the prevalence of edentulism and the number of missing teeth among dentate people, and they used multiple regression analyses to assess the association between diabetes and tooth loss. The prevalence of edentulism was 28 percent and 14 percent among people with and without diabetes, respectively. The multiple logistic regression analysis revealed that people with diabetes were more likely to be edentulous than were those without diabetes (adjusted odds ratio = 2.25; 95 percent confidence interval, 1.19-4.21). Among dentate adults, those with diabetes had a higher number of missing teeth than did adults without diabetes (mean [standard error {SE}] = 9.8 [0.67]), mean [SE] = 6.7 [0.29]); P < .01). These study results revealed that adults with diabetes are at higher risk of experiencing tooth loss and edentulism than are adults without diabetes. One of every five cases of edentulism in the United States is linked to diabetes. Practical Implications. Although the association between diabetes and periodontal disease is well established, health care professionals also need to recognize the risk of tooth loss and its effect on quality of life among people with diabetes.

Infrared light sensor applied to early detection of tooth decay

NASA Astrophysics Data System (ADS)

Benjumea, Eberto; Espitia, José; Díaz, Leonardo; Torres, Cesar

2017-08-01

The approach dentistry to dental care is gradually shifting to a model focused on early detection and oral-disease prevention; one of the most important methods of prevention of tooth decay is opportune diagnosis of decay and reconstruction. The present study aimed to introduce a procedure for early diagnosis of tooth decay and to compare result of experiment of this method with other common treatments. In this setup, a laser emitting infrared light is injected in core of one bifurcated fiber-optic and conduced to tooth surface and with the same bifurcated fiber the radiation reflected for the same tooth is collected and them conduced to surface of sensor that measures thermal and light frequencies to detect early signs of decay below a tooth surface, where demineralization is difficult to spot with x-ray technology. This device will can be used to diagnose tooth decay without any chemicals and rays such as high power lasers or X-rays.

The aetiology and management of localized anterior tooth wear in the young adult.

PubMed

Bishop, K; Briggs, P; Kelleher, M

1994-05-01

This article reviews the aetiology and clinical features of the increasingly common problem of localized loss of anterior tooth tissue in the young adult. The management of the problem is highlighted, with emphasis placed on preservation of the tooth structure and the use of modern materials and techniques.

Refining enamel thickness measurements from B-mode ultrasound images.

PubMed

Hua, Jeremy; Chen, Ssu-Kuang; Kim, Yongmin

2009-01-01

Dental erosion has been growing increasingly prevalent with the rise in consumption of heavy starches, sugars, coffee, and acidic beverages. In addition, various disorders, such as Gastroenterological Reflux Disease (GERD), have symptoms of rapid rates of tooth erosion. The measurement of enamel thickness would be important for dentists to assess the progression of enamel loss from all forms of erosion, attrition, and abrasion. Characterizing enamel loss is currently done with various subjective indexes that can be interpreted in different ways by different dentists. Ultrasound has been utilized since the 1960s to determine internal tooth structure, but with mixed results. Via image processing and enhancement, we were able to refine B-mode dental ultrasound images for more accurate enamel thickness measurements. The mean difference between the measured thickness of the occlusal enamel from ultrasound images and corresponding gold standard CT images improved from 0.55 mm to 0.32 mm with image processing (p = 0.033). The difference also improved from 0.62 to 0.53 mm at the buccal/lingual enamel surfaces, but not significantly (p = 0.38).

The prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Southern China.

PubMed

Wang, Ping; Lin, Huan Cai; Chen, Jian Hong; Liang, Huan You

2010-08-12

Dental erosion has been investigated in developed and developing countries and the prevalence varies considerably in different countries, geographic locations, and age groups. With the lifestyle of the Chinese people changing significantly over the decades, dental erosion has begun to receive more attention. However, the information about dental erosion in China is scarce. The purpose of this study was to explore the prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Guangzhou, Southern China. This cross-sectional survey was performed by two trained, calibrated examiners. A stratified random sample of 12-13-year-old children (774 boys and 725 girls) from 10 schools was examined for dental erosion using the diagnostic criteria of Eccles and the index of O'Sullivan was applied to record the distribution, severity, and amount of the lesions. Data on the socio-economic status, health behaviours, and general health involved in the etiology of dental erosion were obtained from a self-completed questionnaire. The analyses were performed using SPSS software. At least one tooth surface with signs of erosion was found in 416 children (27.3%). The most frequently affected teeth were the central incisors (upper central incisors, 16.3% and 15.9%; lower central incisors, 17.4% and 14.8%). The most frequently affected surface was the incisal or occlusal edge (43.2%). The loss of enamel contour was present in 54.6% of the tooth surfaces with erosion. Of the affected tooth surfaces, 69.3% had greater than one-half of the tooth surface was affected. The results from logistic regression analysis demonstrated that the children who were female, consumed carbonated drinks once a week or more, and those whose mothers were educated to the primary level tended to have more dental erosion. Dental erosion in 12-13-year-old Chinese school children is becoming a significant problem. A strategy of offering preventive care, including more campaigns promoting a healthier lifestyle for those at risk of dental erosion should be conducted in Chinese children and their parents.

The prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Southern China

PubMed Central

2010-01-01

Background Dental erosion has been investigated in developed and developing countries and the prevalence varies considerably in different countries, geographic locations, and age groups. With the lifestyle of the Chinese people changing significantly over the decades, dental erosion has begun to receive more attention. However, the information about dental erosion in China is scarce. The purpose of this study was to explore the prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Guangzhou, Southern China. Methods This cross-sectional survey was performed by two trained, calibrated examiners. A stratified random sample of 12-13-year-old children (774 boys and 725 girls) from 10 schools was examined for dental erosion using the diagnostic criteria of Eccles and the index of O'Sullivan was applied to record the distribution, severity, and amount of the lesions. Data on the socio-economic status, health behaviours, and general health involved in the etiology of dental erosion were obtained from a self-completed questionnaire. The analyses were performed using SPSS software. Results At least one tooth surface with signs of erosion was found in 416 children (27.3%). The most frequently affected teeth were the central incisors (upper central incisors, 16.3% and 15.9%; lower central incisors, 17.4% and 14.8%). The most frequently affected surface was the incisal or occlusal edge (43.2%). The loss of enamel contour was present in 54.6% of the tooth surfaces with erosion. Of the affected tooth surfaces, 69.3% had greater than one-half of the tooth surface was affected. The results from logistic regression analysis demonstrated that the children who were female, consumed carbonated drinks once a week or more, and those whose mothers were educated to the primary level tended to have more dental erosion. Conclusions Dental erosion in 12-13-year-old Chinese school children is becoming a significant problem. A strategy of offering preventive care, including more campaigns promoting a healthier lifestyle for those at risk of dental erosion should be conducted in Chinese children and their parents. PMID:20704718

Iatrogenic Damage to the Periodontium Caused by Periodontal Treatment Procedures

PubMed Central

Latheef, P; Sirajuddin, Syed; Gundapaneni, Veenadharini; MN, Kumuda; Apine, Ashwini

2015-01-01

Periodontitis is an inflammatory disease affecting the periodontium i.e. the tissues that surround and support the teeth. Periodontitis manifests as progressive loss of the alveolar bone around the teeth, and if left untreated, can cause loosening and subsequent loss of teeth. Periodontitis is initiated by microorganisms that adhere to and grow on the tooth's surfaces, besides an over -aggressive immune response against these microorganisms. The primary goal of periodontal therapy is to preserve the natural dentition by accomplishing and preserving a healthy functional periodontium. Many treatment modalities have been introduced to improve the therapeutic result of periodontal treatment which may also damage the periodontiumiatrogenically. PMID:26312087

Bioengineered Tooth Buds Exhibit Features of Natural Tooth Buds.

PubMed

Smith, E E; Angstadt, S; Monteiro, N; Zhang, W; Khademhosseini, A; Yelick, P C

2018-06-01

Tooth loss is a significant health issue currently affecting millions of people worldwide. Artificial dental implants, the current gold standard tooth replacement therapy, do not exhibit many properties of natural teeth and can be associated with complications leading to implant failure. Here we propose bioengineered tooth buds as a superior alternative tooth replacement therapy. We describe improved methods to create highly cellularized bioengineered tooth bud constructs that formed hallmark features that resemble natural tooth buds such as the dental epithelial stem cell niche, enamel knot signaling centers, transient amplifying cells, and mineralized dental tissue formation. These constructs were composed of postnatal dental cells encapsulated within a hydrogel material that were implanted subcutaneously into immunocompromised rats. To our knowledge, this is the first report describing the use of postnatal dental cells to create bioengineered tooth buds that exhibit evidence of these features of natural tooth development. We propose future bioengineered tooth buds as a promising, clinically relevant tooth replacement therapy.

Dental health in antique population of Vinkovci - Cibalae in Croatia (3rd-5th century).

PubMed

Peko, Dunja; Vodanović, Marin

2016-08-01

Roman city Cibalae (Vinkovci) - the birthplace of Roman emperors Valentinian I and Valens was a very well developed urban ares in the late antique what was evidenced by numerous archaeological findings. The aim of this paper is to get insight in dental health of antique population of Cibalae. One hundred individuals with 2041 teeth dated to 3rd - 5th century AD have been analyzed for caries, antemortem tooth loss, periapical diseases and tooth wear. Prevalence of antemortem tooth loss was 4.3% in males, 5.2% in females. Prevalence of caries per tooth was 8.4% in males, 7.0% in females. Compared to other Croatian antique sites, ancient inhabitants of Roman Cibalae had rather good dental health with low caries prevalence and no gender differences. Statistically significant difference was found between males in females in the prevalence of periapical lesions and degree of tooth wear. Periapical lesions were found only in males.

Three-dimensional quantitative analysis of adhesive remnants and enamel loss resulting from debonding orthodontic molar tubes

PubMed Central

2014-01-01

Aims Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. Material and methods Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 μm. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% saline - debonded. Then 3D scanning was repeated. Superimposition and comparison were proceeded and shape alterations of the entire objects were analyzed using specialized computer software. Residual adhesive heights as well as enamel loss depths have been obtained for the entire buccal surfaces. Residual adhesive volume and enamel loss volume have been calculated for every tooth. Results The maximum height of adhesive remaining on enamel surface was 0.76 mm and the volume on particular teeth ranged from 0.047 mm3 to 4.16 mm3. The median adhesive remnant volume was 0.988 mm3. Mean depths of enamel loss for particular teeth ranged from 0.0076 mm to 0.0416 mm. Highest maximum depth of enamel loss was 0.207 mm. Median volume of enamel loss was 0.104 mm3 and maximum volume was 1.484 mm3. Conclusions Blue-light 3D scanning is able to provide direct precise scans of the enamel surface, which can be superimposed in order to calculate shape alterations. Debonding molar tubes leaves a certain amount of adhesive remnants on the enamel, however the interface fracture pattern varies for particular teeth and areas of enamel loss are present as well. PMID:25208969

Three-dimensional quantitative analysis of adhesive remnants and enamel loss resulting from debonding orthodontic molar tubes.

PubMed

Janiszewska-Olszowska, Joanna; Tandecka, Katarzyna; Szatkiewicz, Tomasz; Sporniak-Tutak, Katarzyna; Grocholewicz, Katarzyna

2014-09-10

Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 μm. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% saline - debonded. Then 3D scanning was repeated. Superimposition and comparison were proceeded and shape alterations of the entire objects were analyzed using specialized computer software. Residual adhesive heights as well as enamel loss depths have been obtained for the entire buccal surfaces. Residual adhesive volume and enamel loss volume have been calculated for every tooth. The maximum height of adhesive remaining on enamel surface was 0.76 mm and the volume on particular teeth ranged from 0.047 mm3 to 4.16 mm3. The median adhesive remnant volume was 0.988 mm3. Mean depths of enamel loss for particular teeth ranged from 0.0076 mm to 0.0416 mm. Highest maximum depth of enamel loss was 0.207 mm. Median volume of enamel loss was 0.104 mm3 and maximum volume was 1.484 mm3. Blue-light 3D scanning is able to provide direct precise scans of the enamel surface, which can be superimposed in order to calculate shape alterations. Debonding molar tubes leaves a certain amount of adhesive remnants on the enamel, however the interface fracture pattern varies for particular teeth and areas of enamel loss are present as well.

Beneficial effects of hydroxyapatite on enamel subjected to 30% hydrogen peroxide.

PubMed

Jiang, Tao; Ma, Xiao; Wang, Zhejun; Tong, Hua; Hu, Jiming; Wang, Yining

2008-11-01

To evaluate the effect of combination of hydroxyapatite (HA) and hydrogen peroxide (HP) on color, microhardness and morphology of human tooth enamel. Forty-eight human dental blocks were obtained from 12 pairs of premolars and were randomly divided into four groups. Group DW was treated with distilled water, group HP with 30% HP, group HA+DW with HA mixed with distilled water and group HA+HP with HA mixed with 30% HP. Baseline and final color measurements and microhardness test were carried out before and after bleaching experiments. Two specimens from each group were selected for morphological investigation after final tests. The DeltaE of group HP and HA+HP were significantly higher than those of group DW (p=0.000 and p=0.000) and group HA+DW (p=0.000 and p=0.000). The percentage microhardness loss of group HA+HP was significantly lower than that of group HP (p=0.047), but significantly higher than those of group DW (p=0.000) and group HA+DW (p=0.000). The obvious variation of morphology was only observed on enamel surfaces in group HP. This study suggested that combination of HA and HP was effective in tooth whitening. HA could significantly reduce the microhardness loss of enamel caused by 30% HP and keep enamel surface morphology almost unchanged.

In vivo quantitative evaluation of tooth color with hand-held colorimeter and custom template.

PubMed

Shimada, Kazuki; Kakehashi, Yoshiyuki; Matsumura, Hideo; Tanoue, Naomi

2004-04-01

This article presents a technique for quantitatively evaluating the color of teeth, as well as color change in restorations and tooth surfaces. Through use of a custom template made of a thermoplastic polymer and a dental colorimeter, tooth surface color can be recorded periodically at the same location intraorally.

Biomaterial Selection for Tooth Regeneration

PubMed Central

Yuan, Zhenglin; Nie, Hemin; Wang, Shuang; Lee, Chang Hun; Li, Ang; Fu, Susan Y.; Zhou, Hong

2011-01-01

Biomaterials are native or synthetic polymers that act as carriers for drug delivery or scaffolds for tissue regeneration. When implanted in vivo, biomaterials should be nontoxic and exert intended functions. For tooth regeneration, biomaterials have primarily served as a scaffold for (1) transplanted stem cells and/or (2) recruitment of endogenous stem cells. This article critically synthesizes our knowledge of biomaterial use in tooth regeneration, including the selection of native and/or synthetic polymers, three-dimensional scaffold fabrication, stem cell transplantation, and stem cell homing. A tooth is a complex biological organ. Tooth loss represents the most common organ failure. Tooth regeneration encompasses not only regrowth of an entire tooth as an organ, but also biological restoration of individual components of the tooth including enamel, dentin, cementum, or dental pulp. Regeneration of tooth root represents perhaps more near-term opportunities than the regeneration of the whole tooth. In the adult, a tooth owes its biological vitality, arguably more, to the root than the crown. Biomaterials are indispensible for the regeneration of tooth root, tooth crown, dental pulp, or an entire tooth. PMID:21699433

Survey on Restoration of Endodontically Treated Anterior Teeth: A Questionnaire Based Study

PubMed Central

Ratnakar, P; Bhosgi, Rashmi; Metta, Kiran Kumar; Aggarwal, Kanika; Vinuta, S; Singh, Navneet

2014-01-01

Background: The aim of endodontic and restorative dentistry is the conservation of natural tooth structure. Endodontically treated tooth (ETT) undergoes loss of tooth structure and changes in physical characteristics. Therefore, proper selection of restoration for ETT is mandatory. The clinical approach of restoring ETT needs taking into considerations several issues. However, the best way to restore teeth after root canal treatment has long been and still a controversial subject to debate. Therefore, this study was carried out to detect the frequency of preferred methods of restoring ETT under different conditions. Materials and Methods: A questionnaire was framed and distributed among prosthodontists, endodontist and general practitioners of north India region to find out the frequency of best suitable material and method regarding restoration of ETT. 220 questionnaires were sent by electronic mail out of which 110 were received back. The questionnaire contained different methods of restoration of endodontically treated anterior teeth at different conditions (percentages) of remaining sound tooth structure. Respondents were asked to indicate their preferred method of restoration of those teeth. Results: Results showed that majority of respondents (51.82%) preferred to restore the tooth only with a tooth-color restorative material in condition A. In condition B, majority of respondents preferred to use tooth colored crown (44.55%) and prefabricated post and tooth colored restoration (24.5%). Whereas in condition C, most of the respondents preferred to use a cast post and core/crown (80.91%). Conclusion: From the findings of the present study, it can be concluded that the unrestored ETT is susceptible to fracture, which could lead to loss of tooth and that the maximum preservation of healthy tooth structure and use of restorative materials with mechanical properties similar to dental structure favor greater longevity of tooth restoration complex. PMID:25628482

Tooth enamel surface micro-hardness with dual species Streptococcus biofilm after exposure to Java turmeric (Curcuma xanthorrhiza Roxb.) extract

NASA Astrophysics Data System (ADS)

Isjwara, F. R. G.; Hasanah, S. N.; Utami, Sri; Suniarti, D. F.

2017-08-01

Streptococcus biofilm on tooth surfaces can decrease mouth environment pH, thus causing enamel demineralization that can lead to dental caries. Java Turmeric extract has excellent antibacterial effects and can maintain S. mutans biofilm pH at neutral levels for 4 hours. To analyze the effect of Java Turmeric extract on tooth enamel micro-hardness, the Java Turmeric extract was added on enamel tooth samples with Streptococcus dual species biofilm (S. sanguinis and S. mutans). The micro-hardness of enamel was measured by Knoop Hardness Tester. Results showed that Curcuma xanthorrhiza Roxb. could not maintain tooth enamel surface micro-hardness. It is concluded that Java Turmeric extract ethanol could not inhibit the hardness of enamel with Streptococcus dual species biofilm.

Effects of ultrasonic instrumentation on enamel surfaces with various defects.

PubMed

Kim, S-Y; Kang, M-K; Kang, S-M; Kim, H-E

2018-05-01

The aim of this study was to analyse the enamel damage caused by ultrasonic scaling of teeth with various enamel conditions that are difficult to identify by visual inspection, such as enamel cracks, early caries and resin restorations. In total, 120 tooth surfaces were divided into 4 experimental groups using a quantitative light-induced fluorescence-digital system: sound enamel group, enamel cracks group, early caries group and resin restoration group. A skilled dental hygienist performed ultrasonic scaling under a standardized set of conditions: a ≤ 15° angle between the scaler tip and tooth surface and 40-80 g of lateral pressure at the rate of 12 times/10 s. Following scaling, the depth of enamel damage was measured using a surface profilometer and observed using scanning electron microscopy (SEM). The damage depth was the greatest in the enamel cracks group (37.63 ± 34.42 μm), followed by the early caries group (26.81 ± 8.67 μm), resin restoration group (19.63 ± 6.73 μm) and the sound enamel group (17.00 ± 5.66 μm). The damage depth was significantly deeper in the enamel cracks and early caries groups than in the sound enamel group (P < .05). SEM clearly revealed enamel loss in the enamel cracks, early caries and resin restoration groups. The results of this study suggest that ultrasonic scaling can cause further damage to teeth with enamel cracks, early caries and resin restorations. Therefore, accurate identification of tooth conditions and calculus before the initiation of ultrasonic scaling is necessary to minimize damage. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Relationship between premature loss of primary teeth with oral hygiene, consumption of soft drinks, dental care, and previous caries experience.

PubMed

López-Gómez, Sandra Aremy; Villalobos-Rodelo, Juan José; Ávila-Burgos, Leticia; Casanova-Rosado, Juan Fernando; Vallejos-Sánchez, Ana Alicia; Lucas-Rincón, Salvador Eduardo; Patiño-Marín, Nuria; Medina-Solís, Carlo Eduardo

2016-02-26

We determine the relationship between premature loss of primary teeth and oral hygiene, consumption of soft drinks, dental care and previous caries experience. This study focused on 833 Mexican schoolchildren aged 6-7. We performed an oral examination to determine caries experience and the simplified oral hygiene index. The dependent variable was the prevalence of at least one missing tooth (or indicated for extraction) of the primary dentition; this variable was coded as 0 = no loss of teeth and 1 = at least one lost primary tooth. The prevalence of at least one missing tooth was 24.7% (n = 206) (95% CI = 21.8-27.7). The variables that were associated with the prevalence of tooth loss (p < 0.05) included: the largest number of decayed teeth (OR = 1.11), the largest number of filled teeth (OR = 1.23), the worst oral hygiene (OR = 3.24), a lower frequency of brushing (OR = 1.60), an increased consumption of soda (OR = 1.89) and use of dental care (curative: OR = 2.83, preventive: OR = 1.93). This study suggests that the premature loss of teeth in the primary dentition is associated with oral hygiene, consumption of soft drinks, dental care and previous caries experience in Mexican schoolchildren. These data provide relevant information for the design of preventive dentistry programs.

Regenerative Needs Following Alveolar Ridge Preservation Procedures in Compromised and Noncompromised Extraction Sockets: A Cone Beam Computed Tomography Study.

PubMed

Koutouzis, Theofilos; Lipton, David

2016-01-01

The aim of this study was to evaluate the necessity for additional regenerative procedures following healing of compromised and noncompromised extraction sockets with alveolar ridge preservation procedures through the use of virtual implant imaging software. The cohort was comprised of 87 consecutive patients subjected to a single maxillary tooth extraction with an alveolar ridge preservation procedure for subsequent implant placement. Patients were divided into two main groups based on the integrity of the buccal bone plate following teeth extraction. Patients in the compromised socket (CS) group (n = 52) had partial or complete buccal bone plate loss, and patients in the noncompromised socket (NCS) group (n = 35) exhibited no bone loss of their socket walls following tooth extraction. Following 4 to 6 months of healing, all patients had a cone beam computed tomography (CBCT) study. Root-formed implants were placed virtually in an ideal prosthetic position. The number of implants per group and location (anterior, premolar, molar) exhibiting exposed buccal implant surface was calculated. In the CS group, 5 out of 19 anterior implants (26.3%), 4 out of 14 premolar implants (28.5%), and 7 out of 19 molar implants (36.8%) had exposed buccal surfaces. In the NCS group, 4 out of 9 anterior implants (44.4%), 2 out of 9 premolar implants (22.2%), and 4 out of 17 molar implants (23.5%) had exposed buccal surfaces. There were no statistically significant differences for intragroup and intergroup comparisons (χ² test, P > .05). This study failed to find statistically significant differences in the frequency of implants with exposed buccal surfaces placed virtually, following treatment of compromised and noncompromised sockets. A high proportion (22% to 44%) of sites had implants that potentially needed additional regenerative procedures.

Effect of vital tooth bleaching on solubility and roughness of dental cements.

PubMed

Londono, Jimmy; Abreu, Amara; Nelson, Steve; Hernandez, Jorge; Torres, Carlos; Mettenburg, Donald; Looney, Stephen; Rueggeberg, Frederick

2009-09-01

Vital tooth bleaching may affect properties of dental cements used for fixed prostheses. The purpose of this study was to examine the effect of a combined in-office and at-home bleaching regimen on changes in surface roughness and depth loss of a variety of commercially available dental cements. Five cement classifications were tested: glass ionomer, resin-modified glass ionomer, resin,self-adhesive resin cement, and zinc phosphate. Cements were placed in multiple wells in plastic blocks. After setting,the surface profile of each block was determined, and average roughness and vertical height of cement surface from the specimen holder were recorded. Blocks were water stored (control) or subjected to in-office and at-home bleaching(n=12). Surfaces were rescanned and pre- and posttest parameter changes were calculated. Statistical analysis consisted of Mann-Whitney-Wilcoxon Rank Sum and Student t tests applied to control and bleaching parameterc hanges within the same cements. A family-wise alpha of .05 was maintained by using a Bonferroni-adjusted level of significance preset to .01 per test. Zinc phosphate showed the only significant depth increase (P=.004) from bleaching: 0.9 +/- 0.7 microm deeper than the water-control group. Only resin-modified glass ionomer showed a significant (P=.004) increase in roughness from bleaching; values increased by 0.05 +/- 0.03 microm over the water-control group. In-office and at-home bleaching significantly increased depth loss of zinc phosphate and increased resinmodified glass ionomer roughness. However, the absolute values of differences observed, as compared to the wateronly control, were considered to be clinically insignificant. (J Prosthet Dent 2009;102:148-154)

Social position, social ties and adult's oral health: 13 year cohort study.

PubMed

Vettore, Mario Vianna; Faerstein, Eduardo; Baker, Sarah Ruth

2016-01-01

This study explored different pathways by which social position and social ties influence adult's oral health over a 13-year period. A cohort investigation (Pro-Saúde Study) was conducted of non-faculty civil servants at a university in Rio de Janeiro, Brazil (N=1613). Baseline data collected in 1999 included age, social position, social ties, and access to dental care. Psychological factors and smoking were assessed in 2001, whereas tooth loss and self-rated oral health (SROH) were collected in 2012. A hypothesised model exploring different direct and indirect pathways was developed and tested using structural equation modelling. The model was a good fit to the data and accounted for 40% and 27% of the variance in tooth loss and SROH, respectively. A greater social position was linked to more social ties (β=0.31), health insurance (β=0.48), low psychological distress (β=0.07), less smoking (β=-0.21), more regular dental visiting (β=0.30), less tooth loss (β=-0.44) and better SROH (β=-0.25) over time. Social position (β=0.0005) and social ties (β=-0.0015) were linked indirectly with psychological distress, smoking and tooth loss. Social position was linked indirectly with social ties, psychological distress and SROH (β=-0.0071). Poor social position and weak social ties were important predictors for tooth loss and poor SROH in adults over the 13-year period. Direct and indirect pathways via psychological factors and smoking on the aforementioned relationships were identified, suggesting different areas of intervention to promote adults' oral health. Adult's oral health is influenced by social conditions through direct and indirect pathways, including via psychological factors and smoking. Copyright © 2015. Published by Elsevier Ltd.

The number of missing teeth in people of the Edo period in Japan in the 17th to 19th centuries.

PubMed

Fujita, Hisashi

2012-06-01

The aims of this study were to examine the number of missing teeth in the people of the Edo period (or number of remaining teeth) and to contribute to the 8020 movement proposed in Japan to help people retain 20 or more of their own teeth until the age of 80. The study of dentition in ancient skeletal remains of our ancestors from multiple perspectives can yield information that can contribute to the study of physical anthropology and the leading edge of modern dental research. The materials were 82 excavated individuals (52 males and 30 females) from 1603 to 1868 whose maxillas and mandibles were both examinable. The age and sex were estimated by anthropological methods, and the individuals were divided into five groups. The status of missing teeth was compared between groups, and a chi-square test was used to test significant differences between groups. The rates of tooth loss were examined in the maxillas and mandibles. In the people of the Edo period, many teeth remained in good condition until early to late middle age. There were more remaining teeth in these individuals than in modern-day individuals. However, the Edo people clearly showed increased tooth loss with age. There were no differences in tooth loss by sex. The tooth type with a high rate of tooth loss was posterior teeth, but incisor loss also occurred with ageing. Mandibular canines were most likely to be remaining. The Edo people had more remaining teeth than modern-day society. This finding was unexpected. The notion that "people of long past ages lost more teeth more quickly" does not seem to apply to people in the Edo period in Japan. © 2011 The Gerodontology Society and John Wiley & Sons A/S.

Abutment tooth loss in patients with overdentures.

PubMed

Ettinger, Ronald L; Qian, Fang

2004-06-01

Since the 1960s, the use of natural teeth as overdenture abutments has become part of accepted clinical practice. Several longitudinal studies have been conducted, but tooth loss has not been reported to be a significant problem. The aim of this study was to identify the incidence and causes of tooth loss in a prospective cohort study of subjects wearing overdentures. The study, conducted between 1973 and 1994, evaluated 273 subjects (62.3 percent male) with a mean age of 59.6 years. Of the 273 subjects with 666 abutments, 74 lost 133 abutments. The most common cause of tooth loss was periodontal disease (29.3 percent) followed by periapical lesions (18.8 percent) and caries (16.5 percent). Through logistic regression, the authors found that subjects who lost teeth were more likely to have medical problems that could cause soft-tissue lesions of the oral mucosa, were less likely to use fluoride daily and were less likely to return for yearly recall visits. The authors found 22 vertical fractures in 17 subjects. Chi2 analysis revealed that overdenture teeth in the maxillary arch that were opposed by natural teeth were more likely to experience vertical fractures. In a study that followed up some patients for as long as 22 years, the rate of tooth loss was 20.0 percent. Many of these failures could have been prevented if patients had practiced better oral hygiene. The findings suggest that if a dentist recommends overdenture therapy, the patient needs to be examined regularly to reduce the risk of experiencing caries and periodontal disease. Also, if the abutments are in the maxilla and are opposed by natural teeth, the dentist should consider using thimble crowns to reduce the risk of vertical fractures.

Is oral health a risk for malignant disease?

PubMed

Seymour, Robin A

2010-06-01

Poor oral health has been associated with a variety of systemic diseases. More recent evidence suggests that the extent and severity of periodontal disease and tooth loss may be associated with an increased risk of malignant disease. An association between poor oral health, smoking, increased alcohol consumption as a risk for oral cancer is well established. Associations between oral health and tooth loss with gastric, lung and pancreatic cancers are explored. Some of the associations need further evaluation before patients are warned about their periodontal health increasing the risk of malignant changes elsewhere in the body. The smoking factor may have a commonality linking oral health with an increased risk for malignant disease. This paper reviews the association between oral health (especially the extent and severity of periodontal disease and tooth loss) as a risk for certain malignancies.

Prosthetic contingencies for future tooth loss.

PubMed

Kaldahl, W B; Becker, C M

1985-01-01

Possible contingencies for future natural tooth loss that can and should be built into prostheses have been reviewed. These contingencies provide a measure of security to the patient and the dentist when attempting to maintain teeth that appear to have a guarded prognosis. Without a contingency these questionable teeth would be extracted early in therapy from fear that a completely new prosthesis would have to be made if they were lost at a later time. In maintaining more natural teeth, the patient has better function, more occlusal and vertical support, longer maintenance of the alveolar ridge, more support for the prosthesis, and more remaining teeth to share all the forces. This approach of building in contingencies for future tooth loss allows the patient and the dentist the freedom to attempt therapy on abutments with a guarded prognosis with little financial risk.

Physical and adhesive properties of dental enamel after radiotherapy and bonding of metal and ceramic brackets.

PubMed

Santin, Gabriela Cristina; Palma-Dibb, Regina Guenka; Romano, Fábio Lourenço; de Oliveira, Harley Francisco; Nelson Filho, Paulo; de Queiroz, Alexandra Mussolino

2015-08-01

The increasing success rates for cancer patients treated with radiotherapy and the frequent occurrence of tooth loss during treatment have led to an increased demand for orthodontic treatment after radiotherapy. The aim of this study was to evaluate tooth enamel of irradiated teeth after the bonding and debonding of metal and ceramic brackets. Ten permanent molars were cut into enamel fragments measuring 1 mm(2) and divided into an irradiated group (total dose of 60 Gy) and a nonirradiated group. The fragments were subjected to microshear testing to evaluate whether radiotherapy altered the strength of the enamel. Furthermore, 90 prepared premolars were divided into 6 groups and subgroups (n = 15): group 1, nonirradiated and nonaged; group 2, nonirradiated and aged (thermal cycled); group 3, irradiated and aged; each group was divided into 2 subgroups: metallic and ceramic brackets. After thermal cycling and radiotherapy, the brackets were bonded onto the specimens with Transbond XT (3M Unitek, Monrovia, Calif). After 24 hours, the specimens were subjected to the shear tests. Images of the enamel surfaces were classified using the adhesive remnant index. The composite resin-enamel interface was also evaluated. Enamel fragments subjected to radiation had lower strength than did the nonirradiated samples (P <0.05). The groups and subgroups submitted to radiation and bonded ceramic brackets had the lowest strength values. Groups 1 and 2 with metallic brackets had less adhesive on the surface, whereas groups 1 and 2 with ceramic brackets and group 3 with both metallic and ceramic brackets had more adhesive on the surfaces. On the images of the composite resin-enamel interface, resin tags were more extensive on irradiated tooth enamel. Radiation decreased tooth enamel strength, and the specimens treated with radiotherapy had higher frequencies of adhesive failure between the bracket and the composite resin as well as more extensive tags. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Does erosion progress differently on teeth already presenting clinical signs of erosive tooth wear than on sound teeth? An in vitro pilot trial.

PubMed

Carvalho, Thiago Saads; Baumann, Tommy; Lussi, Adrian

2016-07-07

Erosive tooth wear (ETW) is clinically characterized by a loss of tooth surface, and different enamel depths may have different susceptibility to demineralization. Therefore, the aim of this in vitro pilot study was to assess if the progression of erosive demineralization is faster on teeth already presenting signs of ETW when compared to originally sound teeth. We selected 23 central incisors: 14 were clinically sound (Sound) and 9 presented clinical signs of early erosive tooth wear (ETW-teeth). The teeth were embedded in resin, leaving an uncovered window of native enamel (6.69 ± 2.30 mm(2)) on the incisal half of the labial surface. We measured enamel surface reflection intensity (SRI) initially and after each consecutive erosive challenge (1 % citric acid, total of 4, 8, 12, 16, 20 and 24 min). Calcium released to the citric acid was measured with an atomic absorption spectrometer. We observed higher initial SRI values in ETW-teeth than in Sound teeth (p = 0.007). During in vitro erosive demineralization, we observed that erosion on originally Sound teeth progressed significantly slower (p = 0.033) than on ETW-teeth: SRI decreased by 75 % (from 100 to 25 %) on Sound teeth, and by 89 % (from 100 to 11 %) on ETW-teeth. Calcium release increased during erosion, but presented no significant differences (p = 0.643) between originally Sound (0.031 μmol/mm(2)) and ETW-teeth (0.032 μmol/mm(2)). There was satisfactory correlation between calcium release and rSRI values (r s  = -0.66). The optical reflectometer distinguished originally sound teeth from those with signs of ETW, and the results suggest that acid demineralization progresses differently on teeth already presenting clinical signs of ETW than on sound teeth.

The origin of the bird's beak: new insights from dinosaur incubation periods.

PubMed

Yang, Tzu-Ruei; Sander, P Martin

2018-05-01

The toothless beak of modern birds was considered as an adaption for feeding ecology; however, several recent studies suggested that developmental factors are also responsible for the toothless beak. Neontological and palaeontological studies have progressively uncovered how birds evolved toothless beaks and suggested that the multiple occurrences of complete edentulism in non-avian dinosaurs were the result of selection for specialized diets. Although developmental biology and ecological factors are not mutually exclusive, the conventional hypothesis that ecological factors account for the toothless beak appears insufficient. A recent study on dinosaur incubation period using embryonic teeth posited that tooth formation rate limits developmental speed, constraining toothed dinosaur incubation to slow reptilian rates. We suggest that selection for tooth loss was a side effect of selection for fast embryo growth and thus shorter incubation. This observation would also explain the multiple occurrences of tooth loss and beaks in non-avian dinosaur taxa crownward of Tyrannosaurus Whereas our hypothesis is an observation without any experimental supports, more studies of gene regulation of tooth formation in embryos would allow testing for the trade-off between incubation period and tooth development. © 2018 The Author(s).

Generation of a crowned pinion tooth surface by a surface of revolution

NASA Technical Reports Server (NTRS)

Litvin, F. L.; Zhang, J.; Handschuh, R. F.

1988-01-01

A method of generating crowned pinion tooth surfaces using a surface of revolution is developed. The crowned pinion meshes with a regular involute gear and has a prescribed parabolic type of transmission errors when the gears operate in the aligned mode. When the gears are misaligned the transmission error remains parabolic with the maximum level still remaining very small (less than 0.34 arc sec for the numerical examples). Tooth contact analysis (TCA) is used to simulate the conditions of meshing, determine the transmission error, and determine the bearing contact.

The Ovariectomized Rat as a Model for Studying Alveolar Bone Loss in Postmenopausal Women

PubMed Central

Johnston, Bryan D.; Ward, Wendy E.

2015-01-01

In postmenopausal women, reduced bone mineral density at the hip and spine is associated with an increased risk of tooth loss, possibly due to a loss of alveolar bone. In turn, having fewer natural teeth may lead to compromised food choices resulting in a poor diet that can contribute to chronic disease risk. The tight link between alveolar bone preservation, tooth retention, better nutritional status, and reduced risk of developing a chronic disease begins with the mitigation of postmenopausal bone loss. The ovariectomized rat, a widely used preclinical model for studying postmenopausal bone loss that mimics deterioration of bone tissue in the hip and spine, can also be used to study mineral and structural changes in alveolar bone to develop drug and/or dietary strategies aimed at tooth retention. This review discusses key findings from studies investigating mandible health and alveolar bone in the ovariectomized rat model. Considerations to maximize the benefits of this model are also included. These include the measurement techniques used, the age at ovariectomy, the duration that a rat is studied after ovariectomy and habitual diet consumed. PMID:26060817

Effect of CPP-ACP on the remineralization of acid-eroded human tooth enamel: nanomechanical properties and microtribological behaviour study

NASA Astrophysics Data System (ADS)

Zheng, L.; Zheng, J.; Zhang, Y. F.; Qian, L. M.; Zhou, Z. R.

2013-10-01

Casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP) has been used to enhance tooth remineralization in the dental clinic. But the contribution of CPP-ACP to the remineralization of acid-eroded human tooth enamel is of widespread controversy. To confirm the application potential of CPP-ACP in the remineralization repair of tooth erosion caused by acid-attack, the effect of remineralization in vitro in 2% w/v CPP-ACP solution on the acid-eroded human tooth enamel was investigated in this study. The repair of surface morphology and the improvement of nanomechanical and microtribological properties were characterized with laser confocal scanning microscope, scanning electron microscope, nanoindentation tester and nanoscratch tester. Results showed that a layer of uneven mineral deposits, which were mainly amorphous calcium phosphate (ACP) in all probability, was observed on the acid-eroded enamel surface after remineralization. Compared with the acid-eroded enamel surface, the nanoindentation hardness and Young's modulus of the remineralized enamel surface obviously increased. Both the friction coefficient and wear volume of the acid-eroded enamel surface decreased after remineralization. However, both the nanomechanical and the anti-wear properties of the remineralized enamel surface were still inferior to those of original enamel surface. In summary, tooth damage caused by acid erosion could be repaired by remineralization in CPP-ACP solution, but the repair effect, especially on the nanomechanical and anti-wear properties of the acid-eroded enamel, was limited. These results would contribute to a further exploration of the remineralization potential of CPP-ACP and a better understanding of the remineralization repair mechanism for acid-eroded human tooth enamel.

Tooth Loss and Dental Implant Outcomes - where is dentistry going? A Survey by SIdP, the Italian Society of Periodontology and Implantology.

PubMed

Cairo, Francesco; Landi, Luca; Gatti, Claudio; Rasperini, Giulio; Aimetti, Mario

2018-05-22

Recently, the Italian Society of Periodontology and Implantology (SIdP) committed an extensive survey to evaluate tooth loss and actual success of dental implants in the population. We would share the main outcomes with the present letter. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Determination of real machine-tool settings and minimization of real surface deviation by computerized inspection

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Kuan, Chihping; Zhang, YI

1991-01-01

A numerical method is developed for the minimization of deviations of real tooth surfaces from the theoretical ones. The deviations are caused by errors of manufacturing, errors of installment of machine-tool settings and distortion of surfaces by heat-treatment. The deviations are determined by coordinate measurements of gear tooth surfaces. The minimization of deviations is based on the proper correction of initially applied machine-tool settings. The contents of accomplished research project cover the following topics: (1) Descriptions of the principle of coordinate measurements of gear tooth surfaces; (2) Deviation of theoretical tooth surfaces (with examples of surfaces of hypoid gears and references for spiral bevel gears); (3) Determination of the reference point and the grid; (4) Determination of the deviations of real tooth surfaces at the points of the grid; and (5) Determination of required corrections of machine-tool settings for minimization of deviations. The procedure for minimization of deviations is based on numerical solution of an overdetermined system of n linear equations in m unknowns (m much less than n ), where n is the number of points of measurements and m is the number of parameters of applied machine-tool settings to be corrected. The developed approach is illustrated with numerical examples.

Tooth loss, prosthetic status and treatment needs among industrial workers in Belgaum, Karnataka, India.

PubMed

Patil, Vishal V; Shigli, Kamal; Hebbal, Mamata; Agrawal, Neha

2012-01-01

The health of industrial workers often goes uncared for due to their stressful working conditions, busy schedules and poor economic conditions. A cross-sectional survey was conducted to determine the prevalence of tooth loss, prosthetic status and treatment needs among industrial workers in Belgaum, Karnataka, India according to the criteria described in the World Health Organization (WHO) Oral Health Assessment form (1997). A total of 614 workers participated in the study. Information was obtained regarding their oral hygiene practice. The presence or absence of habits, and the frequency and duration since the last visit to a dentist were recorded followed by clinical examination. Chi-square test was used to determine the association between the variables and tooth loss. There was a statistically significant difference between the number of missing teeth in different age groups, methods of cleaning, smoking habits and visits to the dentist. Regarding prosthetic status, only one worker had a fixed prosthesis in the mandibular arch. The study revealed that tooth loss was associated with oral hygiene practices, habits and visits to the dentist. Poor prosthetic status and high treatment needs were observed. This study emphasized the need for improved dental health awareness and availability of dental facilities to industrial workers.

Mechanical Failure of Endocrowns Manufactured with Different Ceramic Materials: An In Vitro Biomechanical Study.

PubMed

Aktas, Guliz; Yerlikaya, Hatice; Akca, Kivanc

2018-04-01

To evaluate the effect of different silica-based ceramic materials on the mechanical failure behavior of endocrowns used in the restoration of endodontically treated mandibular molar teeth. Thirty-six intact mandibular molar teeth extracted because of a loss of periodontal support received root canal treatment. The teeth were prepared with a central cavity to support the endocrowns, replacing the occlusal surface with mesial-lingual-distal walls. Data acquisition of the prepared tooth surfaces was carried out digitally with a powder-free intraoral scanner. Restoration designs were completed on manufactured restorations from three silicate ceramics: alumina-silicate (control), zirconia-reinforced (Zr-R), and polymer-infiltrated (P-I). Following adhesive cementation, endocrowns were subjected to thermal aging, and then, each specimen was obliquely loaded to record the fracture strength and define the mechanical failure. For the failure definition, the fracture type characteristics were identified, and further analytic measurements were made on the fractured tooth and ceramic structure. Load-to-fracture failure did not differ significantly, and the calculated mean values were 1035.08 N, 1058.33 N, and 1025.00 N for control, Zr-R, and P-I groups, respectively; however, the stiffness of the restoration-tooth complex was significantly higher than that in both test groups. No statistically significant correlation was established in paired comparisons of the failure strength, restorative stiffness, and fractured tooth distance parameters. The failure mode for teeth restored with zirconia-reinforced glass ceramics was identified as non-restorable. The resin interface in the control and P-I groups presented similar adhesive failure behavior. Mechanical failure of endocrown restorations does not significantly differ for silica-based ceramics modified either with zirconia or polymer. © 2016 by the American College of Prosthodontists.

A method of multi-view intraoral 3D measurement

NASA Astrophysics Data System (ADS)

Zhao, Huijie; Wang, Zhen; Jiang, Hongzhi; Xu, Yang; Lv, Peijun; Sun, Yunchun

2015-02-01

In dental restoration, its important to achieve a high-accuracy digital impression. Most of the existing intraoral measurement systems can only measure the tooth from a single view. Therfore - if we are wilng to acquire the whole data of a tooth, the scans of the tooth from multi-direction ad the data stitching based on the features of the surface are needed, which increases the measurement duration and influence the measurement accuracy. In this paper, we introduce a fringe-projection based on multi-view intraoral measurement system. It can acquire 3D data of the occlusal surface, the buccal surface and the lingual surface of a tooth synchronously, by using a senor with three mirrors, which aim at the three surfaces respectively and thus expand the measuring area. The constant relationship of the three mirrors is calibrated before measurement and can help stitch the data clouds acquired through different mirrors accurately. Therefore the system can obtain the 3D data of a tooth without the need to measure it from different directions for many times. Experiments proved the availability and reliability of this miniaturized measurement system.

Formation of oral and pharyngeal dentition in teleosts depends on differential recruitment of retinoic acid signaling

PubMed Central

Gibert, Yann; Bernard, Laure; Debiais-Thibaud, Melanie; Bourrat, Franck; Joly, Jean-Stephane; Pottin, Karen; Meyer, Axel; Retaux, Sylvie; Stock, David W.; Jackman, William R.; Seritrakul, Pawat; Begemann, Gerrit; Laudet, Vincent

2010-01-01

One of the goals of evolutionary developmental biology is to link specific adaptations to changes in developmental pathways. The dentition of cypriniform fishes, which in contrast to many other teleost fish species possess pharyngeal teeth but lack oral teeth, provides a suitable model to study the development of feeding adaptations. Here, we have examined the involvement of retinoic acid (RA) in tooth development and show that RA is specifically required to induce the pharyngeal tooth developmental program in zebrafish. Perturbation of RA signaling at this stage abolished tooth induction without affecting the development of tooth-associated ceratobranchial bones. We show that this inductive event is dependent on RA synthesis from aldh1a2 in the ventral posterior pharynx. Fibroblast growth factor (FGF) signaling has been shown to be critical for tooth induction in zebrafish, and its loss has been associated with oral tooth loss in cypriniform fishes. Pharmacological treatments targeting the RA and FGF pathways revealed that both pathways act independently during tooth induction. In contrast, we find that in Mexican tetra and medaka, species that also possess oral teeth, both oral and pharyngeal teeth are induced independently of RA. Our analyses suggest an evolutionary scenario in which the gene network controlling tooth development obtained RA dependency in the lineage leading to the cypriniforms. The loss of pharyngeal teeth in this group was cancelled out through a shift in aldh1a2 expression, while oral teeth might have been lost ultimately due to deficient RA signaling in the oral cavity.—Gibert, Y., Bernard, L., Debiais-Thibaud, M., Bourrat, F., Joly, J.-S., Pottin, K., Meyer, A., Retaux, S., Stock, D. W., Jackman, W. R., Seritrakul, P., Begemann, G., Laudet, V. Formation of oral and pharyngeal dentition in teleosts depends on differential recruitment of retinoic acid signaling. PMID:20445074

Physical Analysis of the Biomolecules Causing Periodontitis

NASA Astrophysics Data System (ADS)

Shin, Jehun; Lee, Seong Hyeon; Kim, Chai Rin

Periodontitis caused by microorganisms that adhere to and grow on the tooth's surfaces, is an inflammatory diseases causing gum infection. The disease damages the soft tissues that surround and support the teeth and destroys the bone that supports teeth and finally causes tooth loss. An increased risk of stroke and heart attack problems are related to the periodontitis as well. Most bacteria or pathogens attach to gum surface where they form a biofilm. Bacterial cells in biofilms are well protected against antibiotics. The mechanisms of action are still unknown, and it is difficult to control pathogens with antibiotics in biofilm infections and thus the study on the antibiotics is needed. In this research, a number of natural water soluble, small-sized antibiotics molecules and their derivatives are studied. Molecular editing programs such as Gamess, Chemcraft and Avogadro, with an auto-optimization feature that determines the theoretical values of the structure's atomic properties are used to build virtually any molecule with the optimized geometry according to various force field options. The UFF (Universal Force Field) is used for optimizing most molecules.

Minimizing the extra-oral time in autogeneous tooth transplantation: use of computer-aided rapid prototyping (CARP) as a duplicate model tooth.

PubMed

Lee, Seung-Jong; Kim, Euiseong

2012-08-01

The maintenance of the healthy periodontal ligament cells of the root surface of donor tooth and intimate surface contact between the donor tooth and the recipient bone are the key factors for successful tooth transplantation. In order to achieve these purposes, a duplicated donor tooth model can be utilized to reduce the extra-oral time using the computer-aided rapid prototyping (CARP) technique. Briefly, a three-dimensional digital imaging and communication in medicine (DICOM) image with the real dimensions of the donor tooth was obtained from a computed tomography (CT), and a life-sized resin tooth model was fabricated. Dimensional errors between real tooth, 3D CT image model and CARP model were calculated. And extra-oral time was recorded during the autotransplantation of the teeth. The average extra-oral time was 7 min 25 sec with the range of immediate to 25 min in cases which extra-oral root canal treatments were not performed while it was 9 min 15 sec when extra-oral root canal treatments were performed. The average radiographic distance between the root surface and the alveolar bone was 1.17 mm and 1.35 mm at mesial cervix and apex; they were 0.98 mm and 1.26 mm at the distal cervix and apex. When the dimensional errors between real tooth, 3D CT image model and CARP model were measured in cadavers, the average of absolute error was 0.291 mm between real teeth and CARP model. These data indicate that CARP may be of value in minimizing the extra-oral time and the gap between the donor tooth and the recipient alveolar bone in tooth transplantation.

In vitro performance of DIAGNOdent laser fluorescence device for dental calculus detection on human tooth root surfaces.

PubMed

Rams, Thomas E; Alwaqyan, Abdulaziz Y

2017-10-01

This study assessed the reproducibility of a red diode laser device, and its capability to detect dental calculus in vitro on human tooth root surfaces. On each of 50 extracted teeth, a calculus-positive and calculus-free root surface was evaluated by two independent examiners with a low-power indium gallium arsenide phosphide diode laser (DIAGNOdent) fitted with a periodontal probe-like sapphire tip and emitting visible red light at 655 nm wavelength. Laser autofluorescence intensity readings of examined root surfaces were scored on a 0-99 scale, with duplicate assessments performed using the laser probe tip directed both perpendicular and parallel to evaluated tooth root surfaces. Pearson correlation coefficients of untransformed measurements, and kappa analysis of data dichotomized with a >40 autofluorescence intensity threshold, were calculated to assess intra- and inter-examiner reproducibility of the laser device. Mean autofluorescence intensity scores of calculus-positive and calculus-free root surfaces were evaluated with the Student's t -test. Excellent intra- and inter-examiner reproducibility was found for DIAGNOdent laser autofluorescence intensity measurements, with Pearson correlation coefficients above 94%, and kappa values ranging between 0.96 and 1.0, for duplicate readings taken with both laser probe tip orientations. Significantly higher autofluorescence intensity values were measured when the laser probe tip was directed perpendicular, rather than parallel, to tooth root surfaces. However, calculus-positive roots, particularly with calculus in markedly-raised ledges, yielded significantly greater mean DIAGNOdent laser autofluorescence intensity scores than calculus-free surfaces, regardless of probe tip orientation. DIAGNOdent autofluorescence intensity values >40 exhibited a stronger association with calculus (36.6 odds ratio) then measurements of ≥5 (20.1 odds ratio) when the laser probe tip was advanced parallel to root surfaces. Excellent intra- and inter-examiner reproducibility of autofluorescence intensity measurements was obtained with the DIAGNOdent laser fluorescence device on human tooth roots. Calculus-positive root surfaces exhibited significantly greater DIAGNOdent laser autofluorescence than calculus-free tooth roots, even with the laser probe tip directed parallel to root surfaces. These findings provide further in vitro validation of the potential utility of a DIAGNOdent laser fluorescence device for identifying dental calculus on human tooth root surfaces.

Periodontal status, tooth loss and self-reported periodontal problems effects on oral impacts on daily performances, OIDP, in pregnant women in Uganda: a cross-sectional study

PubMed Central

Wandera, Margaret N; Engebretsen, Ingunn M; Rwenyonyi, Charles M; Tumwine, James; Åstrøm, Anne N

2009-01-01

Background An important aim of antenatal care is to improve maternal health- and well being of which oral health is an important part. This study aimed to estimate the prevalence of oral impacts on daily performances (OIDP) during pregnancy, using a locally adapted OIDP inventory, and to document how periodontal status, tooth-loss and reported periodontal problems are related to oral impacts. Methods Pregnant women at about 7 months gestational age who were members of a community based multi-center cluster randomized community trial: PROMISE EBF: Safety and Efficacy of Exclusive Breast feeding in the Era of HIV in Sub-Saharan Africa, were recruited in the district of Mbale, Eastern Uganda between January 2006 and June 2008. A total of 877 women (participation rate 877/886, 98%, mean age 25.6, sd 6.4) completed an interview and 713 (participation rate 713/886, 80.6%, mean age 25.5 sd 6.6) were examined clinically with respect to tooth-loss and according to the Community Periodontal Index, CPI. Results Seven of the original 8 OIDP items were translated into the local language. Cronbach's alpha was 0.85 and 0.80 in urban and rural areas, respectively. The prevalence of oral impacts was 25% in the urban and 30% in the rural area. Corresponding estimates for CPI>0 were 63% and 68%. Adjusted ORs for having any oral impact were 1.1 (95% CI 0.7-1.7), 1.9 (95% CI 1.2-3.1), 1.7 (1.1-2.7) and 2.0 (0.9-4.4) if having respectively, CPI>0, at least one tooth lost, tooth loss in molars and tooth loss in molar-and anterior regions. The Adjusted ORs for any oral impact if reporting periodontal problems ranged from 2.7(95% CI 1.8-4.2) (bad breath) through 8.6(95% CI 5.6-12.9) (chewing problem) to 22.3 (95% CI 13.3-35.9) (toothache). Conclusion A substantial proportion of pregnant women experienced oral impacts. The OIDP impacts were most and least substantial regarding functional- and social concerns, respectively. The OIDP varied systematically with tooth loss in the molar region, reported chewing-and periodontal problems. Pregnant women's oral health should be addressed through antenatal care programs in societies with limited access to regular dental care facilities. PMID:19828031

Reasons for Placement of Restorations on Previously Unrestored Tooth Surfaces by Dental PBRN Dentists

PubMed Central

Nascimento, Marcelle M.; Gordan, Valeria V.; Qvist, Vibeke; Litaker, Mark S.; Rindal, D. Brad; Williams, O.D.; Fellows, Jeffrey L.; Ritchie, Lloyd K.; Mjör, Ivar A.; McClelland, Jocelyn; Gilbert, Gregg H.

2010-01-01

Objective To identify and quantify the reasons for placing restorations on unrestored permanent tooth surfaces and the dental materials used by Dental Practice-Based Research Network (DPBRN; www.DentalPBRN.org) dentists. Methods A total of 229 DPBRN practitioner-investigators collected data on 9,890 consecutive restorations from 5,810 patients. Information included: (1) reasons for restoring; (2) tooth and surfaces restored; and (3) restorative materials employed. Results Primary caries (85%) and non-carious defects (15%), which included abrasion/ abfraction/ erosion lesions and tooth fracture, were the main reasons for placement of restorations. Restorations due to caries were frequently placed on occlusal surfaces (49%), followed by distal, mesial, buccal/facial, lingual/palatal, and incisal surfaces. Amalgam was used for 46% of the molar and 45% of the premolar restorations. Directly placed resin-based composite (RBC) was used for 48% of the molar, 49% of the premolar, and 92% of the anterior restorations. Conclusion Dental caries on occlusal and proximal surfaces of molar teeth are the main reasons for placing restorations on previously unrestored tooth surfaces by DPBRN practitioner-investigators. RBC is the material most commonly used for occlusal and anterior restorations. Amalgam remains the material of choice to restore proximal caries in posterior teeth, although there are significant differences by DPBRN region. PMID:20354094

Rugometric and microtopographic inspection of teeth enamel

NASA Astrophysics Data System (ADS)

Costa, Manuel F.; Pereira, Pedro B.

2013-06-01

The roughness of teeth' enamel is an important parameter in orthodontics. One example is the application in the process of decreasing tooth-size by reducing the interproximal enamel surfaces (stripping) of teeth. In order to achieve smooth surfaces clinicians have been testing various methods and progressively improved this therapeutic technique. The evaluation the surface roughness following teeth interproximal reduction is fundamental in the process. In general tooth' surface is not flat presenting a variety of complex geometries. In this communication we will report on the metrological procedure employed on the rugometric and microtopographic inspection by optical active triangulation of raw and processed (interproximal stripping) tooth surfaces.

Influence of xerostomia on oral health-related quality of life in the elderly: a 5-year longitudinal study.

PubMed

Enoki, Kaori; Matsuda, Ken-Ich; Ikebe, Kazunori; Murai, Shunsuke; Yoshida, Minoru; Maeda, Yoshinobu; Thomson, William Murray

2014-06-01

Xerostomia and tooth loss are major oral health problems in the elderly. The aim of this longitudinal study was to characterize the influence of xerostomia on oral health-related quality of life (OHRQoL) among elderly Japanese people. A total of 99 community-dwelling, independently living individuals aged 60 years and older were interviewed and underwent dental examination at baseline and at a 5-year follow-up. The Oral Health Impact Profile-14 and the Xerostomia Inventory were used to assess OHRQoL and xerostomia severity, respectively. Participants whose xerostomia worsened over the 5-year period had a significantly poorer follow-up OHRQoL. Linear regression models showed that tooth loss and worsening xerostomia were significant predictors of poorer follow-up OHRQoL. Tooth loss and worsening xerostomia result in poorer OHRQoL among older Japanese people. Copyright © 2014 Elsevier Inc. All rights reserved.

Relationship between premature loss of primary teeth with oral hygiene, consumption of soft drinks, dental care, and previous caries experience

PubMed Central

López-Gómez, Sandra Aremy; Villalobos-Rodelo, Juan José; Ávila-Burgos, Leticia; Casanova-Rosado, Juan Fernando; Vallejos-Sánchez, Ana Alicia; Lucas-Rincón, Salvador Eduardo; Patiño-Marín, Nuria; Medina-Solís, Carlo Eduardo

2016-01-01

We determine the relationship between premature loss of primary teeth and oral hygiene, consumption of soft drinks, dental care and previous caries experience. This study focused on 833 Mexican schoolchildren aged 6–7. We performed an oral examination to determine caries experience and the simplified oral hygiene index. The dependent variable was the prevalence of at least one missing tooth (or indicated for extraction) of the primary dentition; this variable was coded as 0 = no loss of teeth and 1 = at least one lost primary tooth. The prevalence of at least one missing tooth was 24.7% (n = 206) (95% CI = 21.8–27.7). The variables that were associated with the prevalence of tooth loss (p < 0.05) included: the largest number of decayed teeth (OR = 1.11), the largest number of filled teeth (OR = 1.23), the worst oral hygiene (OR = 3.24), a lower frequency of brushing (OR = 1.60), an increased consumption of soda (OR = 1.89) and use of dental care (curative: OR = 2.83, preventive: OR = 1.93). This study suggests that the premature loss of teeth in the primary dentition is associated with oral hygiene, consumption of soft drinks, dental care and previous caries experience in Mexican schoolchildren. These data provide relevant information for the design of preventive dentistry programs. PMID:26916132

Gear Fault Detection Effectiveness as Applied to Tooth Surface Pitting Fatigue Damage

NASA Technical Reports Server (NTRS)

Lewicki, David G.; Dempsey, Paula J.; Heath, Gregory F.; Shanthakumaran, Perumal

2009-01-01

A study was performed to evaluate fault detection effectiveness as applied to gear tooth pitting fatigue damage. Vibration and oil-debris monitoring (ODM) data were gathered from 24 sets of spur pinion and face gears run during a previous endurance evaluation study. Three common condition indicators (RMS, FM4, and NA4) were deduced from the time-averaged vibration data and used with the ODM to evaluate their performance for gear fault detection. The NA4 parameter showed to be a very good condition indicator for the detection of gear tooth surface pitting failures. The FM4 and RMS parameters performed average to below average in detection of gear tooth surface pitting failures. The ODM sensor was successful in detecting a significant amount of debris from all the gear tooth pitting fatigue failures. Excluding outliers, the average cumulative mass at the end of a test was 40 mg.

Multiple essential MT1-MMP functions in tooth root formation, dentinogenesis, and tooth eruption

PubMed Central

Wimer, H.F.; Yamada, S.S.; Yang, T.; Holmbeck, K.; Foster, B.L.

2016-01-01

Membrane-type matrix metalloproteinase 1 (MT1-MMP) is a transmembrane zinc-endopeptidase that breaks down extracellular matrix components, including several collagens, during tissue development and physiological remodeling. MT1-MMP-deficient mice (MT1-MMP−/−) feature severe defects in connective tissues, such as impaired growth, osteopenia, fibrosis, and conspicuous loss of molar tooth eruption and root formation. In order to define the functions of MT1-MMP during root formation and tooth eruption, we analyzed the development of teeth and surrounding tissues in the absence of MT1-MMP. In situ hybridization showed that MT1-MMP was widely expressed in cells associated with teeth and surrounding connective tissues during development. Multiple defects in dentoalveolar tissues were associated with loss of MT1-MMP. Root formation was inhibited by defective structure and function of Hertwig's epithelial root sheath (HERS). However, no defect was found in creation of the eruption pathway, suggesting that tooth eruption was hampered by lack of alveolar bone modeling/remodeling coincident with reduced periodontal ligament (PDL) formation and integration with the alveolar bone. Additionally, we identified a significant defect in dentin formation and mineralization associated with the loss of MT1-MMP. To segregate these multiple defects and trace their cellular origin, conditional ablation of MT1-MMP was performed in epithelia and mesenchyme. Mice featuring selective loss of MT1-MMP activity in the epithelium were indistinguishable from wild type mice, and importantly, featured a normal HERS structure and molar eruption. In contrast, selective knock-out of MT1-MMP in Osterix-expressing mesenchymal cells, including osteoblasts and odontoblasts, recapitulated major defects from the global knock-out including altered HERS structure, short roots, defective dentin formation and mineralization, and reduced alveolar bone formation, although molars were able to erupt. These data indicate that MT1-MMP activity in the dental mesenchyme, and not in epithelial-derived HERS, is essential for proper tooth root formation and eruption. In summary, our studies point to an indispensable role for MT1-MMP-mediated matrix remodeling in tooth eruption through effects on bone formation, soft tissue remodeling and organization of the follicle/PDL region. PMID:26780723

New Perspectives on Tooth Wear

PubMed Central

Lucas, Peter W.; Omar, Ridwaan

2012-01-01

Some of the efforts that have been made to document tooth wear are reviewed here with an emphasis on nonhuman mammals, literature with which dentists may not be very familiar. We project a change in research strategy from the description of wear at various scales of measurement towards investigation of the mechanical mechanisms that actually create the texture of a worn surface. These studies should reveal exactly how tooth tissue is lost and what aspects of the structure of dental tissues affect this. The most important aspects of the interaction between the tooth surface and wear particles would appear to be particle size, particle shape, their mechanical properties with respect to those of tooth tissues, and the influence of saliva. PMID:22536239

Measuring the short-term impact of fluoridation cessation on dental caries in Grade 2 children using tooth surface indices.

PubMed

McLaren, Lindsay; Patterson, Steven; Thawer, Salima; Faris, Peter; McNeil, Deborah; Potestio, Melissa; Shwart, Luke

2016-06-01

To examine the short-term impact of fluoridation cessation on children's caries experience measured by tooth surfaces. If there is an adverse short-term effect of cessation, it should be apparent when we focus on smooth tooth surfaces, where fluoride is most likely to have an impact for the age group and time frame considered in this study. We examined data from population-based samples of school children (Grade 2) in two similar cities in the province of Alberta, Canada: Calgary, where cessation occurred in May 2011 and Edmonton where fluoridation remains in place. We analysed change over time (2004/2005 to 2013/2014) in summary data for primary (defs) and permanent (DMFS) teeth for Calgary and Edmonton, for all tooth surfaces and smooth surfaces only. We also considered, for 2013/2014 only, the exposed subsample defined as lifelong residents who reported usually drinking tap water. We observed, across the full sample, an increase in primary tooth decay (mean defs - all surfaces and smooth surfaces) in both cities, but the magnitude of the increase was greater in Calgary (F-cessation) than in Edmonton (F-continued). For permanent tooth decay, when focusing on smooth surfaces among those affected (those with DMFS>0), we observed a non-significant trend towards an increase in Calgary (F-cessation) that was not apparent in Edmonton (F-continued). Trends observed for primary teeth were consistent with an adverse effect of fluoridation cessation on children's tooth decay, 2.5-3 years post-cessation. Trends for permanent teeth hinted at early indication of an adverse effect. It is important that future data collection efforts in the two cities be undertaken, to permit continued monitoring of these trends. © 2016 The Authors. Community Dentistry and Oral Epidemiology Published by John Wiley & Sons Ltd.

A 4-year clinical evaluation of direct composite build-ups for space closure after orthodontic treatment.

PubMed

Demirci, Mustafa; Tuncer, Safa; Öztaş, Evren; Tekçe, Neslihan; Uysal, Ömer

2015-12-01

To evaluate the medium-term clinical performance of direct composite build-ups for diastema closures and teeth recontouring using a nano and a nanohybrid composite in combination with three- or two-step etch-and-rinse adhesives following treatment with fixed orthodontic appliances. A total of 30 patients (mean age, 19.5 years) received 147 direct composite additions for teeth recontouring and diastema closures. A nano and a nanohybrid composite (Filtek Supreme XT and CeramX Duo) were bonded to tooth structure by using a three-step (Scotchbond Multipurpose) or a two-step (XP Bond) etch and rinse adhesive. Ten out of 147 composite build-ups (composite addition) constituted tooth recontouring cases, and the remaining 137 constituted diastema closure cases. The restorations were evaluated by two experienced, calibrated examiners according to modified Ryge criteria at the following time intervals: baseline, 1, 2, 3, and 4 years. The 4-year survival rates were 92.8 % for Filtek Supreme XT/Scotchbond Multi-Purpose Plus and 93 % for CeramX Duo/XP Bond. Only ten restorations failed (5 Filtek Supreme XT and 5 CeramX Duo). Statistical analysis revealed no significant differences between the two composite-adhesive combinations with respect to color match, marginal discoloration, wear/loss of anatomical form, caries formation, marginal adaptation, and surface texture on comparing the five time periods (baseline, 1, 2, 3, and 4 years) The 4-year survival rates in the present study were favorable. The restorations exhibited excellent scores with regard to color match, marginal adaptation, surface texture, marginal discoloration, wear/loss of anatomical form, and caries formation, after 4 years of clinical evaluation. Clinical relevance An alternative clinical approach for correcting discrepancies in tooth size and form, such as performing direct composite restorations following fixed orthodontic treatment, may be an excellent and minimally invasive treatment.

Oral Rehabilitation of Young Adult with Amelogenesis Imperfecta.

PubMed

Leung, Vincent Ws; Low, Bernard; Yang, Yanqi; Botelho, Michael G

2018-05-01

Amelogenesis imperfecta is a heterogeneous group of hereditary disorders that affect the enamel formation of the primary and permanent dentitions while the remaining tooth structure is normal. Appropriate patient care is necessary to prevent adverse effects on dental oral health, dental disfigurement, and psychological well-being. This clinical report presents a 27-year-old Chinese male with amelogenesis imperfecta (AI) and his restorative management. This clinical report presents a 27-year-old Chinese male with AI and his restorative management. Extraoral examination showed a skeletal class III profile and increased lower facial proportion. Intraorally, all the permanent dentition was hypoplastic with noticeable tooth surface loss and a yellow-brown appearance. This was complicated with a mild maloc-clusion and food packing on his posterior teeth. The patient wanted to improve his appearance and masticatory efficiency. Orthodontic treatment was performed to treat the mild malocclu-sion and create physiological interproximal spacing to minimize tooth preparation and facilitate oral hygiene. This report demonstrates how a multidisciplinary approach for the management of AI can achieve a predictable, functional, and esthetic outcome. Orthodontic treatment facilitated a conservative prosthodontic treatment outcome by selectively increasing interproximal space, minimizing tooth preparation, correcting posterior bilateral cross-bite, as well as an anterior reverse overjet and derotation of the canines. This case report demonstrates the effective restoration of AI using a multidisciplinary approach to overcome crowding using a relatively conservative approach.

Porphyromonas gingivalis: An Overview of Periodontopathic Pathogen below the Gum Line

PubMed Central

How, Kah Yan; Song, Keang Peng; Chan, Kok Gan

2016-01-01

Periodontal disease represents a group of oral inflammatory infections initiated by oral pathogens which exist as a complex biofilms on the tooth surface and cause destruction to tooth supporting tissues. The severity of this disease ranges from mild and reversible inflammation of the gingiva (gingivitis) to chronic destruction of connective tissues, the formation of periodontal pocket and ultimately result in loss of teeth. While human subgingival plaque harbors more than 500 bacterial species, considerable research has shown that Porphyromonas gingivalis, a Gram-negative anaerobic bacterium, is the major etiologic agent which contributes to chronic periodontitis. This black-pigmented bacterium produces a myriad of virulence factors that cause destruction to periodontal tissues either directly or indirectly by modulating the host inflammatory response. Here, this review provides an overview of P. gingivalis and how its virulence factors contribute to the pathogenesis with other microbiome consortium in oral cavity. PMID:26903954

Attrition, abrasion, corrosion and abfraction revisited: a new perspective on tooth surface lesions.

PubMed

Grippo, John O; Simring, Marvin; Schreiner, Steven

2004-08-01

The authors propose updated and revised nomenclature, definitions and classification for tooth surface lesions. Their objective is standardization, clarity and clinical utility for the dental practitioner. The article presents a schema of the pathodynamic mechanisms in the formation of tooth surface lesions--three basic physical and chemical mechanisms, their interactions and their dental manifestations. The use of precise definitions will assist the practitioner in determining the etiology of various tooth surface lesions. Understanding the pathodynamic mechanisms and their many possible interactions, as set forth in the schema, will enable the practitioner to make an accurate differential diagnosis and to provide effective prevention and treatment. It also will assist dentists in communicating more effectively with their colleagues as well as with their patients. In addition, the schema helps identify areas in which future research is indicated.

Damping ratio analysis of tooth stability under various simulated degrees of vertical alveolar bone loss and different root types.

PubMed

Ho, Kuo-Ning; Lee, Sheng-Yang; Huang, Haw-Ming

2017-08-03

The purpose of this study was to evaluate the feasibility of using damping ratio (DR) analysis combined with resonance frequency (RF) and periotest (PTV) analyses to provide additional information about natural tooth stability under various simulated degrees of alveolar vertical bone loss and various root types. Three experimental tooth models, including upper central incisor, upper first premolar, and upper first molar were fabricated using Ti6Al4V alloy. In the tooth models, the periodontal ligament and alveolar bone were simulated using a soft lining material and gypsum, respectively. Various degrees of vertical bone loss were simulated by decreasing the surrounding bone level apically from the cementoenamel junction in 2-mm steps incrementally downward for 10 mm. A commercially available RF analyzer was used to measure the RF and DR of impulse-forced vibrations on the tooth models. The results showed that DRs increased as alveolar vertical bone height decreased and had high coefficients of determination in the linear regression analysis. The damping ratio of the central incisor model without a simulated periodontal ligament were 11.95 ± 1.92 and 27.50 ± 0.67% respectively when their bone levels were set at 2 and 10 mm apically from the cementoenamel junction. These values significantly changed to 28.85 ± 2.54% (p = 0.000) and 51.25 ± 4.78% (p = 0.003) when the tooth model was covered with simulated periodontal ligament. Moreover, teeth with different root types showed different DR and RF patterns. Teeth with multiple roots had lower DRs than teeth with single roots. Damping ratio analysis combined with PTV and RF analysis provides more useful information on the assessment of changes in vertical alveolar bone loss than PTV or RF analysis alone.

Long-term neuroplasticity of the face primary motor cortex and adjacent somatosensory cortex induced by tooth loss can be reversed following dental implant replacement in rats.

PubMed

Avivi-Arber, Limor; Lee, Jye-Chang; Sood, Mandeep; Lakschevitz, Flavia; Fung, Michelle; Barashi-Gozal, Maayan; Glogauer, Michael; Sessle, Barry J

2015-11-01

Tooth loss is common, and exploring the neuroplastic capacity of the face primary motor cortex (face-M1) and adjacent primary somatosensory cortex (face-S1) is crucial for understanding how subjects adapt to tooth loss and their prosthetic replacement. The aim was to test if functional reorganization of jaw and tongue motor representations in the rat face-M1 and face-S1 occurs following tooth extraction, and if subsequent dental implant placement can reverse this neuroplasticity. Rats (n = 22) had the right maxillary molar teeth extracted under local and general anesthesia. One month later, seven rats had dental implant placement into healed extraction sites. Naive rats (n = 8) received no surgical treatment. Intracortical microstimulation (ICMS) and recording of evoked jaw and tongue electromyographic responses were used to define jaw and tongue motor representations at 1 month (n = 8) or 2 months (n = 7) postextraction, 1 month postimplant placement, and at 1-2 months in naive rats. There were no significant differences across study groups in the onset latencies of the ICMS-evoked responses (P > 0.05), but in comparison with naive rats, tooth extraction caused a significant (P < 0.05) and sustained (1-2 months) decreased number of ICMS-defined jaw and tongue sites within face-M1 and -S1, and increased thresholds of ICMS-evoked responses in these sites. Furthermore, dental implant placement reversed the extraction-induced changes in face-S1, and in face-M1 the number of jaw sites even increased as compared to naive rats. These novel findings suggest that face-M1 and adjacent face-S1 may play a role in adaptive mechanisms related to tooth loss and their replacement with dental implants. © 2015 Wiley Periodicals, Inc.

Effect of rotary cutting instruments on the resin-tooth interfacial ultra structure: An in vivo study.

PubMed

Sherawat, Sudhir; Tewari, Sanjay; Duhan, Jigyasa; Gupta, Alpa; Singla, Rakesh

2014-12-01

To evaluate the effect of cutting teeth with different types of burs at various speeds on surface topography of tooth surface and interfacial gap formation at resin-tooth interface. The human molars were divided into seven groups: Diamond bur in airrotor (DA) & micromotor (DM), crosscut carbide bur in airrotor (CCA) & micromotor (CCM), plain carbide bur in airrotor (CA) & micromotor (CM) and #600-grit silicon carbide paper (SiC). In five samples from each group Class II box-only cavities were restored. The occlusal surface of four teeth per group was flattened. Two out of four teeth were acid etched. Teeth were subjected for scanning electron microscopy (SEM). Interfacial gap was observed in all groups with no significant difference. SEM observations revealed CA, CCA & DA were coarser than CM, CCM, DM and SiC. SEM of etched tooth surfaces revealed complete removal of amorphous smear layer in CA & CM, partial removal in CCA, CCM, DA & DM and no removal in SiC. Selecting an appropriate bur and its speed may not play an important role in bonding in terms of interfacial gap formation. Variable changes were observed in surface topography with different burs before and after acid etching. Key words:Surface topography, resin-tooth interface, interfacial gap, bonding.

Effect of rotary cutting instruments on the resin-tooth interfacial ultra structure: An in vivo study

PubMed Central

Sherawat, Sudhir; Tewari, Sanjay; Duhan, Jigyasa; Singla, Rakesh

2014-01-01

Objectives: To evaluate the effect of cutting teeth with different types of burs at various speeds on surface topography of tooth surface and interfacial gap formation at resin-tooth interface. Material and Methods: The human molars were divided into seven groups: Diamond bur in airrotor (DA) & micromotor (DM), crosscut carbide bur in airrotor (CCA) & micromotor (CCM), plain carbide bur in airrotor (CA) & micromotor (CM) and #600-grit silicon carbide paper (SiC). In five samples from each group Class II box-only cavities were restored. The occlusal surface of four teeth per group was flattened. Two out of four teeth were acid etched. Teeth were subjected for scanning electron microscopy (SEM). Results: Interfacial gap was observed in all groups with no significant difference. SEM observations revealed CA, CCA & DA were coarser than CM, CCM, DM and SiC. SEM of etched tooth surfaces revealed complete removal of amorphous smear layer in CA & CM, partial removal in CCA, CCM, DA & DM and no removal in SiC. Conclusions: Selecting an appropriate bur and its speed may not play an important role in bonding in terms of interfacial gap formation. Variable changes were observed in surface topography with different burs before and after acid etching. Key words:Surface topography, resin-tooth interface, interfacial gap, bonding. PMID:25674310

Dental abrasion as a cutting process.

PubMed

Lucas, Peter W; Wagner, Mark; Al-Fadhalah, Khaled; Almusallam, Abdulwahab S; Michael, Shaji; Thai, Lidia A; Strait, David S; Swain, Michael V; van Casteren, Adam; Renno, Waleed M; Shekeban, Ali; Philip, Swapna M; Saji, Sreeja; Atkins, Anthony G

2016-06-06

A mammalian tooth is abraded when a sliding contact between a particle and the tooth surface leads to an immediate loss of tooth tissue. Over time, these contacts can lead to wear serious enough to impair the oral processing of food. Both anatomical and physiological mechanisms have evolved in mammals to try to prevent wear, indicating its evolutionary importance, but it is still an established survival threat. Here we consider that many wear marks result from a cutting action whereby the contacting tip(s) of such wear particles acts akin to a tool tip. Recent theoretical developments show that it is possible to estimate the toughness of abraded materials via cutting tests. Here, we report experiments intended to establish the wear resistance of enamel in terms of its toughness and how friction varies. Imaging via atomic force microscopy (AFM) was used to assess the damage involved. Damage ranged from pure plastic deformation to fracture with and without lateral microcracks. Grooves cut with a Berkovich diamond were the most consistent, suggesting that the toughness of enamel in cutting is 244 J m(-2), which is very high. Friction was higher in the presence of a polyphenolic compound, indicating that this could increase wear potential.

Analysis of enamel rod end patterns on tooth surface for personal identification--ameloglyphics.

PubMed

Manjunath, Krishnappa; Sivapathasundharam, Balasundharam; Saraswathi, Thillai R

2012-05-01

Ameloglyphics is the study of enamel rod end patterns on a tooth surface. Our aim was to study the in vivo analysis of enamel rod end patterns on tooth surfaces for personal identification. In this study, the maxillary left canine and 1st premolar of 30 men and 30 women were included. The cellulose acetate peel technique was used to record enamel rod endings on tooth surfaces. Photomicrographs of the acetate peel imprint were subjected to VeriFinger Standard SDK v5.0 software for obtaining enamel rod end patterns. All 120 enamel rod end patterns were subjected to visual analysis and biometric analysis. Biometric analysis revealed that the enamel rod end pattern is unique for each tooth in an individual. It shows both intra- and interindividual variation. Enamel rod end patterns were unique between the male and female subjects. Visual analysis showed that wavy branched subpattern was the predominant subpattern observed among examined teeth. Hence, ameloglyphics is a reliable technique for personal identification. © 2012 American Academy of Forensic Sciences.

Generation of spiral bevel gears with conjugate tooth surfaces and tooth contact analysis

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Tsung, Wei-Jiung; Lee, Hong-Tao

1987-01-01

A new method for generation of spiral bevel gears is proposed. The main features of this method are as follows: (1) the gear tooth surfaces are conjugated and can transform rotation with zero transmission errors; (2) the tooth bearing contact is localized; (3) the center of the instantaneous contact ellipse moves in a plane that has a fixed orientation; (4) the contact normal performs in the process of meshing a parallel motion; (5) the motion of the contact ellipse provides improved conditions of lubrication; and (6) the gears can be manufactured by use of Gleason's equipment.

Selective Removal of Demineralization Using Near Infrared Cross Polarization Reflectance and a Carbon Dioxide Laser.

PubMed

Chan, Kenneth H; Fried, Daniel

2012-02-09

Lasers can ablate/remove tissue in a non-contact mode of operation and a pulsed laser beam does not interfere with the ability to image the tooth surface, therefore lasers are ideally suited for integration with imaging devices for image-guided ablation. Laser energy can be rapidly and efficiently delivered to tooth surfaces using a digitally controlled laser beam scanning system for precise and selective laser ablation with minimal loss of healthy tissues. Under the appropriate irradiation conditions such laser energy can induce beneficial chemical and morphological changes in the walls of the drilled cavity that can increase resistance to further dental decay and produce surfaces with enhanced adhesive properties to restorative materials. Previous studies have shown that images acquired using near-IR transillumination, optical coherence tomography and fluorescence can be used to guide the laser for selective removal of demineralized enamel. Recent studies have shown that NIR reflectance measurements at 1470-nm can be used to obtain images of enamel demineralization with very high contrast. The purpose of this study was to demonstrate that image guided ablation of occlusal lesions can be successfully carried out using a NIR reflectance imaging system coupled with a carbon dioxide laser operating at 9.3-μm with high pulse repetition rates.

Five-year comparative study on conventional and laser-assisted therapy of periimplantitis and periodontitis

NASA Astrophysics Data System (ADS)

Bach, Georg; Neckel, Claus P.

2000-03-01

Numerous groups have recommended the use of the diode laser to decontaminate infected root and implant surfaces. The aim of this study was to show the outcome after laser assisted and conventional therapy of periimplantitis and periodontitis administering approved treatment protocols. Between 1994 and 1999 a total of 50 patients with periimplantitis (20) and periodontitis (30) were treated in two groups each. Clinical, microbiological and radiographic evaluation was performed before and 6, 12, 24, 36, 48 and 60 months after treatment. In addition to the conventional treatment protocol, flap surgery, the tooth or implant surface was decontaminated with a 810 nm diode laser using 1 Watt output for 20 sec (CW mode). All accessible surfaces were decontaminated at the follow up dates. In the periimplantitis group recurrence of the marker bacteria was higher and faster over time for the conventionally operated patients. Also the clinical and radiographic reevaluation showed significantly better results. The laser group of the periodontitis patients also showed significantly better outcome in terms of clinical evaluation, microbiological counts, radiographic evaluation and tooth loss. In comparison to other long term studies our results for the conventional therapy were adequate, the laser assisted therapy brought up significantly better and reproducible results.

3D Simulation Modeling of the Tooth Wear Process.

PubMed

Dai, Ning; Hu, Jian; Liu, Hao

2015-01-01

Severe tooth wear is the most common non-caries dental disease, and it can seriously affect oral health. Studying the tooth wear process is time-consuming and difficult, and technological tools are frequently lacking. This paper presents a novel method of digital simulation modeling that represents a new way to study tooth wear. First, a feature extraction algorithm is used to obtain anatomical feature points of the tooth without attrition. Second, after the alignment of non-attrition areas, the initial homogeneous surface is generated by means of the RBF (Radial Basic Function) implicit surface and then deformed to the final homogeneous by the contraction and bounding algorithm. Finally, the method of bilinear interpolation based on Laplacian coordinates between tooth with attrition and without attrition is used to inversely reconstruct the sequence of changes of the 3D tooth morphology during gradual tooth wear process. This method can also be used to generate a process simulation of nonlinear tooth wear by means of fitting an attrition curve to the statistical data of attrition index in a certain region. The effectiveness and efficiency of the attrition simulation algorithm are verified through experimental simulation.

3D Simulation Modeling of the Tooth Wear Process

PubMed Central

Dai, Ning; Hu, Jian; Liu, Hao

2015-01-01

Severe tooth wear is the most common non-caries dental disease, and it can seriously affect oral health. Studying the tooth wear process is time-consuming and difficult, and technological tools are frequently lacking. This paper presents a novel method of digital simulation modeling that represents a new way to study tooth wear. First, a feature extraction algorithm is used to obtain anatomical feature points of the tooth without attrition. Second, after the alignment of non-attrition areas, the initial homogeneous surface is generated by means of the RBF (Radial Basic Function) implicit surface and then deformed to the final homogeneous by the contraction and bounding algorithm. Finally, the method of bilinear interpolation based on Laplacian coordinates between tooth with attrition and without attrition is used to inversely reconstruct the sequence of changes of the 3D tooth morphology during gradual tooth wear process. This method can also be used to generate a process simulation of nonlinear tooth wear by means of fitting an attrition curve to the statistical data of attrition index in a certain region. The effectiveness and efficiency of the attrition simulation algorithm are verified through experimental simulation. PMID:26241942

Computer-aided design of tooth preparations for automated development of fixed prosthodontics.

PubMed

Yuan, Fusong; Sun, Yuchun; Wang, Yong; Lv, Peijun

2014-01-01

This paper introduces a method to digitally design a virtual model of a tooth preparation of the mandibular first molar, by using the commercial three-dimensional (3D) computer-aided design software packages Geomagic and Imageware, and using the model as an input to automatic tooth preparing system. The procedure included acquisition of 3D data from dentate casts and digital modeling of the shape of the tooth preparation components, such as the margin, occlusal surface, and axial surface. The completed model data were stored as stereolithography (STL) files, which were used in a tooth preparation system to help to plan the trajectory. Meanwhile, the required mathematical models in the design process were introduced. The method was used to make an individualized tooth preparation of the mandibular first molar. The entire process took 15min. Using the method presented, a straightforward 3D shape of a full crown can be obtained to meet clinical needs prior to tooth preparation. © 2013 Published by Elsevier Ltd.

Use of a compact fiber optic spectrometer for spectral feedback during the laser ablation of dental hard tissues and restorative materials

NASA Astrophysics Data System (ADS)

Cheng, Joyce Y.; Fan, Kenneth; Fried, Daniel

2006-02-01

One perceived disadvantage of caries removal using lasers is the loss of the tactile feedback associated with the handpiece. However, alternative methods of acoustic and optical feedback become available with the laser that can be exploited to provide information about the chemical composition of the material ablated, the ablation efficiency and rate, the depth of the incision, and the surface and plume temperature during ablation. Such information can be used to increase the selectivity of ablation, avoid peripheral thermal damage and excessive heat deposition in the tooth, and provide a mechanism of robotic automation. The objective of this study was to test the hypothesis that a compact fiberoptic spectrometer could be used to differentiate between the ablation of sound and carious enamel and dentin and between dental hard tissues and composite. Sound and carious tooth surfaces along with composite restorative materials were scanned with λ=0.355, 2.79 and 9.3 μm laser pulses at irradiation intensities ranging from 0.5-100 J/cm2 and spectra were acquired from λ=250-900-nm using a compact fiber-optic spectrometer. Emission spectra varied markedly with the laser wavelength and pulse duration. Optical feedback was not successful in differentiating between sound and carious enamel and dentin even with the addition of various chromophores to carious lesion areas. However, the spectral feedback was successfully used to differentiate between composites and sound enamel and dentin enabling the selective removal of composite from tooth surfaces using a computer controlled λ=9.3-μm pulsed CO II laser and scanning system.

Invasive cervical resorption and the oro-facial cleft patient: a review and case series.

PubMed

O'Mahony, A; McNamara, C; Ireland, A; Sandy, J; Puryer, J

2017-05-12

Introduction Invasive cervical resorption (ICR) has an unknown aetiology, yet it exhibits very aggressive behaviour compared with typical external root resorption, posing a high risk of tooth loss.Aim To investigate the number of patients at the Dublin Cleft Prosthodontic Department with an oro-facial cleft who experienced ICR and to identify any possible aetiological factors.Materials and method A retrospective investigation of all oro-facial cleft patients treated at the Dublin Cleft Prosthodontic Department, St James's Hospital, Dublin. All patients' clinical and radiological records were reviewed. Patients where tooth loss became inevitable due to Class 4 ICR were analysed.Results From 588 oro-facial cleft patients, 14 (2.38%) patients with ICR were identified. Of these eight (57%) were female and six (43%) were male. Mean age at diagnosis was 28 years (range = 16-49 years). Cleft type: six (42.1%) unilateral cleft lip and palate, eight (57.9%) bilateral cleft lip and palate. Seventeen ICR affected teeth in total, with eleven (65%) maxillary central incisors, two (12%) maxillary lateral incisors, four (23%) maxillary canines, and one (7%) central, lateral and canine affected. Some, (N = 10, 71.4%) presented with ICR resulting in immediate tooth loss. Other patients (N = 4, 28.6%) developed ICR during or following prosthodontic treatment at the Cleft Centre. Tooth loss for this cohort, though not immediate, was inevitable. All had undergone fixed orthodontic appliance treatment and twelve had received dento-alveolar bone grafts. A number (N = 7, 50%) had undergone osteotomy, two (14%) had received night guard vital dental whitening and one had a history of trauma.Conclusions ICR, given its aggressive nature and ill-understood aetiology, poses significant treatment challenges. The most severe form of ICR (Class 4) leads inevitably to tooth loss. The slow-moderate progression of ICR may explain the late presentation found in this study, reinforcing the importance of long-term follow-up of this special dental care group.

Test Tube Tooth: The Next Big Thing.

PubMed

Yadav, Preeti; Tahir, Mohammed; Yadav, Harsh; Sureka, Rakshit; Garg, Aarti

2016-06-01

Unlike some vertebrates and fishes, humans do not have the capacity for tooth regeneration after the loss of permanent teeth. Although artificial replacement with removable dentures, fixed prosthesis and implants is possible through advances in the field of prosthetic dentistry, it would be ideal to recreate a third set of natural teeth to replace lost dentition. For many years now, researchers in the field of tissue engineering have been trying to bioengineer dental tissues as well as whole teeth. In order to attain a whole tooth through dental engineering, that has the same or nearly same biological, mechanical and physical properties of a natural tooth, it's necessary to deal with all the cells and tissues which are concerned with the formation, maintenance and repair of the tooth. In this article we review the steps involved in odontogenesis or organogenesis of a tooth and progress in the bioengineering of a whole tooth.

A randomised clinical study to measure the anti-erosion benefits of a stannous-containing sodium fluoride dentifrice

PubMed Central

West, Nicola; Seong, Joon; Macdonald, Emma; He, Tao; Barker, Matthew; Hooper, Susan

2015-01-01

Background: To compare the enamel protection efficacy of stannous-containing sodium fluoride and sodium monofluorophosphate (MFP)/triclosan dentifrices marketed in India in an in situ erosion model with acidic challenge. Materials and Methods: This randomised and controlled, in situ, supervised, double-blind clinical trial employed a two-treatment, four-period crossover design, wherein subjects wore an appliance fitted with human enamel samples 6 h/day during each 10 day treatment period and swished twice daily with their assigned dentifrice slurry: Oral-B® Pro-Health (maximum 1,000 ppm F as sodium fluoride with stannous chloride) or Colgate® Strong Teeth with Cavity Protection (maximum 1,000 F as sodium MFP and triclosan). Subjects swished with 250 ml of orange juice over a 10 min period after each treatment and twice daily for the acidic erosive challenge. Enamel samples were measured for tooth surface loss using contact profilometry at baseline and day 10. Results: A total of 34 subjects were randomised to treatment; 32 subjects completed the final visit. Baseline profilometry measurements of the specimen surfaces were near zero within ± 0.3 μm, and no statistically significant difference (P > 0.48) on average was observed between the two test dentifrices. At day 10, the stannous-containing dentifrice demonstrated 88% less erosion (P < 0.0001) relative to the MFP/triclosan dentifrice. Estimated medians (95% confidence intervals) were 0.21 μm (0.17, 0.25) for the stannous-containing dentifrice versus 1.66 μm (1.39, 1.99) for the MFP/triclosan dentifrice. Both dentifrices were well-tolerated. Conclusions: Compared with MFP/triclosan toothpaste, a stabilised stannous-containing sodium fluoride dentifrice gave statistically significantly greater protection against tooth enamel surface loss in situ following repeated acid erosive challenge. PMID:26015669

Metabolic syndrome as a risk indicator for periodontal disease and tooth loss.

PubMed

Musskopf, Marta L; Daudt, Luciana D; Weidlich, Patrícia; Gerchman, Fernando; Gross, Jorge L; Oppermann, Rui V

2017-03-01

The aim of the present study was to evaluate the association of metabolic syndrome (MS) with periodontitis (PE) and tooth loss (TL). A cross-sectional study was conducted with 363 individuals who underwent full-mouth periodontal examination, and the association between MS and PE was evaluated considering three outcomes: severe periodontitis, mean probing depth ≥2.4 mm, and mean clinical attachment loss ≥2.0 mm. The prevalence ratio (PR) between MS and PE was calculated using a model adjusted for gender, age, smoking, years of education, and socioeconomic status. The adjusted model showed a PR for severe periodontitis of 1.17 (95 % CI 0.83-1.65). There was no significant association between MS and PE defined as mean probing depth ≥2.4 mm. MS was significantly associated with PE defined as mean attachment loss ≥2 mm in individuals aged 41-60 years (PR 1.47, 95 % CI 1.05-2.06). In addition, MS was associated with TL (>6 teeth) (PR 1.23, 95 % CI 1.02-1.49) for all ages, both in crude and adjusted analyses. We concluded that there is a weak association of MS with both attachment loss and TL. Patients with MS seem to have a higher risk of attachment loss and tooth loss and should be screened for periodontal disease.

Topographic assessment of human enamel surface treated with different topical sodium fluoride agents: Scanning electron microscope consideration.

PubMed

Brar, Gurlal Singh; Arora, Amandeep Singh; Khinda, Vineet Inder Singh; Kallar, Shiminder; Arora, Karuna

2017-01-01

Continuous balanced demineralization and remineralization are natural dynamic processes in enamel. If the balance is interrupted and demineralization process dominates, it may eventually lead to the development of carious lesions in enamel and dentine. Fluoride helps control decay by enhancing remineralization and altering the structure of the tooth, making the surface less soluble. One hundred and twenty sound human permanent incisors randomly and equally distributed into six groups as follows: Group I - Control, II - Sodium fluoride solution, III - Sodium fluoride gel, IV - Sodium fluoride varnish, V - Clinpro Tooth Crème (3M ESPE), and VI-GC Tooth Mousse Plus or MI Paste Plus. The samples were kept in artificial saliva for 12 months, and the topical fluoride agents were applied to the respective sample groups as per the manufacturer instructions. Scanning electron microscope (SEM) evaluation of all the samples after 6 and 12 months was made. Morphological changes on the enamel surface after application of fluoride in SEM revealed the presence of globular precipitate in all treated samples. Amorphous, globular, and crystalline structures were seen on the enamel surface of the treated samples. Clear differences were observed between the treated and untreated samples. Globular structures consisting of amorphous CaF2precipitates, which acted as a fluoride reservoir, were observed on the enamel surface after action of different sodium fluoride agents. CPP-ACPF (Tooth Mousse) and Tricalcium phosphate with fluoride (Clinpro tooth crème) are excellent delivery vehicles available in a slow release amorphous form to localize fluoride at the tooth surface.

Nonlinear dynamics of planetary gears using analytical and finite element models

NASA Astrophysics Data System (ADS)

Ambarisha, Vijaya Kumar; Parker, Robert G.

2007-05-01

Vibration-induced gear noise and dynamic loads remain key concerns in many transmission applications that use planetary gears. Tooth separations at large vibrations introduce nonlinearity in geared systems. The present work examines the complex, nonlinear dynamic behavior of spur planetary gears using two models: (i) a lumped-parameter model, and (ii) a finite element model. The two-dimensional (2D) lumped-parameter model represents the gears as lumped inertias, the gear meshes as nonlinear springs with tooth contact loss and periodically varying stiffness due to changing tooth contact conditions, and the supports as linear springs. The 2D finite element model is developed from a unique finite element-contact analysis solver specialized for gear dynamics. Mesh stiffness variation excitation, corner contact, and gear tooth contact loss are all intrinsically considered in the finite element analysis. The dynamics of planetary gears show a rich spectrum of nonlinear phenomena. Nonlinear jumps, chaotic motions, and period-doubling bifurcations occur when the mesh frequency or any of its higher harmonics are near a natural frequency of the system. Responses from the dynamic analysis using analytical and finite element models are successfully compared qualitatively and quantitatively. These comparisons validate the effectiveness of the lumped-parameter model to simulate the dynamics of planetary gears. Mesh phasing rules to suppress rotational and translational vibrations in planetary gears are valid even when nonlinearity from tooth contact loss occurs. These mesh phasing rules, however, are not valid in the chaotic and period-doubling regions.

Impact of Dental Disorders and its Influence on Self Esteem Levels among Adolescents.

PubMed

Kaur, Puneet; Singh, Simarpreet; Mathur, Anmol; Makkar, Diljot Kaur; Aggarwal, Vikram Pal; Batra, Manu; Sharma, Anshika; Goyal, Nikita

2017-04-01

Self esteem is more of a psychological concept therefore, even the common dental disorders like dental trauma, tooth loss and untreated carious lesions may affect the self esteem thus influencing the quality of life. This study aims to assess the impact of dental disorders among the adolescents on their self esteem level. The present cross-sectional study was conducted among 10 to 17 years adolescents. In order to obtain a representative sample, multistage sampling technique was used and sample was selected based on Probability Proportional to Enrolment size (PPE). Oral health assessment was carried out using WHO type III examination and self esteem was estimated using the Rosenberg Self Esteem Scale score (RSES). The descriptive and inferential analysis of the data was done by using IBM SPSS software. Logistic and linear regression analysis was executed to test the individual association of different independent clinical variables with self esteem. Total sample of 1140 adolescents with mean age of 14.95 ±2.08 and RSES of 27.09 ±3.12 were considered. Stepwise multiple linear regression analysis was applied and best predictors in relation to RSES in the descending order were Dental Health Component (DHC), Aesthetic Component (AC), dental decay {(aesthetic zone), (masticatory zone)}, tooth loss {(aesthetic zone), (masticatory zone)} and anterior fracture of tooth. It was found that various dental disorders like malocclusion, anterior traumatic tooth, tooth loss and untreated decay causes a profound impact on aesthetics and psychosocial behaviour of adolescents, thus affecting their self esteem.

Proper Brushing

MedlinePlus

... bristles along the gumline at a 45-degree angle. Bristles should contact both the tooth surface and the gumline. Gently ... A rolling motion is when the brush makes contact with the gumline and ... a 45-degree angle with bristles contacting the tooth surface and gumline. ...

Functional tooth restoration by next-generation bio-hybrid implant as a bio-hybrid artificial organ replacement therapy

PubMed Central

Oshima, Masamitsu; Inoue, Kaoru; Nakajima, Kei; Tachikawa, Tetsuhiko; Yamazaki, Hiromichi; Isobe, Tomohide; Sugawara, Ayaka; Ogawa, Miho; Tanaka, Chie; Saito, Masahiro; Kasugai, Shohei; Takano-Yamamoto, Teruko; Inoue, Takashi; Tezuka, Katsunari; Kuboki, Takuo; Yamaguchi, Akira; Tsuji, Takashi

2014-01-01

Bio-hybrid artificial organs are an attractive concept to restore organ function through precise biological cooperation with surrounding tissues in vivo. However, in bio-hybrid artificial organs, an artificial organ with fibrous connective tissues, including muscles, tendons and ligaments, has not been developed. Here, we have enveloped with embryonic dental follicle tissue around a HA-coated dental implant, and transplanted into the lower first molar region of a murine tooth-loss model. We successfully developed a novel fibrous connected tooth implant using a HA-coated dental implant and dental follicle stem cells as a bio-hybrid organ. This bio-hybrid implant restored physiological functions, including bone remodelling, regeneration of severe bone-defect and responsiveness to noxious stimuli, through regeneration with periodontal tissues, such as periodontal ligament and cementum. Thus, this study represents the potential for a next-generation bio-hybrid implant for tooth loss as a future bio-hybrid artificial organ replacement therapy. PMID:25116435

Ontogenetic Tooth Reduction in Stenopterygius quadriscissus (Reptilia: Ichthyosauria): Negative Allometry, Changes in Growth Rate, and Early Senescence of the Dental Lamina

PubMed Central

Dick, Daniel G.; Maxwell, Erin E.

2015-01-01

We explore the functional, developmental, and evolutionary processes which are argued to produce tooth reduction in the extinct marine reptile Stenopterygius quadriscissus (Reptilia: Ichthyosauria). We analyze the relationship between mandible growth and tooth size, shape, and count, to establish an ontogenetic trend. The pattern in S. quadriscissus is consistent with hypotheses of tooth size reduction by neutral selection, and this unusual morphology (a functionally edentulous rostrum) was produced by a series of different evolutionary developmental changes that are known for other taxa showing tooth reduction and loss. Specifically, this species evolved functional edentulism by evolutionary changes in the growth allometry of the dentition and by altering growth rates through ontogeny. This observation supports previous hypotheses that S. quadriscissus underwent ontogenetic tooth reduction. Tooth reduction in S. quadriscissus may be caused by unique selective pressures resulting from prey choice and feeding behavior, expanding our current understanding of the mechanisms producing tooth reduction. PMID:26579712

Ontogenetic Tooth Reduction in Stenopterygius quadriscissus (Reptilia: Ichthyosauria): Negative Allometry, Changes in Growth Rate, and Early Senescence of the Dental Lamina.

PubMed

Dick, Daniel G; Maxwell, Erin E

2015-01-01

We explore the functional, developmental, and evolutionary processes which are argued to produce tooth reduction in the extinct marine reptile Stenopterygius quadriscissus (Reptilia: Ichthyosauria). We analyze the relationship between mandible growth and tooth size, shape, and count, to establish an ontogenetic trend. The pattern in S. quadriscissus is consistent with hypotheses of tooth size reduction by neutral selection, and this unusual morphology (a functionally edentulous rostrum) was produced by a series of different evolutionary developmental changes that are known for other taxa showing tooth reduction and loss. Specifically, this species evolved functional edentulism by evolutionary changes in the growth allometry of the dentition and by altering growth rates through ontogeny. This observation supports previous hypotheses that S. quadriscissus underwent ontogenetic tooth reduction. Tooth reduction in S. quadriscissus may be caused by unique selective pressures resulting from prey choice and feeding behavior, expanding our current understanding of the mechanisms producing tooth reduction.

Gear Fault Detection Effectiveness as Applied to Tooth Surface Pitting Fatigue Damage

NASA Technical Reports Server (NTRS)

Lewicki, David G.; Dempsey, Paula J.; Heath, Gregory F.; Shanthakumaran, Perumal

2010-01-01

A study was performed to evaluate fault detection effectiveness as applied to gear-tooth-pitting-fatigue damage. Vibration and oil-debris monitoring (ODM) data were gathered from 24 sets of spur pinion and face gears run during a previous endurance evaluation study. Three common condition indicators (RMS, FM4, and NA4 [Ed. 's note: See Appendix A-Definitions D were deduced from the time-averaged vibration data and used with the ODM to evaluate their performance for gear fault detection. The NA4 parameter showed to be a very good condition indicator for the detection of gear tooth surface pitting failures. The FM4 and RMS parameters perfomu:d average to below average in detection of gear tooth surface pitting failures. The ODM sensor was successful in detecting a significant 8lDOunt of debris from all the gear tooth pitting fatigue failures. Excluding outliers, the average cumulative mass at the end of a test was 40 mg.

Timeframe of socket cortication after tooth extraction: A retrospective radiographic study.

PubMed

Bertl, Kristina; Kukla, Edmund Benjamin; Albugami, Rajaa; Beck, Florian; Gahleitner, André; Stavropoulos, Andreas

2018-01-01

To assess the timeframe between tooth extraction and radiographically detectable socket cortication in humans. Two hundred and fifty patients with a CT scan ≤36 months after tooth extraction were included. First, three orthoradial multiplanar reconstruction slices, representing the major part of the extraction socket, were scored regarding the degree of bone healing as (i) healed, that is, complete/continuous cortication of the socket entrance, or (ii) non-healed. Thereafter, based on the results of all three slices, the stage of cortication of the extraction socket, as one unit, was classified as (i) non-corticated, that is, all three slices judged as non-healed, (ii) partially corticated, that is, 1 or 2 slices judged as non-healed, or (iii) completely corticated, that is, all three slices judged as healed. The possible effect of several independent parameters, that is, age, gender, timeframe between tooth extraction and CT scan, tooth type, extent of radiographic bone loss of the extracted tooth, tooth-gap type, smoking status, presence of any systemic disease, and medication intake, on cortication status was statistically evaluated. Three to 6 months after tooth extraction, 27% of the sockets were judged as non-corticated and 53% were judged as partially corticated. After 9-12 months, >80% of the sockets were corticated, while some incompletely corticated sockets were detected up to 15 months after extraction. Each additional month after tooth extraction contributed significantly to a higher likelihood of a more advanced stage of cortication, while radiographic bone loss ≥75% significantly prolonged cortication time; no other independent variable had a significant effect. The results indicate a considerably long timeframe until complete cortication of an extraction socket, that is, 3-6 months after tooth extraction 3 of 4 sockets were still not completely corticated, and only after 9-12 months, complete cortication was observed in about 80% of the sockets. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Automated Inspection And Precise Grinding Of Gears

NASA Technical Reports Server (NTRS)

Frint, Harold; Glasow, Warren

1995-01-01

Method of precise grinding of spiral bevel gears involves automated inspection of gear-tooth surfaces followed by adjustments of machine-tool settings to minimize differences between actual and nominal surfaces. Similar to method described in "Computerized Inspection of Gear-Tooth Surfaces" (LEW-15736). Yields gears of higher quality, with significant reduction in manufacturing and inspection time.

Methods for monitoring erosion using optical coherence tomography

NASA Astrophysics Data System (ADS)

Chan, Kenneth H.; Chan, Andrew C.; Darling, Cynthia L.; Fried, Daniel

Since optical coherence tomography is well suited for measuring small dimensional changes on tooth surfaces it has great potential for monitoring tooth erosion. The purpose of this study was to explore different approaches for monitoring the erosion of enamel. Application of an acid resistant varnish to protect the tooth surface from erosion has proven effective for providing a reference surface for in vitro studies but has limited potential for in vivo studies. Two approaches which can potentially be used in vivo were investigated. The first approach is to measure the remaining enamel thickness, namely the distance from the tooth surface to the dentinal-enamel junction (DEJ). The second more novel approach is to irradiate the surface with a carbon dioxide laser to create a reference layer which resists erosion. Measuring the remaining enamel thickness proved challenging since the surface roughening and subsurface demineralization that commonly occurs during the erosion process can prevent resolution of the underlying DEJ. The areas irradiated by the laser manifested lower rates of erosion compared to the non-irradiated areas and this method appears promising but it is highly dependent on the severity of the acid challenge.

Impact of crestal and subcrestal implant placement in peri-implant bone: A prospective comparative study

PubMed Central

Pellicer-Chover, Hilario; Peñarrocha-Diago, María; Peñarrocha-Oltra, David; Gomar-Vercher, Sonia; Agustín-Panadero, Rubén

2016-01-01

Background To assess the influence of the crestal or subcrestal placement of implants upon peri-implant bone loss over 12 months of follow-up. Material and Methods Twenty-six patients with a single hopeless tooth were recruited in the Oral Surgery Unit (Valencia University, Valencia, Spain). The patients were randomized into two treatment groups: group A (implants placed at crestal level) or group B (implants placed at subcrestal level). Control visits were conducted by a trained clinician at the time of implant placement and 12 months after loading. A previously established standard protocol was used to compile general data on all patients (sex and age, implant length and diameter, and brushing frequency). Implant success rate, peri-implant bone loss and the treatment of the exposed implant surface were studied. The level of statistical significance was defined as 5% (α=0.05). Results Twenty-three patients (8 males and 15 females, mean age 49.8±11.6 years, range 28-75 years) were included in the final data analyses, while three were excluded. All the included subjects were nonsmokers with a brushing frequency of up to twice a day in 85.7% of the cases. The 23 implants comprised 10 crestal implants and 13 subcrestal implants. After implant placement, the mean bone position with respect to the implant platform in group A was 0.0 mm versus 2.16±0.88 mm in group B. After 12 months of follow-up, the mean bone positions were -0.06±1.11 mm and 0.95±1.50 mm, respectively - this representing a bone loss of 0.06±1.11 mm in the case of the crestal implants and of 1.22±1.06 mm in the case of the subcrestal implants (p=0.014). Four crestal implants and 5 subcrestal implants presented peri-implant bone levels below the platform, leaving a mean exposed treated surface of 1.13 mm and 0.57 mm, respectively. The implant osseointegration success rate at 12 months was 100% in both groups. Conclusions Within the limitations of this study, bone loss was found to be greater in the case of the subcrestal implants, though from the clinical perspective these implants presented bone levels above the implant platform after 12 months of follow-up. Key words:Immediate implants, tooth extraction, dental implants, single-tooth, crestal bone, placement level. PMID:26615504

Computerized Modeling and Loaded Tooth Contact Analysis of Hypoid Gears Manufactured by Face Hobbing Process

NASA Astrophysics Data System (ADS)

Nishino, Takayuki

The face hobbing process has been widely applied in automotive industry. But so far few analytical tools have been developed. This makes it difficult for us to optimize gear design. To settle this situation, this study aims at developing a computerized tool to predict the running performances such as loaded tooth contact pattern, static transmission error and so on. First, based upon kinematical analysis of a cutting machine, a mathematical description of tooth surface generation is given. Second, based upon the theory of gearing and differential geometry, conjugate tooth surfaces are studied. Then contact lines are generated. Third, load distribution along contact lines is formulated. Last, the numerical model is validated by measuring loaded transmission error and loaded tooth contact pattern.

A Review of the Relationship between Tooth Loss, Periodontal Disease, and Cancer

PubMed Central

Meyer, Mara S.; Joshipura, Kaumudi; Giovannucci, Edward; Michaud, Dominique S.

2009-01-01

Recent studies have investigated the association between periodontal disease, tooth loss, and several systemic diseases including cancer, cardiovascular disease, and preterm birth. Periodontal disease, a chronic inflammatory condition, is highly prevalent in adult populations around the world, and may be preventable. Estimates of prevalence vary between races and geographic regions, with a marked increase in the occurrence of periodontal disease with advancing age. Worldwide estimates for the prevalence of severe periodontal disease generally range from 10 to 15 percent. The relationship between oral health and cancer has been examined for a number of specific cancer sites. Several studies have reported associations between periodontal disease or tooth loss and risk of oral, upper gastrointestinal, lung, and pancreatic cancer in different populations. In a number of studies, these associations persisted after adjustment for major risk factors, including cigarette smoking and socioeconomic status. This review provides a summary of these findings, discusses possible biological mechanisms involved, and raises methodological issues related to studying these relationships. PMID:18478344

A review of the relationship between tooth loss, periodontal disease, and cancer.

PubMed

Meyer, Mara S; Joshipura, Kaumudi; Giovannucci, Edward; Michaud, Dominique S

2008-11-01

Recent studies have investigated the association between periodontal disease, tooth loss, and several systemic diseases including cancer, cardiovascular disease, and preterm birth. Periodontal disease, a chronic inflammatory condition, is highly prevalent in adult populations around the world, and may be preventable. Estimates of prevalence vary between races and geographic regions, with a marked increase in the occurrence of periodontal disease with advancing age. Worldwide estimates for the prevalence of severe periodontal disease generally range from 10 to 15%. The relationship between oral health and cancer has been examined for a number of specific cancer sites. Several studies have reported associations between periodontal disease or tooth loss and risk of oral, upper gastrointestinal, lung, and pancreatic cancer in different populations. In a number of studies, these associations persisted after adjustment for major risk factors, including cigarette smoking and socioeconomic status. This review provides a summary of these findings, discusses possible biological mechanisms involved, and raises methodological issues related to studying these relationships.

Current trends in dental implants

PubMed Central

Gaviria, Laura; Salcido, John Paul; Guda, Teja

2014-01-01

Tooth loss is very a very common problem; therefore, the use of dental implants is also a common practice. Although research on dental implant designs, materials and techniques has increased in the past few years and is expected to expand in the future, there is still a lot of work involved in the use of better biomaterials, implant design, surface modification and functionalization of surfaces to improve the long-term outcomes of the treatment. This paper provides a brief history and evolution of dental implants. It also describes the types of implants that have been developed, and the parameters that are presently used in the design of dental implants. Finally, it describes the trends that are employed to improve dental implant surfaces, and current technologies used for the analysis and design of the implants. PMID:24868501

Optical microtopographic inspection of the surface of tooth subjected to stripping reduction

NASA Astrophysics Data System (ADS)

Costa, Manuel F.; Pereira, Pedro B.

2011-05-01

In orthodontics, the decreasing of tooth-size by reducing interproximal enamel surfaces (stripping) of teeth is a common procedure which allows dental alignment with minimal changes in the facial profile and no arch expansion. In order to achieve smooth surfaces, clinicians have been testing various methods and progressively improved this therapeutic technique. In order to evaluate the surface roughness of teeth subject to interproximal reduction through the five most commonly used methods, teeth were inspected by scanning electron microscopy and microtopographically measured using the optical active triangulation based microtopographer MICROTOP.06.MFC. The metrological procedure will be presented as well as the comparative results concluding on the most suitable tooth interproximal reduction method.

The non-canonical BMP and Wnt/β-catenin signaling pathways orchestrate early tooth development

PubMed Central

Yuan, Guohua; Yang, Guobin; Zheng, Yuqian; Zhu, Xiaojing; Chen, Zhi; Zhang, Zunyi; Chen, YiPing

2015-01-01

BMP and Wnt signaling pathways play a crucial role in organogenesis, including tooth development. Despite extensive studies, the exact functions, as well as if and how these two pathways act coordinately in regulating early tooth development, remain elusive. In this study, we dissected regulatory functions of BMP and Wnt pathways in early tooth development using a transgenic noggin (Nog) overexpression model (K14Cre;pNog). It exhibits early arrested tooth development, accompanied by reduced cell proliferation and loss of odontogenic fate marker Pitx2 expression in the dental epithelium. We demonstrated that overexpression of Nog disrupted BMP non-canonical activity, which led to a dramatic reduction of cell proliferation rate but did not affect Pitx2 expression. We further identified a novel function of Nog by inhibiting Wnt/β-catenin signaling, causing loss of Pitx2 expression. Co-immunoprecipitation and TOPflash assays revealed direct binding of Nog to Wnts to functionally prevent Wnt/β-catenin signaling. In situ PLA and immunohistochemistry on Nog mutants confirmed in vivo interaction between endogenous Nog and Wnts and modulation of Wnt signaling by Nog in tooth germs. Genetic rescue experiments presented evidence that both BMP and Wnt signaling pathways contribute to cell proliferation regulation in the dental epithelium, with Wnt signaling also controlling the odontogenic fate. Reactivation of both BMP and Wnt signaling pathways, but not of only one of them, rescued tooth developmental defects in K14Cre;pNog mice, in which Wnt signaling can be substituted by transgenic activation of Pitx2. Our results reveal the orchestration of non-canonical BMP and Wnt/β-catenin signaling pathways in the regulation of early tooth development. PMID:25428587

Selective ablation of carious lesions using an integrated near-IR imaging system and a novel 9.3-μm CO2 Laser

NASA Astrophysics Data System (ADS)

Chan, Kenneth H.; Fried, Nathaniel M.; Fried, Daniel

2018-02-01

Previous studies have shown that reflectance imaging at wavelengths greater than 1200-nm can be used to image demineralization on tooth occlusal surfaces with high contrast and without the interference of stains. In addition, these near-IR imaging systems can be integrated with laser ablation systems for the selective removal of carious lesions. Higher wavelengths, such as 1950-nm, yield higher lesion contrast due to higher water absorption and lower scattering. In this study, a point-to-point scanning system employing diode and fiber lasers operating at 1450, 1860, 1880, and 1950-nm was used to acquire reflected light images of the tooth surface. Artificial lesions were imaged at these wavelengths to determine the highest lesion contrast. Near-IR images at 1880-nm were used to demarcate lesion areas for subsequent selective carious lesion removal using a new compact air-cooled CO2 laser prototype operating at 9.3-μm. The highest lesion contrast was at 1950-nm and the dual NIR/CO2 laser system selectively removed the simulated lesions with a mean loss of only 12-μm of sound enamel.

Caries selective ablation: the handpiece

NASA Astrophysics Data System (ADS)

Hennig, Thomas; Rechmann, Peter; Holtermann, Andreas

1995-05-01

Caries selective ablation is fixed to a window of fluences predicted by the ablation thresholds of carious and healthy dentin, respectively. The aim of the study was to develop a dental handpiece which guarantees homogeneous fluence at the irradiated tooth surface. Furthermore the point of treatment should be cooled down without energy losses due to the cooling system. We suggest the direct coupling of the laser radiation into a laminar stream of liquid, which acts in turn as a lengthened beam guide. The impacts of the laser radiation and of the cooling medium fall exactly into the same point. Hot ablation debris is removed out of the crater by the flush of the water jet. Fluences are constant if the handpiece is used in contact mode or at a distance. Normally the surface of a bare fiber working in contact mode is destroyed after a few shots. Coupling the laser radiation into a stream of liquid prevents this destruction. Putting together the benefits of this special handpiece short overall treatment times seem to be possible. High average power can be applied to the tooth without the threat of thermal damage. Furthermore no time consuming cutting of the fiber prolongs the treatment time.

Improved Prefrontal Activity and Chewing Performance as Function of Wearing Denture in Partially Edentulous Elderly Individuals: Functional Near-Infrared Spectroscopy Study

PubMed Central

Kamiya, Kazunobu; Narita, Noriyuki; Iwaki, Sunao

2016-01-01

The purpose of this study was to elucidate the effects of wearing a denture on prefrontal activity during chewing performance. We specifically examined that activity in 12 elderly edentulous subjects [63.1±6.1 years old (mean ± SD)] and 12 young healthy controls (22.1±2.3 years old) using functional near-infrared spectroscopy (fNIRS) in order to evaluate the quality of prefrontal functionality during chewing performance under the conditions of wearing a denture and tooth loss, and then compared the findings with those of young healthy controls. fNIRS and electromyography were used simultaneously to detect prefrontal and masticatory muscle activities during chewing, while occlusal force and masticatory score were also examined by use of a food intake questionnaire. A significant increase in prefrontal activity was observed during chewing while wearing a denture, which was accompanied by increased masticatory muscle activity, occlusal force, and masticatory score, as compared with the tooth loss condition. Prefrontal activation during chewing while wearing a denture in the elderly subjects was not much different from that in the young controls. In contrast, tooth loss in the elderly group resulted in marked prefrontal deactivation, accompanied by decreased masticatory muscle activity, occlusal force, and masticatory score, as compared with the young controls. We concluded that intrinsic prefrontal activation during chewing with a denture may prevent prefrontal depression induced by tooth loss in elderly edentulous patients. PMID:27362255

Oral health-related quality of life in socially endangered persons in Copenhagen, Denmark.

PubMed

Øzhayat, Esben Boeskov; Østergaard, Peter; Gotfredsen, Klaus

2016-11-01

The aims of this study were to investigate and describe the Oral Health Related Quality of Life (OHRQoL) in a socially endangered group of people and to compare the OHRQoL to other patient groups. About 294 socially endangered persons attending a volunteer clinic in Copenhagen Denmark filled in the OHIP-14 questionnaire. The group was compared in mean score and reported problems to a group of patients with tooth loss and about to have a removable dental prosthesis (RDP), a group with tooth loss about to have a fixed dental prosthesis (FDP) and a control group without tooth loss. Significantly higher OHIP-14 score was seen in the socially endangered group (15.5 (SD 12.6)) compared with the control (1.9 (SD 2.7)) and the FDP group (9.4 (SD 8.2)) but not the RDP group (13.1 (SD 10.5)). This difference was not changed after stratifying in age groups. Problems related to psychological disability, social disability, and handicap were more frequent in the social endangered group than for the other groups. The items pain, tense, diet, relax, life, and function stand out as problems in the socially endangered group compared to the other groups. The OHRQoL is highly impaired in the socially endangered persons and at least to the level of persons with great tooth loss about to have an RDP. The problems seem to be more handicapping in the socially endangered compared with other patient groups known to have high impairment.

Knowledge of consequences of missing teeth in patients attending prosthetic clinic in u.C.h. Ibadan.

PubMed

Dosumu, O O; Ogunrinde, J T; Bamigboye, S A

2014-06-01

Various causes of tooth loss such as caries, trauma, periodontal diseases, and cancer have been documented in the literature. In addition, factors that can modify these causes such as level of education, age and sex have been studied. There is however paucity of information on whether patients or people with missing teeth are aware of the side effects of tooth loss on them or on the remaining teeth. This study investigated the knowledge of consequences of missing teeth among partially edentulous patients in a teaching hospital. Self-administered questionnaires were distributed to the patients to collect information relating to demography, cause and duration of tooth loss, awareness of the consequences of tooth loss and their sources of information. Four clinical conditions including supra-eruption, mastication, teeth drifting, and facial collapse were used to assess the level of awareness of consequences of missing teeth. Two hundred and three participants were included in the study. Their mean age was 45.5±1.8 years. There was no significant difference between the knowledge of the consequences of missing teeth and sex or on level of education (p(·) 0.05). Dentists constituted the largest source of information to these patients (25.6%) while the media constituted the least (0.5%). The result of this study showed poor knowledge of the consequences of missing teeth among partially edentulous patients and the media that should be of assistance were equally unaware, signifying urgent need for public awareness on this subject.

Detecting gear tooth fracture in a high contact ratio face gear mesh

NASA Technical Reports Server (NTRS)

Zakrajsek, James J.; Handschuh, Robert F.; Lewicki, David G.; Decker, Harry J.

1995-01-01

This paper summarized the results of a study in which three different vibration diagnostic methods were used to detect gear tooth fracture in a high contact ratio face gear mesh. The NASA spiral bevel gear fatigue test rig was used to produce unseeded fault, natural failures of four face gear specimens. During the fatigue tests, which were run to determine load capacity and primary failure mechanisms for face gears, vibration signals were monitored and recorded for gear diagnostic purposes. Gear tooth bending fatigue and surface pitting were the primary failure modes found in the tests. The damage ranged from partial tooth fracture on a single tooth in one test to heavy wear, severe pitting, and complete tooth fracture of several teeth on another test. Three gear fault detection techniques, FM4, NA4*, and NB4, were applied to the experimental data. These methods use the signal average in both the time and frequency domain. Method NA4* was able to conclusively detect the gear tooth fractures in three out of the four fatigue tests, along with gear tooth surface pitting and heavy wear. For multiple tooth fractures, all of the methods gave a clear indication of the damage. It was also found that due to the high contact ratio of the face gear mesh, single tooth fractures did not significantly affect the vibration signal, making this type of failure difficult to detect.

Material Behavior At The Extreme Cutting Edge In Bandsawing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarwar, Mohammed; Haider, Julfikar; Persson, Martin

2011-01-17

In recent years, bandsawing has been widely accepted as a favourite option for metal cutting off operations where the accuracy of cut, good surface finish, low kerf loss, long tool life and high material removal rate are required. Material removal by multipoint cutting tools such as bandsaw is a complex mechanism owing to the geometry of the bandsaw tooth (e.g., limited gullet size, tooth setting etc.) and the layer of material removed or undeformed chip thickness or depth of cut (5 {mu}m-50 {mu}m) being smaller than or equal to the cutting edge radius (5 {mu}m-15 {mu}m). This situation can leadmore » to inefficient material removal in bandsawing. Most of the research work are concentrated on the mechanics of material removal by single point cutting tool such as lathe tool. However, such efforts are very limited in multipoint cutting tools such as in bandsaw. This paper presents the fundamental understanding of the material behaviour at the extreme cutting edge of bandsaw tooth, which would help in designing and manufacturing of blades with higher cutting performance and life. ''High Speed Photography'' has been carried out to analyse the material removal process at the extreme cutting edge of bandsaw tooth. Geometric model of chip formation mechanisms based on the evidences found during ''High Speed Photography'' and ''Quick Stop'' process is presented. Wear modes and mechanism in bimetal and carbide tipped bandsaw teeth are also presented.« less

Surface variations affecting human dental enamel studied using nanomechanical and chemical analysis

NASA Astrophysics Data System (ADS)

Dickinson, Michelle Emma

The enamel surface is the interface between the tooth and its ever changing oral environment. Cavity (caries) formation and extrinsic tooth staining are due, respectively, to degradation of the enamel structure under low pH conditions and interactions between salivary pellicle and dietary elements. Both of these occur at the enamel surface and are caused by the local environment changing the chemistry of the surface. The results can be detrimental to the enamel's mechanical integrity and aesthetics. Incipient carious lesions are the precursor to caries and form due to demineralisation of enamel. These carious lesions are a reversible structure where ions (e.g. Ca2+, F -) can diffuse in (remineralisation) to preserve the tooth's structural integrity. This investigation used controlled in vitro demineralisation and remineralisation to study artificial carious lesion formation and repair. The carious lesions were cross-sectioned and characterised using nanoindentation, electron probe micro-analysis and time of flight secondary ion mass spectrometry. Mechanical and chemical maps showed the carious lesion had a significantly reduced hardness and elastic modulus, and the calcium and phosphate content was lower than in sound enamel. Fluoride based remineralisation treatments gave a new phase (possibly fluorohydroxyapatite) within the lesion with mechanical properties higher than sound enamel. The acquired salivary pellicle is a protein-rich film formed by the physisorption of organic molecules in saliva onto the enamel surface. Its functions include lubrication during mastication and chemical protection. However, pellicle proteins react with dietary elements such as polyphenols (tannins in tea) causing a brown stain. This study has used in vitro dynamic nanoindentation and atomic force microscopy to examine normal and stained pellicles formed in vivo. The effects of polyphenols on the pellicle's mechanical properties and morphology have been studied. It was found that the initial adsorption of proteins occurred within 30 seconds of exposure to the oral cavity; fully mature pellicles develop in 2 hours. Polyphenol staining resulted in substantial changes in the morphology and mechanical properties of the pellicle. Specifically, staining gives pellicles consisting of large globules with high surface adhesion and a high loss tangent. These changes help explain why extrinsic stains are difficult to remove abrasively.

Automatic method of analysis of OCT images in the assessment of the tooth enamel surface after orthodontic treatment with fixed braces

PubMed Central

2014-01-01

Introduction Fixed orthodontic appliances, despite years of research and development, still raise a lot of controversy because of its potentially destructive influence on enamel. Therefore, it is necessary to quantitatively assess the condition and therein the thickness of tooth enamel in order to select the appropriate orthodontic bonding and debonding methodology as well as to assess the quality of enamel after treatment and clean-up procedure in order to choose the most advantageous course of treatment. One of the assessment methods is computed tomography where the measurement of enamel thickness and the 3D reconstruction of image sequences can be performed fully automatically. Material and method OCT images of 180 teeth were obtained from the Topcon 3D OCT-2000 camera. The images were obtained in vitro by performing sequentially 7 stages of treatment on all the teeth: before any interference into enamel, polishing with orthodontic paste, etching and application of a bonding system, orthodontic bracket bonding, orthodontic bracket removal, cleaning off adhesive residue. A dedicated method for the analysis and processing of images involving median filtering, mathematical morphology, binarization, polynomial approximation and the active contour method has been proposed. Results The obtained results enable automatic measurement of tooth enamel thickness in 5 seconds using the Core i5 CPU M460 @ 2.5GHz 4GB RAM. For one patient, the proposed method of analysis confirms enamel thickness loss of 80 μm (from 730 ± 165 μm to 650 ± 129 μm) after polishing with paste, enamel thickness loss of 435 μm (from 730 ± 165 μm to 295 ± 55 μm) after etching and bonding resin application, growth of a layer having a thickness of 265 μm (from 295 ± 55 μm to 560 ± 98 μm after etching) which is the adhesive system. After removing an orthodontic bracket, the adhesive residue was 105 μm and after cleaning it off, the enamel thickness was 605 μm. The enamel thickness before and after the whole treatment decreased by about 125 μm. Conclusions This paper presents an automatic quantitative method for the assessment of tooth enamel thickness. This method has proven to be an effective diagnostic tool that allows evaluation of the surface and cross section of tooth enamel after orthodontic treatment with fixed thin-arched braces and proper selection of the methodology and course of treatment. PMID:24755213

Influence of tooth brushing on adhesion strength of orthodontic brackets bonded to porcelain.

PubMed

Durgesh, Bangalore H; Alhijji, Saleh; Hashem, Mohamed I; Al Kheraif, AbdulAziz A; Durgesh, Pavithra; Elsharawy, Mohamed; Vallittu, Pekka K

2016-09-28

Adhesive resin composite, which is used to bond orthodontic bracket to tooth surface is exposed to the influence of wear by tooth brushing and wear may influence loosening of the bracket. The aim of this study was to evaluate in vitro the effect of tooth brushing on the adhesion strength of orthodontic brackets bonded to surface treated porcelain. A total of 90 glazed porcelain fused to metal facets (PFM) were randomly assigned into 3 groups according to the surface treatment to be received. Group 1 was conditioned with hydrofluoric acid (HF), group 2 conditioned with grit-blasting (GB) and group 3 conditioned with tribochemical silica coating (RC). The groups were evaluated for surface roughness (Ra) before and after surface treatment. Next, 15 samples from each group were subjected to brushing and remaining 15 samples served as the baseline (n=15). Adhesion strength (shear bond strength)was recorded using a universal testing machine. Data collected were analyzed by ANOVA and Tukey's multiple comparison post hoc analysis. Tooth brushing decreased the bond strength in all groups. The highest adhesion strength (baseline and after brushing) was observed in group 3 (26.8 ± 1.77 MPa and 23.57 ± 1.02 MPa) and the lowest was found in group 1 (9.6 ± 1.5 MPa and 5.87 ± 0.77 MPa). Group 3 specimens exhibited the highest Ra (1.24 ± 0.08). It was found that tooth brushing of the exposed adhesive resin composite at the bracket-bonding substrate interface lowers the bonding strength regardless of the surface treatment of the substrate.

Surface changes of enamel after brushing with charcoal toothpaste

NASA Astrophysics Data System (ADS)

Pertiwi, U. I.; Eriwati, Y. K.; Irawan, B.

2017-08-01

The aim of this study was to determine the surface roughness changes of tooth enamel after brushing with charcoal toothpaste. Thirty specimens were brushed using distilled water (the first group), Strong® Formula toothpaste (the second group), and Charcoal® Formula toothpaste for four minutes and 40 seconds (equivalent to one month) and for 14 minutes (equivalent to three months) using a soft fleece toothbrush with a mass of 150 gr. The roughness was measured using a surface roughness tester, and the results were tested with repeated ANOVA test and one-way ANOVA. The value of the surface roughness of tooth enamel was significantly different (p<0.05) after brushing for an equivalent of one month and an equivalent of three months. Using toothpaste containing charcoal can increase the surface roughness of tooth enamel.

A basis for solid modeling of gear teeth with application in design and manufacture

NASA Technical Reports Server (NTRS)

Huston, Ronald L.; Mavriplis, Dimitrios; Oswald, Fred B.; Liu, Yung Sheng

1992-01-01

A new approach to modeling gear tooth surfaces is discussed. A computer graphics solid modeling procedure is used to simulate the tooth fabrication process. This procedure is based on the principles of differential geometry that pertain to envelopes of curves and surfaces. The procedure is illustrated with the modeling of spur, helical, bevel, spiral bevel, and hypoid gear teeth. Applications in design and manufacturing are discussed. Extensions to nonstandard tooth forms, to cams, and to rolling element bearings are proposed.

A Basis for Solid Modeling of Gear Teeth with Application in Design and Manufacture

NASA Technical Reports Server (NTRS)

Huston, Ronald L.; Mavriplis, Dimitrios; Oswald, Fred B.; Liu, Yung Sheng

1994-01-01

This paper discusses a new approach to modeling gear tooth surfaces. A computer graphics solid modeling procedure is used to simulate the tooth fabrication processes. This procedure is based on the principles of differential geometry that pertain to envelopes of curves and surfaces. The procedure is illustrated with the modeling of spur, helical, bevel, spiral bevel and hypoid gear teeth. Applications in design and manufacturing arc discussed. Extensions to nonstandard tooth forms, to cams, and to rolling element hearings are proposed.

Factors related to tooth loss due to dental caries among workers in an industrial estates in Thailand.

PubMed

Chatrchaiwiwatana, Supaporn; Ratanasiri, Amornrat; Jaidee, Jeeratip; Soontorn, Surasak

2012-11-01

The present study aimed to evaluate the prevalence and factors related to tooth loss due to dental caries among workers in industrial estates in Pathumthani and Phranakhorn Si Ayutthaya provinces in central Thailand. The present study utilized quantitative and qualitative methodologies. A quantitative study was done using a cross-sectional analytic method with a sample group of 457 adults (283 males; 174 females) between 19 and 53 years. Data were obtained through an oral examination and oral health behavior questionnaire. Data analyses were done using descriptive, bivariate and multivariable logistic regression statistics. In-depth interviews were used to collect qualitative data from 11 subjects. Most (62.2%) participants had tooth loss due to caries and findings from the final multivariable logistic regression model revealed that such loss was associated with education, residency, use of social security welfare, decayed teeth and filled teeth. Relatedly, the in-depth interview confirmed that tooth loss due to dental caries was related to (1) lack of time to visit a dentist (2) have a negative attitude toward or a phobia regarding dental treatment (3) inability to afford the high cast of dental treatment (4) lack of knowledge in regarding dental caries prevention, root canal treatment and the harmful effects of losing teeth (5) choosing to get an extraction upon having caries exposed pulp and (6) lack of oral health promotion programs provided by either the government or private sectors. The government and non-government organizations should promote oral health in an industrial estates and provide services and welfare for dental health of workers in an industrial estate appropriate to their socio-economic needs.

The impact of restorative treatment on tooth loss prevention.

PubMed

Caldas Junior, Arnaldo de França; Silveira, Renata Cimões Jovino; Marcenes, Wagner

2003-01-01

A cross-sectional study was carried out to analyze tooth loss resulting from caries in relation to the number of times the extracted tooth had been restored, the type of caries diagnosed (primary or secondary), and socioeconomic indicators of patients from the city of Recife, Brazil. Ten public health centres and ten centres associated with health insurance companies were randomly selected. The size of the sample was calculated using a standard error of 2.5%. A confidence interval of 95% and a 50% prevalence of reasons for extractions were used for calculating the sample. The minimum size of the sample for meeting these requirements was 381 patients. Patients were randomly selected from the list of adults registered at each centre. A total of 410 patients were invited to take part in the study. The response rate was 100%, but 6 patients were excluded due to incompleteness of data in the questionnaire applied. An assessment was made to obtain the number of decayed, missing or filled teeth (DMFT index) and the reasons for extraction. The results showed a highly significant (p < 0.001) relationship between the number of times the tooth indicated for extraction had been restored and the reason for extraction being caries. Furthermore, the majority of teeth extracted due to caries had been restored two or more times. A highly statistically significant association was also observed between one indicator of use of dental services (F/DMFT) and extraction due to caries (p < 0.001). The findings questioned the belief that tooth loss can be prevented in the general population by merely providing restorative treatment.

The effect of enamel proteins on erosion

NASA Astrophysics Data System (ADS)

Baumann, T.; Carvalho, T. S.; Lussi, A.

2015-10-01

Enamel proteins form a scaffold for growing hydroxyapatite crystals during enamel formation. They are then almost completely degraded during enamel maturation, resulting in a protein content of only 1% (w/v) in mature enamel. Nevertheless, this small amount of remaining proteins has important effects on the mechanical and structural properties of enamel and on the electrostatic properties of its surface. To analyze how enamel proteins affect tooth erosion, human enamel specimens were deproteinated. Surface microhardness (SMH), surface reflection intensity (SRI) and calcium release of both deproteinated and control specimens were monitored while continuously eroding them. The deproteination itself already reduced the initial SMH and SRI of the enamel significantly (p < 0.001 and p < 0.01). During the course of erosion, the progression of all three evaluated parameters differed significantly between the two groups (p < 0.001 for each). The deproteinated enamel lost its SMH and SRI faster, and released more calcium than the control group, but these differences were only significant at later stages of erosion, where not only surface softening but surface loss can be observed. We conclude that enamel proteins have a significant effect on erosion, protecting the enamel and slowing down the progression of erosion when irreversible surface loss starts to occur.

The effect of enamel proteins on erosion

PubMed Central

Baumann, T.; Carvalho, T. S.; Lussi, A.

2015-01-01

Enamel proteins form a scaffold for growing hydroxyapatite crystals during enamel formation. They are then almost completely degraded during enamel maturation, resulting in a protein content of only 1% (w/v) in mature enamel. Nevertheless, this small amount of remaining proteins has important effects on the mechanical and structural properties of enamel and on the electrostatic properties of its surface. To analyze how enamel proteins affect tooth erosion, human enamel specimens were deproteinated. Surface microhardness (SMH), surface reflection intensity (SRI) and calcium release of both deproteinated and control specimens were monitored while continuously eroding them. The deproteination itself already reduced the initial SMH and SRI of the enamel significantly (p < 0.001 and p < 0.01). During the course of erosion, the progression of all three evaluated parameters differed significantly between the two groups (p < 0.001 for each). The deproteinated enamel lost its SMH and SRI faster, and released more calcium than the control group, but these differences were only significant at later stages of erosion, where not only surface softening but surface loss can be observed. We conclude that enamel proteins have a significant effect on erosion, protecting the enamel and slowing down the progression of erosion when irreversible surface loss starts to occur. PMID:26468660

Micro-PIXE study of metal loss from dental amalgam

NASA Astrophysics Data System (ADS)

Meesat, Ridthee; Sudprasert, Wanwisa; Guibert, Edouard; Wang, Liping; Chappuis, Thibault; Whitlow, Harry J.

2017-08-01

Mercury amalgams have been a topic of controversy ever since their introduction over 150 years ago as a dental material. An interesting question is if metals are released from the amalgam into the enamel and dentine tissue. To elucidate this PIXE mapping was used to investigate metal redistribution in an extracted molar tooth with a ∼30 year old high-Cu content amalgam filling. The tooth was sectioned and polished, and elemental mapping carried out on the amalgam/enamel, bulk amalgam and the wear surface of the amalgam. As expected, the amalgam was multiphase amalgam comprising of Cu-rich and Ag-rich grains with non-uniform distribution of Hg. The amalgam/dentine interface was clearly defined with amalgam elements on one side and C and P from hydroxyapatite on the other side with evidence of only slight interface corrosion. The peaks for Cu Hg and Zn were isolated from interfering signals with concentrations in the enamel tissue, observed to be at, or below the method detection limit. The proximity in energy of the Sn L α and Ca K α , peaks and the background on the Hg M α gave signal overlap which increased the MDL for these elements. Remarkably, a course grain texture in the amalgam was observed just below the biting surface of the amalgam which might be associated with tribochemical processes from mastication. This coupled with the clear absence of the amalgam metals from tooth tissue, even in close proximity to the interface, suggests that for this sample, release of Hg occurred via erosion or dissolution in saliva.

The ability of 1.23% acidulated phosphate fluoride gel to inhibit simulated endogenous erosion in tooth roots.

PubMed

Saunders, J G C; McIntyre, J M

2005-12-01

Endogenous dental erosion is that produced by contact of gastric acids with tooth structure. It may affect exposed root cementum/dentine as well as coronal enamel, causing marked loss of mineral. The aim of this study was to determine whether 1.23 per cent acidulated phosphate fluoride gel, if applied to the surface cementum at certain intervals during an erosive acid challenge, could provide any protection against demineralization. Roots of preserved extracted human teeth were painted with a water and acid resistant varnish, leaving two windows (3x1mm) of exposed dentine. These were placed in a solution containing 0.06MHCl and 2.2mMCaHPO4, which has been shown to simulate gastric acid when it meets the tooth surface. The roots were placed in the erosive solution unprotected (controls), or subject to APF application for four minutes prior to and every 10, 30 or 120 minutes during the erosive challenge. Roots were removed at either 6 or 12 hours, washed thoroughly and cut into 120microm thick sections. Depths of demineralization were measured using an optical graticule under polarized light microscopy. A high level of protection was provided when the roots were coated with APF gel every 10 or 30 minutes. APF gel will partially inhibit endogenous erosion of roots for up to 30 minutes if applied, for example, the night before a morning reflux episode. This should be considered along with other erosion control or reduction procedures for patients suffering from the effects of endogenous erosion.

Ameloglyphics: A possible forensic tool for person identification following high temperature and acid exposure

PubMed Central

Juneja, Manjushree; Juneja, Saurabh; Rakesh, Nagaraju; Bhoomareddy Kantharaj, Yashoda Devi

2016-01-01

Introduction: Forensic odontology is a branch that is evolving over time and has opened newer avenues that may help in the identification of individuals. Tooth prints are the enamel rod end patterns on tooth surface and they are considered as a hard tissue analog to fingerprints. Teeth have the highest resistance to most environmental effects like fire, desiccation, and decomposition, and may be used as a forensic evidence. Aims and Objectives: The aim of the study was to evaluate if the tooth prints could be used for an individual's identification and reproducibility and permanency of these tooth prints after exposing the teeth to acid and various degrees of temperature. Materials and Methods: 90 tooth prints from 20 freshly extracted maxillary premolar teeth were obtained. Cellophane tape technique was used to record enamel rod end patterns on tooth surface. Ten teeth (one from each patient) were immersed in 36.46% hydrochloric acid and the tooth prints were obtained at various intervals (5 min, 10 min, and 20 min). The other 10 teeth (one from each patient) were incinerated and impression was made at various intervals (80° C, 400° C, 600° C, and 750° C). Tooth prints obtained from different teeth (total of 90 tooth prints) were analyzed using Verifinger® standard SDK version 5.0 software. Results: All the 20 original tooth prints were distinct from each other and no inter-individual or intra-individual similarity was found. The tooth prints from the same tooth after it was exposed to acid or heat were reproducible and showed high to very high similarity with the original tooth print of that particular tooth stored in the database. Conclusion: Tooth prints may be used as an effective aid in person identification even in adverse conditions such as burn and acid attack injuries. PMID:27051220

Computerized Generation and Simulation of Meshing and Contact of New Type of Novikov-Wildhaber Helical Gears

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Feng, Pin-Hao; Lagutin, Sergei A.

2000-01-01

In this report, we propose a new geometry for low-noise, increased-strength helical gears of the Novikov-Wildhaber type. Contact stresses are reduced as a result of their convex-concave gear tooth surfaces. The gear tooth surfaces are crowned in the profile direction to localize bearing contact and in the longitudinal direction to obtain a parabolic function of transmission errors. Such a function results in the reduction of noise and vibrations. Methods for the generation of the proposed gear tooth surfaces by grinding and hobbing are considered, and a tooth contact analysis (TCA) computer program to simulate meshing and contact is applied. The report also investigates the influence of misalignment on transmission errors and shift of bearing contact. Numerical examples to illustrate the developed approaches are proposed. The proposed geometry was patented by Ford/UIC (Serial Number 09-340-824, pending) on June 28, 1999.

Erosion and abrasion on dental structures undergoing at-home bleaching

PubMed Central

Demarco, Flávio Fernando; Meireles, Sônia Saeger; Sarmento, Hugo Ramalho; Dantas, Raquel Venâncio Fernandes; Botero, Tatiana; Tarquinio, Sandra Beatriz Chaves

2011-01-01

This review investigates erosion and abrasion in dental structures undergoing at- home bleaching. Dental erosion is a multifactorial condition that may be idiopathic or caused by a known acid source. Some bleaching agents have a pH lower than the critical level, which can cause changes in the enamel mineral content. Investigations have shown that at-home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant damaging effects on enamel and dentin surface properties. Most studies where erosion was observed were in vitro. Even though the treatment may cause side effects like sensitivity and gingival irritation, these usually disappear at the end of treatment. Considering the literature reviewed, we conclude that tooth bleaching agents based on hydrogen or carbamide peroxide have no clinically significant influence on enamel/dentin mineral loss caused by erosion or abrasion. Furthermore, the treatment is tolerable and safe, and any adverse effects can be easily reversed and controlled. PMID:23674914

Dental microwear textures: reconstructing diets of fossil mammals

NASA Astrophysics Data System (ADS)

DeSantis, Larisa R. G.

2016-06-01

Dietary information of fossil mammals can be revealed via the analysis of tooth morphology, tooth wear, tooth geochemistry, and the microscopic wear patterns on tooth surfaces resulting from food processing. Although dental microwear has long been used by anthropologists and paleontologists to clarify diets in a diversity of mammals, until recently these methods focused on the counting of wear features (e.g., pits and scratches) from two-dimensional surfaces (typically via scanning electron microscopes or low-magnification light microscopes). The analysis of dental microwear textures can instead reveal dietary information in a broad range of herbivorous, omnivorous, and carnivorous mammals by characterizing microscopic tooth surfaces in three-dimensions, without the counting of individual surface features. To date, dental microwear textures in ungulates, xenarthrans, marsupials, carnivorans, and primates (including humans and their ancestors) are correlated with known dietary behavior in extant taxa and reconstruct ancient diets in a diversity of prehistoric mammals. For example, tough versus hard object feeding can be characterized across disparate phylogenetic groups and can distinguish grazers, folivorous, and flesh consumers (tougher food consumers) from woody browsers, frugivores, and bone consumers (harder object feeders). This paper reviews how dental microwear textures can be useful to reconstructing diets in a broad array of living and extinct mammals, with commentary on areas of future research.

Heritability of the Number of Teeth in Middle-Aged and Older Danish Twins.

PubMed

Kurushima, Y; Silventoinen, K; Dokkedal, U; Skytthe, A; Mucci, L A; Christensen, K; Hjelmborg, J V B

2017-12-01

Tooth loss is a common health concern in older adults. We aimed to estimate the relative contributions of genetic and environmental factors to the variation in the number of teeth in middle-aged and older populations using a population-based cohort of Danish twins. The study included 5,269 Danish middle-aged or older twins who provided data on the number of teeth at baseline by structured interviews. The data were analyzed using univariate liability threshold modeling, stratified by sex and age, to estimate familial risk of tooth loss as well as estimates of heritability. In the whole cohorts, 23% of participants were edentate and 53% had retained 20 or more teeth. A statistical model including additive genetic factors and environmental factors partly shared by co-twins and partly unique to each individual twin gave the best statistical fit for the number of teeth in both age categories as well as in men and women. Overall, additive genetic factors explained 36% (95% confidence interval [CI]: 23% to 49%), common environmental factors 20% (95% CI: 9% to 31%), and unique environmental factors 44% (95% CI: 40% to 48%) of the total variation of the number of teeth. This study indicates that a substantial part of the variation in tooth loss is explained by genetic as well as environmental factors shared by co-twins. Our results implied that family background importantly affects tooth loss in both the middle-aged and the older populations. Family history is thus an important factor to take into account in dental health care.

Hippocampus-dependent spatial memory impairment due to molar tooth loss is ameliorated by an enriched environment.

PubMed

Kondo, Hiroko; Kurahashi, Minori; Mori, Daisuke; Iinuma, Mitsuo; Tamura, Yasuo; Mizutani, Kenmei; Shimpo, Kan; Sonoda, Shigeru; Azuma, Kagaku; Kubo, Kin-ya

2016-01-01

Teeth are crucial, not only for mastication, but for overall nutrition and general health, including cognitive function. Aged mice with chronic stress due to tooth loss exhibit impaired hippocampus-dependent learning and memory. Exposure to an enriched environment restores the reduced hippocampal function. Here, we explored the effects of an enriched environment on learning deficits and hippocampal morphologic changes in aged senescence-accelerated mouse strain P8 (SAMP8) mice with tooth loss. Eight-month-old male aged SAMP8 mice with molar intact or with molars removed were housed in either a standard environment or enriched environment for 3 weeks. The Morris water maze was performed for spatial memory test. The newborn cell proliferation, survival, and differentiation in the hippocampus were analyzed using 5-Bromodeoxyuridine (BrdU) immunohistochemical method. The hippocampal brain-derived neurotrophic factor (BDNF) levels were also measured. Mice with upper molars removed (molarless) exhibited a significant decline in the proliferation and survival of newborn cells in the dentate gyrus (DG) as well as in hippocampal BDNF levels. In addition, neuronal differentiation of newly generated cells was suppressed and hippocampus-dependent spatial memory was impaired. Exposure of molarless mice to an enriched environment attenuated the reductions in the hippocampal BDNF levels and neuronal differentiation, and partially improved the proliferation and survival of newborn cells, as well as the spatial memory ability. These findings indicated that an enriched environment could ameliorate the hippocampus-dependent spatial memory impairment induced by molar tooth loss. Copyright © 2015 Elsevier Ltd. All rights reserved.

Patient stratification for preventive care in dentistry.

PubMed

Giannobile, W V; Braun, T M; Caplis, A K; Doucette-Stamm, L; Duff, G W; Kornman, K S

2013-08-01

Prevention reduces tooth loss, but little evidence supports biannual preventive care for all adults. We used risk-based approaches to test tooth loss association with 1 vs. 2 annual preventive visits in high-risk (HiR) and low-risk (LoR) patients. Insurance claims for 16 years for 5,117 adults were evaluated retrospectively for tooth extraction events. Patients were classified as HiR for progressive periodontitis if they had ≥ 1 of the risk factors (RFs) smoking, diabetes, interleukin-1 genotype; or as LoR if no RFs. LoR event rates were 13.8% and 16.4% for 2 or 1 annual preventive visits (absolute risk reduction, 2.6%; 95%CI, 0.5% to 5.8%; p = .092). HiR event rates were 16.9% and 22.1% for 2 and 1 preventive visits (absolute risk reduction, 5.2%; 95%CI, 1.8% to 8.4%; p = .002). Increasing RFs increased events (p < .001). Oral health care costs were not increased by any single RF, regardless of prevention frequency (p > .41), but multiple RFs increased costs vs. no (p < .001) or 1 RF (p = .001). For LoR individuals, the association between preventive dental visits and tooth loss was not significantly different whether the frequency was once or twice annually. A personalized medicine approach combining gene biomarkers with conventional risk factors to stratify populations may be useful in resource allocation for preventive dentistry (ClinicalTrials.gov, NCT01584479).

Quasi-automatic 3D finite element model generation for individual single-rooted teeth and periodontal ligament.

PubMed

Clement, R; Schneider, J; Brambs, H-J; Wunderlich, A; Geiger, M; Sander, F G

2004-02-01

The paper demonstrates how to generate an individual 3D volume model of a human single-rooted tooth using an automatic workflow. It can be implemented into finite element simulation. In several computational steps, computed tomography data of patients are used to obtain the global coordinates of the tooth's surface. First, the large number of geometric data is processed with several self-developed algorithms for a significant reduction. The most important task is to keep geometrical information of the real tooth. The second main part includes the creation of the volume model for tooth and periodontal ligament (PDL). This is realized with a continuous free form surface of the tooth based on the remaining points. Generating such irregular objects for numerical use in biomechanical research normally requires enormous manual effort and time. The finite element mesh of the tooth, consisting of hexahedral elements, is composed of different materials: dentin, PDL and surrounding alveolar bone. It is capable of simulating tooth movement in a finite element analysis and may give valuable information for a clinical approach without the restrictions of tetrahedral elements. The mesh generator of FE software ANSYS executed the mesh process for hexahedral elements successfully.

Concept and clinical application of the resin-coating technique for indirect restorations.

PubMed

Nikaido, Toru; Tagami, Junji; Yatani, Hirofumi; Ohkubo, Chikahiro; Nihei, Tomotaro; Koizumi, Hiroyasu; Maseki, Toshio; Nishiyama, Yuichiro; Takigawa, Tomoyoshi; Tsubota, Yuji

2018-03-30

The resin-coating technique is one of the successful bonding techniques used for the indirect restorations. The dentin surfaces exposed after cavity preparation are coated with a thin film of a coating material or a dentin bonding system combined with a flowable composite resin. Resin coating can minimize pulp irritation and improve the bond strength between a resin cement and tooth structures. The technique can also be applied to endodontically treated teeth, resulting in prevention of coronal leakage of the restorations. Application of a resin coating to root surface provides the additional benefit of preventing root caries in elderly patients. Therefore, the coating materials have the potential to reinforce sound tooth ("Super Tooth" formation), leading to preservation of maximum tooth structures.

Sleep bruxism: challenges and restorative solutions

PubMed Central

Mengatto, Cristiane Machado; Coelho-de-Souza, Fábio Herrmann; de Souza Junior, Oswaldo Baptista

2016-01-01

Bruxism is a parafunctional activity related to clenching or grinding the teeth and tooth wear can be a consequence of sleep bruxism (SB). Management of severe tooth wear due to SB is a challenging situation because of the common reduced amount of remaining dental structure and loss of vertical dimension of occlusion. Rationale for the planning of oral rehabilitation of patients with SB presenting severe tooth wear should rely on evidence-based approaches; however, few studies have discussed properties of dental materials for SB rehabilitation and how to cosmetically manage severe tooth wear. This review aimed to provide an overview into bruxism cosmetic rehabilitation and how this can be implemented with good outcomes for the patient. PMID:27217798

Tooth wear in three ethnic groups in Sabah (northern Borneo).

PubMed

Milosevic, A; Lo, M S

1996-12-01

The prevalence and associated aetiologies of tooth wear were investigated in three ethnic groups in Sabah (Northern Borneo) using the Tooth Wear Index (TWI). The number of surfaces with enamel wear only, dentine exposed for less than a third or dentine exposed for more than a third were categorised into the TW minimal, moderate or severe respectively. A structured questionnaire was used to elicit medical/dental history, oral hygiene practices, satisfaction with body image, diet and other personal habits/details. The sample comprised of a self selected sample of 148 dental hospital attenders; 47 (32 per cent) each of ethnic Chinese and Malay and 54 (36 per cent) of ethnic Kadazan, matched for age and with a similar number of scoreable teeth per subject. Dentine exposure within the total sample was a common finding (95 per cent TW with moderate, 41 per cent TW severe). The Kadazan group had significantly (P < 0.05) more surfaces with severe tooth wear than the Chinese or Malay. Tobacco chewing was positively associated (rho = +0.4, P < 0.05) with both moderate and severe tooth wear, as was the habit of crushing/eating bones. Neither carbonated beverages or fresh fruit intake were associated with tooth wear, but their frequency of consumption was low. The buccal and occlusal surfaces of the posterior teeth were the most severely worn. Generally, wear was greater in the upper anterior sextant compared to the lower anterior sextant, with the exception of the lower incisal edges in the Kadazan group. Tooth wear into dentine was a common occurrence, especially among the Kadazan subjects and least among the Chinese subjects. The aetiological factors associated with this tooth wear are different to those encountered in Western cultures.

Shear bond strengths of tooth coating materials including the experimental materials contained various amounts of multi-ion releasing fillers and their effects for preventing dentin demineralization.

PubMed

Arita, Shoko; Suzuki, Masaya; Kazama-Koide, Miku; Shinkai, Koichi

2017-10-01

We examined shear bond strengths (SBSs) of various tooth-coating-materials including the experimental materials to dentin and demineralization resistance of a fractured adhesive surface after the SBS testing. Three resin-type tooth-coating-materials (BC, PRG Barrier Coat; HC, Hybrid Coat II; and SF, Shield force plus) and two glass-ionomer-type tooth-coating-materials (CV, Clinpro XT Varnish; and FJ, Fuji VII) were selected. The experimental PRG Barrier Coat containing 0, 17, and 33 wt% S-PRG filler (BC0, BC17, and BC33, respectively) were developed. Each tooth-coating-material was applied to flattened dentin surfaces of extracted human teeth for SBS testing. After storing in water for 32 days with 4000 thermal cycling, the specimens were subjected to the SBS test. Specimens after SBS testing were subjected to a pH cycling test, and then, demineralization depths were measured using a polarized-light microscope. ANOVA and Tukey's HSD test were used for statistical analysis. The SBS value of FJ and CV was significantly lower than those of other materials except for BC (p < 0.01). The lesion depth of FJ was significantly shallower than those of other materials (p < 0.01); that of CV was significantly shallower than those of BC, HC, SF, and the control; and those of BC0 and BC17 were significantly shallower than that of the control (p < 0.05). The resin-type tooth-coating-materials demonstrated significantly higher SBS for dentin than the glass-ionomer-type tooth-coating-materials; however, they were inferior to the glass ionomer-type tooth-coating-materials in regards to the acid resistance of the fractured adhesion surface.

In Vitro Investigation of Wear of CAD/CAM Polymeric Materials Against Primary Teeth.

PubMed

Choi, Jae-Won; Song, Eun-Ju; Shin, Jong-Hyun; Jeong, Tae-Sung; Huh, Jung-Bo

2017-12-09

The aim of the study was to evaluate the effects of polymeric computer-aided design/computer-aided manufacturing CAD/CAM materials on antagonistic primary tooth wear. Five CAD/CAM polymeric materials were examined: Vipi Block Monocolor (VBM), Yamahachi polymethylmethacrylate (PMMA) (YAP), Mazic Duro (MZD), Vita Enamic (ENA), and Pekkton (PEK). All of the specimens were tested in a thermomechanical loading machine with the primary canine as the antagonist (50 N, 1.2 × 10⁵ cycles, 1.7 Hz, 5/55 °C). The wear losses of the antagonist tooth and the restorative materials were calculated using reverse modelling software and an electronic scale. VBM and ENA showed significantly higher antagonist tooth wear than PEK ( p < 0.05), but there was no significant difference observed among VBM, YAP, MZD, and ENA ( p > 0.05). PEK showed the largest value in both material volumetric and weight losses. In terms of material volumetric losses, there was no significant difference between all of the groups ( p > 0.05). In terms of material weight losses, PEK was significantly larger than ENA ( p < 0.05), but there was no significant difference between VBM, YAP, MZD, and ENA ( p > 0.05). Volumetric and weight losses of materials showed similar wear behaviour. However, the wear patterns of antagonists and materials were different, especially in PEK.

In Vitro Investigation of Wear of CAD/CAM Polymeric Materials Against Primary Teeth

PubMed Central

Song, Eun-Ju; Shin, Jong-Hyun; Jeong, Tae-Sung; Huh, Jung-Bo

2017-01-01

The aim of the study was to evaluate the effects of polymeric computer-aided design/computer-aided manufacturing CAD/CAM materials on antagonistic primary tooth wear. Five CAD/CAM polymeric materials were examined: Vipi Block Monocolor (VBM), Yamahachi polymethylmethacrylate (PMMA) (YAP), Mazic Duro (MZD), Vita Enamic (ENA), and Pekkton (PEK). All of the specimens were tested in a thermomechanical loading machine with the primary canine as the antagonist (50 N, 1.2 × 105 cycles, 1.7 Hz, 5/55 °C). The wear losses of the antagonist tooth and the restorative materials were calculated using reverse modelling software and an electronic scale. VBM and ENA showed significantly higher antagonist tooth wear than PEK (p < 0.05), but there was no significant difference observed among VBM, YAP, MZD, and ENA (p > 0.05). PEK showed the largest value in both material volumetric and weight losses. In terms of material volumetric losses, there was no significant difference between all of the groups (p > 0.05). In terms of material weight losses, PEK was significantly larger than ENA (p < 0.05), but there was no significant difference between VBM, YAP, MZD, and ENA (p > 0.05). Volumetric and weight losses of materials showed similar wear behaviour. However, the wear patterns of antagonists and materials were different, especially in PEK. PMID:29232849

Restorative Management of Intrinsic and Extrinsic Dental Erosion.

PubMed

Al-Salehi, Samira Kathryn

2014-12-01

The restorative management of tooth surface loss is highlighted through the presentation of two advanced cases of dental erosion. On presentation, the causes of the dental erosion in both patients had been previously diagnosed and stopped. The first patient was a 67 year old with intrinsic erosion and an element of attrition where a multidisciplinary approach was used. The other, a 17 year old patient with extrinsic erosion managed via adhesive restorations. Adhesive techniques are a relatively simple, effective and conservative method for the treatment of dental erosion. The two treatment modalities (conventional versus contemporary) are compared and discussed.

Assessment and management of dental erosion.

PubMed

Wang, Xiaojie; Lussi, Adrian

2010-07-01

Studies have shown a growing trend toward increasing prevalence of dental erosion, associated with the declining prevalence of caries disease in industrialized countries. Erosion is an irreversible chemical process that results in tooth substance loss and leaves teeth susceptible to damage as a result of wear over the course of an individual's lifetime. Therefore, early diagnosis and adequate prevention are essential to minimize the risk of tooth erosion. Clinical appearance is the most important sign to be used to diagnose erosion. The Basic Erosive Wear Examination (BEWE) is a simple method to fulfill this task. The determination of a variety of risk and protective factors (patient-dependent and nutrition-dependent factors) as well as their interplay are necessary to initiate preventive measures tailored to the individual. When tooth loss caused by erosive wear reaches a certain level, oral rehabilitation becomes necessary. Copyright 2010 Elsevier Inc. All rights reserved.

Topology of modified helical gears and Tooth Contact Analysis (TCA) program

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Zhang, Jiao

1989-01-01

The contents of this report covers: (1) development of optimal geometries for crowned helical gears; (2) a method for their generation; (3) tooth contact analysis (TCA) computer programs for the analysis of meshing and bearing contact of the crowned helical gears; and (4) modelling and simulation of gear shaft deflection. The developed method for synthesis was used to determine the optimal geometry for a crowned helical pinion surface and was directed to localize the bearing contact and guarantee favorable shape and a low level of transmission errors. Two new methods for generation of the crowned helical pinion surface are proposed. One is based on the application of a tool with a surface of revolution that slightly deviates from a regular cone surface. The tool can be used as a grinding wheel or as a shaver. The other is based on a crowning pinion tooth surface with predesigned transmission errors. The pinion tooth surface can be generated by a computer-controlled automatic grinding machine. The TCA program simulates the meshing and bearing contact of the misaligned gears. The transmission errors are also determined. The gear shaft deformation was modelled and investigated. It was found that the deflection of gear shafts has the same effect as gear misalignment.

Determining Tooth Occlusal Surface Relief Indicator by Means of Automated 3d Shape Analysis

NASA Astrophysics Data System (ADS)

Gaboutchian, A. V.; Knyaz, V. A.

2017-05-01

Determining occlusal surface relief indicator plays an important role in odontometric tooth shape analysis. An analysis of the parameters of surface relief indicators provides valuable information about closure of dental arches (occlusion) and changes in structure of teeth in lifetime. Such data is relevant for dentistry or anthropology applications. Descriptive techniques commonly used for surface relief evaluation have limited precision which, as a result, does not provide for reliability of conclusions about structure and functioning of teeth. Parametric techniques developed for such applications need special facilities and are time-consuming which limits their spread and ease to access. Nevertheless the use of 3D models, obtained by photogrammetric techniques, allows attaining required measurements accuracy and has a potential for process automation. We introduce new approaches for determining tooth occlusal surface relief indicator and provide data on efficiency in use of different indicators in natural attrition evaluation.

To Analyse the Erosive Potential of Commercially Available Drinks on Dental Enamel and Various Tooth Coloured Restorative Materials - An In-vitro Study.

PubMed

Karda, Babita; Jindal, Ritu; Mahajan, Sandeep; Sandhu, Sanam; Sharma, Sunila; Kaur, Rajwinder

2016-05-01

With the enormous change in life style pattern of a common man through the past few decades, there has been proportional variation in the amount and frequency of consumption of drinks. An increased consumption of these drinks will concurrently increase enamel surface roughness by demineralization, resulting in hypersensitivity and elevated caries risk. The present study was designed to evaluate the erosive potential of commercially available drinks on tooth enamel and various tooth coloured restorative materials. Extracted human teeth were taken and divided into four groups i.e. tooth enamel, glass ionomer cement, composite and compomer. Four commercially available drinks were chosen these were Coca -Cola, Nimbooz, Frooti and Yakult. The pH of each drink was measured. Each group was immersed in various experimental drinks for a period of 14 days. The erosive potential of each drink was measured by calculating the change in average surface roughness of these groups after the immersion protocol in various drinks. The data analysis was done by One Way Anova, Post-Hoc Bonferroni, and paired t -test. Group II-GIC showed highest values for mean of change in average surface roughness and the values were statistically significant (p<0.001) with tooth enamel, composite and compomer (p=0.002). Coca-cola showed the highest erosive potential and Yakult showed the lowest, there was no statistical significant difference between the results shown by Yakult and Frooti. Characteristics which may promote erosion of enamel and tooth coloured restorative materials were surface texture of the material and pH of the drinks.

Performance of fast-setting impression materials in the reproduction of subgingival tooth surfaces without soft tissue retraction.

PubMed

Rudolph, Heike; Röhl, Andreas; Walter, Michael H; Luthardt, Ralph G; Quaas, Sebastian

2014-01-01

Fast-setting impression materials may be prone to inaccuracies due to accidental divergence from the recommended mixing protocol. This prospective randomized clinical trial aimed to assess three-dimensional (3D) deviations in the reproduction of subgingival tooth surfaces and to determine the effect of either following or purposely diverging from the recommended mixing procedure for a fast-setting addition-curing silicone (AS) and fast-setting polyether (PE). After three impressions each were taken from 96 participants, sawcut gypsum casts were fabricated with a standardized procedure and then optically digitized. Data were assessed with a computer-aided 3D analysis. For AS impressions, multivariate analysis of variance revealed a significant influence of the individual tooth and the degree to which the recommended mixing protocol was violated. For PE impressions, the ambient air temperature and individual tooth showed significant effects, while divergence from the recommended mixing protocol was not of significance. The fast-setting PE material was not affected by changes in the recommended mixing protocol. For the two fast-setting materials examined, no divergences from the recommended mixing protocol of less than 2 minutes led to failures in the reproduction of the subgingival tooth surfaces.

Autotransplantation of a maxillary third molar to replace a maxillary premolar with vertical root fracture.

PubMed

Tsurumachi, T; Kakehashi, Y

2007-12-01

To report the successful autotransplantation of a fully developed third molar that required nonsurgical and surgical interventions for tooth adaptation. This case report describes the autotransplantation of a third molar with complete root development after the loss of a fractured premolar in a 47-year-old male. To allow better adaptation of the donor tooth, the buccal roots of the third molar were removed using a diamond bur and the canal entrances were filled. Recall examination 6 years after completion of root-canal treatment showed normal periodontal healing with absence of infection, ankylosis or progressive resorption. The transplantation of a third molar is seen as a promising method to replace a lost permanent tooth, and to restore aesthetics and function. *Autotransplantation is a viable option for the treatment of a missing tooth or for replacement of traumatized tooth when there is a donor tooth available. *Fully developed third molars are potentially reliable candidates in the absence of other suitable donor teeth.

[Effect of the vacuum-formed retainer on preventing the proximal contact loss between implant supported crown and adjacent natural teeth].

PubMed

Zeng, B J; Guo, Y; Yu, R Y

2018-06-18

To evaluate the effect of the vacuum-formed retainer on preventing the proximal contact loss between the implant supported crown and its adjacent natural teeth. Forty-six posterior implant crowns in the mandible including 92 interproximal contacts in 46 patients (19 men, 27 women) aged from 25 to 66 years were included. The participants in experimental group (22 cases) were vacuum-formed retainers at night, while participants in control group (24 cases) only received routine examination. The two groups were not different in age, gender, the time interval of the tooth loss and tooth position at baseline. Mesial and distal proximal contact tightness was measured using the orthodontic dynamometer and metallic articulating film immediately after crown delivery, and 1-month, 3-month, 6-month, and 1-year follow-up respectively. The articulating film was inserted interdentally from the occlusal direction, and then it was slowly removed in the buccallingual direction by the dynamometer. Increasing the number of films (N) piece by piece until the frictional force (F) was great than 0, and the number of films (N) was recorded. At each follow-up, proximal contact between implant crown and its adjacent teeth was considered to be loss if the number of films (N) used at immediate crown delivery passed without frictional force (F=0). Besides, the periodontal conditions [scored according to the probing depth (PD), bleeding index (BI), mobility (M)] and complaint of food impaction were recorded. The mesial and distal proximal contact loss rates were compared between the two groups at different times. Chi-square test or Fisher's exact test was used for statistical analysis. The proximal contact loss rate on the mesial surface of the implant supported crown continuously increased over the follow-up periods. At the end of the 1-, 3-, and 6-month follow ups, 18.2%, 22.7% and 27.3% were identified for the contact loss rates on the mesial surface of the implant supported crown in the experimental group, respectively. Meanwhile in control group, the rates were 20.8%, 37.5% and 45.8%. No significant differences were observed at the end of the 1-, 3-, and 6-month follow ups(1-month: χ 2 =0.000, P=1.000; 3-month: χ 2 =1.183, P=0.277; 6-month: χ 2 =1.697, P=0.193). The proximal contact loss rate on the mesial surface in control group (62.5%) was significantly higher than that in the experimental group (31.8%, χ 2 =4.330, P=0.037) at the end of the 1-year follow-up. However, no statistical difference was found on the distal surfaces between the two groups during the whole follow-up periods. The first open contact was noted 1 month after crown insertion. By wearing vacuum-formed retainer for one year, the incidence of open contacts between the posterior implant prostheses and mesial adjacent teeth in the mandible has been reduced.

Prospective Study of Oral Health and Risk of Primary Open-Angle Glaucoma in Men: Data from the Health Professionals Follow-up Study.

PubMed

Pasquale, Louis R; Hyman, Leslie; Wiggs, Janey L; Rosner, Bernard A; Joshipura, Kaumudi; McEvoy, Mark; McPherson, Zachary E; Danias, John; Kang, Jae H

2016-11-01

Tooth loss or periodontal disease is associated with systemic endothelial dysfunction, which has been implicated in primary open-angle glaucoma (POAG). The relationship between oral health and POAG has received limited attention. Thus, we evaluated the association between oral health history and risk of POAG and POAG subtypes. Prospective cohort study. Health Professionals Follow-up Study participants (40 536 men) followed biennially from 1986 to 2012. At each 2-year risk period, eligible participants were aged 40+ years, were free of POAG, and reported eye examinations. By using validated questions, we updated participants' status on number of natural teeth, teeth lost, periodontal disease with bone loss, and root canal treatments. During follow-up, 485 incident cases of POAG were confirmed with medical records and classified into subtypes defined by intraocular pressure (IOP; ≥ or <22 mmHg) or visual field (VF) loss pattern at diagnosis (peripheral loss only or early paracentral loss). Multivariable relative risks (MVRRs) and 95% confidence intervals (CIs) were estimated. Number of natural teeth, periodontal disease, and root canal treatment were not associated with POAG. However, compared with no report of tooth loss, a report of losing teeth within the past 2 years was associated with a 1.45-fold increased risk of POAG (95% CI, 1.06-1.97); in particular, a report within the past 2 years of both losing teeth and having a prevalent diagnosis of periodontal disease was associated with a 1.85-fold increased risk of POAG (95% CI, 1.07-3.18). The associations with recent tooth loss were not significantly different for the POAG subtypes (P for heterogeneity ≥0.36), although associations were strongest in relation to the POAG subtypes with IOP <22 mmHg (MVRR, 1.93; 95% CI, 1.09-3.43) and early paracentral VF loss (MVRR, 2.27; 95% CI, 1.32-3.88). Although the number of natural teeth was not associated with risk of POAG, recent tooth loss was associated with an increased risk of POAG. Because these findings may be due to chance, they need confirmation in larger studies. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Application of the specular and diffuse reflection analysis for in vitro diagnostics of dental erosion: correlation with enamel softening, roughness, and calcium release

PubMed Central

Rakhmatullina, Ekaterina; Bossen, Anke; Höschele, Christoph; Wang, Xiaojie; Beyeler, Barbara; Meier, Christoph; Lussi, Adrian

2011-01-01

We present assembly and application of an optical reflectometer for the analysis of dental erosion. The erosive procedure involved acid-induced softening and initial substance loss phases, which are considered to be difficult for visual diagnosis in a clinic. Change of the specular reflection signal showed the highest sensitivity for the detection of the early softening phase of erosion among tested methods. The exponential decrease of the specular reflection intensity with erosive duration was compared to the increase of enamel roughness. Surface roughness was measured by optical analysis, and the observed tendency was correlated with scanning electron microscopy images of eroded enamel. A high correlation between specular reflection intensity and measurement of enamel softening (r2 ≥ −0.86) as well as calcium release (r2 ≥ −0.86) was found during erosion progression. Measurement of diffuse reflection revealed higher tooth-to-tooth deviation in contrast to the analysis of specular reflection intensity and lower correlation with other applied methods (r2 = 0.42–0.48). The proposed optical method allows simple and fast surface analysis and could be used for further optimization and construction of the first noncontact and cost-effective diagnostic tool for early erosion assessment in vivo. PMID:22029364

Application of the specular and diffuse reflection analysis for in vitro diagnostics of dental erosion: correlation with enamel softening, roughness, and calcium release

NASA Astrophysics Data System (ADS)

Rakhmatullina, Ekaterina; Bossen, Anke; Höschele, Christoph; Wang, Xiaojie; Beyeler, Barbara; Meier, Christoph; Lussi, Adrian

2011-10-01

We present assembly and application of an optical reflectometer for the analysis of dental erosion. The erosive procedure involved acid-induced softening and initial substance loss phases, which are considered to be difficult for visual diagnosis in a clinic. Change of the specular reflection signal showed the highest sensitivity for the detection of the early softening phase of erosion among tested methods. The exponential decrease of the specular reflection intensity with erosive duration was compared to the increase of enamel roughness. Surface roughness was measured by optical analysis, and the observed tendency was correlated with scanning electron microscopy images of eroded enamel. A high correlation between specular reflection intensity and measurement of enamel softening (r2 >= -0.86) as well as calcium release (r2 >= -0.86) was found during erosion progression. Measurement of diffuse reflection revealed higher tooth-to-tooth deviation in contrast to the analysis of specular reflection intensity and lower correlation with other applied methods (r2 = 0.42-0.48). The proposed optical method allows simple and fast surface analysis and could be used for further optimization and construction of the first noncontact and cost-effective diagnostic tool for early erosion assessment in vivo.

The role of oral hygiene: does toothbrushing harm?

PubMed

Wiegand, Annette; Schlueter, Nadine

2014-01-01

Although toothbrushing is considered a prerequisite for maintaining good oral health, it also has the potential to have an impact on tooth wear, particularly with regard to dental erosion. Experimental studies have demonstrated that tooth abrasion can be influenced by a number of factors, including not only the physical properties of the toothpaste and toothbrush used but also patient-related factors such as toothbrushing frequency and force of brushing. While abrasion resulting from routine oral hygiene can be considered as physiological wear over time, intensive brushing might further harm eroded surfaces by removing the demineralised enamel surface layer. The effects of brushing on eroded dentine are not fully elucidated, particular under in vivo conditions. However, there are indications that brushing after an acid impact causes less additional hard tissue loss in dentine than in enamel. Toothbrushing frequency and force as well as toothbrush hardness were shown to act as co-factors in the multifactorial aetiology of non-cervical carious lesions. In vitro studies showed that toothbrushing abrasion is primarily related to the abrasivity of the toothpaste, while the toothbrush acts as a carrier, only modifying the effects of the toothpaste. The benefits of normal oral hygiene procedure exceed possible side effects by far, but excessive toothbrushing - especially of eroded teeth - might cause some harmful effects. © 2014 S. Karger AG, Basel.

Bluetooth technology for prevention of dental caries.

PubMed

Kolahi, Jafar; Fazilati, Mohamad

2009-12-01

Caries is caused when the pH at the tooth surface drops below 5.5. A miniaturized and autonomous pH monitoring nodes can be attached to the tooth surface, like a tooth jewel. This intelligent sensor includes three components: (a) digital micro pH meter, (b) power supply, (c) wireless communicating device. The micro pH meter facilitates long term tooth surface pH monitoring and providing real time feedback to the patients and dental experts. Power supply of this system will be microfabricated biocatalytic fuel cell (enzymatic micro-battery) using organic compounds (e.g. formate or glucose) as the fuel to generate electricity. When micro pH meter detects the pH lower than 5.5, wireless Bluetooth device sends a caution (e.g. "you are at risk of dental caries") to external monitoring equipment such as mobile phone or a hands-free heads. After reception of the caution, subjects should use routine brushing and flossing procedure or use a medicated chewing gum (e.g. chlorhexidine containing chewing gum) or rinse with a mouthwash.

Influence of surgical and prosthetic techniques on marginal bone loss around titanium implants. Part I: immediate loading in fresh extraction sockets.

PubMed

Berberi, Antoine N; Tehini, Georges E; Noujeim, Ziad F; Khairallah, Alexandre A; Abousehlib, Moustafa N; Salameh, Ziad A

2014-10-01

Delayed placement of implant abutments has been associated with peri-implant marginal bone loss; however, long-term results obtained by modifying surgical and prosthetic techniques after implant placement are still lacking. This study aimed to evaluate the marginal bone loss around titanium implants placed in fresh extraction sockets using two loading protocols after a 5-year follow-up period. A total of 36 patients received 40 titanium implants (Astra Tech) intended for single-tooth replacement. Implants were immediately placed into fresh extraction sockets using either a one-stage (immediate loading by placing an interim prosthesis into functional occlusion) or a two-stage prosthetic loading protocol (insertion of abutments after 8 weeks of healing time). Marginal bone levels relative to the implant reference point were evaluated at four time intervals using intraoral radiographs: at time of implant placement, and 1, 3, and 5 years after implant placement. Measurements were obtained from mesial and distal surfaces of each implant (α = 0.05). One-stage immediate implant placement into fresh extraction sockets resulted in a significant reduction in marginal bone loss (p < 0.002) compared to the traditional two-stage technique. Whereas mesial surfaces remained stable for the 5-year observation period, significant marginal bone loss was observed on distal surfaces of implants after cementation of interim prostheses (p < 0.007) and after 12 months (p < 0.034). Within the limitations of this study, immediate loading of implants placed into fresh extraction sockets reduced marginal bone loss and did not compromise the success rate of the restorations. © 2014 by the American College of Prosthodontists.

Wear of human enamel: a quantitative in vitro assessment.

PubMed

Kaidonis, J A; Richards, L C; Townsend, G C; Tansley, G D

1998-12-01

Many factors influence the extent and rate at which enamel wears. Clinical studies in humans are limited by difficulties in the accurate quantification of intra-oral wear and by a lack of control over the oral environment. The purpose of this study was to determine the wear characteristics of human dental enamel under controlled experimental conditions. An electro-mechanical tooth wear machine, in which opposing enamel surfaces of sectioned, extracted teeth were worn under various conditions, was used to simulate tooth grinding or bruxism. Enamel surface wear was quantified by weight to an accuracy of 0.1 mg, with water uptake and loss controlled. The variables considered included the structure and hardness of enamel, facet area, duration of tooth contact, relative speed of opposing surfaces, temperature, load, pH, and the nature of the lubricant. Enamel wear under non-lubricated conditions increased with increasing load over the range of 1.7 to 16.2 kg. The addition of a liquid lubricant (pH = 7) reduced enamel wear up to 6.7 kg, but when the load increased above this threshold, the rate of wear increased dramatically. With the viscosity of the lubricant constant and pH = 3, the rate of wear was further reduced to less than 10% of the non-lubricated rate at 9.95 kg, after which the rate again increased substantially. Under more extreme conditions (pH = 1.2, simulating gastric acids), the wear was excessive under all experimental loads. When saliva was used as a lubricant, the amount of wear was relatively low at 9.95 kg, but rapid wear occurred at 14.2 kg and above. These results indicate that under non-lubricated conditions, enamel wear remains low at high loads due to the dry-lubricating capabilities of fine enamel powder. Under lubricated conditions, low loads with an acidic lubricant lead to little enamel wear, whereas very low pH results in a high rate of wear under all loads.

Porosity Formation and Microleakage of Composite Resins Using the Snowplow Technique

DTIC Science & Technology

2012-05-04

on a proximal surface of mounted 3rd molar tooth samples. A bonding agent (Optibond FL, Kerr) was placed and light cured (Bluephase 16i, Ivoclar...Page Figure 1 Tooth preparation........................................................................ 20 Figure 2 Skyscan...al., 2010). Combined with dental adhesives, composites provide esthetically conservative restorations due to their ability to bond to tooth structure

Generation of helical gears with new surfaces topology by application of CNC machines

NASA Technical Reports Server (NTRS)

Litvin, F. L.; Chen, N. X.; Hsiao, C. L.; Handschuh, Robert F.

1993-01-01

Analysis of helical involute gears by tooth contact analysis shows that such gears are very sensitive to angular misalignment that leads to edge contact and the potential for high vibration. A new topology of tooth surfaces of helical gears that enables a favorable bearing contact and a reduced level of vibration is described. Methods for grinding of the helical gears with the new topology are proposed. A TCA (tooth contact analysis) program for simulation of meshing and contact of helical gears with the new topology has been developed. Numerical examples that illustrate the proposed ideas are discussed.

Generation of helical gears with new surfaces, topology by application of CNC machines

NASA Technical Reports Server (NTRS)

Litvin, F. L.; Chen, N. X.; Hsiao, C. L.; Handschuh, R. F.

1993-01-01

Analysis of helical involute gears by tooth contact analysis shows that such gears are very sensitive to angular misalignment that leads to edge contact and the potential for high vibration. A new topology of tooth surfaces of helical gears that enables a favorable bearing contact and a reduced level of vibration is described. Methods for grinding of the helical gears with the new topology are proposed. A TCA (tooth contact analysis) program for simulation of meshing and contact of helical gears with the new topology has been developed. Numerical examples that illustrate the proposed ideas are discussed.

Computerized Design and Analysis of Face-Milled, Uniform Tooth Height Spiral Bevel Gear Drives

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Wang, Anngwo; Handschuh, R. F.

1996-01-01

Face-milled spiral bevel gears with uniform tooth height are considered. An approach is proposed for the design of low noise and localized bearing contact of such gears. The approach is based on the mismatch of contacting surfaces and permits two types of bearing contact either directed longitudinally or across the surface to be obtained. A Tooth Contact Analysis (TCA) computer program was developed. This analysis was used to determine the influence of misalignment on meshing and contact of the spiral bevel gears. A numerical example that illustrates the developed theory is provided.

Anxiety, depression, and oral health among US pregnant women: 2010 Behavioral Risk Factor Surveillance System.

PubMed

Silveira, Marushka L; Whitcomb, Brian W; Pekow, Penelope; Carbone, Elena T; Chasan-Taber, Lisa

2016-01-01

Maternal periodontal disease is associated with adverse perinatal outcomes. Anxiety and depression adversely impact oral health in nonpregnant women; however, this association has not been evaluated during pregnancy, a time characterized by higher rates of anxiety and depression. Therefore, we examined the association between these factors and oral disease and oral healthcare utilization among 402 pregnant respondents to the 2010 Behavioral Risk Factor Surveillance System. Self-reported lifetime diagnoses of anxiety, depression, and current depression were assessed. Oral health outcomes included self-reported tooth loss and dental visits in the past year. One-fifth (21.2 percent) of respondents reported a tooth loss and 32.5 percent reported nonuse of oral health services. The prevalence of lifetime diagnosed anxiety and depression was 13.6 percent and 11.3 percent, respectively, whereas 10.6 percent reported current depression. After adjusting for risk factors, pregnant women with diagnosed anxiety had increased odds of one or more tooth loss [odds ratio (OR) = 3.30; 95 percent confidence interval (CI): 1.01-10.77] compared with those without the disorder. Similarly, after adjusting for socioeconomic factors, women with anxiety had increased odds of nonuse of oral health services (OR = 2.67; 95 percent CI: 1.03-6.90); however, this was no longer significant after adjusting for health behaviors and body mass index. We observed no significant association with depression. In this population-based sample, we found a two- to threefold increased odds of tooth loss and nonuse of oral health services among pregnant women with a lifetime diagnosis of anxiety. To our knowledge, this is the first study to examine these associations among pregnant women. © 2015 American Association of Public Health Dentistry.

Tooth loss due to periodontal abscess: a retrospective study.

PubMed

McLeod, D E; Lainson, P A; Spivey, J D

1997-10-01

This retrospective study focused on the frequency of tooth loss due to periodontal abscess among 42 patients who were treated by a single clinician over a 5- to 29-year period. A total of 114 patients were selected from the active periodontal recall schedule of a single periodontist at The University of Iowa College of Dentistry. The criteria for inclusion in the study included having a history of moderate to advanced periodontitis, being on 3 to 6 month recall periodontal maintenance care, and completion of active periodontal therapy prior to October 1987. Other parameters evaluated were age; gender; number of teeth present and missing at the initial, reevaluation, and last periodontal recall visit; initial periodontal prognosis; furcation involvement; non-surgical and surgical periodontal therapy; and reasons for tooth loss. Patients were grouped according to the number of teeth lost following active periodontal treatment into well-maintained (0 to 3), downhill (4 to 9), and extreme downhill (10 to 23) groups. Forty-two of the 114 patients were identified as having one or more periodontal abscesses. A total of 109 teeth were affected by periodontal abscess of which 49 (45%) teeth were lost and 60 (55%) were successfully maintained over an average of 12.5 years (5 to 29 years). More furcated teeth were lost than nonfurcated teeth and teeth given a hopeless prognosis were lost more consistently than those given a questionable prognosis in all groups. The frequency of periodontal abscess and tooth loss per patient was greater in the downhill and extreme downhill response groups than the well-maintained group. This suggests that teeth with a history of periodontal abscess can be treated and maintained for several years.

Tooth loss associated with physical and cognitive decline in older adults.

PubMed

Tsakos, Georgios; Watt, Richard G; Rouxel, Patrick L; de Oliveira, Cesar; Demakakos, Panayotes

2015-01-01

To examine the effect of total tooth loss (edentulousness) on decline in physical and cognitive functioning over 10 years in older adults in England. Secondary data analysis. English Longitudinal Study of Ageing, a national prospective cohort study of community-dwelling people aged 50 and older. Individuals aged 60 and older (N = 3,166). Cognitive function (memory) was measured using a 10-word recall test. Physical function was assessed using gait speed (m/s). Generalized estimating equations were used to model associations between baseline edentulousness and six repeated measurements of gait speed and memory from 2002-03 to 2012-13. Models were sequentially adjusted for time, demographic characteristics, socioeconomic status, comorbidities, health behaviors, depressive symptoms, and anthropometric measurements and mutually adjusted for gait speed or memory. Edentulous participants recalled 0.88 fewer words and were 0.09 m/s slower than dentate participants after adjusting for time and demographics. Only the latter association remained significant after full adjustment, with edentulous participants being 0.02 m/s slower than dentate participants. In age-stratified analyses, baseline edentulousness was associated with both outcomes in fully adjusted models in participants aged 60 to 74 but not in those aged 75 and older. Supplementary analysis indicated significant associations between baseline edentulousness and 4-year change in gait speed and memory in participants aged 60 to 74; the former was fully explained in the fully adjusted model and the latter after adjusting for socioeconomic status. Total tooth loss was independently associated with physical and cognitive decline in older adults in England. Tooth loss is a potential early marker of decline in older age. © 2014, Copyright the Authors Journal compilation © 2014, The American Geriatrics Society.

Is the value of oral health related to culture and environment, or function and aesthetics?

PubMed

Nassani, M Z; Kay, E J; Al-Nahhal, T I; Okşayan, R; Usumez, A; Mohammadi, T M

2015-12-01

To examine the disutility of tooth loss. It compared how people value their teeth in two countries which are culturally similar in order to explore the effect of culture on self-perceptions of oral health. Cross sectional study. Participants were recruited from subjects attending two hospitals in Turkey and in Iran. Nineteen descriptions of mouths with varying degrees and types of tooth loss were presented to the participants. They were shown mouth models of partially edentate dentitions and the teeth missing were explained in relation to the participants own mouth. The participants were specifically asked to consider the role their teeth played in function (chewing), communication (speech) and aesthetics (looks) along with "all the other things that make your mouth important". The participants were asked to indicate on a visual analogue scale how they would value the health of their mouth if they lost the tooth/teeth described and the resultant space was left unrestored. Overall 152 subjects participated, 78 in Turkey and 74 in Iran with 83 being female and 69 male. Their mean age was 29.5 years (SD 9.3), 62.5% had experienced tooth loss and 37.5% had complete (or completely restored) dentitions. Although there were no differences between the two countries in the degree of utility people attached to anterior teeth, Turkish participants attached significantly more disutility than Iranians to the loss of premolar and molar teeth (p < 0.003). Country of origin had an influence on the value placed on certain parts of the dentition and this effect is independent of the number of missing teeth, gender and age. This implies that attitudes to oral health are influenced by prevalent cultural attitudes more than by function.

[Examination of laser-treated tooth surfaces after exposure to acid].

PubMed

Beeking, P O; Herrmann, C; Zuhrt, R

1990-12-01

In principle it is possible to homogenize the enamel surface by melting structural elements with the continuous wave CO2 laser. An experimental caries model was used for testing the acid resistance of the laser exposed tooth surfaces. Laser-treatment and measured exposure to acid produced zones of homogeneous smelting with microcracks and disintegration symptoms. Underneath the melted region the heat leakage obviously causes photo-thermic++ effects determined by increased resistance to acid.

Efficacy of cold light bleaching using different bleaching times and their effects on human enamel.

PubMed

Wang, Wei; Zhu, Yuhe; Li, Jiajia; Liao, Susan; Ai, Hongjun

2013-01-01

This study investigated the efficacy of cold light bleaching using different bleaching times and the effects thereof on tooth enamel. Before and after bleaching, stained tooth specimens were subjected to visual and instrumental colorimetric assessments using Vita Shade Guide and spectrophotometric shade matching. Enamel surface alterations were examined using scanning electron microscopy (SEM) to analyze surface morphology, surface microhardness (SMH) measurement to determine changes in mechanical properties, and X-ray diffraction (XRD) to characterize post-bleaching enamel composition. Cold light bleaching successfully improved tooth color, with optimal efficacy when bleaching time was beyond 10 min. Significant differences in surface morphology were observed among the different bleaching times, but no significant differences were observed for enamel composition and surface microhardness among the different bleaching times. Results of this study revealed an association between the bleaching time of cold light bleaching and its whitening efficacy. Together with the results on enamel surface changes, this study provided positive evidence to support cold light bleaching as an in-office bleaching treatment.

Remineralization of artificial enamel lesions by theobromine.

PubMed

Amaechi, B T; Porteous, N; Ramalingam, K; Mensinkai, P K; Ccahuana Vasquez, R A; Sadeghpour, A; Nakamoto, T

2013-01-01

This study investigated the remineralization potential of theobromine in comparison to a standard NaF dentifrice. Three tooth blocks were produced from each of 30 teeth. Caries-like lesion was created on each block using acidified gel. A smaller block was cut from each block for baseline scanning electron microscopy imaging and electron-dispersive spectroscopy (EDS) analysis for surface Ca level. A tooth slice was cut from each lesion-bearing block for transverse microradiography (TMR) quantification of baseline mineral loss (Δz) and lesion depth (LD). Then baseline surface microhardness (SMH) of each lesion was measured. The three blocks from each tooth were assigned to three remineralizing agents: (1) artificial saliva; (2) artificial saliva with theobromine (0.0011 mol/l), and (3) NaF toothpaste slurry (0.0789 mol/l F). Remineralization was conducted using a pH cycling model with storage in artificial saliva. After a 28-day cycle, samples were analyzed using EDS, TMR, and SMH. Intragroup comparison of pre- and posttest data was performed using t tests (p < 0.05). Intergroup comparisons were performed by post hoc multistep comparisons (Tukey). SMH indicated significant (p < 0.01) remineralization only with theobromine (38 ± 32%) and toothpaste (29 ± 16%). With TMR (Δz/lD), theobromine and toothpaste exhibited significantly (p < 0.01) higher mineral gain relative to artificial saliva. With SMH and TMR, remineralization produced by theobromine and toothpaste was not significantly different. With EDS, calcium deposition was significant in all groups, but not significantly different among the groups (theobromine 13 ± 8%, toothpaste 10 ± 5%, and artificial saliva 6 ± 8%). The present study demonstrated that theobromine in an apatite-forming medium can enhance the remineralization potential of the medium. Copyright © 2013 S. Karger AG, Basel.

Enamel cracks evaluation - A method to predict tooth surface damage during the debonding.

PubMed

Dumbryte, Irma; Jonavicius, Tomas; Linkeviciene, Laura; Linkevicius, Tomas; Peciuliene, Vytaute; Malinauskas, Mangirdas

2015-01-01

The objective of this in vitro study was to evaluate the effect of the enamel cracks on the tooth damage during the debonding. Measurements of the cracks characteristics (visibility, direction, length, and location) were performed utilizing a scanning electron microscopy (SEM) technique and mathematically derived formulas (x=h/30, l=n*x) before and following the removal of mechanically retained metal and ceramic brackets. The likelihood of having greater extent enamel defects was higher for the teeth with pronounced cracks (odds vatios, OR=3.728), increased when the crack was located in more than one zone of the tooth (OR=1.998), and the inclination did not exceed 30-45° (OR=0.505). Using ceramic brackets the risk of greater amount tooth structure defects raised 1.45 times (OR=1.450). Enamel crack showing all these characteristics at the beginning of the orthodontic treatment and the use of ceramic brackets might predispose to higher risk of greater extent tooth surface damage after the debonding by 20.4%.

Monitoring tooth demineralization using a cross polarization optical coherence tomographic system with an integrated MEMS scanner

NASA Astrophysics Data System (ADS)

Fried, Daniel; Staninec, Michal; Darling, Cynthia; Kang, Hobin; Chan, Kenneth

2012-01-01

New methods are needed for the nondestructive measurement of tooth demineralization and remineralization to monitor the progression of incipient caries lesions (tooth decay) for effective nonsurgical intervention and to evaluate the performance of anti-caries treatments such as chemical treatments or laser irradiation. Studies have shown that optical coherence tomography (OCT) has great potential to fulfill this role since it can be used to measure the depth and severity of early lesions with an axial resolution exceeding 10-μm, it is easy to apply in vivo and it can be used to image the convoluted topography of tooth occlusal surfaces. In this paper we present early results using a new cross-polarization OCT system introduced by Santec. This system utilizes a swept laser source and a MEMS scanner for rapid acquisition of cross polarization images. Preliminary studies show that this system is useful for measurement of the severity of demineralization on tooth surfaces and for showing the spread of occlusal lesions under the dentinal-enamel junction.

Resin-bonded restorations: a strategy for managing anterior tooth loss in adolescence.

PubMed

Zitzmann, Nicola U; Özcan, Mutlu; Scherrer, Susanne S; Bühler, Julia M; Weiger, Roland; Krastl, Gabriel

2015-04-01

In children or adolescents with anterior tooth loss, space closure with the patient's own teeth should be considered as the first choice to avoid lifelong restorative needs. Thorough diagnostics and treatment planning are required when autotransplantation or orthodontic space closure is considered. If these options are not indicated and a single tooth implant restoration is considered, implant placement should be postponed until adulthood, particularly in young women and in patients with hyperdivergent skeletal growth pattern. A ceramic resin-bonded fixed dental prosthesis with 1 retainer is an excellent treatment solution for the interim period; it may also serve as a long-term restoration, providing that sound enamel structure is present, sufficient framework dimensions have been provided, adhesive cementation techniques have been meticulously applied, and functional contacts of the cantilever pontic avoided. In contrast, a resin-bonded fixed dental prosthesis with a metal framework and retentive preparation is indicated if the palatal enamel structure is compromised, interocclusal clearance is limited, splinting (such as after orthodontic treatment) is required, or more than 1 tooth has to be replaced. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Characterization of a human tooth with carious lesions using conventional and synchrotron radiation-based micro computed tomography

NASA Astrophysics Data System (ADS)

Dziadowiec, Iwona; Beckmann, Felix; Schulz, Georg; Deyhle, Hans; Müller, Bert

2014-09-01

In a dental office, every day X rays of teeth within the oral cavity are obtained. Caries induces a mineral loss and, therefore, becomes visible by reduced X-ray absorption. The detailed spatial distribution of the mineral loss, however, is inaccessible in conventional dental radiology, since the dose for such studies is intolerable. As a consequence, such measurements can only be performed after tooth extraction. We have taken advantage of synchrotron radiation-based micro computed tomography to characterize a human tooth with a rather small, natural caries lesion and an artificially induced lesion provoked by acidic etching. Both halves of the tooth were separately visualized from 2400 radiographs recorded at the beam line P07 / PETRA III (HASYLAB at DESY, Hamburg, Germany) with an asymmetric rotation axis at photon energy of 45 keV. Because of the setup, one finds an energy shift in the horizontal plane, to be corrected. After the appropriate three-dimensional registration of the data with the ones of the same crown using the better accessible phoenix nanotom® m of General Electric, Wunstorf, Germany, one can determine the joint histogram, which enable to calibrate the system with the conventional X-ray source.

The effect of increasing sodium fluoride concentrations on erosion and attrition of enamel and dentine in vitro.

PubMed

Austin, R S; Rodriguez, J M; Dunne, S; Moazzez, R; Bartlett, D W

2010-10-01

To investigate the effect of an aqueous sodium fluoride solution of increasing concentration on erosion and attrition of enamel and dentine in vitro. Enamel and dentine sections from caries-free human third molars were polished flat and taped (exposing a 3 mm x 3 mm area) before being randomly allocated to 1 of 5 groups per substrate (n=10/gp): G1 (distilled water control); G2 (225 ppm NaF); G3 (1450 ppm NaF); G4 (5000 ppm NaF); G5 (19,000 ppm NaF). All specimens were subjected to 5, 10 and 15 cycles of experimental wear [1 cycle=artificial saliva (2h, pH 7.0)+erosion (0.3% citric acid, pH 3.2, 5 min)+fluoride/control (5 min)+attrition (60 linear strokes in artificial saliva from enamel antagonists loaded to 300 g)]. Following tape removal, step height (SH) in mum was measured using optical profilometry. When the number of cycles increased the amount of tooth surface loss increased significantly in enamel and dentine after attrition and erosion and for dentine after attrition. Attrition and erosion resulted in greater surface loss than attrition alone after 15 cycles of experimental wear of enamel. 5000 ppm and 19,000 ppm sodium fluoride solutions had a protective effect on erosive and attritional enamel tooth wear in vitro, however no other groups showed significant differences. The more intensive the fluoride regime the more protection was afforded to enamel from attrition and erosion. However, in this study no such protective effect was demonstrated for dentine. Copyright 2010 Elsevier Ltd. All rights reserved.

Patient Stratification for Preventive Care in Dentistry

PubMed Central

Giannobile, W.V.; Braun, T.M.; Caplis, A.K.; Doucette-Stamm, L.; Duff, G.W.; Kornman, K.S.

2013-01-01

Prevention reduces tooth loss, but little evidence supports biannual preventive care for all adults. We used risk-based approaches to test tooth loss association with 1 vs. 2 annual preventive visits in high-risk (HiR) and low-risk (LoR) patients. Insurance claims for 16 years for 5,117 adults were evaluated retrospectively for tooth extraction events. Patients were classified as HiR for progressive periodontitis if they had ≥ 1 of the risk factors (RFs) smoking, diabetes, interleukin-1 genotype; or as LoR if no RFs. LoR event rates were 13.8% and 16.4% for 2 or 1 annual preventive visits (absolute risk reduction, 2.6%; 95%CI, 0.5% to 5.8%; p = .092). HiR event rates were 16.9% and 22.1% for 2 and 1 preventive visits (absolute risk reduction, 5.2%; 95%CI, 1.8% to 8.4%; p = .002). Increasing RFs increased events (p < .001). Oral health care costs were not increased by any single RF, regardless of prevention frequency (p > .41), but multiple RFs increased costs vs. no (p < .001) or 1 RF (p = .001). For LoR individuals, the association between preventive dental visits and tooth loss was not significantly different whether the frequency was once or twice annually. A personalized medicine approach combining gene biomarkers with conventional risk factors to stratify populations may be useful in resource allocation for preventive dentistry (ClinicalTrials.gov, NCT01584479). PMID:23752171

A comparison of female and male oral health in skeletal populations from late Roman Britain: implications for diet.

PubMed

Bonsall, L

2014-12-01

Textual sources from the Roman period point to the existence of dietary differences between the sexes. The aim of this study was to assess the palaeopathological evidence for such gender differences in dietary habits in Roman Britain by comparing the oral health of sexed individuals from two late Romano-British sites (Ancaster, Lincolnshire, and Winchester, Hampshire, England). Eighty-seven females (1243 teeth and 1950 sockets) and 112 males (1984 teeth and 2903 sockets) were examined for the presence of five dento-alveolar conditions, namely caries, calculus, periapical lesions, periodontal disease, and antemortem tooth loss. The frequency of each condition was calculated at the per individual and per tooth/socket level, and the results were compared between the sexes using Fisher's exact tests. Caries and antemortem tooth loss were slightly more common among women, but differences between the sexes were generally not significant. Males experienced higher rates of calculus and periodontal disease. There were no sex differences in the frequency of periapical lesions. Comparable rates of caries, periapical lesions and antemortem tooth loss in females and males indicate broad similarity in the diets of men and women. The greater levels of calculus and periodontal disease in males might point to some dietary differences, but could also be explained by non-dietary factors. Overall, the findings suggest that significant gender differences in diet, described in some contemporaneous textual sources, were not widely observed in Roman Britain. Copyright © 2014 Elsevier Ltd. All rights reserved.

Tooth loss in 1535 treated periodontal patients.

PubMed

Nabers, C L; Stalker, W H; Esparza, D; Naylor, B; Canales, S

1988-05-01

Of 1535 treated recall patients surveyed over an average time of 12.9 years since treatment was completed, 1371 had lost no teeth from periodontal disease. The total number of teeth lost was 444, with the average tooth loss for the 1535 patients being 0.29. In the three full arch splinted cases, the loss rate was 14.67 teeth per patient. Patients treated without any excisional or flap surgical procedures made up 26.5% of those surveyed, whereas 73.5% had required various surgical procedures. No attempt was made to compare different pocket therapy procedures. Although many patients developed recurrent periodontal problems during recall, only 15.9% of the 1535 patients required surgical retreatment. Teeth that were originally given a doubtful prognosis often were responsible for recurrent problems and sometimes required extraction.

Protocol for measurement of enamel loss from brushing with an anti-erosive toothpaste after an acidic episode.

PubMed

Dehghan, Mojdeh; Vieira Ozorio, Jose Estevam; Chanin, Simon; Tantbirojn, Daranee; Versluis, Antheunis; Garcia-Godoy, Franklin

2017-01-01

Tooth erosion from an acidic insult may be exacerbated by toothbrushing. The purposes of this study were to develop an in vitro methodology to measure enamel loss after brushing immediately following an acidic episode and to investigate the effect of brushing with an anti-erosive toothpaste. The null hypotheses tested were that tooth erosion after brushing with the toothpaste would not be different from brushing with water and that a 1-hour delay before brushing would not reduce tooth erosion. Forty bovine enamel slabs were embedded, polished, and subjected to baseline profilometry. Specimens were bathed in hydrochloric acid for 10 minutes to simulate stomach acid exposure before post-acid profilometry. Toothbrushing was then simulated with a cross-brushing machine and followed by postbrushing profilometry. Group 1 was brushed with water; group 2 was brushed with a 50:50 toothpaste-water slurry; and groups 3 and 4 were immersed in artificial saliva for 1 hour before brushing with water or the toothpaste slurry, respectively. The depth of enamel loss was analyzed and compared using 1-way analysis of variance and post hoc testing (α = 0.05). Greater enamel loss was measured in groups brushed with toothpaste than in groups brushed with water. One-hour immersion in artificial saliva significantly reduced enamel loss when teeth were brushed with water (group 3; P < 0.05) but not with toothpaste (group 4). This study established a protocol for measuring enamel loss resulting from erosion followed by toothbrush abrasion. The results confirmed the abrasive action of toothpaste on acid-softened enamel.

To Analyse the Erosive Potential of Commercially Available Drinks on Dental Enamel and Various Tooth Coloured Restorative Materials – An In-vitro Study

PubMed Central

Jindal, Ritu; Mahajan, Sandeep; Sandhu, Sanam; Sharma, Sunila; Kaur, Rajwinder

2016-01-01

Introduction With the enormous change in life style pattern of a common man through the past few decades, there has been proportional variation in the amount and frequency of consumption of drinks. An increased consumption of these drinks will concurrently increase enamel surface roughness by demineralization, resulting in hypersensitivity and elevated caries risk. Aim The present study was designed to evaluate the erosive potential of commercially available drinks on tooth enamel and various tooth coloured restorative materials. Materials and Methods Extracted human teeth were taken and divided into four groups i.e. tooth enamel, glass ionomer cement, composite and compomer. Four commercially available drinks were chosen these were Coca -Cola, Nimbooz, Frooti and Yakult. The pH of each drink was measured. Each group was immersed in various experimental drinks for a period of 14 days. The erosive potential of each drink was measured by calculating the change in average surface roughness of these groups after the immersion protocol in various drinks. The data analysis was done by One Way Anova, Post-Hoc Bonferroni, and paired t –test. Results Group II-GIC showed highest values for mean of change in average surface roughness and the values were statistically significant (p<0.001) with tooth enamel, composite and compomer (p=0.002). Coca-cola showed the highest erosive potential and Yakult showed the lowest, there was no statistical significant difference between the results shown by Yakult and Frooti. Conclusion Characteristics which may promote erosion of enamel and tooth coloured restorative materials were surface texture of the material and pH of the drinks. PMID:27437343

Interactions between dodecyl phosphates and hydroxyapatite or tooth enamel: relevance to inhibition of dental erosion.

PubMed

Jones, Siân B; Barbour, Michele E; Shellis, R Peter; Rees, Gareth D

2014-05-01

Tooth surface modification is a potential method of preventing dental erosion, a form of excessive tooth wear facilitated by softening of tooth surfaces through the direct action of acids, mainly of dietary origin. We have previously shown that dodecyl phosphates (DPs) effectively inhibit dissolution of native surfaces of hydroxyapatite (the type mineral for dental enamel) and show good substantivity. However, adsorbed saliva also inhibits dissolution and DPs did not augment this effect, which suggests that DPs and saliva interact at the hydroxyapatite surface. In the present study the adsorption and desorption of potassium and sodium dodecyl phosphates or sodium dodecyl sulphate (SDS) to hydroxyapatite and human tooth enamel powder, both native and pre-treated with saliva, were studied by high performance liquid chromatography-mass Spectrometry. Thermo gravimetric analysis was used to analyse residual saliva and surfactant on the substrates. Both DPs showed a higher affinity than SDS for both hydroxyapatite and enamel, and little DP was desorbed by washing with water. SDS was readily desorbed from hydroxyapatite, suggesting that the phosphate head group is essential for strong binding to this substrate. However, SDS was not desorbed from enamel, so that this substrate has surface properties different from those of hydroxyapatite. The presence of a salivary coating had little or no effect on adsorption of the DPs, but treatment with DPs partly desorbed saliva; this could account for the failure of DPs to increase the dissolution inhibition due to adsorbed saliva. Copyright © 2014 Elsevier B.V. All rights reserved.

Influence of unilateral tooth loss in the temporomandibular joint and masseter muscle of rabbits.

PubMed

Im, Jae-Hyung; Kim, Su-Gwan; Oh, Ji-Su; Lim, Sung-Chul; Ha, Jung-Min

2012-07-01

The purpose of this study was to evaluate the influence of the masticatory system in patients with missing teeth. The influence of tooth loss on the masticatory system was analyzed with the use of bone scintigraphy ((99m)Tc-MDP) and histochemistry. Eight white rabbits (New Zealand, 12 weeks old) were used. The rabbits were divided into 2 groups: 6 weeks and 12 weeks. Teeth were extracted unilaterally in each rabbit under general anesthesia. Six and 12 weeks after extraction, scintigraphy was conducted, and the rabbits were killed and their masseter muscles removed for histochemical analysis. The results of bone metabolism (relative ratio) measured by bone scintigraphy were 48.27% at extraction sites and 51.73% at nonextraction sites at 6 weeks and 39.96% at extraction sites and 60.04% at nonextraction sites at 12 weeks. There was a significant difference at 12 weeks (P < .05). Tissue calcium contents and osteoclast counts showed different results between the extraction and nonextraction sites, but these differences did not reach statistical significance. The bone metabolism of temporomandibular joints and histochemical aspects of masticatory muscles may be associated with occlusal alterations following tooth loss. Copyright © 2012 Elsevier Inc. All rights reserved.

Effect of tray-based and trayless tooth whitening systems on microhardness of enamel surface and subsurface.

PubMed

Teixeira, Erica C N; Ritter, André V; Thompson, Jeffrey Y; Leonard, Ralph H; Swift, Edward J

2004-12-01

To evaluate the effect of tray-based and trayless tooth whitening systems on surface and subsurface microhardness of human enamel. Enamel slabs were obtained from recently extracted human third molars. Specimens were randomly assigned to six groups according to tooth whitening treatment (n = 10): 6.0% hydrogen peroxide (HP) (Crest Whitestrips), 6.5% HP (Crest Professional Whitestrips), 7.5% HP (Day White Excel 3), 9.5% HP (Day White Excel 3), 10% carbamide peroxide (Opalescence), and a control group (untreated). Specimens were treated for 14 days following manufacturers' recommended protocols, and were immersed in artificial saliva between treatments. Enamel surface Knoop microhardness (KHN) was measured immediately before treatment, and at days 1, 7, and 14 of treatment. After treatment, subsurface microhardness was measured at depths of 50-500 microm. Data were analyzed for statistical significance using analysis of variance. Differences in microhardness for treated vs. untreated enamel surface were not statistically significant at any time interval. For 6.5% and 9.5% HP, there was a decrease in surface microhardness values during treatment, but at the end of treatment the microhardness values were not statistically different from the baseline values. For the enamel subsurface values, no differences were observed between treated vs. untreated specimens at each depth. Trayless and tray-based tooth whitening treatments do not significantly affect surface or subsurface enamel microhardness.

Selective removal of demineralized enamel using a CO2 laser coupled with near-IR reflectance imaging

NASA Astrophysics Data System (ADS)

Tom, Henry; Chan, Kenneth H.; Saltiel, Daniel; Fried, Daniel

2015-02-01

Detection and diagnosis of early dental caries lesions can be difficult due to variable tooth coloration, staining of the teeth and poor contrast between sound and demineralized enamel. These problems can be overcome by using near-infrared (NIR) imaging. Previous studies have demonstrated that lasers can be integrated with NIR imaging devices, allowing image-guided ablation. The aim of this study was to demonstrate that NIR light at 1500 - 1700 nm can be used to guide a 9.3-μm CO2 laser for the selective ablation of early demineralization on tooth occlusal surfaces. The occlusal surfaces of ten sound human molars were used in this in-vitro study. Shallow simulated caries lesions of varying depth and position were produced on tooth occlusal surfaces using a demineralization solution. Sequential NIR reflectance images at 1500 - 1700 nm were used to guide the laser for selective ablation of the lesion areas. Digital microscopy and polarization sensitive optical coherence tomography (PS-OCT) were used to assess the selectivity of removal. This study demonstrates that high contrast NIR reflectance images can be used for the image-guided laser ablation of early demineralization from tooth occlusal surfaces.

Tooth enamel remineralization

NASA Astrophysics Data System (ADS)

Arends, J.; Ten Cate, J. M.

1981-05-01

In this paper a survey is given on tooth remineralization from remineralizing solutions and from saliva. The substrate, sound tooth enamel, is described from a chemical as well as from an ultrastructural point of view. Because saliva plays a crucial role in in vivo remineralizations, the most relevant properties of saliva, such as the thermodynamic stabilities with respect to calcium phosphates of interest, are considered. Tooth remineralization can be divided into three main types: lesion remineralization, surface softened remineralization and etched enamel remineralization. The main emphasis in this survey is given to lesion and surface softened remineralization which are the most important from a practical view point. In these two cases, the reaction order, the activation energy and the mechanism are discussed as well as the ultrastructure of remineralized material, the influence of various agents (especially F -)and differences between in vitro and in vivo data.

Genomewide Identification of Essential Genes and Fitness Determinants of Streptococcus mutans UA159

PubMed Central

Zeng, Lin; Culp, David J.

2018-01-01

ABSTRACT Transposon mutagenesis coupled with next-generation DNA sequencing (Tn-seq) is a powerful tool for discovering regions of the genome that are required for the survival of bacteria in different environments. We adapted this technique to the dental caries pathogen Streptococcus mutans UA159 and identified 11% of the genome as essential, with many genes encoding products required for replication, translation, lipid metabolism, and cell wall biogenesis. Comparison of the essential genome of S. mutans UA159 with those of selected other streptococci for which such information is available revealed several metabolic pathways and genes that are required in S. mutans, but not in some Streptococcus spp. We further identified genes that are essential for sustained growth in rich or defined medium, as well as for persistence in vivo in a rodent model of oral infection. Collectively, our results provide a novel and comprehensive view of the genes required for essential processes of S. mutans, many of which could represent potential targets for therapeutics. IMPORTANCE Tooth decay (dental caries) is a common cause of pain, impaired quality of life, and tooth loss in children and adults. It begins because of a compositional change in the microorganisms that colonize the tooth surface driven by repeated and sustained carbohydrate intake. Although several bacterial species are associated with tooth decay, Streptococcus mutans is the most common cause. Therefore, it is important to identify biological processes that contribute to the survival of S. mutans in the human mouth, with the aim of disrupting the processes with antimicrobial agents. We successfully applied Tn-seq to S. mutans, discovering genes that are required for survival, growth, and persistence, both in laboratory environments and in a mouse model of tooth decay. This work highlights new avenues for the control of an important human pathogen. PMID:29435491

Probing depth, attachment loss and gingival recession. Findings from a clinical examination in Ushiku, Japan.

PubMed

Yoneyama, T; Okamoto, H; Lindhe, J; Socransky, S S; Haffajee, A D

1988-10-01

The present investigation describes probing pocket depth, probing attachment level and recession data from 319 randomly selected subjects, aged 20-79 years, from Ushiku, Japan. The findings are reported as mean values, frequency distributions and percentile plots of the 3 parameters at buccal, interproximal and lingual surfaces of single rooted (incisors, canines, premolars) and molar teeth. Inter-as well as intra-examiner errors for probing pocket depth and probing attachment levels were assessed and found to be small. The data reported revealed that practically all subjects studied had one or more sites in the dentition affected by destructive periodontal disease and that the severity of disease increased with age. It was further observed that in each age group, molars had suffered more attachment loss than single rooted teeth and that the interproximal surfaces as a rule had lost more periodontal tissue support than corresponding buccal and lingual surfaces. The attachment loss difference observed between different surfaces of a given tooth or a group of teeth, however, was comparatively small. In the age groups between 20-59 years, advanced destructive periodontal disease was found in a small subgroup of the subject sample, while after the age of 60 years, widespread destructive periodontitis was common. An attempt was made to examine the progression of destructive disease with age by comparing the frequency distributions of sites with attachment loss of greater than or equal to 3 mm in subjects of different age groups. The data suggested that in younger subject groups, progression was confined to a subset of individuals, while in older age groups, more subjects and sites became involved. A major feature of destructive periodontal disease in older individuals was the accompaniment of attachment loss with recession at the gingival margin. Deep pockets were relatively infrequently detected, while advanced loss of attachment (with recession) occurred at many sites.

Morphology and mechanics of the teeth and jaws of white-spotted bamboo sharks (Chiloscyllium plagiosum).

PubMed

Ramsay, Jason B; Wilga, Cheryl D

2007-08-01

The teeth of white-spotted bamboo sharks (Chiloscyllium plagiosum) are used to clutch soft-bodied prey and crush hard prey; however, the dual function is not evident from tooth morphology alone. Teeth exhibit characteristics that are in agreement with a clutching-type tooth morphology that is well suited for grasping and holding soft-bodied prey, but not for crushing hard prey. The dual role of this single tooth morphology is facilitated by features of the dental ligament and jaw joint. Tooth attachment is flexible and elastic, allowing movement in both sagittal and frontal planes. During prey capture spike-like tooth cusps pierce the flesh of soft prey, thereby preventing escape. When processing prey harder than the teeth can pierce the teeth passively depress, rotating inward towards the oral cavity such that the broader labial faces of the teeth are nearly parallel to the surface of the jaws and form a crushing surface. Movement into the depressed position increases the tooth surface area contacting prey and decreases the total stress applied to the tooth, thereby decreasing the risk of structural failure. This action is aided by a jaw joint that is ventrally offset from the occlusal planes of the jaws. The offset joint position allows many teeth to contact prey simultaneously and orients force vectors at contact points between the jaws and prey in a manner that shears or rolls prey between the jaws during a bite, thus, aiding in processing while reducing forward slip of hard prey from the mouth. Together the teeth, dental ligament, and jaws form an integrated system that may be beneficial to the feeding ecology of C. plagiosum, allowing for a diet that includes prey of varying hardness and elusiveness. (c) 2007 Wiley-Liss, Inc.

Comparative evaluation of surface topography of tooth prepared using erbium, chromium: Yttrium, scandium, gallium, garnet laser and bur and its clinical implications.

PubMed

Verma, Mahesh; Kumari, Pooja; Gupta, Rekha; Gill, Shubhra; Gupta, Ankur

2015-01-01

Erbium, chromium: Yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser has been successfully used in the ablation of dental hard and soft tissues. It has been reported that this system is also useful for preparing tooth surfaces and etching, but no consensus exist in the literature regarding the advantage of lasers over conventional tooth preparation technique. Labial surfaces of 25 extracted human maxillary central incisors were divided into two halves. Right half was prepared with diamond bur and left half with Er, Cr; YSGG laser and a reduction of 0.3-0.5 mm was carried out. Topography of prepared surfaces of five teeth were examined under scanning electron microscope (SEM). The remaining samples were divided into 4 groups of 10 specimens each based on the surface treatment received: One group was acid etched and other was nonetched. Composite resin cylinders were bonded on prepared surfaces and shear bond strength was assessed using a universal testing machine. The SEM observation revealed that the laser prepared surfaces were clean, highly irregular and devoid of a smear layer. Bur prepared surfaces were relatively smooth but covered with smear layer. Highest bond strength was shown by laser prepared acid etched group, followed by bur prepared the acid etched group. The bur prepared nonacid etched group showed least bond strength. Er, Cr: YSGG laser can be used for preparing tooth and bond strength value achieved by laser preparation alone without surface treatment procedure lies in the range of clinical acceptability.

In vitro Assessment of Influence of Various Bleaching Protocols on the Strength of Ceramic Orthodontic Brackets bonded to Bleached Tooth Surface: A Comparative Study.

PubMed

Iska, Divya; Devanna, Raghu; Singh, Madhvi; Chitumalla, Rajkiran; Balasubramanian, Sai C Bala; Goutam, Manish

2017-12-01

Esthetics is one of the common issues because of which patients consult dental orthodontic treatment. Two ways of tooth bleaching are available these days, which includes in-office bleach and home bleach. Various bleaching protocols are available these days for treating the tooth surfaces. Hence, we planned the present study for investigating the impact of various intracoronal bleaching protocols on shear bond strength of ceramic brackets bonded to tooth surface after bleaching. The present study included assessment of 100 extracted maxillary central incisors with the integrated buccal surface. A resin block was made and individual teeth were embedded in each block. Root canal therapy procedure was performed in all the teeth, after which 2 mm short of tooth apex up to the level of cementoenamel junction, removal of the root canal filling was done. All the samples were broadly divided into four study groups with 25 samples in each group. Bleaching procedure was carried in all the samples intracoronally followed by testing of shear bond strength using universal force testing machine. Following the modified adhesive remnant index (AI), assessment of remaining adhesive on the brackets was done. All the results were compiled and analyzed by Statistical Package for the Social Sciences (SPSS) software version 17.0. In the control group, mean shear bond strength was found to be 17.9 MPa. While comparing the carbamide peroxide (CP) group with sodium perborate study group, we observed a statistically significant difference. Nonsignificant results were obtained while comparing the shear bond strength in between sodium perborate group and hydrogen peroxide (HP) group. Intracoronal bleaching does affect the shear bond strength of ceramic brackets. Sodium perborate bleaching influences shear bond strength more strongly than other bleaching agents such as CP and HP. In patients undergoing orthodontic treatment, HP is a preferred agent where bleaching has to be followed by orthodontic bonding to the tooth surface.

WNT10A mutation results in severe tooth agenesis in a family of three sisters.

PubMed

Abid, M F; Simpson, M A; Barbosa, I A; Seppala, M; Irving, M; Sharpe, P T; Cobourne, M T

2018-06-21

To identify the genetic basis of severe tooth agenesis in a family of three affected sisters. A family of three sisters with severe tooth agenesis was recruited for whole-exome sequencing to identify potential genetic variation responsible for this penetrant phenotype. The unaffected father was tested for specific mutations using Sanger sequencing. Gene discovery was supplemented with in situ hybridization to localize gene expression during human tooth development. We report a nonsense heterozygous mutation in exon 2 of WNT10A c.321C>A[p.Cys107*] likely to be responsible for the severe tooth agenesis identified in this family through the creation of a premature stop codon, resulting in truncation of the amino acid sequence and therefore loss of protein function. In situ hybridization showed expression of WNT10A in odontogenic epithelium during the early and late stages of human primary tooth development. WNT10A has previously been associated with both syndromic and non-syndromic forms of tooth agenesis, and this report further expands our knowledge of genetic variation underlying non-syndromic forms of this condition. We also demonstrate expression of WNT10A in the epithelial compartment of human tooth germs during development. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Autocrine and paracrine Shh signaling are necessary for tooth morphogenesis, but not tooth replacement in snakes and lizards (Squamata).

PubMed

Handrigan, Gregory R; Richman, Joy M

2010-01-01

Here we study the role of Shh signaling in tooth morphogenesis and successional tooth initiation in snakes and lizards (Squamata). By characterizing the expression of Shh pathway receptor Ptc1 in the developing dentitions of three species (Eublepharis macularius, Python regius, and Pogona vitticeps) and by performing gain- and loss-of-function experiments, we demonstrate that Shh signaling is active in the squamate tooth bud and is required for its normal morphogenesis. Shh apparently mediates tooth morphogenesis by separate paracrine- and autocrine-mediated functions. According to this model, paracrine Shh signaling induces cell proliferation in the cervical loop, outer enamel epithelium, and dental papilla. Autocrine signaling within the stellate reticulum instead appears to regulate cell survival. By treating squamate dental explants with Hh antagonist cyclopamine, we induced tooth phenotypes that closely resemble the morphological and differentiation defects of vestigial, first-generation teeth in the bearded dragon P. vitticeps. Our finding that these vestigial teeth are deficient in epithelial Shh signaling further corroborates that Shh is needed for the normal development of teeth in snakes and lizards. Finally, in this study, we definitively refute a role for Shh signaling in successional dental lamina formation and conclude that other pathways regulate tooth replacement in squamates.

Clinical measurement of tooth wear: Tooth wear indices

PubMed Central

López-Frías, Francisco J.; Castellanos-Cosano, Lizett; Martín-González, Jenifer; Llamas-Carreras, José M.

2012-01-01

Attrition, erosion, and abrasion result in alterations to the tooth and manifest as tooth wear. Each classification corresponds to a different process with specific clinical features. Classifications made so far have no accurate prevalence data because the indexes do not necessarily measure a specific etiology, or because the study populations can be diverse in age and characteristics. Tooth wears (attrition, erosion and abrasion) is perceived internationally as a growing problem. However, the interpretation and comparison of clinical and epidemiological studies, it is increasingly difficult because of differences in terminology and the large number of indicators/indices that have been developed for the diagnosis, classification and monitoring of the loss of dental hard tissue. These indices have been designed to identify increasing severity and are usually numerical, none have universal acceptance, complicating the evaluation of the true increase in prevalence reported. This article considers the ideal requirements for an erosion index. A literature review is conducted with the aim of analyzing the evolution of the indices used today and discuss whether they meet the clinical needs and research in dentistry. Key words:Tooth wear, tooth wear indices, attrition, erosion, abrasion, abfraction. PMID:24558525

Association between added sugar intake and dental caries in Yup'ik children using a novel hair biomarker.

PubMed

Chi, Donald L; Hopkins, Scarlett; O'Brien, Diane; Mancl, Lloyd; Orr, Eliza; Lenaker, Dane

2015-10-09

Dental caries (tooth decay) is a significant public health problem in Alaska Native children. Dietary added sugars are considered one of the main risk factors. In this cross-sectional pilot study, we used a validated hair-based biomarker to measure added sugar intake in Alaska Native Yup'ik children ages 6-17 years (N = 51). We hypothesized that added sugar intake would be positively associated with tooth decay. A 66-item parent survey was administered, a hair sample was collected from each child, and a dental exam was conducted. Added sugar intake (grams/day) was measured from hair samples using a linear combination of carbon and nitrogen ratios. We used linear and log-linear regression models with robust standard errors to test our hypothesis that children with higher added sugar intake would have a higher proportion of carious tooth surfaces. The mean proportion of carious tooth surfaces was 30.8 % (standard deviation: 23.2 %). Hair biomarker-based added sugar intake was associated with absolute (6.4 %; 95 % CI: 1.2 %, 11.6 %; P = .02) and relative increases in the proportion of carious tooth surfaces (24.2 %; 95 % CI: 10.6 %, 39.4 %; P < .01). There were no associations between self-reported measures of sugar-sweetened food and beverage intake and tooth decay. Added sugar intake as assessed by hair biomarker was significantly and positively associated with tooth decay in our sample of Yup'ik children. Self-reported dietary measures were not associated tooth decay. Most added sugars were from sugar-sweetened fruit drinks consumed at home. Future dietary interventions aimed at improving the oral health of Alaska Native children should consider use of objective biomarkers to assess and measure changes in home-based added sugar intake, particularly sugar-sweetened fruit drinks.

Immediate esthetic crown with a facet of the extracted element

PubMed Central

Di Giacomo, Giovanni de Almeida Prado; Magalhães, Amanda; Ajzen, Sergio

2014-01-01

The present report describes a case of implant loading with an immediate temporary crown. The buccal crown surface was removed from the extracted tooth to obtain an aesthetically satisfactory result. After periodontal treatment, tooth 21 appeared proclined and showed Grade 3 mobility, indicating the need for its extraction. The remaining bone was imaged using computed tomography, and virtual surgical planning was performed using these results. The implant was immediately loaded postextraction into the fresh alveolus without a graft and flap procedure. The temporary tooth, which was manufactured using the extracted buccal surface, was a simple, fast, and low cost procedure that produced an excellent esthetic outcome. PMID:25202225

Distinguishing and diagnosing contemporary and conventional features of dental erosion.

PubMed

Bassiouny, Mohamed A

2014-01-01

The vast number and variety of erosion lesions encountered today require reconsideration of the traditional definition. Dental erosion associated with modern dietary habits can exhibit unique features that symbolize a departure from the decades-old conventional image known as tooth surface loss. The extent and diversity of contemporary erosion lesions often cause conflicting diagnoses. Specific examples of these features are presented in this article. The etiologies, genesis, course of development, and characteristics of these erosion lesions are discussed. Contemporary and conventional erosion lesions are distinguished from similar defects, such as mechanically induced wear, carious lesions, and dental fluorosis, which affect the human dentition.

Small-Scale Fabrication of Biomimetic Structures for Periodontal Regeneration

PubMed Central

Green, David W.; Lee, Jung-Seok; Jung, Han-Sung

2016-01-01

The periodontium is the supporting tissues for the tooth organ and is vulnerable to destruction, arising from overpopulating pathogenic bacteria and spirochaetes. The presence of microbes together with host responses can destroy large parts of the periodontium sometimes leading tooth loss. Permanent tissue replacements are made possible with tissue engineering techniques. However, existing periodontal biomaterials cannot promote proper tissue architectures, necessary tissue volumes within the periodontal pocket and a “water-tight” barrier, to become clinically acceptable. New kinds of small-scale engineered biomaterials, with increasing biological complexity are needed to guide proper biomimetic regeneration of periodontal tissues. So the ability to make compound structures with small modules, filled with tissue components, is a promising design strategy for simulating the anatomical complexity of the periodotium attachment complexes along the tooth root and the abutment with the tooth collar. Anatomical structures such as, intima, adventitia, and special compartments such as the epithelial cell rests of Malassez or a stellate reticulum niche need to be engineered from the start of regeneration to produce proper periodontium replacement. It is our contention that the positioning of tissue components at the origin is also necessary to promote self-organizing cell–cell connections, cell–matrix connections. This leads to accelerated, synchronized and well-formed tissue architectures and anatomies. This strategy is a highly effective preparation for tackling periodontitis, periodontium tissue resorption, and to ultimately prevent tooth loss. Furthermore, such biomimetic tissue replacements will tackle problems associated with dental implant support and perimimplantitis. PMID:26903872

Clinical Performance of a New Biomimetic Double Network Material

PubMed Central

Dirxen, Christine; Blunck, Uwe; Preissner, Saskia

2013-01-01

Background: The development of ceramics during the last years was overwhelming. However, the focus was laid on the hardness and the strength of the restorative materials, resulting in high antagonistic tooth wear. This is critical for patients with bruxism. Objectives: The purpose of this study was to evaluate the clinical performance of the new double hybrid material for non-invasive treatment approaches. Material and Methods: The new approach of the material tested, was to modify ceramics to create a biomimetic material that has similar physical properties like dentin and enamel and is still as strong as conventional ceramics. Results: The produced crowns had a thickness ranging from 0.5 to 1.5 mm. To evaluate the clinical performance and durability of the crowns, the patient was examined half a year later. The crowns were still intact and soft tissues appeared healthy and this was achieved without any loss of tooth structure. Conclusions: The material can be milled to thin layers, but is still strong enough to prevent cracks which are stopped by the interpenetrating polymer within the network. Depending on the clinical situation, minimally- up to non-invasive restorations can be milled. Clinical Relevance: Dentistry aims in preservation of tooth structure. Patients suffering from loss of tooth structure (dental erosion, Amelogenesis imperfecta) or even young patients could benefit from minimally-invasive crowns. Due to a Vickers hardness between dentin and enamel, antagonistic tooth wear is very low. This might be interesting for treating patients with bruxism. PMID:24167534

The compression dome concept: the restorative implications.

PubMed

Milicich, Graeme

2017-01-01

Evidence now supports the concept that the enamel on a tooth acts like a compression dome, much like the dome of a cathedral. With an overlying enamel compression dome, the underlying dentin is protected from damaging tensile forces. Disruption of a compression system leads to significant shifts in load pathways. The clinical restorative implications are significant and far-reaching. Cutting the wrong areas of a tooth exposes the underlying dentin to tensile forces that exceed natural design parameters. These forces lead to crack propagation, causing flexural pain and eventual fracture and loss of tooth structure. Improved understanding of the microanatomy of tooth structure and where it is safe to cut teeth has led to a revolution in dentistry that is known by several names, including microdentistry, minimally invasive dentistry, biomimetic dentistry, and bioemulation dentistry. These treatment concepts have developed due to a coalescence of principles of tooth microanatomy, material science, adhesive dentistry, and reinforcing techniques that, when applied together, will allow dentists to repair a compromised compression dome so that it more closely replicates the structure of the healthy tooth.

A family with autosomal dominant mutilating neuropathy not linked to either Charcot-Marie-Tooth disease type 2B (CMT2B) or hereditary sensory neuropathy type I (HSN I) loci.

PubMed

Bellone, Emilia; Rodolico, Carmelo; Toscano, Antonio; Di Maria, Emilio; Cassandrini, Denise; Pizzuti, Antonio; Pigullo, Simona; Mazzeo, Anna; Macaione, Vincenzo; Girlanda, Paolo; Vita, Giuseppe; Ajmar, Franco; Mandich, Paola

2002-03-01

Sensory loss and ulcero-mutilating features have been observed in hereditary sensory neuropathy type I and in hereditary motor and sensory neuropathy type IIB, also referred as Charcot-Marie-Tooth disease type 2B. To date two loci associated with ulcero-mutilating neuropathy have been described: CMT2B at 3q13-q22 and HSN I at 9q22.1-q22.3. We performed linkage analysis with chromosomal markers representing the hereditary sensory neuropathy type I and Charcot-Marie-Tooth disease type 2B loci on an Italian family with a severe distal sensory loss leading to an ulcero-mutilating peripheral neuropathy. Negative likelihood-of-odds scores excluded any evidence of linkage to both chromosome 3q13 and chromosome 9q22 markers, confirming the genetic heterogeneity of this clinical entity and the presence of a third locus responsible for ulcero-mutilating neuropathies.

A Study of the Potential to Detect Caries Lesions at the White-Spot Stage Using V(Z) Technique

NASA Astrophysics Data System (ADS)

Bakulin, E. Y.; Denisova, L. A.; Maev, R. Gr.

Current wide-spread methods of non-destructive methods of caries diagnostics, such as X-ray techniques, do not provide the possibility to efficiently detect enamel caries lesions at the beginning ("white-spot") stage, when the tooth tissue is only slightly altered and no loss of the tissue occurs. Therefore, it is of paramount importance to develop new, more sensitive methods of caries diagnostics. In this paper, certain aspects of the ultrasonic approach to the problem are discussed - in particular, detection of the enamel's surface caries at the white-spot stage with a focused ultrasonic sensor positioned in front of the caries lesion (without cross-sectioning the tooth). Theoretical model using V(z) approach for layered media was applied to perform computer simulations resulting in V(z) curves for the different parameters of carious tissue and the degree of degradation. The curves were analyzed and it was shown that, comparing to a short-pulse/echo technique, V(z) approach provides much better distinction between sound and carious enamel and even makes possible to evaluate the degree of demineralization.

Development of cyclic shedding teeth from semi-shedding teeth: the inner dental arcade of the stem osteichthyan Lophosteus

NASA Astrophysics Data System (ADS)

Chen, Donglei; Blom, Henning; Sanchez, Sophie; Tafforeau, Paul; Märss, Tiiu; Ahlberg, Per E.

2017-05-01

The numerous cushion-shaped tooth-bearing plates attributed to the stem group osteichthyan Lophosteus superbus, which are argued here to represent an early form of the osteichthyan inner dental arcade, display a previously unknown and presumably primitive mode of tooth shedding by basal hard tissue resorption. They carry regularly spaced, recumbent, gently recurved teeth arranged in transverse tooth files that diverge towards the lingual margin of the cushion. Three-dimensional reconstruction from propagation phase-contrast synchrotron microtomography (PPC-SRµCT) reveals remnants of the first-generation teeth embedded in the basal plate, a feature never previously observed in any taxon. These teeth were shed by semi-basal resorption with the periphery of their bases retained as dentine rings. The rings are highly overlapped, which evidences tooth shedding prior to adding the next first-generation tooth at the growing edge of the plate. The first generation of teeth is thus diachronous. Successor teeth at the same sites underwent cyclical replacing and shedding through basal resorption, producing stacks of buried resorption surfaces separated by bone of attachment. The number and spatial arrangement of resorption surfaces elucidates that basal resorption of replacement teeth had taken place at the older tooth sites before the addition of the youngest first-generation teeth at the lingual margin. Thus, the replacement tooth buds cannot have been generated by a single permanent dental lamina at the lingual edge of the tooth cushion, but must have arisen either from successional dental laminae associated with the individual predecessor teeth, or directly from the dental epithelium of these teeth. The virtual histological dissection of these Late Silurian microfossils broadens our understanding of the development of the gnathostome dental systems and the acquisition of the osteichthyan-type of tooth replacement.

Effects of resistance form on attachment strength of resin-retained castings.

PubMed

Wilkes, P W; Shillingburg, H T; Johnson, D L

2000-01-01

This study evaluated the effects of tooth preparation design on resistance to dislodgment of a resin-bonded fixed partial denture (RBFPD). The variations of tooth preparation tested included axial coverage, retentive grooves, and an occlusal rest. Patterns of the tooth preparation designs were prepared and cast in a base metal alloy. Retainer patterns were waxed to refractory casts of metal dies, cast, finished and then bonded to the dies. The complete assemblies were loaded to failure on an Instron mechanical testing machine, and analysis indicated that retainers with occlusal rests were the most resistant. Grooves provided no statistically significant increase in resistance to failure of the cement. Increased axial coverage did not increase resistance to dislodgment. Successful fixed partial dentures (FPDs) depend on cast retainers to resist displacement of the restoration during function. Introduction of resin-bonded restorations opened the possibility of FPDs with minimal reduction of abutments. Specific questions concerning long term success and tooth preparation designs were prominent concerns. The influence of resistance form on overall stability of a restoration was also of particular interest. Buonocore established the foundation for retention of composite resins to acid-pitted enamel. Rochette used this technology to bond perforated cast metal splints to periodontally compromised teeth. A mechanical interlock was created as composite resin engaged these perforations and sustained the cast splint to acid-etched enamel. Howe adapted this design for replacement of anterior teeth by adding porcelain to a metal ceramic framework and then bonding the framework to abutments without tooth preparations. The advantages of these procedures were their conservative nature, esthetics, and ease of rebonding after dislodgment. Livaditis and Thompson adapted the procedure proposed by Tanaka of corrosion-pitting the bonding surface of a base metal alloy. They increased the surface area to be bonded, eliminated the perforations to improve rigidity of the framework, and described tooth preparation modifications of the abutments. They suggested an occlusal rest, establishment of guide planes through axial reduction, and a proximal extension to the facial surface to resist lingual displacement. Simonson, et al., based their anterior tooth preparation design on the configuration suggested by Livaditis which included a slight chamfer finish line plus reduction of the lingual surface to provide a thicker metal framework. Barrack introduced an inlay type tooth preparation for the occlusal rest plus shallow vertical proximal grooves, and Meiers used grooves as an esthetic alternative to proximal extensions. Clinical studies and surveys have identified specific variables involved with success and failure, while in vitro studies have evaluated framework designs, bonding agents, and methods for pitting the metal surface. This study evaluated resistance of RBFPDs to dislodgment of different tooth preparation designs.

Tooth colour change with Ozicure Oxygen Activator: a comparative in vitro tooth bleaching study.

PubMed

Grundlingh, A A; Grossman, E S; Witcomb, M J

2012-08-01

This in vitro study compared a new tooth bleaching product, Ozicure Oxygen Activator (O3, RSA) with Opalescence Quick (Ultradent, USA) using a randomised block design to assess tooth colour change. Colour change, stability and relapse in canine, incisor and premolar teeth was assessed following three bleach treatments and subsequent tooth colour assessment. Ninety nine teeth (canines, incisors and premolars), which were caries free, had no surface defects and were within the colour range 1M2 and 5M3 were selected. Teeth were randomly divided into the three experimental groups: Opalescence Quick, Ozicure Oxygen Activator and control. The three experimental groups received three treatments of one hour each over three consecutive days. Tooth colour was assessed using the Vitapan 3D Master Tooth Guide (VITA, Germany). A General Linear Models test for analysis of variance for a fractional design with significance set at P < 0.05 was used to test for significance. Both bleaching methods significantly lightened the teeth (P < 0.0001). Tooth colour change was mainly after the first hour of tooth bleaching. The tooth type was significant in tooth colour change (P = 0.0416). Tooth colour relapse and resistance to colour change were observed. Ozicure Oxygen Activator bleached teeth in a manner and to an extent similar to Opalescence Quick.

Mean annual attachment, bone level, and tooth loss: A systematic review.

PubMed

Needleman, Ian; Garcia, Raul; Gkranias, Nikos; Kirkwood, Keith L; Kocher, Thomas; Iorio, Anna Di; Moreno, Federico; Petrie, Aviva

2018-06-01

Rate of progression of periodontitis has been used to inform the design of classifications of periodontal diseases. However, the evidence underpinning this topic is unclear and no systematic review has yet been conducted. The focused question for this systematic review was: in adults, what is the progression of periodontitis in terms of clinical attachment loss, radiographic bone loss, and tooth loss? Highly sensitive electronic search was conducted for published data in MEDLINE, EMBASE, LILACS, and unpublished grey literature in OpenGrey up to February 2016. Reference lists of retrieved studies for full-text screening and reviews were hand-searched for potentially eligible studies. Prospective, longitudinal observational studies with follow-up of at least 12 months and presenting data on the primary outcome, change in clinical attachment level, in adults (age ≥18 years). Secondary outcomes, tooth loss and bone level change, were only assessed in studies reporting the primary outcome. Studies investigating specific disease populations or only on treated periodontitis patients were excluded. Risk of bias and methodology were assessed using the Newcastle-Ottawa Scale with two additional questions on security of outcome assessment. Studies were pooled by abstracting or estimating mean annual attachment or bone level change and annual tooth loss. Random effects meta-analysis was conducted with investigation of effect of potential modifiers where possible. A total 11,482 records were screened for eligibility; 33 publications of 16 original studies reporting on more than 8,600 participants were finally included as eligible for the review. The studies represented populations from both developing and developed economies. Mean annual attachment loss was 0.1 mm per year (95% CI 0.068, 0.132; I 2  = 99%) and mean annual tooth loss was 0.2 teeth per year (95% CI 0.10, 0.33; I 2  = 94%). Observational analysis of highest and lowest mean attachment change quintiles suggested substantial differences between groups with minimal annual change in the lowest quintile and an average deterioration of 0.45 mm mean attachment loss per year in the highest group. This value increased to 0.6 mm per year with periodontitis alone. There was surprisingly little effect of age or gender on attachment level change. Geographic location, however, was associated with more than three times higher mean annual attachment loss in Sri Lanka and China (0.20 mm, 95% CI 0.15, 0.27; I 2  = 83%) vs North America and Europe (0.056 mm, 95% CI 0.025, 0.087; I 2  = 99%) P < 0.001. There were a limited number of studies (N = 16), high variability of design in key study components (sampling frames, included ages, data analyses), and high statistical heterogeneity that could not be explained. Within the limitations of the research, the data show that mean annual attachment level change varies considerably both within and between populations. Overall, the evidence does not support or refute the differentiation between forms of periodontal diseases based upon progression of attachment level change. © 2018 American Academy of Periodontology and European Federation of Periodontology.

A probability distribution model of tooth pits for evaluating time-varying mesh stiffness of pitting gears

NASA Astrophysics Data System (ADS)

Lei, Yaguo; Liu, Zongyao; Wang, Delong; Yang, Xiao; Liu, Huan; Lin, Jing

2018-06-01

Tooth damage often causes a reduction in gear mesh stiffness. Thus time-varying mesh stiffness (TVMS) can be treated as an indication of gear health conditions. This study is devoted to investigating the mesh stiffness variations of a pair of external spur gears with tooth pitting, and proposes a new model for describing tooth pitting based on probability distribution. In the model, considering the appearance and development process of tooth pitting, we model the pitting on the surface of spur gear teeth as a series of pits with a uniform distribution in the direction of tooth width and a normal distribution in the direction of tooth height, respectively. In addition, four pitting degrees, from no pitting to severe pitting, are modeled. Finally, influences of tooth pitting on TVMS are analyzed in details and the proposed model is validated by comparing with a finite element model. The comparison results show that the proposed model is effective for the TVMS evaluations of pitting gears.

Dual lead-crowning for helical gears with anti-twist tooth flanks on the internal gear honing machine

NASA Astrophysics Data System (ADS)

Tran, Van-Quyet; Wu, Yu-Ren

2017-12-01

For some specific purposes, a helical gear with wide face-width is applied for meshing with two other gears simultaneously, such as the idle pinions in the vehicle differential. However, due to the fact of gear deformation, the tooth edge contact and stress concentration might occur. Single lead-crowning is no more suitable for such a case to get the appropriate position of contact pattern and improve the load distribution on tooth surfaces. Therefore, a novel *Email: method is proposed in this paper to achieve the wide-face-width helical gears with the dual lead-crowned and the anti-twisted tooth surfaces by controlling the swivel angle and the rotation angle of the honing wheel respectively on an internal gear honing machine. Numerical examples are practiced to illustrate and verified the merits of the proposed method.

Tooth surface treatment strategies for adhesive cementation

PubMed Central

2017-01-01

PURPOSE The aim of this study was to evaluate the effect of tooth surface pre-treatment steps on shear bond strength, which is essential for understanding the adhesive cementation process. MATERIALS AND METHODS Shear bond strengths of different cements with various tooth surface treatments (none, etching, priming, or etching and priming) on enamel and dentin of human teeth were measured using the Swiss shear test design. Three adhesives (Permaflo DC, Panavia F 2.0, and Panavia V5) and one self-adhesive cement (Panavia SA plus) were included in this study. The interface of the cement and the tooth surface with the different pre-treatments was analyzed using SEM. pH values of the cements and primers were measured. RESULTS The highest bond strength values for all cements were achieved with etching and primer on enamel (25.6 ± 5.3 - 32.3 ± 10.4 MPa). On dentin, etching and priming produced the highest bond strength values for all cements (8.6 ± 2.9 - 11.7 ± 3.5 MPa) except for Panavia V5, which achieved significantly higher bond strengths when pre-treated with primer only (15.3 ± 4.1 MPa). Shear bond strength values were correlated with the micro-retentive surface topography of enamel and the tag length on dentin except for Panavia V5, which revealed the highest bond strength with primer application only without etching, resulting in short but sturdy tags. CONCLUSION The highest bond strength can be achieved for Panavia F 2.0, Permaflo DC, and Panavia SA plus when the tooth substrate is previously etched and the respective primer is applied. The new cement Panavia V5 displayed low technique-sensitivity and attained significantly higher adhesion of all tested cements to dentin when only primer was applied. PMID:28435616

Tooth brushing inhibits oral bacteria in dogs.

PubMed

Watanabe, Kazuhiro; Hayashi, Kotaro; Kijima, Saku; Nonaka, Chie; Yamazoe, Kazuaki

2015-10-01

In this study, scaling, polishing and daily tooth brushing were performed in 20 beagle dogs, and the number of oral bacteria was determined using a bacterial counter. The dogs were randomized into the scaling (S), scaling + polishing (SP), scaling + tooth daily brushing (SB) and scaling + polishing + tooth daily brushing (SPB) groups. Samples were collected from the buccal surface of the maxillary fourth premolars of the dogs immediately after scaling and every week thereafter from weeks 1 to 8. Throughout the study, the number of bacteria was significantly lower in the SB and SPB groups compared with the S group. The findings suggest that daily tooth brushing inhibited oral bacterial growth in the dogs.

[The design of removable appliances for tooth movement and tooth migration].

PubMed

Voss, H

1989-06-01

Removable/functional appliance therapy can still be further expanded and developed. Retentive elements in the anterior region increase anchorage. Thereby, active forces can be utilised without anchorage loss. Functional appliances are indicated following extraction, to maximise on tooth migration. In first molar extraction cases, treatment with activators is relatively straightforward. When considering premolar extraction cases with possible need for extraction later of the third molars as well, then one should consider extraction of the first permanent molars. With correct use of the appliance, it is possible to optimally align the second molar teeth as well as favourably influencing the soft tissue profile.

Soft drink, software and softening of teeth - a case report of tooth wear in the mixed dentition due to a combination of dental erosion and attrition.

PubMed

Gambon, D L; Brand, H S; Nieuw Amerongen, A V

2010-10-21

This case report describes a 9-year-old boy with severe tooth wear as a result of drinking a single glass of soft drink per day. This soft drink was consumed over a period of one to two hours, while he was gaming intensively on his computer. As a result, a deep bite, enamel cupping, sensitivity of primary teeth and loss of fillings occurred. Therefore, dentists should be aware that in patients who are gaming intensively, the erosive potential of soft drinks can be potentiated by mechanical forces leading to excessive tooth wear.

Management of long span partially edentulous maxilla with fixed removable denture prosthesis

PubMed Central

Jeyavalan, Mahilan I.; Narasimman, M.; Venkatakrishnan, C. J.; Philip, Jacob M.

2012-01-01

Restoration of a long span partially edentulous maxilla with tooth supported prosthesis is challenging because of inherent anatomic limitations and unfavourable biomechanics present after the loss of teeth. A tooth supported fixed-removable prosthesis is a treatment option for restoration of such long span partially edentulous maxillary arches. This prosthesis meets the requirements for esthetics, phonetics, comfort, and hygiene, as well as favourable biomechanical stress distribution to the remaining natural tooth abutments. This article presents a procedure for fabrication of a fixed-removable prosthesis that has cement-retained custom cast bar metal substructure and a ball attachment retained removable superstructure prosthesis. PMID:23293488

Management of long span partially edentulous maxilla with fixed removable denture prosthesis.

PubMed

Jeyavalan, Mahilan I; Narasimman, M; Venkatakrishnan, C J; Philip, Jacob M

2012-07-01

Restoration of a long span partially edentulous maxilla with tooth supported prosthesis is challenging because of inherent anatomic limitations and unfavourable biomechanics present after the loss of teeth. A tooth supported fixed-removable prosthesis is a treatment option for restoration of such long span partially edentulous maxillary arches. This prosthesis meets the requirements for esthetics, phonetics, comfort, and hygiene, as well as favourable biomechanical stress distribution to the remaining natural tooth abutments. This article presents a procedure for fabrication of a fixed-removable prosthesis that has cement-retained custom cast bar metal substructure and a ball attachment retained removable superstructure prosthesis.

c-Jun activation in Schwann cells protects against loss of sensory axons in inherited neuropathy

PubMed Central

Hantke, Janina; Carty, Lucy; Wagstaff, Laura J.; Turmaine, Mark; Wilton, Daniel K.; Quintes, Susanne; Koltzenburg, Martin; Baas, Frank; Mirsky, Rhona

2014-01-01

Charcot–Marie–Tooth disease type 1A is the most frequent inherited peripheral neuropathy. It is generally due to heterozygous inheritance of a partial chromosomal duplication resulting in over-expression of PMP22. A key feature of Charcot–Marie–Tooth disease type 1A is secondary death of axons. Prevention of axonal loss is therefore an important target of clinical intervention. We have previously identified a signalling mechanism that promotes axon survival and prevents neuron death in mechanically injured peripheral nerves. This work suggested that Schwann cells respond to injury by activating/enhancing trophic support for axons through a mechanism that depends on upregulation of the transcription factor c-Jun in Schwann cells, resulting in the sparing of axons that would otherwise die. As c-Jun orchestrates Schwann cell support for distressed neurons after mechanical injury, we have now asked: do Schwann cells also activate a c-Jun dependent neuron-supportive programme in inherited demyelinating disease? We tested this by using the C3 mouse model of Charcot–Marie–Tooth disease type 1A. In line with our previous findings in humans with Charcot–Marie–Tooth disease type 1A, we found that Schwann cell c-Jun was elevated in (uninjured) nerves of C3 mice. We determined the impact of this c-Jun activation by comparing C3 mice with double mutant mice, namely C3 mice in which c-Jun had been conditionally inactivated in Schwann cells (C3/Schwann cell-c-Jun−/− mice), using sensory-motor tests and electrophysiological measurements, and by counting axons in proximal and distal nerves. The results indicate that c-Jun elevation in the Schwann cells of C3 nerves serves to prevent loss of myelinated sensory axons, particularly in distal nerves, improve behavioural symptoms, and preserve F-wave persistence. This suggests that Schwann cells have two contrasting functions in Charcot–Marie–Tooth disease type 1A: on the one hand they are the genetic source of the disease, on the other, they respond to it by mounting a c-Jun-dependent response that significantly reduces its impact. Because axonal death is a central feature of much nerve pathology it will be important to establish whether an axon-supportive Schwann cell response also takes place in other conditions. Amplification of this axon-supportive mechanism constitutes a novel target for clinical intervention that might be useful in Charcot–Marie–Tooth disease type 1A and other neuropathies that involve axon loss. PMID:25216747

Comparing two quantitative methods for studying remineralization of artificial caries.

PubMed

Lo, E C M; Zhi, Q H; Itthagarun, A

2010-04-01

To compare the detection of changes before and after remineralization of artificial enamel and dentin caries by microCT scanning, polarized light microscopy (PLM) and transverse microradiography (TMR). Fourteen extracted premolars were cut into tooth blocks and painted with an acid-resistant varnish leaving one enamel and one dentin surface exposed. The tooth blocks were immersed into demineralizing solution for 4 days to produce artificial caries-like lesions and scanned by microCT. Then the 14 tooth blocks were randomly allocated into two groups. Seven tooth blocks in Group I were cut longitudinally through the exposed surface into 100-150 microm thick sections and microradiographs were taken. The other seven tooth blocks in Group II were left intact. All the tooth blocks and sections were then immersed into remineralizing solution for 5 days. PLM and TMR of the tooth sections in Group I were taken again. Depth of the lesion on the TMR was measured. Tooth blocks in Group II were scanned by microCT. Mean lesion depth in Group I reduced by 13.0% and 8.2% after remineralization for enamel and dentin, respectively (paired t-test, P<0.001). In Group II, linear attenuation coefficient (LAC) of the region of interest (ROI) increased by 11.1% and 23.8% after remineralization for enamel and dentin lesions, respectively (paired t-test, P<0.001). Both microCT and microradiography are able to detect a change of similar magnitude in the artificial caries lesions after remineralization. MicroCT may be used to substitute TMR and PLM in in vitro studies about caries. Copyright 2010 Elsevier Ltd. All rights reserved.

Severity of MIH findings at tooth surface level among German school children.

PubMed

Petrou, M A; Giraki, M; Bissar, A-R; Wempe, C; Schäfer, M; Schiffner, U; Beikler, T; Schulte, A G; Splieth, C H

2015-06-01

This study was to investigate the distribution and clinical characteristics of teeth diagnosed with MIH at surface and defect type level in a cohort of German children. The study cohort included 242 children diagnosed with MIH which had been recorded during the compulsory dental school examinations of 20 German primary schools. The subjects had been enrolled by cluster sampling. All children attended the second to fourth grade (age 7-10 years, mean 8.1 ± 0.8). The children were examined by five calibrated examiners (kappa = 0.9) after tooth brushing. The recording comprised teeth, surfaces, type and severity of MIH defects and was conducted using a portable light, mirrors and cotton rolls. MIH was registered according to the EAPD criteria. Defects <1 mm were not recorded. Statistical analysis included descriptive statistics and Spearman's correlation. Most affected teeth were first permanent molars (71.4 %) followed by the maxillary central incisors (15.6 %). The most common defects were demarcated opacities (82.2 %), while the remaining 17.8 % of the affected teeth exhibited severe enamel defects. The most frequently affected surface in molars was the occlusal surface (72.4 %); in incisors, it was the buccal surface (73.5 %). There were no atypical restorations in the affected incisors. Different types of MIH defects at various surfaces of the same tooth were common. The number of affected tooth surfaces was positively correlated with the severity of MIH at child (p < 0.001). The study demonstrates severe enamel defects involving in almost one-fifth of all MIH teeth. The knowledge of the intra-oral distribution and severity of MIH findings at the enamel surface level is important for assessing the treatment needs.

Minimization of deviations of gear real tooth surfaces determined by coordinate measurements

NASA Technical Reports Server (NTRS)

Litvin, F. L.; Kuan, C.; Wang, J.-C.; Handschuh, R. F.; Masseth, J.; Maruyama, N.

1992-01-01

The deviations of a gear's real tooth surface from the theoretical surface are determined by coordinate measurements at the grid of the surface. A method was developed to transform the deviations from Cartesian coordinates to those along the normal at the measurement locations. Equations are derived that relate the first order deviations with the adjustment to the manufacturing machine-tool settings. The deviations of the entire surface are minimized. The minimization is achieved by application of the least-square method for an overdetermined system of linear equations. The proposed method is illustrated with a numerical example for hypoid gear and pinion.

16-Year follow-up of an avulsed maxillary central incisor after replantation following 10-h storage: An unusual case.

PubMed

Kırzıoğlu, Zuhal; Erken Güngör, Özge; Erdoğan, Yıldırım

2017-07-01

Tooth avulsion is a type of dental injury defined as the complete displacement of a tooth out of the alveolar socket, and the lack of prompt treatment measures can result in the loss of function, poor quality of life, and psychological and social problems. However, several factors may not permit the immediate replantation of an avulsed tooth; therefore, delayed replantation has emerged as an alternative to meet the esthetic, functional, and psychological demands of patients. Here it was described that the successful replantation of an avulsed maxillary central incisor in a 9-year-old boy who presented at the clinic with the tooth stored in unfavorable conditions as dry and then in olive oil-milk mixture almost 10 h after the event. The tooth has remained in its socket healthy for 16 years after treatment. The patient was satisfied with both esthetics and function. © 2017 Special Care Dentistry Association and Wiley Periodicals, Inc.

Tooth Discoloration in Patients With Neonatal Diabetes After Transfer Onto Glibenclamide

PubMed Central

Kumaraguru, Janani; Flanagan, Sarah E.; Greeley, Siri Atma W.; Nuboer, Roos; Støy, Julie; Philipson, Louis H.; Hattersley, Andrew T.; Rubio-Cabezas, Oscar

2009-01-01

OBJECTIVE To assess if tooth discoloration is a novel side effect of sulfonylurea therapy in patients with permanent neonatal diabetes due to mutations in KCNJ11. RESEARCH DESIGN AND METHODS A total of 67 patients with a known KCNJ11 mutation who had been successfully transferred from insulin injections onto oral sulfonylureas were contacted and asked about the development of tooth discoloration after transfer. RESULTS Altered tooth appearance was identified in 5 of the 67 patients. This was variable in severity, ranging from mild discoloration/staining (n = 4) to loss of enamel (n = 1) and was only seen in patients taking glibenclamide (glyburide). CONCLUSIONS These previously unreported side effects may relate to the developing tooth and/or to the high local concentrations in the children who frequently chewed glibenclamide tablets or took it as a concentrated solution. Given the multiple benefits of sulfonylurea treatment for patients with activating KCNJ11 mutations, this association warrants further investigation but should not preclude such treatment. PMID:19435956

Dental Space Deficiency Syndrome: An Anthropological Perspective.

PubMed

Richman, Colin S

2017-03-01

A new syndrome in dentistry, the dental space deficiency syndrome is proposed in this article. Signs and symptoms of this entity may include one or more of the following clinical dental features: tooth crowding, gingival recession, tooth impactions, rapid resorption of facial alveolar bony plates following premature tooth loss, dentally oriented sleep disorders, extended orthodontic treatment time, and malocclusion relapse following orthodontic therapy. These oral conditions, individually or collectively, seem to be associated with both genetic and functional factors. From an anthropological-functional perspective, the human jaws (basal bone and/or alveolar bone) have been shrinking. This results in a three-dimensional discrepancy between jawbone and tooth volumes, which are genetically determined. Consequently, the reduced volume of alveolar bone is not adequately able to accommodate the associated genetically determined dentition in functional and esthetic harmony. This paper describes the common etiology for the conditions listed above, namely the discrepancy between alveolar bone volume (essentially determined by functionality), and associated tooth volume (essentially determined by genetics), when considered in a three-dimensional perspective.

Massive Losses of Taste Receptor Genes in Toothed and Baleen Whales

PubMed Central

Feng, Ping; Zheng, Jinsong; Rossiter, Stephen J.; Wang, Ding; Zhao, Huabin

2014-01-01

Taste receptor genes are functionally important in animals, with a surprising exception in the bottlenose dolphin, which shows extensive losses of sweet, umami, and bitter taste receptor genes. To examine the generality of taste gene loss, we examined seven toothed whales and five baleen whales and sequenced the complete repertoire of three sweet/umami (T1Rs) and ten bitter (T2Rs) taste receptor genes. We found all amplified T1Rs and T2Rs to be pseudogenes in all 12 whales, with a shared premature stop codon in 10 of the 13 genes, which demonstrated massive losses of taste receptor genes in the common ancestor of whales. Furthermore, we analyzed three genome sequences from two toothed whales and one baleen whale and found that the sour taste marker gene Pkd2l1 is a pseudogene, whereas the candidate salty taste receptor genes are intact and putatively functional. Additionally, we examined three genes that are responsible for taste signal transduction and found the relaxation of functional constraints on taste signaling pathways along the ancestral branch leading to whales. Together, our results strongly suggest extensive losses of sweet, umami, bitter, and sour tastes in whales, and the relaxation of taste function most likely arose in the common ancestor of whales between 36 and 53 Ma. Therefore, whales represent the first animal group to lack four of five primary tastes, probably driven by the marine environment with high concentration of sodium, the feeding behavior of swallowing prey whole, and the dietary switch from plants to meat in the whale ancestor. PMID:24803572

Modification of tooth and enamel characteristics following the Er,Cr:YSGG laser treatment

NASA Astrophysics Data System (ADS)

Suhaimi, Fatanah M.; Aziz, N. Afifah; Jaafar, M. S.; Azizan, Nur Syazana; Zali, Nurulakma; Razak, N. A. Abd

2016-12-01

Lasers have been widely used in the dental field to treat a number of applications in dentistry. The main objective of this study is to analyse the modification of tooth composition following the Er,Cr:YSGG laser procedure. In this study, human premolar teeth were collected and prepared. The samples were sectioned and molded. 3M Unitek Transbond™ Plus Self Etching Primer adhesive materials were applied to the tooth surface. Er,Cr:YSGG laser with a wavelength of 2790 nm was used in this study to remove the adhesive materials on the enamel surface. The irradiation process was done with four different output powers that are 0.25, 0.5, 0.75, and 1.0 W. The change of tooth characteristics was analysed by observing the morphology of the enamel surface and the elemental composition usinga Field Emission Scanning Electron Microscope (FESEM) and Electron Dispersive X-ray Spectrometer (EDX). Calcium (Ca), phosphorus (P), sodium (Na), oxygen (O), and carbon (C) were the elementsidentified by EDX in the samples. Additionally, oxygen was the most abundant element found in the sample. The level of oxygen composition decreased after laser irradiation while the carbon element increased. Another element, calcium was found to be decreasing due to the process of applying adhesive materials on the enamel surface.

Turbine interstage seal with self-balancing capability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mills, Jacob A; Jones, Russell B; Sexton, Thomas D

An interstage seal for a turbine of a gas turbine engine, the interstage seal having a seal carrier with an axial extending seal tooth movable with a stator of the engine, and a rotor with a seal surface that forms the interstage seal with the seal tooth, where a magnetic force produced by two magnets and a gas force produced by a gas pressure acting on the seal carrier forms a balancing force to maintain a close clearance of the seal without the seal tooth contacting the rotor seal surfaces during engine operation. In other embodiments, two pairs of magnetsmore » produce first and second magnetic forces that balance the seal in the engine.« less

Surface Fatigue Resistance with Induction Hardening

NASA Technical Reports Server (NTRS)

Townsend, Dennis; Turza, Alan; Chapman, Mike

1996-01-01

Induction hardening has been used for some years to harden the surface and improve the strength and service life of gears and other components. Many applications that employ induction hardening require a relatively long time to finish the hardening process and controlling the hardness of the surface layer and its depth often was a problem. Other surface hardening methods, ie., carbonizing, take a very long time and tend to cause deformations of the toothing, whose elimination requires supplementary finishing work. In double-frequency induction hardening, one uses a low frequency for the preheating of the toothed wheel and a much higher frequency for the purpose of rapidly heating the surface by way of surface hardening.

Analysis of dental abfractions by optical coherence tomography

NASA Astrophysics Data System (ADS)

Demjan, Enikö; Mărcăuţeanu, Corina; Bratu, Dorin; Sinescu, Cosmin; Negruţiu, Meda; Ionita, Ciprian; Topală, Florin; Hughes, Michael; Bradu, Adrian; Dobre, George; Podoleanu, Adrian Gh.

2010-02-01

Aim and objectives. Abfraction is the pathological loss of cervical hard tooth substance caused by biomechanical overload. High horizontal occlusal forces result in large stress concentrations in the cervical region of the teeth. These stresses may be high enough to cause microfractures in the dental hard tissues, eventually resulting in the loss of cervical enamel and dentin. The present study proposes the microstructural characterization of these cervical lesions by en face optical coherence tomography (eFOCT). Material and methods: 31 extracted bicuspids were investigated using eFOCT. 24 teeth derived from patients with active bruxism and occlusal interferences; they presented deep buccal abfractions and variable degrees of occlusal pathological attrition. The other 7 bicuspids were not exposed to occlusal overload and had a normal morphology of the dental crowns. The dental samples were investigated using an eFOCT system operating at 1300 nm (B-scan at 1 Hz and C-scan mode at 2 Hz). The system has a lateral resolution better than 5 μm and a depth resolution of 9 μm in tissue. OCT images were further compared with micro - computer tomography images. Results. The eFOCT investigation of bicuspids with a normal morphology revealed a homogeneous structure of the buccal cervical enamel. The C-scan and B-scan images obtained from the occlusal overloaded bicuspids visualized the wedge-shaped loss of cervical enamel and damage in the microstructure of the underlaying dentin. The high occlusal forces produced a characteristic pattern of large cracks, which reached the tooth surface. Conclusions: eFOCT is a promising imaging method for dental abfractions and it may offer some insight on the etiological mechanism of these noncarious cervical lesions.

A numerical simulation of tooth movement by wire bending.

PubMed

Kojima, Yukio; Fukui, Hisao

2006-10-01

In orthodontic treatment, wires are bent and attached to teeth to move them via elastic recovery. To predict how a tooth will move, the initial force system produced from the wire is calculated. However, the initial force system changes as the tooth moves and may not be used to predict the final tooth position. The purpose of this study was to develop a comprehensive mechanical, 3-dimensional, numerical model for predicting tooth movement. Tooth movements produced by wire bending were simulated numerically. The teeth moved as a result of bone remodeling, which occurs in proportion to stress in the periodontal ligament. With an off-center bend, a tooth near the bending position was subjected to a large moment and tipped more noticeably than the other teeth. Also, a tooth far from the bending position moved slightly in the mesial or the distal direction. With the center V-bend, when the second molar was added as an anchor tooth, the tipping angle and the intrusion of the canine increased, and movement of the first molar was prevented. When a wire with an inverse curve of Spee was placed in the mandibular arch, the calculated tendency of vertical tooth movements was the same as the measured result. In these tooth movements, the initial force system changed as the teeth moved. Tooth movement was influenced by the size of the root surface area. Tooth movements produced by wire bending could be estimated. It was difficult to predict final tooth positions from the initial force system.

The junctional epithelium originates from the odontogenic epithelium of an erupted tooth.

PubMed

Yajima-Himuro, Sara; Oshima, Masamitsu; Yamamoto, Gou; Ogawa, Miho; Furuya, Madoka; Tanaka, Junichi; Nishii, Kousuke; Mishima, Kenji; Tachikawa, Tetsuhiko; Tsuji, Takashi; Yamamoto, Matsuo

2014-05-02

The junctional epithelium (JE) is an epithelial component that is directly attached to the tooth surface and has a protective function against periodontal diseases. In this study, we determined the origin of the JE using a bioengineered tooth technique. We transplanted the bioengineered tooth germ into the alveolar bone with an epithelial component that expressed green fluorescence protein. The reduced enamel epithelium from the bioengineered tooth fused with the oral epithelium, and the JE was apparently formed around the bioengineered tooth 50 days after transplantation. Importantly, the JE exhibited green fluorescence for at least 140 days after transplantation, suggesting that the JE was not replaced by oral epithelium. Therefore, our results demonstrated that the origin of the JE was the odontogenic epithelium, and odontogenic epithelium-derived JE was maintained for a relatively long period.

The junctional epithelium originates from the odontogenic epithelium of an erupted tooth

PubMed Central

Yajima-Himuro, Sara; Oshima, Masamitsu; Yamamoto, Gou; Ogawa, Miho; Furuya, Madoka; Tanaka, Junichi; Nishii, Kousuke; Mishima, Kenji; Tachikawa, Tetsuhiko; Tsuji, Takashi; Yamamoto, Matsuo

2014-01-01

The junctional epithelium (JE) is an epithelial component that is directly attached to the tooth surface and has a protective function against periodontal diseases. In this study, we determined the origin of the JE using a bioengineered tooth technique. We transplanted the bioengineered tooth germ into the alveolar bone with an epithelial component that expressed green fluorescence protein. The reduced enamel epithelium from the bioengineered tooth fused with the oral epithelium, and the JE was apparently formed around the bioengineered tooth 50 days after transplantation. Importantly, the JE exhibited green fluorescence for at least 140 days after transplantation, suggesting that the JE was not replaced by oral epithelium. Therefore, our results demonstrated that the origin of the JE was the odontogenic epithelium, and odontogenic epithelium-derived JE was maintained for a relatively long period. PMID:24785116

The genetic basis of modularity in the development and evolution of the vertebrate dentition.

PubMed Central

Stock, D W

2001-01-01

The construction of organisms from units that develop under semi-autonomous genetic control (modules) has been proposed to be an important component of their ability to undergo adaptive phenotypic evolution. The organization of the vertebrate dentition as a system of repeated parts provides an opportunity to study the extent to which phenotypic modules, identified by their evolutionary independence from other such units, are related to modularity in the genetic control of development. The evolutionary history of vertebrates provides numerous examples of both correlated and independent evolution of groups of teeth. The dentition itself appears to be a module of the dermal exoskeleton, from which it has long been under independent genetic control. Region-specific tooth loss has been a common trend in vertebrate evolution. Novel deployment of teeth and reacquisition of lost teeth have also occurred, although less frequently. Tooth shape differences within the dentition may be discontinuous (referred to as heterodonty) or graded. The occurrence of homeotic changes in tooth shape provides evidence for the decoupling of tooth shape and location in the course of evolution. Potential mechanisms for region-specific evolutionary tooth loss are suggested by a number of mouse gene knockouts and human genetic dental anomalies, as well as a comparison between fully-developed and rudimentary teeth in the dentition of rodents. These mechanisms include loss of a tooth-type-specific initiation signal, alterations of the relative strength of inductive and inhibitory signals acting at the time of tooth initiation and the overall reduction in levels of proteins required for the development of all teeth. Ectopic expression of tooth initiation signals provides a potential mechanism for the novel deployment or reacquisition of teeth; a single instance is known of a gene whose ectopic expression in transgenic mice can lead to ectopic teeth. Differences in shape between incisor and molar teeth in the mouse have been proposed to be controlled by the region-specific expression of signalling molecules in the oral epithelium. These molecules induce the expression of transcription factors in the underlying jaw mesenchyme that may act as selectors of tooth type. It is speculated that shifts in the expression domains of the epithelial signalling molecules might be responsible for homeotic changes in tooth shape. The observation that these molecules are regionally restricted in the chicken, whose ancestors were not heterodont, suggests that mammalian heterodonty may have evolved through the use of patterning mechanisms already acting on skeletal elements of the jaws. In general, genetic and morphological approaches identify similar types of modules in the dentition, but the data are not yet sufficient to identify exact correspondences. It is speculated that modularity may be achieved by gene expression differences between teeth or by differences in the time of their development, causing mutations to have cumulative effects on later-developing teeth. The mammalian dentition, for which virtually all of the available developmental genetic data have been collected, represents a small subset of the dental diversity present in vertebrates as a whole. In particular, teleost fishes may have a much more extensive dentition. Extension of research on the genetic control of tooth development to this and other vertebrate groups has great potential to further the understanding of modularity in the dentition. PMID:11604128

The evaluation of MCI, MI, PMI and GT on both genders with different age and dental status.

PubMed

Bozdag, G; Sener, S

2015-01-01

The aim of this study was to measure the mandibular cortical index (MCI), mental index (MI), panoramic mandibular index (PMI) and cortical bone thickness in the zone of the gonial angle (GT) in panoramic radiographies from a large sample of males and females and to determine how they relate to patients' age, gender and dental status. 910 panoramic radiographs were obtained and grouped into age, dental status and gender. The MCI, MI, PMI and GT were analysed. Remarkable differences were observed for MCI and GT regarding gender, age groups and dental status on both sides (p < 0.05). While age and dental status had an effect on the MI and PMI in females, dental status had an effect on the MI and PMI in males (p < 0.05). Also, gender had an effect on the MI and PMI (p < 0.05). The effects of age and tooth loss are different in females and males. In females, the harmful effects of tooth loss and age are more prominent according to the PMI and MI measurements. The effects of age and tooth loss in the GT and MCI measurements are similar, and these indices can be accepted as more reliable in studies including both genders.

The evaluation of MCI, MI, PMI and GT on both genders with different age and dental status

PubMed Central

Sener, S

2015-01-01

Objectives: The aim of this study was to measure the mandibular cortical index (MCI), mental index (MI), panoramic mandibular index (PMI) and cortical bone thickness in the zone of the gonial angle (GT) in panoramic radiographies from a large sample of males and females and to determine how they relate to patients' age, gender and dental status. Methods: 910 panoramic radiographs were obtained and grouped into age, dental status and gender. The MCI, MI, PMI and GT were analysed. Results: Remarkable differences were observed for MCI and GT regarding gender, age groups and dental status on both sides (p < 0.05). While age and dental status had an effect on the MI and PMI in females, dental status had an effect on the MI and PMI in males (p < 0.05). Also, gender had an effect on the MI and PMI (p < 0.05). Conclusions: The effects of age and tooth loss are different in females and males. In females, the harmful effects of tooth loss and age are more prominent according to the PMI and MI measurements. The effects of age and tooth loss in the GT and MCI measurements are similar, and these indices can be accepted as more reliable in studies including both genders. PMID:26133366

Comparison of destructive periodontal disease in blue iris mink to PCB 126-induced mandibular and maxillary squamous epithelial proliferation in natural dark mink.

PubMed

Ellick, Rachel M; Fitzgerald, Scott D; Link, Jane E; Bursian, Steven J

2013-01-01

Mink (Mustela vison) exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like chemicals have been reported to develop mandibular and maxillary squamous cell proliferation that results in the destruction of alveolar bone and eventual tooth loss. This jaw lesion has been reported in wild mink collected from areas contaminated with TCDD-like compounds and is a potential biomarker for exposure to these chemicals. The blue iris strain of domestic mink is prone to develop severe periodontal disease, which results in destruction of bone and tooth loss that is grossly similar to the lesion induced by exposure to TCDD-like chemicals. A histological assessment of jaws from blue iris mink and natural dark mink exposed to 3,3',4,4',5-pentachlorobiphenyl (PCB 126) was done to determine whether the oral lesions are similar. The jaw tissue from the blue iris mink had lesions indicative of lymphoplasmacytic gingivitis and osteomyelitis, caused by inflammation entering the dental sulcus, while the jaw tissue from the mink exposed to PCB 126 exhibited squamous epithelial proliferation. Therefore, it was determined that the tooth loss and bone destruction seen in these mink are of different origin despite the similarity of the gross clinical signs.

EVALUATION OF CLINICAL PERIODONTAL CONDITIONS IN SMOKERS AND NON-SMOKERS

PubMed Central

Luzzi, Lucinara Ignez Tavares; Greghi, Sebastião Luiz Aguiar; Passanezi, Euloir; Sant'ana, Adriana Campos Passanezi; Lauris, José Roberto Pereira; Cestari, Tânia Mary

2007-01-01

Given that tobacco smoking habit is a risk factor for periodontal diseases, the aim of this study was to compare clinical periodontal aspects between smokers and non-smokers. The clinical status were assessed in 55 patients, 29 smokers and 26 non-smokers, aged 30 to 50 years, with mean age of 40. The clinical parameters used were: probing depth (PD), plaque index (PI), gingival index (GI), clinical attachment level (CAL), gingival recession (GR) and gingival bleeding index (GBI) for arches (upper and lower) and teeth (anterior and posterior). Tooth loss was also evaluated in both groups. Multiple regression analysis showed: tendency of greater probing depth and clinical attachment level means for smokers; greater amount of plaque in smokers in all regions; greater gingival index means for non-smokers with clinical significance (p<0.05) in all regions. Although, without statistical significance, the analysis showed greater gingival bleeding index means almost always for non-smokers; similar gingival recession means in both groups and tendency of upper tooth loss in smokers and lower tooth loss in non-smokers. The findings of this study showed that clinical periodontal parameters may be different in smokers when compared to non-smokers and that masking of some periodontal signs can be a result of nicotine's vasoconstrictor effect. PMID:19089190

Prevalence of dental trauma and use of mouthguards in rugby union players.

PubMed

Ilia, E; Metcalfe, K; Heffernan, M

2014-12-01

There is a high prevalence of orofacial trauma in rugby union players. Mouthguards reduce complications following dental injuries, should dental injuries occur. The aim of this study was to investigate the prevalence of oral trauma and the significance of mouthguard use in adult amateur rugby union players in New South Wales, Australia. Questionnaires were distributed to players in rugby union clubs. It questioned players about their mouthguard use and orofacial trauma experience; the type of injury, complications, if a mouthguard was worn, where treatment was sought and outcome. The prevalence of orofacial trauma in rugby union players is 64.9%. The most common injury was laceration to intraoral and extraoral soft tissues at 44.5%. Of all orofacial injuries reported, 41.9% were to the dentition. Following dental injury, loss of the tooth was the most common complication (34.7%). 76.9% of players wore mouthguards. By wearing a mouthguard, the risk reduction for ongoing complications following dental injuries was 18.5% (p-value = 0.009). Of these, 10.4% (p-value = 0.45) represented loss of the tooth. Rates of orofacial trauma and complications in amateur rugby union players are high in Australia. Use of mouthguards results in significant risk reduction for complications following dental injuries, including loss of tooth. © 2014 Australian Dental Association.

Racial/ethnic variations in associations between socioeconomic factors and tooth loss.

PubMed

Jimenez, Monik; Dietrich, Thomas; Shih, Mei-Chiung; Li, Yi; Joshipura, Kaumudi J

2009-06-01

To compare the associations between socioeconomic factors and tooth loss among White, Black, and Mexican-American people. Analyses were conducted on 16,821 adults, using data from the National Health and Nutrition Examination Survey-III. Age- and multivariate-adjusted negative binomial regressions were used to explore the relation of socioeconomic factors, region of residence, gender, and foreign birth with the number of missing teeth. Effect modification by race/ethnicity was assessed by the inclusion of interaction terms. In multivariate-adjusted analyses, non-Hispanic White people with 9-12 years of education exhibited 71% higher mean number of missing teeth than those with >12 years of education [incidence rate ratio (IRR) = 1.71, 95% confidence interval (CI): 1.52-1.92]. Education was unrelated to the number of teeth among non-Hispanic Black people (IRR = 1.16; 95% CI: 1.00-1.35) or Mexican-Americans (IRR = 1.10, 95% CI: 0.93-1.31). The poorest White people exhibited 39% more missing teeth, on average, than the most affluent White people, but no association between poverty and number of teeth was observed among Black or Mexican-American people. The associations between socioeconomic factors and tooth loss vary across race/ethnicity. This suggests that the health benefits associated with high socioeconomic status are not equally shared across racial/ethnic groups.

Second-harmonic generation microscopy of tooth

NASA Astrophysics Data System (ADS)

Kao, Fu-Jen; Wang, Yung-Shun; Huang, Mao-Kuo; Huang, Sheng-Lung; Cheng, Ping C.

2000-07-01

In this study, we have developed a high performance microscopic system to perform second-harmonic (SH)imaging on a tooth. The high sensitivity of the system allows an acquisition rate of 300 seconds/frame with a resolution at 512x512 pixels. The surface SH signal generated from the tooth is also carefully verified through micro-spectroscopy, polarization rotation, and wavelength tuning. In this way, we can ensure the authenticity of the signal. The enamel that encapsulates the dentine is known to possess highly ordered structures. The anisotrophy of the structure is revealed in the microscopic SH images of the tooth sample.

Schoolchildren's tooth brushing characteristics and oral hygiene habits assessed with video-recorded sessions at school and a questionnaire.

PubMed

Martignon, Stefania; González, María Clara; Tellez, Marisol; Guzmán, Adriana; Quintero, Ingrid K; Sáenz, Viviana; Martínez, Miguel; Mora, Angelica; Espinosa, Luis Fernando; Castiblanco, Gina A

2012-01-01

Tooth brushing habits become established during the first years of childhood and last throughout lifetime. To assess tooth-brushing characteristics, the procedure was videotaped at school and a questionnaire on oral hygiene knowledge, attitudes and practices was completed. A total 146 5- to 8-year-old low-SES schoolchildren from Bogotá participated. The median total tooth brushing time was 115 sec (75% Q3-178 sec; 25% Q1-83 sec). The median time the toothbrush was in the child's mouth was 89 sec (75% Q3-145 sec; 25% Q1-65 sec). Most children brushed their maxillary (97%), mandibular (95%), anterior (96%) and posterior (81%) teeth. The surfaces most often brushed were the buccal-anterior-maxillary (96%) and mandibular (94%) surfaces. The amount of toothpaste dispensed was 2/3 of toothbrush head in 51% of children. Most children spat (93%), used the mirror (78%), and rinsed their mouth (72%). The majority (97%) was confident that the toothbrushing session was effective. The questionnaire revealed the following: none of the children brush their teeth at school; only 34% is supervised by an adult during the tooth brushing procedure, and only 30% brush twice a day. The study shows overall positive findings of tooth brushing while being observed, in terms of time and use of toothpaste. These results, together with the poor oral-health status and toothbrushing habits reported at home, highly recommend incorporating daily-supervised school-based tooth brushing sessions with fluoride toothpaste.

Design for high-power, single-lobe, grating-surface-emitting quantum cascade lasers enabled by plasmon-enhanced absorption of antisymmetric modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sigler, C.; Kirch, J. D.; Mawst, L. J.

2014-03-31

Resonant coupling of the transverse-magnetic polarized (guided) optical mode of a quantum-cascade laser (QCL) to the antisymmetric surface-plasmon modes of 2nd-order distributed-feedback (DFB) metal/semiconductor gratings results in strong antisymmetric-mode absorption. In turn, lasing in the symmetric mode, that is, surface emission in a single-lobe far-field beam pattern, is strongly favored over controllable ranges in grating duty cycle and tooth height. By using core-region characteristics of a published 4.6 μm-emitting QCL, grating-coupled surface-emitting (SE) QCLs are analyzed and optimized for highly efficient single-lobe operation. For infinite-length devices, it is found that when the antisymmetric mode is resonantly absorbed, the symmetric mode hasmore » negligible absorption loss (∼0.1 cm{sup −1}) while still being efficiently outcoupled, through the substrate, by the DFB grating. For finite-length devices, 2nd-order distributed Bragg reflector (DBR) gratings are used on both sides of the DFB grating to prevent uncontrolled reflections from cleaved facets. Equations for the threshold-current density and the differential quantum efficiency of SE DFB/DBR QCLs are derived. For 7 mm-long, 8.0 μm-wide, 4.6 μm-emitting devices, with an Ag/InP grating of ∼39% duty cycle, and ∼0.22 μm tooth height, threshold currents as low as 0.45 A are projected. Based on experimentally obtained internal efficiency values from high-performance QCLs, slope efficiencies as high as 3.4 W/A are projected; thus, offering a solution for watt-range, single-lobe CW operation from SE, mid-infrared QCLs.« less

Bite force measurements with hard and soft bite surfaces.

PubMed

Serra, C M; Manns, A E

2013-08-01

Bite force has been measured by different methods and over a wide variety of designs. In several instruments, the fact that bite surface has been manufactured with stiff materials might interfere in obtaining reliable data, by a more prompt activation of inhibitory reflex mechanisms. The purpose of this study was to compare the maximum voluntary bite force measured by a digital occlusal force gauge (GM10 Nagano Keiki, Japan) between different opponent teeth, employing semi-hard or soft bite surfaces. A sample of 34 young adults with complete natural dentition was studied. The original semi-hard bite surface was exchanged by a soft one, made of leather and rubber. Maximum voluntary bite force recordings were made for each tooth group and for both bite surfaces. Statistical analyses (Student's t-test) revealed significant differences, with higher scores while using the soft surface across sexes and tooth groups (P < 0·05). Differential activation of periodontal mechanoreceptors of a specific tooth group is mainly conditioned by the hardness of the bite surface; a soft surface induces greater activation of elevator musculature, while a hard one induces inhibition more promptly. Thus, soft bite surfaces are recommended for higher reliability in maximum voluntary bite force recordings. © 2013 John Wiley & Sons Ltd.

Saliva and Serum Protein Exchange at the Tooth Enamel Surface

PubMed Central

Heller, D.; Helmerhorst, E.J.; Oppenheim, F.G.

2016-01-01

The acquired enamel pellicle is an oral, fluid-derived protein layer that forms on the tooth surface. It is a biologically and clinically important integument that protects teeth against enamel demineralization, and abrasion. Tooth surfaces are exposed to different proteinaceous microenvironments depending on the enamel location. For instance, tooth surfaces close to the gingival sulcus contact serum proteins that emanate via this sulcus, which may impact pellicle composition locally. The aims of this study were to define the major salivary and serum components that adsorb to hydroxyapatite, to study competition among them, and to obtain preliminary evidence in an in vivo saliva/serum pellicle model. Hydroxyapatite powder was incubated with saliva and serum, and the proteins that adsorbed were identified by mass spectrometry. To study competition, saliva and serum proteins were labeled with CyDyes, mixed in various proportions, and incubated with hydroxyapatite. In vivo competition was assessed using a split-mouth design, with half the buccal tooth surfaces coated with serum and the other half with saliva. After exposure to the oral environment for 0 min, 30 min and 2 h, the pellicles were analyzed by SDS-PAGE. In pure saliva- or serum-derived pellicles, 82 and 84 proteins were identified, respectively. When present concomitantly, salivary protein adsorbers effectively competed with serum protein adsorbers for the hydroxyapatite surface. Specifically, acidic proline-rich protein, cystatin, statherin and protein S100-A9 proteins competed off apolipoproteins, complement C4-A, haptoglobin, transthyretin and serotransferrin. In vivo evidence further supported the replacement of serum proteins by salivary proteins. In conclusion, although significant numbers of serum proteins emanate from the gingival sulcus, their ability to participate in dental pellicle formation is likely reduced in the presence of strong salivary protein adsorbers. The functional properties of the acquired enamel pellicle will therefore be mostly dictated by the salivary component. PMID:27879420

Family history and oral health: findings from the Dunedin Study

PubMed Central

Shearer, Dara M; Thomson, W. Murray; Caspi, Avshalom; Moffitt, Terrie E; Broadbent, Jonathan M; Poulton, Richie

2011-01-01

Context The effects of the oral health status of one generation on that of the next within families are unclear. Objective To determine whether parental oral health history is a risk factor for oral disease. Methods Oral examination and interview data were collected during the age-32 assessments in the Dunedin Study. Parental data were also collected on this occasion. The sample was divided into two familial-risk groups for caries/tooth loss (high risk and low risk) based on parents’ self-reported history of tooth loss at the age-32 assessment interview. Main outcome measures Probands’ dental caries and tooth loss status at age 32, together with lifelong dental caries trajectory (age 5–32). Results Caries/tooth-loss risk analysis was conducted for 640 proband-parents groups. Referent groups were the low-familial-risk groups. After controlling for confounding factors (sex, episodic use of dental services, socio-economic status and plaque trajectory), the prevalence ratio (PR) for having lost 1+ teeth by age 32 for the high-familial-risk group was 1.41 (95% confidence interval [CI] 1.05, 1.88) and the rate ratio for DMFS at age 32 was 1.41 (95% CI 1.24, 1.60). In the high-familial-risk group, the PR of following a high caries trajectory was 2.05 (95% CI 1.37, 3.06). Associations were strongest when information was available about both parents’ oral health. Nonetheless, when information was available for one parent only, associations were significant for some proband outcomes. Conclusions People with poor oral health tend to have parents with poor oral health. Family/parental history of oral health is a valid representation of the intricacies of the shared genetic and environmental factors that contribute to an individual’s oral health status. Associations were strongest when data from both parents can be obtained. PMID:22022823

Occlusal changes following posterior tooth loss in adults. Part 1: a study of clinical parameters associated with the extent and type of supraeruption in unopposed posterior teeth.

PubMed

Craddock, Helen L; Youngson, Callum C; Manogue, Michael; Blance, Andrew

2007-01-01

One of the barriers to restoring an edentulous space may be the supraeruption of an unopposed tooth to occupy some or all of the space needed for prosthetic replacement. The aim of this study was to determine the extent and type of supraeruption associated with unopposed posterior teeth and to investigate the relationship between these and oral and patient factors. Diagnostic casts of 100 patients with an unopposed posterior tooth and of 100 control patients were scanned and analyzed to record the extent of supraeruption, together with other clinical parameters. The type of eruption present was defined for each subject as Periodontal Growth, Active Eruption, or Relative Wear. Generalized Linear Models were developed to examine associations between the extent and type of supraeruption and patient or dental factors. The extent of supraeruption for an individual was modeled to show association between the degree of supraeruption and clinical parameters. Three models were produced to show associations between each type of supraeruption and clinical parameters. The mean supraeruption for subjects was 1.68 mm (SD 0.79, range 0 to 3.99 mm) and for controls, 0.24 mm (SD 0.39, range 0 to 1.46 mm). The extent of supraeruption was statistically greater in maxillary unopposed teeth than in mandibular unopposed teeth. Supraeruption was found in 92% of subjects' unopposed teeth. A Generalized Linear Model could be produced to demonstrate that the clinical parameters associated with supraeruption are periodontal growth, attachment loss, and the lingual movement of the tooth distal to the extraction site. Three types of supraeruption, which may be present singly, or in combination, can be identified. Active eruption has an association with attachment loss. Periodontal growth has an inverse association with attachment loss, is more prevalent in younger patients, in the maxilla, in premolars, and in females. Relative wear has an association with increasing age and is more prevalent in unopposed mandibular teeth.

Complications and survival rates of teeth after dental trauma over a 5-year period.

PubMed

Bücher, Katharina; Neumann, Claudia; Thiering, Elisabeth; Hickel, Reinhard; Kühnisch, Jan

2013-06-01

The purpose of this study was to evaluate whether the current guidelines of the International Association of Dental Traumatology (IADT) for emergency care of traumatised teeth result in lower complication rates. Therapeutic strategies of 361 dental injuries in 291 patients treated at a university dental hospital over a 5-year period were investigated by evaluating the patients' records. Adherence to the guidelines of the IADT (Flores et al. Dent Traumatol 17:1-4, 2001; 49-52, 2001; 97-102, 2001; 145-148, 2001; and 193-196, 2001; Flores et al. Dent Traumatol 23:66-71, 2007; 130-136, 2007; and 196-202, 2007) was evaluated. Complications were also recorded according to the patients' records and analysed relative to the treatment and injury pattern. During follow-up visits, the teeth were inspected regarding pulp vitality and overall function of the injured tooth. The Kaplan-Meier survival analysis of pulps and teeth was performed for different injury categories. The majority of injuries (322/361; 89.2 %) were treated according to the guidelines. When IADT guidelines were followed, complication rates were significantly lower than for cases treated without adherence to the guidelines. The most frequent complication was the loss of restoration, followed by pulp necrosis, abnormal mobility, and tooth loss. The overall survival analysis showed that in the permanent dentition, the loss of pulp vitality and tooth occurs within the first 6 months but may also occur later. The results of this study indicate that traumatised teeth that were treated according to the recommendations had a lower complication rate. In addition, the majority of pulp necrosis and tooth losses in the permanent dentition occurred within the first 6 months after trauma. These results indicate that early follow-up visits are essential to promptly treat complications. Adherence to the IADT guidelines for treatment of dental trauma may lead to more favourable outcomes when compared to cases treated without compliance to the guidelines.

High Speed Gear Sized and Configured to Reduce Windage Loss

NASA Technical Reports Server (NTRS)

Kunz, Robert F. (Inventor); Medvitz, Richard B. (Inventor); Hill, Matthew John (Inventor)

2013-01-01

A gear and drive system utilizing the gear include teeth. Each of the teeth has a first side and a second side opposite the first side that extends from a body of the gear. For each tooth of the gear, a first extended portion is attached to the first side of the tooth to divert flow of fluid adjacent to the body of the gear to reduce windage losses that occur when the gear rotates. The gear may be utilized in drive systems that may have high rotational speeds, such as speeds where the tip velocities are greater than or equal to about 68 m/s. Some embodiments of the gear may also utilize teeth that also have second extended portions attached to the second sides of the teeth to divert flow of fluid adjacent to the body of the gear to reduce windage losses that occur when the gear rotates.

Periodontal aspects of the juvenile form of paracoccidioidomycosis.

PubMed

Migliari, D A; Sugaya, N N; Mimura, M A; Cucé, L C

1998-01-01

Three cases of the juvenile form of paracoccidioidomycosis are reported. Emphasis has been given to the oral manifestations, particularly the periodontal involvement. The main periodontal findings were: generalized and progressive alveolar bone destruction leading to gingival recession with exposure of the tooth roots, and spontaneous tooth losses. The gingival mucosa was predominantly smooth, erythematous and slightly swollen. These aspects, although rare, may be the earliest signs of the disease and sometimes its only manifestations.

Oral health of the Paleoamericans of Lagoa Santa, Central Brazil.

PubMed

Da-Gloria, Pedro; Larsen, Clark Spencer

2014-05-01

The peopling, origins, and early prehistory of the Americas are topics of intense debate. However, few studies have used human remains to document and interpret patterns of health and lifestyle of Paleoamericans. This study provides the first investigation to characterize oral health in a series of early Holocene skeletal remains from Lagoa Santa, Brazil, a locality containing the remains of some of the earliest inhabitants of South America (10,000-7,000 BP). The sample is composed of 949 teeth and 1925 alveoli from an estimated 113 individuals excavated from 17 archaeological sites located in the State of Minas Gerais. We compare dental caries and abscess prevalence at Lagoa Santa to a large sample of human skeletons from the Western Hemisphere Project (WHP) database using both individual and tooth/alveolus count methods. In addition, antemortem tooth loss and tooth wear were analyzed in Lagoa Santa by sex and age. The results show that Lagoa Santa dental caries and abscess prevalence are significantly higher than observed among other hunter-gatherers included in the WHP database, except when abscess prevalence is considered by individual count. Adult females have less tooth wear coupled with higher prevalence of dental caries and antemortem tooth loss than adult males. These results point to an unexpected record of poor oral health at Lagoa Santa, especially among females. A diet based on a highly cariogenic combination of wild tubers and fruits is suggested as an explanation for the elevated rate, characterizing an early adaptation to a tropical environment in South America. Copyright © 2014 Wiley Periodicals, Inc.

Consensus Report of the European Federation of Conservative Dentistry: Erosive tooth wear – diagnosis and management.

PubMed

Carvalho, Thiago S; Colon, Pierre; Ganss, Carolina; Huysmans, Marie-Charlotte; Lussi, Adrian; Schlueter, Nadine; Schmalz, Gottfried; Shellis, Peter R; Björg Tveit, Anne; Wiegand, Annette

2016-01-01

Due to an increased focus on erosive tooth wear (ETW), the European Federation of Conservative Dentistry (EFCD) considered ETW as a relevant topic for generating this consensus report. This report is based on a compilation of the scientific literature, an expert conference, and the approval by the General Assembly of EFCD. ETW is a chemical-mechanical process resulting in a cumulative loss of hard dental tissue not caused by bacteria, and it is characterized by loss of the natural surface morphology and contour of the teeth. A suitable index for classification of ETW is the basic erosive wear examination (BEWE). Regarding the etiology, patient-related factors include the predisposition to erosion, reflux, vomiting, drinking and eating habits, as well as medications and dietary supplements. Nutritional factors relate to the composition of foods and beverages, e.g., with low pH and high buffer capacity (major risk factors), and calcium concentration (major protective factor). Occupational factors are exposition of workers to acidic liquids or vapors. Preventive management of ETWaims at reducing or stopping the progression of the lesions. Restorative management aims at reducing symptoms of pain and dentine hypersensitivity, or to restore esthetic and function, but it should only be used in conjunction with preventive strategies. Effective management of ETW includes screening for early signs of ETW and evaluating all etiological factors. ETW is a clinical condition, which calls for the increased attention of the dental community and is a challenge for the cooperation with other medical specialities.

How to determine spiral bevel gear tooth geometry for finite element analysis

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Litvin, Faydor L.

1991-01-01

An analytical method was developed to determine gear tooth surface coordinates of face milled spiral bevel gears. The method combines the basic gear design parameters with the kinematical aspects for spiral bevel gear manufacturing. A computer program was developed to calculate the surface coordinates. From this data a 3-D model for finite element analysis can be determined. Development of the modeling method and an example case are presented.

Serial removal of caries lesions from tooth occlusal surfaces using near-IR image-guided IR laser ablation

NASA Astrophysics Data System (ADS)

Chan, Kenneth H.; Tom, Henry; Darling, Cynthia L.; Fried, Daniel

2015-02-01

Previous studies have established that caries lesions can be imaged with high contrast without the interference of stains at near-IR wavelengths greater than 1300-nm. It has been demonstrated that computer controlled laser scanning systems utilizing IR lasers operating at high pulse repetition rates can be used for serial imaging and selective removal of caries lesions. In this study, we report our progress towards the development of algorithms for generating rasterized ablation maps from near-IR reflectance images for the removal of natural lesions from tooth occlusal surfaces. An InGaAs camera and a filtered tungsten-halogen lamp producing near-IR light in the range of 1500-1700-nm were used to collect crosspolarization reflectance images of tooth occlusal surfaces. A CO2 laser operating at a wavelength of 9.3- μm with a pulse duration of 10-15-μs was used for image-guided ablation.

Abfraction, abrasion, biocorrosion, and the enigma of noncarious cervical lesions: a 20-year perspective.

PubMed

Grippo, John O; Simring, Marvin; Coleman, Thomas A

2012-02-01

Hitherto, noncarious cervical lesions (NCCLs) of teeth have been generally ascribed to either toothbrush-dentifrice abrasion or acid "erosion." The last two decades have provided a plethora of new studies concerning such lesions. The most significant studies are reviewed and integrated into a practical approach to the understanding and designation of these lesions. A paradigm shift is suggested regarding use of the term "biocorrosion" to supplant "erosion" as it continues to be misused in the United States and many other countries of the world. Biocorrosion embraces the chemical, biochemical, and electrochemical degradation of tooth substance caused by endogenous and exogenous acids, proteolytic agents, as well as the piezoelectric effects only on dentin. Abfraction, representing the microstructural loss of tooth substance in areas of stress concentration, should not be used to designate all NCCLs because these lesions are commonly multifactorial in origin. Appropriate designation of a particular NCCL depends upon the interplay of the specific combination of three major mechanisms: stress, friction, and biocorrosion, unique to that individual case. Modifying factors, such as saliva, tongue action, and tooth form, composition, microstructure, mobility, and positional prominence are elucidated. By performing a comprehensive medical and dental history, using precise terms and concepts, and utilizing the Revised Schema of Pathodynamic Mechanisms, the dentist may successfully identify and treat the etiology of root surface lesions. Preventive measures may be instituted if the causative factors are detected and their modifying factors are considered. © 2011 Wiley Periodicals, Inc.

Alveoli, teeth, and tooth loss: Understanding the homology of internal mandibular structures in mysticete cetaceans

PubMed Central

Pyenson, Nicholas D.; Uhen, Mark D.; Marshall, Christopher D.

2017-01-01

The evolution of filter feeding in baleen whales (Mysticeti) facilitated a wide range of ecological diversity and extreme gigantism. The innovation of filter feeding evolved in a shift from a mineralized upper and lower dentition in stem mysticetes to keratinous baleen plates that hang only from the roof of the mouth in extant species, which are all edentulous as adults. While all extant mysticetes are born with a mandible lacking a specialized feeding structure (i.e., baleen), the bony surface retains small foramina with elongated sulci that often merge together in what has been termed the alveolar gutter. Because mysticete embryos develop tooth buds that resorb in utero, these foramina have been interpreted as homologous to tooth alveoli in other mammals. Here, we test this homology by creating 3D models of the internal mandibular morphology from terrestrial artiodactyls and fossil and extant cetaceans, including stem cetaceans, odontocetes and mysticetes. We demonstrate that dorsal foramina on the mandible communicate with the mandibular canal via smaller canals, which we explain within the context of known mechanical models of bone resorption. We suggest that these dorsal foramina represent distinct branches of the inferior alveolar nerve (or artery), rather than alveoli homologous with those of other mammals. As a functional explanation, we propose that these branches provide sensation to the dorsal margin of the mandible to facilitate placement and occlusion of the baleen plates during filer feeding. PMID:28542468

Cutting blade dentitions in squaliform sharks form by modification of inherited alternate tooth ordering patterns

PubMed Central

Smith, Moya Meredith

2016-01-01

The squaliform sharks represent one of the most speciose shark clades. Many adult squaliforms have blade-like teeth, either on both jaws or restricted to the lower jaw, forming a continuous, serrated blade along the jaw margin. These teeth are replaced as a single unit and successor teeth lack the alternate arrangement present in other elasmobranchs. Micro-CT scans of embryos of squaliforms and a related outgroup (Pristiophoridae) revealed that the squaliform dentition pattern represents a highly modified version of tooth replacement seen in other clades. Teeth of Squalus embryos are arranged in an alternate pattern, with successive tooth rows containing additional teeth added proximally. Asynchronous timing of tooth production along the jaw and tooth loss prior to birth cause teeth to align in oblique sets containing teeth from subsequent rows; these become parallel to the jaw margin during ontogeny, so that adult Squalus has functional tooth rows comprising obliquely stacked teeth of consecutive developmental rows. In more strongly heterodont squaliforms, initial embryonic lower teeth develop into the oblique functional sets seen in adult Squalus, with no requirement to form, and subsequently lose, teeth arranged in an initial alternate pattern. PMID:28018617

Bone marrow-derived stromal cells are more beneficial cell sources for tooth regeneration compared with adipose-derived stromal cells.

PubMed

Ye, Lanfeng; Chen, Lin; Feng, Fan; Cui, Junhui; Li, Kaide; Li, Zhiyong; Liu, Lei

2015-10-01

Tooth loss is presently a global epidemic and tooth regeneration is thought to be a feasible and ideal treatment approach. Choice of cell source is a primary concern in tooth regeneration. In this study, the odontogenic differentiation potential of two non-dental-derived stem cells, adipose-derived stromal cells (ADSCs) and bone marrow-derived stromal cells (BMSCs), were evaluated both in vitro and in vivo. ADSCs and BMSCs were induced in vitro in the presence of tooth germ cell-conditioned medium (TGC-CM) prior to implantation into the omentum majus of rats, in combination with inactivated dentin matrix (IDM). Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the mRNA expression levels of odontogenic-related genes. Immunofluorescence and immunohistochemical assays were used to detect the protein levels of odontogenic-specific genes, such as DSP and DMP-1 both in vitro and in vivo. The results suggest that both ADSCs and BMSCs have odontogenic differentiation potential. However, the odontogenic potential of BMSCs was greater compared with ADSCs, showing that BMSCs are a more appropriate cell source for tooth regeneration. © 2015 International Federation for Cell Biology.

Cutting blade dentitions in squaliform sharks form by modification of inherited alternate tooth ordering patterns

NASA Astrophysics Data System (ADS)

Underwood, Charlie; Johanson, Zerina; Smith, Moya Meredith

2016-11-01

The squaliform sharks represent one of the most speciose shark clades. Many adult squaliforms have blade-like teeth, either on both jaws or restricted to the lower jaw, forming a continuous, serrated blade along the jaw margin. These teeth are replaced as a single unit and successor teeth lack the alternate arrangement present in other elasmobranchs. Micro-CT scans of embryos of squaliforms and a related outgroup (Pristiophoridae) revealed that the squaliform dentition pattern represents a highly modified version of tooth replacement seen in other clades. Teeth of Squalus embryos are arranged in an alternate pattern, with successive tooth rows containing additional teeth added proximally. Asynchronous timing of tooth production along the jaw and tooth loss prior to birth cause teeth to align in oblique sets containing teeth from subsequent rows; these become parallel to the jaw margin during ontogeny, so that adult Squalus has functional tooth rows comprising obliquely stacked teeth of consecutive developmental rows. In more strongly heterodont squaliforms, initial embryonic lower teeth develop into the oblique functional sets seen in adult Squalus, with no requirement to form, and subsequently lose, teeth arranged in an initial alternate pattern.

Auditory function in children with Charcot-Marie-Tooth disease.

PubMed

Rance, Gary; Ryan, Monique M; Bayliss, Kristen; Gill, Kathryn; O'Sullivan, Caitlin; Whitechurch, Marny

2012-05-01

The peripheral manifestations of the inherited neuropathies are increasingly well characterized, but their effects upon cranial nerve function are not well understood. Hearing loss is recognized in a minority of children with this condition, but has not previously been systemically studied. A clear understanding of the prevalence and degree of auditory difficulties in this population is important as hearing impairment can impact upon speech/language development, social interaction ability and educational progress. The aim of this study was to investigate auditory pathway function, speech perception ability and everyday listening and communication in a group of school-aged children with inherited neuropathies. Twenty-six children with Charcot-Marie-Tooth disease confirmed by genetic testing and physical examination participated. Eighteen had demyelinating neuropathies (Charcot-Marie-Tooth type 1) and eight had the axonal form (Charcot-Marie-Tooth type 2). While each subject had normal or near-normal sound detection, individuals in both disease groups showed electrophysiological evidence of auditory neuropathy with delayed or low amplitude auditory brainstem responses. Auditory perception was also affected, with >60% of subjects with Charcot-Marie-Tooth type 1 and >85% of Charcot-Marie-Tooth type 2 suffering impaired processing of auditory temporal (timing) cues and/or abnormal speech understanding in everyday listening conditions.

Influence of the shape of the layers in photo-cured dental restorations on the shrinkage stress peaks-FEM study.

PubMed

Kowalczyk, Piotr

2009-12-01

The aim of the paper is to analyse an influence of the shape of the layers in photo-cured dental restorations of Class I on distribution of shrinkage stresses along the tooth-restoration interface. The study is a continuation of the previous considerations (Kowalczyk and Gambin (2008) [1]), where techniques, which reduce stress concentration at the top of the tooth-restoration interface, were considered. The analysis leads to proposition of new layer forming techniques, which diminish the stress peaks at the interface and prevent the crack propagation process. To find the stress distributions in the dental restoration layers and the tooth tissues the finite element method implemented in the ABAQUS (Simulia, Providence, USA) software is used. For Class I restoration of the premolar tooth, the axisymmetrical model is assumed. The restoration is made of four layers of a photo-cured composite. Between the tooth tissues and the restoration, a layer of bonding agent 0.01mm thick is placed and modeled by FEM with help of the cohesive elements. The assumed model takes into account an influence of changes of elastic properties and viscous effects. For each case of the restoration layers system, the Huber-Mises stresses are analysed. The investigations show that the stresses near the restoration-tooth tissue interface are reduced due to viscous flow of the cured material and due to existence of a thin layer of the bonding agent. However, the stress distribution both, in the restoration and in the tooth tissues, is strongly dependent on a shape of the filling layers. Numerical simulations disclose that stress peaks are located at the top corners of each layer. The top corners of the last layer are the places where microleakage may occur. Stress concentrations at the corners of the preceding layers may lead to a growth of uprising crack. It will be shown that the flat layers in the restoration create relatively high values of the stress peaks. The rounded layers, with shapes close to those used in dental practice, reduce maximal stresses about 40%. According to a common opinion of dentists, the wedge-shaped layers give the best result. In the present paper, another way of the shrinkage stress reduction is proposed. Before the layering, one can cover the surface of the tooth cavity with a thin "pre-layer". Next, the remainder cavity may be filled with flat, rounded or wedged layers. It will be shown, that in the fillings with the pre-layers, stress peaks are reduced up to 75%, with respect to the fillings composed of the rounded layers only. The proposed method considerably reduces the shrinkage stress, both in the tooth restoration, as well as, in the tooth tissues. The fillings with the pre-layer are easy in application and its analysis gives promising results. The pre-layer may be applied with other layers of different shapes, and its thickness may vary. The method is recommended for cavities with a great loss of the tooth tissue.

Developmental Disturbances of a Maxillary Central Incisor due to Trauma to Its Predecessor: A Case Report

PubMed Central

Karataş, Merve Safa; Sönmez, Işıl Şaroğlu

2013-01-01

Objective To report the effects of a primary tooth trauma on the underlying permanent tooth germ. Clinical Presentation and Intervention A 12-year-old girl was referred to our clinic with a complaint of poor aesthetic appearance. The crown of the permanent maxillary left central tooth exhibited an increased clinical crown height with an ‘enamel hyperplasia’ in the cervical third and had hypoplastic enamel with yellowish-brown discoloration extending from the middle third to the incisal edge. Radiographic examination revealed that the permanent maxillary left central tooth had abnormal root morphology with root dilaceration. The patient revealed a history of trauma at the age of 4 years. An aesthetic restoration with light-curing resin composite was performed on the vestibular surface of the maxillary left permanent central tooth. Conclusion Sequelae of a primary tooth trauma on the permanent tooth were restored. We recommend that parents should be aware of the consequences of untreated trauma to a primary tooth. Educational and preventive programmes on dental trauma are required to educate parents about emergency knowledge and sequelae of dental trauma. PMID:23689528

Comparative evaluation of two different remineralizing agents on the microhardness of bleached enamel surface: Results of an in vitro study.

PubMed

Kaur, Gunpriya; Sanap, Anita U; Aggarwal, Shalini D; Kumar, Tanaya

2015-01-01

Various agents are studied for their remineralization potential. To evaluate the effect of GC Tooth Mousse and Toothmin Tooth Cream on microhardness of bleached enamel. In vitro- study. Twenty freshly extracted anterior teeth were cut sagittally and impregnated in cold cure acrylic resin. Specimens were kept in artificial saliva to prevent from dehydration. After measuring baseline hardness, teeth were randomly divided into two groups. Everbrite In - Office Tooth whitening kit (Dentamerica) was used to demineralize the teeth following which hardness was measured again. Teeth in group one (n=10) and group two (n=10) were treated with GC tooth mousse (Recaldent) and Toothmin tooth cream (Abbott Healthcare Pvt.Ltd) daily for seven days and microhardness of enamel surface was measured. Mean, SD, and percentage change in the microhardness were calculated. Student's paired t-test was used to evaluate the signifi cance of change from initial, after bleaching for 5 min and after 1-week remineralization Unpaired't' test was used to compare difference between groups. Microhardness significantly decreased in both groups after bleaching (% change group one: 3.24% group two: 3.26% in group; P<0.01 in both groups). Both products significantly increased mineralization after seven days of treatment (P<0.01). Remineralization was numerically better in Toothmin group (Abbott Healthcare Pvt.Ltd ) compared to GC Mousse(Recaldent) (% change 3.27% vs 6.34%). However, difference was not significant (P >0.05). Both GC Tooth Mousse (Recaldent) and Toothmin Tooth cream (Abbott Healthcare Pvt.Ltd) increase the microhardness of bleached enamel. Toothmin tooth cream is a better agent for increasing microhardness, although difference is not significant.

Procedure for Tooth Contact Analysis of a Face Gear Meshing With a Spur Gear Using Finite Element Analysis

NASA Technical Reports Server (NTRS)

Bibel, George; Lewicki, David G. (Technical Monitor)

2002-01-01

A procedure was developed to perform tooth contact analysis between a face gear meshing with a spur pinion using finite element analysis. The face gear surface points from a previous analysis were used to create a connected tooth solid model without gaps or overlaps. The face gear surface points were used to create a five tooth face gear Patran model (with rim) using Patran PCL commands. These commands were saved in a series of session files suitable for Patran input. A four tooth spur gear that meshes with the face gear was designed and constructed with Patran PCL commands. These commands were also saved in a session files suitable for Patran input. The orientation of the spur gear required for meshing with the face gear was determined. The required rotations and translations are described and built into the session file for the spur gear. The Abaqus commands for three-dimensional meshing were determined and verified for a simplified model containing one spur tooth and one face gear tooth. The boundary conditions, loads, and weak spring constraints were determined to make the simplified model work. The load steps and load increments to establish contact and obtain a realistic load was determined for the simplified two tooth model. Contact patterns give some insight into required mesh density. Building the two gears in two different local coordinate systems and rotating the local coordinate systems was verified as an easy way to roll the gearset through mesh. Due to limitation of swap space, disk space and time constraints of the summer period, the larger model was not completed.

Adhesion of Dental Materials to Tooth Structure

NASA Astrophysics Data System (ADS)

Mitra, Sumita B.

2000-03-01

The understanding and proper application of the principles of adhesion has brought forth a new paradigm in the realm of esthetic dentistry. Modern restorative tooth procedures can now conserve the remaining tooth-structure and also provide for the strengthening of the tooth. Adhesive restorative techniques call for the application and curing of the dental adhesive at the interface between the tooth tissue and the filling material. Hence the success of the restoration depends largely on the integrity of this interface. The mechanism of adhesion of the bonding materials to the dental hard tissue will be discussed in this paper. There are four main steps that occur during the application of the dental adhesive to the oral hard tissues: 1) The first step is the creation of a microstructure in the tooth enamel or dentin by means of an acidic material. This can be through the application of a separate etchant or can be accomplished in situ by the adhesive/primer. This agent has to be effective in removing or modifying the proteinaceous “smear” layer, which would otherwise act as a weak boundary layer on the surface to be bonded. 2) The primer/adhesive must then be able to wet and penetrate the microstructure created in the tooth. Since the surface energies of etched enamel and that of etched dentin are different finding one material to prime both types of dental tissues can be quite challenging. 3) The ionomer types of materials, particularly those that are carboxylate ion-containing, can chemically bond with the calcium ions of the hydroxyapatite mineral. 4) Polymerization in situ allows for micromechanical interlocking of the adhesive. The importance of having the right mechanical properties of the cured adhesive layer and its role in absorbing and dissipating stresses encountered by a restored tooth will also be discussed.

An advanced approach for computer modeling and prototyping of the human tooth.

PubMed

Chang, Kuang-Hua; Magdum, Sheetalkumar; Khera, Satish C; Goel, Vijay K

2003-05-01

This paper presents a systematic and practical method for constructing accurate computer and physical models that can be employed for the study of human tooth mechanics. The proposed method starts with a histological section preparation of a human tooth. Through tracing outlines of the tooth on the sections, discrete points are obtained and are employed to construct B-spline curves that represent the exterior contours and dentino-enamel junction (DEJ) of the tooth using a least square curve fitting technique. The surface skinning technique is then employed to quilt the B-spline curves to create a smooth boundary and DEJ of the tooth using B-spline surfaces. These surfaces are respectively imported into SolidWorks via its application protocol interface to create solid models. The solid models are then imported into Pro/MECHANICA Structure for finite element analysis (FEA). The major advantage of the proposed method is that it first generates smooth solid models, instead of finite element models in discretized form. As a result, a more advanced p-FEA can be employed for structural analysis, which usually provides superior results to traditional h-FEA. In addition, the solid model constructed is smooth and can be fabricated with various scales using the solid freeform fabrication technology. This method is especially useful in supporting bioengineering applications, where the shape of the object is usually complicated. A human maxillary second molar is presented to illustrate and demonstrate the proposed method. Note that both the solid and p-FEA models of the molar are presented. However, comparison between p- and h-FEA models is out of the scope of the paper.

Soft Drink, Software and Softening of Teeth – a Case Report of Tooth Wear in the Mixed Dentition Due to a Combination of Dental Erosion and Attrition

PubMed Central

Gambon, D. L; Brand, H. S; Nieuw Amerongen, A.V

2010-01-01

This case report describes a 9-year-old boy with severe tooth wear as a result of drinking a single glass of soft drink per day. This soft drink was consumed over a period of one to two hours, while he was gaming intensively on his computer. As a result, a deep bite, enamel cupping, sensitivity of primary teeth and loss of fillings occurred. Therefore, dentists should be aware that in patients who are gaming intensively, the erosive potential of soft drinks can be potentiated by mechanical forces leading to excessive tooth wear. PMID:21243073

Dental health state utility values associated with tooth loss in two contrasting cultures.

PubMed

Nassani, M Z; Locker, D; Elmesallati, A A; Devlin, H; Mohammadi, T M; Hajizamani, A; Kay, E J

2009-08-01

The study aimed to assess the value placed on oral health states by measuring the utility of mouths in which teeth had been lost and to explore variations in utility values within and between two contrasting cultures, UK and Iran. One hundred and fifty eight patients, 84 from UK and 74 from Iran, were recruited from clinics at University-based faculties of dentistry. All had experienced tooth loss and had restored or unrestored dental spaces. They were presented with 19 different scenarios of mouths with missing teeth. Fourteen involved the loss of one tooth and five involved shortened dental arches (SDAs) with varying numbers of missing posterior teeth. Each written description was accompanied by a verbal explanation and digital pictures of mouth models. Participants were asked to indicate on a standardized Visual Analogue Scale how they would value the health of their mouth if they had lost the tooth/teeth described and the resulting space was left unrestored. With a utility value of 0.0 representing the worst possible health state for a mouth and 1.0 representing the best, the mouth with the upper central incisor missing attracted the lowest utility value in both samples (UK = 0.16; Iran = 0.06), while the one with a missing upper second molar the highest utility values (0.42, 0.39 respectively). In both countries the utility value increased as the tooth in the scenario moved from the anterior towards the posterior aspect of the mouth. There were significant differences in utility values between UK and Iranian samples for four scenarios all involving the loss of anterior teeth. These differences remained after controlling for gender, age and the state of the dentition. With respect to the SDA scenarios, a mouth with a SDA with only the second molar teeth missing in all quadrants attracted the highest utility values, while a mouth with an extreme SDA with both missing molar and premolar teeth in all quadrants attracted the lowest utility values. The study provided further evidence of the validity of the scaling approach to utility measurement in mouths with missing teeth. Some cross-cultural variations in values were observed but these should be viewed with due caution because the magnitude of the differences was small.

Effects of amorphous calcium phosphate stabilized by casein phosphopeptides on enamel de- and remineralization in primary teeth: an in vitro study.

PubMed

Bar-Hillel, Rita; Feuerstein, Osnat; Tickotsky, Nili; Shapira, Joseph; Moskovitz, Moti

2012-01-01

Amorphous calcium phosphate, stabilized by casein phosphopeptides, has been found to enhance remineralization of subsurface lesions in permanent teeth. The purpose of the present in vitro study was to evaluate the potential of GC Tooth Mousse to enhance remineralization of initial demineralized enamel sites in primary teeth. Forty-four demineralization sites were created in 22 extracted primary teeth. Samples were randomly assigned to 6 treatment groups (GC Tooth Mousse covering, GC Tooth Mousse covering and demineralization, and control groups). The mineral content of each sample was evaluated using energy dispersive X-ray analysis, performed from the enamel surface of each lesion inwards. The results were analyzed using analysis of variance, with a significance level P<.05. Samples treated with GC Tooth Mousse demonstrated an increase in the calcium-phosphate ratio by approximately 2% near the surface, a minimal increase of 1% at a depth over 60 μm, and no change at a depth from 40 to 60 μm, with no statistically significant differences (P>.05). This study demonstrates a minimal increase in the subsurface calcium-phosphate ratio following GC Tooth Mousse treatment, especially in demineralized enamel tissue.

Modelling of micromachining of human tooth enamel by erbium laser radiation

NASA Astrophysics Data System (ADS)

Belikov, A. V.; Skrypnik, A. V.; Shatilova, K. V.

2014-08-01

We consider a 3D cellular model of human tooth enamel and a photomechanical cellular model of enamel ablation by erbium laser radiation, taking into account the structural peculiarities of enamel, energy distribution in the laser beam cross section and attenuation of laser energy in biological tissue. The surface area of the texture in enamel is calculated after its micromachining by erbium laser radiation. The influence of the surface area on the bond strength of enamel with dental filling materials is discussed. A good correlation between the computer simulation of the total work of adhesion and experimentally measured bond strength between the dental filling material and the tooth enamel after its micromachining by means of YAG : Er laser radiation is attained.

Estimation of background radiation doses for the Peninsular Malaysia's population by ESR dosimetry of tooth enamel.

PubMed

Rodzi, Mohd; Zhumadilov, Kassym; Ohtaki, Megu; Ivannikov, Alexander; Bhattacharjee, Deborshi; Fukumura, Akifumi; Hoshi, Masaharu

2011-08-01

Background radiation dose is used in dosimetry for estimating occupational doses of radiation workers or determining radiation dose of an individual following accidental exposure. In the present study, the absorbed dose and the background radiation level are determined using the electron spin resonance (ESR) method on tooth samples. The effect of using different tooth surfaces and teeth exposed with single medical X-rays on the absorbed dose are also evaluated. A total of 48 molars of position 6-8 were collected from 13 district hospitals in Peninsular Malaysia. Thirty-six teeth had not been exposed to any excessive radiation, and 12 teeth had been directly exposed to a single X-ray dose during medical treatment prior to extraction. There was no significant effect of tooth surfaces and exposure with single X-rays on the measured absorbed dose of an individual. The mean measured absorbed dose of the population is 34 ± 6.2 mGy, with an average tooth enamel age of 39 years. From the slope of a regression line, the estimated annual background dose for Peninsular Malaysia is 0.6 ± 0.3 mGy y(-1). This value is slightly lower than the yearly background dose for Malaysia, and the radiation background dose is established by ESR tooth measurements on samples from India and Russia.

Accelerated tooth movement with piezocision and its periodontal-transversal effects in patients with Class II malocclusion.

PubMed

Aksakalli, Sertac; Calik, Berra; Kara, Burcak; Ezirganli, Seref

2016-01-01

To compare the extent of canine distalization and the transversal changes, postdistalization gingival indices, and mobility scores between patients who were undergoing orthodontic treatment involving upper premolar extraction with (experimental group) or without piezocision. Twenty maxillary canines of 10 patients were evaluated with split mouth design. Pre- and postdistalization dental casts were prepared and scanned with an orthodontic scanner to compare the extent of distalization and transversal changes between the two groups. The pre- and postdistalization gingival indices and mobility scores were also calculated. Three-dimensional analysis of the models revealed significant differences in tooth movement (lesser anchorage loss and greater canine distalization) between the experimental and control groups. Furthermore, the distalization time was shortened in the experimental group. There were no differences in the transversal changes, pre- and postdistalization gingival indices, or mobility scores between groups. Piezocision-assisted distalization accelerates tooth movement, decreases the anchorage loss for posterior teeth, and does not induce any maxillary transversal change. Moreover, piezocision does not have any adverse effects on periodontal health.

Hunter-Schreger Band patterns in human tooth enamel

PubMed Central

Lynch, Christopher D; O’Sullivan, Victor R; Dockery, Peter; McGillycuddy, Catherine T; Sloan, Alastair J

2010-01-01

Using light microscopy, we examined Hunter-Schreger Band (HSB) patterns on the axial and occlusal/incisal surfaces of 160 human teeth, sectioned in both the buccolingual and mesiodistal planes. We found regional variations in HSB packing densities (number of HSBs per mm of amelodentinal junction length) and patterns throughout the crown of each class of tooth (maxillary and mandibular: incisor, canine, premolar, and molar) examined. HSB packing densities were greatest in areas where functional and occlusal loads are greatest, such as the occlusal surfaces of posterior teeth and the incisal regions of incisors and canines. From this it is possible to infer that the behaviour of ameloblasts forming enamel prisms during amelogenesis is guided by genetic/evolutionary controls that act to increase the fracture and wear resistance of human tooth enamel. It is suggested that HSB packing densities and patterns are important in modern clinical dental treatments, such as the bonding of adhesive restorations to enamel, and in the development of conditions, such as abfraction and cracked tooth syndrome. PMID:20579171

Effect of Er,Cr:YSGG laser irradiation on bovine enamel surface during in-office tooth bleaching ex vivo.

PubMed

Dionysopoulos, Dimitrios; Strakas, Dimitrios; Koliniotou-Koumpia, Eugenia; Koumpia, Effimia

2017-07-01

The aim of this in vitro study was to evaluate the effect of using Er,Cr:YSGG laser during in-office tooth bleaching on bovine enamel surface to evaluate the safety of this therapy on tooth tissues. Thirty-six enamel specimens were prepared from bovine incisors and divided into three groups: Group 1 specimens (control) received no bleaching treatment; Group 2 received a conventional in-office bleaching treatment (40 % H 2 O 2 ); Group 3 received laser-assisted bleaching procedure (40 % H 2 O 2 ) utilizing an Er,Cr:YSGG laser. The specimens were stored for 10 days after the bleaching treatment in artificial saliva. Vickers hardness was determined using a microhardness tester, and measurements for surface roughness were done using a VSI microscope. Three specimens for each experimental group were examined under SEM and mineral composition of the specimens was evaluated using EDS. Data were statistically analyzed using one-way ANOVA, Tukey's post hoc, Wilcoxon signed rank and Kruskal-Wallis tests (a = 0.05). The Vickers hardness of the enamel was reduced after in-office bleaching procedures (p < 0.05), and changes in surface morphology of the enamel were observed. However, the surface roughness of the enamel was not influenced (p > 0.05), and no changes in mineral composition of the enamel were detected after in-office bleaching procedures (p > 0.05). The laser-assisted bleaching treatment with Er,Cr:YSGG laser did not influence the enamel surface compared to the conventional bleaching technique. The safety of the use of Er,Cr:YSGG laser during in-office tooth bleaching regarding the surface properties of the enamel was confirmed under in vitro conditions.

Evaluation of Surface Fatigue Strength Based on Surface Temperature

NASA Astrophysics Data System (ADS)

Deng, Gang; Nakanishi, Tsutomu

Surface temperature is considered to be an integrated index that is dependent on not only the load and the dimensions at the contact point but also the sliding velocity, rolling velocity, surface roughness, and lubrication conditions. Therefore, the surface durability of rollers and gears can be evaluated more exactly and simply by the use of surface temperature rather than Hertzian stress. In this research, surface temperatures of rollers under different rolling and sliding conditions are measured using a thermocouple. The effects of load P, mean velocity Vm and sliding velocity Vs on surface temperature are clarified. An experimental formula, which expresses the linear relationship between surface temperature and the P0.86Vs1.31Vm-0.83 value, is used to determine surface temperature. By comparing calculated and measured temperature on the tooth surface of a gear, this formula is confirmed to be applicable for gear tooth surface temperature calculation.

Massive losses of taste receptor genes in toothed and baleen whales.

PubMed

Feng, Ping; Zheng, Jinsong; Rossiter, Stephen J; Wang, Ding; Zhao, Huabin

2014-05-06

Taste receptor genes are functionally important in animals, with a surprising exception in the bottlenose dolphin, which shows extensive losses of sweet, umami, and bitter taste receptor genes. To examine the generality of taste gene loss, we examined seven toothed whales and five baleen whales and sequenced the complete repertoire of three sweet/umami (T1Rs) and ten bitter (T2Rs) taste receptor genes. We found all amplified T1Rs and T2Rs to be pseudogenes in all 12 whales, with a shared premature stop codon in 10 of the 13 genes, which demonstrated massive losses of taste receptor genes in the common ancestor of whales. Furthermore, we analyzed three genome sequences from two toothed whales and one baleen whale and found that the sour taste marker gene Pkd2l1 is a pseudogene, whereas the candidate salty taste receptor genes are intact and putatively functional. Additionally, we examined three genes that are responsible for taste signal transduction and found the relaxation of functional constraints on taste signaling pathways along the ancestral branch leading to whales. Together, our results strongly suggest extensive losses of sweet, umami, bitter, and sour tastes in whales, and the relaxation of taste function most likely arose in the common ancestor of whales between 36 and 53 Ma. Therefore, whales represent the first animal group to lack four of five primary tastes, probably driven by the marine environment with high concentration of sodium, the feeding behavior of swallowing prey whole, and the dietary switch from plants to meat in the whale ancestor. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Epidemiological studies of tooth wear and dental erosion in 14-year old children in North West England. Part 2: The association of diet and habits.

PubMed

Milosevic, A; Bardsley, P F; Taylor, S

2004-10-23

To determine the strength of association (expressed as Odds Ratios) of potential risk factors with erosion and tooth wear in 14-year-old schoolchildren. A random sample of 2,385 children were selected by a stratified two-stage technique based on schools and children. Schools in NW England. Tooth wear was assessed by one examiner on three surfaces of all 12 anterior teeth (labial, incisal and palatal) and the occlusal surface of all four first molars using a four-point scale. Enamel wear was scored 0, dentine exposure <1/3 scored 1, >1/3 scored 2 and secondary dentine or pulpal exposure, scored 3. A questionnaire enquired about general health, dental health, habits and the frequency of intake of a wide range of foods and drinks. The Odds Ratios for tooth wear on any surface for habits, reflux and certain foods were: bruxism, 1.10; stomach upset, 1.45; pickles 1.86; vinegar 1.36; salt and vinegar crisps 1.33; brown/other sauces 1.57. Similarly, the odds ratios for potentially erosive drinks were: fizzy drinks 1.32; sport drinks 1.58; herbal/lemon tea 3.97. The frequency of intake was bi-modal with 397 children drinking a can per day and 207 drinking two cans per day. A significant number drank acidic beverages at bedtime but this was not associated with dental erosion. Although odds ratios greater than unity indicate an association, this was not high for carbonated beverages and many other acidic foods or drinks. Examining at fourteen years may not be ideal, as the determinants of erosion/tooth wear have not acted for long, the indices do not discriminate sufficiently and proportionately few subjects have dentine exposed on smooth surfaces.

Properties of tooth enamel in great apes.

PubMed

Lee, James J-W; Morris, Dylan; Constantino, Paul J; Lucas, Peter W; Smith, Tanya M; Lawn, Brian R

2010-12-01

A comparative study has been made of human and great ape molar tooth enamel. Nanoindentation techniques are used to map profiles of elastic modulus and hardness across sections from the enamel-dentin junction to the outer tooth surface. The measured data profiles overlap between species, suggesting a degree of commonality in material properties. Using established deformation and fracture relations, critical loads to produce function-threatening damage in the enamel of each species are calculated for characteristic tooth sizes and enamel thicknesses. The results suggest that differences in load-bearing capacity of molar teeth in primates are less a function of underlying material properties than of morphology. Published by Elsevier Ltd.

Tooth wear and dentoalveolar remodeling are key factors of morphological variation in the Dmanisi mandibles

PubMed Central

Margvelashvili, Ann; Zollikofer, Christoph P. E.; Lordkipanidze, David; Peltomäki, Timo; Ponce de León, Marcia S.

2013-01-01

The Plio-Pleistocene hominin sample from Dmanisi (Georgia), dated to 1.77 million years ago, is unique in offering detailed insights into patterns of morphological variation within a paleodeme of early Homo. Cranial and dentoalveolar morphologies exhibit a high degree of diversity, but the causes of variation are still relatively unexplored. Here we show that wear-related dentoalveolar remodeling is one of the principal mechanisms causing mandibular shape variation in fossil Homo and in modern human hunter–gatherer populations. We identify a consistent pattern of mandibular morphological alteration, suggesting that dental wear and compensatory remodeling mechanisms remained fairly constant throughout the evolution of the genus Homo. With increasing occlusal and interproximal tooth wear, the teeth continue to erupt, the posterior dentition tends to drift in a mesial direction, and the front teeth become more upright. The resulting changes in dentognathic size and shape are substantial and need to be taken into account in comparative taxonomic analyses of isolated hominin mandibles. Our data further show that excessive tooth wear eventually leads to a breakdown of the normal remodeling mechanisms, resulting in dentognathic pathologies, tooth loss, and loss of masticatory function. Complete breakdown of dentognathic homeostasis, however, is unlikely to have limited the life span of early Homo because this effect was likely mediated by the preparation of soft foods. PMID:24101504

A systematic review of the clinical performance of tooth-retained and implant-retained double crown prostheses with a follow-up of ≥ 3 years.

PubMed

Verma, Rohini; Joda, Tim; Brägger, Urs; Wittneben, Julia-Gabriela

2013-01-01

The objective of this review was to systematically screen the literature for data related to the survival and complication rates observed with dental or implant double crown abutments and removable prostheses under functional loading for at least 3 years. A systematic review of the dental literature from January 1966 to December 2009 was performed in electronic databases (PubMed and Embase) as well as by an extensive hand search to investigate the clinical outcomes of double crown reconstructions. From the total of 2412 titles retrieved from the search, 65 were selected for full-text review. Subsequently, 17 papers were included for data extraction. An estimation of the cumulative survival and complication rates was not feasible due to the lack of detailed information. Tooth survival rates for telescopic abutment teeth ranged from 82.5% to 96.5% after an observation period of 3.4 to 6 years, and for tooth-supported double crown retained dentures from 66.7% to 98.6% after an observation period of 6 to 10 years. The survival rates of implants were between 97.9% and 100% and for telescopic-retained removable dental prostheses with two mandibular implants, 100% after 3.0 and 10.4 years. The major biological complications affecting the tooth abutments were gingival inflammation, periodontal disease, and caries. The most frequent technical complications were loss of cementation and loss of facings. The main findings of this review are: (I) double crown tooth abutments and dentures demonstrated a wide range of survival rates. (II) Implant-supported mandibular overdentures demonstrated a favorable long-term prognosis. (III) A greater need for prosthetic maintenance is required for both tooth-supported and implant-supported reconstructions. (IV) Future areas of research would involve designing appropriate longitudinal studies for comparisons of survival and complication rates of different reconstruction designs. © 2012 by the American College of Prosthodontists.

Effect of Different Ceramic Crown Preparations on Tooth Structure Loss: An In Vitro Study

NASA Astrophysics Data System (ADS)

Ebrahimpour, Ashkan

Objective: To quantify and compare the amount of tooth-structure reduction following the full-coverage preparations for crown materials of porcelain-fused-to-metal, lithium disilicate glass-ceramic and yttria-stabilized tetragonal zirconia polycrystalline for three tooth morphologies. Methods: Groups of resin teeth of different morphologies were individually weighed to high precision, then prepared following the preparation guidelines. The teeth were re-weighed after preparation and the amount of structural reduction was calculated. Statistical analyses were performed to find out if there was a significant difference among the groups. Results: Amount of tooth reduction for zirconia crown preparations was the lowest and statistically different compared with the other two materials. No statistical significance was found between the amount of reduction for porcelain-fused-to-metal and lithium disilicate glass-ceramic crowns. Conclusion: Within the limitations of this study, more tooth structure can be saved when utilizing zirconia full-coverage restorations compared with lithium disilicate glass-ceramic and porcelain-fused-to-metal crowns in maxillary central incisors, first premolars and first molars.

Tooth fracture risk analysis based on a new finite element dental structure models using micro-CT data.

PubMed

Chen, G; Fan, W; Mishra, S; El-Atem, A; Schuetz, M A; Xiao, Y

2012-10-01

The finite element (FE) analysis is an effective method to study the strength and predict the fracture risk of endodontically-treated teeth. This paper presents a rapid method developed to generate a comprehensive tooth FE model using data retrieved from micro-computed tomography (μCT). With this method, the inhomogeneity of material properties of teeth was included into the model without dividing the tooth model into different regions. The material properties of the tooth were assumed to be related to the mineral density. The fracture risk at different tooth portions was assessed for root canal treatments. The micro-CT images of a tooth were processed by a Matlab software programme and the CT numbers were retrieved. The tooth contours were obtained with thresholding segmentation using Amira. The inner and outer surfaces of the tooth were imported into Solidworks and a three-dimensional (3D) tooth model was constructed. An assembly of the tooth model with the periodontal ligament (PDL) layer and surrounding bone was imported into ABAQUS. The material properties of the tooth were calculated from the retrieved CT numbers via ABAQUS user's subroutines. Three root canal geometries (original and two enlargements) were investigated. The proposed method in this study can generate detailed 3D finite element models of a tooth with different root canal enlargements and filling materials, and would be very useful for the assessment of the fracture risk at different tooth portions after root canal treatments. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

A method for determining spiral-bevel gear tooth geometry for finite element analysis

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Litvin, Faydor L.

1991-01-01

An analytical method was developed to determine gear tooth surface coordinates of face-milled spiral bevel gears. The method uses the basic gear design parameters in conjunction with the kinematical aspects of spiral bevel gear manufacturing machinery. A computer program, SURFACE, was developed. The computer program calculates the surface coordinates and outputs 3-D model data that can be used for finite element analysis. Development of the modeling method and an example case are presented. This analysis method could also find application for gear inspection and near-net-shape gear forging die design.

Monitoring tooth profile faults in epicyclic gearboxes using synchronously averaged motor currents: Mathematical modeling and experimental validation

NASA Astrophysics Data System (ADS)

Ottewill, J. R.; Ruszczyk, A.; Broda, D.

2017-02-01

Time-varying transmission paths and inaccessibility can increase the difficulty in both acquiring and processing vibration signals for the purpose of monitoring epicyclic gearboxes. Recent work has shown that the synchronous signal averaging approach may be applied to measured motor currents in order to diagnose tooth faults in parallel shaft gearboxes. In this paper we further develop the approach, so that it may also be applied to monitor tooth faults in epicyclic gearboxes. A low-degree-of-freedom model of an epicyclic gearbox which incorporates the possibility of simulating tooth faults, as well as any subsequent tooth contact loss due to these faults, is introduced. By combining this model with a simple space-phasor model of an induction motor it is possible to show that, in theory, tooth faults in epicyclic gearboxes may be identified from motor currents. Applying the synchronous averaging approach to experimentally recorded motor currents and angular displacements recorded from a shaft mounted encoder, validate this finding. Comparison between experiments and theory highlight the influence of operating conditions, backlash and shaft couplings on the transient response excited in the currents by the tooth fault. The results obtained suggest that the method may be a viable alternative or complement to more traditional methods for monitoring gearboxes. However, general observations also indicate that further investigations into the sensitivity and robustness of the method would be beneficial.

Erosion-protecting effect of oral-care products available on the Swiss market. A pilot study

PubMed

Wasser, Gregor; João-Souza, Samira H; Lussi, Adrian; Carvalho, Thiago S

2018-03-28

The present study sought to test oral-care products available on the Swiss market, such as toothpastes and gels, with respect to the protection of enamel against erosive tooth wear. A total of 56 enamel specimens were divided into 7 groups (n = 8): F-TP = Migros Budget Anti-Caries Toothpaste (Negative Control); F+Sn3500-TP = Elmex Erosion Protection Toothpaste (Positive Control); F-TP + F+Oligopep-Gel = Migros Budget Anti-Caries Toothpaste + Emofluor Protect Gel Professional; F+Sn3120-Gel = Emofluor Gel Intensive Care; F+Oligopep-TP = Candida Protect Professional Toothpaste; F+Sn1260-TP = Emoform-F Protect Toothpaste; and F+Sn3440-TP = Sensodyne Repair & Protect Toothpaste. The specimens were incubated in artificial saliva for 30 min and then brushed in a toothbrushing machine (10 s brushing; total 2 min exposure to the product). After the toothbrush abrasion, the specimens were rinsed, dried and submitted to an erosive challenge (2 min; 1% citric acid; pH 3.6). This sequence was repeated 4 times, and the total enamel surface loss was calculated using indentation measurements before and after the brushing period. All groups presented progressive surface loss throughout the experiment; after 4 cycles, total surface loss values ranged from 0.11 µm (F+Sn3120-Gel) to 0.89 µm (F+Sn1260-TP). Regarding the total surface loss values (median; interquartile range), F-TP (0.54; 0.42–0.59) presented no significant differences compared to any of the other groups. F+Sn3500-TP (0.33; 0.30–0.40), F-TP + F+Oligopep-Gel (0.34; 0.29–0.42) and F+Sn3120-Gel (0.11; 0.09–0.15) presented lower surface loss than F+Oligopep-TP (0.75; 0.59–0.98), F+Sn1260-TP (0.89; 0.68–1.13) and F+Sn3440-TP (0.69; 0.66–0.78). Conclusion: Although some of the oral-care products containing stannous ions or oligopeptide-104 presented numerically lower SL values, they did not present significantly better protection than a regular fluoride toothpaste. The gels showed a general trend of better enamel protection against ETW.

Demographic, socioeconomic, and behavioral factors affecting patterns of tooth decay in the permanent dentition: Principal components and factor analyses

PubMed Central

Shaffer, John R.; Polk, Deborah E.; Feingold, Eleanor; Wang, Xiaojing; Cuenco, Karen T.; Weeks, Daniel E.; DeSensi, Rebecca S.; Weyant, Robert J.; Crout, Richard; McNeil, Daniel W.; Marazita, Mary L.

2012-01-01

Objectives Dental caries of the permanent dentition is a multi-factorial disease resulting from the complex interplay of endogenous and environmental risk factors. The disease is not easily quantified due to the innumerable possible combinations of carious lesions across individual tooth surfaces of the permanent dentition. Global measures of decay, such as the DMFS index (which was developed for surveillance applications), may not be optimal for studying the epidemiology of dental caries because they ignore the distinct patterns of decay across the dentition. We hypothesize that specific risk factors may manifest their effects on specific tooth surfaces leading to patterns of decay that can be identified and studied. In this study we utilized two statistical methods of extracting patterns of decay from surface-level caries data in order to create novel phenotypes with which to study the risk factors affecting dental caries. Methods Intra-oral dental examinations were performed on 1,068 participants aged 18 to 75 years to assess dental caries. The 128 tooth surfaces of the permanent dentition were scored as carious or not and used as input for principal components analysis (PCA) and factor analysis (FA), two methods of identifying underlying patterns without a priori knowledge of the patterns. Demographic (age, sex, birth year, race/ethnicity, and educational attainment), anthropometric (height, body mass index, waist circumference), endogenous (saliva flow), and environmental (tooth brushing frequency, home water source, and home water fluoride) risk factors were tested for association with the caries patterns identified by PCA and FA, as well as DMFS, for comparison. The ten strongest patterns (i.e., those that explain the most variation in the data set) extracted by PCA and FA were considered. Results The three strongest patterns identified by PCA reflected (i) global extent of decay (i.e., comparable to DMFS index), (ii) pit and fissure surface caries, and (iii) smooth surface caries, respectively. The two strongest patterns identified by FA corresponded to (i) pit and fissure surface caries and (ii) maxillary incisor caries. Age and birth year were significantly associated with several patterns of decay, including global decay/DMFS index. Sex, race, educational attainment, and tooth brushing were each associated with specific patterns of decay, but not with global decay/DMFS index. Conclusions Taken together, these results support the notion that caries experience is separable into patterns attributable to distinct risk factors. This study demonstrates the utility of such novel caries patterns as new outcomes for exploring the complex, multifactorial nature of dental caries. PMID:23106439

Demographic, socioeconomic, and behavioral factors affecting patterns of tooth decay in the permanent dentition: principal components and factor analyses.

PubMed

Shaffer, John R; Polk, Deborah E; Feingold, Eleanor; Wang, Xiaojing; Cuenco, Karen T; Weeks, Daniel E; DeSensi, Rebecca S; Weyant, Robert J; Crout, Richard; McNeil, Daniel W; Marazita, Mary L

2013-08-01

Dental caries of the permanent dentition is a multifactorial disease resulting from the complex interplay of endogenous and environmental risk factors. The disease is not easily quantitated due to the innumerable possible combinations of carious lesions across individual tooth surfaces of the permanent dentition. Global measures of decay, such as the DMFS index (which was developed for surveillance applications), may not be optimal for studying the epidemiology of dental caries because they ignore the distinct patterns of decay across the dentition. We hypothesize that specific risk factors may manifest their effects on specific tooth surfaces leading to patterns of decay that can be identified and studied. In this study, we utilized two statistical methods of extracting patterns of decay from surface-level caries data to create novel phenotypes with which to study the risk factors affecting dental caries. Intra-oral dental examinations were performed on 1068 participants aged 18-75 years to assess dental caries. The 128 tooth surfaces of the permanent dentition were scored as carious or not and used as input for principal components analysis (PCA) and factor analysis (FA), two methods of identifying underlying patterns without a priori knowledge of the patterns. Demographic (age, sex, birth year, race/ethnicity, and educational attainment), anthropometric (height, body mass index, waist circumference), endogenous (saliva flow), and environmental (tooth brushing frequency, home water source, and home water fluoride) risk factors were tested for association with the caries patterns identified by PCA and FA, as well as DMFS, for comparison. The ten strongest patterns (i.e. those that explain the most variation in the data set) extracted by PCA and FA were considered. The three strongest patterns identified by PCA reflected (i) global extent of decay (i.e. comparable to DMFS index), (ii) pit and fissure surface caries and (iii) smooth surface caries, respectively. The two strongest patterns identified by FA corresponded to (i) pit and fissure surface caries and (ii) maxillary incisor caries. Age and birth year were significantly associated with several patterns of decay, including global decay/DMFS index. Sex, race, educational attainment, and tooth brushing were each associated with specific patterns of decay, but not with global decay/DMFS index. Taken together, these results support the notion that caries experience is separable into patterns attributable to distinct risk factors. This study demonstrates the utility of such novel caries patterns as new outcomes for exploring the complex, multifactorial nature of dental caries. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Does the hybrid light source (LED/laser) influence temperature variation on the enamel surface during 35% hydrogen peroxide bleaching? A randomized clinical trial.

PubMed

de Freitas, Patricia Moreira; Menezes, Andressa Nery; da Mota, Ana Carolina Costa; Simões, Alyne; Mendes, Fausto Medeiros; Lago, Andrea Dias Neves; Ferreira, Leila Soares; Ramos-Oliveira, Thayanne Monteiro

2016-01-01

The present study investigated how a hybrid light source (LED/laser) influences temperature variation on the enamel surfaces during 35% hydrogen peroxide (HP) bleaching. Effects on the whitening effectiveness and tooth sensitivity were analyzed. Twenty-two volunteers were randomly assigned to two different treatments in a split-mouth experimental model: group 1 (control), 35% HP; group 2 (experimental), 35% HP + LED/laser. Color evaluation was performed before treatment, and 7 and 14 days after completion of bleaching, using a color shade scale. Tooth sensitivity was assessed using a visual analog scale (VAS; before, immediately, and 24 hours after bleaching). During the bleaching treatment, thermocouple channels positioned on the tooth surfaces recorded the temperature. Data on color and temperature changes were subjected to statistical analysis (α = 5%). Tooth sensitivity data were evaluated descriptively. Groups 1 and 2 showed mean temperatures (± standard deviation) of 30.7 ± 1.2 °C and 34.1 ± 1.3 °C, respectively. It was found that there were statistically significant differences between the groups, with group 2 showing higher mean variation (P < .0001). The highest temperature variation occurred for group 2, with an increase of 5.3 °C at the enamel surface. The color change results showed no differences in bleaching between the two treatment groups (P = .177). The variation of the average temperature during the treatments was not statistically associated with color variation (P = .079). Immediately after bleaching, it was found that 36.4% of the subjects in group 2 had mild to moderate sensitivity. In group 1, 45.5% showed moderate sensitivity. In both groups, the sensitivity ceased within 24 hours. Hybrid light source (LED/ laser) influences temperature variation on the enamel surface during 35% HP bleaching and is not related to greater tooth sensitivity.

Novel laser contact probe for periodontal treatment

NASA Astrophysics Data System (ADS)

Watanabe, Hisashi; Kataoka, Kenzo; Ishikawa, Isao

2001-04-01

Application of the erbium: YAG laser to periodontal treatment has been attempted and preferable results have been reported for calculus removal, vaporization of granulation tissue, periodontal pocket sterilization and so on. However, it has been difficult to reach and treat some conditions involving complex root morphology and furcated rots with conventional probes. The new broom probe was designed and tested to overcome these obstacles. The probe was made of 20 super-fine optical fibers bound into a broom shape. The experiments were carried out to evaluate the destructive power of a single fiber and to examine the morphology of tissue destruction and the accessibility to a bifurcated root of a human tooth using the broom probe. The Er:YAG laser prototype was used. A flat specimen plate was made by cutting the root of a cow tooth and then attached to an electrically operated table and irradiated under various conditions. The specimens were examined with both an optical and scanning electron microscope. The irradiated surfaces were also examined with a roughness meter. An irradiation applied with a single fiber with an energy level of 1 to 1.5 mJ at its tip results in a destruction depth of 3 to 24 micrometers . The optimum conditions for the fibers of this probe was 1.0 mJ at 10 pps and a scanning speed of 100 mm/min. No part of the tooth surface remained un-irradiated after using the broom probe to cover the surface 5 times parallel to the tooth axis and then five times at a 30 degree angle to the previous irradiation at a power of 20 mJ at 10 pps. Also curved and irregular surface were destroyed to a maximum depth of 19 micrometers . In conclusion, these results suggest that the broom probe would be applicable for periodontal laser treatments even if the tooth surface has a complex and irregular shape.

Can in vivo surface dental enamelmicrobiopsies be used to measure remote lead exposure?

PubMed

Olympio, Kelly Polido Kaneshiro; Huila, Manuel Fernando Gonzalez; de Almeida Baldini Cardoso, Cristiane; da Silva Ferreira, Ana Paula Sacone; Ortiz, Adrielly Garcia; Toma, Henrique Eisi; da Silva, Ricardo Henrique Alves; Luz, Maciel Santos; Cardoso, Maria Regina Alves; Kelmer, Gislayne Aparecida Rodrigues; de Oliveira, Pedro Vitoriano; Bechara, Etelvino José Henriques; Günther, Wanda Maria Risso; Buzalaf, Marília Afonso Rabelo

2018-04-01

Measuring lead in the surface dental enamel (SDE) using biopsies is a rapid, safe, and painless procedure. The dental enamel lead levels (DELLs) decrease from the outermost superficial layer to the inner layer of dental enamel, which becomes crucial for the biopsy depth (BD) measurement. However, whether the origin of lead found in SDE is fully endogenous is not yet established. There is also controversy about the biopsy protocol. The aims of this study were to investigate if DELLs are altered by extrinsic contamination (A) and to evaluate the real geometric figure formed by the erosion provoked by biopsy procedure and the respective BD in SDE (B). To accomplish the aim A, lead from 90 bovine incisor crowns lead was determined by graphite furnace atomic absorption spectrometer as a function of exposure time and lead concentration. Two biopsies were performed in each tooth, before and after lead exposure. Six 15-tooth groups differed by exposure time (1 or 30 min) and lead concentrations (A. 0 mg/L-placebo, B. 0.01 mg/L-standard for drinking water, or C. 0.06 mg/L-concentration found in contaminated groundwater). Phosphorus was determined by an inductively coupled plasm optical emission spectrometer to quantify the enamel removed. To compare intakes/losses of lead in SDE among the groups, values of DELL differences between before and after lead exposure were compared by ANOVA (p < 0.05). To attain the objective B, one extracted human permanent tooth was studied by confocal Raman microscopy. Lead measurements and the surface profile were determined. There was no difference in DELL among the groups (p = 0.964). The biopsy bottom surface area, analyzed by microscopy, showed an irregular area, with regions of peaks and valleys, where areas with depth ranging from 0.2 (peaks) to 1.8 μm (valleys) (± 0.1 μm) could be found. BD carried out in vivo is commonly calculated using the cylinder height formula. The real BD was shown to be very similar to already published data. In conclusion, the SDE of erupted teeth does not seem to be susceptible to environmental lead intake, being thus reliable to measure remote exposures to lead.

Mechanisms and causes of wear in tooth enamel: implications for hominin diets.

PubMed

Lucas, Peter W; Omar, Ridwaan; Al-Fadhalah, Khaled; Almusallam, Abdulwahab S; Henry, Amanda G; Michael, Shaji; Thai, Lidia Arockia; Watzke, Jörg; Strait, David S; Atkins, Anthony G

2013-03-06

The wear of teeth is a major factor limiting mammalian lifespans in the wild. One method of describing worn surfaces, dental microwear texture analysis, has proved powerful for reconstructing the diets of extinct vertebrates, but has yielded unexpected results in early hominins. In particular, although australopiths exhibit derived craniodental features interpreted as adaptations for eating hard foods, most do not exhibit microwear signals indicative of this diet. However, no experiments have yet demonstrated the fundamental mechanisms and causes of this wear. Here, we report nanowear experiments where individual dust particles, phytoliths and enamel chips were slid across a flat enamel surface. Microwear features produced were influenced strongly by interacting mechanical properties and particle geometry. Quartz dust was a rigid abrasive, capable of fracturing and removing enamel pieces. By contrast, phytoliths and enamel chips deformed during sliding, forming U-shaped grooves or flat troughs in enamel, without tissue loss. Other plant tissues seem too soft to mark enamel, acting as particle transporters. We conclude that dust has overwhelming importance as a wear agent and that dietary signals preserved in dental microwear are indirect. Nanowear studies should resolve controversies over adaptive trends in mammals like enamel thickening or hypsodonty that delay functional dental loss.

Comparison of risk factors for tooth loss between professional drivers and white-collar workers: an internet survey.

PubMed

Suzuki, Seitaro; Yoshino, Koichi; Takayanagi, Atsushi; Ishizuka, Yoichi; Satou, Ryouichi; Kamijo, Hideyuki; Sugihara, Naoki

2016-06-10

This cross-sectional study was conducted to examine tooth loss and associated factors among professional drivers and white-collar workers. The participants were recruited by applying screening procedures to a pool of Japanese registrants in an online database. The participants were asked to complete a self-reported questionnaire. A total of 592 professional drivers and 328 white-collar workers (male, aged 30 to 69 years) were analyzed. A multiple logistic regression analysis was performed to identify differences between professional drivers and white-collar workers. The results showed that professional drivers had fewer teeth than white-collar workers (odds ratio [OR], 1.74; 95% confidence interval [95% CI], 1.150-2.625). Moreover, a second multiple logistic regression analysis revealed that several factors were associated with the number of teeth among professional drivers: diabetes mellitus (OR, 2.68; 95% CI, 1.388-5.173), duration of brushing teeth (OR, 1.66; 95% CI, 1.066-2.572), frequency of eating breakfast (OR, 2.23; 95% CI, 1.416-3.513), frequency of eating out (OR, 1.70; 95% CI, 1.086-2.671) and smoking status (OR, 2.88; 95% CI, 1.388-5.964). These findings suggest that the lifestyles of professional drivers could be related to not only their general health status, but also tooth loss.

Abfraction lesions: etiology, diagnosis, and treatment options

PubMed Central

Nascimento, Marcelle M; Dilbone, Deborah A; Pereira, Patricia NR; Duarte, Wagner R; Geraldeli, Saulo; Delgado, Alex J

2016-01-01

Abfraction is a type of noncarious cervical lesion (NCCL) characterized by loss of tooth tissues with different clinical appearances. Evidence supports that abfraction lesions, as any NCCLs, have a multifactorial etiology. Particularly, the cervical wear of abfraction can occur as a result of normal and abnormal tooth function and may also be accompanied by pathological wear, such as abrasion and erosion. The interaction between chemical, biological, and behavioral factors is critical and helps to explain why some individuals exhibit more than one type of cervical wear mechanism than others. In an era of personalized dentistry, patient risk factors for NCCLs must be identified and addressed before any treatment is performed. Marked variations exist in dental practice concerning the diagnosis and management of these lesions. The lack of understanding about the prognosis of these lesions with or without intervention may be a major contributor to variations in dentists’ management decisions. This review focuses on the current knowledge and available treatment strategies for abfraction lesions. By recognizing that progressive changes in the cervical area of the tooth are part of a physiologically dynamic process that occurs with aging, premature and unnecessary intervention can be avoided. In cases of asymptomatic teeth, where tooth vitality and function are not compromised, abfraction lesions should be monitored for at least 6 months before any invasive procedure is planned. In cases of abfraction associated with gingival recession, a combined restorative-surgical approach may be performed. Restorative intervention and occlusal adjustment are not indicated as treatment options to prevent further tooth loss or progression of abfraction. The clinical decision to restore abfraction lesions may be based on the need to replace form and function or to relieve hypersensitivity of severely compromised teeth or for esthetic reasons. PMID:27217799

Regular nicotine intake increased tooth movement velocity, osteoclastogenesis and orthodontically induced dental root resorptions in a rat model

PubMed Central

Kirschneck, Christian; Maurer, Michael; Wolf, Michael; Reicheneder, Claudia; Proff, Peter

2017-01-01

Orthodontic forces have been reported to significantly increase nicotine-induced periodontal bone loss. At present, however, it is unknown, which further (side) effects can be expected during orthodontic treatment at a nicotine exposure corresponding to that of an average European smoker. 63 male Fischer344 rats were randomized in three consecutive experiments of 21 animals each (A/B/C) to 3 experimental groups (7 rats, 1/2/3): (A) cone-beam-computed tomography (CBCT); (B) histology/serology; (C) reverse-transcription quantitative real-time polymerase chain reaction (RT-qPCR)/cotinine serology—(1) control; (2) orthodontic tooth movement (OTM) of the first and second upper left molar (NiTi closed coil spring, 0.25 N); (3) OTM with 1.89 mg·kg−1 per day s.c. of L(−)-nicotine. After 14 days of OTM, serum cotinine and IL-6 concentration as well as orthodontically induced inflammatory root resorption (OIIRR), osteoclast activity (histology), orthodontic tooth movement velocity (CBCT, within 14 and 28 days of OTM) and relative gene expression of known inflammatory and osteoclast markers were quantified in the dental-periodontal tissue (RT–qPCR). Animals exposed to nicotine showed significantly heightened serum cotinine and IL-6 levels corresponding to those of regular European smokers. Both the extent of root resorption, osteoclast activity, orthodontic tooth movement and gene expression of inflammatory and osteoclast markers were significantly increased compared to controls with and without OTM under the influence of nicotine. We conclude that apart from increased periodontal bone loss, a progression of dental root resorption and accelerated orthodontic tooth movement are to be anticipated during orthodontic therapy, if nicotine consumption is present. Thus patients should be informed about these risks and the necessity of nicotine abstinence during treatment. PMID:28960194

Fate of the Molar Dental Lamina in the Monophyodont Mouse

PubMed Central

Dosedělová, Hana; Dumková, Jana; Lesot, Hervé; Glocová, Kristýna; Kunová, Michaela; Tucker, Abigail S.; Veselá, Iva; Krejčí, Pavel; Tichý, František; Hampl, Aleš; Buchtová, Marcela

2015-01-01

The successional dental lamina (SDL) plays an essential role in the development of replacement teeth in diphyodont and polyphyodont animals. A morphologically similar structure, the rudimental successional dental lamina (RSDL), has been described in monophyodont (only one tooth generation) lizards on the lingual side of the developing functional tooth. This rudimentary lamina regresses, which has been proposed to play a role in preventing the formation of future generations of teeth. A similar rudimentary lingual structure has been reported associated with the first molar in the monophyodont mouse, and we show that this structure is common to all murine molars. Intriguingly, a lingual lamina is also observed on the non-replacing molars of other diphyodont mammals (pig and hedgehog), initially appearing very similar to the successional dental lamina on the replacing teeth. We have analyzed the morphological as well as ultrastructural changes that occur during the development and loss of this molar lamina in the mouse, from its initiation at late embryonic stages to its disappearance at postnatal stages. We show that loss appears to be driven by a reduction in cell proliferation, down-regulation of the progenitor marker Sox2, with only a small number of cells undergoing programmed cell death. The lingual lamina was associated with the dental stalk, a short epithelial connection between the tooth germ and the oral epithelium. The dental stalk remained in contact with the oral epithelium throughout tooth development up to eruption when connective tissue and numerous capillaries progressively invaded the dental stalk. The buccal side of the dental stalk underwent keratinisation and became part of the gingival epithelium, while most of the lingual cells underwent programmed cell death and the tissue directly above the erupting tooth was shed into the oral cavity. PMID:26010446

Guide for Inspection of Coatings Applied to Hydraulic Structures.

DTIC Science & Technology

1986-04-01

observed, many specifiers provide that the surfaces must be sweep blasted to provide a " tooth " before topcoating, or wiped with some strong solvent. CW...termed anchor pattern, profile, or " tooth ," and is essentially a pattern of peaks and valleys on the steel surface. This pattern is obtained by abrasive...situation, a sealer must be applied. Blushing Blushing is the hazing or whitening of the finish as a result of the absorption and "" retention of

New Methods for Improved Double Circular-Arc Helical Gears

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Lu, Jian

1997-01-01

The authors have extended the application of double circular-arc helical gears for internal gear drives. The geometry of the pinion and gear tooth surfaces has been determined. The influence of errors of alignment on the transmission errors and the shift of the bearing contact have been investigated. Application of a predesigned parabolic function for the reduction of transmission errors was proposed. Methods of grinding of the pinion-gear tooth surfaces by a disk-shaped tool and a grinding worm were proposed.

Hollow-core photonic-crystal fibres for laser dentistry.

PubMed

Konorov, Stanislav O; Mitrokhin, Vladimir P; Fedotov, Andrei B; Sidorov-Biryukov, Dmitrii A; Beloglazov, Valentin I; Skibina, Nina B; Wintner, Ernst; Scalora, Michael; Zheltikov, Aleksei M

2004-04-07

Hollow-core photonic-crystal fibres (PCFs) for the delivery of high-fluence laser radiation capable of ablating tooth enamel are developed. Sequences of picosecond pulses of 1.06 microm Nd:YAG-laser radiation with a total energy of about 2 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 microm and are focused on a tooth surface in vitro to ablate dental tissue. The hollow-core PCF is shown to support the single-fundamental-mode regime for 1.06 microm laser radiation, serving as a spatial filter and allowing the laser beam quality to be substantially improved. The same fibre is used to transmit emission from plasmas produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.

Modelling of micromachining of human tooth enamel by erbium laser radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belikov, A V; Skrypnik, A V; Shatilova, K V

We consider a 3D cellular model of human tooth enamel and a photomechanical cellular model of enamel ablation by erbium laser radiation, taking into account the structural peculiarities of enamel, energy distribution in the laser beam cross section and attenuation of laser energy in biological tissue. The surface area of the texture in enamel is calculated after its micromachining by erbium laser radiation. The influence of the surface area on the bond strength of enamel with dental filling materials is discussed. A good correlation between the computer simulation of the total work of adhesion and experimentally measured bond strength betweenmore » the dental filling material and the tooth enamel after its micromachining by means of YAG : Er laser radiation is attained. (laser biophotonics)« less

Early Orthodontic Tooth Movement into Regenerative Bony Defects: A Case Report.

PubMed

Tsai, Hui-Chen; Yao, Chung-Chen Jane; Wong, Man-Ying

Early orthodontic tooth movement following regenerative surgery is controversial. In this case, during protraction of the maxillary right first premolar to substitute for the long-term missing maxillary right canine, Bio-Oss and Bio-Gide were used for lateral ridge augmentation at the area of the maxillary right lateral incisor and to cover the denuded surface at the buccal side of the first premolar. Orthodontic tooth movement (OTM) commenced 2 weeks after regenerative surgery. After 8 months, new bone formation was observed on the root surface of the first premolar during implant surgery. A cone beam computed tomography scan taken 1.5 years postsurgery revealed good maintenance of regenerative bone at the same site. This satisfactory outcome of early OTM following regenerative surgery suggests biomechanical stimulation may not jeopardize the regenerative effect.

Understanding wear in dentistry.

PubMed

Mair, L H

1999-01-01

Tooth wear is an increasing problem in dentistry. Traditionally, it has been divided into three categories: abrasion, attrition, and erosion. However, most clinical cases of tooth wear involve more than one of these processes. It is often easier to make a diagnosis by looking for the signs of the fundamental wear processes rather than trying to categorize the individual case. Wear can be caused by direct surface-to-surface wear, an intervening slurry, or a corrosive environment. Wear occurs during mastication, but also at other times, often at night. Although it may be possible to institute a preventive regimen, this will not always help the patient if his or her prime concern is esthetics. The same processes that cause tooth wear will cause wear to restorative materials. To diagnose and prevent wear, its processes must be understood.

Sensor mount assemblies and sensor assemblies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, David H

2012-04-10

Sensor mount assemblies and sensor assemblies are provided. In an embodiment, by way of example only, a sensor mount assembly includes a busbar, a main body, a backing surface, and a first finger. The busbar has a first end and a second end. The main body is overmolded onto the busbar. The backing surface extends radially outwardly relative to the main body. The first finger extends axially from the backing surface, and the first finger has a first end, a second end, and a tooth. The first end of the first finger is disposed on the backing surface, and themore » tooth is formed on the second end of the first finger.« less

Gear Crack Propagation Path Studies-- Guidelines Developed for Ultrasafe Design

NASA Technical Reports Server (NTRS)

Lewicki, David G.

2002-01-01

Effective gear designs balance strength, durability, reliability, size, weight, and cost. However, unexpected gear failures may occur even with adequate gear tooth design. To design an extremely safe system, the designer must ask and address the question "What happens when a failure occurs?" With regard to gear-tooth bending fatigue, tooth or rim fractures may occur. For aircraft, a crack that propagated through a rim would be catastrophic, leading to the disengagement of a rotor or propeller, the loss of an aircraft, and possible fatalities. This failure mode should be avoided. However, a crack that propagated through a tooth might or might not be catastrophic, depending on the design and operating conditions. Also, early warning of this failure mode might be possible because of advances in modern diagnostic systems. An analysis was performed at the NASA Glenn Research Center to develop design guidelines to prevent catastrophic rim fracture failure modes in the event of gear-tooth bending fatigue. The finite element method was used with principles of linear elastic fracture mechanics. Crack propagation paths were predicted for a variety of gear tooth and rim configurations. The effects of rim and web thicknesses, initial crack locations, and gear-tooth geometry factors such as diametral pitch, number of teeth, pitch radius, and tooth pressure angle were considered. Design maps of tooth and rim fracture modes, including the effects of gear geometry, applied load, crack size, and material properties were developed. The occurrence of rim fractures significantly increased as the backup ratio (rim thickness divided by tooth height) decreased. The occurrence of rim fractures also increased as the initial crack location was moved down the root of the tooth. Increased rim and web compliance increased the occurrence of rim fractures. For gears with constant-pitch radii, coarser-pitch teeth increased the occurrence of tooth fractures over rim fractures. Also, 25 degree pressure angle teeth increased the occurrence of tooth fractures over rim fractures in comparison to 20 pressure angle teeth. For gears with a constant number of teeth or for gears with constant diametral pitch, varying size had little or no effect on crack propagation paths.

Replacement of missing teeth with fiber-reinforced composite FPDs: clinical protocol.

PubMed

Bouillaguet, Serge; Schütt, Andrea; Marin, Isabelle; Etechami, Leila; Di Salvo, Giancarlo; Krejci, Ivo

2003-04-01

The concept of minimally invasive preparation protocols has resulted in reduced loss of critical tooth structures and maintenance of optimal strength, form, and aesthetics. While various treatment options have been described for single-tooth replacement, fiber-reinforced composite (FRC) fixed partial dentures (FPDs) provide a viable treatment alternative with proven mechanical properties, aesthetics, and function. This article presents several clinical scenarios in which minimally invasive adhesive FRC FPDs are provided to deliver enhanced predictability, strength, and durability.

Tooth wear and loss: symptomatological and rehabilitating treatments.

PubMed

Hotta, T H; Nunes, L J; Quatrini, A H; Bataglion, C; Nonaka, T; Bezzon, O L

2000-01-01

The authors report a clinical case that presented tooth wear and absence, with painful muscular and articular symptomatology, and also alteration in deglutition, mastication and speech. The clinical procedures used were re-establishment of vertical dimension of occlusion, mandibular centric relations, and occlusal contacts through therapeutic removable partial dentures. The condyle position was analyzed in habitual occlusion and in occlusion with dentures, through transcranial radiographs of the temporomandibular joints. Oral rehabilitation was achieved with dental restoration and removable partial dentures.

The influence of a novel in-office tooth whitening procedure using an Er,Cr:YSGG laser on enamel surface morphology.

PubMed

Dionysopoulos, Dimitrios; Strakas, Dimitrios; Koliniotou-Koumpia, Eugenia

2015-08-01

The purpose of this in vitro study was to evaluate the influence of a novel in-office tooth whitening procedure using Er,Cr:YSGG laser radiation on bovine enamel. Forty-eight enamel specimens were prepared from bovine canines and divided into four groups: Group 1 specimens (control) received no whitening treatment; Group 2 received whitening treatment with an at-home whitening agent (22% carbamide peroxide) for 7 days; Group 3 received whitening treatment with a novel in-office whitening agent (35% H(2)O(2)); Group 4 received the same in-office whitening therapy with Group 3 using Er,Cr:YSGG laser in order to accelerate the whitening procedure. The specimens were stored for 10 days after the whitening treatment in artificial saliva. Vickers hardness was determined using a microhardness tester and surface roughness was evaluated using a VSI microscope. Three specimens of each experimental group were examined under SEM and the mineral composition of the specimens was evaluated using EDS. Data were statistically analyzed using one-way ANOVA, Tukey's post-hoc test, Wilcoxon signed rank and Kruskal-Wallis tests (a = 0.05). The surface microhardness of the enamel was reduced after the in-office whitening treatments (P< 0.05), but not influenced after the at-home whitening treatment (P> 0.05). Moreover, the surface roughness was not significantly changed after tooth whitening. EDS analysis did not show alterations in the enamel mineral composition, while SEM observations indicated changes in the surface morphology, especially after in-office tooth whitening (P< 0.05). The laser-assisted whitening treatment with Er,Cr:YSGG laser did not affect the alterations in enamel surface compared with the conventional in-office whitening technique. © 2015 Wiley Periodicals, Inc.

A comparison of roughness parameters and friction coefficients of aesthetic archwires.

PubMed

Rudge, Philippa; Sherriff, Martyn; Bister, Dirk

2015-02-01

Compare surface roughness of 'aesthetic' nickel-titanium (NiTi) archwires with their dynamic frictional properties. Archwires investigated were: four fully coated tooth coloured [Forestadent: Biocosmetic (FB) and Titanol Cosmetic (FT); TOC Tooth Tone (TT); and Hawley Russell Coated Superelastic NiTi (HRC)]; two partially coated tooth coloured [DB Euroline Microcoated (DB) and TP Aesthetic NiTi (TP)]; two rhodium coated [TOC Sentalloy (TS) and Hawley Russell Rhodium Coated Superelastic NiTi (HRR)]; and two controls: stainless steel [Forestadent Steel (FS)] and NiTi archwire [Forestadent Titanol Superelastic (FN)]. Surface roughness [profilometry (Rugosurf)] was compared with frictional coefficients for archwire/bracket/ligature combinations (n = 10). Analysis of variance, Sidak's multiple comparison of means, and Spearman's correlation coefficient were used for analysis. Roughness coefficients were from low to high: FB; FN; TT; FS; TS; HRR; FT; DB; TP; HRC. Friction coefficients were from low to high: TP; FS; FN; HRR; FT; DB; FB; HRC; TS; TT. Coated archwires generally exhibited higher friction than uncoated controls. TP had the lowest friction but this was not statistically significant (P < 0.05). Friction of tooth coloured coated archwires were significantly different for some wires. Spearman's correlation did not demonstrate consistency between surface roughness (R a) and dynamic friction. Aesthetic archwires investigated had either low surface roughness or low frictional resistance but not both properties simultaneously. Causes for friction are likely to be multifactorial and do not appear to be solely determined by surface roughness (measured by profilometry). For selecting the most appropriate aligning archwire, both surface roughness and frictional resistance need to be considered. © The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Treatment of Necrotic Teeth by Apical Revascularization: Meta-analysis.

PubMed

He, Ling; Zhong, Juan; Gong, Qimei; Kim, Sahng G; Zeichner, Samuel J; Xiang, Lusai; Ye, Ling; Zhou, Xuedong; Zheng, Jinxuan; Liu, Yongxing; Guan, Chenyu; Cheng, Bin; Ling, Junqi; Mao, Jeremy J

2017-10-24

Each year ~5.4 million children and adolescents in the United States suffer from dental infections, leading to pulp necrosis, arrested tooth-root development and tooth loss. Apical revascularization, adopted by the American Dental Association for its perceived ability to enable postoperative tooth-root growth, is being accepted worldwide. The objective of the present study is to perform a meta-analysis on apical revascularization. Literature search yielded 22 studies following PRISMA with pre-defined inclusion and exclusion criteria. Intraclass correlation coefficient was calculated to account for inter-examiner variation. Following apical revascularization with 6- to 66-month recalls, root apices remained open in 13.9% cases (types I), whereas apical calcification bridge formed in 47.2% (type II) and apical closure (type III) in 38.9% cases. Tooth-root lengths lacked significant postoperative gain among all subjects (p = 0.3472) or in subgroups. Root-dentin area showed significant increases in type III, but not in types I or II cases. Root apices narrowed significantly in types II and III, but not in type I patients. Thus, apical revascularization facilitates tooth-root development but lacks consistency in promoting root lengthening, widening or apical closure. Post-operative tooth-root development in immature permanent teeth represents a generalized challenge to regenerate diseased pediatric tissues that must grow to avoid organ defects.

[Destructive and protective factors in the development of tooth-wear].

PubMed

Jász, Máté; Varga, Gábor; Tóth, Zsuzsanna

2006-12-01

The experience of the past decade proves that tooth wear occurs in an increasing number of cases in general dental practice. Tooth wear may have physical (abrasion and attrition) and/or chemical (erosion) origin. The primary physical causes are inadequate dental hygienic activities, bad oral habits or occupational harm. As for dental erosion, it is accelerated by the highly erosive foods and drinks produced and sold in the past decades, and the number of cases is also boosted by the fact that bulimia, anorexia nervosa and gastro-oesophageal reflux disease prevalence have become more common. The most important defensive factor against tooth wear is saliva, which protects teeth from the effect of acids. Tertiary dentin formation plays an important role in the protection of the pulp. Ideally, destructive and protective factors are in balance. Both an increase in the destructive forces, and the insufficiency of defense factors result in the disturbance of the equilibrium. This results in tooth-wear, which means an irreversible loss of dental hard tissue. The rehabilitation of the lost tooth material is often very difficult, irrespectively of whether it is needed because of functional or esthetic causes. For that reason, the dentist should carry out primary and secondary dental care and prevention more often, i.e. dental recall is indispensable every 4-6 months.

Increasing the amount of corticotomy does not affect orthodontic tooth movement or root resorption, but accelerates alveolar bone resorption in rats.

PubMed

Kurohama, Takeshi; Hotokezaka, Hitoshi; Hashimoto, Megumi; Tajima, Takako; Arita, Kotaro; Kondo, Takanobu; Ino, Airi; Yoshida, Noriaki

2017-06-01

The purpose of this study was to evaluate the relationships among the volume of bone cut during corticotomy, amount of tooth movement, volume of root resorption, and volume of the resultant alveolar bone resorption after tooth movement. Ten-week-old female Wistar rats were distributed into the corticotomy groups and a control group that underwent sham corticotomy. Two experiments employing two different orthodontic forces (10 or 25g) and experimental periods (14 or 21 days) were performed. The volumes of the bone cut by corticotomy were 0.1, 1.0, and 1.7mm3 in the 25g groups, and 1.0 and 1.7mm3 in the 10g groups. Nickel-titanium closed-coil springs were set on the maxillary left first molars to induce mesial movement. After orthodontic tooth movement, the amount of tooth movement, volume of root resorption, and volume of alveolar bone resorption were measured. Despite differences in the volume of bone cut among the different corticotomy groups, there were not significant differences in the amount of tooth movement and volume of root resorption between the control group and any of the corticotomy groups. However, higher volume of bone cut during corticotomy was significantly related to the decreased alveolar bone volume-in particular, to the reduced height of the alveolar bone crest after tooth movement. The volume of the alveolar bone cut during corticotomy does not affect tooth movement or root resorption in 10-week-old female Wistar rats; however, it may increase alveolar bone loss after tooth movement. © The Author 2016. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com

The In vitro Evaluation of the effect of xyliwhite, probiotic, and the conventional toothpastes on the enamel roughness and microhardness.

PubMed

Maden, E Arat; Altun, C; Polat, G Guven; Basak, F

2018-03-01

The aim of this study was to evaluate the effect of fluoride, Xylitol, Probiotic, and Whitening toothpastes on the permanent teeth enamel roughness and microhardness. One hundred and twenty teeth were randomly divided into 2 groups, each group having 60 samples. G1: The group in which enamel roughness was examined (n = 60). G2: The group in which enamel microhardness was examined (n = 60). Then, these groups were randomly divided into 4 groups among themselves (n = 15). Each group was brushed using four different toothpastes for 1 week with a battery-powered toothbrush in the morning and evening for 2 min. Vicker's hardness tester was used to measure the changes in microhardness, and the profilometer was used to measure the changes in surface roughness. No statistically significant differences were found on surface roughness and microhardness values measured after tooth brushing process in group brushed with Colgate MaxFresh toothpaste (P > 0.01). Statistically significant decrease was observed on Vicker's hardness values measured after tooth brushing process in groups brushed with Ipana White Power Carbonate toothpaste, Xyliwhite Toothpaste Gel, and Periobiotic Probiotic Toothpaste (P < 0.01). Statistically significant increase was observed on surface roughness values in groups brushed with Ipana White Power Carbonate toothpaste, Xyliwhite Toothpaste Gel, Periobiotic Probiotic Toothpaste (P < 0.01). As a result, Colgate MaxFresh abrasive-free toothpaste with fluoride has no effect on permanent tooth enamel surface roughness and microhardness. Xyliwhite, Periobiotic, and Ipana White Power Carbonate-containing abrasive toothpastes led to changes negatively on permanent tooth enamel surface roughness and microhardness.

Near-IR Image-Guided Laser Ablation of Demineralization on Tooth Occlusal Surfaces

PubMed Central

Tom, Henry; Chan, Kenneth H.; Darling, Cynthia L.; Fried, Daniel

2016-01-01

Introduction Studies have shown that reflectance images at near-IR wavelengths coincident with higher water absorption are well-suited for image-guided laser ablation of carious lesions since the contrast between sound and demineralized enamel is extremely high and interference from stains is minimized. The objective of this study was to demonstrate that near-IR reflectance images taken at a wavelength range of 1,500–1,700 nm can be used to guide a 9.3 μm CO2 laser for the selective ablation of early demineralization on tooth occlusal surfaces. Methods The occlusal surfaces of ten sound human molars were used in this in vitro study. Shallow simulated caries lesions with random patterns and varying depth and position were produced on tooth occlusal surfaces. Sequential near-IR reflectance images at 1,500–1,700 nm were used to guide the laser for the selective removal of the demineralized enamel. Digital microscopy and polarization sensitive optical coherence tomography (PS-OCT) were used to assess selectivity. Results Images taken before and after lesion removal suggest that the demineralized areas were removed with high selectivity. Although the estimated volume of tissue ablated was typically higher than the initial lesion volume measured with PS-OCT, the volume of enamel removed by the laser correlated well with the initial lesion volume. Conclusion Sequential near-IR reflectance images at 1,500–1,700 nm can be used to guide a 9.3 μm CO2 laser for the selective ablation of early demineralization on tooth occlusal surfaces. PMID:26763111

Loss of teeth and enamel in tetrapods: fossil record, genetic data and morphological adaptations

PubMed Central

Davit-Béal, Tiphaine; Tucker, Abigail S; Sire, Jean-Yves

2009-01-01

Since their recruitment in the oral cavity, approximately 450 million years ago, teeth have been subjected to strong selective constraints due to the crucial role that they play in species survival. It is therefore quite surprising that the ability to develop functional teeth has subsequently been lost several times, independently, in various lineages. In this review, we concentrate our attention on tetrapods, the only vertebrate lineage in which several clades lack functional teeth from birth to adulthood. Indeed, in other lineages, teeth can be absent in adults but be functionally present in larvae and juveniles, can be absent in the oral cavity but exist in the pharyngeal region, or can develop on the upper jaw but be absent on the lower jaw. Here, we analyse the current data on toothless (edentate) tetrapod taxa, including information available on enamel-less species. Firstly, we provide an analysis of the dispersed and fragmentary morphological data published on the various living taxa concerned (and their extinct relatives) with the aim of tracing the origin of tooth or enamel loss, i.e. toads in Lissamphibia, turtles and birds in Sauropsida, and baleen whales, pangolins, anteaters, sloths, armadillos and aardvark in Mammalia. Secondly, we present current hypotheses on the genetic basis of tooth loss in the chicken and thirdly, we try to answer the question of how these taxa have survived tooth loss given the crucial importance of this tool. The loss of teeth (or only enamel) in all of these taxa was not lethal because it was always preceded in evolution by the pre-adaptation of a secondary tool (beak, baleens, elongated adhesive tongues or hypselodonty) useful for improving efficiency in food uptake. The positive selection of such secondary tools would have led to relaxed functional constraints on teeth and would have later compensated for the loss of teeth. These hypotheses raise numerous questions that will hopefully be answered in the near future. PMID:19422426

Rsk2, the Kinase Mutated in Coffin-Lowry Syndrome, Controls Cementum Formation.

PubMed

Koehne, T; Jeschke, A; Petermann, F; Seitz, S; Neven, M; Peters, S; Luther, J; Schweizer, M; Schinke, T; Kahl-Nieke, B; Amling, M; David, J-P

2016-07-01

The ribosomal S6 kinase RSK2 is essential for osteoblast function, and inactivating mutations of RSK2 cause osteopenia in humans with Coffin-Lowry syndrome (CLS). Alveolar bone loss and premature tooth exfoliation are also consistently reported symptoms in CLS patients; however, the pathophysiologic mechanisms are unclear. Therefore, aiming to identify the functional relevance of Rsk2 for tooth development, we analyzed Rsk2-deficient mice. Here, we show that Rsk2 is a critical regulator of cementoblast function. Immunohistochemistry, histology, micro-computed tomography imaging, quantitative backscattered electron imaging, and in vitro assays revealed that Rsk2 is activated in cementoblasts and is necessary for proper acellular cementum formation. Cementum hypoplasia that is observed in Rsk2-deficient mice causes detachment and disorganization of the periodontal ligament and was associated with significant alveolar bone loss with age. Moreover, Rsk2-deficient mice display hypomineralization of cellular cementum with accumulation of nonmineralized cementoid. In agreement, treatment of the cementoblast cell line OCCM-30 with a Rsk inhibitor reduces formation of mineralization nodules and decreases the expression of cementum markers. Western blot analyses based on antibodies against Rsk1, Rsk2, and an activated form of the 2 kinases confirmed that Rsk2 is expressed and activated in differentiating OCCM-30 cells. To discriminate between periodontal bone loss and systemic bone loss, we additionally crossed Rsk2-deficient mice with transgenic mice overexpressing the osteoanabolic transcription factor Fra1. Fra1 overexpression clearly increases systemic bone volume in Rsk2-deficient mice but does not protect from alveolar bone loss. Our results indicate that cell autonomous cementum defects are causing early tooth loss in CLS patients. Moreover, we identify Rsk2 as a nonredundant regulator of cementum homeostasis, alveolar bone maintenance, and periodontal health, with all these features being independent of Rsk2 function in systemic bone formation. © International & American Associations for Dental Research 2016.

A study of the periodontal state of a late Medieval United Kingdom population.

PubMed

Gonçalves, Pedro César Gaspar; Griffiths, Gareth; Rawlinson, Andrew

2015-12-01

To study the severity of bone loss in a Medieval UK population, and compare this with other ancient UK populations from different time periods. Skulls from a burial site in York (XI-XV century) were investigated. Skulls with a minimum of 17 teeth were included and were divided from childhood into five age groups. Direct measurements from the cement enamel junction (CEJ) to the alveolar crest (AC) were undertaken at six points around each tooth with a UNC 15 probe. The mean bone loss was calculated for each tooth type. Seventy five skulls were included in the study (12-60 years of age). Bone loss was found to increase with age, but stabilized in older individuals (>45 years). The mean CEJ-AC distance varied from 2.1mm in the youngest group to a maximum of 4.1mm in 36-45 year olds. Results were compared with a Roman-British population (Whittaker et al., 1982) where comparable values for mean bone loss were 2.2mm and 5.4mm respectively, and a population of XVIII century Londoners (Whittaker et al., 1998) where bone loss of 1.1mm and 4.0mm was reported for the youngest and oldest age groups respectively. Measuring the CEJ-AC distance in dried skulls from ancient populations may be used as a proxy for the levels of periodontal disease irrespective of tooth wear. The findings from the current study suggest that the severity of periodontitis as determined by measurements of alveolar bone loss on dried skulls from this ancient population, seems to have declined in the United Kingdom from the III-V century to XVIII century. This may be due to changes in environmental factors including living conditions and diet, together with individual characteristics including systemic illness and genetic make up. Copyright © 2015. Published by Elsevier Ltd.

Launch Lock Assemblies with Reduced Preload and Spacecraft Isolation Systems Including the Same

NASA Technical Reports Server (NTRS)

Barber, Tim Daniel (Inventor); Young, Ken (Inventor); Hindle, Timothy (Inventor)

2016-01-01

Launch lock assemblies with reduced preload are provided. The launch lock assembly comprises first and second mount pieces, a releasable clamp device, and a pair of retracting assemblies. Each retracting assembly comprises a pair of toothed members having interacting toothed surfaces. The releasable clamp device normally maintains the first and second mount pieces in clamped engagement. When the releasable clamp device is actuated, the first and second mount pieces are released from clamped engagement and one toothed member of each retracting assembly moves in an opposite direction relative to the other one toothed member of the other retracting assembly to define an axial gap on each side of the first mount piece.

Near-surface structural examination of human tooth enamel subject to in vitro demineralization and remineralization

NASA Astrophysics Data System (ADS)

Gaines, Carmen Veronica

The early stages of chemical tooth decay are governed by dynamic processes of demineralization and remineralization of dental enamel that initiates along the surface of the tooth. Conventional diagnostic techniques lack the spatial resolution required to analyze near-surface structural changes in enamel at the submicron level. In this study, slabs of highly-polished, decay-free human enamel were subjected to 0.12M EDTA and buffered lactic acid demineralizing agents and MI Paste(TM) and calcifying (0.1 ppm F) remineralizing treatments in vitro. Grazing incidence x-ray diffraction (GIXD), a technique typically used for thin film analysis, provided depth profiles of crystallinity changes in surface enamel with a resolution better than 100 nm. In conjunction with nanoindentation, a technique gaining acceptance as a means of examining the mechanical properties of sound enamel, these results were corroborated with well-established microscopy and Raman techniques to assess the nanohardness, morphologies and chemical nature of treated enamel. Interestingly, the average crystallite size of surface enamel along its c-axis dimension increased by nearly 40% after a 60 min EDTA treatment as detected by GIXD. This result was in direct contrast to the obvious surface degradation observed by microscopic and confocal Raman imaging. A decrease in nanohardness from 4.86 +/- 0.44 GPa to 0.28 +/- 0.10 GPa was observed. Collective results suggest that mineral dissolution characteristics evident on the micron scale may not be fully translated to the nanoscale in assessing the integrity of chemically-modified tooth enamel. While an intuitive decrease in enamel crystallinity was observed with buffered lactic acid-treated samples, demineralization was too slow to adequately quantify the enamel property changes seen. MI Paste(TM) treatment of EDTA-demineralized enamel showed preferential growth along the a-axis direction. Calcifying solution treatments of both demineralized sample types appeared to have negligible effects on enamel crystallinity. Both remineralizing agents provided an increase in resiliency within the enamel surface layers. Findings from this study may prove useful in identifying more effective methods to prevent enamel demineralization and to promote and/or enhance remineralization for the treatment of tooth decay. Careful consideration of the nanoscale properties of treated surface enamel may lead to an understanding of how to truly regenerate decomposed enamel mineral from the inside out.

[The application of air abrasion in dentistry].

PubMed

Mandinić, Zoran; Vulićević, Zoran R; Beloica, Milos; Radović, Ivana; Mandić, Jelena; Carević, Momir; Tekić, Jasmina

2014-01-01

One of the main objectives of contemporary dentistry is to preserve healthy tooth structure by applying techniques of noninvasive treatment. Air abrasion is a minimally invasive nonmechanical technique of tooth preparation that uses kinetic energy to remove carious tooth structure. A powerful narrow stream of moving aluminum-oxide particles hit the tooth surface and they abrade it without heat, vibration or noise. Variables that affect speed of cutting include air pressure, particle size, powder flow, tip's size, angle and distance from the tooth. It has been proposed that air abrasion can be used to diagnose early occlusal-surface lesions and treat them with minimal tooth preparation using magnifier. Reported advantages of air abrasion include reduced noise, vibration and sensitivity. Air abrasion cavity preparations have more rounded internal contours than those prepared with straight burs. This may increase the longevity of placed restorations because it reduces the incidence of fractures and a consequence of decreased internal stresses. However, air abrasion cannot be used for all patients, i.e. in cases involving severe dust allergy, asthma, chronic obstructive lung disease, recent extraction or other oral surgery, open wounds, advanced periodontal disease, recent placement of orthodontic appliances and oral abrasions, or subgingival caries removal. Many of these conditions increase the risk of air embolism in the oral soft tissues. Dust control is a challenge, and it necessitates the use of rubber dam, high-volume evacuation, protective masks and safety eyewear for both the patient and the therapist.

Manual for automatic generation of finite element models of spiral bevel gears in mesh

NASA Technical Reports Server (NTRS)

Bibel, G. D.; Reddy, S.; Kumar, A.

1994-01-01

The goal of this research is to develop computer programs that generate finite element models suitable for doing 3D contact analysis of faced milled spiral bevel gears in mesh. A pinion tooth and a gear tooth are created and put in mesh. There are two programs: Points.f and Pat.f to perform the analysis. Points.f is based on the equation of meshing for spiral bevel gears. It uses machine tool settings to solve for an N x M mesh of points on the four surfaces, pinion concave and convex, and gear concave and convex. Points.f creates the file POINTS.OUT, an ASCI file containing N x M points for each surface. (N is the number of node points along the length of the tooth, and M is nodes along the height.) Pat.f reads POINTS.OUT and creates the file tl.out. Tl.out is a series of PATRAN input commands. In addition to the mesh density on the tooth face, additional user specified variables are the number of finite elements through the thickness, and the number of finite elements along the tooth full fillet. A full fillet is assumed to exist for both the pinion and gear.

Quantitative three-dimensional microtextural analyses of tooth wear as a tool for dietary discrimination in fishes

PubMed Central

Purnell, Mark; Seehausen, Ole; Galis, Frietson

2012-01-01

Resource polymorphisms and competition for resources are significant factors in speciation. Many examples come from fishes, and cichlids are of particular importance because of their role as model organisms at the interface of ecology, development, genetics and evolution. However, analysis of trophic resource use in fishes can be difficult and time-consuming, and for fossil fish species it is particularly problematic. Here, we present evidence from cichlids that analysis of tooth microwear based on high-resolution (sub-micrometre scale) three-dimensional data and new ISO standards for quantification of surface textures provides a powerful tool for dietary discrimination and investigation of trophic resource exploitation. Our results suggest that three-dimensional approaches to analysis offer significant advantages over two-dimensional operator-scored methods of microwear analysis, including applicability to rough tooth surfaces that lack distinct scratches and pits. Tooth microwear textures develop over a longer period of time than is represented by stomach contents, and analyses based on textures are less prone to biases introduced by opportunistic feeding. They are more sensitive to subtle dietary differences than isotopic analysis. Quantitative textural analysis of tooth microwear has a useful role to play, complementing existing approaches, in trophic analysis of fishes—both extant and extinct. PMID:22491979

Tooth wear: a cross-sectional investigation of the prevalence and risk factors in Beijing, China

PubMed Central

Sun, Kan; Wang, Wenhui; Wang, Xiaozhe; Shi, Xiangru; Si, Yan; Zheng, Shuguo

2017-01-01

Objectives: The aim of this study was to evaluate the epidemiology of tooth wear in Beijing and to establish appropriate preventive measures. Materials and Methods: This cross-sectional analysis involved a questionnaire survey conducted for 1,812 individuals aged 12–74 years in Beijing. Subjects were local residents living in the region for >6 months before the survey. Subjects were evaluated using clinical examinations with the basic erosive wear examination index and a self-administered questionnaire. Statistical analyses were performed using SPSS software. Results: The prevalence of maxillary tooth wear was 84.9% for the molars, 68.9% for the premolars, 74.1% for the canines and 97% for the incisors. In the mandible, the corresponding prevalence rates were 85.2%, 59.3%, 78.6% and 97.4%, respectively. The occlusal, incisal and cervical surfaces showed more frequent wear compared with the other surfaces. Age, acidic beverages, xerostomia and brushing habits were identified as risk factors for tooth wear (P<0.05). Conclusions: Tooth wear is common in Beijing. Specific preventive measures should be recommended for individuals reporting excessive consumption of fruits and/or acidic beverages, and those with xerostomia. In particular, incisor wear should be carefully monitored in individuals of all age groups. PMID:29607073

A Method for Thermal Analysis of Spiral Bevel Gears

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Kicher, Thomas P.

1994-01-01

A modeling method for analyzing the three-dimensional thermal behavior of spiral bevel gears has been developed. The model surfaces are generated through application of differential geometry to the manufacturing process for face-milled spiral bevel gears. Contact on the gear surface is found by combining tooth contact analysis with three-dimensional Hertzian theory. The tooth contact analysis provides the principle curvatures and orientations of the two surfaces. This information is then used directly in the Hertzian analysis to find the contact size and maximum pressure. Heat generation during meshing is determined as a function of the applied load, sliding velocity, and coefficient of friction. Each of these factors change as the point of contact changes during meshing. A nonlinear finite element program was used to conduct the heat transfer analysis. This program permitted the time- and position-varying boundary conditions, found in operation, to be applied to a one-tooth model. An example model and analytical results are presented.

Can dead man tooth do tell tales? Tooth prints in forensic identification.

PubMed

Christopher, Vineetha; Murthy, Sarvani; Ashwinirani, S R; Prasad, Kulkarni; Girish, Suragimath; Vinit, Shashikanth Patil

2017-01-01

We know that teeth trouble us a lot when we are alive, but they last longer for thousands of years even after we are dead. Teeth being the strongest and resistant structure are the most significant tool in forensic investigations. Patterns of enamel rod end on the tooth surface are known as tooth prints. This study is aimed to know whether these tooth prints can become a forensic tool in personal identification such as finger prints. A study has been targeted toward the same. In the present in-vivo study, acetate peel technique has been used to obtain the replica of enamel rod end patterns. Tooth prints of upper first premolars were recorded from 80 individuals after acid etching using cellulose acetate strips. Then, digital images of the tooth prints obtained at two different intervals were subjected to biometric conversion using Verifinger standard software development kit version 6.5 software followed by the use of Automated Fingerprint Identification System (AFIS) software for comparison of the tooth prints. Similarly, each individual's finger prints were also recorded and were subjected to the same software. Further, recordings of AFIS scores obtained from images were statistically analyzed using Cronbach's test. We observed that comparing two tooth prints taken from an individual at two intervals exhibited similarity in many cases, with wavy pattern tooth print being the predominant type. However, the same prints showed dissimilarity when compared with other individuals. We also found that most of the individuals with whorl pattern finger print showed wavy pattern tooth print and few loop type fingerprints showed linear pattern of tooth prints. Further more experiments on both tooth prints and finger prints are required in establishing an individual's identity.

Can dead man tooth do tell tales? Tooth prints in forensic identification

PubMed Central

Christopher, Vineetha; Murthy, Sarvani; Ashwinirani, S. R.; Prasad, Kulkarni; Girish, Suragimath; Vinit, Shashikanth Patil

2017-01-01

Background: We know that teeth trouble us a lot when we are alive, but they last longer for thousands of years even after we are dead. Teeth being the strongest and resistant structure are the most significant tool in forensic investigations. Patterns of enamel rod end on the tooth surface are known as tooth prints. Aim: This study is aimed to know whether these tooth prints can become a forensic tool in personal identification such as finger prints. A study has been targeted toward the same. Settings and Design: In the present in-vivo study, acetate peel technique has been used to obtain the replica of enamel rod end patterns. Materials and Methods: Tooth prints of upper first premolars were recorded from 80 individuals after acid etching using cellulose acetate strips. Then, digital images of the tooth prints obtained at two different intervals were subjected to biometric conversion using Verifinger standard software development kit version 6.5 software followed by the use of Automated Fingerprint Identification System (AFIS) software for comparison of the tooth prints. Similarly, each individual's finger prints were also recorded and were subjected to the same software. Statistical Analysis: Further, recordings of AFIS scores obtained from images were statistically analyzed using Cronbach's test. Results: We observed that comparing two tooth prints taken from an individual at two intervals exhibited similarity in many cases, with wavy pattern tooth print being the predominant type. However, the same prints showed dissimilarity when compared with other individuals. We also found that most of the individuals with whorl pattern finger print showed wavy pattern tooth print and few loop type fingerprints showed linear pattern of tooth prints. Conclusions: Further more experiments on both tooth prints and finger prints are required in establishing an individual's identity. PMID:28584483

[Effect of gap size between tooth and restorative materials on microbiolism based caries in vitro].

PubMed

Lu, Wen-bin; Li, Yun

2012-05-01

To evaluate the effect of gap size between tooth and restorative materials on microbiolism based caries in vitro. Tooth blocks made of human molars without caries and the same size composite resin blocks were selected and prepared. Tooth-resin matrix was mounted on resin base with a gap size of 0, 25, 50, 100, 190, 250 µm and a control group was dealed with adhesive system. Six experimental groups and one control group were included, with 8 samples in one group and a total of 56 samples. The samples were cultured by a 14-day sequential batch culture technique. The development of outer surface lesion and wall lesion was assessed with confocal laser scanning microscope (CLSM) by measuring the maximum lesion depth, fluorescence areas and average fluorescence value. The data were collected and statistically analyzed. The deposits of the tooth-restoration interface and the development of the carious lesion were observed by scanning electron microscope (SEM). Most groups showed outer surface lesion and wall surface lesions observed by CLSM and SEM except 2 samples in control group. There was no significant difference on the outer surface lesion (P > 0.05). The maximum lesion depth [(1145.37 ± 198.98), (1190.12 ± 290.80) µm respectively], the maximum lesion length, fluorescence areas and average fluorescence value of 190 and 250 µm groups' wall lesions were significantly higher than the 0, 25, 50 and 100 µm groups [the maximum lesion depth was (205.25 ± 122.61), (303.87 ± 118.80), (437.75 ± 154.88), (602.87 ± 269.13) µm respectively], P < 0.01. With the increase of the gap size, the demineralization developed more seriously. While the maximum lesion depth, the maximum lesion length and fluorescence areas of 0, 25, 50 µm groups' wall lesions were of no significant difference. There was close relationship between gap size and wall lesion when the gap was above 100 µm at tooth-composite resin interface. The existence of gap was the main influencing factor on the development of microbiolism based caries lesion.

Bcl-2 expression is essential for development and normal physiological properties of tooth hard tissue and saliva production.

PubMed

Saghiri, Mohammad Ali; Asatourian, Armen; Gurel, Zafer; Sorenson, Christine M; Sheibani, Nader

2017-09-15

Apoptosis plays a fundamental role in appropriate tissue development and function. Although expression of Bcl-2 has been reported during tooth and submandibular gland (SMG) development, the physiological role Bcl-2 plays during these processes has not been addressed. This study was performed to evaluate the impact of Bcl-2 expression on the formation and properties of tooth hard tissue, and saliva production. Twenty-four mice (12 males and 12 females) were divided into three groups of eight (n=8): group A (Bcl-2 +/+), group B (Bcl-2 +/-), and group C (Bcl-2 -/-) and subjected to micro-CT analyses. The mineral content of first molars was analyzed by X-Ray diffraction (XRD) and scanning electron microscopy (SEM) color dot map. The surface microhardness was determined by Vickers test on labial surfaces of incisors. Saliva was collected from different groups of mice after subcutaneous injection of pilocarpine. Samples from Bcl-2 -/- mice showed significantly smaller micro-CT values, lower and poor crystallinity of hydroxyapatite (HA), and lowest surface micro hardness. SMG from Bcl-2 -/- mice showed remarkable reduction in size, consistent with reduced saliva accumulation. The absence of Bcl-2 expression in SMG did not affect the expression of other Bcl-2 family members. Thus, Bcl-2 expression influence on the formation and properties of tooth hard tissue, and saliva accumulation. Bcl-2 expression has a significant impact on the mineralogical content of enamel crystals of tooth structure. Lack of Bcl-2 expression led to impaired production of enamel ACP crystals. Copyright © 2017 Elsevier Inc. All rights reserved.

Hearing Loss in Stranded Odontocete Dolphins and Whales

PubMed Central

Mann, David; Hill-Cook, Mandy; Manire, Charles; Greenhow, Danielle; Montie, Eric; Powell, Jessica; Wells, Randall; Bauer, Gordon; Cunningham-Smith, Petra; Lingenfelser, Robert; DiGiovanni, Robert; Stone, Abigale; Brodsky, Micah; Stevens, Robert; Kieffer, George; Hoetjes, Paul

2010-01-01

The causes of dolphin and whale stranding can often be difficult to determine. Because toothed whales rely on echolocation for orientation and feeding, hearing deficits could lead to stranding. We report on the results of auditory evoked potential measurements from eight species of odontocete cetaceans that were found stranded or severely entangled in fishing gear during the period 2004 through 2009. Approximately 57% of the bottlenose dolphins and 36% of the rough-toothed dolphins had significant hearing deficits with a reduction in sensitivity equivalent to severe (70–90 dB) or profound (>90 dB) hearing loss in humans. The only stranded short-finned pilot whale examined had profound hearing loss. No impairments were detected in seven Risso's dolphins from three different stranding events, two pygmy killer whales, one Atlantic spotted dolphin, one spinner dolphin, or a juvenile Gervais' beaked whale. Hearing impairment could play a significant role in some cetacean stranding events, and the hearing of all cetaceans in rehabilitation should be tested. PMID:21072206

Hearing loss in stranded odontocete dolphins and whales.

PubMed

Mann, David; Hill-Cook, Mandy; Manire, Charles; Greenhow, Danielle; Montie, Eric; Powell, Jessica; Wells, Randall; Bauer, Gordon; Cunningham-Smith, Petra; Lingenfelser, Robert; DiGiovanni, Robert; Stone, Abigale; Brodsky, Micah; Stevens, Robert; Kieffer, George; Hoetjes, Paul

2010-11-03

The causes of dolphin and whale stranding can often be difficult to determine. Because toothed whales rely on echolocation for orientation and feeding, hearing deficits could lead to stranding. We report on the results of auditory evoked potential measurements from eight species of odontocete cetaceans that were found stranded or severely entangled in fishing gear during the period 2004 through 2009. Approximately 57% of the bottlenose dolphins and 36% of the rough-toothed dolphins had significant hearing deficits with a reduction in sensitivity equivalent to severe (70-90 dB) or profound (>90 dB) hearing loss in humans. The only stranded short-finned pilot whale examined had profound hearing loss. No impairments were detected in seven Risso's dolphins from three different stranding events, two pygmy killer whales, one Atlantic spotted dolphin, one spinner dolphin, or a juvenile Gervais' beaked whale. Hearing impairment could play a significant role in some cetacean stranding events, and the hearing of all cetaceans in rehabilitation should be tested.

Rinsing with antacid suspension reduces hydrochloric acid-induced erosion.

PubMed

Alves, Maria do Socorro Coelho; Mantilla, Taís Fonseca; Bridi, Enrico Coser; Basting, Roberta Tarkany; França, Fabiana Mantovani Gomes; Amaral, Flávia Lucisano Botelho; Turssi, Cecilia Pedroso

2016-01-01

Mouthrinsing with antacids, following erosive episodes, have been suggested as a preventative strategy to minimize tooth surface loss due to their neutralizing effect. The purpose of this in situ study was to evaluate the effect of an antacid suspension containing sodium alginate, sodium bicarbonate and calcium carbonate in controlling simulated erosion of enamel of intrinsic origin. The experimental units were 48 slabs (3×3×2mm) of bovine enamel, randomly divided among 12 volunteers who wore palatal appliances with two enamel slabs. One of them was exposed extra-orally twice a day to 25mL of a hydrochloric acid (HCl) solution (0.01M, pH 2) for 2min. There were two independent phases, lasting 5 days each. In the first phase, according to a random scheme, half of the participants rinsed with 10mL of antacid suspension (Gaviscon(®), Reckitt Benckiser Healthcare Ltd.), while the remainder was rinsed with deionized water, for 1min. For the second phase, new slabs were inserted and participants switched to the treatment not received in the first stage. Therefore, the groups were as follows: (a) erosive challenge with HCl+antacid suspension; (b) erosive challenge with HCl+deionized water (DIW); (c) no erosive challenge+antacid suspension; (d) no erosive challenge+DIW. Specimens were assessed in terms of surface loss using optical profilometry and Knoop microhardness. The data were analyzed using repeated measures two-way analysis of variance and Tukey's tests. Compared to DIW rinses, surface loss of enamel was significantly lower when using an antacid rinse following erosive challenges (p=0.015). The Knoop microhardness of the enamel was significantly higher when the antacid rinse was used (p=0.026). The antacid suspension containing sodium alginate, sodium bicarbonate and calcium carbonate, rinsed after erosive challenges of intrinsic origin, reduced enamel surface loss. Copyright © 2015 Elsevier Ltd. All rights reserved.

In vitro study on tooth enamel lesions related to whitening dentifrice.

PubMed

de Araújo, Danilo Barral; Silva, Luciana Rodrigues; Campos, Elisângela de Jesus; Correia de Araújo, Roberto Paulo

2011-01-01

The tooth whitening substances for extrinsic use that are available in Brazil contain hydrogen peroxide or carbamide peroxide. Several studies have attributed the appearance of lesions in the enamel morphology, including hypersensitivity, to these substances. Such lesions justify fluoride therapy and application of infrared lasers, among other procedures. However, there is no consensus among researchers regarding the relevance of the severity of lesions detected on the tooth surface. The present study was carried out with an aim of evaluating in vitro the effects of the hydrogen peroxide, carbamide peroxide and sodium bicarbonate contained in dentifrice formulations, on human tooth enamel. After darkening process in laboratory, human premolars were brushed using dentifrice containing the two whitening substances (Rembrandt - carbamide peroxide and Mentadent - hydrogen peroxide) and the abrasive product (Colgate - sodium bicarbonate). The degree of specimen staining before and after this procedure was determined using spectrophotometry. Scanning electron microscopy (SEM) was used to obtain images, which were analyzed to show the nature of the lesions that appeared on the enamel surface. The effectiveness of the whitening caused by hydrogen peroxide and carbamide peroxide and the abrasion caused by bicarbonate were confirmed, given that the treated test pieces returned to their original coloration. Based on SEM, evaluation of the enamel surfaces subjected to the test products showed that different types of morphologic lesions of varying severity appeared. Whitening dentifrice containing hydrogen peroxide and carbamide peroxide produced lesions on the enamel surface such that the greatest sequelae were associated with exposure to hydrogen peroxide.

In vivo tooth-color measurement with a new 3D intraoral scanning system in comparison to conventional digital and visual color determination methods.

PubMed

Mehl, Albert; Bosch, Gabriel; Fischer, Carolin; Ender, Andreas

Three-dimensional (3D) intraoral scanning systems allow for the simultaneous acquisition of 3D information about tooth surfaces and a photorealistic view of the patient's tooth colors. The goal of this study was the in vivo comparison of a new 3D scanner with a color acquisition mode and conventional visual and digital color measurements. The colors of 40 teeth of 20 patients were evaluated in seven ways: 1) By dentists using the Vita 3D-Master; 2) By dental technicians using the Vita 3D-Master; 3) With the 3Shape Trios device; 4) With the Vita Easyshade device; 5) With the Vita Easyshade Advance device; 6) With the SpectroShade device; and 7) With the SpectroShade Micro device. Digital measurements of Groups 3 to 7 were repeated three times for each tooth. For all groups, both the CIE Lab values and the Vita 3D-Master values were recorded. The repeatability and relative accuracy of the Vita 3D-Master values were analyzed statistically using Pearson's chi-squared test (α < 0.05). ΔE values were calculated from the CIE Lab values, which served as a basis for performing multidimensional scaling (MDS) and evaluating differences between the groups using the one-way ANOVA with post hoc Tamhane's test (α < 0.05). The results of the ΔE values showed that clinically relevant differences between the evaluation by dentists, dental technicians, and the intraoral scanning device (3Shape) are negligible. The intraoral 3D scanning device (Group 3) and the digital systems (Groups 4 to 7) did not differ significantly in the repeatability of color shade management. The SpectroShade Micro (Group 7) had significantly better relative accuracy than the other devices. The results demonstrate that intraoral scanning systems can be used to measure both tooth color and tooth surface in 3D. Intraoral optical scanning devices allow for the acquisition of accurate 3D surface data. Tooth color can be evaluated simultaneously and can be used to determine the color of restorations without requiring additional conventional color-measurement methods.

Effect of restoration technique on stress distribution in roots with flared canals: an FEA study.

PubMed

Belli, Sema; Eraslan, Öznur; Eraslan, Oğuz; Eskitaşcıoğlu, Gürcan

2014-04-01

The aim of this finite element analysis (FEA) study was to test the effect of different restorative techniques on stress distribution in roots with flared canals. Five three-dimensional (3D) FEA models that simulated a maxillary incisor with excessive structure loss and flared root canals were created and restored with the following techniques/materials: 1) a prefabricated post: 2) one main and two accessory posts; 3) i-TFC post-core (Sun Medical); 4) the thickness of the root was increased by using composite resin and the root was then restored using a prefabricated post; 5) an anatomic post was created by using composite resin and a prefabricated glass-fiber post. Composite cores and ceramic crowns were created. A 300-N static load was applied at the center of the palatal surface of the tooth to calculate stress distributions. SolidWorks/Cosmosworks structural analysis programs were used for FEA analysis. The analysis of the von Mises and tensile stress values revealed that prefabricated post, accessory post, and i-TFC post systems showed similar stress distributions. They all showed high stress areas at the buccal side of the root (3.67 MPa) and in the cervical region of the root (> 3.67 MPa) as well as low stress accumulation within the post space (0 to 1 MPa). The anatomic post kept the stress within its body and directed less stress towards the remaining tooth structure. The creation of an anatomic post may save the remaining tooth structure in roots with flared canals by reducing the stress levels.

Consensus report of the European Federation of Conservative Dentistry: erosive tooth wear--diagnosis and management.

PubMed

Carvalho, T S; Colon, P; Ganss, C; Huysmans, M C; Lussi, A; Schlueter, N; Schmalz, G; Shellis, R P; Tveit, A B; Wiegand, A

2015-09-01

Due to an increased focus on erosive tooth wear (ETW), the European Federation of Conservative Dentistry (EFCD) considered ETW as a relevant topic for generating this consensus report. This report is based on a compilation of the scientific literature, an expert conference, and the approval by the General Assembly of EFCD. ETW is a chemical-mechanical process resulting in a cumulative loss of hard dental tissue not caused by bacteria, and it is characterized by loss of the natural surface morphology and contour of the teeth. A suitable index for classification of ETW is the basic erosive wear examination (BEWE). Regarding the etiology, patient-related factors include the pre-disposition to erosion, reflux, vomiting, drinking and eating habits, as well as medications and dietary supplements. Nutritional factors relate to the composition of foods and beverages, e.g., with low pH and high buffer capacity (major risk factors), and calcium concentration (major protective factor). Occupational factors are exposition of workers to acidic liquids or vapors. Preventive management of ETW aims at reducing or stopping the progression of the lesions. Restorative management aims at reducing symptoms of pain and dentine hypersensitivity, or to restore esthetic and function, but it should only be used in conjunction with preventive strategies. Effective management of ETW includes screening for early signs of ETW and evaluating all etiological factors. ETW is a clinical condition, which calls for the increased attention of the dental community and is a challenge for the cooperation with other medical specialities.

Percentage and severity of periodontal diseases in Turkish adults aged 35+ years, 2009-10.

PubMed

Ilhan, Duygu; Oktay, Inci; Nur, Burcu; Fisekcioglu, Erdogan; Lim, Sungwoo; Lepkowski, James M; Ismail, Amid I

2017-09-01

This article presents data on the burden of periodontal diseases in Turkish adults aged 35 years or older. Within each region of Turkey, a rural and an urban area or city were selected in 2009-10 using a probability proportional to size method. In the selected towns, local officials who were familiar with their communities assisted in recruiting subjects. Loss of Attachment (LOA) was measured at six sites around each tooth present in the mouth, excluding third molars. Additionally, the Community Periodontal Index was used to assess the severity of periodontal diseases around 12 index teeth. Self-reported data on key risk factors were also collected. Weights were computed using a raking ratio adjustment procedure and used in all analyses. Almost all examined adults had some loss of periodontal attachment. The proportion of those with more than 3 mm LOA ranged from 43 percent in 35-44 year olds to 91 percent in those aged 65+ years. Among females, older age, low education status, smoking 11-40+ cigarettes a day, being employed, and presence of high number of missing tooth surfaces were associated with LOA > 3 mm. Among males LOA >3 mm was associated with older age, use of alcohol, and unemployment. The CPI data did not yield the same associations with periodontal diseases and risk factors. Periodontal diseases in Turkish adults are highly prevalent. A tailored common risk factor health promotion program is recommended to reduce the burden of periodontal infection in Turkey. © 2017 American Association of Public Health Dentistry.

75 FR 3395 - Taking and Importing Marine Mammals; U.S. Naval Surface Warfare Center Panama City Division...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-21

... al., 2003; 2004)). A detailed review of marine mammal reactions to ships and boats is available in... the following assessment regarding cetacean reactions to vessel traffic: Toothed whales: ``In summary, toothed whales sometimes show no avoidance reaction to vessels, or even approach them. However, avoidance...

Coupling image processing and stress analysis for damage identification in a human premolar tooth.

PubMed

Andreaus, U; Colloca, M; Iacoviello, D

2011-08-01

Non-carious cervical lesions are characterized by the loss of dental hard tissue at the cement-enamel junction (CEJ). Exceeding stresses are therefore generated in the cervical region of the tooth that cause disruption of the bonds between the hydroxyapatite crystals, leading to crack formation and eventual loss of enamel and the underlying dentine. Damage identification was performed by image analysis techniques and allowed to quantitatively assess changes in teeth. A computerized two-step procedure was generated and applied to the first left maxillary human premolar. In the first step, dental images were digitally processed by a segmentation method in order to identify the damage. The considered morphological properties were the enamel thickness and total area, the number of fragments in which the enamel is chipped. The information retrieved by the data processing of the section images allowed to orient the stress investigation toward selected portions of the tooth. In the second step, a three-dimensional finite element model based on CT images of both the tooth and the periodontal ligament was employed to compare the changes occurring in the stress distributions in normal occlusion and malocclusion. The stress states were analyzed exclusively in the critical zones designated in the first step. The risk of failure at the CEJ and of crack initiation at the dentin-enamel junction through the quantification of first and third principal stresses, von Mises stress, and normal and tangential stresses, were also estimated. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

The influence of type 1 and type 2 diabetes on periodontal disease progression: prospective results from the Study of Health in Pomerania (SHIP).

PubMed

Demmer, Ryan T; Holtfreter, Birte; Desvarieux, Moïse; Jacobs, David R; Kerner, Wolfgang; Nauck, Matthias; Völzke, Henry; Kocher, Thomas

2012-10-01

To explore associations between diabetes etiology (type 1 diabetes mellitus [T1DM] vs. T2DM) and glycemic control in the prediction of 5-year periodontal status change. The Study of Health in Pomerania (SHIP) is a population-based stratified sample of German men and women. Healthy participants and those determined to have T2DM arose from the SHIP cohort, and T1DM participants were recruited from diabetes clinics in the catchment area that gave rise to SHIP. Dentate participants (n = 2,626; 53% women; 20-81 years of age) were included. Diabetes was determined via physician diagnosis and/or HbA(1c) ≥6.5% (uncontrolled diabetes >7.0%). Examiners blinded to diabetes status performed random half-mouth periodontal examinations, assessing probing depth (PD) and attachment loss (AL) (four sites/tooth) at baseline and follow-up. Participants were categorized into six groups as follows: 1) diabetes free (n = 2,280), 2) incident T2DM (n = 79), 3) controlled T2DM (n = 80), 4) uncontrolled T2DM (n = 72), 5) controlled T1DM (n = 43), and 6) uncontrolled T1DM (n = 72). In multivariable regressions, mean PD change (ΔMPD), mean AL change (ΔMAL), or incident tooth-loss values were regressed across the aforementioned diabetes categories. Mean (SD) ΔMPD and ΔMAL values among all participants were -0.08 ± 0.5 mm and 0.08 ± 1.03 mm, respectively, and 34% lost one or more teeth. Relative to diabetes-free participants, those with uncontrolled T2DM experienced greater ΔMPD ± SE (P < 0.05), whereas participants with either uncontrolled T1DM or uncontrolled T2DM realized greater ΔMAL (P < 0.05). Uncontrolled T1DM and T2DM were both associated with an increased risk of future tooth loss (P < 0.05). Diabetes control, but not etiology, was associated with future tooth loss and accelerated AL progression.

A case report of a TPS dental implant rigidly connected to a natural tooth: 19-year follow-up.

PubMed

Quaranta, Alessandro; Poli, Ottavia; Vozza, Iole

2013-01-01

A partial edentulous area was restored with a tooth to implant fixed partial denture and a rigid connection between the two elements. Maintenance recalls were performed over a 19-year period of observation on a yearly basis. THE FOLLOWING PARAMETERS WERE COLLECTED DURING EACH EXAMINATION OVER THE ENTIRE PERIOD OF OBSERVATION: PD around the implant and natural tooth abutment, gingival index, modified gingival index, plaque index, modified plaque index, occlusal assessment, marginal bone loss. Radiographic assessment of peri-implant bone remodeling was performed in a retrospective way. The following reference points were assessed on each image: fixture-abutment junction, threads, first contact of the crestal bone with the implant on both mesial and distal side. This made possible, with the known values for implant diameter and length, to make linear measurements of remaining peri-implant bone measured from the mesial and distal marginal bone levels and the fixture-abutment junction. The amount of bone change over the baseline to a 19 years follow-up observation time was calculated for both the implant and the natural tooth. Clinical parameters showed healthy values over the entire period of observation with slight isolated positive bleeding on probing. Bone remodeling values were constant over the entire period with slight higher values around the tooth. Peri-apical radiographs did not show any intrusion of the tooth. The present case report showed the complete functionality and stability of a tooth to implant rigidly connected FPD over a period of 19 years.

Dental caries, tooth wear and diet in an adult medieval (12th-14th century) population from mediterranean France.

PubMed

Esclassan, R; Grimoud, A M; Ruas, M P; Donat, R; Sevin, A; Astie, F; Lucas, S; Crubezy, E

2009-03-01

The aims of the present work were to determine the frequency and distribution of caries and tooth wear on paired maxillae of a mediaeval sample from southwest France in which the sex of the remains had been established, and to make a relation with the diet of this population. The sample analysed consisted of the dental remains of 58 adult individuals (29 men and 29 women) excavated from the mediaeval cemetery of the archaeological site of Vilarnau d'Amont (southwest France). A total of 1395 teeth were examined. The frequency of ante-mortem tooth loss for the sample was 8.7% and the frequency of caries was 17.5%. The frequencies of carious lesions in adult men and women's dentition were 21.9% and 14.0%. The most frequent were occlusal (49.7% and 34.3%) and approximal caries (26.5% and 37.4%). Concerning tooth wear, all 58 individuals were affected by attrition (100%) and more than 90% of the teeth were concerned. Most of them showed the presence of dentin clusters. There was no significant difference between men and women for caries and tooth wear. These findings are similar to those of other studies on European populations of the same socio-economic status and confirm the predominance of tooth wear over carious lesions during this period. Both caries and tooth wear may be related to the regional diet of this rural population.

Genome-Wide Association Study of Erosive Tooth Wear in a Finnish Cohort.

PubMed

Alaraudanjoki, Viivi Karoliina; Koivisto, Salla; Pesonen, Paula; Männikkö, Minna; Leinonen, Jukka; Tjäderhane, Leo; Laitala, Marja-Liisa; Lussi, Adrian; Anttonen, Vuokko Anna-Marketta

2018-06-13

Erosive tooth wear is defined as irreversible loss of dental tissues due to intrinsic or extrinsic acids, exacerbated by mechanical forces. Recent studies have suggested a higher prevalence of erosive tooth wear in males, as well as a genetic contribution to susceptibility to erosive tooth wear. Our aim was to examine erosive tooth wear by performing a genome-wide association study (GWAS) in a sample of the Northern Finland Birth Cohort 1966 (n = 1,962). Erosive tooth wear was assessed clinically using the basic erosive wear examination. A GWAS was performed for the whole sample as well as separately for males and females. We identified one genome-wide significant signal (rs11681214) in the GWAS of the whole sample near the genes PXDN and MYT1L. When the sample was stratified by sex, the strongest genome-wide significant signals were observed in or near the genes FGFR1, C8orf86, CDH4, SCD5, F2R, and ING1. Additionally, multiple suggestive association signals were detected in all GWASs performed. Many of the signals were in or near the genes putatively related to oral environment or tooth development, and some were near the regions considered to be associated with dental caries, such as 2p24, 4q21, and 13q33. Replications of these associations in other samples, as well as experimental studies to determine the biological functions of associated genetic variants, are needed. © 2018 S. Karger AG, Basel.

Miocene Surface Temperature Estimates of the Southern Altiplano and Their Implications for Surface Uplift

NASA Astrophysics Data System (ADS)

Smith, J. J.; Garzione, C.; Higgins, P.; MacFadden, B.; Auerbach, D.; Croft, D.

2008-12-01

Surface temperature estimates derived from stable isotopes can be used to infer tectonic history and subsequent climate change of the Bolivian Altiplano. This study compares surface temperatures calculated from two fossil localities (Cerdas and Quehua) that span middle to late Miocene age in the southern Altiplano. Temperatures were calculated using the approach of Zanazzi et al. (2007) by comparing the stable isotopes of fossil tooth enamel and concurrent fossilized bones. The δ18O of the surface water is derived from fossil tooth enamel that mineralized at a known mammal body temperature. Surface water compositions are then used to calculate the temperature at which fossil bones were diagenetically altered, using the assumption that most alteration of fossil bones occurs within 20 to 50 thousand years of deposition. These surface temperature estimates can be used as a proxy for the amount of surface uplift based on modern temperature lapse rates. The vertical surface temperature gradient observed in the present-day Andes is about 4.66°C/km. Changes in surface elevations may explain large temperature changes reflected throughout the middle to late Miocene. Cerdas and Quehua, at modern elevations of ~3800m, have fossil records that include teeth and diagenetically altered bones that were deposited before and during a period of inferred rapid surface uplift of the northern Altiplano of 2.5 ± 1 km between ~10 to 6 Ma. Both sites have been dated by magnetostratigraphy and by 40Ar/39Ar dating of tuffs: Cerdas dates from 16.358 ± 0.071 to 15.105 ± 0.073 Ma, and Quehua ranges from 12.611 ± 0.034 to 6.844 ± 0.386 Ma. The close proximity and current elevation of Cerdas (21.9°S, 3800m) and Quehua (20.0°S, 3800m) allows for the assumption that their elevations were closely correlated through time. Thus the temperatures and elevation estimates derived from each location are assumed to reflect the larger extent of the southern Altiplano. If analysis of fossil enamel and bone from these locations shows a significant temperature decrease from middle to late Miocene, this would support the hypothesis of rapid regional surface uplift of the Altiplano during the late Miocene due to loss of the dense lower crust and/or lithospheric mantle.

Restorative Rehabilitation of a Patient with Dental Erosion

PubMed Central

AlShahrani, Mohammed Thamer; Alqarni, Mohammed

2017-01-01

Dental erosion is the chemical dissolution of the tooth structure. Factors like eating disorders and gastrointestinal diseases are recognized as intrinsic factors for dental erosion. Advanced stages of dental erosion extensively damage the tooth morphology, consequently affecting both esthetics and functions. Reports indicate the growing prevalence of erosion, and hence knowledge of restorative rehabilitation of tooth erosion is an integral part of the contemporary dental practice. This clinical report describes an adult patient with gastroesophageal reflux induced dental erosion involving the palatal surface of the maxillary anterior teeth. The extensive involvement of the palatal surfaces compromised the esthetics, incisal guidance, and functional occlusal efficiency. Indirect all-ceramic restorations were utilized to restore the esthetics and occlusal reconstruction. In conclusion, patients affected by severe dental erosion require prosthetic rehabilitation besides the management of the associated medical condition. PMID:28828189

Restorative Rehabilitation of a Patient with Dental Erosion.

PubMed

AlShahrani, Mohammed Thamer; Haralur, Satheesh B; Alqarni, Mohammed

2017-01-01

Dental erosion is the chemical dissolution of the tooth structure. Factors like eating disorders and gastrointestinal diseases are recognized as intrinsic factors for dental erosion. Advanced stages of dental erosion extensively damage the tooth morphology, consequently affecting both esthetics and functions. Reports indicate the growing prevalence of erosion, and hence knowledge of restorative rehabilitation of tooth erosion is an integral part of the contemporary dental practice. This clinical report describes an adult patient with gastroesophageal reflux induced dental erosion involving the palatal surface of the maxillary anterior teeth. The extensive involvement of the palatal surfaces compromised the esthetics, incisal guidance, and functional occlusal efficiency. Indirect all-ceramic restorations were utilized to restore the esthetics and occlusal reconstruction. In conclusion, patients affected by severe dental erosion require prosthetic rehabilitation besides the management of the associated medical condition.

[Construction of platform on the three-dimensional finite element model of the dentulous mandibular body of a normal person].

PubMed

Gong, Lu-Lu; Zhu, Jing; Ding, Zu-Quan; Li, Guo-Qiang; Wang, Li-Ming; Yan, Bo-Yong

2008-04-01

To develop a method to construct a three-dimensional finite element model of the dentulous mandibular body of a normal person. A series of pictures with the interval of 0.1 mm were taken by CT scanning. After extracting the coordinates of key points of some pictures by the procedure, we used a C program to process the useful data, and constructed a platform of the three-dimensional finite element model of the dentulous mandibular body with the Ansys software for finite element analysis. The experimental results showed that the platform of the three-dimensional finite element model of the dentulous mandibular body was more accurate and applicable. The exact three-dimensional shape of model was well constructed, and each part of this model, such as one single tooth, can be deleted, which can be used to emulate various tooth-loss clinical cases. The three-dimensional finite element model is constructed with life-like shapes of dental cusps. Each part of this model can be easily removed. In conclusion, this experiment provides a good platform of biomechanical analysis on various tooth-loss clinical cases.

Attrition and erosion: restorative planning and performance.

PubMed

Burrow, Michael F

2012-04-01

The number of patients presenting with severe attrition and associated erosion is increasing in frequency. Treatment of this patient group is very challenging as it is simply not just a case of replacing lost tooth tissue, but also trying to identify and then eliminate the aetiological factors responsible for the loss of tooth structure. In most cases restorative treatment involves extensive rehabilitation of the dentition to restore the aesthetics and function and also to prevent further tooth loss. Such treatment often involves a multidisciplinary approach to eliminate and/or reduce causative factors prior to definitive restoration of teeth. Treatment needs to focus on quick intervention when the problem has been identified and diagnosed. Restorative treatment involves careful if not complex planning culminating in the establishment of a well defined and ongoing maintenance plan. Long-term success of treatment is centred on the maintenance phase. Current restorative options include the use of extensive resin composite build-ups. This is often the best initial starting point as it allows for adjustments, as well as being a reversible and more conservative procedure. The use of indirect restorations is likely to provide a longer lasting outcome after initial stabilization, whether it is metal- or ceramic-based or a combination.

Surface modifications of dental implants.

PubMed

Stanford, C M

2008-06-01

Dental implant surface technologies have been evolving rapidly to enhance a more rapid bone formation on their surface and hold a potential to increase the predictability of expedited implant therapy. While implant outcomes have become highly predictable, there are sites and conditions that result in elevated implant loss. This paper reviews the impact of macro-retentive features which includes approaches to surface oxide modification, thread design, press-fit and sintered-bead technologies to increase predictability of outcomes. Implant designs that lead to controlled lateral compression of the bone can improve primary stability as long as the stress does not exceed the localized yield strength of the cortical bone. Some implant designs have reduced crestal bone loss by use of multiple cutting threads that are closely spaced, smoothed on the tip but designed to create a hoop-stress stability of the implant as it is completely seated in the osteotomy. Following the placement of the implant, there is a predictable sequence of bone turnover and replacement at the interface that allows the newly formed bone to adapt to microscopic roughness on the implant surface, and on some surfaces, a nanotopography (<10(-9) m scale) that has been shown to preferably influence the formation of bone. Newly emerging studies show that bone cells are exquisitely sensitive to these topographical features and will upregulate the expression of bone related genes for new bone formation when grown on these surfaces. We live in an exciting time of rapid changes in the modalities we can offer patients for tooth replacement therapy. Given this, it is our responsibility to be critical when claims are made, incorporate into our practice what is proven and worthwhile, and to continue to support and provide the best patient care possible.

Regenerative Endodontic Treatment with Orthodontic Treatment in a Tooth with Dens Evaginatus: A Case Report with a 4-year Follow-up.

PubMed

Natera, Marianella; Mukherjee, Padma M

2018-06-01

Dens evaginatus is a developmental tooth anomaly in which an extra cusp or tubercle protrudes on the occlusal surface of the tooth along with some pulpal tissue. Because of the fragile nature of the protrusion, these teeth are often at risk of pulpal exposure. When this occurs in an immature tooth, regenerative endodontic treatment may be a good treatment approach to promote root formation. There is limited literature that documents the occurrence of orthodontic treatment in teeth that have undergone regenerative endodontic therapy using triple antibiotic paste. Here we present a case of an immature premolar tooth with dens evaginatus that was diagnosed with pulp necrosis and chronic apical abscess. The tooth was treated with regenerative endodontic treatment; after which, the patient received orthodontic treatment with fixed appliances for 2 years. The tooth responded favorably to the regenerative endodontic treatment and orthodontic tooth movement. Clinically and radiographically, all the follow-up examinations revealed an asymptomatic tooth with evidence of periapical healing with stunted root development. The tooth remained asymptomatic even after 4 years. The regenerative endodontic procedure (REP) was successful in treating an immature permanent premolar with pulp necrosis and apical periodontitis with dens evaginatus. In this case, the tooth treated with an REP responded to orthodontic treatment similar to the nonendodontically treated teeth. Further studies are recommended to clarify the precise effects of orthodontic treatment on teeth treated with an REP. Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Oral Health and Bone Disease

MedlinePlus

... Oral Health and Bone Disease Oral Health and Bone Disease Osteoporosis and tooth loss are health concerns ... for Healthy Bones Resources For Your Information Skeletal Bone Density and Dental Concerns The portion of the ...

Canine Gouging: A Taboo Resurfacing in Migrant Urban Population.

PubMed

Noman, Anila Virani; Wong, Ferranti; Pawar, Ravikiran Ramakrishna

2015-01-01

Cosmopolitan cities have become a pool of migrants from different parts of the world, who carry their cultural beliefs and superstitions with them around the globe. Canine gouging is a kind of infant oral mutilation (IOM) which is widely practiced among rural population of Africa where the primary tooth bud of the deciduous canine is enucleated. The belief is that the life threatening illnesses in children like vomiting, diarrhoea, and fevers are caused by worms which infest on tooth buds. This case report is of a 15-year-old Somalian born boy, who presented at the dental institute with intermittent pain in his lower right permanent canine which was associated with a discharging intra oral buccal sinus. The tooth was endodontically treated and then restored with composite. General dental practitioners need to be vigilant when encountered with tooth presenting unusual morphology, unilateral missing tooth, and shift in the midline due to early loss of deciduous/permanent canines. Identification of any such dental mutilation practice will need further counselling of the individual and family members. It is the duty of every dental professional to educate and safeguard the oral and dental health of general public.

From stem to roots: Tissue engineering in endodontics

PubMed Central

Kala, M.; Banthia, Priyank; Banthia, Ruchi

2012-01-01

The vitality of dentin-pulp complex is fundamental to the life of tooth and is a priority for targeting clinical management strategies. Loss of the tooth, jawbone or both, due to periodontal disease, dental caries, trauma or some genetic disorders, affects not only basic mouth functions but aesthetic appearance and quality of life. One novel approach to restore tooth structure is based on biology: regenerative endodontic procedure by application of tissue engineering. Regenerative endodontics is an exciting new concept that seeks to apply the advances in tissue engineering to the regeneration of the pulp-dentin complex. The basic logic behind this approach is that patient-specific tissue-derived cell populations can be used to functionally replace integral tooth tissues. The development of such ‘test tube teeth’ requires precise regulation of the regenerative events in order to achieve proper tooth size and shape, as well as the development of new technologies to facilitate these processes. This article provides an extensive review of literature on the concept of tissue engineering and its application in endodontics, providing an insight into the new developmental approaches on the horizon. Key words:Regenerative, tissue engineering, stem cells, scaffold. PMID:24558528

A difference in perspective--the North American and European interpretations of tooth wear.

PubMed

Bartlett, D; Phillips, K; Smith, B

1999-01-01

There is considerable interest in the European dental research literature about the problem of tooth wear and specifically about dental erosion, but this interest does not appear to be matched in North America based on the volume of the literature there. The purpose of this article is to consider the possible explanations for this difference. This article examines the reasons for this disparity and attempts to explain the difference by reviewing the North American and European literature on the etiology, pathogenesis, and prevalence of tooth wear. It would appear from the literature that the reason for the difference in interest between the 2 continents is a reflection of how the appearance, etiology, and terminology are interpreted and used to define tooth wear, attrition, and erosion. Attrition is the wear of teeth against teeth; therefore, by definition any worn surface that does not contact the opposing tooth must have another etiology. An appropriate descriptive term is "tooth wear" when the etiology is multifactorial or cannot be determined. A search of the literature shows more studies in the European literature of the etiology and prevalence of tooth wear than in the North American literature. The thrust of the European studies supports the view that erosion is more important than attrition in the etiology of tooth wear.

Flexibility effects on tooth contact location in spiral bevel gear transmissions

NASA Technical Reports Server (NTRS)

Altidis, P. C.; Savage, M.

1987-01-01

An analytical method to predict the shift of the contact ellipse between the meshing teeth in a spiral bevel gear set is presented in this report. The contact ellipse shift of interest is the motion of the nominal tooth contact location on each tooth from the ideal pitch point to the point of contact between the two teeth considering the elastic motions of the gears and their supporting shafts. This is the shift of the pitch point from the ideal, unloaded position on each tooth to the nominal contact location on the tooth when the gears are fully loaded. It is assumed that the major contributors of this motion are the elastic deflections of the gear shafts, the slopes of the shafts under load and the radial deflections of the four gear shaft bearings. The motions of the two pitch point locations on the pinion and the gear tooth surfaces are calculated in a FORTRAN program which also calculates the size and orientation of the Hertzian contact ellipse on the tooth faces. Based on the curvatures of the two spiral bevel gear teeth and the size of the contact ellipse, the program also predicts the basic dynamic capacity of the tooth pair. A complete numerical example is given to illustrate the use of the program.

Microabrasion in tooth enamel discoloration defects: three cases with long-term follow-ups

PubMed Central

SUNDFELD, Renato Herman; SUNDFELD-NETO, Daniel; MACHADO, Lucas Silveira; FRANCO, Laura Molinar; FAGUNDES, Ticiane Cestari; BRISO, André Luiz Fraga

2014-01-01

Superficial irregularities and certain intrinsic stains on the dental enamel surfaces can be resolved by enamel microabrasion, however, treatment for such defects need to be confined to the outermost regions of the enamel surface. Dental bleaching and resin-based composite repair are also often useful for certain situations for tooth color corrections. This article presented and discussed the indications and limitations of enamel microabrasion treatment. Three case reports treated by enamel microabrasion were also presented after 11, 20 and 23 years of follow-ups. PMID:25141208

The worn dentition--pathognomonic patterns of abrasion and erosion.

PubMed

Abrahamsen, Thomas C

2005-01-01

Historically, the dental literature has revealed various causes of tooth wear, yet it has failed to provide a conclusive method of differentiation and diagnosis of the condition. The categories of tooth wear encountered most commonly in dental practice are abrasion and erosion. The major causes of wear from abrasion are bruxism and toothpaste abuse, and the major causes of wear from erosion are regurgitation, coke-swishing and fruit-mulling. Through in-depth clinical study of these causes, this paper provides a diagnostic system that will enable dental professionals to determine and differentiate the exact aetiology of the worn dentition simply by the recognition of the pathognomonic wear patterns on diagnostic casts, which are based upon the position and quantity of the non-carious loss of tooth structure.

The evolution of tooth wear indices

PubMed Central

2008-01-01

Tooth wear—attrition, erosion and abrasion—is perceived internationally as an ever-increasing problem. Clinical and epidemiological studies, however, are difficult to interpret and compare due to differences in terminology and the large number of indices that have been developed for diagnosing, grading and monitoring dental hard tissue loss. These indices have been designed to identify increasing severity and are usually numerical. Some record lesions on an aetiological basis (e.g. erosion indices), others record lesions irrespective of aetiology (tooth wear indices); none have universal acceptance, complicating the evaluation of the true increase in prevalence reported. This article considers the ideal requirements for an erosion index. It reviews the literature to consider how current indices have evolved and discusses if these indices meet the clinical and research needs of the dental profession. PMID:17701430

Dentinal permeation modeling

NASA Astrophysics Data System (ADS)

Trunina, Natalia; Derbov, Vladimir; Tuchin, Valery; Altshuler, Gregory

2008-06-01

Dentinal permeation is of interest in a wide context of tooth care and treatment, in particular, tooth color improvement using combination of chemical whitening agents and light activation. A simple model of dentinal permeation accounting for the morphology of human tooth dentine and including dentinal tubules, more dense and homogeneous peritubular dentine, and less dense and less homogeneous intertubular dentin is proposed. Calculation of permeability of dentine layer is carried out for H IIO and H IIO II versus the tubule diameter and tubule density taken from the microphotograph analysis. This opens the possibility to calculate the distribution of permeability over the tooth surface taking into account the variations of tubule diameter and density as well as those of the diffusion coefficients and layer thickness

An In-vitro Comparison of Force Loss of Orthodontic Non-Latex Elastics

PubMed Central

Alavi, Shiva; Tabatabaie, Atusa Rahnama; Hajizadeh, Fatemeh; Ardekani, Alireza Haerian

2014-01-01

Objective: The amount and consistency of the applied forces to the tooth are important factors in tooth movements; therefore, the aim of this study was to compare the initial force and the force loss of three brands of elastics in 24 hours. Materials and Methods: In this in-vitro study sixty non-latex elastics (3/16 medium) from three companies (Forestadent, Dentaurum and Ortho Technology) were randomly selected. Two static tests were performed, the first in a dry environment to evaluate the initial force and the other performed in a wet environment (artificial saliva) to evaluate the force loss in 24 hours. The Universal testing machine measured the forces after stretching the elastics to three times the lumen diameter. Data were analyzed by repeated measures ANOVA, One-way ANOVA, Tukey-HSD, Paired samples test, and one sample test. Results: The difference between the brands was significant (p=0.002). Force loss was observed in all samples; 4–7.5% force loss occurred after one hour and 19–38% force loss occurred after 24 hours. The average initial force of Forestadent and Ortho Technology was significantly higher than marketed forces (p<0.001), but the initial force of Dentaurum elastics was similar to the marketed force. Conclusion: The force loss over 24 hours time period was Forestadent>Dentaurum>Ortho-Technology. According to the initial force and force loss percentage it is suggested to replace the non-latex elastics several times a day. PMID:24910671

Molar loss and powder diet leads to memory deficit and modifies the mRNA expression of brain-derived neurotrophic factor in the hippocampus of adult mice.

PubMed

Takeda, Yosuke; Oue, Hiroshi; Okada, Shinsuke; Kawano, Akira; Koretake, Katsunori; Michikawa, Makoto; Akagawa, Yasumasa; Tsuga, Kazuhiro

2016-12-05

It is known that tooth loss is known to be a risk factor for Alzheimer's disease and soft diet feeding induces memory impairment. Recent studies have shown that brain-derived neurotrophic factor (BDNF) is associated with tooth loss or soft diet in young animal model, and that BDNF expression is decreased in patients with Alzheimer's disease. However, single or combined effect of tooth loss and/or soft diet on brain function has not fully understood. Here we examined the effect of molar loss and powder diet on memory ability and the expression of BDNF mRNA in the hippocampus of adult C57BL/6J mice. Twenty eight-weeks-old C57BL/6J mice were divided into intact molar group and extracted molar group. They were randomly divided into the I/S group (Intact upper molar teeth/Solid diet feeding), the E/S group (Extracted upper molar teeth/Solid diet feeding), the I/P group (Intact upper molar teeth/Powder diet feeding), and the E/P group (Extracted upper molar teeth/Powder diet feeding). The observation periods were 4 and 16-week. To analyze the memory ability, the step-through passive avoidance test was conducted. BDNF-related mRNA in the hippocampus was analyzed by real-time polymerase chain reaction (RT-PCR). At 4 weeks later, we performed memory test and isolated brains to analyze. There were no differences in memory function and BDNF mRNA level between these four groups. However, at 16 weeks later, E/S and E/P group showed memory impairment, and decreased level of BDNF mRNA. Whereas, the powder diet had no effect on memory function and BDNF mRNA level even at 16 weeks later. These results suggest that the effect of molar loss and powder diet on memory function and BDNF mRNA levels were different, molar loss may have a greater long-term effect on memory ability than powder diet does.

Research of grinding process of gears with involute profile to increase its efficiency

NASA Astrophysics Data System (ADS)

Ivanova, T. N.; Korshunov, A. I.; Sannikov, I. N.; Tyukpiekov, V. N.

2018-03-01

Grinding as final processing exerts great influence on quality and accuracy of a surface layer of gears. Gear grinding is the most productive method of abrasive processing providing gears of 3 - 8 degrees of accuracy. However violation of the temperature condition of grinding leads to emergence of burns on the surfaces of gears. Therefore the research of the reasons generating defects and finding the ways of their elimination are relevant. The work presents the research of involute tooth profile grinding by wheels of different types with different ways to form a surface. For every way the movements of a tool and a workpiece in order to receive a contour of the tooth socket are simulated. The advantages and the shortcomings of the tooth grinding using form wheels in a grinding method and using dish, worm wheels in generating the grinding method are revealed. The experience of gear production shows that availability of burns in the certain part of a tooth profile is caused by features of the gear grinding process. Theoretical and experimental researches of the thermal phenomena of gear grinding with different configurations of spots in a contact zone and a trajectory of their movement are conducted. There are recommendations how to choose grinding modes, characteristics of abrasive tools taking into account a non-burnt condition of a working surface of a gear. The right choice of lubricating fluid and the way of its supply greatly affect the efficiency of the gear grinding process. It is established that lubricating fluid with special additives gives the best results to obtain desired roughness of a processed surface. The recommendations of effective fluids and their foreign analogs are made.

An automatic tooth preparation technique: A preliminary study

NASA Astrophysics Data System (ADS)

Yuan, Fusong; Wang, Yong; Zhang, Yaopeng; Sun, Yuchun; Wang, Dangxiao; Lyu, Peijun

2016-04-01

The aim of this study is to validate the feasibility and accuracy of a new automatic tooth preparation technique in dental healthcare. An automatic tooth preparation robotic device with three-dimensional motion planning software was developed, which controlled an ultra-short pulse laser (USPL) beam (wavelength 1,064 nm, pulse width 15 ps, output power 30 W, and repeat frequency rate 100 kHz) to complete the tooth preparation process. A total of 15 freshly extracted human intact first molars were collected and fixed into a phantom head, and the target preparation shapes of these molars were designed using customised computer-aided design (CAD) software. The accuracy of tooth preparation was evaluated using the Geomagic Studio and Imageware software, and the preparing time of each tooth was recorded. Compared with the target preparation shape, the average shape error of the 15 prepared molars was 0.05-0.17 mm, the preparation depth error of the occlusal surface was approximately 0.097 mm, and the error of the convergence angle was approximately 1.0°. The average preparation time was 17 minutes. These results validated the accuracy and feasibility of the automatic tooth preparation technique.

Use of quantitative light-induced fluorescence to monitor tooth whitening

NASA Astrophysics Data System (ADS)

Amaechi, Bennett T.; Higham, Susan M.

2001-04-01

The changing of tooth shade by whitening agents occurs gradually. Apart from being subjective and affected by the conditions of the surroundings, visual observation cannot detect a very slight change in tooth color. An electronic method, which can communicate the color change quantitatively, would be more reliable. Quantitative Light- induced Fluorescence (QLF) was developed to detect and assess dental caries based on the phenomenon of change of autofluorescence of a tooth by demineralization. However, stains on the tooth surface exhibit the same phenomenon, and therefore QLF can be used to measure the percentage fluorescence change of stained enamel with respect to surrounding unstained enamel. The present study described a technique of assessing the effect of a tooth-whitening agent using QLF. This was demonstrated in two experiments in which either wholly or partially stained teeth were whitened by intermittent immersion in sodium hypochlorite. Following each immersion, the integrated fluorescence change due to the stain was quantified using QLF. In either situation, the value of (Delta) Q decreased linearly as the tooth regained its natural shade. It was concluded that gradual changing of the shade of discolored teeth by a whitening agent could be quantified using QLF.

An automatic tooth preparation technique: A preliminary study.

PubMed

Yuan, Fusong; Wang, Yong; Zhang, Yaopeng; Sun, Yuchun; Wang, Dangxiao; Lyu, Peijun

2016-04-29

The aim of this study is to validate the feasibility and accuracy of a new automatic tooth preparation technique in dental healthcare. An automatic tooth preparation robotic device with three-dimensional motion planning software was developed, which controlled an ultra-short pulse laser (USPL) beam (wavelength 1,064 nm, pulse width 15 ps, output power 30 W, and repeat frequency rate 100 kHz) to complete the tooth preparation process. A total of 15 freshly extracted human intact first molars were collected and fixed into a phantom head, and the target preparation shapes of these molars were designed using customised computer-aided design (CAD) software. The accuracy of tooth preparation was evaluated using the Geomagic Studio and Imageware software, and the preparing time of each tooth was recorded. Compared with the target preparation shape, the average shape error of the 15 prepared molars was 0.05-0.17 mm, the preparation depth error of the occlusal surface was approximately 0.097 mm, and the error of the convergence angle was approximately 1.0°. The average preparation time was 17 minutes. These results validated the accuracy and feasibility of the automatic tooth preparation technique.

The effect of dentinal fluid flow during loading in various directions--simulation of fluid-structure interaction.

PubMed

Su, Kuo-Chih; Chang, Chih-Han; Chuang, Shu-Fen; Ng, Eddie Yin-Kwee

2013-06-01

This study uses a fluid-structure interaction (FSI) simulation to evaluate the fluid flow in a dental intrapulpal chamber induced by the deformation of the tooth structure during loading in various directions. The FSI is used for the biomechanics simulation of dental intrapulpal responses with the force loading gradually increasing from 0 to 100N at 0°, 30°, 45°, 60°, and 90° on the tooth surface in 1s, respectively. The effect of stress or deformation on tooth and fluid flow changes in the pulp chamber are evaluated. A horizontal loading force on a tooth may induce tooth structure deformation, which increases fluid flow velocity in the coronal pulp. Thus, horizontal loading on a tooth may easily induce tooth pain. This study suggests that experiments to investigate the relationship between loading in various directions and dental pain should avoid measuring the bulk pulpal fluid flow from radicular pulp, but rather should measure the dentinal fluid flow in the dentinal tubules or coronal pulp. The FSI analysis used here could provide a powerful tool for investigating problems with coupled solid and fluid structures in dental biomechanics. Copyright © 2012 Elsevier Ltd. All rights reserved.

Tooth loss, pancreatic cancer, and Helicobacter pylori.

PubMed

Stolzenberg-Solomon, Rachael Z; Dodd, Kevin W; Blaser, Martin J; Virtamo, Jarmo; Taylor, Philip R; Albanes, Demetrius

2003-07-01

Poor dental health has been associated with increased risks of oral, esophageal, and gastric cancer and may also be associated with pancreatic cancer. In addition, Helicobacter pylori has been found in dental plaque and has been associated with periodontal disease and pancreatic cancer. The objective was to investigate prospectively the relation between dentition history and pancreatic cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort in Finland and the association between dentition history and H. pylori seropositivity in a cross-sectional sample of subjects without cancer (n = 475) from the same cohort. Of the 29,104 male smokers aged 50-69 y in the cohort for whom there were complete data, 174 developed pancreatic cancer from 1985 to 1997. Cox proportional hazard models were used to estimate age-, smoking-, education-, urban living-, and height-adjusted hazard ratios and 95% CIs for pancreatic cancer, and logistic regression models were used to estimate age- and education-adjusted odds ratios for H. pylori carriage. Tooth loss was positively associated with pancreatic cancer (edentulous compared with missing 0-10 teeth: hazard ratio = 1.63; 95% CI: 1.09, 2.46; P for trend = 0.02) but was not significantly associated with H. pylori seropositivity (edentulous compared with missing 0-10 teeth: odds ratio = 1.30; 95% CI: 0.73, 2.32; P for trend = 0.37). Additional studies are needed to evaluate the association between tooth loss and pancreatic cancer, as well as cancers at other gastrointestinal sites, particularly with respect to possible biological mechanisms.

Wear of primary teeth caused by opposed all-ceramic or stainless steel crowns

PubMed Central

Bae, Ik-Hyun; Noh, Tae-Hwan; Ju, Sung-Won; Lee, Tae-Kyoung; Ahn, Jin-Soo; Jeong, Tae-Sung

2016-01-01

PURPOSE This study was conducted to evaluate the effects of full-coverage all-ceramic zirconia, lithium disilicate glass-ceramic, leucite glass-ceramic, or stainless steel crowns on antagonistic primary tooth wear. MATERIALS AND METHODS There were four study groups: the stainless steel (Steel) group, the leucite glass-ceramic (Leucite) group, the lithium disilicate glass-ceramic (Lithium) group, and the monolithic zirconia (Zirconia) group. Ten flat crown specimens were prepared per group; opposing teeth were prepared using primary canines. A wear test was conducted over 100,000 chewing cycles using a dual-axis chewing simulator and a 50 N masticating force, and wear losses of antagonistic teeth and restorative materials were calculated using a three-dimensional profiling system and an electronic scale, respectively. Statistical significance was determined using One-way ANOVA and Tukey's test (P<.05). RESULTS The Leucite group (2.670±1.471 mm3) showed the greatest amount of antagonist tooth wear, followed by in decreasing order by the Lithium (2.042±0.696 mm3), Zirconia (1.426±0.477 mm3), and Steel groups (0.397±0.192 mm3). Mean volume losses in the Leucite and Lithium groups were significantly greater than in the Steel group (P<.05). No significant difference was observed between mean volume losses in the Zirconia and Steel groups (P>.05). CONCLUSION Leucite glass-ceramic and lithium disilicate glass-ceramic cause more primary tooth wear than stainless steel or zirconia. PMID:26949487

Tooth loss and its association with dietary intake and diet quality in American adults.

PubMed

Zhu, Yong; Hollis, James H

2014-11-01

To investigate associations between the number of natural teeth and energy intake, nutrient intake, and diet quality in adults. Eligible adults who participated in the National Health and Nutrition Examination Survey during 2005-2008 were included in the present study (n=9140). Participants were classified into three groups depending on the total number of natural teeth (excluding third molars): full dentition (28 teeth), moderate dentition (21-27 teeth), and poor dentition (20 teeth or less). Dietary intake and diet quality were estimated from the first 24-h dietary recall data. Participants in the poor dentition group had significantly lower energy intake than those with moderate dentition (P<0.05), however, both groups did not significantly differ from those who had full dentition. Adjusting for sociodemographic characteristics, physical activity, smoking status, and energy intake, the intake of protein as well as most vitamins and minerals were positively associated with the total number of natural teeth (P<0.05); an inverse association was observed for carbohydrate intake (P<0.001). Diet quality, as measured by the Healthy Eating Index 2005, was inversely associated with tooth loss (P<0.001). Tooth loss in adults is associated with lower diet quality and reduced intake of most nutrients; this may partly explain for the higher risk of chronic diseases in this population. People with missing teeth are recommended to monitor their dietary intake to avoid nutrient deficiency and to improve their diet quality for better health. Copyright © 2014 Elsevier Ltd. All rights reserved.

The prevalence of crowding, attrition, midline discrepancies and premature tooth loss in the primary dentition of children in Jeddah, Saudi Arabia.

PubMed

Alamoudi, N

1999-01-01

The aim of the present study is to evaluate the prevalence of crowding, attrition, midline discrepancies and premature loss of primary molars in primary dentition of children resident in Jeddah, Saudi Arabia. Five hundred and two (502) children aged 4-6 years old residing in the city of Jeddah, Saudi Arabia provide the data for the analysis. Crowding was found in 14.7% of the subjects crowding in the maxilla occurred in 27 (5.4%) of the children, and 67 (13.4%) in the mandible. Simultaneous crowding in maxilla and mandible was present in 20 (3.98%) of the subject. The prevalence of crowding was significantly higher in the mandible than the maxilla (P > 0.01) and higher in male (P < 0.05). Midline shift was present in 10% of the children with females showing a significantly higher prevalence than the males (P < 0.001). Attrition was present in 167 (33.3%) of the children. One hundred and sixty children (31.9%) had attrition in enamel, and only 7(1.4%) had attrition, which exposed the dentin. Thirty-one (6.2%) out of 502 children had 51 (0.5%) missing teeth out of total number of 10,040 teeth. Tooth #84 was most commonly lost tooth (P < .025). Overall premature loss of 1st primary molars was found to be significantly higher than 2nd primary molars (P < .001).

A novel mouse model carrying a human cytoplasmic dynein mutation shows motor behavior deficits consistent with Charcot-Marie-Tooth type 2O disease.

PubMed

Sabblah, Thywill T; Nandini, Swaran; Ledray, Aaron P; Pasos, Julio; Calderon, Jami L Conley; Love, Rachal; King, Linda E; King, Stephen J

2018-01-29

Charcot-Marie-Tooth disease (CMT) is a peripheral neuromuscular disorder in which axonal degeneration causes progressive loss of motor and sensory nerve function. The loss of motor nerve function leads to distal muscle weakness and atrophy, resulting in gait problems and difficulties with walking, running, and balance. A mutation in the cytoplasmic dynein heavy chain (DHC) gene was discovered to cause an autosomal dominant form of the disease designated Charcot-Marie-Tooth type 2 O disease (CMT2O) in 2011. The mutation is a single amino acid change of histidine into arginine at amino acid 306 (H306R) in DHC. In order to understand the onset and progression of CMT2, we generated a knock-in mouse carrying the corresponding CMT2O mutation (H304R/+). We examined H304R/+ mouse cohorts in a 12-month longitudinal study of grip strength, tail suspension, and rotarod assays. H304R/+ mice displayed distal muscle weakness and loss of motor coordination phenotypes consistent with those of individuals with CMT2. Analysis of the gastrocnemius of H304R/+ male mice showed prominent defects in neuromuscular junction (NMJ) morphology including reduced size, branching, and complexity. Based on these results, the H304R/+ mouse will be an important model for uncovering functions of dynein in complex organisms, especially related to CMT onset and progression.

All-optical photoacoustic imaging and detection of early-stage dental caries

NASA Astrophysics Data System (ADS)

Sampathkumar, Ashwin; Hughes, David A.; Longbottom, Chris; Kirk, Katherine J.

2015-02-01

Dental caries remain one of the most common oral diseases in the world. Current detection methods, such as dental explorer and X-ray radiography, suffer from poor sensitivity and specificity at the earliest (and reversible) stages of the disease because of the small size (< 100 microns) of early-stage lesions. We have developed a fine-resolution (480 nm), ultra-broadband (1 GHz), all-optical photoacoustic imaging (AOPAI) system to image and detect early stages of tooth decay. This AOPAI system provides a non-contact, non-invasive and non-ionizing means of detecting early-stage dental caries. Ex-vivo teeth exhibiting early-stage, white-spot lesions were imaged using AOPAI. Experimental scans targeted each early-stage lesion and a reference healthy enamel region. Photoacoustic (PA) signals were generated in the tooth using a 532-nm pulsed laser and the light-induced broadband ultrasound signal was detected at the surface of the tooth with an optical path-stabilized Michelson interferometer operating at 532 nm. The measured time-domain signal was spatially resolved and back-projected to form 2D and 3D maps of the lesion using k-wave reconstruction methods. Experimental data collected from areas of healthy and diseased enamel indicate that the lesion generated a larger PA response compared to healthy enamel. The PA-signal amplitude alone was able to detect a lesion on the surface of the tooth. However, time- reversal reconstructions of the PA scans also quantitatively depicted the depth of the lesion. 3D PA reconstruction of the diseased tooth indicated a sub-surface lesion at a depth of 0.6 mm, in addition to the surface lesion. These results suggest that our AOPAI system is well suited for rapid clinical assessment of early-stage dental caries. An overview of the AOPAI system, fine-resolution PA and histology results of diseased and healthy teeth will be presented.

Evaluation of primary tooth enamel surface morphology and microhardness after Nd:YAG laser irradiation and APF gel treatment--an in vitro study.

PubMed

Banda, Naveen Reddy; Vanaja Reddy, G; Shashikiran, N D

2011-01-01

Laser irradiation and fluoride has been used as a preventive tool to combat dental caries in permanent teeth, but little has been done for primary teeth which are more prone to caries. The purpose of this study was to evaluate microhardness alterations in the primary tooth enamel after Nd-YAG laser irradiation alone and combined with topical fluoride treatment either before or after Nd-YAG laser irradiation. Ten primary molars were sectioned and assigned randomly to: control group, Nd-YAG laser irradiation, Nd-YAG lasing before APF and APF followed by Nd-YAG lasing. The groups were evaluated for microhardness. Surface morphological changes were observed using SEM. Statistical comparisons were performed. The control group's SEM showed a relatively smooth enamel surface and lasing group had fine cracks and porosities. In the lasing + fluoride group a homogenous confluent surface was seen. In the fluoride + lasing group an irregular contour with marked crack propagation was noted. There was a significant increase in the microhardness of the treatment groups. Nd-YAG laser irradiation and combined APF treatment of the primary tooth enamel gave morphologically hardened enamel surface which can be a protective barrier against a cariogenic attack.

Mechanical behavior of CAD/CAM occlusal ceramic reconstruction assessed by digital color holography.

PubMed

Xia, H; Picart, P; Montresor, S; Guo, R; Li, J C; Yusuf Solieman, O; Durand, J-C; Fages, M

2018-05-21

CAD/CAM ceramic occlusal veneers are increasingly used as therapeutic options. However, little is known about their mechanical behavior under stress, as the response of the prepared tooth that supports it. The aim of this article is to use for the first time 3D color holography to evaluate the behavior of a molar occlusal veneer under stress and the response of the prepared tooth. The occlusal surface of a lower molar is prepared to receive a specific monolithic ceramic reconstruction manufactured with a chairside CAD/CAM system. Longitudinally cut samples are used to get a planar object observation and to "look inside" the tooth. A digital holographic set-up permits to obtain the contact-less and one-shot measurement of the three-dimensional displacement field at the surface of the tooth sample; stain fields are evaluated with low noise-sensitive computation. Figures show the strain fields with micro-strain units and highlight the behavior of the ROI (region of interest) in the three directions of space. The ROI are: the ceramic, the glue junction, the dentin enamel junction, dentin and enamel. The results show an excellent behavior of the restored tooth without areas of excessive stress concentrations, but also a significant involvement of the dentin enamel junction. The ceramic occlusal veneer seems to behave in accordance with the biomechanical concepts ensuring the longevity of the reconstituted tooth. 3D holography is a highly recommended method for studying dental biomechanics. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

A Proposed Methodology to Assess the Accuracy of 3D Scanners and Casts and Monitor Tooth Wear Progression in Patients.

PubMed

Ahmed, Khaled E; Whitters, John; Ju, Xiangyang; Pierce, S Gareth; MacLeod, Charles N; Murray, Colin A

2016-01-01

The aim of this study was to detail and assess the capability of a novel methodology to 3D-quantify tooth wear progression in a patient over a period of 12 months. A calibrated stainless steel model was used to identify the accuracy of the scanning system by assessing the accuracy and precision of the contact scanner and the dimensional accuracy and stability of casts fabricated from three different types of impression materials. Thereafter, the overall accuracy of the 3D scanning system (scanner and casts) was ascertained. Clinically, polyether impressions were made of the patient's dentition at the initial examination and at the 12-month review, then poured in type IV dental stone to assess the tooth wear. The anterior teeth on the resultant casts were scanned, and images were analyzed using 3D matching software to detect dimensional variations between the patient's impressions. The accuracy of the 3D scanning system was established to be 33 μm. 3D clinical analysis demonstrated localized wear on the incisal and palatal surfaces of the patient's maxillary central incisors. The identified wear extended to a depth of 500 μm with a distribution of 4% to 7% of affected tooth surfaces. The newly developed 3D scanning methodology was found to be capable of assessing and accounting for the various factors affecting tooth wear scanning. Initial clinical evaluation of the methodology demonstrates successful monitoring of tooth wear progression. However, further clinical assessment is needed.

Mx1 and Mx2 key antiviral proteins are surprisingly lost in toothed whales

PubMed Central

Braun, Benjamin A.; Marcovitz, Amir; Camp, J. Gray; Jia, Robin; Bejerano, Gill

2015-01-01

Viral outbreaks in dolphins and other Delphinoidea family members warrant investigation into the integrity of the cetacean immune system. The dynamin-like GTPase genes Myxovirus 1 (Mx1) and Mx2 defend mammals against a broad range of viral infections. Loss of Mx1 function in human and mice enhances infectivity by multiple RNA and DNA viruses, including orthomyxoviruses (influenza A), paramyxoviruses (measles), and hepadnaviruses (hepatitis B), whereas loss of Mx2 function leads to decreased resistance to HIV-1 and other viruses. Here we show that both Mx1 and Mx2 have been rendered nonfunctional in Odontoceti cetaceans (toothed whales, including dolphins and orcas). We discovered multiple exon deletions, frameshift mutations, premature stop codons, and transcriptional evidence of decay in the coding sequence of both Mx1 and Mx2 in four species of Odontocetes. We trace the likely loss event for both proteins to soon after the divergence of Odontocetes and Mystocetes (baleen whales) ∼33–37 Mya. Our data raise intriguing questions as to what drove the loss of both Mx1 and Mx2 genes in the Odontoceti lineage, a double loss seen in none of 56 other mammalian genomes, and suggests a hitherto unappreciated fundamental genetic difference in the way these magnificent mammals respond to viral infections. PMID:26080416

Mx1 and Mx2 key antiviral proteins are surprisingly lost in toothed whales.

PubMed

Braun, Benjamin A; Marcovitz, Amir; Camp, J Gray; Jia, Robin; Bejerano, Gill

2015-06-30

Viral outbreaks in dolphins and other Delphinoidea family members warrant investigation into the integrity of the cetacean immune system. The dynamin-like GTPase genes Myxovirus 1 (Mx1) and Mx2 defend mammals against a broad range of viral infections. Loss of Mx1 function in human and mice enhances infectivity by multiple RNA and DNA viruses, including orthomyxoviruses (influenza A), paramyxoviruses (measles), and hepadnaviruses (hepatitis B), whereas loss of Mx2 function leads to decreased resistance to HIV-1 and other viruses. Here we show that both Mx1 and Mx2 have been rendered nonfunctional in Odontoceti cetaceans (toothed whales, including dolphins and orcas). We discovered multiple exon deletions, frameshift mutations, premature stop codons, and transcriptional evidence of decay in the coding sequence of both Mx1 and Mx2 in four species of Odontocetes. We trace the likely loss event for both proteins to soon after the divergence of Odontocetes and Mystocetes (baleen whales) ∼33-37 Mya. Our data raise intriguing questions as to what drove the loss of both Mx1 and Mx2 genes in the Odontoceti lineage, a double loss seen in none of 56 other mammalian genomes, and suggests a hitherto unappreciated fundamental genetic difference in the way these magnificent mammals respond to viral infections.

Dental implants as strategic supplementary abutments for implant-tooth-supported telescopic crown-retained maxillary dentures: a retrospective follow-up study for up to 9 years.

PubMed

Krennmair, Gerald; Krainhöfner, Martin; Waldenberger, Otmar; Piehslinger, Eva

2007-01-01

The aim of this retrospective study was to present the results of implants and natural teeth used as combined abutments to support maxillary telescopic prostheses. Between 1997 and 2004, 22 patients with residual maxillary teeth underwent prosthodontic rehabilitation with supplementary implant placement of implant-tooth-supported telescopic prostheses. A total of 60 supplementary implants (mean: 2.9 implants; SD: 1.6; range: 1 to 5 per patient) were placed in strategic position and connected with 48 natural abutment teeth (mean: 2.2 teeth; SD: 0.9; range: 1 to 4 per patient) using telescopic crowns. The follow-up registration included implant and natural tooth survival rates and peri-implant and periodontal parameters, along with prosthodontic maintenance. Natural tooth abutments were additionally followed to compare their periodontal parameters at baseline to the follow-up examination. After a mean of 38 months (12 to 108 months) no implants or natural tooth abutments were lost (survival rate: 100%). There was no fracture, endodontic treatment, loss, or intrusion of natural teeth used for telescopic abutments. Implant abutments showed high stability and excellent periimplant soft tissue conditions. Natural tooth abutments used for double crowns also showed uneventful progress. A low rate of prosthodontic maintenance was seen, with implant screw abutment loosening as the most severe complication (3 of 60 implants; 5%). On the basis of this retrospective clinical review, the following conclusions were drawn: (1) successful function over a prolonged period and a minor complication rate of implant-tooth-supported telescopic maxillary dentures may be anticipated, and (2) the great variety of treatment modalities offered by tooth-implant support for telescopic prostheses appears to be useful as a treatment option for the maxilla in elderly patients.

Nothing new under the heavens: MIH in the past?

PubMed

Ogden, A R; Pinhasi, R; White, W J

2008-12-01

This was to study an archaeological population of subadult teeth in 17th and 18th century skeletal material from a London (England) cemetery for enamel defects including molar-incisor-hypomineralisation (MIH). Dentitions of 45 sub-adults were examined using standard macroscopic methods and systematically recorded. A total of 557 teeth were examined with a *5 lens and photographed. Ages of the individuals were estimated from their dental crown and root development stages and not from charts that combine tooth eruption with development stages. The dental age of the individual and the approximate age of onset of enamel defects was then calculated on the basis of the chronological sequence of incremental deposition and calcification of the enamel matrix. Affected enamel was graded macroscopically as: - Mild: <30% of the tooth's enamel surface area visibly disrupted (this encompasses the entire range reported in most other studies), Moderate: 31-49% of the tooth's enamel surface area visibly disrupted and Severe: >50% of the tooth's enamel surface area visibly disrupted. Of the total number of individuals 41 (93.2%) showed signs of enamel developmental dysplasia or MIH, 28 of them showing moderate or severe lesions of molars, primary or permanent (63.6% of the sample). Incisors and canines, though surviving much less often, showed episodes of linear hypoplasia. The extensive lesions seen on many of the molars displayed cuspal enamel hypoplasia (CEH). Many of these teeth also exhibited Molar Incisal Hypomineralisation (MIH).

Genetic Susceptibility to Dental Caries on Pit and Fissure and Smooth Surfaces

PubMed Central

Shaffer, J.R.; Wang, X.; DeSensi, R.S.; Wendell, S.; Weyant, R.J.; Cuenco, K.T.; Crout, R.; McNeil, D.W.; Marazita, M.L.

2012-01-01

Carious lesions are distributed nonuniformly across tooth surfaces of the complete dentition, suggesting that the effects of risk factors may be surface-specific. Whether genes differentially affect caries risk across tooth surfaces is unknown. We investigated the role of genetics on two classes of tooth surfaces, pit and fissure surfaces (PFS) and smooth surfaces (SMS), in more than 2,600 subjects from 740 families. Participants were examined for surface-level evidence of dental caries, and caries scores for permanent and/or primary teeth were generated separately for PFS and SMS. Heritability estimates (h2, i.e. the proportion of trait variation due to genes) of PFS and SMS caries scores were obtained using likelihood methods. The genetic correlations between PFS and SMS caries scores were calculated to assess the degree to which traits covary due to common genetic effects. Overall, the heritability of caries scores was similar for PFS (h2 = 19–53%; p < 0.001) and SMS (h2 = 17–42%; p < 0.001). Heritability of caries scores for both PFS and SMS in the primary dentition was greater than in the permanent dentition and total dentition. With one exception, the genetic correlation between PFS and SMS caries scores was not significantly different from 100%, indicating that (mostly) common genes are involved in the risk of caries for both surface types. Genetic correlation for the primary dentition dfs (decay + filled surfaces) was significantly less than 100% (p < 0.001), indicating that genetic factors may exert differential effects on caries risk in PFS versus SMS in the primary dentition. PMID:22286298