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Sample records for dental amalgam fillings

  1. About Dental Amalgam Fillings

    MedlinePlus

    ... documents in the Related Resources section. Why is mercury used in dental amalgam? Approximately half of a ... about bioaccumulation, please see Related Resources. Is the mercury in dental amalgam the same as the mercury ...

  2. Dental Amalgam

    MedlinePlus

    ... Products and Medical Procedures Dental Devices Dental Amalgam Dental Amalgam Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Dental amalgam is a dental filling material which is ...

  3. Mercury Exposure Levels in Children with Dental Amalgam Fillings

    PubMed Central

    Miriam Varkey, Indu; Shetty, Rajmohan; Hegde, Amitha

    2014-01-01

    ABSTRACT% Objectives: Mercury combined with other metals to form solid amalgams has long been used in reconstructive dentistry but its use has been controversial since at least the middle of the 19th century. The exposure and body burden of mercury reviews have consistently stated that there is a deficiency of adequate epidemiological studies addressing this issue. Fish and dental amalgam are two major sources of human exposure to organic (MeHg) and inorganic Hg respectively. Materials and methods: A total of 150 subjects aged between 9 and 14 years were divided into two groups of 75 subjects each depending on their diet, i.e. seafood or nonseafood consuming. Each category was subdivided into three groups based on number of restorations. Scalp hair and urine samples were collected at baseline and 3 months later to assess the organic and inorganic levels of mercury respectively by atomic absorption spectrophotometer (AAS). Results: The mean values of urinary mercury (inorganic mercury) in the group of children with restorations were 1.5915 μg/l as compared to 0.0130 μg/l in the groups with no amalgam restorations (p < 0.001) (Wilcoxon sign rank test and paired t-test). The hair mercury levels (organic mercury) varied signi-ficantly between the fsh-eating group and nonfsh-eating group, the average values being 1.03 μg/l and 0.84 μg/l respectively (p < 0.001) (Mann-Whitney U-test and paired t-test). Conclusion and significance: The notion about the mercury being released from the amalgam restorations as a sole exposure source needs to be put to a rest, as environmental factors collectively overpower the exposure levels from restorations alone. How to cite this article: Varkey IM, Shetty R, Hegde A. Mercury Exposure Levels in Children with Dental Amalgam Fillings. Int J Clin Pediatr Dent 2014;7(3):180-185. PMID:25709298

  4. Maternal-fetal distribution of mercury ( sup 203 Hg) released from dental amalgam fillings

    SciTech Connect

    Vimy, M.J.; Takahashi, Y.; Lorscheider, F.L. )

    1990-04-01

    In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered.

  5. High-field MRI and mercury release from dental amalgam fillings.

    PubMed

    Mortazavi, S M J; Neghab, M; Anoosheh, S M H; Bahaeddini, N; Mortazavi, G; Neghab, P; Rajaeifard, A

    2014-04-01

    Mercury is among the most toxic nonradioactive elements which may cause toxicity even at low doses. Some studies showed release of mercury from dental amalgam fillings in individuals who used mobile phone. This study was conducted to assess the effect of high-field MRI on mercury release from dental amalgam filling. We studied two groups of students with identical tooth decays requiring a similar pattern of restorative dentistry. They were exposed to a magnetic flux density of 1.5 T produced by a MRI machine. 16 otherwise healthy students with identical dental decay participated in this study. They underwent similar restorative dentistry procedures and randomly divided into two groups of MRI-exposed and control arms. Urinary concentrations of mercury in the control subjects were measured before (hour 0) and 48 and 72 hrs after amalgam restoration, using cold vapor atomic absorption spectrometry. Urinary concentrations of mercury in exposed individuals were determined before (hour 0), and 24, 48, 72 and 96 hrs after amalgam restoration. Unlike control subjects, they underwent conventional brain MRI (15 min, 99 slices), 24 hrs after amalgam restoration. The mean±SD urinary mercury levels in MRI-exposed individuals increased linearly from a baseline value of 20.70±17.96 to 24.83±22.91 μg/L 72 hrs after MRI. In the control group, the concentration decreased linearly from 20.70±19.77 to 16.14±20.05 μg/L. The difference between urinary mercury in the exposed and control group, 72 hrs after MRI (96 h after restoration),was significant (p=0.046). These findings provide further support for the noxious effect of MRI (exposure to strong magnetic field)and release of mercury from dental amalgam fillings.

  6. Effect of mercury (Hg) dental amalgam fillings on renal and oxidative stress biomarkers in children.

    PubMed

    Al-Saleh, Iman; Al-Sedairi, Al anoud; Elkhatib, Rola

    2012-08-01

    We examined the effect of mercury (Hg) associated with dental amalgam fillings on biomarkers of renal and oxidative stress in children between the ages of 5-15.5 years. Urine samples were analyzed for N-acetyl-β-D-glucosaminidase (NAG), α(1)-microglobulin (α(1)-MG), β(2)-microglobulin (β(2)-MG), retinol binding protein (RBP), albumin (ALB), 8-hydroxy-2-deoxyguanosine (8-OHdG) and malondialdehyde (MDA). The level of urinary Hg (UHg-C) was calculated as μg/g creatinine. Multiple regression analyses revealed that the excretion of urinary NAG was significantly associated with the presence of dental amalgam fillings (β=0.149, P=0.03) and the levels of UHg-C (β=0.531, P=0), with an interaction between the two (P=0). The increase in urinary NAG in relation to UHg-C levels had a dose-effect pattern. The lowest observed effect was seen at UHg-C levels above 1.452 μg/g creatinine, which is lower than previously reported. In contrast, α(1)-MG was negatively associated with the presence of dental amalgam fillings (β=-0.270, P=0), but positively with UHg-C levels (β=0.393, P=0). There were 7 children without, and one child with, dental amalgam fillings with urinary α(1)-MG levels above the reference limit of >7 mg/g creatinine. Even though α(1)-MG seems to be a reliable biomarker for early changes in renal functions, it might exert its effect only at a higher level of exposure. An inverse relationship was also observed between urinary 8-OHdG levels and the presence of dental amalgam fillings. This might suggest that the dental amalgam does not increase DNA damage but reduces the capacity to repair DNA, leading to lower urinary excretion of 8-OHdG. On the other hand, we found that Hg affected the excretion of urinary 8-OHdG in a dose-related pattern that was mostly associated with long-term exposure to low Hg levels. Urinary NAG levels were positively associated with urinary MDA levels (β=0.516, P=0) but not with 8-OHdG (β=0.134, P=0.078) after adjustment for

  7. [Amalgam fillings and T-lymphocyte changes].

    PubMed

    Giuliani, M; Rumi, C; Marciani, F; Boari, A; Rumi, G; Di Felice, R

    1990-07-01

    Dental amalgam and nickel alloys have been considered quite safe. Previous authors reported the effect of dental amalgam and nickel alloys on human T-lymphocytes modifications after amalgam dental fillings, into dose-dependence of any modifications and into possible temporary. Eight patients were subjected to dental care with amalgam dental fillings. Drawings of blood were executed at start, fifteen days after late fillings and two months later. The results about modifications of T-lymphocytes were not univocal. We believe, at now, that temporary modifications of the immunity seem to be related to a cytotoxic mechanism.

  8. Dental amalgam and mercury

    SciTech Connect

    Mackert, J.R. Jr. )

    1991-08-01

    This paper looks at the issues of the current amalgam controversy: the daily dose of mercury from amalgam, hypersensitivity to mercury, claims of adverse effects from amalgam mercury and alleged overnight 'cures.' In addition, the toxicity and allergenicity of the proposed alternative materials are examined with the same kind of scrutiny applied by the anti-amalgam group to dental amalgam. 100 references.

  9. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  10. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  11. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  12. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  13. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... is intended for filling dental caries. (b) Classification. Class I (general controls). The device is... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A...

  14. Dental amalgam: An update

    PubMed Central

    Bharti, Ramesh; Wadhwani, Kulvinder Kaur; Tikku, Aseem Prakash; Chandra, Anil

    2010-01-01

    Dental amalgam has served as an excellent and versatile restorative material for many years, despite periods of controversy. The authors review its history, summarize the evidence with regard to its performance and offer predictions for the future of this material. The PubMed database was used initially; the reference list for dental amalgam featured 8641 articles and 13 publications dealing with recent advances in dental amalgam. A forward search was undertaken on selected articles and using some author names. For the present, amalgam should remain the material of choice for economic direct restoration of posterior teeth. When esthetic concerns are paramount, tooth-colored materials, placed meticulously, can provide an acceptable alternative. All alternative restorative materials and procedures, however, have certain limitations. PMID:21217947

  15. Association between History of Dental Amalgam Fillings and Risk of Parkinson’s Disease: A Population-Based Retrospective Cohort Study in Taiwan

    PubMed Central

    Hsu, Yung-Chuang; Chang, Cheng-Wei; Lee, Hsin-Lin; Chuang, Chuan-Chung; Chiu, Hsien-Chung; Li, Wan-Yun; Horng, Jorng-Tzong; Fu, Earl

    2016-01-01

    The impact of dental amalgam on the development of Parkinson’s disease (PD) is still uncertain, although a positive association between dental amalgam and PD has been found in a few case-control studies. The patients with amalgam fillings restored between 2000 and 2008 were identified by using the National Health Insurance Research Database (NHIRD) in Taiwan. The same number of patients who had no new amalgam filling restored was matched by sex, age, and treatment date. Both cohorts were followed up from the treatment date until the date of diagnosis of PD, death, or the end of the year 2008. The individuals who received amalgam fillings had a significantly higher risk of PD afterward (adjusted hazard ratio [HR]=1.583, 95% confidence interval [CI]=1.122–2.234, p=0.0089) than those who did not. In the individuals who received amalgam fillings, being diagnosed with diabetes or hyperlipidemia demonstrated a significantly lower HR of PD occurrence than in the patients without diabetes or hyperlipidemia (HR=0.449, 95% CI=0.254–0.794, p=0.0059; HR=0.445, 95% CI=0.260–0.763, p=0.0032) after adjusting for comorbidities and Charlson-Deyo Comorbidity Index (CCI) scores. Meanwhile, hypertension increased the hazard risk of PD (HR=1.645, 95% CI=1.098–2.464, p=0.0159). The patients exposed to dental amalgam fillings were 1.583 times more likely to have PD afterward compared to their non-exposed counterparts after adjusting for comorbidities and CCI scores. PMID:27906991

  16. Association between History of Dental Amalgam Fillings and Risk of Parkinson's Disease: A Population-Based Retrospective Cohort Study in Taiwan.

    PubMed

    Hsu, Yung-Chuang; Chang, Cheng-Wei; Lee, Hsin-Lin; Chuang, Chuan-Chung; Chiu, Hsien-Chung; Li, Wan-Yun; Horng, Jorng-Tzong; Fu, Earl

    2016-01-01

    The impact of dental amalgam on the development of Parkinson's disease (PD) is still uncertain, although a positive association between dental amalgam and PD has been found in a few case-control studies. The patients with amalgam fillings restored between 2000 and 2008 were identified by using the National Health Insurance Research Database (NHIRD) in Taiwan. The same number of patients who had no new amalgam filling restored was matched by sex, age, and treatment date. Both cohorts were followed up from the treatment date until the date of diagnosis of PD, death, or the end of the year 2008. The individuals who received amalgam fillings had a significantly higher risk of PD afterward (adjusted hazard ratio [HR]=1.583, 95% confidence interval [CI]=1.122-2.234, p=0.0089) than those who did not. In the individuals who received amalgam fillings, being diagnosed with diabetes or hyperlipidemia demonstrated a significantly lower HR of PD occurrence than in the patients without diabetes or hyperlipidemia (HR=0.449, 95% CI=0.254-0.794, p=0.0059; HR=0.445, 95% CI=0.260-0.763, p=0.0032) after adjusting for comorbidities and Charlson-Deyo Comorbidity Index (CCI) scores. Meanwhile, hypertension increased the hazard risk of PD (HR=1.645, 95% CI=1.098-2.464, p=0.0159). The patients exposed to dental amalgam fillings were 1.583 times more likely to have PD afterward compared to their non-exposed counterparts after adjusting for comorbidities and CCI scores.

  17. Orofacial granulomatosis related to amalgam fillings.

    PubMed

    Ellison, R; Green, C; Gibson, J; Ghaffar, S

    2013-11-01

    This paper reports on a case of Orofacial Granulomatosis (OFG) in which the presence of amalgam fillings appears to have played a part in the aetiology. Once these restorations were removed and replaced with an alternative composite restorative material, all symptoms and signs of OFG resolved completely. This case highlights the necessity to include dental metals in the patch test battery when performing delayed patch testing on patients with OFG.

  18. Human brain mercury levels related to exposure to amalgam fillings.

    PubMed

    Ertaş, E; Aksoy, A; Turla, A; Karaarslan, E S; Karaarslan, B; Aydın, A; Eken, A

    2014-08-01

    The safety of dental amalgam as the primary material in dental restoration treatments has been debated since its introduction. It is widely accepted that amalgam restorations continuously release elemental mercury (Hg) vapor, which is inhaled and absorbed by the body and distributed to tissues, including the brain. The aim of the present study was to investigate whether the presence of amalgam fillings is correlated with brain Hg level. The Hg levels in the parietal lobes of the brains of 32 cadavers were analyzed with an atomic absorption spectrometer with the mercury hydride system. A total of 32 brain samples were tested; of these, 10 were from cadavers with amalgam fillings, while 22 of them were amalgam free. Hg was detected in 60.0% (6 of 10) of the samples in the amalgam group and in 36.3% (8 of 22) in the amalgam-free group. The average Hg level of the amalgam group was 0.97 ± 0.83 µg/g (minimum: 0.3 µg/g and maximum: 2.34 µg/g), and in the amalgam-free group, it was 1.06 ± 0.57 µg/g (minimum: 0.17 µg/g and maximum: 1.76 µg/g). The results of the present study showed no correlation between the presence of amalgam fillings and brain Hg level.

  19. Mercury in saliva and feces after removal of amalgam fillings.

    PubMed

    Björkman, L; Sandborgh-Englund, G; Ekstrand, J

    1997-05-01

    The toxicological consequences of exposure to mercury (Hg) from dental amalgam fillings is a matter of debate in several countries. The purpose of this study was to obtain data on Hg concentrations in saliva and feces before and after removal of dental amalgam fillings. In addition Hg concentrations in urine, blood, and plasma were determined. Ten subjects had all amalgam fillings removed at one dental session. Before removal, the median Hg concentration in feces was more than 10 times higher than in samples from an amalgam free reference group consisting of 10 individuals (2.7 vs 0.23 mumol Hg/kg dry weight, p < 0.001). A considerable increase of the Hg concentration in feces 2 days after amalgam removal (median 280 mumol Hg/kg dry weight) was followed by a significant decrease. Sixty days after removal the median Hg concentration was still slightly higher than in samples from the reference group. In plasma, the median Hg concentration was 4 nmol/liter at baseline. Two days after removal the median Hg concentration in plasma was increased to 5 nmol/liter and declined subsequently to 1.3 nmol/liter by Day 60. In saliva, there was an exponential decline in the Hg concentration during the first 2 weeks after amalgam removal (t 1/2 = 1.8 days). It was concluded that amalgam fillings are a significant source of Hg in saliva and feces. Hg levels in all media decrease considerably after amalgam removal. The uptake of amalgam mercury in the GI tract in conjunction with removal of amalgam fillings seems to be low.

  20. Increased Zn/Glutathione Levels and Higher Superoxide Dismutase-1 Activity as Biomarkers of Oxidative Stress in Women with Long-Term Dental Amalgam Fillings: Correlation between Mercury/Aluminium Levels (in Hair) and Antioxidant Systems in Plasma

    PubMed Central

    Cabaña-Muñoz, María Eugenia; Parmigiani-Izquierdo, José María; Bravo-González, Luis Alberto; Kyung, Hee-Moon; Merino, José Joaquín

    2015-01-01

    Background The induction of oxidative stress by Hg can affect antioxidant enzymes. However, epidemiological studies have failed to establish clear association between dental fillings presence and health problems. Objectives To determine whether heavy metals (in hair), antioxidant enzymes (SOD-1) and glutathione levels could be affected by the chronic presence of heavy metals in women who had dental amalgam fillings. Materials and Methods 55 hair samples (42 females with amalgam fillings and 13 female control subjects) were obtained. All subjects (mean age 44 years) who had dental amalgam filling for more than 10 years (average 15 years). Certain metals were quantified by ICP-MS (Mass Spectrophotometry) in hair (μg/g: Al, Hg, Ba, Ag, Sb, As, Be, Bi, Cd, Pb, Pt, Tl, Th, U, Ni, Sn, Ti) and SOD-1 and Glutathione (reduced form) levels in plasma. Data were compared with controls without amalgams, and analyzed to identify any significant relation between metals and the total number of amalgam fillings, comparing those with four or less (n = 27) with those with more than four (n = 15). As no significant differences were detected, the two groups were pooled (Amlgam; n = 42). Findings Hg, Ag, Al and Ba were higher in the amalgam group but without significant differences for most of the heavy metals analyzed. Increased SOD-1 activity and glutathione levels (reduced form) were observed in the amalgam group. Aluminum (Al) correlated with glutathione levels while Hg levels correlated with SOD-1. The observed Al/glutathione and Hg/SOD-1 correlation could be adaptive responses against the chronic presence of mercury. Conclusions Hg, Ag, Al and Ba levels increased in women who had dental amalgam fillings for long periods. Al correlated with glutathione, and Hg with SOD-1. SOD-1 may be a possible biomarker for assessing chronic Hg toxicity. PMID:26076368

  1. Critical appraisal: dental amalgam update--part II: biological effects.

    PubMed

    Wahl, Michael J; Swift, Edward J

    2013-12-01

    Dental amalgam restorations have been controversial for over 150 years. In Part I of this Critical Appraisal, the clinical efficacy of dental amalgam was updated. Here in Part II, the biological effects of dental amalgam are addressed.

  2. 75 FR 33169 - Dental Devices: Classification of Dental Amalgam, Reclassification of Dental Mercury, Designation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-11

    ...-AG21 Dental Devices: Classification of Dental Amalgam, Reclassification of Dental Mercury, Designation of Special Controls for Dental Amalgam, Mercury, and Amalgam Alloy; Technical Amendment AGENCY: Food... classified dental amalgam as a class II device, reclassified dental mercury from class I to class II,...

  3. Corrosion Penetration in Crevices of Dental Amalgam.

    DTIC Science & Technology

    1978-09-07

    AD-AC59 301 LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CALIF PA-ETC F/6 A/S .9 CORROSION PENETRATION IN CREVICES OF DENTAL AMALGAM. (U) SEP 78 T...OF RE;-ORT & PERIOD COVERED ./CORROSION PENETRATION IN CREVICES OF _. Itm . / DENTAL AMALGAM, - . .... ,,, T 7 AUTHOR(s) / L S i DG3t1 , T. Katan and...identify by block number) amalgam corrosion, crevice corrosion, dental amalgam. 20.- ABSTRACT (Continue on reverse side If necessary and Identify by

  4. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental amalgam, mercury, and amalgam alloy. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3070 Dental amalgam, mercury... elemental mercury, supplied as a liquid in bulk, sachet, or predosed capsule form, and amalgam...

  5. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental amalgam, mercury, and amalgam alloy. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3070 Dental amalgam, mercury... elemental mercury, supplied as a liquid in bulk, sachet, or predosed capsule form, and amalgam...

  6. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental amalgam, mercury, and amalgam alloy. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3070 Dental amalgam, mercury... elemental mercury, supplied as a liquid in bulk, sachet, or predosed capsule form, and amalgam...

  7. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental amalgam, mercury, and amalgam alloy. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3070 Dental amalgam, mercury... elemental mercury, supplied as a liquid in bulk, sachet, or predosed capsule form, and amalgam...

  8. 21 CFR 872.3070 - Dental amalgam, mercury, and amalgam alloy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgam, mercury, and amalgam alloy. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3070 Dental amalgam, mercury... elemental mercury, supplied as a liquid in bulk, sachet, or predosed capsule form, and amalgam...

  9. Mercury recovery in situ of four different dental amalgam separators.

    PubMed

    Hylander, Lars D; Lindvall, Anders; Uhrberg, Roland; Gahnberg, Lars; Lindh, Ulf

    2006-07-31

    Amalgam separators are used to physically remove dental amalgam from waste water in dental clinics. They are thereby supposed to reduce mercury (Hg) emissions to the municipal waste water system to acceptable levels. We here present results from a comparative study in situ of three amalgam separators available on the market, all with a claimed efficiency of 99% according to Danish and ISO protocols, and using sedimentation as the principle of separation. We also present corresponding data for an investigational prototype of an improved separator. The obtained efficiency of the three commercial separators is far below what is stated by the manufacturer and by authorities assumed to be the efficiency in clinical conditions. They reduced Hg emissions by 79 - 91%, leaving an average Hg content in outgoing waste water of 1.5 mg L(-1). However, the prototype separator participating in this study retained 99.9% of the waste water Hg emissions, leaving an average Hg content in outgoing waste water of 0.004 mg L(-1). Physical restrictions prohibit sedimentary type separators to recover the Hg fractions causing the largest damages in wastewater treatment plants. This fraction is not considered in the ISO protocol for testing amalgam separators, which therefore needs to be revised. Abolishing the use of dental amalgam and cleaning the tubing systems is the most efficient long-term solution to reduce Hg emissions from dental clinics. Until then, Hg emissions originating from placing, polishing or removing existing amalgam fillings, should be counteracted by the use of low-emission amalgam separators, already on the market or presently being developed for use alone or together with sedimentary type amalgam separators.

  10. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification. A dental amalgam capsule is a container device in which silver alloy is intended to be mixed with...

  11. Increased Release of Mercury from Dental Amalgam Fillings due to Maternal Exposure to Electromagnetic Fields as a Possible Mechanism for the High Rates of Autism in the Offspring: Introducing a Hypothesis.

    PubMed

    Mortazavi, Gh; Haghani, M; Rastegarian, N; Zarei, S; Mortazavi, S M J

    2016-03-01

    According to the World Health Organization (WHO), factors such as growing electricity demand, ever-advancing technologies and changes in social behaviour have led to steadily increasing exposure to man-made electromagnetic fields.  Dental amalgam fillings are among the major sources of exposure to elemental mercury vapour in the general population. Although it was previously believed that low levels are mercury (i.g. release of mercury from dental amalgam) is not hazardous, now numerous data indicate that even very low doses of mercury cause toxicity. There are some evidence indicating that perinatal exposure to mercury is significantly associated with an increased risk of developmental disorders such as autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD). Furthermore, mercury can decrease the levels of neurotransmitters dopamine, serotonin, noreprenephrine, and acetylcholine in the brain and cause neurological problems. On the other hand, a strong positive correlation between maternal and cord blood mercury levels is found in some studies. We have previously shown that exposure to MRI or microwave radiation emitted by common mobile phones can lead to increased release of mercury from dental amalgam fillings. Moreover, when we investigated the effects of MRI machines with stronger magnetic fields, our previous findings were confirmed. As a strong association between exposure to electromagnetic fields and mercury level has been found in our previous studies, our findings can lead us to this conclusion that maternal exposure to electromagnetic fields in mothers with dental amalgam fillings may cause elevated levels of mercury and trigger the increase in autism rates. Further studies are needed to have a better understanding of the possible role of the increased mercury level after exposure to electromagnetic fields and the rate of autism spectrum disorders in the offspring.

  12. Increased Release of Mercury from Dental Amalgam Fillings due to Maternal Exposure to Electromagnetic Fields as a Possible Mechanism for the High Rates of Autism in the Offspring: Introducing a Hypothesis

    PubMed Central

    Mortazavi, Gh.; Haghani, M.; Rastegarian, N.; Zarei, S.; Mortazavi, S.M.J.

    2016-01-01

    According to the World Health Organization (WHO), factors such as growing electricity demand, ever-advancing technologies and changes in social behaviour have led to steadily increasing exposure to man-made electromagnetic fields.  Dental amalgam fillings are among the major sources of exposure to elemental mercury vapour in the general population. Although it was previously believed that low levels are mercury (i.g. release of mercury from dental amalgam) is not hazardous, now numerous data indicate that even very low doses of mercury cause toxicity. There are some evidence indicating that perinatal exposure to mercury is significantly associated with an increased risk of developmental disorders such as autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD). Furthermore, mercury can decrease the levels of neurotransmitters dopamine, serotonin, noreprenephrine, and acetylcholine in the brain and cause neurological problems. On the other hand, a strong positive correlation between maternal and cord blood mercury levels is found in some studies. We have previously shown that exposure to MRI or microwave radiation emitted by common mobile phones can lead to increased release of mercury from dental amalgam fillings. Moreover, when we investigated the effects of MRI machines with stronger magnetic fields, our previous findings were confirmed. As a strong association between exposure to electromagnetic fields and mercury level has been found in our previous studies, our findings can lead us to this conclusion that maternal exposure to electromagnetic fields in mothers with dental amalgam fillings may cause elevated levels of mercury and trigger the increase in autism rates. Further studies are needed to have a better understanding of the possible role of the increased mercury level after exposure to electromagnetic fields and the rate of autism spectrum disorders in the offspring. PMID:27026954

  13. Determination of light elements in amalgam restorations. [Dental amalgam

    SciTech Connect

    Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Osborne, J.W.; Nelson, G.V.

    1982-01-01

    Rutherford backscattering has been used to measure the major elemental compositions in the near-surface regions of freshly prepared and used samples of dental amalgam. A depletion from bulk stoichiometry of the major elements, which indicates an accumulation of lighter elements on the surface of the materials, has been observed. Increases in the F, Na, Cl, P, O, C, and N concentrations between freshly prepared samples and used samples were measured by observation of gamma rays produced by proton and deuteron induced reactions.

  14. Dental amalgam: is this the end?

    PubMed

    Taut, Cristina

    Dental amalgam is a reliable and effective restorative material with a well-established role in modern dentistry. Throughout the years its mercury content and the risks posed to human health were main topics of interest for many scientists. This paper offers a review of the scientific literature on the health and environmental impact of mercury in dentistry published over the last decade. A variety of peer-reviewed, epidemiological and large-scale clinical studies on dental amalgam, as well as published reports of professional and governmental bodies, were organised thematically and analysed. The most relevant findings of the aforementioned literature are reported. No reliance has been placed on unpublished work or publicly available opinions that are not scientifically based. In order to offer an appropriate view on the topic the toxicology, health impacts and possible environmental threats are briefly presented in relation to the relevant literature published in the last ten years. It is almost unanimously accepted that dental amalgam is a safe material, with little or insignificant adverse effect on general health. However, current and mostly unfounded environmental concerns may result in the implementation of new across the board legislation that could lead to a global dental amalgam "phase out".

  15. Crevice corrosion products of dental amalgam

    SciTech Connect

    Sutow, E.J.; Jones, D.W.; Hall, G.C.; Owen, C.G. )

    1991-07-01

    The objective of this study was to determine the in vitro corrosion products that resulted from crevice corrosion of low- and high-copper dental amalgams. Specimens were potentiostatically polarized in a chloride-containing electrolyte while set against a PTFE surface to form a crevice. After 16 h, corrosion products were examined by light microscopy, SEM, EDS, and XRD. Analysis showed the presence of three previously reported products (Sn4(OH)6Cl2, SnO, and Cu2O) and a new product, CuCl, which formed on high-copper, {gamma} 2-free amalgams. Thermodynamic considerations show that CuCl is stable for the reported in vivo potentials of amalgam restorations and the high acidity and high chloride ion concentration associated with crevice corrosion.

  16. Mercury exposure and risks from dental amalgam in the US population, post-2000.

    PubMed

    Richardson, G M; Wilson, R; Allard, D; Purtill, C; Douma, S; Gravière, J

    2011-09-15

    Dental amalgam is 50% metallic mercury (Hg) by weight and Hg vapour continuously evolves from in-place dental amalgam, causing increased Hg content with increasing amalgam load in urine, faeces, exhaled breath, saliva, blood, and various organs and tissues including the kidney, pituitary gland, liver, and brain. The Hg content also increases with maternal amalgam load in amniotic fluid, placenta, cord blood, meconium, various foetal tissues including liver, kidney and brain, in colostrum and breast milk. Based on 2001 to 2004 population statistics, 181.1 million Americans carry a grand total of 1.46 billion restored teeth. Children as young as 26 months were recorded as having restored teeth. Past dental practice and recently available data indicate that the majority of these restorations are composed of dental amalgam. Employing recent US population-based statistics on body weight and the frequency of dentally restored tooth surfaces, and recent research on the incremental increase in urinary Hg concentration per amalgam-filled tooth surface, estimates of Hg exposure from amalgam fillings were determined for 5 age groups of the US population. Three specific exposure scenarios were considered, each scenario incrementally reducing the number of tooth surfaces assumed to be restored with amalgam. Based on the least conservative of the scenarios evaluated, it was estimated that some 67.2 million Americans would exceed the Hg dose associated with the reference exposure level (REL) of 0.3 μg/m(3) established by the US Environmental Protection Agency; and 122.3 million Americans would exceed the dose associated with the REL of 0.03 μg/m(3) established by the California Environmental Protection Agency. Exposure estimates are consistent with previous estimates presented by Health Canada in 1995, and amount to 0.2 to 0.4 μg/day per amalgam-filled tooth surface, or 0.5 to 1 μg/day/amalgam-filled tooth, depending on age and other factors.

  17. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification....

  18. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification....

  19. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification....

  20. 21 CFR 872.3110 - Dental amalgam capsule.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification....

  1. Health Complaints Attributed to Dental Amalgam: A Retrospective Survey Exploring Perceived Health Changes Related to Amalgam Removal

    PubMed Central

    Kristoffersen, Agnete Egilsdatter; Alræk, Terje; Stub, Trine; Hamre, Harald Johan; Björkman, Lars; Musial, Frauke

    2016-01-01

    Background: Many patients have complex health complaints they attribute to dental amalgam. There is some evidence of symptom relief after removal of amalgam. Objective: The aims of this study were to assess the total symptom load in patients with all their amalgam fillings removed, and to investigate the self-reported improvement of health with regard to precautions taken under amalgam removal and time since removal. Methods: The survey was distributed to all members (n=999) of the Norwegian Dental patients association in 2011. The study participants returned the questionnaires anonymously by means of a pre-stamped envelope. The questionnaire asked for sociodemographic data, subjectively perceived health status, complaints persisting after amalgam removal and self-reported changes in symptoms after amalgam removal. Results: A total of 324 participants were included in the study. The majority of the participants reported improved health after amalgam removal, even though the mean degree of severity of complaints was still high. Exhaustion and musculoskeletal complaints were most severe, and reflects the fact that 38% of the participants reported poor to very poor current health. With regard to amalgam removal, associations between improved health, number of precautions applied, and time since removal were found. Conclusion: Most of the participants in this study reported improvement of health after amalgam removal even though they still suffered a high complaint load. Since absolute symptom load is a robust predictor for general health outcome and socioeconomic burden for society, a possible intervention, which enables patients to further improve their health status is desirable. PMID:28217190

  2. Patients' experiences of changes in health complaints before, during, and after removal of dental amalgam.

    PubMed

    Sjursen, Therese T; Binder, Per-Einar; Lygre, Gunvor B; Helland, Vigdis; Dalen, Knut; Björkman, Lars

    2015-01-01

    In this article, we explore how patients with health complaints attributed to dental amalgam experienced and gave meaning to changes in health complaints before, during, and after removal of all amalgam fillings. We conducted semistructured qualitative interviews with 12 participants from the treatment group in a Norwegian amalgam removal trial. Interviews took place within a couple months of the final follow-up 5 years after amalgam removal. Using the NVivo9 software, we conducted an explorative and reflective thematic analysis and identified the following themes: Something is not working: betrayed by the body, You are out there on your own, Not being sure of the importance of amalgam removal, The relief experienced after amalgam removal, and To accept, to give up, or to continue the search. We discuss the findings in the context of patients' assigning meaning to illness experiences.

  3. Patients’ experiences of changes in health complaints before, during, and after removal of dental amalgam

    PubMed Central

    Sjursen, Therese T.; Binder, Per-Einar; Lygre, Gunvor B.; Helland, Vigdis; Dalen, Knut; Björkman, Lars

    2015-01-01

    In this article, we explore how patients with health complaints attributed to dental amalgam experienced and gave meaning to changes in health complaints before, during, and after removal of all amalgam fillings. We conducted semistructured qualitative interviews with 12 participants from the treatment group in a Norwegian amalgam removal trial. Interviews took place within a couple months of the final follow-up 5 years after amalgam removal. Using the NVivo9 software, we conducted an explorative and reflective thematic analysis and identified the following themes: Something is not working: betrayed by the body, You are out there on your own, Not being sure of the importance of amalgam removal, The relief experienced after amalgam removal, and To accept, to give up, or to continue the search. We discuss the findings in the context of patients’ assigning meaning to illness experiences. PMID:26112454

  4. Electrical activity in dental amalgam of submerged divers during welding.

    PubMed

    Ortendahl, T W; Holland, R I

    1987-10-01

    Divers performing underwater manual metal arc welding/cutting (UMMA) have complained about a metallic taste phenomenon. In several dives with voluntary leakage in their diving suits, potential alterations in dental amalgam were registered when they performed UMMA. Polarization resistance values were obtained for the test amalgam cylinders used and the diver's dental restorations. These values, along with the recorded potential values of the amalgam test cylinders and of the diver's dental restorations, enabled us to calculate the depolarizing current, using the law of Ohm. The current depolarizing the amalgam test cylinder did not differ significantly from the mean intermetallic currents between the dental restorations. The clinical effect of intraoral currents when performing UMMA welding should be regarded as small, whereas considerably higher currents should not be ruled out in an intense cutting situation.

  5. The dental amalgam toxicity fear: a myth or actuality.

    PubMed

    Rathore, Monika; Singh, Archana; Pant, Vandana A

    2012-05-01

    Amalgam has been used in dentistry since about 150 years and is still being used due to its low cost, ease of application, strength, durability, and bacteriostatic effect. When aesthetics is not a concern it can be used in individuals of all ages, in stress bearing areas, foundation for cast-metal and ceramic restorations and poor oral hygiene conditions. Besides all, it has other advantages like if placed under ideal conditions, it is more durable and long lasting and least technique sensitive of all restorative materials, but, concern has been raised that amalgam causes mercury toxicity. Mercury is found in the earth's crust and is ubiquitous in the environment, so even without amalgam restorations everyone is exposed to small but measurable amount of mercury in blood and urine. Dental amalgam restorations may raise these levels slightly, but this has no practical or clinical significance. The main exposure to mercury from dental amalgam occurs during placement or removal of restoration in the tooth. Once the reaction is complete less amount of mercury is released, and that is far below the current health standard. Though amalgam is capable of producing delayed hypersensitivity reactions in some individuals, if the recommended mercury hygiene procedures are followed the risks of adverse health effects could be minimized. For this review the electronic databases and PubMed were used as data sources and have been evaluated to produce the facts regarding amalgam's safety and toxicity.

  6. The Dental Amalgam Toxicity Fear: A Myth or Actuality

    PubMed Central

    Rathore, Monika; Singh, Archana; Pant, Vandana A.

    2012-01-01

    Amalgam has been used in dentistry since about 150 years and is still being used due to its low cost, ease of application, strength, durability, and bacteriostatic effect. When aesthetics is not a concern it can be used in individuals of all ages, in stress bearing areas, foundation for cast-metal and ceramic restorations and poor oral hygiene conditions. Besides all, it has other advantages like if placed under ideal conditions, it is more durable and long lasting and least technique sensitive of all restorative materials, but, concern has been raised that amalgam causes mercury toxicity. Mercury is found in the earth's crust and is ubiquitous in the environment, so even without amalgam restorations everyone is exposed to small but measurable amount of mercury in blood and urine. Dental amalgam restorations may raise these levels slightly, but this has no practical or clinical significance. The main exposure to mercury from dental amalgam occurs during placement or removal of restoration in the tooth. Once the reaction is complete less amount of mercury is released, and that is far below the current health standard. Though amalgam is capable of producing delayed hypersensitivity reactions in some individuals, if the recommended mercury hygiene procedures are followed the risks of adverse health effects could be minimized. For this review the electronic databases and PubMed were used as data sources and have been evaluated to produce the facts regarding amalgam's safety and toxicity. PMID:22778502

  7. [The developmental history of the dental filling materials].

    PubMed

    Gong, Yi

    2008-10-01

    Caries may cause substantial defects in the hard tissue of teeth. The dental filling for defects is an effective method to resume teeth complete form and masticatory function as well as aesthetic effects. The filling material is artificial restorative material to fill the dental defects. Tracing back the developing process of dental filling materials, we can see the advancement of stomotology of human beings. There was a revolutionary change in the filling materials from filling dental cavity with Chinese medicinal herbs to silver paste, from establishing the composition and proportion standardization of the silver amalgam filling materials to the application of new macromolecule compound resin. This is a continuous improvement and renewal in the idea and technology of dental filling treatment so that perfects the dental filling method and enables the retention of more healthy dental tissue. In addition, it pushes the development of dental aesthetics, adhesives and technology. With the improvement of people's health standard, aesthetic demands and environmental awareness, compound resin restorative materials has become clinically preferred dental filling materials of doctors and patients in clinic.

  8. Significant mercury deposits in internal organs following the removal of dental amalgam, & development of pre-cancer on the gingiva and the sides of the tongue and their represented organs as a result of inadvertent exposure to strong curing light (used to solidify synthetic dental filling material) & effective treatment: a clinical case report, along with organ representation areas for each tooth.

    PubMed

    Omura, Y; Shimotsuura, Y; Fukuoka, A; Fukuoka, H; Nomoto, T

    1996-01-01

    Because of the reduced effectiveness of antibiotics against bacteria (e.g. Chlamydia trachomatis, alpha-Streptococcus, Borrelia burgdorferi, etc.) and viruses (e.g. Herpes Family Viruses) in the presence of mercury, as well as the fact that the 1st author has found that mercury exists in cancer and pre-cancer cell nuclei, the presence of dental amalgam (which contains about 50% mercury) in the human mouth is considered to be a potential hazard for the individual's health. In order to solve this problem, 3 amalgam fillings were removed from the teeth of the subject of this case study. In order to fill the newly created empty spaces in the teeth where the amalgams had formerly existed, a synthetic dental-filling substance was introduced and to solidify the synthetic substance, curing light (wavelength range reportedly between 400-520 nm) was radiated onto the substance in order to accelerate the solidifying process by photo-polymerization. In spite of considerable care not to inhale mercury vapor or swallow minute particles of dental amalgam during the process of removing it by drilling, mercury entered the body of the subject. Precautions such as the use of a rubber dam and strong air suction, as well as frequent water suctioning and washing of the mouth were insufficient. Significant deposits of mercury, previously non-existent, were found in the lungs, kidneys, endocrine organs, liver, and heart with abnormal low-voltage ECGs (similar to those recorded 1-3 weeks after i.v. injection of radioisotope Thallium-201 for Cardiac SPECT) in all the limb leads and V1 (but almost normal ECGs in the precordial leads V2-V6) the day after the procedures were performed. Enhanced mercury evaporation by increased temperature and microscopic amalgam particles created by drilling may have contributed to mercury entering the lungs and G.I. system and then the blood circulation, creating abnormal deposits of mercury in the organs named above. Such mercury contamination may then

  9. Is dental amalgam safe for humans? The opinion of the scientific committee of the European Commission

    PubMed Central

    2011-01-01

    It was claimed by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR)) in a report to the EU-Commission that "....no risks of adverse systemic effects exist and the current use of dental amalgam does not pose a risk of systemic disease..." [1, available from: http://ec.europa.eu/health/ph_risk/committees/04_scenihr/docs/scenihr_o_016.pdf]. SCENIHR disregarded the toxicology of mercury and did not include most important scientific studies in their review. But the real scientific data show that: (a) Dental amalgam is by far the main source of human total mercury body burden. This is proven by autopsy studies which found 2-12 times more mercury in body tissues of individuals with dental amalgam. Autopsy studies are the most valuable and most important studies for examining the amalgam-caused mercury body burden. (b) These autopsy studies have shown consistently that many individuals with amalgam have toxic levels of mercury in their brains or kidneys. (c) There is no correlation between mercury levels in blood or urine, and the levels in body tissues or the severity of clinical symptoms. SCENIHR only relied on levels in urine or blood. (d) The half-life of mercury in the brain can last from several years to decades, thus mercury accumulates over time of amalgam exposure in body tissues to toxic levels. However, SCENIHR state that the half-life of mercury in the body is only "20-90 days". (e) Mercury vapor is about ten times more toxic than lead on human neurons and with synergistic toxicity to other metals. (f) Most studies cited by SCENIHR which conclude that amalgam fillings are safe have severe methodical flaws. PMID:21232090

  10. Mercury in dental amalgam: Are our health care workers at risk?

    PubMed

    Sahani, M; Sulaiman, N S; Tan, B S; Yahya, N A; Anual, Z F; Mahiyuddin, W R Wan; Khan, M F; Muttalib, K A

    2016-11-01

    Dental amalgam in fillings exposes workers to mercury. The exposure to mercury was investigated among 1871 dental health care workers. The aim of the study was to evaluate the risk of mercury exposure among dental compared to nondental health care workers and to determine other risk factors for mercury exposure. Respondents answered questionnaires to obtain demographic, personal, professional, and workplace information and were examined for their own amalgam fillings. Chronic mercury exposure was assessed through urinary mercury levels. In total, 1409 dental and 462 nondental health care workers participated in the study. Median urine mercury levels for dental and nondental health care workers were 2.75 μg/L (interquartile range [IQR] = 3.0175) and 2.66 μg/L (IQR = 3.04) respectively. For mercury exposure, there were no significant risk factor found among the workers involved within the dental care. The Mann-Whitney test showed that urine mercury levels were significantly different between respondents who eat seafood more than 5 times per week compared to those who eat it less frequently or not at all (p = 0.003). The urinary mercury levels indicated significant difference between dental workers in their practice using squeeze cloths (Mann-Whitney test, p = 0.03). Multiple logistic regression showed that only the usage of cosmetic products that might contain mercury was found to be significantly associated with the urinary mercury levels (odds ratio [OR] = 15.237; CI: 3.612-64.276). Therefore, mean urinary mercury levels of health care workers were low. Exposure to dental amalgam is not associated with high mercury exposure. However, usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.

  11. [Antibacterial properties of two conventional and two high copper dental amalgams].

    PubMed

    Günyakti, N; Misirligil, A; Gökay, O

    1989-05-01

    Two conventional and two high copper dental amalgams (Non gamma 2) has been investigated for their antibacterial properties. The high copper dental amalgam, Ana 2000 possessed a very small range of antibacterial propertie against Lac. acidophilus and Staph. epidermidis, while other amalgams found to have no antibacterial activity against the ten tested microorganism strains.

  12. Early failure of Class II resin composite versus Class II amalgam restorations placed by dental students.

    PubMed

    Overton, J D; Sullivan, Diane J

    2012-03-01

    Using the information from remake request slips in a dental school's predoctoral clinic, we examined the short-term survival of Class II resin composite restorations versus Class II dental amalgam restorations. In the student clinic, resin composite is used in approximately 58 percent of Class II restorations placed, and dental amalgam is used in the remaining 42 percent. In the period examined, Class II resin composite restorations were ten times more likely to be replaced at no cost to the patient than Class II dental amalgam restorations. A total of eighty-four resin composite restorations and six amalgam restorations were replaced due to an identified failure.

  13. Whole-body imaging of the distribution of mercury released from dental fillings into monkey tissues

    SciTech Connect

    Hahn, L.J.; Kloiber, R.; Leininger, R.W.; Vimy, M.J.; Lorscheider, F.L. )

    1990-11-01

    The fate of mercury (Hg) released from dental silver amalgam tooth fillings into human mouth air is uncertain. A previous report about sheep revealed uptake routes and distribution of amalgam Hg among body tissues. The present investigation demonstrates the bodily distribution of amalgam Hg in a monkey whose dentition, diet, feeding regimen, and chewing pattern closely resemble those of humans. When amalgam fillings, which normally contain 50% Hg, are made with a tracer of radioactive {sup 203}Hg and then placed into monkey teeth, the isotope appears in high concentration in various organs and tissues within 4 wk. Whole-body images of the monkey revealed that the highest levels of Hg were located in the kidney, gastrointestinal tract, and jaw. The dental profession's advocacy of silver amalgam as a stable tooth restorative material is not supported by these findings.

  14. Dental composites and amalgam and physical development in children.

    PubMed

    Maserejian, N N; Hauser, R; Tavares, M; Trachtenberg, F L; Shrader, P; McKinlay, S

    2012-11-01

    Resin-based composite dental restoration materials may release bisphenol-A, an endocrine-disrupting chemical. Using secondary analysis of a randomized clinical safety trial of amalgam vs. composites, we tested the hypothesis that dental restoration materials affect children's growth. Children (N = 218 boys, N = 256 girls) aged 6 to 10 yrs at baseline with ≥ 2 decayed posterior teeth were randomized to amalgam or composites (bisphenol-A-diglycidyl-dimethacrylate composite for permanent teeth, urethane-dimethacrylate compomer for primary teeth) for treatment of posterior caries throughout follow-up. Primary outcomes for this analysis were 5-year changes in BMI-for-age z-scores, body fat percentage (BF%), and height velocity; exploratory analyses (n = 113) examined age at menarche. Results showed no significant differences between treatment assignment and changes in physical development in boys [(composites vs. amalgam) BF%, 4.9 vs. 5.7, p = 0.49; (BMI-z-score) 0.13 vs. 0.25, p = 0.36] or girls (8.8 vs. 7.7, p = 0.95; 0.36 vs. 0.21, p = 0.49). Children with more treatment on primary teeth had greater increases in BF% regardless of material type. Girls assigned to composites had lower risk of menarche during follow-up (hazard ratio = 0.57, 95% CI 0.35-0.95). Overall, there were no significant differences in physical development over 5 years in children treated with composites or amalgam. Additional studies examining these restoration materials in relation to age at menarche are warranted (clinicaltrials.gov number NCT00065988).

  15. The Minamata Convention on Mercury: attempting to address the global controversy of dental amalgam use and mercury waste disposal.

    PubMed

    Mackey, Tim K; Contreras, John T; Liang, Bryan A

    2014-02-15

    In October 2013, a new international binding treaty instrument called the Minamata Convention on Mercury opened for signature in Minamata City, Japan, the site of arguably the worst public health and environmental disaster involving mercury contamination. The treaty aims to curb the significant health and environmental impacts of mercury pollution and includes provisions addressing the mining, export and import, storage, and waste management of products containing mercury. Importantly, a provision heavily negotiated in the treaty addresses the use of dental fillings using mercury amalgam, an issue that has been subject to decades of global controversy. Though use of dental amalgam is widespread and has benefits, concerns have been raised regarding the potential for human health risk and environmental damage from emissions and improper waste management. While the Minamata Convention attempts to address these issues by calling for a voluntary phase-down of dental amalgam use and commitment to other measures, it falls short by failing to require binding and measurable targets to achieve these goals. In response, the international community should begin exploring ways to strengthen the implementation of the dental amalgam treaty provisions by establishing binding phase-down targets and milestones as well as exploring financing mechanisms to support treaty measures. Through strengthening of the Convention, stakeholders can ensure equitable access to global oral health treatment while also promoting responsible environmental stewardship.

  16. Speciation of mercury excreted in feces from individuals with amalgam fillings.

    PubMed

    Engqvist, A; Colmsjö, A; Skare, I

    1998-01-01

    Investigators established methods for the analysis of total mercury (Hg-total), oxidized mercury and mercury bound to sulfhydryl groups (Hg-S), mercury vapor (Hg0), and mercury from amalgam particles (APs) in fecal samples. Two individuals consumed mercury as a mercury-cysteine complex mercury vapor, and mercury from amalgam particles, and the cumulative excretion of mercury in feces was followed. Investigators found that 80% of the mercury from amalgam particles and mercury bound to sulfhydryl groups was excreted, but only 40% of the mercury vapor was excreted. Speciation of mercury excreted in feces from 6 individuals with a moderate loading of amalgam fillings showed that most of the mercury originating from the fillings consisted of oxidized mercury, which was probably bound to sulfhydryl-containing compounds. The proportion of amalgam particles in fecal samples from these individuals was low, and it did not exceed 26% of the total amount of mercury excreted.

  17. Dental fillings in Civil War skulls: what do they tell us?

    PubMed

    Glenner, R A; Willey, P; Sledzik, P S; Junger, E P

    1996-11-01

    This article discusses the dental techniques, methods and materials used in the South during the Civil War based on the dental restorations found in the skulls of four confederate soldiers. The skulls display a variety of dental filling materials, including thorium, lead, tin and tin amalgam. These materials were used at a time when more valuable materials, such as gold and silver, were not readily available in the South.

  18. Amalgam

    SciTech Connect

    Fox, Kevin

    2012-09-05

    Amalgam is a system that allows you to generate collections of files that work with conventional tools but take up minimal extra space on storage. If you already are archiving files in a file system and don't want to make multiple copies of whole files in order to ship the data somewhere then this system is for you. Amalgam consists of tools that allow you to create and get information about '.amalgam' files which contain just the metadata associated with a set of files. It also contains a fuse file system that, using amalgam files, will dynamically create traditional tar files. With this setup, you can see multiple orders of magnitude reduction in storage requirements for temporary data collections.

  19. [Abrasion measurements in vivo in occlusal composite and amalgam fillings].

    PubMed

    Meier, C; Lutz, F

    1978-09-01

    A new method for quantitative measurement of occlusal wear on restorations is described. In a clinical evaluation with four different composites and an amalgam the method proved to be simple in execution and very exact. Statistical analysis after 7 months has shown significant differences in wear resistance of the different materials. The nature of the resulting wear was electron optically examined. Typical structural surface characteristics were observed for each of the different materials. More recently developed composities utilizing extremly small filler particles (Aerosil) seem to be comparable to amalgam in wear resistance.

  20. Prenatal Exposure to Dental Amalgam: Evidence from the Seychelles Child Development Main Cohort

    PubMed Central

    Watson, Gene E.; Lynch, Miranda; Myers, Gary J.; Shamlaye, Conrad F.; Thurston, Sally W.; Zareba, Grazyna; Clarkson, Thomas W.; Davidson, Philip W.

    2011-01-01

    Background Dental amalgams contain approximately 50% metallic mercury and emit small quantities of mercury vapor. Controversy surrounds whether fetal exposure to mercury vapor from maternal dental amalgams has neurodevelopmental consequences. Methods Maternal amalgam status during gestation (prenatal mercury vapor exposure) was determined retrospectively on 587 mother-child pairs enrolled in a prospective longitudinal cohort study of effects of prenatal and recent postnatal methylmercury exposure on neurodevelopment. Covariate-adjusted associations were examined between 6 age-appropriate neurodevelopmental tests administered at 66 months of age and prenatal maternal amalgam status. Models were fit without and with adjustment for prenatal and recent postnatal methylmercury exposure metrics. Results Mean maternal amalgams present during gestation were 5.1 surfaces (range 1-22) in the 42% of mothers with amalgams. No significant adverse associations were found between the number of prenatal amalgam surfaces and any of the 6 outcomes, with or without adjustment for prenatal and postnatal methylmercury exposure. Analyses using our secondary metric, prenatal amalgam occlusal point scores, showed an adverse association in males only on the Letter Word Recognition subtest of the Woodcock-Johnson Tests of Achievement, and several apparently beneficial associations for females only. Conclusions This study provides no support for the hypothesis that prenatal mercury vapor exposure from maternal dental amalgams results in neurobehavioral consequences in the child. These findings need confirmation from a prospective study of co-exposure to methyl mercury and mercury vapor. PMID:22041415

  1. Effects of magnetic fields from underwater electrical cutting on in vitro corrosion of dental amalgam

    SciTech Connect

    Ortendahl, T.W.; Hoegstedt, P.O.; Odelius, H.; Noren, J.G.

    1988-11-01

    Metallic taste has been reported from divers working with underwater electric welding and cutting. An in vitro model was designed to simulate the intraoral situation of the divers with respect to the magnetic field. Potentiostatic analyses were performed on amalgam samples exposed to AC and DC magnetic fields. Morphologic changes were analyzed using differential interference light microscopy and scanning electron microscopy. Chemical changes on the surface of the amalgam samples were analyzed with secondary ion mass spectrometry. Results demonstrated that dental amalgams exposed to a specific AC magnetic field underwent morphologic and chemical changes in the superficial amalgam layers.

  2. Effects of magnetic fields from underwater electrical cutting on in vitro corrosion of dental amalgam.

    PubMed

    Ortendahl, T W; Högstedt, P; Odelius, H; Norén, J G

    1988-11-01

    Metallic taste has been reported from divers working with underwater electric welding and cutting. An in vitro model was designed to simulate the intraoral situation of the divers with respect to the magnetic field. Potentiostatic analyses were performed on amalgam samples exposed to AC and DC magnetic fields. Morphologic changes were analyzed using differential interference light microscopy and scanning electron microscopy. Chemical changes on the surface of the amalgam samples were analyzed with secondary ion mass spectrometry. Results demonstrated that dental amalgams exposed to a specific AC magnetic field underwent morphologic and chemical changes in the superficial amalgam layers.

  3. New science challenges old notion that mercury dental amalgam is safe.

    PubMed

    Homme, Kristin G; Kern, Janet K; Haley, Boyd E; Geier, David A; King, Paul G; Sykes, Lisa K; Geier, Mark R

    2014-02-01

    Mercury dental amalgam has a long history of ostensibly safe use despite its continuous release of mercury vapor. Two key studies known as the Children's Amalgam Trials are widely cited as evidence of safety. However, four recent reanalyses of one of these trials now suggest harm, particularly to boys with common genetic variants. These and other studies suggest that susceptibility to mercury toxicity differs among individuals based on multiple genes, not all of which have been identified. These studies further suggest that the levels of exposure to mercury vapor from dental amalgams may be unsafe for certain subpopulations. Moreover, a simple comparison of typical exposures versus regulatory safety standards suggests that many people receive unsafe exposures. Chronic mercury toxicity is especially insidious because symptoms are variable and nonspecific, diagnostic tests are often misunderstood, and treatments are speculative at best. Throughout the world, efforts are underway to phase down or eliminate the use of mercury dental amalgam.

  4. Increased mercury release from dental amalgam restorations after exposure to electromagnetic fields as a potential hazard for hypersensitive people and pregnant women.

    PubMed

    Mortazavi, Ghazal; Mortazavi, S M J

    2015-01-01

    Over the past decades, the use of common sources of electromagnetic fields such as Wi-Fi routers and mobile phones has been increased enormously all over the world. There is ongoing concern that exposure to electromagnetic fields can lead to adverse health effects. It has recently been shown that even low doses of mercury are capable of causing toxicity. Therefore, efforts are initiated to phase down or eliminate the use of mercury amalgam in dental restorations. Increased release of mercury from dental amalgam restorations after exposure to electromagnetic fields such as those generated by MRI and mobile phones has been reported by our team and other researchers. We have recently shown that some of the papers which reported no increased release of mercury after MRI, may have some methodological errors. Although it was previously believed that the amount of mercury released from dental amalgam cannot be hazardous, new findings indicate that mercury, even at low doses, may cause toxicity. Based on recent epidemiological findings, it can be claimed that the safety of mercury released from dental amalgam fillings is questionable. Therefore, as some individuals tend to be hypersensitive to the toxic effects of mercury, regulatory authorities should re-assess the safety of exposure to electromagnetic fields in individuals with amalgam restorations. On the other hand, we have reported that increased mercury release after exposure to electromagnetic fields may be risky for the pregnant women. It is worth mentioning that as a strong positive correlation between maternal and cord blood mercury levels has been found in some studies, our findings regarding the effect of exposure to electromagnetic fields on the release of mercury from dental amalgam fillings lead us to this conclusion that pregnant women with dental amalgam fillings should limit their exposure to electromagnetic fields to prevent toxic effects of mercury in their fetuses. Based on these findings, as infants

  5. In-situ measurements of low-level mercury vapor exposure from dental amalgam with zeeman atomic absorption spectroscopy.

    PubMed

    Halbach, Stefan; Welzl, Gerhard

    2004-01-01

    Alongside food, emissions from amalgam fillings are an essential contribution to man's mercury burden. Previous methods for the determination of intraoral mercury vapor (Hg degrees ) release used principally some form of preconcentration of Hg on gold (film or wool), allowing relatively few measurements with unknown precision and sensitivity at selected times. Recently available computer-controlled Hg detectors operating on Zeeman atomic absorption spectroscopy (ZAAS) facilitate the direct real-time measurement of Hg degrees concentrations. It was the aim to adapt this method for a comparative investigation of emission processes from fillings in situ and from amalgam specimens in vitro. In addition to the ZAAS instrument, the apparatus consisted of a pump, magnetic valves, an electronic flow controller and a handle with a disposable mouth piece for aspiration of oral air. A programmable timer integrated the computer-controlled instrument operation and the data collection into a standard sampling protocol. A fast exponential decay of the emission was found after stimulation of amalgam specimens and of fillings in situ (halftimes 8.6 and 10.7 min). Precision was evaluated by a series of measurements on a single patient which indicated a consistently low coefficient of variation between 18% and 25%. After insertion of a few new fillings, sensitivity was high enough to detect a significant increase in emission against the background emission from the majority of old fillings. Zeeman-AAS in connection with a semi-automated sampling protocol and data storage provides precise in-situ measurements of Hg degrees emission from dental amalgam with real-time resolution. This facilitates the detailed exploration of the Hg degrees release kinetics and the applicability to large-scale studies.

  6. Amalgam and composite posterior restorations: curriculum versus practice in operative dentistry at a US dental school.

    PubMed

    Ottenga, Marc E; Mjör, Ivar

    2007-01-01

    This study recorded the number of preclinical lecture and simulation laboratory sessions spent teaching the preparation and placement of amalgam and resin composite posterior restorations. These data were compared to the use of both materials in the operative clinic as placed by third- and fourth-year students. The number of posterior restorations inserted by the students, expressed as a function of the number of restoration surfaces, was also evaluated. The results show that the teaching of posterior restorations pre-clinically has consistently favored amalgam 2.5 to 1 during the last three years. However, clinically, resin composite is being used for posterior restorations 2.3 times more often than amalgam. The only instance that favored amalgam over composite during the last year was in the placement of four surface posterior restorations. This shift in emphasis from amalgam to composite needs to be addressed within dental educational institutions so that newly graduated dentists are prepared to place composite restorations properly.

  7. The Chemistry of Modern Dental Filling Materials.

    ERIC Educational Resources Information Center

    Nicholson, John W.; Anstice, H. Mary

    1999-01-01

    Discusses materials used by dentists to restore teeth after decay has been removed. Shows how dental-material science is an interdisciplinary field in which chemistry plays a major part. Reviews the many developments polymer chemistry has contributed to the field of dental fillings. (CCM)

  8. Viscoelastic Behavior of High-Copper Dental Amalgam Alloys,

    DTIC Science & Technology

    1980-07-24

    Apprv.-. . - 17. DISTRIWUTION STATEMENT (of the abstract entered in Block 20, If dliffern Item Roiport) • . y-",.-,D T IC 13. SUPPLEMENTARY NOTES...MAUG 1 3 1980 A * 19. KEY WORDS (Continue on recerse aide if necea2wry and Identify by block number) ? i Amalgam alloys; high-copper amalgam alloys...viscoelastic properties andstress relaxation. C 2 LJJ 20. ABSTRACT (Con"nue on reverse side , f #ncoary and Identify by block numbe) Stress relaxation of

  9. Rapid communication: acute exposure to mercury from dental amalgam does not affect the levels of C-reactive protein or interleukin-6 in peripheral blood.

    PubMed

    Sandborgh-Englund, Gunilla; af Geijersstam, Eric; Loftenius, Annika

    2003-03-28

    In a previous study, a significant increase in serum interleukin-6 (IL-6) was apparent after an acute low-level mercury (Hg) exposure, achieved by removal of amalgam fillings (Loftenius et al., 1998). In the present study, 11 healthy volunteers were exposed to an oral dose of 1 g of pulverized amalgam powder. Hg, IL-6, and C-reactive protein (CRP) levels in plasma were followed before and up to 72 h after exposure. The Hg levels were low and stable prior to exposure and increased rapidly after exposure. The median Hg increase was 12.9 nmol/L, which is considerably higher than in the previous study. No significant change over time was observed for IL-6 and CRP levels. Therefore, it cannot be ruled out that our previous finding of increasing IL-6 levels detected after acute low-level Hg exposure through removal of amalgam fillings was due to the dental treatment per se.

  10. Monte Carlo dose calculation in dental amalgam phantom.

    PubMed

    Aziz, Mohd Zahri Abdul; Yusoff, A L; Osman, N D; Abdullah, R; Rabaie, N A; Salikin, M S

    2015-01-01

    It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.

  11. Steady-state transfer and depletion kinetics of mercury from amalgam fillings.

    PubMed

    Halbach, S; Welzl, G; Kremers, L; Willruth, H; Mehl, A; Wack, F X; Hickel, R; Greim, H

    2000-10-02

    In 29 volunteers with a low amalgam load, the number of amalgam-covered tooth surfaces and the occlusal area of the fillings were determined. Before and at select times after removal of all amalgams, concentrations of total mercury were measured by cold-vapor atomic absorption in plasma and erythrocytes as well as in urine together with the excretion rate. Absorbed daily doses were estimated from intraoral Hg emission by two separate methods. The transfer of Hg from the fillings via the oral cavity and blood to urinary excretion was evaluated according to the most representative combination of parameters. This consisted of occlusal area (1), absorbed dose (2), Hg concentration in plasma (3) and urinary excretion (4). Pairwise correlation coefficients were 0.49 for parameters 1 vs. 2, and 0.75 each for parameters 2 vs. 3 and 3 vs. 4. Within 9 days after removal of the fillings, a transient increase in Hg levels was observed in plasma only; in the group without a rubber dam, concentrations increased significantly above pre-removal values at days 1 and 3, whereas they decreased significantly below pre-removal values at day 30 in the rubber-dam group and at day 100 in both groups. Excretion rates decreased significantly at day 100 in the protected group. Peak plasma-Hg was 0.6 ng/ml on average at day 1 and decreased with halftimes of 3 and 43 days in subjects protected by a rubber dam. The results indicated that concentrations of total mercury in plasma responded rapidly to changes in the amalgam status and reflected the actual absorption most reliably. Notably, plasma-Hg levels were sensitive enough to detect a transient attenuation of the additional exposure after using a rubber dam during the removal of only a few fillings. However, being small in magnitude and lasting 100 days at best, the rubber-dam effect had minor toxicological relevance.

  12. Is it the end of the road for dental amalgam? A critical review

    PubMed Central

    Shenoy, Arvind

    2008-01-01

    The longevity of dental restorations is dependent on many factors, including those related to materials, the dentist, and the patient. Dental amalgams have successfully served the profession for over a century. The main reasons for restoration failure are secondary caries, fracture of the bulk of the restoration or of the tooth, and marginal deficiencies and wear. The importance of direct-placement, aesthetic, tooth-colored restorative materials is still increasing. Amalgam restorations are being replaced because of alleged adverse health effects and inferior aesthetic appearance. All alternative restorative materials and procedures, however, have certain limitations. This article will attempt to critically analyse both amalgams and resin based composites, through an evaluation of scientific literature. PMID:20142895

  13. Biomarkers of kidney integrity in children and adolescents with dental amalgam mercury exposure: Findings from the Casa Pia children's amalgam trial

    SciTech Connect

    Woods, James S. Martin, Michael D.; Leroux, Brian G.; DeRouen, Timothy A.; Bernardo, Mario F.; Luis, Henrique S.; Leitao, Jorge G.; Kushleika, John V.; Rue, Tessa C.; Korpak, Anna M.

    2008-11-15

    Mercury is toxic to the kidney, and dental amalgam is a source of mercury exposure. Few studies have evaluated the effects of dental amalgam on kidney function in a longitudinal context in children. Here, we evaluated urinary concentrations of glutathione S-transferases (GSTs) {alpha} and {pi} as biomarkers of renal proximal and distal tubular integrity, respectively, and albumin as a biomarker of glomerular integrity in children and adolescents 8-18 years of age over a 7-year course of dental amalgam treatment. Five hundred seven children, 8-12 years of age at baseline, participated in a clinical trial to evaluate the neurobehavioral and renal effects of dental amalgam in children. Subjects were randomized to either dental amalgam or resin composite treatments. Urinary GSTs {alpha} and {pi}, albumin, and creatinine concentrations were measured at baseline and annually in all subjects. Results were evaluated using linear regression analysis. GST-{alpha} concentrations were similar between treatment groups and in each sex and race (white vs. non-white) group in each follow-up year. GST-{pi} levels tended upward over the course of follow-up by four- to six-fold. This increase was seen in all groups irrespective of the treatment, race, or gender. Females had GST-{pi} levels approximately twice those of males at all ages. Albumin concentrations were constant throughout the follow-up period and did not differ by treatment, although females had 39% higher albumin levels than males. Additionally, we found no significant effects of amalgam treatment on the proportion of children with microalbuminuria (>30 mg/g creatinine). These findings are relevant within the context of children's health risk assessment as relates to the safety of mercury exposure from dental amalgam on kidney function. These data also provide normative values for sensitive indices of renal functional integrity that may serve in the evaluation of children and adolescents with renal disorders.

  14. Evidence summary: which dental liners under amalgam restorations are more effective in reducing postoperative sensitivity?

    PubMed

    Nasser, Mona

    2011-06-10

    Since August 2009, members of the Primary Care Dentistry Research Forum (www.dentistryresearch.org) have taken part in an online vote to identify questions in day-to-day practice that they felt most needed to be answered with conclusive research. The question that receives the most votes each month forms the subject of a critical appraisal of the relevant literature. Each month a new round of voting takes place to decide which further questions will be reviewed. Dental practitioners and dental care professionals are encouraged to take part in the voting and submit their own questions to be included in the vote by joining the website. The paper below details a summary of the findings of the ninth critical appraisal. In order to address the question raised by dentistry research forum, first a search was conducted for systematic reviews on the topic. There was one systematic review retrieved comparing bonded amalgam restorations versus non-bonded amalgam restorations. However, there was no other systematic review identified assessing the effectiveness of dental liners under amalgam restorations in general. Therefore, a search was conducted for any randomised controlled trial (RCT) comparing use of a lining under amalgam restorations versus no lining or RCTs comparing differing lining materials under amalgam against each other. There were eight relevant RCTs identified. Due to the low quality, small sample sizes or lack of adequate reporting of the outcome data, the evidence is inadequate to claim or refute a difference in postoperative sensitivity between different dental liners. Further well-conducted RCTs are needed to answer this question. These RCTs would be preferably included and synthesised in a systematic review.

  15. Mercury exposure in the work place and human health: dental amalgam use in dentistry at dental teaching institutions and private dental clinics in selected cities of Pakistan.

    PubMed

    Khwaja, Mahmood A; Nawaz, Sadaf; Ali, Saeed Waqar

    2016-03-01

    During the past two decades, mercury has come under increasing scrutiny with regard to its safety both in the general population and in occupationally exposed groups. It's a growing issue of global concern because of its adverse environmental and health impacts. Very few investigations on mercury amalgam use in the dentistry sector have been carried out in South Asia and there is little data reported on mercury contamination of indoor/outdoor air at dental sites. According to an earlier SDPI study, reported in 2013, alarmingly high mercury levels were observed in air (indoor as well as outdoor) at 11 of the 34 visited dental sites (17 dental teaching institutions, 7 general hospitals & 10 dental clinics) in five main cities of Pakistan. 88% of the sites indicated indoor mercury levels in air above the USA EPA reference level of 300 ng/m3. According to our study, carried out at 38 dental teaching institutions in 12 main cities (in Khyber Pakhtunkhwa, Punjab and Sindh provinces) of Pakistan, respondents were of the opinion that the currently offered BDS curriculum does not effectively guide outgoing dental professionals and does not provide them adequate knowledge and training about mercury/mercury amalgam and other mercury related human health and mercury waste issues. 90% of respondents supported the review and revision of the present dental curriculum offered at dental teaching institutions in the country, at the earliest. A study has also been conducted to assess the status of mercury amalgam use in private dental clinics in Gilgit, Hunza, Peshawar, Rawalpindi and Islamabad. More than 90 private dental clinics were visited and dental professionals/private clinics in-charge were interviewed during June-July, 2015. The focus areas of the study were Hg amalgam toxicity, its waste management practices and safety measures practiced among the dental practitioners. In the light of the findings described and discussed in this brief report, to safeguard public health and

  16. Corrosion of the eta'(Cu-Sn) phase in dental amalgam.

    PubMed

    Marek, M; Okabe, T; Butts, M B; Fairhurst, C W

    1983-11-01

    Previous studies have shown preferential corrosion of the eta'(Cu-Sn) phase in high-copper dental amalgam both in vitro and in vivo, while samples of pure eta' have shown high corrosion resistance. To clarify this contradiction, samples of pure eta' crystals mixed with other phases were prepared and tested. Evaluation of the corrosion resistance was based on the results of coulometry at constant potential and potentiodynamic polarization. The corrosion susceptibility of eta' in the matrix of gamma 1(Ag-Hg) was considerably higher than the susceptibility of isolated eta'. The susceptibility of pure eta' also could be increased by plating it will small amounts of Hg. It was concluded that in dental amalgam, the presence of mercury in the phases surrounding eta' reduces its resistance to corrosion. Although eta' is more resistant to corrosion than gamma 2(Sn-Hg) which appears in low-copper amalgams, it is the least corrosion resistant major phase in high-copper amalgams and can suffer deterioration.

  17. Effect of dental amalgam on gene expression profiles in rat cerebrum, cerebellum, liver and kidney.

    PubMed

    Takahashi, Yoshifumi; Tsuruta, Shozo; Honda, Akiko; Fujiwara, Yasuyuki; Satoh, Masahiko; Yasutake, Akira

    2012-01-01

    Dental amalgam is a source of exposure to elemental mercury vapor in the general population. The aim of this study was to elucidate the effect of elemental mercury vapor exposure from dental amalgam restorations on gene expression profiles. Out of 26,962 rat genes, mercury vapor was found to increase the expression of 1 gene (Atp1b3) and decrease the expression of 1 gene (Tap1) in the cerebrum, increase the expression of 1 gene (Dnaja2) in the cerebellum, increase the expression of 2 genes (Actb and Timm23) and decrease the expression of 1 gene (Spink3) in the liver, increase the expression of 2 genes (RT1-Bb and Mgat5) and decrease the expression of 6 genes (Tnfaip8, Rara, Slc2a4, Wdr12, Pias4 and Timm13) in the kidney.

  18. Neurodevelopmental outcomes at 5 years in children exposed prenatally to maternal dental amalgam: the Seychelles Child Development Nutrition Study.

    PubMed

    Watson, Gene E; van Wijngaarden, Edwin; Love, Tanzy M T; McSorley, Emeir M; Bonham, Maxine P; Mulhern, Maria S; Yeates, Alison J; Davidson, Philip W; Shamlaye, Conrad F; Strain, J J; Thurston, Sally W; Harrington, Donald; Zareba, Grazyna; Wallace, Julie M W; Myers, Gary J

    2013-01-01

    Limited human data are available to assess the association between prenatal mercury vapor (Hg⁰)) exposure from maternal dental amalgam restorations and neurodevelopment of children. We evaluated the association between maternal dental amalgam status during gestation and children's neurodevelopmental outcomes at 5 years in the Seychelles Child Development Nutrition Study (SCDNS). Maternal amalgam status was determined prospectively in a longitudinal cohort study examining the associations of prenatal exposure to nutrients and methylmercury (MeHg) with neurodevelopment. A total of 236 mother-child pairs initially enrolled in the SCDNS in 2001 were eligible to participate. Maternal amalgam status was measured as number of amalgam surfaces (the primary metric) and number of occlusal points. The neurodevelopmental assessment battery was comprised of age-appropriate tests of cognitive, language, and perceptual functions, and scholastic achievement. Linear regression analysis controlled for MeHg exposure, maternal fatty acid status, and other covariates relevant to child development. Maternal amalgam status evaluation yielded an average of 7.0 surfaces (range 0-28) and 11.0 occlusal points (range 0-40) during pregnancy. Neither the number of maternal amalgam surfaces nor occlusal points were associated with any outcome. Our findings do not provide evidence to support a relationship between prenatal exposure to Hg⁰ from maternal dental amalgam and neurodevelopmental outcomes in children at 5 years of age.

  19. Allergy to dental materials with special reference to the use of amalgam and polymethylmethacrylate.

    PubMed

    Kaaber, S

    1990-12-01

    The increase in new clinical materials with questionable biological properties and the corresponding increase in awareness in patients to health hazards from dental materials are two important problems of modern clinical dentistry. Based upon evidence from clinical research the hypersensitivity problems related to the use of silver amalgam and acrylic denture base materials are reviewed to define possible risk groups among dental patients. In silver amalgam therapy the main risk group is patients with contact lesions in the oral mucosa adjacent to the restorations, as this group exhibits a high frequency of skin sensitivity to mercury and other base materials in dental amalgam. Among denture wearers a corresponding risk group has been observed among patients with previous allergic diseases and burning mouth syndrome. In these cases a high incidence of skin sensitivity reactions to denture allergens has been observed, usually to methylmethacrylate monomer and formaldehyde. Some possible pathogenic mechanisms leading to a contact allergy of the oral mucosa in these patient groups are discussed.

  20. Legislation and informed consent brochures for dental patients receiving amalgam restorations.

    PubMed

    Edlich, Richard F; Cochran, Amy A; Cross, Catherine L; Wack, Courtney A; Long, William B; Newkirk, Anthony T

    2008-01-01

    In 2008, Norway banned the use of mercury for amalgam restorations. Four states in the United States have developed Informed Consent Brochures for amalgam restorations that must be given to their dental patients. The authors describe a patient who had a large cavity in his left lower molar tooth no.18 that had to be removed by an oral surgeon. When the patient went to the oral surgeon, the surgeon told the patient that he would replace the carious tooth with a gold implant. He was not given an Informed Consent Brochure regarding dental restorative materials. The oral surgeon extracted the carious tooth, replacing the tooth with a supposed gold crown implant. On his yearly dental examination, his dentist took an x-ray of his dental implant and explained that the x-ray could not distinguish whether the implant contained either gold or mercury. Consequently, the dentist referred him to a dental clinic in which the dental implant could be removed without mercury contamination of the patient's neurologic system during the extraction of the implant from the root canal. During the removal of the dental restoration, the dentist found build up expanding into the root canal that had a black color. The crown and underlying tooth were sent to ALT BioScience for analysis. Elemental analysis of the crown and underlying tooth confirmed the presence of mercury in the restoration. The patient should have been given an Informed Consent Brochure by the dentist that described the dental restoration that was used in the dental implant.

  1. Copper, zinc, and selenium in human blood and urine after injection of sodium 2,3-dimercaptopropane-1-sulfonate: a study on subjects with dental amalgam.

    PubMed

    Høl, Paul Johan; Vamnes, Jan Sverre; Gjerdet, Nils Roar; Eide, Rune; Isrenn, Rolf

    2003-01-01

    This study investigated the effects of a single dose of intravenously administered sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) on the essential elements copper, zinc, and selenium in human blood and urine. The possible role of dental amalgam was also addressed. Eighty individuals, divided in four groups according to the presence or absence of dental amalgam fillings and symptoms self-related to such fillings, were given DMPS (2 mg/kg body wt) and 500 mL Ringer's acetate intravenously. Urine and blood were collected prior to the injection, and thereafter at intervals over a 24-h period. Cu, Zn, and Se concentrations were determined by atomic absorption spectrometry methods. A statistically significant increase in the concentrations of Cu and Zn in urine was observed 30 and 120 min after the DMPS injection compared to the preinjection concentrations. The concentrations of Se were not affected. The cumulated excretion over 24 h after DMPS injection constitutes only from 0.1% to 0.7% of the body content of these elements. There was no effect of different amalgam statuses on Cu and Zn excretion. We found a temporary decrease (4-7%) in the concentrations of Cu, Zn, and Se in blood 15 and 30 min after DMPS, but this seems to be the result of dilution factors. Administration of a single dose of DMPS does not affect the body stores of the essential elements Cu, Zn, and Se.

  2. Comparison of chlorine and chloramine in the release of mercury from dental amalgam.

    PubMed

    Stone, Mark E; Scott, John W; Schultz, Stephen T; Berry, Denise L; Wilcoxon, Monte; Piwoni, Marv; Panno, Brent; Bordson, Gary

    2009-01-01

    The purpose of this project was to compare the ability of chlorine (HOCl/OCl(-)) and monochloramine (NH(2)Cl) to mobilize mercury from dental amalgam. Two types of amalgam were used in this investigation: laboratory-prepared amalgam and samples obtained from dental-unit wastewater. For disinfectant exposure simulations, 0.5 g of either the laboratory-generated or clinically obtained amalgam waste was added to 250 mL amber bottles. The amalgam samples were agitated by end-over-end rotation at 30 rpm in the presence of 1 mg/L chlorine, 10 mg/L chlorine, 1 mg/L monochloramine, 10 mg/L monochloramine, or deionized water for intervals of 0 h, 2 h, 4 h, 8 h, and 24 h for the clinically obtained amalgam waste samples and 4 h and 24 h for the laboratory-prepared samples. Chlorine and monochloramine concentrations were measured with a spectrophotometer. Samples were filtered through a 0.45 microm membrane filter and analyzed for mercury with USEPA standard method 245.7. When the two sample types were combined, the mean mercury level in the 1 mg/L chlorine group was 0.020 mg/L (n=25, SD=0.008). The 10 mg/L chlorine group had a mean mercury concentration of 0.59 mg/L (n=25, SD=1.06). The 1 mg/L chloramine group had a mean mercury level of 0.023 mg/L (n=25, SD=0.010). The 10 mg/L chloramine group had a mean mercury level of 0.024 mg/L (n=25, SD=0.011). Independent samples t-tests showed that there was a significant difference between the natural log mercury measurements of 10 mg/L chlorine compared to those of 1 mg/L and 10 mg/L chloramine. Changing from chlorine to chloramine disinfection at water treatment plants would not be expected to produce substantial increases in dissolved mercury levels in dental-unit wastewater.

  3. Influence of thermal treatments on Ag Sn Cu powders in order to reduce mercury contents in dental amalgam.

    PubMed

    Bracho-Troconis, C; Colon, P; Bartout, J D; Bienvenu, Y

    2000-01-01

    The mercury content of dental amalgams is a controversial subject with regard to the biological properties of these materials. The object of this study is to optimize the thermal treatments performed on an experimental powder in order to obtain a low mercury ratio (41% by weight) while preserving the desirable clinical qualities of the material. Using atomized powder, two types of thermal treatments are performed: A1, to obtain a partially annealed structure and A2, to obtain a complete homogenization. The kinetics of the amalgamation reaction is mainly evaluated by X-ray diffraction to identify the newly formed phases as a function of setting time. Mechanical properties are evaluated according to the ISO norms at 37 degrees C. Metallographical examination of the amalgams shows a Ag-Hg phase which acts as a matrix incorporating the Cu-Sn and Ag-Sn compounds. The setting kinetics of the A1 amalgams is linear and slightly more rapid than that of the A2 amalgam. The mechanical properties of the amalgams are significantly improved regarding the higher mercury content commercial amalgams. A specific thermal treatment permits us to slow down the diffusion of mercury between the different intermetallic compounds into the powder. The final amalgam composition, thus, most approaches the stoechiometric ratio calculated from a quaternary diagram.

  4. Dental clinics: a point pollution source, not only of mercury but also of other amalgam constituents.

    PubMed

    Shraim, Amjad; Alsuhaimi, Awadh; Al-Thakafy, Jalal Thamer

    2011-08-01

    Current literature suggests that amalgam waste from dental clinics is a point-source of mercury pollution in the environment. However, apart from mercury, other amalgam constituents (e.g. Ag, Sn, Cu, and Zn) in dental clinics' wastewater have not been reported in the literature before. The objective of this study was to evaluate the concentrations of mercury and other metals in the wastewater of some dental clinics and the influent of a wastewater treatment plant in Al-Madinah Al-Munawarah (KSA). Samples were collected over a 2-month period from three dental clinics and analyzed for metals using ICP-MS. The mean concentrations of Hg, Ag, Sn, Cu, and Zn in the samples were 5.3±11.1, 0.49±0.96, 3.0±10.7, 10.0±14.5, and 76.7±106 mg L(-1), respectively. Additionally, high concentrations of other metals such as Mg (14.4±15.2 mg L(-1)), Mn (3.0±4.6 mg L(-1)), Fe (3.0±4.5 mg L(-1)), Sr (1.6±2.4 mg L(-1)), and Ba (6.9±10.3 mg L(-1)) were also found. These values are much higher than the local permissible limits. Most of the metals of interest were also detected in the influent of the wastewater treatment plant. This renders dental clinics wastewater a hazardous waste which should be properly treated before it is discharged into the environment.

  5. Determination of mercury in blood, urine and saliva for the biological monitoring of an exposure from amalgam fillings in a group with self-reported adverse health effects.

    PubMed

    Zimmer, Holger; Ludwig, Heidi; Bader, Michael; Bailer, Josef; Eickholz, Peter; Staehle, Hans Jörg; Triebig, Gerhard

    2002-04-01

    It has been argued that the release of mercury from amalgam fillings is of toxicological relevance. The aim of the study was to determine the internal mercury exposure of two groups differing in their attitude towards possible health hazards by mercury from amalgam fillings. It was to be examined if the two groups differ with regard to the mercury concentration in different biological matrices and to compare the results with current reference values. Blood, urine and saliva samples were analyzed from 40 female subjects who claimed to suffer from serious health damage due to amalgam fillings ("amalgam sensitive subjects"). 43 female control subjects did not claim any association ("amalgam non-sensitive controls"). Mercury was determined by means of cold vapour atomic absorption spectrometry. Number and surfaces of amalgam fillings were determined by dentists for each subject. Median (range) mercury levels in blood were 2.35 (0.25-13.40) micrograms/l for "amalgam sensitive subjects" and 2.40 (0.25-10.50) micrograms/l for "amalgam non-sensitive controls". In urine, the median mercury concentrations were 1.55 (0.06-14.70) micrograms/l and 1.88 (0.20-8.43) micrograms/g creatinine respectively. No significant differences could be found between the two groups. Mercury levels in blood and urine of the examined subjects were within the range of background levels in the general population including persons with amalgam fillings. Stimulated saliva contained 76.4 (6.7-406.0) micrograms mercury/l in "amalgam sensitive subjects" and 57.0 (2.8-559.0) micrograms mercury/l in controls (not significant). Mercury levels in saliva did not correlate with the concentrations in blood and urine, but merely with the number of amalgam fillings or of the filling surfaces. Mercury in saliva is therefore not recommended for a biological monitoring.

  6. The Chemistry of Modern Dental Filling Materials

    NASA Astrophysics Data System (ADS)

    Nicholson, John W.; Anstice, H. Mary

    1999-11-01

    The chemistry underpinning modern tooth-colored dental fillings is described. Two broad groups of material are covered, the so-called composite resins and the glass-ionomer cements. Composite resins consist of bulky difunctional monomers together with high loadings of powdered inorganic fillers, and they set by addition polymerization. Glass-ionomers consist of aqueous polymeric acids, such as polyacrylic acid, plus basic glass powders. They set by a neutralization reaction, but leave a substantial amount of the glass unreacted, to act as reinforcing filler. Various attempts have been made to combine the attractive properties of these materials, and the different types of hybrids of them are described. The importance of chemistry to this important branch of health care is emphasized.

  7. Effects of mercury release from amalgam dental restorations during cremation on soil mercury levels of three New Zealand crematoria

    SciTech Connect

    Nieschmidt, A.K.; Kim, N.D.

    1997-05-01

    A vast amount of research has been undertaken in the last 15-20 years on the corrosion reactions occurring in dental amalgam, release of mercury from amalgam restorations, and the toxic effects of this released mercury on the human body. However, one environmental aspect of amalgam dental restorations that has not received a great deal of attention is the release of mercury during cremation. Mercury is liberated during cremation both because dental amalgams are unstable at cremation temperatures (650-700{degrees}C) and because the free mercury metal is highly volatile. In New Zealand, 58% of deaths are followed by cremation and this figure is likely to rise in the future. This increasing use of cremation as the method of corpse disposal, coupled with the fact that each amalgam restoration is approximately 50% mercury, implies that a significant amount of mercury may be emitted into the environment every year. This study examines mercury released from crematoria in New Zealand. 20 refs., 2 figs., 5 tabs.

  8. [The prevention of mucosal lesions during oropharyngeal irradiation with a dental-filling shield].

    PubMed

    Schratter-Sehn, A U; Schmidt, W F; Kielhauser, R; Langer, H; Kärcher, K H

    1992-01-01

    In patients with metallic dental fillings radiation therapy to the oral cavity can cause mucous membrane lesions, which are more severe than expected. They appear as circumscribed erosions, opposite to metallic fillings and are caused by an increase in radiation dose through secondary radiation due to the higher density and atomic number of the filling material. This dose increase can be directly measured with 0.1 mm thin sheets of graphite-loaded TLD's (LiF, Vinten). For Co-60 gamma rays a commercial amalgam filling caused a dose increase by a factor of 1.7. The half value layer for this additional radiation was measured to be approximately 0.4 mm tissue. In order to avoid painful mucous membrane ulcerations which are even more a problem if hyperfractionated treatment schedules are used, we constructed individual dental shields for each patient. As shielding material we used a dental impression material (Optosil P+1 Bayer). This method was tested in 35 patients, in all of them circumscribed mucous membrane ulcerations could be avoided. The method proved to be fast and simple and was very well tolerated by all patients.

  9. Trends in material choice for posterior restorations in an Israeli dental school: composite resin versus amalgam.

    PubMed

    Ben-Gal, Gilad; Weiss, Ervin I

    2011-12-01

    According to a recent American Dental Association survey, posterior composite resin restorations now outnumber amalgam restorations in the United States. Dental schools around the world vary considerably in the extent to which they teach the use of composite resins. We aimed to determine if there has been an increase in the placement of posterior composite restorations in an Israeli dental school and if faculty experience affects the type of posterior restoration placed. In this retrospective study, we recorded and analyzed all the restorations performed by undergraduate students in the last five academic years at the Hebrew University Hadassah School of Dental Medicine in Jerusalem. All clinical records of student treatments between 2004 and 2009 were screened, and direct restorations were registered. Out of 6,094 posterior restorations performed during the study period, 42.3 percent were made of composite resin, increasing from 36.8 percent in 2004-05 to 48.5 percent in 2008-09, an increase of 11.7 percent. When clinical instructors were asked to state their preference if they themselves were to undergo posterior restoration, similar results were obtained. Instructors with less than ten years' experience preferred posterior composite resin restorations in 54.8 percent of the hypothetical situations, compared with 37.2 percent preferred by instructors with ten years of experience or more. It appears that the use of composite resin was influenced mainly by the prevailing trend and was not based on scientific evidence. Dental faculties should define criteria, based on up-to-date clinical studies, for using new materials, taking into consideration differences among instructors regarding treatment concept.

  10. In vitro fabrication of dental filling nanopowder by green route and its antibacterial activity against dental pathogens.

    PubMed

    Lee, Jeong-Ho; Velmurugan, Palanivel; Park, Jung-Hee; Lee, Kui-Jae; Jin, Jong-Sik; Park, Yool-Jin; Bang, Keuk-Soo; Oh, Byung-Taek

    2016-06-01

    The aim of this study was to introduce novel Sn, Cu, Hg, and Ag nanopowders (NPs) and a composite nanopowder (NP) synthesized using Salvia miltiorrhiza Bunge (SM) root extract as a reducing and capping agent to improve the antibacterial property of dental filling materials. All of the NPs obtained were characterized using a scanning transmission electron microscope (STEM), and energy dispersive X-ray (EDX) spectrum imaging was performed to map the elemental distributions of the NP composite. Fourier transform infrared (FTIR) spectroscopy was performed to identify the role of various functional groups in all of the obtained NPs and the phyto-compound responsible for the reduction of various metal ions. The X-ray diffraction (XRD) patterns clearly illustrated the crystalline phase of the synthesized NP. The antibacterial properties of the synthesized Sn, Cu, Hg, Ag, composite NP, SM root extract, and commercial amalgam powder were evaluated. The Cu, composite NP, SM root extract and Ag NP displayed excellent antibacterial activity against dental bacteria Streptococcus mutans and Lactobacillus acidophilus. The results of this study require further evaluation for signs of metal toxicity in appropriate animal models. However, the results are encouraging for the application of metal NPs as suitable alternatives for antibiotics and disinfectants, especially in dental filling materials.

  11. Cytogenetic genotoxic investigation in peripheral blood lymphocytes of subjects with dental composite restorative filling materials.

    PubMed

    Pettini, F; Savino, M; Corsalini, M; Cantore, S; Ballini, A

    2015-01-01

    Dental composite resins are biomaterials commonly used to aesthetically restore the structure and function of teeth impaired by caries, erosion, or fracture. Residual monomers released from resin restorations as a result of incomplete polymerization processes interact with living oral tissues. The objective of this study was to evaluate the genotoxicity of a common dental composite material (Enamel Plus-HFO), in subjects with average 13 filled teeth with the same material, compared to a control group (subjects having neither amalgam nor composite resin fillings). Genotoxicity assessment of composite materials was carried out in vitro in human peripheral blood leukocytes using sister-chromatid exchange (SCE) and chromosomal aberrations (CA) cytogenetic tests. The results of correlation and multiple regression analyses confirmed the absence of a relationship between SCE/cell, high frequency of SCE(HFC) or CA frequencies and exposure to dental composite materials. These results indicate that composite resins used for dental restorations differ extensively in vivo in their cytotoxic and genotoxic potential and in their ability to affect chromosomal integrity, cell-cycle progression, DNA replication and repair.

  12. Curriculum time compared to clinical procedures in amalgam and composite posterior restorations in U.S. dental schools: a preliminary study.

    PubMed

    Rey, Rosalia; Nimmo, Susan; Childs, Gail S; Behar-Horenstein, Linda S

    2015-03-01

    Dental clinicians have an expanding range of biomaterial choices for restoring tooth structure. Scientific developments in cariology, advances in dental biomaterials, and patients' esthetic concerns have led to a reduction in amalgam restorations and an increase in composite restorations. The aim of this study was to compare teaching time with students' clinical procedures in amalgam and composite posterior restorations in dental schools across the United States. Academic deans in 60 schools were invited to complete a survey that asked for the amount of instructional time for amalgam and composite posterior restorations and the number of clinical restorations performed by their Classes of 2009, 2010, and 2011. Of these 60, 12 returned surveys with complete data, for a 20% response rate. Responses from these schools showed little change in lecture and preclinical laboratory instruction from 2009 to 2011. There was a slight increase in two-surface restorations for both amalgam and composites; however, the total number of reported composite and amalgam restorations remained the same. Of 204,864 restorations reported, 53% were composite, and 47% were amalgam. There were twice as many multisurface large or complex amalgam restorations as composites. One-surface composite restorations exceeded amalgams. Among the participating schools, there was little to no change between curriculum time and clinical procedures. Findings from this preliminary study reflect a modest increase in two-surface resin-based restorations placed by dental students from 2009 to 2011 and little change in curricular time devoted to teaching amalgam restorations. The total number of posterior composite restorations placed by students in these schools was slightly higher than amalgams.

  13. Magnetic field effects on dental amalgam in divers welding and cutting electrically underwater

    SciTech Connect

    Ortendahl, T.W.; Hoegstedt, P.

    1988-11-01

    Divers have for some years been complaining about a metallic taste in the mouth while electrically welding and cutting underwater. This paper reports on results from an assessment of this problem. It was hypothesized that the magnetic fields arising from the welding or cutting current could correlate with the reported symptoms. The intraoral magnetic flux density was calculated to 1.15 mT, at 650 ADC, in a normal cutting situation. This was verified in vivo. This magnetic field was shown to contain an AC component that is a candidate for inducing secondary currents in the oral tissues and restorative materials. Five submerged divers exposed to a magnetic field of 0.35 mT did not report any metallic taste. Magnetophosphenes were reported by 1 diver. (Magnetophosphenes are luminous impressions due to excitement of the retina by a magnetic field in addition to or in place of impingement of light rays.) Only a slight shielding effect to magnetic fields was observed due to a copper-brass helmet. An in vitro model for exposure of dental amalgams to magnetic fields was designed. Recommendations for decreasing the magnetic field surrounding the diver in practical work is given.

  14. Magnetic field effects on dental amalgam in divers welding and cutting electrically underwater.

    PubMed

    Ortendahl, T W; Högstedt, P

    1988-11-01

    Divers have for some years been complaining about a metallic taste in the mouth while electrically welding and cutting underwater. This paper reports on results from an assessment of this problem. It was hypothesized that the magnetic fields arising from the welding or cutting current could correlate with the reported symptoms. The intraoral magnetic flux density was calculated to 1.15 mT, at 650 ADC, in a normal cutting situation. This was verified in vivo. This magnetic field was shown to contain an AC component that is a candidate for inducing secondary currents in the oral tissues and restorative materials. Five submerged divers exposed to a magnetic field of 0.35 mT did not report any metallic taste. Magnetophosphenes were reported by 1 diver. (Magnetophosphenes are luminous impressions due to excitement of the retina by a magnetic field in addition to or in place of impingement of light rays.) Only a slight shielding effect to magnetic fields was observed due to a copper-brass helmet. An in vitro model for exposure of dental amalgams to magnetic fields was designed. Recommendations for decreasing the magnetic field surrounding the diver in practical work is given.

  15. The spontaneous regression of palmoplantar pustulosis following removal of dental amalgams: A report of two cases.

    PubMed

    Liu, Fang; Zhang, Min; Lou, Yanfeng; Liu, Haibo; Sang, Hong

    2016-08-01

    Metal allergens are occasionally reported to be associated with palmoplantar pustulosis. We describe two severe, therapy-resistant, chronic cases of palmoplantar pustulosis induced by metal dental fillings. Both patients' clinical findings and symptoms regressed following the removal of their metal teeth. A patch test examination revealed positive reactions to metal allergens in both cases (in Case 1 the positive reactions were to cobalt chloride hexahydrate and nickel sulfate and in Case 2 the positive reaction was to nickel sulphate). Our studies suggest that metal allergens may play an important role in the pathogenesis of palmoplantar pustulosis.

  16. Evaluation of dental adhesive systems with amalgam and resin composite restorations: comparison of microleakage and bond strength results.

    PubMed

    Neme, A L; Evans, D B; Maxson, B B

    2000-01-01

    A variety of laboratory tests have been developed to assist in predicting the clinical performance of dental restorative materials. Additionally, more than one methodology is in use for many types of tests performed in vitro. This project assessed and compared results derived from two specific laboratory testing methods, one for bond strength and one for microleakage. Seven multi-purpose dental adhesives were tested with the two methodologies in both amalgam and resin composite restorations. Bond strength was determined with a punch-out method in sections of human molar dentin. Microleakage was analyzed with a digital imaging system (Image-Pro Plus, Version 1.3) to determine the extent of dye penetration in Class V preparations centered at the CEJ on both the buccal and lingual surfaces of human molar teeth. There were 32 treatment groups (n = 10); seven experimental (dental adhesives) and one control (copal varnish, 37% phosphoric acid) followed by restoration with either amalgam or resin composite. Specimens were thermocycled 500 times in 5 degrees and 55 degrees C water with a one-minute dwell time. Bond strength and microleakage values were determined for each group. ANOVA and Student-Newman-Keuls tests demonstrated an interaction between restorative material and adhesive system with a significant difference among adhesives (p < 0.05). Using a multi-purpose adhesive system resulted in both a statistically significant increase in bond strength and a statistically significant decrease in extent of microleakage (p < 0.05). The effect of the adhesive upon both microleakage and bond strength was greater in the resin composite restorations than in the amalgam restorations. Bond strength testing was more discriminating than microleakage evaluation in identifying differences among materials.

  17. British Society of Prosthodontics Debate on the Implications of the Minamata Convention on Mercury to Dental Amalgam--Should our Patients be Worried?.

    PubMed

    Austin, Rupert; Eliyas, Shiyana; Burke, F J Trevor; Taylor, Phil; Toner, James; Briggs, Peter

    2016-01-01

    In 2013, the Minamata Convention on Mercury called for a global phase-down of amalgam use, with a view to reduce environmental mercury pollution. This will significantly impact UK dentistry, given the still extensive use of amalgam in U.K. general dental practice. However, until now there has been little national discussion or debate. In Spring 2015, The British Society of Prosthodontics dedicated a significant part of its Annual Conference to debating the implications of this issue. Clinical case examples were discussed with audience interaction and voting facilitated using innovative Audience Response System Technology. A remarkable range of concerns and opinions were given. The debate elicited specific concerns amongst clinicians regarding the suitability of mercury-free alternatives to amalgam; particularly where cavities are large and extend beneath the gingival anatomy. There are also anecdotal reports of Dental Foundation (DF) dentists not being adequately taught the use of dental amalgam in undergraduate dental schools. CPD/CLINICAL RELEVANCE: Many clinicians, especially those treating patients for whom moisture control is challenging, feel that amalgam should remain available for clinicians to choose in certain clinical circumstances for the restoration of posterior teeth, even in the event of a complete phase-down.

  18. Making High-Tensile-Strength Amalgam Components

    NASA Technical Reports Server (NTRS)

    Grugel, Richard

    2008-01-01

    Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams

  19. Beeswax as dental filling on a neolithic human tooth.

    PubMed

    Bernardini, Federico; Tuniz, Claudio; Coppa, Alfredo; Mancini, Lucia; Dreossi, Diego; Eichert, Diane; Turco, Gianluca; Biasotto, Matteo; Terrasi, Filippo; De Cesare, Nicola; Hua, Quan; Levchenko, Vladimir

    2012-01-01

    Evidence of prehistoric dentistry has been limited to a few cases, the most ancient dating back to the Neolithic. Here we report a 6500-year-old human mandible from Slovenia whose left canine crown bears the traces of a filling with beeswax. The use of different analytical techniques, including synchrotron radiation computed micro-tomography (micro-CT), Accelerator Mass Spectrometry (AMS) radiocarbon dating, Infrared (IR) Spectroscopy and Scanning Electron Microscopy (SEM), has shown that the exposed area of dentine resulting from occlusal wear and the upper part of a vertical crack affecting enamel and dentin tissues were filled with beeswax shortly before or after the individual's death. If the filling was done when the person was still alive, the intervention was likely aimed to relieve tooth sensitivity derived from either exposed dentine and/or the pain resulting from chewing on a cracked tooth: this would provide the earliest known direct evidence of therapeutic-palliative dental filling.

  20. Direct metallic amalgam alternative: a research update.

    PubMed

    Eichmiller, F C; Marjenhoff, W A; Dariel, M P; Lashmore, D S

    1996-01-01

    Discussions between two group leaders at the National Institute of Standards and Technology (NIST) led to the suggestion that a mercury-free, silver-based material could be used for dental direct-filling applications. This concept brought about a new approach that, nonetheless, is still based on powder technology such as amalgams. The resulting material also retains the tin and silver components of conventional amalgams. The condensation of a loose powder mixture into a cohesive solid relies, however, on cold-welding across atomically clean silver-silver interfaces after a mild acid treatment of the surfaces. The National Institute of Dental Research (NIDR) and American Dental Association Health Foundation (ADAHF) became involved in the research in 1992, and ADAHF scientists continue to collaborate with NIST metallurgists and electrochemists toward the further development of this promising new technology.

  1. Beeswax as Dental Filling on a Neolithic Human Tooth

    PubMed Central

    Bernardini, Federico; Tuniz, Claudio; Coppa, Alfredo; Mancini, Lucia; Dreossi, Diego; Eichert, Diane; Turco, Gianluca; Biasotto, Matteo; Terrasi, Filippo; De Cesare, Nicola; Hua, Quan; Levchenko, Vladimir

    2012-01-01

    Evidence of prehistoric dentistry has been limited to a few cases, the most ancient dating back to the Neolithic. Here we report a 6500-year-old human mandible from Slovenia whose left canine crown bears the traces of a filling with beeswax. The use of different analytical techniques, including synchrotron radiation computed micro-tomography (micro-CT), Accelerator Mass Spectrometry (AMS) radiocarbon dating, Infrared (IR) Spectroscopy and Scanning Electron Microscopy (SEM), has shown that the exposed area of dentine resulting from occlusal wear and the upper part of a vertical crack affecting enamel and dentin tissues were filled with beeswax shortly before or after the individual’s death. If the filling was done when the person was still alive, the intervention was likely aimed to relieve tooth sensitivity derived from either exposed dentine and/or the pain resulting from chewing on a cracked tooth: this would provide the earliest known direct evidence of therapeutic-palliative dental filling. PMID:23028670

  2. Electrochemical impedance spectroscopy in understanding the influence of ultrasonic dental scaling on the dental structure-dental filling interface.

    PubMed

    Andrei, Mihai; Pirvu, Cristian; Demetrescu, Ioana

    2014-12-01

    The purpose of this study was to investigate the effect of ultrasonic scaling on teeth restored with a light-cured resin. Ultrasonic scaling is a very popular periodontal therapy among dentists, and used for the removal of dental plaque and calculus in order to reduce and eliminate inflammation. Given the fact that most ultrasonic devices are used at high frequencies to perform scaling, undesirable consequences, such as loss of adhesion and increase in surface roughness, may occur in teeth that have been restored with light-cured resins. Electrochemical impedance spectroscopy (EIS) and scanning electron microscopy were used to investigate the effects of ultrasonic treatments at the dental material-hard dental tissue interface. After ultrasonic scaling, EIS measurements were performed on a human tooth that had been restored with a light-cured resin filling. The data were analyzed and the influence of ultrasound was shown after visualization of the hard dental tissues and the dental material as equivalent electrical circuits. The study revealed, through EIS measurements, that ultrasonic scaling affected the resistance of the light-cured resin filling and dentin, whereas the enamel was affected only slightly. Scanning electron microscopy revealed an increase in roughness of the dental material.

  3. Use of Mercury in Dental Silver Amalgam: An Occupational and Environmental Assessment

    PubMed Central

    Jamil, Nadia; Ilyas, Samar; Qadir, Abdul; Arslan, Muhammad; Salman, Muhammad; Ahsan, Naveed; Zahid, Hina

    2016-01-01

    The objective of this study was to assess the occupational exposure to mercury in dentistry and associated environmental emission in wastewater of Lahore, Pakistan. A total of ninety-eight blood samples were collected comprising 37 dentists, 31 dental assistants, and 30 controls. Results demonstrate that the dentistry personnel contained significantly higher mean concentration of mercury in their blood samples (dentists: 29.835 µg/L and dental assistants: 22.798 µg/L) compared to that of the controls (3.2769 µg/L). The mean concentration of mercury was found maximum in the blood samples of older age group (62.8 µg/L) in dentists and (44.3 µg/L) in dental assistants. The comparison of mercury concentration among dentists, dental assistants, and controls (pairing based on their ages) revealed that the concentration increased with the age and experience among the dentists and dental assistants. Moreover, the mercury concentration in all the studied dental wastewater samples, collected from twenty-two dental clinics, was found to be exceeding the recommended discharge limit of 0.01 mg/L. Therefore, we recommend that immediate steps must be taken to ensure appropriate preventive measures to avoid mercury vapors in order to prevent potential health hazards to dentistry personnel. Strong regulatory and administrative measures are needed to deal with mercury pollution on emergency basis. PMID:27446955

  4. Bacterial leakage of mineral trioxide aggregate as compared with zinc-free amalgam, intermediate restorative material, and Super-EBA as a root-end filling material.

    PubMed

    Fischer, E J; Arens, D E; Miller, C H

    1998-03-01

    Several dye leakage studies have demonstrated the fact that mineral trioxide aggregate (MTA) leaks significantly less than other root-end filling materials. The purpose of this study was to determine the time needed for Serratia marcescens to penetrate a 3 mm thickness of zinc-free amalgam, Intermediate Restorative Material (IRM), Super-EBA, and MTA when these materials were used as root-end filling materials. Fifty-six, single-rooted extracted human teeth were cleaned and shaped with a series of .04 Taper rotary instruments (Pro-series 29 files). Once the canals were prepared in a crown down approach, the ends were resected and 48 root-end cavities were ultrasonically prepared to a 3 mm depth. The teeth were then steam sterilized. Using an aseptic technique, under a laminar air flow hood, the root-end cavities were filled with amalgam, IRM, Super-EBA, and MTA. Four root-end cavities were filled with thermoplasticized gutta-percha without a root canal sealer and served as positive controls. Another four root-end cavities were filled with sticky wax covered with two layers of nail polish and served as negative controls. The teeth were attached to presterilized (ethylene oxide gas) plastic caps, and the root ends were placed into 12-ml vials of phenol red broth. Using a micropipette, a tenth of a milliliter of S. marcescens was placed into the root canal of each tooth. To test the sterility of the apparatus set-up, the root canals of two teeth with test root-end filling materials and one tooth from the positive and negative control groups were filled with sterile saline. The number of days required for S. marcescens to penetrate the four root-end filling materials and grow in the phenol red broth was recorded and analyzed. Most of the samples filled with zinc-free amalgam leaked bacteria in 10 to 63 days. IRM began leaking 28 to 91 days. Super-EBA began leaking 42 to 101 days. MTA did not begin leaking until day 49. At the end of the study, four of the MTA samples

  5. Cytotoxicity of dental composite (co)monomers and the amalgam component Hg(2+) in human gingival fibroblasts.

    PubMed

    Reichl, Franz-Xaver; Simon, Sabine; Esters, Magalie; Seiss, Mario; Kehe, Kai; Kleinsasser, Norbert; Hickel, Reinhard

    2006-08-01

    Unpolymerized resin (co)monomers or mercury (Hg) can be released from restorative dental materials (e.g. composites and amalgam). They can diffuse into the tooth pulp or the gingiva. They can also reach the gingiva and organs by the circulating blood after the uptake from swallowed saliva. The cytotoxicity of dental composite components hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (Bis-GMA) as well as the amalgam component Hg(2+) (as HgCl(2)) and methyl mercury chloride (MeHgCl) was investigated on human gingival fibroblasts (HGFs) at two time intervals. To test the cytotoxicity of substances, the bromodeoxyuridine (BrdU) assay and the lactate dehydrogenase (LDH) assay were used. The test substances were added in various concentrations and cells were incubated for 24 or 48 h. The EC(50) values were obtained as half-maximum-effect concentrations from fitted curves. Following EC(50) values were found [BrdU: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 8.860 (0.440)/6.600(0.630), TEGDMA 1.810(0.130)/1.220(0.130), UDMA 0.120(0.010)/0.140(0.010), BisGMA 0.060(0.004)/0.040(0.002), HgCl(2) 0.015(0.001)/0.050(0.006), and MeHgCl 0.004(0.001)/0.005(0.001). Following EC(50) values were found [LDH: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 9.490(0.300)/7.890(1.230), TEGDMA 2.300(0.470)/1.950(0.310), UDMA 0.200(0.007)/0.100(0.007), BisGMA 0.070(0.005)/0.100(0.002), and MeHgCl 0.014(0.006)/0.010(0.003). In both assays, the following range of increased toxicity was found for composite components (24 and 48 h): HEMA < TEGDMA < UDMA < BisGMA. In both assays, MeHgCl was the most toxic substance. In the BrdU assay, Hg(2+) was about fourfold less toxic than MeHgCl but Hg(2+) was about fourfold more toxic than BisGMA. In the BrdU test, a significantly (P<0.05) decreased toxicity was observed for Hg(2+) at 48 h, compared to the 24 h Hg(2+)-exposure. A time depending

  6. [Benefits of antioxidant agents' use for dental filling consequent to the endo-bleaching].

    PubMed

    Kobakhidze, G D; Vadachkoriia, N R; Tkhilava, N G

    2006-08-01

    Efficacy of antioxidant agents' use after dental endo bleaching was studied in clinical trial. The study enrolled 169 patients, ranging age 16 to 60 years in age. The patients were randomized into 2 groups: control (63) and trial (106). In patients of the control group tooth cavity was left open after endo bleaching, and was filled only after 7 days. In patients of the trial group antioxidant agent was administered into the dental tissues consequently to the endo bleaching, and the cavity was filled immediately. Assessment of the immediate and distant effects revealed unwanted results of postponed dental filling (control group) in terms of tooth color stability and forming micro cracks. Results of antioxidant use and immediate dental filling after endo bleaching have proven our earlier experimental studies on benefits of antioxidant use to be right. Based on the results of our clinical study we can recommend use of antioxidant after endo bleaching to achieve successful dental fillings in clinical practice.

  7. Performance of a gaseous detector based energy dispersive X-ray fluorescence imaging system: Analysis of human teeth treated with dental amalgam

    NASA Astrophysics Data System (ADS)

    Silva, A. L. M.; Figueroa, R.; Jaramillo, A.; Carvalho, M. L.; Veloso, J. F. C. A.

    2013-08-01

    Energy dispersive X-ray fluorescence (EDXRF) imaging systems are of great interest in many applications of different areas, once they allow us to get images of the spatial elemental distribution in the samples. The detector system used in this study is based on a micro patterned gas detector, named Micro-Hole and Strip Plate. The full field of view system, with an active area of 28 × 28 mm2 presents some important features for EDXRF imaging applications, such as a position resolution below 125 μm, an intrinsic energy resolution of about 14% full width at half maximum for 5.9 keV X-rays, and a counting rate capability of 0.5 MHz. In this work, analysis of human teeth treated by dental amalgam was performed by using the EDXRF imaging system mentioned above. The goal of the analysis is to evaluate the system capabilities in the biomedical field by measuring the drift of the major constituents of a dental amalgam, Zn and Hg, throughout the tooth structures. The elemental distribution pattern of these elements obtained during the analysis suggests diffusion of these elements from the amalgam to teeth tissues.

  8. High Tensile Strength Amalgams for In-Space Repair and Fabrication

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.

    2005-01-01

    Amalgams are defined as an alloy of mercury with one or more other metals. These, along with those based on gallium (also liquid at near room temperature), are widely used in dental practice as a tooth filling material. Amalgams have a number of useful attributes that indude room temperature compounding. corrosion resistance, dimensional stability, and good compressive strength. These properties well serve dental needs but, unfortunately, amalgams have extremely poor tensile strength, a feature that severely limits their applications. The work presented here demonstrates how, by modifying particle geometry, the tensile strength of amalgams can be increased and thus extending the range of potential applications. This is relevant to, for example, the freeform fabrication of replacement parts that might be necessary during an extended space mission. Advantages, i.e. Figures-of-Merit. include the ability to produce complex parts, minimum crew interaction, high yield - minimum wasted material, reduced gravity compatibility, minimum final finishing, safety, and minimum power consumption.

  9. High Tensile Strength Amalgams for In-Space Fabrication and Repair

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.

    2006-01-01

    Amalgams are well known for their use in dental practice as a tooth filling material. They have a number of useful attributes that include room temperature fabrication, corrosion resistance, dimensional stability, and very good compressive strength. These properties well serve dental needs but, unfortunately, amalgams have extremely poor tensile strength, a feature that severely limits other potential applications. Improved material properties (strength and temperature) of amalgams may have application to the freeform fabrication of repairs or parts that might be necessary during an extended space mission. Advantages would include, but are not limited to: the ability to produce complex parts, a minimum number of processing steps, minimum crew interaction, high yield - minimum wasted material, reduced gravity compatibility, minimum final finishing, safety, and minimum power consumption. The work presented here shows how the properties of amalgams can be improved by changing particle geometries in conjunction with novel engineering metals.

  10. Preparation of dental amalgam and spectral diagnosis of mercury in plasmas-laser in the region of 250 nm - 850 nm

    NASA Astrophysics Data System (ADS)

    De la Ossa, A.; Pacheco, P.; Sarmiento, R.

    2013-11-01

    In this paper we presents results of the spectral study of plasmas-laser of dental amalgam by technique Laser-induced Breakdown Spectroscopy (LIBS). Plasmas were generated focusing the beam of a Nd: YAG laser on the matrix of the mixture Ag-Sn-Cu and on amalgams with different proportions of mercury (3:2, 5:2, 6:2). Based on the spectral results and reported atomic parameters, became estimation of electron temperature plasmas- laser and their behavior with the concentration of Hg. The estimated values of the electron temperature for the respective proportions were 20 846 K, 19 139 K and 16 872 K, using the distribution of population of Boltzmann energy levels associated with spectral lines, considering conditions Local Thermodinamic Equilibrium (LTE) of plasmas.

  11. Ultra-high-resolution dual-source CT for forensic dental visualization-discrimination of ceramic and composite fillings.

    PubMed

    Jackowski, C; Wyss, M; Persson, A; Classens, M; Thali, M J; Lussi, A

    2008-07-01

    Dental identification is the most valuable method to identify human remains in single cases with major postmortem alterations as well as in mass casualties because of its practicability and demanding reliability. Computed tomography (CT) has been investigated as a supportive tool for forensic identification and has proven to be valuable. It can also scan the dentition of a deceased within minutes. In the present study, we investigated currently used restorative materials using ultra-high-resolution dual-source CT and the extended CT scale for the purpose of a color-encoded, in scale, and artifact-free visualization in 3D volume rendering. In 122 human molars, 220 cavities with 2-, 3-, 4- and 5-mm diameter were prepared. With presently used filling materials (different composites, temporary filling materials, ceramic, and liner), these cavities were restored in six teeth for each material and cavity size (exception amalgam n = 1). The teeth were CT scanned and images reconstructed using an extended CT scale. Filling materials were analyzed in terms of resulting Hounsfield units (HU) and filling size representation within the images. Varying restorative materials showed distinctively differing radiopacities allowing for CT-data-based discrimination. Particularly, ceramic and composite fillings could be differentiated. The HU values were used to generate an updated volume-rendering preset for postmortem extended CT scale data of the dentition to easily visualize the position of restorations, the shape (in scale), and the material used which is color encoded in 3D. The results provide the scientific background for the application of 3D volume rendering to visualize the human dentition for forensic identification purposes.

  12. DEVELOPMENT AND VERIFICATION OF NEW SOLID DENTAL FILLING TEMPORARY MATERIALS CONTAINING ZINC. FORMULA DEVELOPMENT STAGE.

    PubMed

    Pytko-Polończyk, Jolanta; Antosik, Agata; Zajac, Magdalena; Szlósarczyk, Marek; Krywult, Agnieszka; Jachowicz, Renata; Opoka, Włodzimierz

    2016-01-01

    Caries is the most popular problem affecting teeth and this is the reason why so many temporary dental filling materials are being developed. An example of such filling is zinc oxide paste mixed with eugenol, Thymodentin and Coltosol F®. Zinc-oxide eugenol is used in dentistry because of its multiplied values: it improves heeling of the pulp by dentine bridge formation; has antiseptic properties; is hygroscopic. Because of these advantages compouds of zinc oxide are used as temporary fillings, especially in deep caries lesions when treatment is oriented on support of vital pulp. Temporary dental fillings based on zinc oxide are prepared ex tempone by simple mixing powder (Thymodentin) and eugenol liqiud together or a ready to use paste Coltosol F®. Quantitative composition depends mainly on experience of person who is preparing it, therefore, exact qualitative composition of dental fillings is not replicable. The main goal of the study was to develop appropriate dental fillings in solid form containing set amount of zinc oxide. Within the study, the influence of preparation method on solid dental fillings properties like mechanical properties and zinc ions release were examined.

  13. Dosimetric consideration for patients with dental filling materials undergoing irradiation of oral cavity using RapidArc: challenges and solution

    NASA Astrophysics Data System (ADS)

    Mail, Noor; Albarakati, Y.; Khan, M. Ahmad; Saeedi, F.; Safadi, N.; Al-Ghamdi, S.; Saoudi, A.

    2012-03-01

    In this study, we investigate the effect of dental filling materials (DFM) on RapidArcTM treatment plans and delivery in a patient undergoing radiotherapy treatment. The presence of DFM creates uncertainties in CT number and causes long streaking artifacts in the reconstructed images which greatly affect the dose distribution inside the oral cavity. The influence of extensive dental filling artifacts on dose distribution was performed using a geometrically well defined head and neck IMRT verification phantom (PTW, Freiburg, Germany) together with inserts from DFM (Amalgam, 11.3 g/cm3). The phantom was scanned using Siemens SOMATOM Sensation CT simulator (Siemens AG, Germany) under standard head and neck imaging protocol (120 kV, 120 mAs, voxel size 1×1×2 mm3). Three RapidArcTM plans were created in the Varian Eclipse treatment planning System (TPS) to treat oral cavity using the same CT dataset including; 1) raw CT image, 2) streaking artifacts replaced with a mask of 10 HU and 3) 2 cm thick 6000 HU virtual filter (a volume around the teeth in TPS to mimic extra attenuation). The virtual filter thickness optimization was purely based on measured PDD data acquired with DFM and the calculation in Eclipse Planning System using direct beam. The dose delivery and distribution for the three plans was verified using Gafchromic EBT2 (International Specialty Product, Wayne, NJ, USA) film measurements. The artifact mask and virtual filter around the teeth in the planning was found very useful to reduce the discrepancies between the dose plan and delivery. From clinical point of view, these results can be helpful to understand the increase of mucositis in patient having DFM, and further investigation is underway for clinical solution.

  14. Study of the short-term release of the ionic fraction of heavy metals from dental amalgam into synthetic saliva, using anodic stripping voltammetry with microelectrodes.

    PubMed

    Sanna, Gavino; Pilo, Maria I; Piu, Paola C; Spano, Nadia; Tapparo, Andrea; Campus, Guglielmo G; Seeber, Renato

    2002-11-12

    The present paper describes a fast and reproducible procedure, employing differential pulse stripping analysis technique with graphite microelectrodes, for the quantitative evaluation of the ionic fraction of heavy metals (namely Hg, Cu, and Zn) released from dental amalgams into synthetic saliva during 6-90 h contact between amalgam and saliva, after completion of the dental restoration (short-term release). The Zn(2+) concentration was evaluated by linear calibration, whereas Cu(2+) and Hg(2+) contents were estimated by the standard additions method. While the concentration of Zn(2+) ion does not increase significantly anymore after a 6-h contact (values from 288+/-12 to 346+/-12 mugdm(-3) at time of contact from 6 to 90 h, respectively), in the same time interval the concentration of both Cu(2+) and Hg(2+) ions progressively increases (from 38+/-6 to 197+/-4 mugdm(-3) and from 15+/-3 to 101+/-2 mugdm(-3), respectively). The results of the release tests reveal that Hg concentration is at the highest level of risk (HBM III), as identified by the three human biomonitoring categories suggested by the Institut für Wasser-, Boden- und Lufthygiene des Umweltbundesamtes (Germany) for the estimation of potential harmful effects on health due to exposure to heavy metals.

  15. Phase down of amalgam

    PubMed Central

    AL-Rabab’ah, Mohammad A.; Bustani, Mohammad A.; Khraisat, Ameen S.; Sawair, Faleh A.

    2016-01-01

    Objectives To assess the knowledge of Jordanian dentists toward phase down of dental amalgam as recommended by the Minamata Convention, and their training and competency in placing posterior composites. Methods This study was conducted through structured questionnaire interviews with randomly selected cohort of dentists in Jordan between March 2015 and June 2015. Out of 230 dentists who were invited, 196 (85.2%) agreed to participate. Dentists were asked if they know about the Minamata Convention. They were also asked about their training in placement of posterior composite. Results Out of the 196 interviewed, only 13.8% know about Minamata Convention and 17% had an undergraduate training in favor of placing composites in posterior teeth. Approximately 50% of those dentists were not trained in using rubber dam when placing posterior composites, while only 38.3% had training in sectional matrix placement. Undergraduate training did not influence (p=0.00) the dentists’ decision to remove old amalgam based on patient’s demands. Only 28.1% were of the opinion of discontinuing the use of amalgam due to its alleged health and environmental hazards. There was no general agreement on the type of composite, liner, and bonding strategy when placing posterior composites. Conclusion Dentists are not well informed on the Minamata Convention and the phase down of amalgam. Training in posterior composite placement should be given more room in undergraduate curriculum and continuous dental education. PMID:27874155

  16. Mechanical Properties Comparing Composite Fiber Length to Amalgam

    PubMed Central

    Petersen, Richard C.; Liu, Perng-Ru

    2016-01-01

    Photocure fiber-reinforced composites (FRCs) with varying chopped quartz-fiber lengths were incorporated into a dental photocure zirconia-silicate particulate-filled composite (PFC) for mechanical test comparisons with a popular commercial spherical-particle amalgam. FRC lengths included 0.5-mm, 1.0 mm, 2.0 mm, and 3.0 mm all at a constant 28.2 volume percent. Four-point fully articulated fixtures were used according to American Standards Test Methods with sample dimensions of 2×2×50 mm3 across a 40 mm span to provide sufficient Euler flexural bending and prevent top-load compressive shear error. Mechanical properties for flexural strength, modulus, yield strength, resilience, work of fracture, critical strain energy release, critical stress intensity factor, and strain were obtained for comparison. Fiber length subsequently correlated with increasing all mechanical properties, p < 1.1×10−5. Although the modulus was significantly statistically higher for amalgam than all composites, all FRCs and even the PFC had higher values than amalgam for all other mechanical properties. Because amalgams provide increased longevity during clinical use compared to the standard PFCs, modulus would appear to be a mechanical property that might sufficiently reduce margin interlaminar shear stress and strain-related microcracking that could reduce failure rates. Also, since FRCs were tested with all mechanical properties that statistically significantly increased over the PFC, new avenues for future development could be provided toward surpassing amalgam in clinical longevity. PMID:27642629

  17. SU-E-T-365: Dosimetric Impact of Dental Amalgam CT Image Artifacts On IMRT and VMAT Head and Neck Plans

    SciTech Connect

    Cao, N; Young, L; Parvathaneni, U; Liao, J; Richard, P; Ford, E; Sandison, G

    2014-06-01

    Purpose: The presence of high density dental amalgam in patient CT image data sets causes dose calculation errors for head and neck (HN) treatment planning. This study assesses and compares dosimetric variations in IMRT and VMAT treatment plans due to dental artifacts. Methods: Sixteen HN patients with similar treatment sites (oropharynx), tumor volume and extensive dental artifacts were divided into two groups: IMRT (n=8, 6 to 9 beams) and VMAT (n=8, 2 arcs with 352° rotation). All cases were planned with the Pinnacle 9.2 treatment planning software using the collapsed cone convolution superposition algorithm and a range of prescription dose from 60 to 72Gy. Two different treatment plans were produced, each based on one of two image sets: (a)uncorrected; (b)dental artifacts density overridden (set to 1.0g/cm{sup 3}). Differences between the two treatment plans for each of the IMRT and VMAT techniques were quantified by the following dosimetric parameters: maximum point dose, maximum spinal cord and brainstem dose, mean left and right parotid dose, and PTV coverage (V95%Rx). Average differences generated for these dosimetric parameters were compared between IMRT and VMAT plans. Results: The average absolute dose differences (plan a minus plan b) for the VMAT and IMRT techniques, respectively, caused by dental artifacts were: 2.2±3.3cGy vs. 37.6±57.5cGy (maximum point dose, P=0.15); 1.2±0.9cGy vs. 7.9±6.7cGy (maximum spinal cord dose, P=0.026); 2.2±2.4cGy vs. 12.1±13.0cGy (maximum brainstem dose, P=0.077); 0.9±1.1cGy vs. 4.1±3.5cGy (mean left parotid dose, P=0.038); 0.9±0.8cGy vs. 7.8±11.9cGy (mean right parotid dose, P=0.136); 0.021%±0.014% vs. 0.803%±1.44% (PTV coverage, P=0.17). Conclusion: For the HN plans studied, dental artifacts demonstrated a greater dose calculation error for IMRT plans compared to VMAT plans. Rotational arcs appear on the average to compensate dose calculation errors induced by dental artifacts. Thus, compared to VMAT, density

  18. A galvanic study of different amalgams.

    PubMed

    Wang Chen, C P; Greener, E H

    1977-01-01

    Due to the difference in open circuit potential (OCP) versus SCE for Aristaloy amalgam (-969 mV) and Dispersalloy amalgam (-549 mV) in Ringer's solution at 25 degrees C, a galvanic cell was created with Dispersalloy amalgam as cathode and Aristaloy amalgam as anode. The galvanic corrosion current was studied as a function of time for the above cell as well as for a cell of type III dental gold (OCP is +0-5 mV) versus Aristaloy amalgam. The initial corrosion current of the latter cell (105 micronA) is about twice that for the cell of Aristaloy amalgam versus Dispersalloy amalgam (54 micronA), however, their passivating behaviour is quite similar. Also, an interrupted galvanic corrosion test simulating the oral 'make and break' situation was performed. A much higher corrosion current than the steady state was found when the two electrodes resumed contact.

  19. [Black or white--Which choice for the molars? Part 2. Which does one choose for the restoration of posterior teeth: amalgam or composite?].

    PubMed

    De Moor, Roeland; Delmé, Katleen

    2008-01-01

    The two direct dental restorative materials most commonly used today are silver-mercury amalgam and resin-based composite. The survival of dental amalgam restorations is twice as high than for composite fillings: polymerisation shrinkage, deficient marginal adaptation, higher wear rates, defective contact points leading to food impaction, insufficiently converted composite at the bottom of the cavity are problems that cannot be underestimated when using resin-composite. This does not imply that there is no weakness for amalgam: the need for retentive cavities at the cost of healthy tooth substance, weakening of the tooth's strength by cutting through the tooth crown's ridges, the risk of fracture of remaining tooth substance (mostly buccal and lingual surfaces) as the result of the cavity design, and the lack of adhesion between amalgam and tooth substance. Retaining a tooth's strength by the replacement of amalgam by resin-composites is not always the correct solution. In this respect, it can be questioned whether it is not appropriate to repair failing (extensive) amalgam restorations as to replace them with resin-composites. Research in this respect has demonstrated that dentists still are not convinced of this treatment option. Restoring a tooth in its original build-up or structure and function within the oral cavity is the basis of the biomimetic principle: the use of composite appears to be more obvious than restoring with amalgam. In the present survey pro's and con's of amalgams and resin-composites for the restoration of posterior teeth are weighted. The conclusion demonstrates that there is still a place for dental amalgam in modern restorative dentistry when plastic filling materials are used for the direct tooth repair or restoration.

  20. A 24-month Evaluation of Amalgam and Resin-Based Composite Restorations: Findings from The National Dental Practice-Based Research Network

    PubMed Central

    McCracken, Michael S.; Gordan, Valeria V.; Litaker, Mark S.; Funkhouser, Ellen; Fellows, Jeffrey L.; Shamp, Douglass G.; Qvist, Vibeke; Meral, Jeffrey S.; Gilbert, Gregg H.

    2013-01-01

    Background Knowing which factors influence restoration longevity can help clinicians make sound treatment decisions. The authors analyzed data from the National Dental Practice-Based Research Network to identify predictors of early failures of amalgam and resin-based composite (RBC) restorations. Methods This prospective cohort study gathered information from clinicians and offices participating in the network. Clinicians completed a baseline data collection form at the time of restoration placement, and annually thereafter. Data collected included patient factors, practice factors, and dentist factors, and were analyzed using mixed-model logistic regression. Results A total of 226 practitioners followed 6,218 direct restorations in 3,855 patients; 386 restorations failed (6.6 percent) during the mean follow-up period of 23.7 (SD 8.8) months. The number of tooth surfaces restored at baseline predicted subsequent restoration failure; large restorations were over 4 times more likely to fail. Material was not significantly associated with longevity; neither was tooth type. Patient age was highly associated with failure (p<0.0001). The failure rate for children was 5 percent, compared to 12 percent in persons 65 years old or older. Dentist gender and practice workload were significantly associated with restoration longevity. Conclusions In this prospective cohort study, these factors significantly predicted an increased failure rate for amalgam and RBC restorations: older patient age and a higher number of surfaces restored at baseline, with other key baseline variables taken into account. Material choice was not significantly predictive in these early results. Clinical Implications Understanding risk factors for early restoration failure may lead to more-effective patient care. PMID:23729455

  1. Radiographic Evaluation of Root Canal Fillings Accomplished by Undergraduate Dental Students

    PubMed Central

    Yavari, Hamidreza; Samiei, Mohammad; Shahi, Shahriar; Borna, Zahra; Abdollahi, Amir Ardalan; Ghiasvand, Negar; Shariati, Gholamreza

    2015-01-01

    Introduction: The purpose of this study was to evaluate the radiographic quality of root canal fillings by fourth-, fifth-, and sixth-year undergraduate students at Tabriz Faculty of Dentistry between 2006 and 2012. Methods and Materials: A total of 1183 root canal fillings in 620 teeth were evaluated by two investigators (and in case of disagreement by a third investigator) regarding the presence or absence of under-fillings, over-fillings and perforations. For each tooth, preoperative, working and postoperative radiographs were checked. The Pearson’s chi-square test was used for statistical evaluation of the data. Inter-examiner agreement was measured by Cohen’s kappa (k) values. The level of significance was set at 0.05. Results: Total frequencies of over-filling, under-filling and perforation were 5.6%, 20.4% and 1.9%, respectively. There were significant differences between frequencies of over- and under-fillings (P<0.05). Unacceptable quality, under- and over-fillings were detected in 27.9% of 1183 evaluated canals. Conclusion: The technical quality of root canal therapies performed by undergraduate dental students using step-back preparation and lateral compaction techniques was unacceptable in almost one-fourth of the cases. PMID:25834598

  2. The impacts of dental filling materials on RapidArc treatment planning and dose delivery: Challenges and solution

    SciTech Connect

    Mail, Noor; Al-Ghamdi, S.; Saoudi, A.; Albarakati, Y.; Ahmad Khan, M.; Saeedi, F.; Safadi, N.

    2013-08-15

    Purpose: The presence of high-density material in the oral cavity creates dose perturbation in both downstream and upstream directions at the surfaces of dental filling materials (DFM). In this study, the authors have investigated the effect of DFM on head and neck RapidArc treatment plans and delivery. Solutions are proposed to address (1) the issue of downstream dose perturbation, which might cause target under dosage, and (2) to reduce the upstream dose from DFM which may be the primary source of mucositis. In addition, an investigation of the clinical role of a custom-made plastic dental mold/gutter (PDM) in sparing the oral mucosa and tongue reaction is outlined.Methods: The influence of the dental filling artifacts on dose distribution was investigated using a geometrically well-defined head and neck intensity modulated radiation therapy (IMRT) verification phantom (PTW, Freiberg, Germany) with DFM inserts called amalgam, which contained 50% mercury, 25% silver, 14% tin, 8% copper, and 3% other trace metals. Three RapidArc plans were generated in the Varian Eclipse System to treat the oral cavity using the same computer tomography (CT) dataset, including (1) a raw CT image, (2) a streaking artifacts region, which was replaced with a mask of 10 HU, and (3) a 2 cm-thick 6000 HU virtual filter [a volume created in treatment planning system to compensate for beam attenuation, where the thickness of this virtual filter is based on the measured percent depth dose (PDD) data and Eclipse calculation]. The dose delivery for the three plans was verified using Gafchromic-EBT2 film measurements. The custom-made PDM technique to reduce backscatter dose was clinically tested on four head and neck cancer patients (T3, N1, M0) with DFM, two patients with PDM and the other two patients without PDM. The thickness calculation of the PDM toward the mucosa and tongue was purely based on the measured upstream dose. Patients’ with oral mucosal reaction was clinically examined

  3. Biological mercury measurements before and after administration of a chelator (DMPS) and subjective symptoms allegedly due to amalgam.

    PubMed

    Schuurs, A; Exterkate, R; ten Cate, J M; ten Cate, B

    2000-12-01

    The aim of the study was to explore multivariately the relationship between subjective symptoms allegedly due to amalgam and mercury measurements before and after administration of a chelator. Of 120 participants, the mercury concentrations in urine (U-Hg) and plasma (P-Hg) before and after a chelating agent or placebo were determined as were the numbers of fillings and symptoms allegedly due to subjective symptoms. The dental status was charted. Blood was analysed on 13 parameters. The analysis revealed neither the parameters in blood nor the subjective symptoms to be associated with a dimension dominated by 'mercury indicators'. The final analysis was therefore performed with 'number of subjective symptoms' and enabled to distinguish two subsamples. One subsample was characterised by > 2 subjective "symptoms", highest scores for U-Hg, P-Hg and filled surfaces, and chewing gum for > 1 h a day. The other subsample comprised the subjects with few filled surfaces and low U-Hg and P-Hg, but was not characterised by "no subjective symptoms". The chelator was considered neither to invalidate nor to improve these findings and was concluded not to be helpful in diagnosing "symptoms". The chelator caused side effects in 42% of the subjects and the placebo in 27%. A relationship between amalgam fillings and subjective symptoms could not be shown. Therefore, the mere fact of knowing to have amalgam fillings was assumed to be the reason why subjective symptoms were attributed to amalgam and side effects were ascribed to the treatment.

  4. Low-intensity lasers, modern filling materials, and bonding systems influence on mineral metabolism of hard dental tissues

    NASA Astrophysics Data System (ADS)

    Kunin, Anatoly A.; Yesaulenko, I. E.; Zoibelmann, M.; Pankova, Svetlana N.; Ippolitov, Yu. A.; Oleinik, Olga I.; Popova, T. A.; Koretskaya, I. V.; Shumilovitch, Bogdan R.; Podolskaya, Elana E.

    2001-10-01

    One of the main reasons of low quality filling is breaking Ca-P balance in hard tissues. Our research was done with the purpose of studying the influence of low intensity lasers, diodic radiation, the newest filling and bonding systems on the processes of mineral metabolism in hard dental tissues while filling a tooth. 250 patients having caries and its compli-cations were examined and treated. Our complex research included: visual and instrumental examination, finding out the level of oral cavity hygiene, acid enamel biopsy, scanning electronic microscopy and X-ray spectrum microanalysis. Filling processes may produce a negative effect on mineral metabolism of hard dental tissues the latter is less pronounced when applying fluoride-containing filling materials with bonding systems. It has also been found that bonding dentin and enamel systems are designed for both a better filling adhesion (i.e. mechanical adhesion) and migration of useful microelements present in them by their sinking into hard dental tissues (i.e. chemical adhesion). Our research showed a positive influence of low intensity laser and diodic beams accompanying the use of modern filling and bonding systems on mineral metabolism of hard dental tissues.

  5. Backscattering from dental restorations and splint materials during therapeutic radiation

    SciTech Connect

    Farman, A.G.; Sharma, S.; George, D.I.; Wilson, D.; Dodd, D.; Figa, R.; Haskell, B.

    1985-08-01

    Models were constructed to simulate as closely as possible the human oral cavity. Radiation absorbed doses were determined for controls and various test situations involving the presence of dental restorative and splint materials during cobalt-60 irradiation of the models. Adjacent gold full crowns and adjacent solid dental silver amalgam cores both increased the dose to the interproximal gingivae by 20%. Use of orthodontic full bands for splinting the jaws increased the dose to the buccal tissues by an average of 10%. Augmentation of dose through backscatter radiation was determined to be only slight for intracoronal amalgam fillings and stainless steel or plastic bracket splints.

  6. Distribution of toxic elements in teeth treated with amalgam using μ-energy dispersive X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Guerra, M.; Ferreira, C.; Carvalho, M. L.; Santos, J. P.; Pessanha, S.

    2016-08-01

    Over the years, the presence of mercury in amalgam fillings has raised some safety concerns. Amalgam is one of the most commonly used tooth fillings and contains approximately 50% of elemental mercury and 50% of other metals, mostly silver, tin and copper. Amalgam can release small amounts of mercury vapor over time, and patients can absorb these vapors by inhaling or ingesting them. In this study, 10 human teeth treated with dental amalgam were analyzed using energy dispersive X-ray fluorescence (EDXRF) to study the diffusion of its constituents, Ag, Cu, Sn and Hg. The used EDXRF setup, makes use of a polycapillary lens to focus radiation up to 25 μm allowing the mapping of the elemental distribution in the samples. Quantification was performed using the inbuilt software based on the Fundamental Parameters method for bulk samples, considering a hydroxyapatite matrix. The teeth were longitudinally cut and each slice was scanned from the surface enamel to the inner region (dentin and pulp cavity). Mercury concentration profiles show strong levels of this element close to the amalgam region, decreasing significantly in the dentin, and increasing again up to 40,000 μg·g- 1 in the cavity were the pulp used to exist when the tooth was vital.

  7. Three-dimensional visualization of composite fillings for dental identification using CT images

    PubMed Central

    Sakuma, A; Saitoh, H; Makino, Y; Inokuchi, G; Hayakawa, M; Yajima, D; Iwase, H

    2012-01-01

    Objectives This study aimed to discriminate between enamel and composite resins by differences in Hounsfield units shown on 16 section multidetector CT (MDCT) images taken of unidentified bodies. Methods First, we determined the Hounsfield units of composite resins in 15 extracted human teeth. We then filled a single cavity prepared in each of the teeth with one of five different types of composite resins, and scanned the teeth using our routine post-mortem CT protocol for the head and neck. Obtained data were transferred to a radiological workstation and reconstructed. Furthermore, post-mortem CT images of the head of three unidentified bodies were reconstructed in the same manner. Results Four types of composite resins containing radio-opaque fillers showed a constant value of 4000 HU, and one radiolucent composite resin showed values in the range of 660–800 HU in the extracted teeth. Pixels at 4000 HU indicated that the composite resins were selected and visualized as three-dimensional colour images. Composite resins could be visualized on reconstructed images of the three unidentified bodies, and the sites visualized matched those noted on the forensic dental charts. Conclusions Discriminating enamel and composite resins containing radio-opaque materials was difficult because of their similar Hounsfield unit values. However, we did succeed in visualizing the composite resins despite limitations of the CT scale. CT reconstructed images can contribute to dental identification, particularly in cases where it is difficult to detect composite resins on external investigation, and these images can be prepared during routine dental identification work. PMID:22868297

  8. Clinical evaluation of a newly developed method for avoiding artifacts caused by dental fillings on X-ray CT.

    PubMed

    Nakae, Yasuo; Sakamoto, Kiyoshi; Minamoto, Takahiro; Kamakura, Toshiko; Ogata, Yuji; Matsumoto, Mitsuhiro; Johkou, Takeshi

    2008-01-01

    To evaluate the clinical usefulness of gantry tilt scanning as an image reconstruction technique for avoiding artifacts caused by metallic dental fillings. Gantry tilt scanning was used with multidetector-row computed tomography for imaging in patients with dental fillings. Using a novel PC-based program, the oblique images obtained were reconstructed to transverse images using nearest neighbor and bilinear interpolation methodologies in order to avoid metallic streak artifacts. Coronal images were reformatted with the reconstructed transverse images, and the continuity of the reconstructed images was evaluated. Gantry tilt scanning was performed in 12 patients with metal artifacts, and the original and reconstructed images were classified into four grades and assessed by two radiologists. Results of the clinical evaluation indicated that the original images with artifacts, only 4% had good image quality in the region around the medial pterygoid muscle, only 8% depicted areas around the internal carotid artery and internal jugular vein, and only 12% could depict the areas around the parotid gland in the clinical evaluation. These values were improved to 60, 96, and 100%, respectively, in the reconstructed transverse images. Gantry tilt scanning as an image reconstruction technique improves image quality and removes most, if not all, artifacts caused by metallic dental fillings. The resulting images can be used in the evaluation of oropharyngeal lesions in patients with dental fillings.

  9. Dental fractures on acute exposure to high altitude.

    PubMed

    Zadik, Yehuda; Einy, Shmuel; Pokroy, Russell; Bar Dayan, Yaron; Goldstein, Liav

    2006-06-01

    There is little in the literature on dental restoration breakage in the aviation environment since reports of problems in combat aviators in War World II. We report two cases of dental fractures during acute exposure to a hypobaric environment. Case 1 was a young officer who suffered an amalgam restoration breakage during a 25,000-ft decompression chamber simulation. Case 2 occurred in an experienced aviator who had a tooth cusp fracture in a molar with a defective amalgam restoration during an unpressurized helicopter flight to 18,000 ft. In both cases, after removing the defective fillings, deep secondary caries were found; both teeth were successfully restored. Because hard-tissue tooth fracture during a high-altitude flight is a rare event, few flight surgeons or dentists are familiar with this phenomenon. We recommend regular dental examinations with careful assessment of previous dental restorations in aircrew subject to decompression.

  10. [Allergies to dental materials and dental pharmacologic agents].

    PubMed

    Gall, H

    1983-07-01

    Allergic reactions to dental materials and remedies cause stomatitis in the patient and a contact dermatitis in the dental personnel. Topical contact (acrylic resin denture materials, heat accumulation, plaques on the denture) and endogenic (symptom of internal and psychiatric illnesses) factors are the cause for denture sore mouth. In metallic alloys corrosions and electric currents can effect an irritation to the oral mucosa. The application of amalgam fillings can possibly result in a mercurialism. Dental remedies used for treatment of wounds and dental roots are potent sensitizers. Surface anesthetics with tetracaine are the most frequent contact allergens for dentists. Injectable local anesthetics produce anaphylactic type reactions as well as toxic side-effects in the patient.

  11. Adhesives, silver amalgam.

    PubMed

    1995-09-01

    The most recent advancement in silver amalgam is use of resin formulations to bond metal to tooth both chemically &/or physically, Since, historically, amalgam has been used successfully without adhesion to tooth, obvious clinical question is: Why is bonding now desirable? Two major clinical reasons to bond are: (1) Adhesive can increase fracture resistance of amalgam restored teeth & decrease cusp fractures; & (2) Seal provided by adhesive can greatly decrease, & often eliminate post-operative sensitivity. Following report summarizes CRA laboratory study of shear bond strength & sealing capability of 23 commercial adhesives used to bond 2 types of silver amalgam to tooth structure.

  12. Handling characteristics of a palladium-free gallium-based alloy compared with a high copper dental amalgam in a simulated clinical trial.

    PubMed

    Shaini, F J; Shortall, A C; Ellakwa, A E; Marquis, P M

    2001-11-01

    The aim of the current study was to compare the handling characteristics of a palladium-free gallium-based alloys (Galloy) with those of a high-copper amalgam (Permite C). The study had a particular interest in the evaluation of the direct placement delivery system used with both alloys. Ten dentists participated in the current study. Each placed two amalgam and two gallium-based alloy restorations in conventional class II cavities prepared in acrylic typodont teeth. None of the participating dentists had used the direct placement delivery system or had any previous experience with gallium-based alloy and no practice was allowed beforehand. The restorations were evaluated according to the following criteria: ease of loading the cavity (delivery system), ease of condensation, capacity to produce and sustain contact area, ease of carving, resistance to damage during removal of the matrix band, overall quality of the restoration and the available working time. Each criterion was given a score on a scale of 1-5 (1: very poor, 2: poor, 3: fair, 4: good, 5: very good). The results showed no statistically significant difference in the evaluated criteria between the two alloys (P > 0.05) except for criterion number 2 (ease of condensation, P=0.0005).

  13. [Black or white--is amalgam 'out'? Part 1. Amalgam or composite: which of these 2 materials is the most deleterious?].

    PubMed

    De Moor, Roeland; Delmé, Katleen

    2008-01-01

    Dental amalgam containing mercury has been condemned because of its toxicity and hence to be damaging of harmful to the general health. It must be clear that many sensational, confusing and misleading reports have been published. Today there is evidence that dental amalgam in the oral cavity does not harm anyone's health. For those who are condemning amalgam there an abundant number of alarming reports taking into consideration the biologic effects of resin composites: methacrylate allergy for dentists and dental technicians, the three-finger-syndrome due to contact with liquid resin, allergic reactions at the level of the airways and breathing problems caused by dust particles (esp. composite particles after polishing procedures) have been described. It can be concluded that dental amalgam is not more toxic than resin composite in light of both patients' and dental care providers' health. Recent investigations demonstrated higher than expected health risks with resin composites.

  14. Dental Stem Cell Migration on Pulp Ceiling Cavities Filled with MTA, Dentin Chips, or Bio-Oss

    PubMed Central

    Lymperi, Stefania; Taraslia, Vasiliki; Tsatsoulis, Ioannis N.; Samara, Athina; Velentzas, Athanasios D.; Agrafioti, Anastasia; Anastasiadou, Ema; Kontakiotis, Evangelos

    2015-01-01

    MTA, Bio-Oss, and dentin chips have been successfully used in endodontics. The aim of this study was to assess the adhesion and migration of dental stem cells on human pulp ceiling cavities filled with these endodontic materials in an experimental model, which mimics the clinical conditions of regenerative endodontics. Cavities were formed, by a homemade mold, on untouched third molars, filled with endodontic materials, and observed with electron microscopy. Cells were seeded on cavities' surface and their morphology and number were analysed. The phenomenon of tropism was assessed in a migration assay. All three materials demonstrated appropriate microstructures for cell attachment. Cells grew on all reagents, but they showed a differential morphology. Moreover, variations were observed when comparing cells numbers on cavity's filling versus the surrounding dentine disc. The highest number of cells was recorded on dentin chips whereas the opposite was true for Bio-Oss. This was confirmed in the migration assay where a statistically significant lower number of cells migrated towards Bio-Oss as compared to MTA and dentin chips. This study highlights that MTA and dentin chips have a greater potential compared to Bio-Oss regarding the attraction of dental stem cells and are good candidates for bioengineered pulp regeneration. PMID:26146613

  15. Amalgam ablation with the Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Wigdor, Harvey A.; Visuri, Steven R.; Walsh, Joseph T., Jr.

    1995-04-01

    Any laser that will be used by dentist to replace the dental drill (handpiece) must remove dental hard tissues safely. These lasers must also have the ability to ablate the restorative dental materials which are present in the teeth being treated. Prior to any laser being used to treat humans a thorough knowledge of the effects of the laser treatment on dental materials must be understood. Cores of dental amalgam were created and sliced into thin wafers for this experiment. Ablation efficiency and thermal changes were evaluated with and without water. It appears as if the Er:YAG laser can effectively ablate amalgam dental material with and without water. The water prevents the temperature from increasing much above baseline and does not reduce efficiency of ablation.

  16. Evaluation of Marginal Integrity of Four Bulk-Fill Dental Composite Materials: In Vitro Study

    PubMed Central

    Orłowski, Mirosław; Tarczydło, Bożena; Chałas, Renata

    2015-01-01

    Objective. The aim of the study was to compare under in vitro conditions marginal sealing of 4 different bulk-fill materials composite restorations of class II. Methods. Comparative evaluation concerned 4 composites of a bulk-fill type: SonicFill, Tetric EvoCeram Bulk Fill, Filtek Bulk Fill, and SDR. The study used 30 third molars without caries. In each tooth 4 cavities of class II were prepared. The prepared tooth samples were placed in a 1% methylene blue solution for 24 h, and after that in each restoration the depth of dye penetration along the side walls was evaluated. Results. The highest rating (score 0, no dye penetration) was achieved by 93.33% of the restorations made of the SDR material, 90% of restorations of SonicFill system, 86.66% of restorations of the composite Filtek Bulk Fill, and 73.33% of restorations of the Tetric EvoCeram Bulk Fill. Conclusion. The performed study showed that bulk-fill flowable or sonic-activated flowable composite restorations have better marginal sealing (lack of discoloration) in comparison with bulk-fill paste-like composite. PMID:25874254

  17. Characterization of dental fillings found in skulls from individuals buried in San Jeronimos Church, New Spain: historical and archaeological evidences.

    PubMed

    Mansilla, J; Romero, C; Bosch, P; Leboreiro, I; Pijoan, C

    2006-01-01

    Repair of teeth during the XIX century was often a very costly and painful procedure. During this period, restoration of teeth was a procedure limited only to those who could afford such care. In this study we analyzed teeth from a skull sample found in San Jeronimo's Church. The characterization of molar fillings was made with techniques such as X-ray fluorescence, X-ray diffraction and electron microscopy. The purpose of this investigation was to establish technical procedures for analysis, and to discuss the results within the context of the socioeconomic status of these individuals and the written descriptions of the dental practice during the XIX century.

  18. Effect of dental restorative materials on total antioxidant capacity and calcium concentration of unstimulated saliva

    PubMed Central

    Moghadam, Mona-Momeni; Garcia-Godoy, Franklin; Asatourian, Armen; Aminsobhani, Mohsen; Scarbecz, Mark; Sheibani, Nader

    2017-01-01

    Background To evaluate the effect of dental amalgam and composite restorations on total antioxidant capacity (TAC) and calcium (Ca) ion concentration of unstimulated saliva. Material and Methods Forty-eight children aged 6-10 years selected and divided into three groups of sixteen (8 males, 8 females). In group A and B, samples consisted of two class II dental composite or amalgam restorations, while in group C samples were caries-free (control group). Unstimulated saliva from all samples was collected and TAC was measured by spectrophotometry using an adaptation of 2, 2’-azino-di-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) assay. The Ca ion level was estimated by an auto- analyzer. Data were analyzed with one- and two-way ANOVA test, at a p<.05 level of significance. Results Composite samples showed significantly higher TAC and lower Ca ion levels compared to amalgam and caries-free samples (p<.05). The TAC values showed only significant difference between groups (p<.05), while the Ca ion results showed significant differences within and between groups (p<.05). Conclusions Dental composite restorations increased TAC and decreased Ca ion levels more than amalgam restorations in saliva. Gender is an effective factor in changes induced in oral cavity as females showed more emphatic reaction to dental filling materials than males. Statement of Clinical Relevance Patients who have dental restorations, especially dental composites, should pay more attention to their dental hygiene, because dental restorations can increase oxidative stress and decrease Ca ion level in saliva, which might jeopardize remineralization process of tooth structures after demineralization. Key words:Amalgam, caries, composite, saliva, total antioxidant capacity. PMID:28149467

  19. Stress Relaxation of High-Copper Amalgam Alloys,

    DTIC Science & Technology

    1978-03-10

    Unlimited ~~~ 17. DISTRIBUTION STA ~~EMENT (of th. ab.traci .nt. r.d In Block 20. i di f ferent from Report) 1$. SUPPLEMENTARY NOTES IS. KEY WORDS...Contlnu• on r.v.,a. aid. SI n.c...ay aid Id.ntlfy by block niaib. r) Amalgam alloys; high—copper amalgam alloys; viscoelastic properties and stress...relaxation. 20. ABSTRACT (Ge.~~~j . ai r, ,.,.. .i~~ II ne.ma y d Sd.nsSfr by block n~~~)5 tress relaxation of sevenhigh— copper dental amalgam alloys was

  20. 75 FR 33315 - Dental Products Panel of the Medical Devices Advisory Committee; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-11

    ... received by FDA concerning the final rule on the classification of dental amalgam, which published in the... adequacy of the risk assessment performed by FDA in classifying dental amalgam in light of a new report...

  1. Evaluation of simulation learning materials use to fill the gap in Japanese dental English education.

    PubMed

    Seki, Naoko; Moross, Janelle; Sunaga, Masayo; Hobo, Koki; Miyoshi, Tomoe; Nitta, Hiroshi; Kinoshita, Atsuhiro; Morio, Ikuko

    2016-01-01

    Even though English is most frequently the common language when the patient's native language differs from that of a dentist, the opportunities for Japanese undergraduate dental students to learn dental English are now quite limited. The purposes of our study were to investigate: the effectiveness and feasibility of the computer-assisted simulation materials as one solution strategy for dental English education in Japan, and the needs and demands for dental English from the learners' side. Interactive simulation materials for medical interviews in English and clinical cases which were translated to English, were delivered via Learning Management System (LMS) to nineteen trainee residents of dentistry (residents). Evaluation for the materials, learners' knowledge and interests in the contents, and ease of operation were obtained by post-questionnaire (response rates were 100% and 95%, respectively). Both questionnaire-surveys received positive feedback toward the materials, yet 47% answered that they lacked the level of knowledge about contents of the medical interview in English. Results were sufficient to suggest that the residents would like to have the opportunity to study or practice medical interview in English, or English related to dentistry, and that the simulation materials could be one of the solution strategies for opportunity provision.

  2. Managing the phase-down of amalgam: Part I. Educational and training issues.

    PubMed

    Lynch, C D; Wilson, N H F

    2013-08-01

    Following the recently agreed Minamata Convention, a phase-down in the use of dental amalgam will become a priority for the profession. With a lead-in period of a number of years, important changes in the mind-set of the profession are required to ensure that patient safety is not compromised. Posterior composites have been a viable, and in many cases preferable, alternative to amalgam for many years. However, notwithstanding considerable developments in dental school teaching on the application and placement of posterior composites, growing evidence to support the use of composites in the restoration of posterior teeth and advances in composite systems, many practitioners remain reluctant to place composite rather than amalgam. This paper considers the present and future use of posterior composites and highlights ways in which dental school teaching and continuing professional development (CPD) may contribute to the successful phase-down, and now inevitable discontinuation, in the use of dental amalgam.

  3. The Post-Amalgam Era: Norwegian Dentists' Experiences with Composite Resins and Repair of Defective Amalgam Restorations.

    PubMed

    Kopperud, Simen E; Staxrud, Frode; Espelid, Ivar; Tveit, Anne Bjørg

    2016-04-22

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists' satisfaction with alternative restorative materials and to explore dentists' treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%), followed by restoration fractures (25.1%). Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p < 0.01), employees in the Public Dental Service (PDS) (p < 0.01) and dentists working in counties with low dentist density (p = 0.03). There was a tendency towards choosing minimally invasive treatment among dentists who also avoided operative treatment of early approximal lesions (p < 0.01). Norwegian dentists showed positive attitudes towards composite as a restorative material. Most dentists chose minimally- or medium invasive approaches when restoring fractured amalgam restorations.

  4. The Post-Amalgam Era: Norwegian Dentists’ Experiences with Composite Resins and Repair of Defective Amalgam Restorations

    PubMed Central

    Kopperud, Simen E.; Staxrud, Frode; Espelid, Ivar; Tveit, Anne Bjørg

    2016-01-01

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists’ satisfaction with alternative restorative materials and to explore dentists’ treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%), followed by restoration fractures (25.1%). Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p < 0.01), employees in the Public Dental Service (PDS) (p < 0.01) and dentists working in counties with low dentist density (p = 0.03). There was a tendency towards choosing minimally invasive treatment among dentists who also avoided operative treatment of early approximal lesions (p < 0.01). Norwegian dentists showed positive attitudes towards composite as a restorative material. Most dentists chose minimally- or medium invasive approaches when restoring fractured amalgam restorations. PMID:27110804

  5. An in vitro microleakage study of different filling materials using dye penetration method.

    PubMed

    Bashar, A K M; Alam, M S; Hussain, M A; Islam, M M; Hossain, M M

    2006-04-01

    In the present study, the marginal integrity of different filling materials was evaluated in invitro. Furthermore, the effect of manipulation technique on their microleakage was also investigated. A total of sixty standard prepared class V cavities were filled with glass ionomer cement (both auto-cured and light-cured), light cured packable variety composite resin pretreated with echant and bonding agent and dental amalgam (both mechanically and conventional hand mixed) with or without pretreatment by cavity varnish. Cavities were then subjected to microleakage test following thermocycling. Statistical analysis was performed by One way ANOVA and Sheffe's multiple comparison tests. The results showed that mechanically mixed Silver Amalgam pretreated with cavity varnish showed the least microleakage, whereas, autocured glass ionomer showed highest marginal leakage. Light-cured packable composite was superior in resisting microleakage than both types of glass ionomer but was inferior to dental amalgam in the same respect. From this study, it can be concluded that composite resin can be used to fill class V cavities for esthetic reason but their properties should be improved.

  6. Effect of composite/amalgam thickness on fracture resistance of maxillary premolar teeth, restored with combined amalgam-composite restorations

    PubMed Central

    Firouzmandi, Maryam; Doozandeh, Maryam; Abbasi, Sanaz

    2016-01-01

    Background Combined amalgam-composite restorations have been used through many years to benefit from the advantages of both dental amalgam and composite resin. Two variations have been mentioned for this technique, this study investigated the fracture resistance of maxillary premolar teeth with extended mesio-occluso-distal (MOD) cavities, restored with the two variations of combined amalgam-composite restorations. Material and Methods Sixty intact extracted premolar teeth were randomly divided into 6 groups (G1-G6) of 10 teeth. G1; consisted of intact teeth and G2; consisted of teeth with MOD preparations were assigned as the positive and negative control groups respectively. Other experimental groups after MOD preparations were as follows: G3, amalgam restoration; G4, composite restoration; G5 combined amalgam-composite restoration with amalgam placement only on 1mm of the gingival floor of the proximal boxes; G6, combined amalgam-composite restoration with amalgam placement to the height of contact area of the proximal surface of the tooth. Fracture strength of the specimens was measured and the data were analyzed using one-way analysis of variance (ANOVA). The level of significance was P<0.05. Fracture mode of the specimens was also recorded. Results G1 had the highest value of fracture resistance (1736.90 N). G2 and G3 had the lowest fracture resistance (775.70 N and 874.70 N, respectively). The difference between G 4, 5 and 6 was not statistically significant. However, G4, G5 and G6 showed significantly higher resistance to fracture compared to G2 and G3. Fracture modes were favorable in all of the study groups except in G6. Conclusions Fracture resistance of the premolars restored with the two variations of combined amalgam-composite restoration was similar to that achieved with composite restoration alone and more than that of amalgam restoration alone. It can be concluded that the thickness of amalgam in combined amalgam-composite restorations did not

  7. Dental material artifacts on MR images.

    PubMed

    Hinshaw, D B; Holshouser, B A; Engstrom, H I; Tjan, A H; Christiansen, E L; Catelli, W F

    1988-03-01

    Magnetic resonance (MR) imaging of the head and neck is becoming an important aid in evaluating pathologic conditions of the brain, midface, and pharynx. Certain dental materials cause artifacts during MR imaging of the lower midface. These artifacts can obscure the normal anatomy. This study describes the degree of artifact production caused by various materials commonly used in dental restorations. Of the materials tested, those causing artifacts were made of stainless steel, such as orthodontic bands used for braces, and pins or posts that are commonly drilled into teeth to provide structure or stability before filling. Materials used as temporary or permanent fillings or crowns--such as amalgam, gold alloy, aluminum, microfilled resin, and polyvinyl acrylics--did not cause artifacts in the images.

  8. Release and toxicity of dental resin composite.

    PubMed

    Gupta, Saurabh K; Saxena, Payal; Pant, Vandana A; Pant, Aditya B

    2012-09-01

    Dental resin composite that are tooth-colored materials have been considered as possible substitutes to mercury-containing silver amalgam filling. Despite the fact that dental resin composites have improved their physico-chemical properties, the concern for its intrinsic toxicity remains high. Some components of restorative composite resins are released in the oral environment initially during polymerization reaction and later due to degradation of the material. In vitro and in vivo studies have clearly identified that these components of restorative composite resins are toxic. But there is a large gap between the results published by research laboratories and clinical reports. The objective of this manuscript was to review the literature on release phenomenon as well as in vitro and in vivo toxicity of dental resin composite. Interpretation made from the recent data was also outlined.

  9. Release and toxicity of dental resin composite

    PubMed Central

    Gupta, Saurabh K.; Saxena, Payal; Pant, Vandana A.; Pant, Aditya B.

    2012-01-01

    Dental resin composite that are tooth-colored materials have been considered as possible substitutes to mercury-containing silver amalgam filling. Despite the fact that dental resin composites have improved their physico-chemical properties, the concern for its intrinsic toxicity remains high. Some components of restorative composite resins are released in the oral environment initially during polymerization reaction and later due to degradation of the material. In vitro and in vivo studies have clearly identified that these components of restorative composite resins are toxic. But there is a large gap between the results published by research laboratories and clinical reports. The objective of this manuscript was to review the literature on release phenomenon as well as in vitro and in vivo toxicity of dental resin composite. Interpretation made from the recent data was also outlined. PMID:23293458

  10. Minor changes in serum levels of cytokines after removal of amalgam restorations.

    PubMed

    Björkman, Lars; Brokstad, Karl A; Moen, Ketil; Jonsson, Roland

    2012-06-01

    Dental amalgam restorations release mercury and silver which is absorbed and distributed in the body. Animal studies have shown that both elements may interfere with the host by activation of the immune system in genetically susceptible strains at exposure levels relevant to those from dental amalgam restorations. The aim of this study was to test the hypothesis of no change over time in concentrations of a number of immune mediators in serum after removal of all dental amalgam restorations in patients with health complaints attributed to their amalgam restorations and compare with a healthy reference group. Twenty patients previously examined at a specialty unit for health complaints attributed to dental materials were included in a clinical trial and had all amalgam restorations replaced with other dental restorative materials. Serum samples were collected before amalgam removal and 3 and 12 months after the removal was finished. Twenty blood donors matched for age and gender were used as comparison group. A fluorescent bead-based (Luminex) immunoassay kit was used to measure cytokines, chemokines and growth factors in serum. At baseline, the patient group had slightly higher values for GM-CSF, IL-6, IL-2R, IFN-alpha, IL-7, and IL-12p40/p70 compared with the reference group. After amalgam removal a decrease towards the median value of the reference group was found for GM-CSF, IL-8, and IL-7. In conclusion, removal of all dental amalgam restorations and replacement with other dental restorative materials was associated with decreased concentrations of Th1-type proinflammatory markers in serum.

  11. Interface corrosion in amalgam-to-amalgam and amalgam-to-nonprecious metal crown couplings.

    PubMed

    Schimelmitz, H; Bapna, M S; Punwani, I; Ashrafi, S H; Anderson, A W

    1986-02-01

    This study examined the contact surface area in the coupling of a class II amalgam restoration with another class II amalgam restoration or with a stainless steel or nickel-chrome crown in 1% NaCl solution. The characterization of interfaces was carried out by using SEM and EDX microanalysis. The results indicate that the coupling of an amalgam-stainless steel crown and an amalgam-inconel crown in NaCl solution forms a deposit on the crown surfaces. This deposit contains all the constituents of corrodible phases of amalgam, including Zn. If amalgam restorations in adjoining teeth are contemplated, non-Zn-containing amalgam alloys of the same composition should be considered.

  12. Mercury Amalgam Diffusion in Human Teeth Probed Using Femtosecond LIBS.

    PubMed

    Bello, Liciane Toledo; da Ana, Patricia Aparecida; Santos, Dário; Krug, Francisco José; Zezell, Denise Maria; Vieira, Nilson Dias; Samad, Ricardo Elgul

    2017-01-01

    In this work the diffusion of mercury and other elements from amalgam tooth restorations through the surrounding dental tissue (dentin) was evaluated using femtosecond laser-induced breakdown spectroscopy (fs-LIBS). To achieve this, seven deciduous and eight permanent extracted human molar teeth with occlusal amalgam restorations were half-sectioned and analyzed using pulses from a femtosecond laser. The measurements were performed from the amalgam restoration along the amalgam/dentin interface to the apical direction. It was possible to observe the presence of metallic elements (silver, mercury, copper and tin) emission lines, as well as dental constituent ones, providing fingerprints of each material and comparable data for checking the consistence of the results. It was also shown that the elements penetration depth values in each tooth are usually similar and consistent, for both deciduous and permanent teeth, indicating that all the metals diffuse into the dentin by the same mechanism. We propose that this diffusion mechanism is mainly through liquid dragging inside the dentin tubules. The mercury diffused further in permanent teeth than in deciduous teeth, probably due to the longer diffusion times due to the age of the restorations. It was possible to conclude that the proposed femtosecond-LIBS system can detect the presence of metals in the dental tissue, among the tooth constituent elements, and map the distribution of endogenous and exogenous chemical elements, with a spatial resolution that can be brought under 100 µm.

  13. Mercury release of amalgams with various silver contents after exposure to bleaching agent

    PubMed Central

    Bahari, Mahmoud; Alizadeh Oskoee, Parnian; Savadi Oskoee, Siavash; Pouralibaba, Firoz; Morsali Ahari, Ali

    2016-01-01

    Background. Since it is possible for carbamide peroxide (CP) bleaching agent to contact old amalgam restorations, the present in vitro study evaluated the amount of dissolved mercury released from amalgam restorations with various percent-ages of silver content subsequent to the use of 15% CP. Methods. Thirty ANA 2000 amalgam disks with 43.1% silver content and thirty ANA 70 amalgam disks with 69.3% silver content were prepared. In each group, 15 samples were randomly placed in glass tubes containing 15% CP (as experimental groups) and the remaining 15 samples were placed in buffered phosphate solution (as control groups) with the same 3-mL volume for 48 hours. Subsequently, the amount of mercury dissolved in each test tube was measured using Mercury Analyzing System (Cold Vapor Atomic Absorption, MASLO, Shimadzu, Japan). Data was analyzed with two-way ANOVA and a post hoc Tukey test. (α = 0.05). Results. The amount of mercury released after exposure to CP was significantly higher than that released after exposure to buffered phosphate (P < 0.001). In addition, the amount of mercury released from dental amalgam with a silver content of 43% was significantly higher than that released from dental amalgam with a silver content of 69% (P < 0.001). Conclusion. The amount of mercury release is inversely proportional to the silver content of dental amalgam. PMID:27429729

  14. Comparison of wear and clinical performance between amalgam, composite and open sandwich restorations: 2-year results.

    PubMed

    Sachdeo, A; Gray, Gordon B; Sulieman, M A; Jagger, Daryll C

    2004-03-01

    There has been some disquiet over the use of mercury containing restorative materials. The most commonly used alternative is composite resin but this has the potential disadvantage associated with wear and marginal leakage, which in turn, has proven to result in secondary caries and sensitivity. To overcome the shortcomings of a directly placed composite restoration, the glass-ionomer/composite open sandwich technique was introduced followed by the subsequent introduction of compomer systems. The aims of this study were to evaluate the wear and clinical performance of a control group of amalgam restorations compared with that of a group of posterior composite resin restorations fillings and a group of compomer/composite open sandwich restorations placed by a single general dental practitioner. The duration of the study was 2 years. One hundred and thirty three (71.4%) patients were successfully recalled and the wear and clinical performance of each restoration after 6, 12 and 24 months was measured, indirectly. There was no statistically significant difference recorded between the groups at 6 months or 1 year (p > 0.05). However, at the end of the 2-year study, there was a significantly lower rate of wear recorded for the control amalgam restorations compared with other two groups (p = 0.033). There was no statistically significant difference in wear recorded between the two groups of tooth-coloured restorations (p > 0.05). With regards to clinical performance of the restorations, occlusal and proximal contacts in each group of restoration remained satisfactory throughout the study.

  15. VIEW, LOOKING SOUTHWEST OF GOLD AMALGAMATION ROOM, SHOWING AMALGAMATION BARREL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW, LOOKING SOUTHWEST OF GOLD AMALGAMATION ROOM, SHOWING AMALGAMATION BARREL AT CENTER FOREGROUND, BULLION FURNACE IN LARGE HOOD BEHIND IT, AND GOLD RETORT IN BACKGROUND HOOD. NOTE OVERHEAD MONORAIL FOR MATERIALS HANDLING. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  16. 21 CFR 872.3700 - Dental mercury.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental mercury. 872.3700 Section 872.3700 Food and... DENTAL DEVICES Prosthetic Devices § 872.3700 Dental mercury. (a) Identification. Dental mercury is a device composed of mercury intended for use as a component of amalgam alloy in the restoration of...

  17. Use of self-curing composite resins to facilitate amalgam repair.

    PubMed

    Lacy, A M; Rupprecht, R; Watanabe, L

    1992-01-01

    Resin cements, which have been shown to adhere to various metal alloys, were investigated as possible repair adhesives for dental amalgam. Test bars of repaired amalgam, formed by condensing new alloy against previously set alloy with or without the use of "adhesive" resins, were subjected to three-point bending measurements of transverse fracture strength. The results indicated that application of adhesive resin did not improve the breaking strength of the repaired specimens from that of specimens prepared without the use of such resins. The breaking strength of all repaired specimens was approximately 15% of the transverse fracture strength of the original intact amalgam bars. Scanning electron microscopy revealed that there was an intermixing of fresh amalgam and unset interfacial resin, which led to mechanical bonding of these materials, but there was no evidence of adhesion of the resin to the previously set amalgam.

  18. In vitro comparison of the shear bond strength of amalgam to tooth structure using two bonding agents--lutting glass ionomer and 4-META.

    PubMed

    Sheela, K; Sudeep, P T; Hegde, V; Francis, R F; Bhat, K S; Sundeep, P T

    1998-01-01

    Bonding dental amalgam to tooth structure using 4-META has become an accepted clinical procedure. Glass ionomer cements possess the ability to bind to tooth structure as well as to the components of dental amalgam. The present in vitro study evaluates the shear bond strength of amalgam to tooth structure using luting glass ionomer as a bond mediating agent, and compares with that obtained using 4-META. Results indicate that it is possible to bond amalgam to tooth structure using a thin layer of glass ionomer cement. The shear bond strength of glass ionomer cement mediated bond is significant and may be adequate for clinical application.

  19. Effects of Clinical Training and Case Difficulty on the Radiographic Quality of Root Canal Fillings Performed by Dental Students in Saudi Arabia

    PubMed Central

    Alsulaimani, Reem Siraj; Al-Manei, Kholod Khalil; A. Alsubait, Sara; AlAqeely, Razan Shafik; A. M. Al-Shehri, Sharifa; M. Al-Madi, Ebtissam

    2015-01-01

    Introduction: The aim of this study was to evaluate the effects of training duration and case difficulty on the radiographic quality of root canal fillings performed by dental students in Saudi Arabia. Methods and Materials: A longitudinal cohort study was conducted at King Saud University. Root canal treatments performed by 55 dental students from 2012-2014 were included in the study. Each student treated at least five teeth during the first year of clinical endodontic training and another five teeth during the second year. Case difficulty was assessed based on tooth position in the dental arch and preoperative conditions. The radiographic quality of the root canal filling was evaluated by two endodontists blinded to treatment completion date. The evaluation criteria were adequate obturation, presence of mishaps and preparation taper. The data were statistically analysed using univariate and multivariate logistic regression analyses; and the level of significance was set at 0.05. Results: Inadequate obturation and mishaps were significantly less prevalent in teeth treated after 2 years of clinical training. The odds ratios for inadequate obturation and mishaps increased significantly as tooth position moved posteriorly. Inadequate obturation and more mishaps were significantly more prevalent in teeth with preoperative conditions. Preparation taper was not significantly affected by training duration or case difficulty. Conclusion: The quality of root canal fillings performed by Saudi students was adversely affected by case difficulty. The radiographic quality of root canal fillings improved significantly after 2 years of clinical training. Preparation taper outcome is likely dependent on the preparation technique and instrument taper. PMID:26523143

  20. Forensic or archaeological issue: is chemical analysis of dental restorations helpful in assessing time since death and identification of skeletonized human remains?

    PubMed

    Zelic, Ksenija; Djonic, Danijela; Neskovic, Olivera; Stoiljkovic, Milovan; Nikolic, Slobodan; Zivkovic, Vladimir; Djuric, Marija

    2013-09-01

    In 2011, small mass grave with completely skeletonized remains was discovered in Belgrade suburb. An eyewitness claimed that skeletons belonged to German soldiers killed in WWII. Anthropologists were engaged to investigate whether the skeletal remains correspond to the indicated German group or represent more recent case requiring court trial. Numerous dental restorations were noticed. Owing to the fact that different dental materials were used in dental practice at certain times, the aim of this study was to explore whether analysis of dental restorations could help in identification and estimation of time since death. Inductively coupled plasma optical emission spectrometry revealed that dental fillings corresponded to copper amalgam, conventional silver amalgam, silicophosphate cement, and zinc phosphate cement. Chemical results combined with anthropological and historical facts suggest that the individuals lived before the 1960s in country with well-developed dental service at that time. Therefore, chemical analysis of dental fillings was useful to distinguish between skeletal remains that are too old to be of forensic interest and the remains relevant to legal investigations.

  1. Development and Validation of a Prototype Vacuum Sensing Unit for the DD2011 Chairside Amalgam Separators

    DTIC Science & Technology

    2015-10-30

    during placement and removal of amalgam restorations can contribute to mercury pollution in waterways. Chairside amalgam separators in dental...1L/min. A liter of water evacuated within 1 min, 1.5 min, and greater than 2 min were categorized as normal, warning, and critical states... water through the system. The time that flushing began and ended was recorded. The high vacuum evacuation device valve remained open until all

  2. Dependence of kinetic variables in the short-term release of Hg2+, Cu2+ and Zn2+ ions into synthetic saliva from an high-copper dental amalgam.

    PubMed

    Campus, Guglielmo; Garcia-Godoy, Franklin; Gaspa, Leonardo; Panzanelli, Angelo; Piu, Paola C; Micera, Giovanni; Lugliè, Pierfranca; Sanna, Gavino

    2007-08-01

    The short term (up to 14 days after restoration) release of selected ions (i.e., Hg(2+), Cu(2+) and Zn(2+)) from Dispersalloy into artificial saliva has been evaluated in regards to the nature of the saliva (Fusayama and McCarty and Shklar's solutions), the amount of amalgam, the time of contact and the periodical renewal (every 48 h interval) of artificial saliva. The evaluation of the ionic fraction of such metals has been accomplished by using anodic stripping methods (i.e., Differential Pulse Anodic Stripping Voltammetry, DPASV) with a 7 microm graphite disk microelectrode as a working electrode. Data obtained in this work are almost unprecedented in the literature due the fact that such analytical method exclude metals in non-ionic forms (e.g., metals or organometallic compounds). The high concentrations measured in every experimental condition confirm the concern for the short-term release of metals from amalgam into saliva.

  3. [Dental care, dental diseases and dentistry in antiquity].

    PubMed

    Józsa, László

    2009-01-01

    Numerous written relicts, belletristic works (poems of Martial, Juvenal, Ovid etc.) indicate that oral hygiene and its tools (toothbrush, toothpick, use of tooth pastes and tooth-powder) were used long before our times. Already ancient people started to remove, file, dye and inlay teeth. The teeth were dyed red, green or black in Egypt, red or brown (with henna or betel) in India, white by Romans. The teeth decoration has a long but forgotten history. The most skillful and artistic work was done by the Maya's between 900 BC and 1500 AD. The modification of contours (more than fifty forms) of the incisors were practiced also in Mesoamerica. Dentistry was surely practiced in ancient Egypt, India, China, Greece and Rome, while odontology and especially suitable dental appliances arose only by Etruscan. Dental prosthesis, including bridges and simple retention bands were invented by the Etruscans 2500 years ago. These Etruscan bridges were worn mostly by females, suggesting that cosmetics was the principal dental concern. Some,--if not all--of the Roman and other prostheses have been purely ornamental. Orthodontic appliances are also Etruscan invention. The holes caused by caries were filled with garlic, incense, caraway seed in Egypt, with wood or lead in Rome, and with "silver-paste" (amalgam) in ancient China. The toothache was cured with poppy-tee, or hashish and nightshade plants (Solanaceae) in Egypt, Greece, Roman Empire while with coca (Erythroxylon coca) in South-America.

  4. The use of amalgam in pediatric dentistry: new insights and reappraising the tradition.

    PubMed

    Fuks, Anna B

    2015-01-01

    The debate on amalgam led to its being phased out in some countries. Results of clinical trials report failure rates of amalgams ranging from 12 percent to over 70 percent. Treatment of caries should meet the needs of each particular patient, based on his/her caries risk. In general, for small occlusal lesions, a conservative preventive resin restoration would be more appropriate than the classic Class I amalgam preparation. For proximal lesions, amalgam would be indicated for two-surface Class II preparations that do not extend beyond the line angles of primary teeth. This recommendation might not be appropriate for high-risk patients or restoring primary first molars in children four years old and younger where stainless steel crowns have demonstrated better longevity. Currently, amalgam demonstrates the best clinical success for Class II restorations that extend beyond the proximal line angles of permanent molars. The need to reduce the use of amalgam as a mercury-containing material is inevitable when aiming to reduce environmental contamination. It is important always to praise prevention and constantly search for biologically safe materials regarding health, clinical work, and environment. The purpose of this report was to summarize several factors that affect the effectiveness, advantages, and disadvantages of using dental amalgam in primary teeth.

  5. Evaluation of corrosion degradation of amalgams by immersion and fracture test.

    PubMed

    Horasawa, Noriko; Takahashi, Shigeo; Marek, Miroslav

    2003-12-01

    In this study an immersion and fracture test was used to evaluate the susceptibility of dental amalgams to degradation of their mechanical strength by corrosion. Specimens of each of the six types of high-copper amalgams and one type of low-copper amalgam were prepared and tested. Cylindrical specimens were grooved using a diamond cutoff blade and immersed in 1% NaCl to which H2O2 was added to increase the oxidation power. After two weeks of exposure the specimens and controls were fractured and the loss of strength was calculated. Two amalgams showed a significant loss of strength. The test procedure is relatively simple and does not require sophisticated electrochemical or analytical instrumentation. A higher resolution power might be achieved by increasing the severity of corrosion or the number of replicate tests.

  6. [Amalgam, composite and compomer: microbiological study].

    PubMed

    Zogheib, C M; Hardan, L; Khoury, C Kassis; Naaman, N Bou Abboud

    2012-03-01

    Restorative materials have different consequences on the periodontium. The surface of these materials may influence gingival health and cause in some instances gingival inflammation. The purpose of this study was to investigate and compare, in a healthy periodontium, intracrevicular plaque bacteria (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis and Treponema denticola), at day 0 and at 6 months, around subgingivally located amalgam, composite and compomer fillings. All the tests were negative (less than 0.1% of the sum of 103 cells), since none of the investigated pathogens were detected. It has been concluded that the material used does not have direct effect on the bacteria species developed around the restorations at this short time period.

  7. Bond strength comparison of amalgam repair protocols using resin composite in situations with and without dentin exposure.

    PubMed

    Ozcan, Mutlu; Schoonbeek, Geert; Gökçe, Bülent; Cömlekoglu, Erhan; Dündar, Mine

    2010-01-01

    The replacement of defective amalgam restorations leads to loss of tooth material and weakens the tooth, creating an increased risk of cusp fracture. The repair of such defects is a minimal intervention technique. The current study compared the repair bond strengths of a resin composite to amalgam and an amalgam-dentin complex after various surface conditioning methods. The specimens (N = 50) consisted of sound human canines with cylindrical preparations (diameter: 2.3 mm, depth: 3 mm) with amalgam-dentin complex (N = 30, n = 10/per group) and two groups with amalgam only (N = 20, n = 10/per group). The teeth were embedded in auto-polymerized polymethylmethacrylate (PMMA). The preparations were filled with non-Gamma 2 amalgam. The enamel was removed to expose dentin. The specimens with the amalgam-dentin complex were randomly assigned to one of the following conditioning methods: Group 1: Silicacoating amalgam, etching dentin, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both; Group 2: Etching dentin, silicacoating amalgam, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both and Group 3: Etching dentin, primer/bonding on dentin, opaquer, resin composite. The specimens with only amalgam were assigned to one of the following conditioning methods: Group 4: Silicacoating, silane application, opaquer, resin composite and Group 5: Opaquer, resin composite. For the two control groups, where no dentin was involved (Groups 4 and 5), bonding was achieved only on amalgam and Group 5 had no conditioning. The specimens were kept in water at 37 degrees C for five weeks before bond strength (MPa +/- SD) testing (Universal Testing Machine). After debonding, the failure types were analyzed. The results were significantly affected by the surface conditioning method (ANOVA). Only dentin conditioning (Group 3) showed the highest bond strength (39.9 +/- 14). The unconditioned control

  8. Effect of restoration size on fracture resistance of bonded amalgam restorations.

    PubMed

    Lindemuth, J S; Hagge, M S; Broome, J S

    2000-01-01

    The purpose of this study was to determine the effect of restoration size on the fracture strength of amalgam restorations bonded with Amalgambond Plus (with HPA). Research has shown that this adhesive is dispersed throughout the unset amalgam during condensation and that a decrease in diametral tensile strength, proportional to the amount of adhesive incorporated into the unset amalgam, has resulted. Smaller cavity preparations have a higher ratio of surface area to volume than do larger preparations, and it was anticipated that a proportionately greater amount of adhesive would be incorporated into smaller amalgam restorations. Sixty extracted human molars were divided into four groups of 15 teeth and mounted in tray acrylic-filled PVC cylinders. Shallow approximo-occlusal channels were prepared in two groups. One group was restored with Amalgambond Plus and Tytin amalgam, the other with just Tytin amalgam. Larger proximo-occlusal preparations were made in the remaining two groups, then restored in the same fashion. Samples were stored in 37 degrees C for at least 24 hours, then thermocycled from 5-55 degrees C 1000 times with a one-minute dwell time. Specimens were mounted in a Universal Testing Machine, and a chisel was applied to the restorations in compression mode at a crosshead speed of 5.0 mm/minute until bulk fracture of the amalgam occurred. The results indicated no difference in bulk fracture strengths between large amalgam restorations restored with and without Amalgambond Plus. However, small amalgam restorations restored with Amalgambond Plus exhibited significantly greater (p < 0.025) bulk fracture strengths than small amalgam restorations restored without use of the adhesive.

  9. Lichenoid reaction associated with silver amalgam restoration in a Bombay blood group patient: A case report.

    PubMed

    Pawar, Rohini Rangarao; Mattigatti, Sudha S; Mahaparale, Rushikesh R; Kamble, Amit P

    2016-01-01

    The pathogenic relationship between the oral lichenoid reaction (OLR) and dental restorative materials has been confirmed many times. An OLR affecting oral mucosa in direct contact with an amalgam restoration represents a delayed, type IV, cell mediated immune response to mercury or one of the other constituents of the dental amalgam. Bombay blood group patients are more prone to this. A case of bilateral OLR is presented, which is present in relation to amalgam restoration. The lesion healed up after the replacement of restorations with an intermediate restorative material. The clinician should be aware of all the possible pathological etiologies of white lesions. If there is any doubt about the nature or management of a usual oral lesion, a referral to an appropriate specialist is mandatory.

  10. Current Teaching of Proximal Retention Grooves for Class II Amalgam Preparations.

    ERIC Educational Resources Information Center

    Moore, David L.

    1992-01-01

    A survey gathered information on methods of class II amalgam preparation taught in 59 dental schools. Focus was on the teaching and testing of proximal retention groove use, stated rationale for placing retention grooves, and the relationship of the instruction to board criteria for cavity preparation. (MSE)

  11. Correlation of gingival thickness with gingival width, probing depth, and papillary fill in maxillary anterior teeth in students of a dental college in Navi Mumbai

    PubMed Central

    Singh, Jyotsna; Rathod, Varsha J.; Rao, Prajakta R.; Patil, Aardra A.; Langade, Deepak G.; Singh, Roshan K.

    2016-01-01

    Context: The gingival biotype is of utmost importance for esthetics and biologic function. Anatomical characteristic of periodontium such as gingival thickness (GT), width of keratinized gingiva, and alveolar bone morphology will determine the behavior of periodontium when subjected to physical, chemical, or bacterial insult or during therapeutic procedure. Aims: The aim of this study was to correlate the GT with gingival width (GW), probing depth (PD), and papillary fill (PF) in relation to maxillary anterior region. Settings and Design: Undergraduate dental students and interns from a dental college in Navi Mumbai were enrolled in the study according to the inclusion criteria. Six teeth per subject were assessed; a total of 2178 maxillary anterior teeth were examined. Subjects and Methods: Subjects were examined clinically for GT, width of keratinized gingiva, pocket depth, and interdental PF. The data obtained was tabulated and subjected to statistical analysis. Statistical Analysis Used: Spearman's correlation analysis test was performed to find the correlation of GT with GW, PD, and PF. Results: Positive correlation was found between GT and GW (r = 0.241). No significant correlation could be found between GT and PD; and between GT and PF. Conclusions: The present study confirmed a positive correlation between GT and GW. A weak negative correlation was found between GT and PD. PMID:27994424

  12. A grave matter--dental findings of people buried in the 19th and 20th centuries.

    PubMed

    van Wyk, C W; Theunissen, F; Phillips, V M

    1990-12-01

    The exhumed remains of 181 people, buried during the period 1848-1984 were examined. Because of the carelessness of exhumations, only 125 yielded sufficient information to compare the condition of skulls and jaws with the period in the grave, while 63 yielded information about the teeth. No correlation could be shown between the condition of the skulls and jaws and the period interred, but it was found that the better preserved remains belonged to younger people. Dental findings included the presence of healthy and decayed teeth, gold foil restorations, gold and porcelain inlays, amalgam and silicate fillings, and vulcanite and acrylic dentures. Amalgam restorations were present in people buried from 1875 (114 years ago) and vulcanite dentures from 1882 (107 years ago). The characteristics of the earliest amalgam restorations showed that they could have been placed before 1850. Findings of this study indicate that: (a) one cannot on the appearance of exhumed remains estimate the burial period, (b) dental features were well preserved and can be used for dental identification if antimortem data are available, (c) advanced dentistry could have been practised in South Africa during the last century, and (d) recovery of human skeletal remains from old cemeteries should be undertaken with care to preserve as much information as possible. A plea is made for closer co-operation between developers of old graveyard sites and scientists in order to preserve as much information as possible.

  13. Potentiometric stripping analysis of zinc and copper in human teeth and dental materials.

    PubMed

    Kalicanin, Biljana M; Nikolić, Ruzica S

    2008-01-01

    Potentiometric stripping analysis (PSA) with oxygen as the oxidant has been used to determine soluble zinc and copper levels in exfoliated human teeth (all of which required extraction for orthodontic reasons) and commercial dental materials. The soluble zinc and copper contents of teeth were slightly below the zinc and copper contents in whole teeth reported by other researchers, except in the case of tooth with removed amalgam filling. Soluble zinc and copper concentrations of the dental materials and metal ceramic crowns were 0.50-6.30, and of 2.00-4.30 microg/g, respectively. The results of this work suggest that PSA may be a good method for zinc and copper leaching studies during the investigation of dental prosthetic materials' biocompatibility. Corrosive action of acidic media as evidenced by SEM micrographs caused the leaching of metal ions from teeth.

  14. Effect of rubber dam on mercury exposure during amalgam removal.

    PubMed

    Kremers, L; Halbach, S; Willruth, H; Mehl, A; Welzl, G; Wack, F X; Hickel, R; Greim, H

    1999-06-01

    It was the aim of this investigation to treat 20 volunteers with maximally 5 amalgam fillings by the same comprehensive protocol in which all removals with (n = 8) and without (n = 12) rubber dam had been performed within a few months. Nine amalgam-related parameters indicated a close matching of both groups before removal. In the group without rubber dam, mercury (Hg) levels in plasma increased significantly above preremoval values at days 1 and 3 after removal; they decreased significantly below preremoval values at day 30 in the rubber-dam group and at day 100 in both groups. Excretion rates did not increase significantly in either group, but decreased significantly at day 100 in the protected group. Peak plasma-Hg was 0.6 ng/mL on average at day one and decreased with halftimes of 3 and 43 d in subjects protected by rubber dam. The results indicated that concentrations of total mercury in plasma responded rapidly to changes in the amalgam status and reflected the actual absorption most reliably. Notably, plasma-Hg levels were sensitive enough to detect a transient attenuation of the additional exposure by using rubber dam during the removal of only a few fillings. However, being small in magnitude and lasting 100 d at best, the rubber-dam effect had minor toxicological relevance.

  15. Bonding of adhesive resin luting agents to metal and amalgam.

    PubMed

    Osman, Saad A; McCabe, John F; Walls, Angus W G

    2008-12-01

    The shear bond strength of three adhesives, Panavia 21, Superbond, All Bond C&B Cement, and a dual cure resin (Variolink), to Ni-Cr-Be (Rexillium III), Midigold (Type III gold) and Amalgam (Sybraloy) were determined. Fifteen samples were prepared using 800 grit abrasive papers for Ni-Cr and Midi-Gold, and 100 grit papers for amalgam. Ni-Cr-Be and Midi-Gold samples were sandblasted for 30 s and steam cleaned for 10 s. The adhesives were bonded to the samples using gelatine capsules and were matured for 24 h in water at 37 degrees C. The samples were debonded in shear using an Instron at a cross-head speed of 1 mm/min. The data was analysed using ANOVA and a Tukey test. The bond strength of Superbond to both metal alloys was significantly higher (P<0.05) than any of the materials tested, with the exception Panavia 21 to gold. The bond strength of All Bond C&B cement had shown to be not significant difference from those of Panavia 21 and Variolink, when bonded to Rexillium and Midi-Gold, respectively. The bond strength of All Bond C&B Cement to amalgam was significantly greater (P<0.05) than those of the other materials tested. The shear bond strength to gold showed lower bonding for all adhesives when compared with Rexillium (P<.001). The ranking of bond strength to both alloys was as follows: Superbond>Panavia 21>All Bond C&B>Variolink. The nature of substrate to be used for bonding and the adhesive material itself are important factors in bonding which can be achieved between cast metals and prepared teeth with amalgam filling. Superbond should be successful as an adhesive for the attachment of all substrates tested, with the possible exception of amalgam, for which All Bond C&B Cement gives the best result.

  16. Microleakage of root-end filling materials.

    PubMed

    Fogel, H M; Peikoff, M D

    2001-07-01

    The purpose of this study was to evaluate the microleakage of various root-end filling materials using a fluid filtration system. Sixty extracted human single-rooted teeth were used. The crowns were removed, the canals prepared, and root-end fillings placed. The samples were divided into two control and five experimental groups. The root-end filling materials tested were: amalgam, Intermediate Restorative Material (IRM), a dentin-bonded resin, Super-EBA, and mineral trioxide aggregate. The results showed that amalgam root-end fillings demonstrated significantly more microleakage than Super-EBA, dentin-bonded resin, or mineral trioxide aggregate. There was no significant difference between amalgam and IRM. However IRM was also not significantly different from the other three groups. There were no significant differences between the other three groups.

  17. Bond strength of repaired amalgam restorations.

    PubMed

    Rey, Rosalia; Mondragon, Eduardo; Shen, Chiayi

    2015-01-01

    This in vitro study investigated the interfacial flexural strength (FS) of amalgam repairs and the optimal combination of repair materials and mechanical retention required for a consistent and durable repair bond. Amalgam bricks were created, each with 1 end roughened to expose a fresh surface before repair. Four groups followed separate repair protocols: group 1, bonding agent with amalgam; group 2, bonding agent with composite resin; group 3, mechanical retention (slot) with amalgam; and group 4, slot with bonding agent and amalgam. Repaired specimens were stored in artificial saliva for 1, 10, 30, 120, or 360 days before being loaded to failure in a 3-point bending test. Statistical analysis showed significant changes in median FS over time in groups 2 and 4. The effect of the repair method on the FS values after each storage period was significant for most groups except the 30-day storage groups. Amalgam-amalgam repair with adequate condensation yielded the most consistent and durable bond. An amalgam bonding agent could be beneficial when firm condensation on the repair surface cannot be achieved or when tooth structure is involved. Composite resin can be a viable option for amalgam repair in an esthetically demanding region, but proper mechanical modification of the amalgam surface and selection of the proper bonding system are essential.

  18. A comparison of tissue reactions to Ketac-Fil and amalgam.

    PubMed

    DeGrood, M E; Oguntebi, B R; Cunningham, C J; Pink, R

    1995-02-01

    The objective of this study was to compare the bone tissue reactions of Ketac-Fil to the most commonly used retrograde filling material, amalgam, in a rat model. Forty-eight Harlan rats were divided into three groups: amalgam, Ketac-Fil, and controls. Following anesthesia, the right lower incisor was extracted from each animal. A 3-mm long x 1-mm diameter polyethylene tube filled with amalgam or Ketac-Fil was implanted in the extraction site. The animals were killed at 14, 42, and 90 days; and the mandibles were dissected en block and processed histologically. The inflammatory reaction was assessed by the number of plasma cells, lymphocytes, polymorphonuclear neutrophils, giant cells, and osteoclasts within 100 microns of the implant. Bone formation was determined as either present or absent in the same area. There was no statistically significant bone apposition within 100 microns of the Ketac material, and there was a statistically significant increase in inflammation in the amalgam group. This study indicates that both Ketac-Fil and amalgam are relatively biocompatible, and provides support for clinical usage tests of Ketac-Fil as a retrograde filling material.

  19. Bulk-fill resin-based composite restorative materials: a review.

    PubMed

    Chesterman, J; Jowett, A; Gallacher, A; Nixon, P

    2017-03-10

    Resin-based composite (RBC) materials are increasingly being used for the restoration of posterior teeth. The increasing demand for aesthetic, tooth-coloured restorations coupled with the patient's concerns regarding the use of mercury containing restorations, has driven a surge in the use of RBC materials. With the Minamata Convention in 2013 calling for the phase-out of dental amalgam and dental schools increasingly teaching techniques for RBC restorations in posterior teeth, it is likely that the dental profession's reliance upon RBC for the restoration of posterior teeth will only increase. In order to simplify and speed-up the placement of large posterior RBCs, manufacturers have produced a range of materials which can be placed in single or deeper increments, known as bulk-fill RBCs. Over a relatively short period of time many bulk-fill RBCs have been marketed quoting increment depths between 4-10 mm. The placement of these larger increments of RBC may reduce the time needed when placing posterior restorations and thereby reduce technique sensitivity. This article aims to review the properties and handling characteristics of the bulk-fill RBC materials currently available, while advising the optimal techniques of placement.

  20. Barodontalgias, dental and orofacial barotraumas: a survey in Swiss divers and caisson workers.

    PubMed

    Zanotta, Cristina; Dagassan-Berndt, Dorothea; Nussberger, Peter; Waltimo, Tuomas; Filippi, Andreas

    2014-01-01

    Changing ambient pressure can lead to medical conditions in body cavities filled with air. Intraoral pain elicited by changes in pressure is referred to as barodontalgia. Dental barotraumas are defined as pressure-induced damages of teeth and restorations. The pathophysiologic background so far is not completely clear. The present study deals with dental and orofacial symptoms which can occur as a result of pressure variations. With the aid of cantonal administrations, diving associations, and tunnel construction firms, 520 pressure-exposed individuals (499 scuba/ professional divers, 21 caisson workers operating at excess pressure) were questioned regarding dental problems. A personal interview was conducted with affected individuals. Problems in the dental area were experienced by 15% of all respondents. Toothaches were suffered by 10.2% of the participants. Tooth injuries occurred in 6.3% of all interviewees (26 fractured amalgam restorations, 4 crown fractures, 3 losses of tooth fragments). A proportion of 11.3% among the respondents complained about temporomandibular joint problems or mucosal irritations (for example aphthae) related to the mouthpieces. Barotraumas outside the dental area were incurred by 31.9% of the divers. Of these, 69.9% concerned the ears and 65.6% occurred during the descent. Based on the results obtained from the survey and taking into account the current literature, recommendations for the prevention of barotraumas in divers and caisson workers were prepared. Diagnostic exclusion of dental pathologies and avoidance of retentive reconstruction materials are important factors for the prevention of barodontalgias and dental barotraumas.

  1. Amalgam Restorations: To Bond or Not.

    PubMed

    Larson, Thomas D

    2015-01-01

    This article will review the use of various liners used to eliminate microleakage in amalgam restorations. It will review the literature about whether amalgam restorations are improved by using a bonding process and if so specifically how it improves the patient outcome.

  2. Has resin-based composite replaced amalgam?

    PubMed

    Christensen, Gordon J; Child, Paul L

    2010-02-01

    The major health organizations in the world continue to accept amalgam use, but the "amalgam war" of the 1800s is still going on. The end is not in sight. There is little disagreement that amalgam serves well and, although controversial, it appears to have minimal to no health hazards. There is a wide variation in the relative amount of amalgam placed in developed countries, and many dentists in North America do not use it. However, amalgam is still being used at least some of the time by the majority of practitioners in North America, and most of those practitioners also place resin-based composite in Class II locations. The evolution from amalgam to tooth-colored restorations has been a slow and tumultuous journey. The acceptability of resin-based composite in Class II locations continues to be a question for some dentists, while others have concluded that amalgam is "dead." It would be highly desirable if some of dentists using the alleged poisonous properties of amalgam as a "practice building" ploy would find more legitimate methods to increase their practice activity.

  3. Morphology and electrochemical behavior of Ag-Cu nanoparticle-doped amalgams.

    PubMed

    Chung, Kwok-Hung; Hsiao, Li-Yin; Lin, Yu-Sheng; Duh, Jenq-Gong

    2008-05-01

    The aim of this study was to introduce Ag-Cu phase nanopowder as an additive to improve the corrosion behavior of dental amalgams. A novel Ag-Cu nanopowder was synthesized by the precipitation method. An amalgam alloy powder (World-Cap) was added and mixed with 5 wt.% and 10 wt.% of Ag-Cu nanopowders, respectively, to form experimental amalgam alloy powders. The original alloy powder was used as a control. Alloy powders were examined using X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy and electron probe microanalysis. Amalgam disk specimens of metallurgically prepared were tested in 0.9% NaCl solution using electrochemical methods. The changes in the corrosion potential and anodic polarization characteristics were determined. Corrosion potential data were analyzed statistically (n=3, analysis of variance, Tukey's test, p<0.05). The diameters of lamellar structure Ag-Cu nanoparticles were measured to be approximately 30 nm. The composition of the Ag-Cu nanoparticles determined by TEM-energy-dispersive spectroscopy was 56.28 at.% Ag-43.72 at.% Cu. A light-shaded phase was found mixing with dark Cu-Sn reaction particles in the reaction zones of Ag-Cu nanoparticle-doped amalgams. The Ag-Cu nanoparticle-doped amalgams exhibited zero current potentials more positive than the control (p<0.05) and no current peak was observed at -325mV that related to Ag-Hg phase and Cu6Sn5 phase in anodic polarization curves. The results indicated that the corrosion resistance of high-copper single-composition amalgam could be improved by Ag-Cu nanoparticle-doping.

  4. Dental Calculus Arrest of Dental Caries

    PubMed Central

    Keyes, Paul H.; Rams, Thomas E.

    2016-01-01

    Background An inverse relationship between dental calculus mineralization and dental caries demineralization on teeth has been noted in some studies. Dental calculus may even form superficial layers over existing dental caries and arrest their progression, but this phenomenon has been only rarely documented and infrequently considered in the field of Cariology. To further assess the occurrence of dental calculus arrest of dental caries, this study evaluated a large number of extracted human teeth for the presence and location of dental caries, dental calculus, and dental plaque biofilms. Materials and methods A total of 1,200 teeth were preserved in 10% buffered formal saline, and viewed while moist by a single experienced examiner using a research stereomicroscope at 15-25× magnification. Representative teeth were sectioned and photographed, and their dental plaque biofilms subjected to gram-stain examination with light microscopy at 100× magnification. Results Dental calculus was observed on 1,140 (95%) of the extracted human teeth, and no dental carious lesions were found underlying dental calculus-covered surfaces on 1,139 of these teeth. However, dental calculus arrest of dental caries was found on one (0.54%) of 187 evaluated teeth that presented with unrestored proximal enamel caries. On the distal surface of a maxillary premolar tooth, dental calculus mineralization filled the outer surface cavitation of an incipient dental caries lesion. The dental calculus-covered carious lesion extended only slightly into enamel, and exhibited a brown pigmentation characteristic of inactive or arrested dental caries. In contrast, the tooth's mesial surface, without a superficial layer of dental calculus, had a large carious lesion going through enamel and deep into dentin. Conclusions These observations further document the potential protective effects of dental calculus mineralization against dental caries. PMID:27446993

  5. Analysis of dental materials as an aid to identification in aircraft accidents.

    PubMed

    Wilson, G S; Cruickshanks-Boyd, D W

    1982-04-01

    The failure to achieve positive identification of aircrew following an aircraft accident need not prevent a full autopsy and toxicological examination to ascertain possible medical factors involved in the accident. Energy-dispersive electron microprobe analysis provides morphological, qualitative, and accurate quantitative analysis of the composition of dental amalgam. Wet chemical analysis can be used to determine the elemental composition of crowns, bridges and partial dentures. Unfilled resin can be analyzed by infrared spectroscopy. Detailed analysis of filled composite restorative resins has not yet been achieved in the "as-set" condition to permit discrimination between manufacturers' products. Future work will involve filler studies and pyrolysis of the composite resins by thermogravimetric analysis to determine percentage weight loss when the sample examined is subjected to a controlled heating regime. With these available techniques, corroborative evidence achieved from the scientific study of materials can augment standard forensic dental results to obtain a positive identification.

  6. Analysis of dental materials as an aid to identification in aircraft accidents

    SciTech Connect

    Wilson, G.S.; Cruickshanks-Boyd, D.W.

    1982-04-01

    The failure to achieve positive identification of aircrew following an aircraft accident need not prevent a full autopsy and toxicological examination to ascertain possible medical factors involved in the accident. Energy-dispersive electron microprobe analysis provides morphological, qualitative, and accurate quantitative analysis of the composition of dental amalgam. Wet chemical analysis can be used to determine the elemental composition of crowns, bridges and partial dentures. Unfilled resin can be analyzed by infrared spectroscopy. Detailed analysis of filled composite restorative resins has not yet been achieved in the as-set condition to permit discrimination between manufacturers' products. Future work will involve filler studies and pyrolysis of the composite resins by thermogravimetric analysis to determine percentage weight loss when the sample examined is subjected to a controlled heating regime. With these available techniques, corroborative evidence achieved from the scientific study of materials can augment standard forensic dental results to obtain a positive identification.

  7. Dynamic cure measurement of dental polymer composites using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Tomlins, Peter H.; Palin, Will M.; Shortall, Adrian C.

    2008-02-01

    Dental amalgam is being increasingly replaced by Light-activated resin-based dental composites. However, these materials are limited by inefficient setting reactions as a function of depth, constraining the maximum extent of cure and reducing biocompatibility. In this paper we demonstrate a novel metrological tool for dynamic monitoring of refractive index and thickness change through curing resins using spectral-domain optical coherence tomography. We present real-time measurements from pre- to post-cure of a series of un-filled bisphenol-A diglycidyl ether dimethacrylate (bisGMA) and triethylene glycol dimethacrylate (TEGDMA) resins with different inhibitor concentrations. Our results demonstrate that refractive index measurements are sensitive to the extent of cure of such resins and that the inhibitor concentration strongly affects the cure dynamics and final extent of cure.

  8. 21 CFR 872.3275 - Dental cement.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental cement. 872.3275 Section 872.3275 Food and... DENTAL DEVICES Prosthetic Devices § 872.3275 Dental cement. (a) Zinc oxide-eugenol—(1) Identification... filling or as a base cement to affix a temporary tooth filling, to affix dental devices such as crowns...

  9. 21 CFR 872.3275 - Dental cement.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental cement. 872.3275 Section 872.3275 Food and... DENTAL DEVICES Prosthetic Devices § 872.3275 Dental cement. (a) Zinc oxide-eugenol—(1) Identification... filling or as a base cement to affix a temporary tooth filling, to affix dental devices such as crowns...

  10. 21 CFR 872.3275 - Dental cement.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental cement. 872.3275 Section 872.3275 Food and... DENTAL DEVICES Prosthetic Devices § 872.3275 Dental cement. (a) Zinc oxide-eugenol—(1) Identification... filling or as a base cement to affix a temporary tooth filling, to affix dental devices such as crowns...

  11. 21 CFR 872.3275 - Dental cement.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental cement. 872.3275 Section 872.3275 Food and... DENTAL DEVICES Prosthetic Devices § 872.3275 Dental cement. (a) Zinc oxide-eugenol—(1) Identification... filling or as a base cement to affix a temporary tooth filling, to affix dental devices such as crowns...

  12. 21 CFR 872.3275 - Dental cement.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental cement. 872.3275 Section 872.3275 Food and... DENTAL DEVICES Prosthetic Devices § 872.3275 Dental cement. (a) Zinc oxide-eugenol—(1) Identification... filling or as a base cement to affix a temporary tooth filling, to affix dental devices such as crowns...

  13. An in vitro Evaluation of Microleakage of Posterior Teeth Restored with Amalgam, Composite and Zirconomer – A Stereomicroscopic Study

    PubMed Central

    Punia, Sandhya Kapoor; Bhat, Surekha; Singh, Gautam; Goyal, Pravesh; Oza, Swapnil; Raiyani, Chirag M.

    2015-01-01

    Background Numerous restorative materials are being used in dentistry to achieve adequate strength and restore aesthetics. However, a perfect ideal restorative material has still eluded dentist. Dental amalgam is versatile material with self-sealing property, but is unaesthetic. Other restorative materials like, composites require conservative preparation, but exhibits polymerisation shrinkage resulting in microleakage. To overcome these drawbacks a high strength restorative material reinforced with ceramic and zirconia fillers known as zirconomer has been introduced. The aim of this study was to evaluate the micro-leakage of these three different restorative materials. Materials and Methods Thirty non-carious human permanent first and second molars were utilized in this study. Class I cavities were prepared on the occlusal surface; cavities were then restored with amalgam, composite and zirconomer as per manufacture’s instruction. All samples were stored for 24 hours in distilled water followed by thermocycling. The entire tooth surface was painted with two coats of varnish to within 1mm of the restoration margins. The teeth were immersed in dye. Teeth were sectioned and observed under stereomicroscope. Results In this study the zirconomer exhibited the highest micro leakage as compared to composite and amalgam but composite having higher micro leakage as compared to amalgam and lower micro leakage as compared to zirconomer. Conclusion Even though composite and amalgam are being marketed aggressively and new material like zirconomer are on origin, amalgam still proves to be one of the best materials. PMID:26393208

  14. Radiochemical separation of gold by amalgam exchange

    USGS Publications Warehouse

    Ruch, R.R.

    1970-01-01

    A rapid and simple method for the radiochemical separation of gold after neutron activation. The technique is based on treatment with a dilute indium-gold amalgam, both chemical reduction and isotopic exchange being involved. The counting efficiency for 198Au in small volumes of the amalgam is good. Few interferences occur and the method is applicable to clays, rocks, salts and metals. The possibility of determining silver, platinum and palladium by a similar method is mentioned. ?? 1970.

  15. Factors affecting the placement or replacement of direct restorations in a dental school

    PubMed Central

    Silvani, Samara; Trivelato, Roberta Ferreira; Nogueira, Ruchele Dias; Gonçalves, Luciano de Souza; Geraldo-Martins, Vinícius Rangel

    2014-01-01

    Context: The knowledge of the reasons for the placement of direct restorations makes possible to trace an epidemiological profile of a specific population and to direct the teaching of dentistry to techniques that are commonly used today and will be continued performed in the future. Purpose: The aim of this study was to verify the reasons for placement and replacement of direct restorations in patients treated in the Dental Clinic of the Uberaba University – Brazil. Materials and Methods: This study evaluated 306 restorative procedures carried out on 60 patients. During the treatment planning, a form that contained information about the patient's gender, tooth number, the classification of restorations, the reasons for placement and replacement of amalgam and tooth-colored restorations, the material that had to be removed and the new material used to fill the cavities was filled for each patient. Statistical analysis was carried out using Chi-square test (α = 0.05). Results: The data showed that most of the patients were female (66.7%). Of all the restorations placed, 60.45% were 1st-time placements, while 39.55% were replacements. For 1st-time restorations, the main reason for placement was primary caries (76.76%), followed by non-carious cervical lesions (15.14%). The amalgam restorations were replaced more frequently (67.77%). The primary reason for replacements was the presence of secondary caries (for both previous amalgam (42.68%) and composite (66.67%) restorations (P < 0.05). The resin composite was the most indicated material for the new restorations (98.04%) (P < 0.05). Conclusions: The main reason for placement of direct restorations was primary caries, while secondary caries was the main reason for replacements. In almost all cases, the material used to fill the cavities was the resin composite. PMID:24808696

  16. On modeling and nanoanalysis of caries-affected dentin surfaces restored with Zn-containing amalgam and in vitro oral function.

    PubMed

    Toledano, Manuel; Aguilera, Fátima S; Osorio, Estrella; López-López, Modesto T; Cabello, Inmaculada; Toledano-Osorio, Manuel; Osorio, Raquel

    2015-12-19

    The aim of this research was to assess the influence of mechanical loading on the ability of Zn-free versus Zn-containing amalgams to promote remineralization at the dentin interface. Sound and caries-affected dentin surfaces (CAD) were restored using Zn-free or Zn-containing dental amalgams. Midcoronal dentin surfaces were studied by (1) atomic force microscopy analysis (including plot and phase imaging, nanoindentation test [modulus of Young (Ei), nanoroughness measurements, and fibril diameter assessment], (2) Raman spectroscopy/cluster analysis, (3) x-ray diffraction, (4) field emission electron microscope and energy-dispersive analysis, for morphological, mechanical, and physicochemical characterization. Analyses were performed before amalgam placement and after amalgam removal, at 24 h and 3 weeks of load cycling. Zn-free and Zn-containing amalgams restorations promoted an increase in the modulus of Young of CAD surfaces, after 3 weeks of load cycling; at this time, Zn-containing amalgams attained higher Ei than Zn-free restorations. Zn-containing amalgams induced tubular occlusion after load cycling, in both sound and CAD. Zn free-amalgams promoted remineralization of both intertubular and peritubular dentin in CAD substrata. These minerals were identified as calcium-phosphate deposits and crystals as hydroxyl-apatite with augmented crystallographic maturity but with some components of lattice distortion. Crosslinking of collagen diminished and secondary structure of collagen increased in CAD substrate restored with Zn-containing amalgam after 3 weeks of load cycling, indicating an advanced preservation, molecular organization, and orientation of collagen fibrils after load cycling. Plot and phase images permitted to observe the topographical changes which were promoted by the mineral deposits; in general, the indexes related to higher remineralization gave rise to a decrease of nanoroughness and an augmentation of the bandwidth of the collagen fibrils. Zn

  17. Restoration of posterior teeth in clinical practice: evidence base for choosing amalgam versus composite.

    PubMed

    Kovarik, Robert E

    2009-01-01

    This article reviews the current use of amalgam versus resin composite in posterior restorations and the evidence-base for choosing between these two treatment options. While much research has been published on the issue of the clinical use of amalgam versus resin composite, there are several issues that limit the true evidence-base on the subject. Furthermore, while the majority of published studies on posterior composites would seem to indicate equivalent clinical performance of resin composite to amalgam restorations, the studies that should be weighted much more heavily (randomized controlled trials) do not support the slant of the rest of the literature. As part of an evidence-based approach to private practice, clinicians need to be aware of the levels of evidence in the literature and need to properly inform patients of the true clinical outcomes that are associated with the use of amalgam versus resin composite for posterior restorations, so that patients are themselves making informed decisions about their dental care.

  18. An in vitro comparative SEM study of marginal adaptation of IRM, light- and chemically-cured glass ionomer, and amalgam in furcation perforations.

    PubMed

    Rajablou, N; Azimi, S

    2001-12-01

    The furcation regions of 30 human mandibular molars were perforated and sealed using four different materials: IRM, light- and chemically-cured glass ionomer cement (GIC), and amalgam. The materials were compared for marginal gaps in coronal, mid, and apical regions after routine SEM processing. While light-cured GIC showed the smallest gaps in the three regions, in mid and coronal regions chemically-cured GIC, and in apical regions amalgam, showed the largest gaps. IRM cases showed the highest rate of fillings with a good "fit", whereas the majority of amalgam cases and none of the chemically-cured GIC cases were overfilled.

  19. Effect of IRM on human dental pulp.

    PubMed

    Möller, B; Schröder, U; Granath, L

    1983-08-01

    IRM has been shown to be superior to conventional ZnOE cements. This study is a biotechnical investigation of IRM's effect on the dental pulp with respect to its sealing capacity. Enamel-dentin test bodies with IRM fillings were used in the in vitro part, where insufficiencies in sealing were detected with compressed air. The in vivo part included 44 buccal cavities in intact premolars. In teeth in which the material effect of IRM was tested, the IRM fillings were sealed off from the saliva by acid etch and composite resin. The observation intervals were 1, 7 and 28 days. Histologic changes such as capillary dilatations and presence of inflammatory cells in the pulp adjacent to the dentinal tubules involved in the cavity preparation were registered. The in vitro test showed no leakage in five cases out of six. After extreme temperature cycling, the leakage was comparable with that of zinc-containing amalgam of traditional alloy. The pulpal changes were mild and mainly ascribed to the material effect of IRM, since no evidence was found of leakage of biologic importance.

  20. Radiochemical separation of gallium by amalgam exchange

    USGS Publications Warehouse

    Ruch, R.R.

    1969-01-01

    An amalgam-exchange separation of radioactive gallium from a number of interfering radioisotopes has been developed. A dilute (ca. 0.3%) gallium amalgam is agitated with a slightly acidic solution of 72Ga3+ containing concentrations of sodium thiocyanate and either perchlorate or chloride. The amalgam is then removed and the radioactive gallium stripped by agitation with dilute nitric acid. The combined exchange yield of the perchlorate-thiocyanate system is 90??4% and that of the chloride-thiocyanate system is 75??4%. Decontamination yields of most of the 11 interfering isotopes studied were less than 0.02%. The technique is applicable for use with activation analysis for the determination of trace amounts of gallium. ?? 1969.

  1. Proximal Contact Repair of Complex Amalgam Restorations.

    PubMed

    Zguri, M N; Casey, J A; Jessup, J P; Vandewalle, K S

    2017-01-12

    The carving of a complex amalgam restoration may occasionally result in light proximal contact with the adjacent tooth. The purpose of this study was to investigate the strength of complex amalgam restorations repaired with a proximal slot amalgam preparation. Extracted human third molars of similar coronal size were sectioned 1 mm apical to the height of the contour using a saw and were randomly distributed into 9 groups of 10 teeth each. One pin was placed at each line angle of the flattened dentinal tooth surface. A metal matrix band was placed and an admixed alloy was condensed and carved to create a full crown contour but with a flat occlusal surface. A proximal slot was prepared with or without a retention groove and repaired using a single-composition spherical amalgam 15 minutes, 24 hours, one week, or six months after the initial crown condensation. The specimens were stored for 24 hours in 37°C water before fracture at the marginal ridge using a round-ended blade in a universal testing machine. The control group was not repaired. The mean maximum force in newtons and standard deviation were determined per group. Data were analyzed with a 2-way analysis of variance as well as Tukey and Dunnett tests (α=0.05). Significant differences were found between groups based on type of slot preparation (p=0.017) but not on time (p=0.327), with no significant interaction (p=0.152). No significant difference in the strength of the marginal ridge was found between any repair group and the unrepaired control group (p>0.076). The proximal repair strength of a complex amalgam restoration was not significantly different from an unrepaired amalgam crown. Placing a retention groove in the proximal slot preparation resulted in significantly greater fracture strength than a slot with no retention grooves. Time of repair had no significant effect on the strength of the repair.

  2. Composite veneering of complex amalgam restorations.

    PubMed

    Demarco, Flávio Fernando; Zanchi, César Henrique; Bueno, Márcia; Piva, Evandro

    2007-01-01

    In large posterior cavities, indirect restorations could provide improved performance when compared to direct restorations, but with higher cost and removal of sound tooth structure. Improved mechanical properties have resulted in good clinical performance for amalgam in large cavities but without an esthetic appearance. Resin composites have become popular for posterior restorations, mainly because of good esthetic results. A restorative technique is presented that combines the esthetic properties of directly bonded resin composite and the wide range of indications for amalgam in stress-bearing areas.

  3. The influence of a packable resin composite, conventional resin composite and amalgam on molar cuspal stiffness.

    PubMed

    Molinaro, J D; Diefenderfer, K E; Strother, J M

    2002-01-01

    Packable resin composites may offer improved properties and clinical performance over conventional resin composites or dental amalgam. This in vitro study examined the cuspal stiffness of molars restored with a packable resin composite, a conventional posterior microfilled resin composite and amalgam. Forty-eight intact caries-free human third molars were distributed into four treatment groups (n=12) so that the mean cross-sectional areas of all groups were equal. Standardized MOD cavity preparations were made and specimens restored using one of four restorative materials: (1) a spherical particle amalgam (Tytin); (2) Tytin amalgam with a dentin adhesive liner (OptiBond Solo); (3) a conventional microfilled posterior resin composite (Heliomolar); (4) a packable posterior resin composite (Prodigy Posterior). Cuspal stiffness was measured using a Bionix 200 biomaterials testing machine (MTS). Specimens were loaded vertically to 300 N at a crosshead speed of 1.0 mm/minute. Stiffness was measured at 10 intervals: (1) prior to cavity preparation (intact); (2) following cavity preparation, but before restoration; (3) seven days after restoration; then (4) 1, 2, 3, 4, 5, 6 and 12 months after restoration. All specimens were stored at 37 degrees C in deionized water throughout the study and thermocycled (5 degrees/55 degrees C; 2000 cycles) monthly for 12 months. Repeated Measures ANOVA revealed significant differences among treatment groups over time (p<0.0001). Cavity preparation reduced cuspal stiffness by more than 60%. At 12 months, the cuspal stiffness of restored teeth was, on average, 58% that of intact specimens. Neither the packable nor the conventional resin composite increased cuspal stiffness over that of amalgam.

  4. Novel Amalgams for In-Space Parts Fabrication

    NASA Technical Reports Server (NTRS)

    Cochran, Calvin; VanHoose, James R.; Grugel, Richard N.

    2012-01-01

    Sound amalgams can be fabricated by substituting Ga-In liquid for mercury; Cu-coated steel fibers bond well with the amalgam components. Inclusion of steel fibers significantly improved mechanical properties. An application scenario utilizing amalgams for in-space parts fabrication and repair was suggested. Procedure and materials need to be optimized

  5. Utility of Megavoltage Fan-Beam CT for Treatment Planning in a Head-And-Neck Cancer Patient with Extensive Dental Fillings Undergoing Helical Tomotherapy

    SciTech Connect

    Yang, Claus; Liu Tianxiao; Jennelle, Richard L.; Ryu, Janice K.; Vijayakumar, Srinivasan; Purdy, James A.; Chen, Allen M.

    2010-07-01

    The purpose of this study was to demonstrate the potential utility of megavoltage fan-beam computed tomography (MV-FBCT) for treatment planning in a patient undergoing helical tomotherapy for nasopharyngeal carcinoma in the presence of extensive dental artifact. A 28-year-old female with locally advanced nasopharyngeal carcinoma presented for radiation therapy. Due to the extensiveness of the dental artifact present in the oral cavity kV-CT scan acquired at simulation, which made treatment planning impossible on tomotherapy planning system, MV-FBCT imaging was obtained using the HI-ART tomotherapy treatment machine, with the patient in the treatment position, and this information was registered with her original kV-CT scan for the purposes of structure delineation, dose calculation, and treatment planning. To validate the feasibility of the MV-FBCT-generated treatment plan, an electron density CT phantom (model 465, Gammex Inc., Middleton, WI) was scanned using MV-FBCT to obtain CT number to density table. Additionally, both a 'cheese' phantom (which came with the tomotherapy treatment machine) with 2 inserted ion chambers and a generic phantom called Quasar phantom (Modus Medical Devices Inc., London, ON, Canada) with one inserted chamber were used to confirm dosimetric accuracy. The MV-FBCT could be used to clearly visualize anatomy in the region of the dental artifact and provide sufficient soft-tissue contrast to assist in the delineation of normal tissue structures and fat planes. With the elimination of the dental artifact, the MV-FBCT images allowed more accurate dose calculation by the tomotherapy system. It was confirmed that the phantom material density was determined correctly by the tomotherapy MV-FBCT number to density table. The ion chamber measurements agreed with the calculations from the MV-FBCT generated phantom plan within 2%. MV-FBCT may be useful in radiation treatment planning for nasopharyngeal cancer patients in the setting of extensive

  6. Costing dental restorations in public sector dental clinics.

    PubMed

    Khairiyah, Abdul Muttalib; Razak, Ishak Abdul; Raja-Latifah, Raja Jalludin; Tan, Bee Siew; Norain, Abu Talib; Noor-Aliyah, Ismail; Natifah, Che Salleh; Rauzi, Ismail

    2009-04-01

    The objective of this study is to share cost analysis methodology and to obtain cost estimates for posterior restorations in public sector dental clinics. Two urban and 2 rural dental clinics in Selangor state were selected. Only cases of 1 posterior restoration per visit by dental officers were included over 6 months. One capsulated amalgam type, 1 capsulated tooth-colored, and 1 non-capsulated tooth-colored material were selected. A clinical pathway form was formulated to collect data per patient. Annual capital and recurrent expenditures were collected per clinic. The mean cost of an amalgam restoration was RM 30.96 (sdRM 7.86); and tooth-colored restorations ranged from RM 33.00 (sdRM 8.43) to RM 41.10 (sdRM 10.61). Wherein 1 USD = RM 2.8. Restoration costs were 35% to 55% higher in clinics in rural areas than in urban areas. The findings demonstrate economy of scale for clinic operation and restoration costs with higher patient load. Costs per restoration were higher in rural than in urban dental clinics. More studies are recommended to address the dearth of dental costs data in Malaysia.

  7. Improving orthodontic bonding to silver amalgam.

    PubMed

    Zachrisson, B U; Büyükyilmaz, T; Zachrisson, Y O

    1995-01-01

    Flat rectangular tabs (n = 84) prepared from lathe-cut amalgam (ANA 2000) were subjected to aluminum oxide sandblasting or roughening with a diamond bur. Mandibular incisor edgewise brackets were bonded to these tabs using: Concise (Bis-GMA resin); one of three metal-bonding adhesives, viz., Superbond C&B (4-META resin), Panavia Ex (10-MDP Bis-GMA resin) or Geristore (composite base); and Concise after application of the intermediate resins All-Bond 2 Primers A+B, or the Scotch-Bond Multi-Purpose (SBMP) system. All specimens were stored in water at 37 degrees C for 24 hours before tensile bond strength testing. Alignment and uniform loading during testing were secured by engaging a hook in a circular ring soldered onto the bracket slot before bonding. Similar control brackets (n = 12) were bonded with Concise to extracted caries-free mandibular incisors. Bond failure sites were classified by a modified ARI system. Mean tensile bond strengths in the experimental group ranged from 3.4 to 6.4 MPa--significantly weaker than the control sample (13.2 MPa). Bond failure generally occurred at the amalgam/adhesive interface. Superbond C&B created the strongest bonds to amalgam; according to ANOVA and Duncan's Multiple-Range test, they were significantly stronger than the bonds with Panavia Ex and Concise, with Geristore in between. However, the bond strength of Concise to sandblasted amalgam was comparable to the Superbond C&B bonds when coupled with an intermediate application of All-Bond 2 Primers A+B. The SBMP, on the other hand, was less effective.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Cusp reinforcement by bonding of amalgam restorations.

    PubMed

    Pilo, R; Brosh, T; Chweidan, H

    1998-01-01

    The purpose of the present study was to assess the effectivenes of several adhesives in bonding amalgam in order to recover tooth stiffness. A non-destructive experimental methodology was adopted, using strain gauges bonded to the midbuccal surfaces of 40 teeth, with sequential evaluation of loaded intact, prepared and restored stages of the same tooth. Continuous strain measurement as a function of the applied load was acquired by A/D equipment and a data acquisition programme. The strain-force behaviour of the sound teeth under non-axial force up to 97.5 N served as the baseline. The five experimental groups (8 x 5) consisted of control (no adhesive) and four different adhesives. One-way analysis of variance with repeated measures was calculated for the deformation ratio, relative stiffness and recovery values. Reductions in tooth structure by cutting a mesio-occlusal-distal preparation, width one-third intercuspal distance, resulted in 39-52% loss of buccal cusp stiffness. Non-bonded amalgam produced negligible increase (5%) in the stiffness recovery values of the buccal cusps. The adhesives splinted the cusps together, thereby decreasing cuspal flexure and increasing relative stiffness values. Recovery values obtained ranged from 39% to 61%. Assuming that cusp fracture occurs as a result of brittle tooth structure fatigue, amalgam adhesives may contribute to the strengthening of weakened cusps.

  9. Effects of high temperature on different restorations in forensic identification: Dental samples and mandible

    PubMed Central

    Patidar, Kalpana A; Parwani, Rajkumar; Wanjari, Sangeeta

    2010-01-01

    Introduction: The forensic odontologist strives to utilize the charred human dentition throughout each stage of dental evaluation, and restorations are as unique as fingerprints and their radiographic morphology as well as the types of filling materials are often the main feature for identification. The knowledge of detecting residual restorative material and composition of unrecovered adjacent restoration is a valuable tool-mark in the presumptive identification of the dentition of a burned victim. Gold, silver amalgam, silicate restoration, and so on, have a different resistance to prolonged high temperature, therefore, the identification of burned bodies can be correlated with adequate qualities and quantities of the traces. Most of the dental examination relies heavily on the presence of the restoration as well as the relationship of one dental structure to another. This greatly narrows the research for the final identification that is based on postmortem data. Aim: The purpose of this study is to examine the resistance of teeth and different restorative materials, and the mandible, to variable temperature and duration, for the purpose of identification. Materials and Methods: The study was conducted on 72 extracted teeth which were divided into six goups of 12 teeth each based on the type of restorative material. (Group 1 - unrestored teeth, group 2 - teeth restored with Zn3(PO4)2, group 3 - with silver amalgam, group 4 with glass ionomer cement, group 5 - Ni-Cr-metal crown, group 6 - metal ceramic crown) and two specimens of the mandible. The effect of incineration at 400°C (5 mins, 15 mins, 30 mins) and 1100°C (15 mins) was studied. Results: Damage to the teeth subjected to variable temperatures and time can be categorized as intact (no damage), scorched (superficially parched and discolored), charred (reduced to carbon by incomplete combustion) and incinerated (burned to ashes). PMID:21189989

  10. METHOD AND APPARATUS FOR DETERMINING AMALGAM DECOMPOSITION RATE

    DOEpatents

    Johnson, R.W.; Wright, C.C.

    1962-04-24

    A method and apparatus for measuring the rate at which an amalgam decomposes in contact with aqueous solutions are described. The amalgam and an aqueous hydroxide solution are disposed in an electrolytic cell. The amalgam is used as the cathode of the cell, and an electrode and anode are disposed in the aqueous solution. A variable source of plating potential is connected across the cell. The difference in voltage between the amalgam cathode and a calibrated source of reference potential is used to control the variable source to null the difference in voltage and at the same time to maintain the concentration of the amalgam at some predetermined constant value. The value of the current required to maintain this concentration constant is indicative of the decomposition rate of the amalgam. (AEC)

  11. A technical report on repair of amalgam-dentin complex.

    PubMed

    Ozcan, M; Salihoğlu-Yener, E

    2011-01-01

    This clinical report describes a repair protocol for cusp fracture of a failed amalgam-dentin complex. A maxillary right first premolar with an amalgam restoration presented a buccal cusp fracture. Chairside repair has been undertaken by conditioning the existing amalgam restoration with silica coating (30 μm CoJet®-Sand), phosphoric acid etching the beveled enamel surface, priming dentin, and application of a bonding agent on both enamel and dentin. Thereafter, the amalgam was silanized (ESPE®-Sil), and opaque resin was applied and polymerized to mask the amalgam. The fractured buccal cusp was modeled using resin composite (Clearfil Photo Posterior) and photo-polymerized. Finally, the amalgam was refinished and refurbished and the composite was finished and polished.

  12. Fracture resistance of teeth restored with the bonded amalgam technique.

    PubMed

    Dias de Souza, G M; Pereira, G D; Dias, C T; Paulillo, L A

    2001-01-01

    This study evaluated the fracture resistance of maxillary premolars with MOD Class II cavity preparations restored with silver amalgam (G1), Scotchbond Multi Purpose Plus and silver amalgam (G2) and Panavia F and silver amalgam (G3). After the restorations were made, the specimens were stored at 37 degrees C for 24 hours at 100% humidity and submitted to the compression test. Statistical analysis of the data (ANOVA and Tukey Test) revealed no significant differences among the three groups that were studied.

  13. Effect of surface roughness on amalgam repair using adhesive systems.

    PubMed

    Giannini, Marcelo; Paulillo, Luis Alexandre Maffei Sartini; Ambrosano, Gláucia Maria Bovi

    2002-01-01

    The objective of this in vitro study was to evaluate the effect of three surface treatments and two adhesive systems on the shear bond strength of old and freshly placed amalgam. The results suggested that the intact amalgam showed a significantly higher strength than repaired groups and the strongest repaired specimens were made when the amalgam surfaces were roughened with a diamond bur or microetcher. The adhesive systems showed no significant differences on bond strength with the same superficial texture.

  14. 48. INTERIOR VIEW FROM THE WEST END OF THE AMALGAMATION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    48. INTERIOR VIEW FROM THE WEST END OF THE AMALGAMATION TABLES LOOKING NORTH TOWARDS THE STAMP BATTERIES WITH AMALGAM TRAPS SHOWN IN THE BOTTOM FOREGROUND. NOTE THE EXTANT EQUIPMENT IN THE FOREGROUND THAT THE PARK USES TO INTERPRET THE MILL. FROM LEFT TO RIGHT, A SCREEN FROM THE MORTAR BOX, A STAMP STOP. A (HUMAN'S) SHOE, A DIE FROM THE BOTTOM OF A MORTAR BOX, AN AMALGAM SCRAPPER AND AN AMALGAM BUCKET. - Standard Gold Mill, East of Bodie Creek, Northeast of Bodie, Bodie, Mono County, CA

  15. [Use of root-end filling materials in a surgical apical endodontic treatment in the Netherlands].

    PubMed

    Bronkhorst, M A; Bergé, S J; Van Damme, Ph A; Borstlap, W A; Merkx, M A W

    2008-08-01

    The material to be used for closing the root canal when carrying out a retrograde surgical apical endodontic treatment continues to be a subject of discussion. The aim of the present study was to inventory which materials are being used for this purpose at this moment by Dutch O&MF surgeons. All practicing Dutch OM&F surgeons (n = 195) were sent a questionnaire. The response rate was 77%. The results showed that at this moment intermediate restoration material (IRM) is the retrograde filling material most widely used by the Dutch O&MF surgeons (47.6%) in cases of surgical apical endodontic treatment. Amalgam, with 35%, was second, especially due to its plasticity and convenience. The choice of material is just as often determined by tradition, personal preference, individual experience or scientific results. There seems to be no relationship between the dental surgeon's number of years of experience and the type of retro grade filling material which he or she uses.

  16. Ablation by-products of dental materials from the Er:YAG laser and the dental handpiece

    NASA Astrophysics Data System (ADS)

    Wigdor, Harvey A.; Visuri, Steven R.; Walsh, Joseph T., Jr.

    1995-05-01

    Recently there has been much interest in lasers and their potential use to replace the dental drill. The research has been directed towards vital dental tissues. It must be understood that any laser to be used in dentistry which will replace the dental drill must also ablate and remove existing dental materials. Some concern exists about the ablation products when the Er:YAG laser is used to ablate dental materials. It is incumbent on the professionals using these lasers to understand the materials being produced by these lasers and protect themselves and their patients from possible toxic products. It is the intent of this paper to evaluate the products produced by the ablation of both dental amalgam and composite dental restorative materials and compare them with those produced by the traditional dental handpiece (drill).

  17. Terrane amalgamation in the Philippine Sea margin

    NASA Astrophysics Data System (ADS)

    Hall, Robert; Nichols, Gary J.

    1990-09-01

    The Philippine Sea plate includes plateaus of thickened crust interpreted as imbricated ophiolite and arc-related terranes of late Mesozoic-early Tertiary age separated by thinner oceanic crust. The arrival of plateaus at the subducting southwest margin of the Philippine Sea plate has caused the Philippine Trench to propagate southward in increments and caused transfer of terranes to the Philippine margin. New data from the Halmahera region indicate that the position, nature and evolution of plate boundaries have been strongly influenced by the heterogeneous character of the Philippine Sea plate. At present the Philippine Trench terminates at an oceanic plateau which is structurally continuous with an old forearc and ophiolite terrane on Halmahera. The position of this terrane has caused Philippine Sea plate-Eurasia convergence to be transferred from subduction at the Philippine Trench to the Molucca Sea Collision Zone through a broad NE-SW dextral transpressional zone across Halmahera. This plate boundary configuration is unstable and requires the future development of a new subduction zone to the east of Halmahera which will result in amalgamation of the Halmahera ophiolite terrane to the Philippine margin. In the Halmahera region amalgamation of terranes to the evolving Philippine microcontinent is currently in process.

  18. 12-year survival of composite vs. amalgam restorations.

    PubMed

    Opdam, N J M; Bronkhorst, E M; Loomans, B A C; Huysmans, M C D N J M

    2010-10-01

    Information about the long-term clinical survival of large amalgam and composite restorations is still lacking. This retrospective study compares the longevity of three- and four-/five-surface amalgam and composite restorations relative to patients' caries risk. Patient records from a general practice were used for data collection. We evaluated 1949 large class II restorations (1202 amalgam/747 composite). Dates of placement, replacement, and failure were recorded, and caries risk of patients was assessed. Survival was calculated from Kaplan-Meier statistics. After 12 years, 293 amalgam and 114 composite restorations had failed. Large composite restorations showed a higher survival in the combined population and in the low-risk group. For three-surface restorations in high-risk patients, amalgam showed better survival.

  19. Mercury burden and health impairment in dental auxilaries. Final report

    SciTech Connect

    Shapiro, I.M.; Bloch, P.; Ship, I.I.; Spitz, L.; Summer, A.

    1988-01-01

    An effort was made to develop a safe and effective x-ray fluorescence system for monitoring mercury and other elements in human tissues in-situ, to determine mercury levels in 207 dental auxiliaries exposed to dental amalgam on the job, to evaluate mercury in matching nonexposed populations and in 298 dentists using mercury amalgam, and to evaluate deficiencies in central and peripheral nervous systems resulting from the mercury exposure. Mercury levels were below 20 micrograms/gram in 60% of the dentists and 90% of the dental auxiliaries. Dentists with the higher mercury concentrations in their heads or wrists had considerably longer median motor distal latencies and median F-wave latency. Five of them demonstrated abnormalities consistent with carpal tunnel syndrome; seven had polyneuropathies defined as reduced motor or sensory conduction velocities of response amplitudes in two or more nerves. Neuropsychological tests indicated both groups of dental workers were adversely affected by mercury exposure.

  20. Class I and Class II silver amalgam and resin composite posterior restorations: teaching approaches in Canadian faculties of dentistry.

    PubMed

    McComb, Dorothy

    2005-06-01

    A 10-question survey was mailed to the 10 Canadian faculties of dentistry to determine current approaches to teaching undergraduates about silver amalgam and resin composite for posterior restorations in adults and children. Responses were received from all 10 pedodontic programs and from 8 of the 10 operative and restorative programs. The use of silver amalgam and posterior composite for restorations of primary and permanent teeth is covered in the curricula of all dental schools, but the relative emphasis on the 2 materials varies. In the operative and restorative programs, curriculum time devoted to silver amalgam is either greater than or equal to that devoted to posterior composite. Five of the 8 schools reported greater educational emphasis on silver amalgam for the permanent dentition; however, course directors noted that the preference among patients seen in clinics is tending toward composite restorations. Curricula appear designed to educate students about the optimal use of both materials. Requirements for performance of restorations during training generally do not specify the type of material; these requirements range from 60 restorations to 250 surfaces. Five of the 8 schools conduct clinical competency tests with both materials. The responses from the pedodontic programs were more diverse. The proportion of curriculum time devoted to each type of material in these programs ranged from less than 25% to more than 75%. Five schools reported more emphasis on silver amalgam, 3 schools reported equal emphasis, and 2 schools reported more emphasis on posterior composite. No clinical requirements were specified in any of the undergraduate pedodontic programs. Within some of the faculties, there were differences between the operative and restorative program and the pedodontic program with respect to emphasis on different materials for the posterior dentition.

  1. Sensibility of Teeth Having Based versus Non-Based Amalgam Restorations: A Clinical Study.

    DTIC Science & Technology

    1983-04-01

    623-37, Oct. 1971. 101. Guevara, M., and McClugage, S. The effects of intrusive forces upon the microvasculature of the dental pulp . Angle Orthodont ...widespread. Certainly, pulp protection was not unknown. Harrower (3), in 1886, stated that a protective layer of varnish was used under gold fillings as...8217 " :- .. ".....-.... .... . .-. .- ........-.... ~-.. .........-... . . . . . 4 textbook "A System of Dental Surgery", wrote that pulp capping could be done by means of covering the deep

  2. Reactions of connective tissue to amalgam, intermediate restorative material, mineral trioxide aggregate, and mineral trioxide aggregate mixed with chlorhexidine.

    PubMed

    Sumer, Mahmut; Muglali, Mehtap; Bodrumlu, Emre; Guvenc, Tolga

    2006-11-01

    The aim of this study was to histopathologically examine the biocompatibility of the high-copper amalgam, intermediate restorative material (IRM), mineral trioxide aggregate (MTA), and MTA mixed with chlorhexidine (CHX). This study was conducted to observe the rat subcutaneous connective tissue reaction to the implanted tubes filled with amalgam, IRM, MTA, and MTA mixed with CHX. The animals were sacrificed 15, 30, and 60 days after the implantation procedure. The implant sites were excised and prepared for histological evaluation. Sections of 5 to 6 microm thickness were cut by a microtome and stained with hemotoxylin eosin and examined under a light microscope. The inflammatory reactions were categorized as weak (none or few inflammatory cells < or =25 cells), moderate (>25 cells), and severe (a lot of inflammatory cells not to be counted, giant cells, and granulation tissue). Thickness of fibrous capsules measured five different areas by the digital imaging and the mean values were scored. Amalgam, IRM, and MTA mixed with CHX caused a weak inflammatory response on days 15, 30, and 60. MTA provoked an initial severe inflammatory response that subsided at the 30 and 60 day study period. A clear fibrous capsule was observed beginning from the 15 days in all of the groups. Within the limits of this study, amalgam, IRM, MTA, and MTA mixed with CHX materials were surrounded by fibrous connective tissue indicated that they were well tolerated by the tissues, therefore, MTA/CHX seemed to be biocompatible.

  3. Effect of IRM root end fillings on healing after replantation.

    PubMed

    Pitt Ford, T R; Andreasen, J O; Dorn, S O; Kariyawasam, S P

    1994-08-01

    The effect of IRM as a root end filling placed in teeth prior to replantation was examined in 21 molar teeth in monkeys. After extraction, root ends were resected, the canals contaminated with oral bacteria, root end cavities prepared, and fillings of IRM or amalgam placed prior to replantation. After 8 wk the jaws were removed and prepared for histological examination. Bacteria were demonstrated in only 9 of 15 teeth filled with IRM; 18 of the roots (60%) were associated with inflammation, which was only moderate or severe around 5 (17%), and extended > 0.1 mm around only 2 roots. In contrast, of the 6 teeth filled with amalgam, all contained bacteria in the root canals and 11 roots were associated with moderate or severe inflammation, which around 8 roots extended > 0.5 mm. The difference in severity of inflammation for the two materials was statistically significant (p < 0.001). The tissue response to root end fillings of IRM in replanted teeth was less severe and less extensive than that to amalgam.

  4. Influence of dental materials on dental MRI

    PubMed Central

    Tymofiyeva, O; Vaegler, S; Rottner, K; Boldt, J; Hopfgartner, AJ; Proff, PC; Richter, E-J; Jakob, PM

    2013-01-01

    Objectives: To investigate the potential influence of standard dental materials on dental MRI (dMRI) by estimating the magnetic susceptibility with the help of the MRI-based geometric distortion method and to classify the materials from the standpoint of dMRI. Methods: A series of standard dental materials was studied on a 1.5 T MRI system using spin echo and gradient echo pulse sequences and their magnetic susceptibility was estimated using the geometric method. Measurements on samples of dental materials were supported by in vivo examples obtained in dedicated dMRI procedures. Results: The tested materials showed a range of distortion degrees. The following materials were classified as fully compatible materials that can be present even in the tooth of interest: the resin-based sealer AH Plus® (Dentsply, Maillefer, Germany), glass ionomer cement, gutta-percha, zirconium dioxide and composites from one of the tested manufacturers. Interestingly, composites provided by the other manufacturer caused relatively strong distortions and were therefore classified as compatible I, along with amalgam, gold alloy, gold–ceramic crowns, titanium alloy and NiTi orthodontic wires. Materials, the magnetic susceptibility of which differed from that of water by more than 200 ppm, were classified as non-compatible materials that should not be present in the patient’s mouth for any dMRI applications. They included stainless steel orthodontic appliances and CoCr. Conclusions: A classification of the materials that complies with the standard grouping of materials according to their magnetic susceptibility was proposed and adopted for the purposes of dMRI. The proposed classification can serve as a guideline in future dMRI research. PMID:23610088

  5. Evaluation of various concentrations of alkaline surface treatment on interfacial bond strengths of amalgam bonded to amalgam.

    PubMed

    Mirza, Asaad Javaid; Ahmad, Asif; Mohammad, Taqi; Khan, Zahid Akhter

    2013-09-01

    This study was done to assess the influence of alkaline surface modification on interfacial bond strength of existing fractured (old) amalgam restoration bonded to fresh amalgam. Old and Fresh amalgam interfaced samples were prepared by applying a 4-methacryloyloxyethy trimellitate anhydride (4-META) containing adhesive. The adhesive used was Amalgabond (Parkell, Farmingdale, NY 11735, USA). Four concentrations of calcium hydroxide Ca(OH)2 solutions were used as a surface modifiers for old amalgam to increase the pH of the amalgam surfaces. The concentrations used were 2.5, 5, 10 and 15%. Direct measurement of the interfacial bond strength was carried out using an electromechanical universal tensile testing machine at crosshead speed of 10mm per minute. Results show that all the calcium hydroxide modified samples produced the increased tensile bond strength (TBS) as compared to their control group. The highest values of bond strength were achieved using 15% Ca(OH)2 solution as surface modifier. Pretreatment of fractured amalgam with calcium hydroxide improves the bond strength of 4-META adhesives. Its use in repair of amalgam may therefore be considered.

  6. Review of Spaceflight Dental Emergencies

    NASA Technical Reports Server (NTRS)

    Menon, Anil

    2012-01-01

    All exploration class missions--extending beyond earth's orbit--differ from existing orbital missions by being of longer duration and often not having a means of evacuation. If an exploration mission extends beyond a year, then there will be a greater lapse since the crewmembers last terrestrial dental exams, which routinely occur each year. This increased time since professional dental care could increase the chance of a dental emergency such as intractable pain, dental decay requiring a temporary filling, crown replacement, exposed pulp, abscess, tooth avulsion, or toothache. Additionally, any dental emergency will have to be treated in-flight with available resources and personnel who may not have extensive training in dental care. Thus, dental emergencies are an important risk to assess in preparation for exploration missions.

  7. Control of Dental Amalgam in Wastewater at the Naval Dental Clinic, Norfolk, Virginia

    DTIC Science & Technology

    1993-12-01

    Rebulations ....................................................... 1 3 3.2 Hazardous Waste Regulations ............................................. 14...infectious and hazardous waste regulations and their application in this situation. 3. Perform a literature search to identify and evaluate potential...regulations are based on and 0 have primarily the same requirements as RCRA, a detailed discussion of them is not included. * 3.2 Hazardous Waste Regulations Any

  8. Determination of ablation threshold for composite resins and amalgam irradiated with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Freitas, A. Z.; Freschi, L. R.; Samad, R. E.; Zezell, D. M.; Gouw-Soares, S. C.; Vieira, N. D., Jr.

    2010-03-01

    The use of laser for caries removal and cavity preparation is already a reality in the dental clinic. The objective of the present study was to consider the viability of ultrashort laser pulses for restorative material selective removal, by determining the ablation threshold fluence for composite resins and amalgam irradiated with femtosecond laser pulses. Lasers pulses centered at 830 nm with 50 fs of duration and 1 kHz of repetition rate, with energies in the range of 300 to 770 μJ were used to irradiate the samples. The samples were irradiated using two different geometrical methods for ablation threshold fluence determinations and the volume ablation was measured by optical coherence tomography. The shape of the ablated surfaces were analyzed by optical microscopy and scanning electron microscopy. The determined ablation threshold fluence is 0.35 J/cm2 for the composite resins Z-100 and Z-350, and 0.25 J/cm2 for the amalgam. These values are half of the value for enamel in this temporal regime. Thermal damages were not observed in the samples. Using the OCT technique (optical coherence tomography) was possible to determine the ablated volume and the total mass removed.

  9. Usefulness of an energy-binned photon-counting x-ray detector for dental panoramic radiographs

    NASA Astrophysics Data System (ADS)

    Fukui, Tatsumasa; Katsumata, Akitoshi; Ogawa, Koichi; Fujiwara, Shuu

    2015-03-01

    A newly developed dental panoramic radiography system is equipped with a photon-counting semiconductor detector. This photon-counting detector acquires transparent X-ray beams by dividing them into several energy bands. We developed a method to identify dental materials in the patient's teeth by means of the X-ray energy analysis of panoramic radiographs. We tested various dental materials including gold alloy, dental amalgam, dental cement, and titanium. The results of this study suggest that X-ray energy scattergram analysis could be used to identify a range of dental materials in a patient's panoramic radiograph.

  10. Streptococcus mutans-induced secondary caries adjacent to glass ionomer cement, composite resin and amalgam restorations in vitro.

    PubMed

    Gama-Teixeira, Adriana; Simionato, Maria Regina Lorenzeti; Elian, Silvia Nagib; Sobral, Maria Angela Pita; Luz, Maria Aparecida Alves de Cerqueira

    2007-01-01

    The aim of this study was to define, in vitro, the potential to inhibit secondary caries of restorative materials currently used in dental practice. Standard cavities were prepared on the buccal and lingual surfaces of fifty extracted human third molars. The teeth were randomly divided into five groups, each one restored with one of the following materials: glass ionomer cement (GIC); amalgam; light-cured composite resin; ion-releasing composite; and light-cured, fluoride-containing composite resin. The teeth were thermocycled, sterilized with gamma irradiation, exposed to a cariogenic challenge using a bacterial system using Streptococcus mutans, and then prepared for microscopic observation. The following parameters were measured in each lesion formed: extension, depth, and caries inhibition area. The outer lesions developed showed an intact surface layer and had a rectangular shape. Wall lesions were not observed inside the cavities. After Analysis of Variance and Component of Variance Models Analysis, it was observed that the GIC group had the smallest lesions and the greatest number of caries inhibition areas. The lesions developed around Amalgam and Ariston pHc restorations had an intermediate size and the largest lesions were observed around Z-100 and Heliomolar restorations. It may be concluded that the restorative materials GIC, amalgam and ion-releasing composites may reduce secondary caries formation.

  11. 21 CFR 872.3310 - Coating material for resin fillings.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Coating material for resin fillings. 872.3310... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3310 Coating material for resin fillings. (a) Identification. A coating material for resin fillings is a device intended to be applied to...

  12. 21 CFR 872.3310 - Coating material for resin fillings.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Coating material for resin fillings. 872.3310... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3310 Coating material for resin fillings. (a) Identification. A coating material for resin fillings is a device intended to be applied to...

  13. 21 CFR 872.3820 - Root canal filling resin.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Root canal filling resin. 872.3820 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device composed of material, such as methylmethacrylate,...

  14. 21 CFR 872.3820 - Root canal filling resin.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Root canal filling resin. 872.3820 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device composed of material, such as methylmethacrylate,...

  15. 21 CFR 872.3820 - Root canal filling resin.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Root canal filling resin. 872.3820 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device composed of material, such as methylmethacrylate,...

  16. 21 CFR 872.3310 - Coating material for resin fillings.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Coating material for resin fillings. 872.3310... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3310 Coating material for resin fillings. (a) Identification. A coating material for resin fillings is a device intended to be applied to...

  17. 21 CFR 872.3310 - Coating material for resin fillings.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Coating material for resin fillings. 872.3310... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3310 Coating material for resin fillings. (a) Identification. A coating material for resin fillings is a device intended to be applied to...

  18. 21 CFR 872.3310 - Coating material for resin fillings.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Coating material for resin fillings. 872.3310... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3310 Coating material for resin fillings. (a) Identification. A coating material for resin fillings is a device intended to be applied to...

  19. Dental Procedures.

    PubMed

    Ramponi, Denise R

    2016-01-01

    Dental problems are a common complaint in emergency departments in the United States. There are a wide variety of dental issues addressed in emergency department visits such as dental caries, loose teeth, dental trauma, gingival infections, and dry socket syndrome. Review of the most common dental blocks and dental procedures will allow the practitioner the opportunity to make the patient more comfortable and reduce the amount of analgesia the patient will need upon discharge. Familiarity with the dental equipment, tooth, and mouth anatomy will help prepare the practitioner for to perform these dental procedures.

  20. Amalgam buildups: shear strength and dentin sealing properties.

    PubMed

    Pashley, E L; Comer, R W; Parry, E E; Pashley, D H

    1991-01-01

    The retentive strength and sealing properties of amalgam buildups were compared in vitro in three groups of specimens. All teeth were prepared with flat, nonretentive surfaces. In the first group, the amalgam buildups were retained by four self-threading Minim pins. In the second group, retention was provided by a circumferential slot prepared in the dentin just inside the DEJ. The third group utilized an adhesive resin for retention. Dentin permeability was measured as a hydraulic conductance before and after placement of the amalgam buildups and before and after thermocycling. All methods of retention sealed dentin very well even in the absence of cavity varnish. The 90 degree retentive strength was: pins, 10.3 +/- 0.9 MPa; slots, 4.1 +/- 0.5 MPa; resin, 3.1 +/- 0.8 MPa (mean +/- SEM).

  1. Fracture resistance of premolars with bonded class II amalgams.

    PubMed

    Dias de Souza, Grace Mendonça; Pereira, Gisele Damiana Silveira; Dias, Carlos Tadeu Santos; Paulillo, Luis Alexandre Maffei Sartini

    2002-01-01

    This study evaluated the fracture resistance of maxillary premolars with MOD cavity preparation and simulated periodontal ligament. The teeth were restored with silver amalgam (G1), Scotchbond Multi-Purpose Plus and silver amalgam (G2) and Panavia F and silver amalgam (G3). After restorations were made, the specimens were stored at 37 degrees C for 24 hours at 100% humidity and submitted to the compression test in the Universal Testing Machine (Instron). The statistical analysis of the results (ANOVA and Tukey Test) revealed that the fracture resistance of group 2 (G2=105.720 kgF) was superior to those of groups 1 (G1=72.433 kgF) and 3 (G3=80.505 kgF) that did not differ between them.

  2. Novel Amalgams for In-Space Fabrication of Replacement Parts

    NASA Technical Reports Server (NTRS)

    Cochran, Calvin T.; Van Hoose, James R.; Grugel, R. N.

    2012-01-01

    Being able to fabricate replacement parts during extended space flight missions precludes the weight, storage volume, and speculation necessary to accommodate spares. Amalgams, widely used in dentistry, are potential candidates for fabricating parts in microgravity environments as they are moldable, do not require energy for melting, and do not pose fluid handling problems. Unfortunately, amalgams have poor tensile strength and the room temperature liquid component is mercury. To possibly resolve these issues a gallium-indium alloy was substituted for mercury and small steel fibers were mixed in with the commercial alloy powder. Subsequent microscopic examination of the novel amalgam revealed complete bonding of the components, and mechanical testing of comparable samples showed those containing steel fibers to have a significant improvement in strength. Experimental procedures, microstructures, and test results are presented and discussed in view of further improving properties.

  3. Integrated starting and running amalgam assembly for an electrodeless fluorescent lamp

    DOEpatents

    Borowiec, Joseph Christopher; Cocoma, John Paul; Roberts, Victor David

    1998-01-01

    An integrated starting and running amalgam assembly for an electrodeless SEF fluorescent lamp includes a wire mesh amalgam support constructed to jointly optimize positions of a starting amalgam and a running amalgam in the lamp, thereby optimizing mercury vapor pressure in the lamp during both starting and steady-state operation in order to rapidly achieve and maintain high light output. The wire mesh amalgam support is constructed to support the starting amalgam toward one end thereof and the running amalgam toward the other end thereof, and the wire mesh is rolled for friction-fitting within the exhaust tube of the lamp. The positions of the starting and running amalgams on the wire mesh are jointly optimized such that high light output is achieved quickly and maintained, while avoiding any significant reduction in light output between starting and running operation.

  4. Health maintenance facility: Dental equipment requirements

    NASA Technical Reports Server (NTRS)

    Young, John; Gosbee, John; Billica, Roger

    1991-01-01

    The objectives were to test the effectiveness of the Health Maintenance Facility (HMF) dental suction/particle containment system, which controls fluids and debris generated during simulated dental treatment, in microgravity; to test the effectiveness of fiber optic intraoral lighting systems in microgravity, while simulating dental treatment; and to evaluate the operation and function of off-the-shelf dental handheld instruments, namely a portable dental hand drill and temporary filling material, in microgravity. A description of test procedures, including test set-up, flight equipment, and the data acquisition system, is given.

  5. Acid-Assisted Consolidation of Silver Alloys for Direct Fillings

    DTIC Science & Technology

    1998-01-01

    Eichmiller, Kathleen M. Hoffman, and Anthony A. Guiseppetti American Dental Association Health Foundation, Paffenbarger Research Center, National Institute...of Standards and Technology, Gaithersburg, MD 20899-0001 and Michael M. Wray and Rangall J. Avers Naval Dental School Bethesda, MD 20899-5602 Silver...rich metal powders cold-welded by consolidation have been investigated as pos- sible direct dental filling material. The sur- face of the silver

  6. Comparative study of mechanical properties of dental restorative materials and dental hard tissues in compressive loads

    PubMed Central

    Lee, Jong Yeop

    2014-01-01

    There are two objectives. One is to show the differences in the mechanical properties of various dental restorative materials compared to those of enamel and dentin. The other is to ascertain which dental restorative materials are more suitable for clinical treatments. Amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy were processed as dental restorative material specimens. The specimens (width, height, and length of 1.2, 1.2, and 3.0 mm, respectively) were compressed at a constant loading speed of 0.1 mm/min. The maximum stress (115.0 ± 40.6, 55.0 ± 24.8, 291.2 ± 45.3, 274.6 ± 52.2, 2206.0 ± 522.9, and 953.4 ± 132.1 MPa), maximum strain (7.8% ± 0.5%, 4.0% ± 0.1%, 12.7% ± 0.8%, 32.8% ± 0.5%, 63.5% ± 14.0%, and 45.3% ± 7.4%), and elastic modulus (1437.5 ± 507.2, 1548.4 ± 583.5, 2323.4 ± 322.4, 833.1 ± 92.4, 3895.2 ± 202.9, and 2222.7 ± 277.6 MPa) were evident for amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy, respectively. The reference hardness value of amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy was 90, 420, 130–135, 86.6–124.2, 1250, and 349, respectively. Since enamel grinds food, its abrasion resistance is important. Therefore, hardness value should be prioritized for enamel. Since dentin absorbs bite forces, mechanical properties should be prioritized for dentin. The results suggest that gold alloy simultaneously has a hardness value lower than enamel (74.8 ± 18.1), which is important in the wear of the opposing natural teeth, and higher maximum stress, maximum strain, and elastic modulus than dentin (193.7 ± 30.6 MPa, 11.9% ± 0.1%, 1653.7 ± 277.9 MPa, respectively), which are important considering the rigidity to absorb bite forces. PMID:25352921

  7. Blood lead level and dental caries in school-age children.

    PubMed Central

    Gemmel, Allison; Tavares, Mary; Alperin, Susan; Soncini, Jennifer; Daniel, David; Dunn, Julie; Crawford, Sybil; Braveman, Norman; Clarkson, Thomas W; McKinlay, Sonja; Bellinger, David C

    2002-01-01

    The association between blood lead level and dental caries was evaluated in cross-sectional analyses of baseline data for 543 children 6-10 years old screened for enrollment in the Children's Amalgam Trial, a study designed to assess potential health effects of mercury in silver fillings. Approximately half of the children were recruited from an urban setting (Boston/Cambridge, MA, USA) and approximately half from a rural setting (Farmington, ME, USA). Mean blood lead level was significantly greater among the urban subgroup, as was the mean number of carious tooth surfaces. Blood lead level was positively associated with number of caries among urban children, even with adjustment for demographic and maternal factors and child dental practices. This association was stronger in primary than in permanent dentition and stronger for occlusal, lingual, and buccal tooth surfaces than for mesial or distal surfaces. In general, blood lead was not associated with caries in the rural subgroup. The difference between the strength of the associations in the urban and rural settings might reflect the presence of residual confounding in the former setting, the presence of greater variability in the latter setting in terms of important caries risk factors (e.g., fluoride exposure), or greater exposure misclassification in the rural setting. These findings add to the evidence supporting a weak association between children's lead exposure and caries prevalence. A biologic mechanism for lead cariogenicity has not been identified, however. Our data are also consistent with residual confounding by factors associated with both elevated lead exposure and dental caries. PMID:12361944

  8. Excisional wound healing following the use of IRM as a root-end filling material.

    PubMed

    Harrison, J W; Johnson, S A

    1997-01-01

    Intermediate Restorative Material (IRM) has been advocated as a root-end filling material based primarily on reports of clinical success and various leakage studies. The objectives of this study were to determine the excisional wound healing responses of the periradicular tissues to IRM root-end filling material and to compare this with the wound healing responses to amalgam and orthograde gutta-percha root-end filling materials. Mandibular premolars in dogs were obturated, root-ends resected, and the healing responses associated with root-end fillings of IRM, amalgam, and orthograde gutta-percha were evaluated microscopically and radiographically at postsurgical intervals of 10 and 45 days. The excisional wound healing responses associated with IRM root-end fillings were normal at both postsurgical intervals. There was no evidence of inhibition of dentoalveolar or osseous wound healing associated with IRM, amalgam, or orthograde gutta-percha. Statistical analysis showed no difference in wound healing between the 3 root-end filling materials.

  9. A systematic technique for carving amalgam and composite restorations.

    PubMed

    Kilistoff, A

    2011-01-01

    Both amalgam and composite restorations can quickly and accurately be carved using a systematic technique. By following the outlined steps, anatomically accurate restorations can be easily achieved. Inlay wax is used as a training medium to negate the setting constraints and as a high fidelity simulation.

  10. Test of Picture-Text Amalgams in Procedural Texts.

    ERIC Educational Resources Information Center

    Stone, David Edey

    Designed to assess how people read and comprehend information presented in picture-text amalgams in procedural texts, this instrument presents various combinations of text information and illustrative information on slides. Subjects are assigned to one of four conditions and directed to follow the instructions presented on the slides. Videotapes…

  11. Solidification/Stabilization of Elemental Mercury Waste by Amalgamation

    SciTech Connect

    Yim, S. P.; Ahn, B. G.; Lee, H. J.; Shon, J. S.; Chung, H.; Kim, K. J.; Lee, C. K.

    2003-02-24

    Experiments on solidification of elemental mercury waste were conducted by amalgamation with several metal powders such as copper, zinc, tin, brass and bronze. Unlike the previous studies which showed a dispersible nature after solidification, the waste forms were found to possess quite large compressive strengths in both copper and bronze amalgam forms. The durability was also confirmed by showing very minor changes of strength after 90 days of water immersion. Leachability from the amalgam forms is also shown to be low: measured mercury concentration in the leachate by the Toxicity Characteristic Leaching Procedure (TCLP) was well below the Environmental Protection Agency (EPA) limit. Long term leaching behavior by Accelerated Leach Test (ALT) has shown that the leaching process was dominated by diffusion and the effective diffusion coefficient was quite low (around 10-19 cm2/sec). The mercury vapor concentration from the amalgam forms were reduced to a 20% level of that for elemental mercury and to one-hundredth after 3 months.

  12. An estimate for the rank of the intersection of subgroups in free amalgamated products of two groups with normal finite amalgamated subgroup

    SciTech Connect

    Zakharov, Alexander O

    2013-02-28

    We generalize the estimate for the rank of intersection of subgroups in free products of groups, proved earlier by Ivanov and Dicks (which is analogous to the Hanna Neumann inequality in free groups) to the case of free amalgamated products of groups with normal finite amalgamated subgroup. We also prove that the estimate obtained is sharp and cannot be further improved when the amalgamated product contains an involution. Bibliography: 11 titles.

  13. A study of high copper amalgams. IV. Formation of eta Cu-Sn (Cu6Sn5) crystals in a high copper dispersant amalgam matrix.

    PubMed

    Okabe, T; Mitchell, R J; Fairhurst, C W

    1979-03-01

    In an HCD amalgam, eta Cu-Sn crystals were found dispersed within gamma1 matrix areas. Previously, eta Cu-Sn phase was thought to form only as part of a reaction zone surrounding Ag-Cu dispersant particles. The eta Cu-Sn crystals found in matrix areas of this HCD amalgam are smaller and more widely scattered than eta Cu-Sn crystals dispersed in the gamma1 matrix of HCSC amalgams.

  14. Management of large radicular cyst associated with amalgam particles in cystic lining.

    PubMed

    Borkar, Swati A; Dhupar, Vikas; Gadkar, Abhilasha M; Nivedita, C K V S

    2016-01-01

    The failure of amalgam retrofilling and presence of an associated cystic lesion makes surgical endodontic intervention inevitable. Amalgam retrofilling can also give rise to mucoperiosteal tattoo formation and allow incorporation of amalgam particles in the cystic lining. Such a finding has not yet been reported in the endodontic literature. This case report describes the successful endodontic management of a large radicular cyst associated with failed amalgam retrofilling, mucoperiosteal tattoo and amalgam particles dispersed in the epithelial cystic lining. All four mandibular incisors associated with the lesion presented with Weine Type II canal anatomy. The follow-up revealed clinical and radiographic signs of healing.

  15. Dental Assistants

    MedlinePlus

    ... help keep the dental office running smoothly. Important Qualities Detail oriented. Dental assistants must follow specific rules and protocols, such as infection control procedures, when helping dentists treat patients. Assistants also ...

  16. Exploiting the higher specificity of silver amalgamation: selective detection of mercury(II) by forming Ag/Hg amalgam.

    PubMed

    Deng, Li; Ouyang, Xiangyuan; Jin, Jianyu; Ma, Cheng; Jiang, Ying; Zheng, Jing; Li, Jishan; Li, Yinhui; Tan, Weihong; Yang, Ronghua

    2013-09-17

    Heavy metal ion pollution poses severe risks in human health and the environment. Driven by the need to detect trace amounts of mercury, this article demonstrates, for the first time, that silver/mercury amalgamation, combining with DNA-protected silver nanoparticles (AgNPs), can be used for rapid, easy and reliable screening of Hg(2+) ions with high sensitivity and selectivity over competing analytes. In our proposed approach, Hg(2+) detection is achieved by reducing the mercury species to elemental mercury, silver atoms were chosen as the mercury atoms' acceptors by forming Ag/Hg amalgam. To signal fluorescently this silver amalgamation event, a FAM-labeled ssDNA was employed as the signal reporter. AgNPs were grown on the DNA strand that resulted in greatly quenching the FAM fluorescence. Formation of Ag/Hg amalgam suppresses AgNPs growth on the DNA, leading to fluorescence signal increase relative to the fluorescence without Hg(2+) ions, as well as marked by fluorescence quenching. This FAM fluorescence enhancement can be used for detection of Hg(2+) at the a few nanomolar level. Moreover, due to excellent specificity of silver amalgamation with mercury, the sensing system is highly selective for Hg(2+) and does not respond to other metal ions with up to millimolar concentration levels. This sensor is successfully applied to determination of Hg(2+) in tap water, spring water and river water samples. The results shown herein have important implications in the development of new fluorescent sensors for the fast, easy, and selective detection and quantification of Hg(2+) in environmental and biological samples.

  17. Exposures of dental professionals to elemental mercury and methylmercury.

    PubMed

    Goodrich, Jaclyn M; Chou, Hwai-Nan; Gruninger, Stephen E; Franzblau, Alfred; Basu, Niladri

    2016-01-01

    Mercury (Hg) exposure, a worldwide public health concern, predominantly takes two forms--methylmercury from fish consumption and elemental Hg from dental amalgam restorations. We recruited 630 dental professionals from an American Dental Association meeting to assess Hg body burden and primary sources of exposure in a dually exposed population. Participants described occupational practices and fish consumption patterns via questionnaire. Hg levels in biomarkers of elemental Hg (urine) and methylmercury (hair and blood) were measured with a Direct Mercury Analyzer-80 and were higher than the general US population. Geometric means (95% CI) were 1.28 (1.19-1.37) μg/l in urine, 0.60 (0.54-0.67) μg/g in hair and 3.67 (3.38-3.98) μg/l in blood. In multivariable linear regression, personal amalgams predicted urine Hg levels along with total years in dentistry, amalgams handled, working hours and sex. Fish consumption patterns predicted hair and blood Hg levels, which were higher among Asians compared with Caucasians. Five species contributed the majority of the estimated Hg intake from fish--swordfish, fresh tuna, white canned tuna, whitefish and king mackerel. When studying populations with occupational exposure to Hg, it is important to assess environmental exposures to both elemental Hg and methylmercury as these constitute a large proportion of total exposure.

  18. Exposures of Dental Professionals to Elemental Mercury and Methylmercury

    PubMed Central

    Goodrich, Jaclyn M.; Chou, Hwai-Nan; Gruninger, Stephen E.; Franzblau, Alfred; Basu, Niladri

    2015-01-01

    Mercury (Hg) exposure, a worldwide public health concern, predominantly takes two forms – methylmercury from fish consumption and elemental Hg from dental amalgam restorations. We recruited 630 dental professionals from an American Dental Association meeting to assess Hg body burden and primary sources of exposure in a dually-exposed population. Participants described occupational practices and fish consumption patterns via questionnaire. Mercury levels in biomarkers of elemental Hg (urine) and methylmercury (hair, blood) were measured with a Direct Mercury Analyzer-80 and were higher than the general U.S. population. Geometric means (95% CI) were 1.28 (1.19–1.37) µg/L in urine, 0.60 (0.54–0.67) µg/g in hair, and 3.67 (3.38–3.98) µg/L in blood. In multivariable linear regression, personal amalgams predicted urine Hg levels along with total years in dentistry, amalgams handled, working hours, and sex. Fish consumption patterns predicted hair and blood Hg levels which were higher among Asians compared with Caucasians. Five species contributed the majority of the estimated Hg intake from fish - swordfish, fresh tuna, white canned tuna, whitefish, and king mackerel. When studying populations with occupational exposure to Hg, it is important to assess environmental exposures to both elemental Hg and methylmercury as these constitute a large proportion of total exposure. PMID:26329138

  19. The Urban Dental Index: a Method for Measuring and Mapping Dental Health Disparities across Urban Areas.

    PubMed

    Coles, Emily; Kruger, Estie; Anjrini, Abed Aktam; Tennant, Marc

    2017-02-06

    The aim of this study was to create an Urban Dental Index (UDI) for Perth, Western Australia, adapting a method utilised by the World Health Organisation. Dental health indicators were derived from the 2011 census, standardised on a (0,1) interval, amalgamated using a geometric mean, and mapped to identify dental health inequity. The validity of the UDI was tested by comparison with oral cellulitis data. Dental health disparities were examined using a ratio of the mean of the highest to lowest decile and slope of the eight middle deciles. The robustness of the UDI was tested using indicator correlation, weighting, and systematic indicator removal. There were a high proportion of low UDI census areas outside the inner city. Adult public dental clinics were unevenly distributed across these low UDI areas. The UDI was significantly correlated with oral cellulitis data and had a moderate disparity ratio (1.69) and slope (0.23). All dental indicators were highly correlated, and UDIs calculated with weighted indicators and indicators removed were significantly correlated with the original UDI. These results indicate that the UDI is a robust tool which can be used by policy makers to target dental health initiatives to high-risk areas.

  20. [Root-end filling materials in apicoectomy--a review].

    PubMed

    Grossman, I; Abu el Naag, A; Peled, M

    2003-04-01

    An integral component of apicoectomy procedure is the placement of a root end filling material. In this 20 years literature review we identified at least 19 different materials that have been used as root end filling materials. Unfortunately, the ideal material for this purpose is yet to be found. Amalgam is the most frequently used material in apicoectomy procedure and can lead to satisfying results in many cases. IRM, super EBA and MTA are more suitable materials, and give better results in apicoectomy procedures than Amalgam. IRM and super EBA are both ZOE cements. Super EBA is less cytotoxic than IRM, suggesting that the decreased eugenol in Super EBA allows it to be less irritating. MTA gives better results when tested for leakage and biocompatibility than IRM and Super EBA, and has the ability of induction of hard tissue. A possible disadvantage that prevents MTA from being acceptable as "the ideal root-end filling material" is a long setting time that may lead to dislodgment or deformation from root end preparation. Yet, in most cases MTA serves as the best choice for a root end filling material.

  1. Dental OCT

    NASA Astrophysics Data System (ADS)

    Colston, Bill W.; Sathyam, Ujwal S.; Dasilva, Luiz B.; Everett, Matthew J.; Stroeve, Pieter; Otis, L. L.

    1998-09-01

    We present here the first in vivo optical coherence tomography (OCT) images of human dental tissue. A novel dental optical coherence tomography system has been developed. This system incorporates the interferometer sample arm and transverse scanning optics into a handpiece that can be used intraorally to image human dental tissues. The average imaging depth of this system varied from 3 mm in hard tissues to 1.5 mm in soft tissues. We discuss the application of this imaging system for dentistry and illustrate the potential of our dental OCT system for diagnosis of periodontal disease, detection of caries, and evaluation of dental restorations.

  2. Experimental oral foreign body reactions. Commonly employed dental materials.

    PubMed

    Stewart, C M; Watson, R E

    1990-06-01

    Foreign bodies and tissue reactions to foreign materials are commonly encountered in the oral cavity. The more common lesions include apical deposition of endodontic materials, mucosal amalgam and graphite tattoos, myospherulosis, oil granulomas, and traumatically introduced dental materials and instruments. Since many foreign materials are unidentifiable histologically, commonly used dental materials were experimentally implanted subcutaneously in rats to assess local host responses and characterize the nature of these materials microscopically. The histologic characteristics of these foreign body reactions are detailed herein. The implanted materials corresponded to reactions seen in human subjects.

  3. Measurements of Mercury Released from Amalgams and Sulfide Compounds

    SciTech Connect

    Mattus, C.H.

    1999-04-01

    This report covers work performed during FY 1998 in support of treatment demonstrations conducted for the Mercury Working Group. In order to comply with the requirements of the Resource Conservation and Recovery Act, as implemented by the US Environmental Protection Agency (EPA), the US Department of Energy (DOE) must apply amalgamation, the treatment standard for radioactively contaminated mercury, before disposing of these wastes. The Mercury Working Group under the Mixed Waste Focus Area sponsored a demonstration in which two commercial vendors demonstrated their technologies for the treatment of radioactive mercury from various DOE sites. The project, described in this report, addresses the need for data on the vapor pressure and degradation occurring in amalgamated mercury mixed low-level wastes generated during these demonstrations under a variety of conditions.

  4. Relationship between performance in dental school and performance on a dental licensure examination: an eight-year study.

    PubMed

    Stewart, Carol M; Bates, Robert E; Smith, Gregory E

    2005-08-01

    This study assessed relationships between academic performance in dental school and "first attempt" performance on a state dental licensure examination for 1996-2003 graduates from the University of Florida College of Dentistry (UFCD). The 524 graduates were ranked into quartiles based on graduating GPA. Using analysis of variance (ANOVA), the students' mean exam score (or exam section score) for each respective quartile (n=131) was compared with mean score for graduates in the combined four quartiles (n=524). ANOVA assessments, by quartile, were performed for the following six measures: 1) overall composite score on the dental licensure exam, 2) clinical periodontics section, 3) clinical amalgam section, 4) combination of clinical periodontics and clinical amalgam, 5) laboratory (manikin exam) with a written prosthodontic exam, and 6) manikin exam without the prosthodontic exam. For the overall exam and all exam sections, a significant (p<0.001) relationship was found between higher mean exam scores and academic ranking in quartile 1. A significant relationship was found between performance (lower mean scores) and ranking in quartile 4 for all exam sections, with the exception of the clinical periodontal section. The results of this study indicate a correlation between performance in dental school and performance on the Florida dental licensure exam for 1996-2003 UFCD graduates.

  5. A model for amalgamation in group decision making

    NASA Technical Reports Server (NTRS)

    Cutello, Vincenzo; Montero, Javier

    1992-01-01

    In this paper we present a generalization of the model proposed by Montero, by allowing non-complete fuzzy binary relations for individuals. A degree of unsatisfaction can be defined in this case, suggesting that any democratic aggregation rule should take into account not only ethical conditions or some degree of rationality in the amalgamating procedure, but also a minimum support for the set of alternatives subject to the group analysis.

  6. The effect of mucine, IgA, urea, and lysozyme on the corrosion behavior of various non-precious dental alloys and pure titanium in artificial saliva.

    PubMed

    Bilhan, H; Bilgin, T; Cakir, A F; Yuksel, B; Von Fraunhofer, J A

    2007-11-01

    The corrosion of dental alloys has biological, functional, and aesthetic consequences. Various studies have shown that protein solutions can inhibit the corrosion of alloys. This study is planned to determine the relationship of organic constituents of saliva and the corrosion of dental alloys. The organic constituents are IgA, mucine, urea, and lysozyme which are encountered in the highest amounts in saliva and the dental materials are titanium (Ti), Co-Cr-Mo and Ni-Cr-Mo alloys, and dental amalgam, the most often used metallic components in dentistry. In particular, the interactions between the commonest salivary proteins, IgA, mucine, urea and lysozyme, and Ti, Co-Cr-Mo, Ni-Cr-Mo and dental amalgam were investigated. Each alloy was evaluated by cyclic polarization in each medium. The general anodic and cathodic behavior during forward and reverse cycles, the corrosion and passivation current densities (muA/cm2 ), and the corrosion and the pitting potentials (mV) were determined. The results have shown that Ni-Cr-Mo and dental amalgam alloys are highly susceptible to corrosion in all the investigated media. The Co-Cr-Mo alloy has shown high passive current densities in the solution of mucine and lysozyme in artificial saliva. Titanium instead, has shown a high resistance to corrosion and a stable passive behavior in all media, especially in a solution of mucine and IgA in synthetic saliva. Mucine and IgA, as well as urea and lysozyme, appeared to enhance the formation of a passive film layer on the Ti metal surface, thus inhibiting the corrosion. Based on the study findings, and especially considering the problem of nickel allergy and toxicity of mercury released from dental amalgam, the use of Co-Cr-Mo alloys and Ti to Ni-Cr-Mo alloys is recommended and alternatives to dental amalgam should be sought for patients with impaired salivary flow.

  7. A Novel Characterization of Amalgamated Networks in Natural Systems

    PubMed Central

    Barranca, Victor J.; Zhou, Douglas; Cai, David

    2015-01-01

    Densely-connected networks are prominent among natural systems, exhibiting structural characteristics often optimized for biological function. To reveal such features in highly-connected networks, we introduce a new network characterization determined by a decomposition of network-connectivity into low-rank and sparse components. Based on these components, we discover a new class of networks we define as amalgamated networks, which exhibit large functional groups and dense connectivity. Analyzing recent experimental findings on cerebral cortex, food-web, and gene regulatory networks, we establish the unique importance of amalgamated networks in fostering biologically advantageous properties, including rapid communication among nodes, structural stability under attacks, and separation of network activity into distinct functional modules. We further observe that our network characterization is scalable with network size and connectivity, thereby identifying robust features significant to diverse physical systems, which are typically undetectable by conventional characterizations of connectivity. We expect that studying the amalgamation properties of biological networks may offer new insights into understanding their structure-function relationships. PMID:26035066

  8. Metal artifact reduction in dental CT images using polar mathematical morphology.

    PubMed

    Naranjo, Valery; Lloréns, Roberto; Alcañiz, Mariano; López-Mir, Fernando

    2011-04-01

    Most dental implant planning systems use a 3D representation of the CT scan of the patient under study as it provides a more intuitive view of the human jaw. The presence of metallic objects in human jaws, such as amalgam or gold fillings, provokes several artifacts like streaking and beam hardening which makes the reconstruction process difficult. In order to reduce these artifacts, several methods have been proposed using the raw data, directly obtained from the tomographs, in different ways. However, in DICOM-based applications this information is not available, and thus the need of a new method that handles this task in the DICOM domain. The presented method performs a morphological filtering in the polar domain yielding output images less affected by artifacts (even in cases of multiple metallic objects) without causing significant smoothing of the anatomic structures, which allows a great improvement in the 3D reconstruction. The algorithm has been automated and compared to other image denoising methods with successful results.

  9. Bond strength of resin composite to differently conditioned amalgam.

    PubMed

    Ozcan, M; Vallittu, P K; Huysmans, M-C; Kalk, W; Vahlberg, T

    2006-01-01

    Bulk fracture of teeth, where a part of the amalgam restoration and/or the cusp is fractured, is a common clinical problem. The aim of this study was to evaluate the effect of different surface conditioning methods on the shear bond strength of a hybrid resin composite to fresh amalgam. Amalgams (N=84) were condensed into acrylic and randomly assigned to one of the following treatments (N=6): (1) Alloy primer + opaquer, (2) Air-particle abrasion (50 micro m Al(2)O(3)) + alloy primer + opaquer, (3) Silica coating (30 micro m SiO(x)) + silanization + opaquer, (4) Opaquer + pre-impregnated continuous bidirectional E-glass fibre sheets, (5) Silica coating + silanization + fibre sheets, (6) Silica coating + silanization + opaquer + fibre sheet application. Non-conditioned amalgam surfaces were considered as control group (7). The mean surface roughness depth (R(Z)) was measured from the control group and air-abraded amalgam surfaces. The resin composite was bonded to the conditioned amalgam specimens using polyethylene molds. All specimens were tested under dry and thermocycled (6.000, 5-55 degrees C, 30 s) conditions. The shear bond strength of resin composite to amalgam substrates was measured in a universal testing machine (1 mm/min). Surface roughness values for the non-conditioned control group (R(Z) approximately 0.14 micro m) and for air-particle abraded surfaces with either Al(2)O(3) or SiO(x) (R(Z) approximately 0.19 micro m and R(Z) approximately 0.16 micro m, respectively) did not show significant differences (p=0.23) (One-way ANOVA). In dry conditions, silica coating and silanization followed by fibre sheet application exhibited significantly higher results (14.8+/-5.6 MPa) than those of the groups conditioned with alloy primer (2.2+/-0.7 MPa) (p<0.001), air-particle abrasion+alloy primer (4.4+/-2.0 MPa, p<0.001), silica coating+silanization alone (6.2+/-0.8 MPa, p=0.009) or non-conditioned group (1.4+/-0.6, p<0.001). Silica coating and silanization followed

  10. Dental sepsis.

    PubMed

    Mueller, P O; Lowder, M Q

    1998-08-01

    Dental sepsis or periapical abscess formation constitutes a large percentage of dental conditions that afflict horses. Dental sepsis occurs when the pulp chamber of the tooth is exposed to the oral cavity or external environment, allowing bacterial localization with resulting infection. Although acute, primary, septic pulpitis in horses is rare, dental sepsis often results from colonization of the pulp chamber with pathogenic bacteria secondary to maleruption or impaction of teeth with secondary alveolar bone lysis, primary fractures of the tooth, mandible, or maxilla, periodontal disease, or infundibular necrosis. The sequela to pulpal infection are extensions into the periradicular tissues and mandibular or maxillary periapical abscess formation.

  11. The Level of Dental Anxiety and Dental Status in Adult Patients

    PubMed Central

    Dobros, Katarzyna; Hajto-Bryk, Justyna; Wnek, Anna; Zarzecka, Joanna; Rzepka, Dominik

    2014-01-01

    Background: The present study aimed to assess potential correlation between dental anxiety and overall dental status in adult patients, in consideration of the frequency of dental appointments and individual dental hygiene practices. Materials and Methods: Individual dental anxiety levels were assessed with the aid of the Corah’s dental anxiety scale (DAS). The study embraced 112 patients of the University Dental Clinic, Kraków. Following clinical and X-ray exams, respectively, decayed, missing and filled teeth (DMFT) index and dental treatment index (DTI) were computed for each study subject. Results: Mean DAS among the 112 subjects under study was 9.41 standard deviation (SD = 3.36). Mean DMFT value was 15.86 (SD = 7.00), whereas DTI value was 0.76 (SD = 0.27). The number of decayed teeth and an individual dental anxiety level were found to be correlated (r = 0.26). Higher dental anxiety correlated with lower DTI value (r = −0.22) and lesser frequency of dental appointments (r = 0.22). Conclusions: Individual dental anxiety level appears to impact overall dental status, frequency of dental appointments and everyday oral health practices. Every conceivable effort should therefore be undertaken with a view to effectively diminishing dental anxiety levels in the patients. How to cite the article: Dobros K, Hajto-Bryk J, Wnęk A, Zarzecka J, Rzepka D. The level of dental anxiety and dental status in adult patients. J Int Oral Health 2014;6(3):11-4. PMID:25083026

  12. A 3-year randomized clinical trial evaluating two different bonded posterior restorations: Amalgam versus resin composite

    PubMed Central

    Kemaloglu, Hande; Pamir, Tijen; Tezel, Huseyin

    2016-01-01

    Objective: To compare the performance and postoperative sensitivity of a posterior resin composite with that of bonded amalgam in 40 (n = 20) large sized cavities and to evaluate whether resin composite could be an alternative for bonded amalgam. Materials and Methods: This was a randomized clinical trial. Twenty patients in need of at least two posterior restorations were recruited. Authors randomly assigned one half of the restorations to receive bonded amalgam and the other half to composite restorations. Forty bonded amalgams (n = 20) and composites (n = 20) were evaluated for their performance on modified-US Public Health Service criteria and postoperative sensitivity using visual analogue scale (VAS) for 36-months. Results: Success rate of this study was 100%. First clinical alterations were rated as Bravo after 1 year in marginal discoloration, marginal adaptation, anatomical form, and surface roughness for both amalgam and composite. At the 3rd year, overall “Bravo” rated restorations were 12 for bonded amalgam and 13 for resin composites. There were no significant differences among the VAS scores of composites and bonded amalgams for all periods (P > 0.05) except for the comparisons at the 3rd year evaluation (P < 0.05). Conclusions: Within the limitation of this study, both resin composite and bonded amalgam were clinically acceptable. Postoperative sensitivity results tend to decrease more in composite restorations rather than amalgams. Therefore, it was concluded that posterior resin composite can be used even in large sized cavities. PMID:27011734

  13. A Review of Mercury Exposure and Health of Dental Personnel.

    PubMed

    Nagpal, Natasha; Bettiol, Silvana S; Isham, Amy; Hoang, Ha; Crocombe, Leonard A

    2017-03-01

    Considerable effort has been made to address the issue of occupational health and environmental exposure to mercury. This review reports on the current literature of mercury exposure and health impacts on dental personnel. Citations were searched using four comprehensive electronic databases for articles published between 2002 and 2015. All original articles that evaluated an association between the use of dental amalgam and occupational mercury exposure in dental personnel were included. Fifteen publications from nine different countries met the selection criteria. The design and quality of the studies showed significant variation, particularly in the choice of biomarkers as an indicator of mercury exposure. In several countries, dental personnel had higher mercury levels in biological fluids and tissues than in control groups; some work practices increased mercury exposure but the exposure levels remained below recommended guidelines. Dental personnel reported more health conditions, often involving the central nervous system, than the control groups. Clinical symptoms reported by dental professionals may be associated with low-level, long-term exposure to occupational mercury, but may also be due to the effects of aging, occupational overuse, and stress. It is important that dental personnel, researchers, and educators continue to encourage and monitor good work practices by dental professionals.

  14. Dental Hygienist.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document, which is designed for use in developing a tech prep competency profile for the occupation of dental hygienist, lists technical competencies and competency builders for 13 units pertinent to the health technologies cluster in general and 9 units specific to the occupation of dental hygienist. The following skill areas are covered in…

  15. Dental Implants.

    PubMed

    Zohrabian, Vahe M; Sonick, Michael; Hwang, Debby; Abrahams, James J

    2015-10-01

    Dental implants restore function to near normal in partially or completely edentulous patients. A root-form implant is the most frequently used type of dental implant today. The basis for dental implants is osseointegration, in which osteoblasts grow and directly integrate with the surface of titanium posts surgically embedded into the jaw. Radiologic assessment is critical in the preoperative evaluation of the dental implant patient, as the exact height, width, and contour of the alveolar ridge must be determined. Moreover, the precise locations of the maxillary sinuses and mandibular canals, as well as their relationships to the site of implant surgery must be ascertained. As such, radiologists must be familiar with implant design and surgical placement, as well as augmentation procedures utilized in those patients with insufficient bone in the maxilla and mandible to support dental implants.

  16. Allergic Reactions to Dental Materials-A Systematic Review

    PubMed Central

    Chopra, Radhika; Sachdev, Vinod

    2015-01-01

    Introduction Utility of various dental materials ranging from diagnosis to rehabilitation for the management of oral diseases are not devoid of posing a potential risk of inducing allergic reactions to the patient, technician and dentist. This review aims to develop a systematic approach for the selection and monitoring of dental materials available in the market thereby giving an insight to predict their risk of inducing allergic reactions. Materials and Methods Our data included 71 relevant articles which included 60 case reports, 8 prospective studies and 3 retrospective studies. The source of these articles was Pub Med search done with the following terms: allergies to impression materials, sodium hypochlorite, Ledermix paste, zinc oxide eugenol, formaldehyde, Latex gloves, Methyl methacrylate, fissure sealant, composites, mercury, Nickel-chromium, Titanium, polishing paste and local anaesthesia. All the relevant articles and their references were analysed. The clinical manifestations of allergy to different dental materials based on different case reports were reviewed. Results After reviewing the literature, we found that the dental material reported to cause most adverse reactions in patients is amalgam and the incidence of oral lichenoid reactions adjacent to amalgam restorations occur more often than other dental materials. Conclusion The most common allergic reactions in dental staff are allergies to latex, acrylates and formaldehyde. While polymethylmethacrylates and latex trigger delayed hypersensitivity reactions, sodium metabisulphite and nickel cause immediate reactions. Over the last few years, due to the rise in number of patients with allergies from different materials, the practicing dentists should have knowledge about documented allergies to known materials and thus avoid such allergic manifestations in the dental clinic. PMID:26557634

  17. Rondeau Seminars amalgamated mid-sagittal (lateral) cephalometric analysis.

    PubMed

    Palencar, Adrian J

    2014-01-01

    The author presents a comprehensive International Association for Orthodontics--Rondeau Seminars Amalgamated Mid-sagittal (Lateral) Cephalometric Analysis. Norms on the Cephalometric Data Sheet are age and gender specific for the Caucasian population and the postings are color coded for visual attraction. If the patient is ofa different ethnic group, the Norms should be adjusted accordingly. This Cephalometric Analysis is comprised often Sections, in alphabetical order and twenty nine Factors. The author expanded Rondeau Seminars Cephalometric Analysis by only six Factors, thus fulfilling the requirement for the case presentation for the Fellow of the IAO and the Diplomate ofthe IBO.

  18. EDS and μ-XRF mapping of amalgam degradation products in ancient mirrors.

    PubMed

    Arizio, E; Orsega, E F; Falcone, R; Vallotto, M

    2014-12-01

    An amalgam mirror is a mirror type, used from the fifteenth century until the end of the nineteenth century, where the reflective layer is constituted by a tin amalgam layer adhered to a glass sheet. In this work, two amalgam mirrors samples were studied by scanning electron microscopy with an energy dispersive spectrometer and by micro-X-ray fluorescence elemental mapping to go deeply into the understanding of the degradation mechanism of the amalgam layer of ancient mirrors. The investigation has been focused for the first time on the reflective surface of the amalgam layer adherent to the glass sheet to better understand the processes of amalgam corrosion. The two amalgam degradation compounds, romarchite and cassiterite, has been spatially differentiated by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) maps. SEM images and micro-X-ray fluorescence and EDS maps showed that the amalgam degradation products grow up to form hemispherical stratified calottes. This structure is probably due to a mechanism involves cyclic phases and oxygen radial diffusion from a superficial oxidation nucleus.

  19. Tin amalgam mirrors: investigation by XRF, SEM-EDS, XRD and EPMA-WDS mapping

    NASA Astrophysics Data System (ADS)

    Arizio, E.; Orsega, E. F.; Sommariva, G.; Falcone, R.

    2013-06-01

    Ancient mirrors were constituted by a tin-mercury amalgam layer superimposed to a glass sheet. This was the only one method used until the nineteenth century, when the wet silvering process was invented. The tin amalgam is a binary alloy of tin and mercury constituted by two different phases: a mercury-rich liquid phase and a tin-rich solid phase. The amalgam alteration produces mercury loss and a general growth of the solid crystalline phase. In addition, tin dioxide and monoxide are formed with a consequent decrease of the amalgam adhesion to the glass. These degradation phenomena led to reduction or disappearance of the mirror reflective power. The aim of this study was the characterization of the amalgam layers of eight mirror samples dating during the seventeenth and nineteenth centuries. The samples were analyzed by X-ray diffraction and by a Scanning Electron Microscope with an Energy Dispersive Spectrometer (SEM-EDS), and for the first time on this type of alloy by X-ray Fluorescence and EPMA-WDS (Electron Probe Micro Analysis with Wavelength Dispersive Spectrometry) elemental mapping. The contents of tin, mercury, and some trace elements in the amalgam layers have been determined. The investigation of the superficial patterns of the amalgam by SEM, EPMA-WDS mapping, and SEM-EDS allowed a first understanding of some morphologies and processes of the degradation of the amalgam layer.

  20. An elementary study of deformation of molar teeth during amalgam restorative procedures.

    PubMed

    Bell, J G

    1977-06-01

    A technique using an optical comparator was employed to examine the dimensional changes resulting from cavity preparation, application of the matrix and packing with amalgam in three extracted molar teeth. The changes have been reported and the nature of the change discussed. A modification in the use of the matrix and amalgam packing technique is suggested.

  1. Dental OCT

    NASA Astrophysics Data System (ADS)

    Wilder-Smith, Petra; Otis, Linda; Zhang, Jun; Chen, Zhongping

    This chapter describes the applications of OCT for imaging in vivo dental and oral tissue. The oral cavity is a diverse environment that includes oral mucosa, gingival tissues, teeth and their supporting structures. Because OCT can image both hard and soft tissues of the oral cavity at high resolution, it offers the unique capacity to identity dental disease before destructive changes have progressed. OCT images depict clinically important anatomical features such as the location of soft tissue attachments, morphological changes in gingival tissue, tooth decay, enamel thickness and decay, as well as the structural integrity of dental restorations. OCT imaging allows for earlier intervention than is possible with current diagnostic modalities.

  2. Copper release from dental prosthetic crowns, dental materials, and human teeth into acetic acid.

    PubMed

    Kalicanin, Biljana M; Nikolić, Ruzica S

    2010-01-01

    This article examines the dilution of the ion of copper from human teeth and dental prosthetic crowns in 4% CH(3)COOH during a period of 24 hr at room temperature. The content of the diluted copper in an acetate extract, as well as the overall content of this metal in the samples, was determined by means of a potentiometric stripping analysis. The comparative measurements were carried out using the furnace atomic absorption spectrophotometry technique, which is recommended by the International Standards (ISO 6872:2008; ISO 24234:2004) as a method for quality control of dental-prosthetic material (dental ceramic, metal restorative materials, dental amalgams) in the process of checking for heavy metals. During a 24-hr period in 4% CH(3)COOH at a temperature of 25 degrees C, approximately 72% of the overall copper was released from the tooth. The percentage of the released copper from baby teeth is higher, ranging from 88 to 92%, which is probably a consequence of the bone tissue being in development, its infirmity, and inadequate stability. On these conditions, approximately 72% of the overall copper was released from the dental-ceramic prosthetic crowns.

  3. Getting a prescription filled

    MedlinePlus

    ... prescription filled; Drugs - how to get prescription filled; Pharmacy - mail order; Pharmacy - internet; Types of pharmacies ... paper prescription that you take to a local pharmacy Calling or e-mailing a pharmacy to order ...

  4. Registered Dental Hygienists as Dental Students.

    ERIC Educational Resources Information Center

    Arnold, Janet; Shugars, Daniel A.

    1985-01-01

    Surveys conducted to (1) investigate why dental hygienists choose to become dentists, (2) evaluate their success in dental school, (3) assess the experience of those who had entered dental school, and (4) gauge the level of interest among dental hygienists in applying to dental school are discussed. (Author/MLW)

  5. Mercury as a potential hazard for the dental practitioner.

    PubMed

    Kostyniak, P J

    1998-04-01

    Mercury has been used for centuries for medical, chemical, metallurgical and electrical applications. It is an element of mystery, which in its metallic form is an enticing silvery liquid that can be as fascinating as it is dangerous. Its use in dental amalgam has a potential for continuous occupational exposure of dental practitioners to mercury vapor. It is imperative that the dental practitioner understands the hazards associated with the use of mercury, and controls exposures to prevent the development of any untoward effects. This article provides an overview of the toxicology of the different forms of mercury to which human exposure occurs and addresses safety issues associated with mercury vapor, the primary form of mercury encountered in the practice of dentistry.

  6. Dental sealants

    MedlinePlus

    ... few quick steps. There is no drilling or scraping of the molars. Your dentist will: Clean the ... Dental sealants. Updated October 19, 2016. ADA.org Web site. www.ada.org/en/member-center/oral- ...

  7. Dental Sealants

    MedlinePlus

    ... form does not collect any actual information. External Web Site Policy This graphic notice ( ) means that you are ... the link. Home Contact Us Viewers and Players Site Map FOIA Web Policies Privacy Policy National Institute of Dental and ...

  8. 75 FR 16511 - Pentron Clinical Technologies, a Wholly-Owned Subsidiary of Kerr Dental/Sybron Dental...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-01

    ... such as dental prosthetics, dental composites, dental impressions, dental adhesives, and other dental... prosthetics, dental composites, dental impressions, dental adhesives, and other dental materials to...

  9. Galvanic corrosion and cytotoxic effects of amalgam and gallium alloys coupled to titanium.

    PubMed

    Bumgardner, J D; Johansson, B I

    1996-06-01

    The aim of this study was to examine and compare the galvanic corrosion of a conventional, a dispersed high-copper, and a palladium-enriched spherical high-copper amalgam and a gallium alloy coupled to titanium in saline and cell culture solutions, and to evaluate the effects of the couples on cultured cells. The potentials and charge transfers between amalgams and titanium were measured by electrochemical corrosion methods. Cytotoxicity of the couples, as indicated by the uptake of neutral red vital stain, was determined in 24-h direct contact human gingival fibroblast cell cultures. Results of this study indicated that before connecting the high-copper amalgams to titanium, the amalgams exhibited more positive potentials which resulted in initial negative charge transfers, i.e. corrosion of titanium. However, this initial corrosion appeared to cause titanium to passivate, and a shift in galvanic currents to positive charge transfers, i.e. corrosion of the amalgam samples. Lower galvanic currents were measured for the amalgam-titanium couples as compared to the gallium alloy-titanium couple. Coupling the conventional or the palladium-enriched high-copper amalgams to titanium did not significantly affect the uptake of neutral red as compared to cells not exposed to any test alloy. However, significant cytotoxic effects were observed when the dispersed-type high-copper amalgam and the gallium alloy were coupled to titanium. Even though the corrosion currents measured for these couples were less than gold alloys coupled to amalgam, these results suggest there is the potential for released galvanic corrosion products to become cytotoxic. These data warrant further investigations into the effects of coupling amalgam and gallium alloys to titanium in the oral environment.

  10. In vivo and in vitro evaluations of microleakage around Class I amalgam and composite restorations.

    PubMed

    Alptekin, Tuncay; Ozer, Fusan; Unlu, Nimet; Cobanoglu, Nevin; Blatz, Markus B

    2010-01-01

    This study evaluated and compared microleakage values of in vivo and in vitro placed Class I amalgam restorations with or without three different lining materials and posterior composite restorations with two dentin bonding agents. For the in vivo group, 72 standardized Class I cavities were prepared on the occlusal surfaces of molars scheduled for extraction. The test groups (n = 12) were: amalgam without lining (A), amalgam with cavity varnish (A+C), amalgam with Clearfil SE Bond (A+CSE), amalgam with Clearfil 2V (A+C2V), composite with Clearfil SE Bond (C+CSE) and composite with Protect Bond (C+PB). The restored teeth were extracted after seven days. The same grouping, materials and techniques were used in 72 extracted molars for the in-vitro part of the study. The specimens were immersed in basic fuchsin for 24 hours and sectioned. Microleakage was examined and scored at 20x magnification. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney U-tests with the 5% level of significance. Overall, the in vivo and in vitro test groups were not different from each other. No significant differences in microleakage values were observed between the unlined and lined amalgam groups (p > 0.05). However, since lined amalgam restorations did not reveal any marginal leakage, the application of an adhesive bonding material under the amalgam restorations can be considered. In general, cavity varnish was not as effective as adhesive bonding agents in preventing microleakage in amalgam restorations. Composite restorations demonstrated higher leakage values than amalgam restorations (p < 0.05), except for A+C (p > 0.05) in the in vivo group. There was no significant difference between the two composite groups for in vitro and in vivo conditions (p > 0.05).

  11. Three-body wear of a hand-consolidated silver alternative to amalgam.

    PubMed

    Xu, H H; Eichmiller, F C; Giuseppetti, A A; Ives, L K; Parry, E E; Schumacher, G E

    1999-09-01

    Recent studies have investigated a mercury-free silver alternative to amalgam, but the silver powders required a relatively high compaction pressure to consolidate. The aim of the present study was to consolidate a precipitated silver powder into a cohesive solid using an air-driven pneumatic condenser fitted with an amalgam plugger at a clinically realistic load, and to study the mechanisms and rates of three-body wear of the consolidated silver in comparison with that of an amalgam. The silver powder was annealed, rinsed with a dilute acid, and consolidated either in a prepared tooth cavity or in a specimen mold at a load of 15 N. A four-station wear machine was used where each specimen was immersed in a slurry containing polymethyl methacrylate beads, then a steel pin was loaded and rotated against the specimen at a maximum load of 76 N. The flexural strength in MPa (mean +/- SD; n = 10) was 86 +/- 20 for amalgam, 181 +/- 45 for silver with a polished surface, and 202 +/- 21 for silver with a burnished surface. After 4 x 10(5) wear cycles, the wear scar depth in microm was 134 +/- 54 for amalgam, 143 +/- 8 for polished silver, and 131 +/- 9 for burnished silver, which were not significantly different (Tukey's multiple comparison test; family confidence coefficient = 0.95). SEM examination revealed cracks and fracture pits in the worn surface of amalgam, in contrast to a smooth surface in silver. Wear and material removal in amalgam occurred by microfracture and dislodgement of cracked segments, while wear in the silver occurred by ductile deformation and flow of materials. To conclude, the consolidated silver possesses a three-body wear resistance similar to that of amalgam, and a higher resistance to wear-induced damage and cracking than amalgam. The mechanism of wear in amalgam is microfracture and material dislodgement, while that in consolidated silver is ductile deformation and flow of material.

  12. A Comparison of US and Japanese Dental Restorative Care Present on Service Members Recovered from the WWII Era.

    PubMed

    Shiroma, Calvin Y

    2017-02-20

    The documentation of dental materials used in the USA during the WWII era is readily available, while references for the Japanese are minimal. It was therefore important to build a photographic database of Japanese restorative care which could be utilized as a comparison tool for the deployed odontologist. The dental restorative care of approximately 400 US and 100 Japanese sets of remains was evaluated. Both countries share many similar restorative techniques to include collared crowns, full-coverage restorations, cantilever bridge/pontics to close spaces; restorative materials such as amalgam, gold, and zinc phosphate (temporary) restorations; and removable prostheses. The dental restorative materials most commonly used by US dentists include the amalgam and silicate cement, while the full-coverage crown was the type of restoration most frequently seen on the Japanese remains. Silicates, porcelain and replaceable crowns, and partial-coverage prepared crowns were not observed on the recovered Japanese remains.

  13. Do Laboratory Results Concerning High-Viscosity Glass-Ionomers versus Amalgam for Tooth Restorations Indicate Similar Effect Direction and Magnitude than that of Controlled Clinical Trials? - A Meta-Epidemiological Study

    PubMed Central

    Mickenautsch, Steffen; Yengopal, Veerasamy

    2015-01-01

    Background A large percentage of evidence concerning dental interventions is based on laboratory research. The apparent wealth of laboratory evidence is sometimes used as basis for clinical inference and recommendations for daily dental practice. In this study two null-hypotheses are tested: whether trial results from laboratory and controlled clinical trials concerning the comparison of high-viscosity glass-ionomer cements (HVGIC) to amalgam for restorations placed in permanent posterior teeth have: (i) similar effect direction and (ii) similar effect magnitude. Methods 7 electronic databases were searched, as well as reference lists. Odds ratios (OR) and Standardised Mean Differences (SMD) with 95% Confidence intervals were computed for extracted dichotomous and continuous data, respectively. Pooled effect estimates for laboratory and clinical data were computed to test for effect direction. Odds ratios were converted into SMDs. SMDs from laboratory and clinical data were statistically compared to test for differences in effect magnitude. The analysed results were further investigated within the context of potential influencing or confounding factors using a Directed acyclic graph. Results Of the accepted eight laboratory and nine clinical trials, 13 and 21 datasets could be extracted, respectively. The pooled results of the laboratory datasets were highly statistically significant in favor of amalgam. No statistically significant differences, between HVGICs and amalgam, were identified for clinical data. For effect magnitude, statistically significant differences between clinical and laboratory trial results were found. Both null-hypotheses were rejected. Conclusion Laboratory results concerning high-viscosity glass-ionomers versus amalgam for tooth restorations do not indicate similar effect direction and magnitude than that of controlled clinical trials. PMID:26168274

  14. Dental Emergencies

    PubMed Central

    Symington, J.M.

    1988-01-01

    Patients with dental emergencies sometimes present to their physician. This article outlines the role of the physician in the management of dental patients who have suffered traumatic injuries, postoperative hemorrhage, pain, and infection. It deals with those difficulties for which the physician may easily prescribe treatment and outlines the treatment that would be undertaken by a dentist who receives such a patient on referral. PMID:21253249

  15. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Identification. A dental handpiece and accessories is an AC-powered, water-powered, air-powered, or belt-driven... restorations, such as fillings, and for cleaning teeth. (b) Classification. Class I....

  16. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Identification. A dental handpiece and accessories is an AC-powered, water-powered, air-powered, or belt-driven... restorations, such as fillings, and for cleaning teeth. (b) Classification. Class I....

  17. Biocompatibility of a flowable composite bonded with a self-etching adhesive compared with a glass lonomer cement and a high copper amalgam.

    PubMed

    Shimada, Yasushi; Seki, Yuichi; Sasafuchi, Yasutaka; Arakawa, Makoto; Burrow, Michael F; Otsuki, Masayuki; Tagami, Junji

    2004-01-01

    This study evaluated the pulpal response and in-vivo microleakage of a flowable composite bonded with a self-etching adhesive and compared the results with a glass ionomer cement and amalgam. Cervical cavities were prepared in monkey teeth. The teeth were randomly divided into three groups. A self-etching primer system (Imperva FluoroBond, Shofu) was applied to the teeth in one of the experimental groups, and the cavities were filled with a flowable composite (SI-BF-2001-LF, Shofu). In the other groups, a glass ionomer cement (Fuji II, GC) or amalgam (Dispersalloy, Johnson & Johnson) filled the cavity. The teeth were then extracted after 3, 30 and 90 days, fixed in 10% buffered formalin solution and prepared according to routine histological techniques. Five micrometer sections were stained with hematoxylin and eosin or Brown and Brenn gram stain for bacterial observation. No serious inflammatory reaction of the pulp, such as necrosis or abscess formation, was observed in any of the experimental groups. Slight inflammatory cell infiltration was the main initial reaction, while deposition of reparative dentin was the major long-term reaction in all groups. No bacterial penetration along the cavity walls was detected in the flowable composite or glass ionomer cement except for one case at 30 days in the glass ionomer cement. The flowable composite bonded with self-etching adhesive showed an acceptable biological com- patibility to monkey pulp. The in vivo sealing ability of the flowable composite in combination with the self-etching adhesive was considered comparable to glass ionomer cement. Amalgam restorations without adhesive liners showed slight bacterial penetration along the cavity wall.

  18. Comparison of Gutta Percha Filling Techniques. Part 2. Three Chloroform-Gutta Percha Filling Techniques.

    DTIC Science & Technology

    1980-06-01

    Inlo Di-5r7W~f~ IU* Report) DTIC illE LECTE f_ IS. KEY WORDS (Conthue on revere* side It necessay and Identify by block numbei) -. , endodontics ...TECHNIQUES. PART 2: THREE CHLOROFORM-GUTTA PERCHA FILLING TECHNIQUES M. Wong, DDS Resident, Endodontics Dept. of Dentistry - PO Box 59 Madigan Army Medical...Center Tacoma, Washington 98431 D. 0. Peters, BA, DDS, MS Mentor, Endodontics US Army Institute of Dental Research Walter Reed Army Medical Center

  19. [Is amalgam stained dentin a proper substrate for bonding resin composite?].

    PubMed

    Scholtanus, J D

    2016-06-01

    After the removal of amalgam restorations, black staining of dentin is often observed, which is attributed to the penetration of corrosion products from amalgam. A study was carried out to determine whether this amalgam stained dentin is a proper substrate for bonding resin composites. A literature study and an in vitro study showed that Sn and Zn in particular are found in amalgam stained dentin, and this was the case only in demineralised dentin. In vitro, demineralised dentin acted as porte d'entrÈe for amalgam corrosion products. Bond strength tests with 5 adhesive strategies showed no differences between bond strengths to amalgam stained and to sound dentin, but did show different failure types. A clinical study showed good survival of extensive cusp replacing resin composite restorations. No failures were attributed to inadequate adhesion. It is concluded that staining of dentin by amalgam corrosion products has no negative effect upon bond strength of resin composite. It is suggested that Sn and Zn may have a beneficial effect upon dentin, thus compensating the effects of previous carious attacks, preparation trauma and physico-chemical challenges during clinical lifetime.

  20. Secondary Caries Development in in situ Gaps next to Composite and Amalgam.

    PubMed

    Kuper, Nicolien K; Montagner, Anelise F; van de Sande, Françoise H; Bronkhorst, Ewald M; Opdam, Niek J M; Huysmans, Marie-Charlotte D J N M

    2015-01-01

    This in situ study investigated the secondary caries development in dentin in gaps next to composite and amalgam. For 21 days, 14 volunteers wore a modified occlusal splint containing human dentin samples with an average gap of 215 µm (SD=55 µm) restored with three different materials: Filtek Supreme composite, Clearfil AP-X composite and Tytin amalgam. Eight times a day, the splint with samples was dipped in a 20% sucrose solution for 10 min. Before and after caries development, specimens were imaged with transversal wavelength independent microradiography, and lesion depth (LD) and mineral loss (ML) were calculated. The LD and ML of the three restoration materials were compared within patients using paired t tests (α=5%). In total 38 composite samples (Filtek n=19 and AP-X n=19) and 19 amalgam samples could be used for data analysis. AP-X composite presented the highest mean values of LD and ML of the three restorative materials. Amalgam showed statistically significantly less ML (Δ=452 µm×vol%) than the combined composite materials (p=0.036). When comparing amalgam to the separate composite materials, only AP-X composite showed higher ML (Δ=515 µm×vol%) than amalgam (p=0.034). Analysis of LD showed the same trends, but these were not statistically significant. In conclusion, amalgam showed reduced secondary caries progression in dentin in gaps compared to composite materials tested in this in situ model.

  1. Comparison of shear bond strength of amalgam bonded to primary and permanent dentin.

    PubMed

    Mahdi, S; Bahman, S; Arghavan, A B; Fatemeh, M

    2008-06-01

    Amalgam's non-adhesive characteristics necessitate cavity preparations incorporating retentive features, which often require the removal of non-carious tooth structure. Use of adhesives beneath amalgam restorations, would be helpful to overcome this disadvantage. This study was undertaken to compare the mean shear bond strength of amalgam bonded to primary and permanent dentin, to evaluate the efficacy of amalgam adhesives in pediatric dentistry.27 primary and 28 permanent posterior teeth with intact buccal or lingual surfaces were grounded to expose dentin and wet-polished with 400-grit silicone carbide paper. Scotchbond Multi Purpose Plus adhesive system was applied to the dentin surfaces and light cured. Amalgam was condensed onto the treated dentin through a plastic mold.shear bond strength testing was done using an Instron Universal testing machine, at a crosshead speed of 0.5 mm/min.The data were analyzed by independent samples t-test The difference among the two groups was not statistically significant (p>0.05) Bonded amalgam showed the same level of bond strength to primary and permanent dentin; so, application of amalgam bonding agents in pediatric dentistry can be recommended.

  2. Bonded amalgam restorations: using a glass-ionomer as an adhesive liner.

    PubMed

    Chen, R S; Liu, C C; Cheng, M R; Lin, C P

    2000-01-01

    Due to the lack of adhesiveness of amalgam to tooth structure, several adhesive cements have been utilized in bonded amalgam restorations. This study evaluated whether Fuji-II glass-ionomer cement is an appropriate adhesive liner in bonded amalgam restorations. Two adhesive composite luting cements (Amalgambond Plus and Panavia-21) and Copalite cavity liner were compared. The study was conducted in two phases. In the first part, we quantitatively assessed the tensile bond strengths as well as the failure modes of amalgam bonded to human dentin, using different adhesive liners. In each group, the flat dentin surface was treated with the assigned adhesive cement with a Teflon mold, followed by condensation of amalgam (Valiant PhD) onto it. Each group's mean tensile bond strengths were recorded and the statistical analysis by one way ANOVA showed no significant differences among groups (p > 0.05). Similar to the fracture patterns of the Amalgambond Plus and Panavia-21 groups, the failure mode of Fuji-II group was predominantly adhesive fracture. In the second part, the fracture strengths of amalgam restored teeth were measured using different adhesive liners. Standard MOD cavities were prepared in each tooth except for the intact tooth group. After treatment with the assigned adhesives or varnish, the cavities were restored with amalgam. Fracture strengths were then measured and the fractured interfaces examined using a scanning electron microscope. The fracture strengths of the intact tooth, Amalgambond Plus, Panavia-21 and Fuji-II groups were significantly higher than those of the Copalite and prepared cavity without restoration groups (p < 0.01). Accordingly, Fuji-II glass-ionomer cement, when used as an adhesive liner of amalgam restoration, may effectively reinforce the remaining tooth structure and, therefore, enhance the fracture resistance of the amalgam-restored teeth.

  3. A System Approach to Navy Medical Education and Training. Appendix 13. Dental Technician.

    DTIC Science & Technology

    1974-08-31

    IREMOVAL OF SALIVARY CALCULUS ISTONE) CIRCULATE 43 IREPAIR OF CONGENITAL ORTHODONTIC DEFECTS SCRUB 44 IREPAIR OF CONGENITAL ORTHODONTIC DEFECTS CIRCULATE...EXCAVATED CAVITY 40 IINSERT PULP CAP INTO EXCAVATEO CAVITY 41 IINSERT AMALGAM INTO EXCAVATED CAVITY 42 ICARVE AND RESTORE ANATOMICAL LANDMARKS ON DENTAL...REMOVE WAX FROM THE MOULD I. 42 IDE-FLASK DENTURES 43 IPACK FLASK WITH ACRYLIC RESIN 44 IFABRICATE OCCLUSION RIMS 45 IFABRICATE ORTHODONTIC APPLIANCE

  4. Dental surgery in ancient Egypt.

    PubMed

    Blomstedt, Patric

    2013-01-01

    Many different surgical procedures have over the years been attributed to the ancient Egyptians. This is also true regarding the field of dental surgery. The existence of dentists in ancient Egypt is documented and several recipes exist concerning dental conditions. However, no indications of dental surgery are found in the medical papyri or in the visual arts. Regarding the osteological material/mummies, the possible indications of dental surgery are few and weak. There is not a single example of a clear tooth extraction, nor of a filling or of an artificial tooth. The suggested examples of evacuation of apical abscesses can be more readily explained as outflow sinuses. Regarding the suggested bridges, these are constituted of one find likely dating to the Old Kingdom, and one possibly, but perhaps more likely, dating to the Ptolemaic era. Both seem to be too weak to have served any possible practical purpose in a living patient, and the most likely explanation would be to consider them as a restoration performed during the mummification process. Thus, while a form of dentistry did certainly exist in ancient Egypt, there is today no evidence of dental surgery.

  5. Dental Caries

    PubMed Central

    Burgess, Ralph C.

    1988-01-01

    Dental caries is one of the most prevalent diseases afflicting mankind. It reached a peak in the 1950s but has been declining drastically in recent years in children and young adults. This article describes the three contributing factors in dental caries: microbial plaque, tooth susceptibility, and diet, and discusses practical preventive measures which help to reduce caries incidence. Some of these, such as vaccines and antimicrobial varnishes, are still in the research stages, while others, such as sucrose substitutes, low-calorie sweeteners, and limitation of frequency of sugar snacks are well established and can be promoted by family physicians. PMID:21253193

  6. Biocompatibility of root-end filling materials: recent update

    PubMed Central

    Gupta, Saurabh Kumar; Newaskar, Vilas

    2013-01-01

    The purpose of a root-end filling is to establish a seal between the root canal space and the periradicular tissues. As root-end filling materials come into contact with periradicular tissues, knowledge of the tissue response is crucial. Almost every available dental restorative material has been suggested as the root-end material of choice at a certain point in the past. This literature review on root-end filling materials will evaluate and comparatively analyse the biocompatibility and tissue response to these products, with primary focus on newly introduced materials. PMID:24010077

  7. An investigation of the microstructure and mechanical properties of electrochemically coated Ag(4)Sn dental alloy particles condensed in vitro

    NASA Astrophysics Data System (ADS)

    Marquez, Jose Antonio

    As part of the ongoing scientific effort to develop a new amalgam-like material without mercury, a team of metallurgists and electrochemists at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, announced in 1993 the development of a new Ag-Sn dental alloy system without mercury that sought to replace conventional dental amalgams. They used spherical Ag3Sn and Ag4Sn intermetallic dental alloy particles, commonly used in conventional dental alloys, and coated them with electrodeposited silver with newly-developed electrolytic and immersion techniques. The particles had relatively pure silver coatings that were closely adherent to the intermetalfic cores. These silver-coated particles, due to silver's plasticity at room temperature, were condensed into PlexiglasRTM molds with the aid of an acidic surface activating solution (HBF4) and a mechanical condensing device, producing a metal-matrix composite with Ag3,4Sn filler particles surrounded by a cold-welded silver matrix. Since silver strain hardens rather easily, the layers had to be condensed in less than 0.5 mm increments to obtain a dense structure. Mechanical testing at NIST produced compressive strength values equal to or greater than those of conventional dental amalgams. Because of its potential for eliminating mercury as a constituent in dental amalgam, this material created a stir in dental circles when first developed and conceivably could prove to be a major breakthrough in the field of dental restoratives. To date, the chief impediments to its approval for human clinical applications by the Food and Drug Administration are the potentially-toxic surface activating solution used for oxide reduction, and the high condensation pressures needed for cold welding because of the tendency for silver to strain harden. In this related study, the author, who has practiced general dentistry for 25 years, evaluates some of the mechanical and microstructural properties of these

  8. Amalgam contact hypersensitivity lesion: an unusual presentation-report of a rare case.

    PubMed

    Ramnarayan, Bk; Maligi, Pm; Smitha, T; Patil, Us

    2014-09-01

    Amalgam or its components may cause Type IV hypersensitivity reactions on the oral mucosa. These amalgam contact hypersensitivity lesions (ACHL) present as white striae and plaques, erythematous, erosive, atrophic, or ulcerative lesions. Postinflammatory pigmentation in such lesions and pigmentation due to amalgam incorporation in the soft tissue have been reported in the literature. However, ACHL presenting primarily as a black pigmented lesion is extremely rare if not reported. The clinician should be aware of one such presentation of ACHL; we report a unique case of ACHL in a 30-year-old female with such a pigmented lesion in close contact with amalgam restorations. The lesion regressed considerably in a year after replacement of the restoration with posterior composites.

  9. DETERMINATION OF TOTAL MERCURY IN FISH TISSUES USING PYROLYSIS ATOMIC ABSORPTION SPECTROMETRY WITH GOLD AMALGAMATION

    EPA Science Inventory

    A simple and rapid procedure for measuring total mercury in fish tissues is evaluated and
    compared with conventional techniques. Using an automated instrument incorporating combustion, preconcentration by amalgamation with gold, and atomic absorption spectrometry (AAS), mill...

  10. Field evaluation of mercury vapor analytical methods: comparison of the "double amalgam method" and ISO 17733.

    PubMed

    Takaya, Mitsutoshi; Joeng, Jee Yeon; Ishihara, Nobuo; Serita, Fumio; Kohyama, Norihiko

    2006-04-01

    In this study, a gold amalgam method called the "Double amalgam method" was compared with the ISO 17733 method for mercury vapor analysis method. In terms of sensitivity and ease of operation, the amalgamation method is superior to the oxidation method. Two parallel samplings were carried out in this research at a button battery factory, where the mercury vapor level in the air was about 0.001 mg/m3 and at a fluorescent lamp factory, where the mercury vapor level was about 0.015 mg/m3. In the both cases, the measured values of the two showed good agreement with each other. As these two workplaces represent typical mercury levels in industries today, the double amalgam method is applicable to working environment measurement.

  11. Amalgam Contact Hypersensitivity Lesion: An Unusual Presentation-Report Of A Rare Case

    PubMed Central

    Ramnarayan, BK; Maligi, PM; Smitha, T; Patil, US

    2014-01-01

    Amalgam or its components may cause Type IV hypersensitivity reactions on the oral mucosa. These amalgam contact hypersensitivity lesions (ACHL) present as white striae and plaques, erythematous, erosive, atrophic, or ulcerative lesions. Postinflammatory pigmentation in such lesions and pigmentation due to amalgam incorporation in the soft tissue have been reported in the literature. However, ACHL presenting primarily as a black pigmented lesion is extremely rare if not reported. The clinician should be aware of one such presentation of ACHL; we report a unique case of ACHL in a 30-year-old female with such a pigmented lesion in close contact with amalgam restorations. The lesion regressed considerably in a year after replacement of the restoration with posterior composites. PMID:25364611

  12. Shear bond strength of brackets bonded to amalgam with different intermediate resins and adhesives.

    PubMed

    Germec, Derya; Cakan, Umut; Ozdemir, Fulya Isik; Arun, Tulin; Cakan, Murat

    2009-04-01

    The aims of this study were to compare, in vitro, the shear bond strength (SBS) of stainless steel orthodontic brackets bonded to silver amalgam with the use of three different intermediate resins and two different adhesives, and to evaluate bond failure mode. Forty-five amalgam specimens were divided into three equal groups. In groups 1 and 2, the brackets were bonded with Unite (3M Unitek) using Reliance Metal Primer (RMP; Reliance Orthodontic Products) and Power Bond OLC (PB OLC; Ortho Organizers Inc.) as intermediate resins, respectively. In group 3, Resinomer and One-Step Plus (OS+; Bisco Inc.) were used. Thirty bovine teeth served as the controls to test bracket bonding to acid-etched enamel with Unite and Resinomer-OS+. After thermocycling from 10 to 50 degrees C 1000 times, all samples were tested for SBS. Bond failure sites were classified using a modified adhesive remnant index (ARI) system. Data were analyzed with one-way analysis of variance, post hoc Tukey multiple comparison and chi-square tests. The results showed that the mean SBS to amalgam surfaces were significantly lower than those to etched bovine enamel (P<0.001). There were no statistically significant differences in mean SBS between the amalgam bonding groups (P>0.05). For the ARI, significant differences were found between the amalgam- and enamel-bonding groups (P<0.001). The mean SBS of stainless steel orthodontic brackets bonded to amalgam surfaces with RMP, PB OLC, OS+ intermediate resins and Unite and Resinomer adhesives was significantly lower than to etched bovine enamel. Bond failure occurred at the amalgam-adhesive interface regardless of the adhesive system and without damage to the amalgam restoration.

  13. Marginal behaviour of self-etch adhesive/composite and combined amalgam-composite restorations.

    PubMed

    Kournetas, Nikos; Kakaboura, Afrodite; Giftopoulos, Dimitrios; Chakmachi, Magdad; Rahiotis, Christos; Geis-Gerstorfer, J

    2010-06-01

    The aim of this study was to compare the marginal and internal adaptation in self-etching adhesive (SEA)/composite restorations with combined amalgam-resin-based composite restorations in the proximal box with and without bonding agent beneath amalgam both before and after load-cycling. Class II restorations, were manufactured as following a) Bonding agent (Clearfil Liner Bond 2V, Kuraray) beneath amalgam (Tytin, SDS Kerr) and resin-based composite (Clearfil APX, Kuraray) with SEA, b) Amalgam without bonding agent and resin-based composite with SEA and c) Resin-based composite with SEA. Each group divided into two equal subgroups (n=8). Marginal and internal adaptation of first subgroup evaluated after 7-day water storage and of the second after load-cycling in chewing simulator for 1.2 x 10(6) cycles. Marginal and internal adaptation at cervical and amalgam-composite sites evaluated by videomicroscope and ranked as "excellent"/"non-excellent". Slices of restorations examined under optical microscope to determine the quality of bonding layer. Defects in cervical adaptation observed in the three restorative techniques examined prior loading. Amalgam-composite combination in proximal surface provided comparable marginal and internal adaptation results at cervical wall, to self-etching-composite combination. Portion (25-37.5%) of amalgam-resin-based composite interfaces in proximal box presented no perfect sealing. The application of bonding agent beneath amalgam resulted in relatively inferior cervical adaptation. Loading resulted in fewer excellent restorations in all three restorative techniques but not in a statistically significant level.

  14. Characterisation of baroque tin amalgam mirrors of the historical Green Vault in Dresden

    NASA Astrophysics Data System (ADS)

    Zywitzki, O.; Nedon, W.; Kopte, T.; Modes, T.

    2008-07-01

    The historical Green Vault, one of Europe’s most sumptuous treasure chambers, has reopened in September 2006 in the Dresden Royal Palace. For the baroque presentation of the artworks the special properties of tin amalgam mirrors are of great importance. A comprehensive analytic characterisation was necessary for restoration and reconstruction. The different original casting glasses were analysed in respect of chemical composition, roughness, waviness and optical properties like chromaticity coordinates and transmittance. The microstructure of the tin amalgam layers were investigated on metallographic cross-sections and by X-ray diffraction. The investigations reveal that the tin amalgam layers are composed of γ-HgSn6-10 phase with a grain size between 5 and 50 μm surrounded by a thin mercury phase with about 2 wt. % tin. However the most important property of the baroque tin amalgam mirrors is a relative low reflectivity of about 59% which is drastically lower than for silver mirrors with a reflectivity of about 96%. According to the characterisation results a suitable glass for reconstruction was selected. The mirror layers were produced by historical tin amalgam technology for the rooms not destroyed by bombarding of Dresden in February 1945. For the completely destroyed Jewel Room pure tin layers were deposited by magnetron sputtering. The results show that this new technology enables an adequate substitute for the original tin amalgam layers.

  15. Dental Training Films.

    ERIC Educational Resources Information Center

    Veterans Administration Medical Center, Washington, DC.

    This dental training films catalog is organized into two sections. Section I is a category listing of the films by number and title, indexed according to generalized headings; categories are as follow: anatomy, articulator systems, complete dentures, dental assisting, dental laboratory technology, dental materials, dental office emergencies,…

  16. Finding Dental Care

    MedlinePlus

    ... Finding Dental Care Where can I find low-cost dental care? Dental schools often have clinics that allow dental ... can I find more information? See Finding Low Cost Dental Care . ​​​​ WWNRightboxRadEditor2 Contact Us 1-866-232-4528 nidcrinfo@ ...

  17. Risk factors and prevalence of dental fluorosis and dental caries in school children of North India.

    PubMed

    Plaka, Kavita; Ravindra, Khaiwal; Mor, Suman; Gauba, Krishan

    2017-01-01

    The aim of the study was to assess the prevalence of dental fluorosis, dental caries, and associated risk factors in the school children of district Fatehgarh Sahib, Punjab, India, using a cross-sectional study design. Oral health status of children aged between 8 and 15 years was assessed using World Health Organization (WHO) 2013 criteria. Dental fluorosis was assessed using Dean's index, and dental caries were recorded using decayed, missing, filled/decayed, extracted, filled (DMF/def) indices. Four hundred school children were examined, of which 207 were in the 8-11-year-old group and 193 were in the 12-15-year-old group. The overall prevalence of dental fluorosis was 4.1%, which might be linked to a high concentration of fluoride in drinking water at certain locations of rural Punjab. The prevalence of dental caries was 36.5% with a mean DMF score of 0.3 and def score of 0.6. Risk factors for dental caries include oral hygiene behavior and sugar consumption patterns. The study highlights the need to increase awareness about the oral health and hygiene among the school children in India.

  18. Synchrotron-radiation-based X-ray micro-computed tomography reveals dental bur debris under dental composite restorations.

    PubMed

    Hedayat, Assem; Nagy, Nicole; Packota, Garnet; Monteith, Judy; Allen, Darcy; Wysokinski, Tomasz; Zhu, Ning

    2016-05-01

    Dental burs are used extensively in dentistry to mechanically prepare tooth structures for restorations (fillings), yet little has been reported on the bur debris left behind in the teeth, and whether it poses potential health risks to patients. Here it is aimed to image dental bur debris under dental fillings, and allude to the potential health hazards that can be caused by this debris when left in direct contact with the biological surroundings, specifically when the debris is made of a non-biocompatible material. Non-destructive micro-computed tomography using the BioMedical Imaging & Therapy facility 05ID-2 beamline at the Canadian Light Source was pursued at 50 keV and at a pixel size of 4 µm to image dental bur fragments under a composite resin dental filling. The bur's cutting edges that produced the fragment were also chemically analyzed. The technique revealed dental bur fragments of different sizes in different locations on the floor of the prepared surface of the teeth and under the filling, which places them in direct contact with the dentinal tubules and the dentinal fluid circulating within them. Dispersive X-ray spectroscopy elemental analysis of the dental bur edges revealed that the fragments are made of tungsten carbide-cobalt, which is bio-incompatible.

  19. Dental education and dental practice.

    PubMed Central

    Moore, J R

    1984-01-01

    This paper relates recent modes of dental practice to changes that the public and government are likely to ask the health care professions to make in the future. As usual they are asking for the best of all worlds. First, that we maintain the clinical model to the highest standards of personal dental care based and tested against the best research at our disposal, whilst we ensure there is no reduction in the high technical standards for which british dentists have a reputation. Second, that the profession is required to consider ways of providing care on the medicosocial model for the whole community at an economic level the country will afford. The broad changes in dental education have been reviewed, from the technical apprenticeship to the establishment of strong university departments in teaching hospitals. The importance of a sound biomedical foundation and of research both to education and the credibility of dental practice as a primary health care profession is stressed if the profession is to retain its position as a sister to medicine and not slide down to that of a technical ancillary. PMID:6374141

  20. Dental Implant Surgery

    MedlinePlus

    Dental implant surgery Overview By Mayo Clinic Staff Dental implant surgery is a procedure that replaces tooth roots with ... look and function much like real ones. Dental implant surgery can offer a welcome alternative to dentures ...

  1. Dental Holography

    NASA Astrophysics Data System (ADS)

    Dirtoft, Ingegerd

    1983-12-01

    Ten years have passed since the first articles appeared in this new field. The qualities of the laser light together with the need of contactless 3-D measurements for different dental purposes seemed to be extremely promising, but still just a few scientists have used the method and mostly for laboratory studies. For some reason there has been a preponderance for orthodontic measurements. This seems to be a bit peculiar from holographic view compared with measurements for engineering purposes, which usually are made on metals. So naturally holography can become a clinical tool for measurements in the field of fixed bridges, removable partial dentures and implants. One of the problems is that the need for holography in dental research must be fulfilled in collaboration with physicists. Only a two-way communication during an entire experiment can balance both technical and odontological demands and thus give practical and clinical important results. The need for an easy way of handling the evaluation to get all required information is another problem and of course the holographic equipment must be converted to a box easy to handle for everyone. At last the position of dental holography today is going to be carefully examined together with an attempt to look into the hopefully exciting and not to utopic future for this research field.

  2. Filling a Conical Cavity

    NASA Astrophysics Data System (ADS)

    Nye, Kyle; Eslam-Panah, Azar

    2016-11-01

    Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.

  3. Evaluation of dental waste management in two cities in Palestine.

    PubMed

    Darwish, R O; Al-Khatib, I A

    2006-01-01

    Disposal of dental waste was investigated at 37 randomly selected clinics in Ramallah and AI-Bireh cities: 31 private practices and 6 public/NGO clinics. Dentists were interviewed regarding their disposal of different forms of dental waste. Disinfectants and X-ray processing solution were thrown down the drain. For sharps, 13.5% of dentists used puncture-resistant containers (only in the public/ NGO clinics), 45.9% discarded needles directly in the garbage after being recapped and 40.5% placed the used needles and blades in closed plastic bottles before throwing in the general garbage. Blood-soaked dressings and amalgam waste were also thrown in the garbage. While 10.75% of dentists were vaccinated against hepatitis B, 47% of the staff at private clinics were not.

  4. [Dental survey of Down syndrome patients. Reflections and synthesis].

    PubMed

    Bianchi, A M; Cuevas, A; Jaramillo, R J

    1991-01-01

    This article presents a work made in year 1990 in the Asociación Odontológica Argentina, in a population of 192 persons with Down's Syndrome. The results were controlled with other Group (Control Group), taken as reference, same number of people, sex and age, not Down's Syndrome diagnostic. Age between 3 and 26 years-old. The examination evaluates: dental caries occurrence, filling and lost teeth, oral hygiene, diet and type of dental treatment received. The report illustrates the differences between the dental health care and dental treatment, in the population with Down's Syndrome and the control Group. The author calls the attention to dental profession to colaborate in the dental health care of Down's Syndrome population.

  5. [Hygiene education in the Laureate Course of Dentistry and Dental Prosthetics: evaluation of student knowledge about the risk of infection in a dental practice environment].

    PubMed

    Minelli, L; Vescarelli, I; Pasquarella, C; Montagna, M T; Castiglia, P; Liguori, G; Annino, I; Bergomi, M; Fabiani, L; Gregorio, P; Majori, S; Petti, S; Stampi, S; Tarsitani, G; Monarca, S

    2003-01-01

    Hygiene education for dental students is crucial in order to control and reduce the risk of infections in their future professional practices. The aim of this study was to evaluate the improvement in university students' knowledge of infectious disease prevention, dental instruments and environmental decontamination following the Course in Dental Hygiene and Prevention. 595 questionnaires were submitted to dental students at twelve Italian Universities; 335 were filled out before the Course began and 260 at the end of the same course. The students in both the PRE-course and at the POST-course evaluations demonstrated adequate knowledge regarding the transmission of infections in dental practices, knowledge improved following the Hygiene course.

  6. Embryotoxicity assays for leached components from dental restorative materials

    PubMed Central

    2011-01-01

    Background Currently, there are no suitable assays available to evaluate the embryotoxicity of leached components from restorative dental materials. Methods The effect of the medium conditioned by composites and amalgam on mouse blastocysts in vitro was tested. The materials were also subcutaneously implanted, and the effect of the medium supplemented with serum from the host blood was evaluated in the embryotoxicity assay. The embryo implantation rate in the material-transplanted mothers was also evaluated. Results The results show that while the culture in media conditioned by amalgams did not affect blastocyst development, the medium conditioned by composites caused blastocyst degeneration and apoptosis. The development of blastocysts in a medium containing serum obtained from animals after transplantation was, however, without effect. Finally, inconsistent reduction in the implantation rate in transplanted mothers was observed. Conclusions In this study, we provide examples of in vitro and in vivo tests that may be used to evaluate embryotoxicity for dental materials. Our results show that leached components from our composite-material induced embryotoxicity in vitro, however, no toxicity was observed when subcutaneously implanted in vivo. This highlights the necessity of integrated in vitro and in vivo tests for valuable predictive estimation of embryotoxicity for complex materials. PMID:21978455

  7. Joint amalgamation of most parsimonious reconciled gene trees

    PubMed Central

    Scornavacca, Celine; Jacox, Edwin; Szöllősi, Gergely J.

    2015-01-01

    Motivation: Traditionally, gene phylogenies have been reconstructed solely on the basis of molecular sequences; this, however, often does not provide enough information to distinguish between statistically equivalent relationships. To address this problem, several recent methods have incorporated information on the species phylogeny in gene tree reconstruction, leading to dramatic improvements in accuracy. Although probabilistic methods are able to estimate all model parameters but are computationally expensive, parsimony methods—generally computationally more efficient—require a prior estimate of parameters and of the statistical support. Results: Here, we present the Tree Estimation using Reconciliation (TERA) algorithm, a parsimony based, species tree aware method for gene tree reconstruction based on a scoring scheme combining duplication, transfer and loss costs with an estimate of the sequence likelihood. TERA explores all reconciled gene trees that can be amalgamated from a sample of gene trees. Using a large scale simulated dataset, we demonstrate that TERA achieves the same accuracy as the corresponding probabilistic method while being faster, and outperforms other parsimony-based methods in both accuracy and speed. Running TERA on a set of 1099 homologous gene families from complete cyanobacterial genomes, we find that incorporating knowledge of the species tree results in a two thirds reduction in the number of apparent transfer events. Availability and implementation: The algorithm is implemented in our program TERA, which is freely available from http://mbb.univ-montp2.fr/MBB/download_sources/16__TERA. Contact: celine.scornavacca@univ-montp2.fr, ssolo@angel.elte.hu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:25380957

  8. Evaluation of efficacy of restorative dental treatment provided under general anesthesia at hospitalized pediatric dental patients of Isfahan

    PubMed Central

    Eshghi, Alireza; Samani, Mahdi Jafarzadeh; Najafi, Naghme Feyzi; Hajiahmadi, Maryam

    2012-01-01

    Background: General anesthesia (GA) allows dental treatment to be rendered under optimal conditions, theoretically ensuring ideal outcomes. The aim of this study was to determine the efficacy of restorative dental procedures performed under GA. Materials and Methods: In this cross-sectional retrospective study, 305 pediatric patients who had been treated under GA 6 to 24 months before our survey at Isfahan's hospitalized dentistry center were examined. The examination was performed on dental chair with oral mirror and dental probe. The results were recorded in a special form for each patient for statistical analysis and evaluation of restorations to be successful or failed. Statistical analysis was performed by chi-square and fisher exact tests for comparison between success rates of restorations and Kendall's tau-b test for evaluating the effect of time on success rates of them (P < 0.05). Results: Stainless steel crown restorations had significantly better results vs class I and class II amalgam and class I and class II tooth color restorations. All types of posterior tooth color restorations had statistically same results with amalgam restorations. Anterior composite resin build-up represented significantly low success rates. The failure rates of stainless steel crown and anterior composite resin build-up restorations did not correlate with the time of follow-up (P = 0.344 and P = 0.091, respectively). Conclusion: Stainless steel crown restorations had significantly better results vs other posterior restorations. The failure rates of stainless steel crown and anterior composite resin build-up restorations did not correlate with the time of follow-up in comparison of other restorations. PMID:23162592

  9. Decisions of practitioners regarding placement of amalgam and composite restorations in general practice settings.

    PubMed

    Pink, F E; Minden, N J; Simmonds, S

    1994-01-01

    This study was undertaken to analyze the current reasons practitioners in general practice settings choose to place amalgam and composite restorations. Data were gathered on individual restorations in the clinical setting to provide information on reasons practitioners state that restorations are placed, the type of material most often placed in different restoration classifications, and the age of restorations at the time of replacement. The results of this study indicate that approximately one-half of all restorations, both amalgam and composite, were placed to treat primary caries. One-half of the remaining restorations placed, i.e., not including those with primary caries, were placed to treat recurrent caries. With respect to restorative materials, amalgam was most often placed in class 1 and class 2 situations (88.9% of the amalgam restorations reported), while composite was most often placed in class 3, 4, or 5 situations (77.4% of the composite restorations reported). From the total data set returned for replaced restorations, only 20% of the data forms reported on verified longevity of the restoration being replaced. Analysis of these data gave a calculated median longevity for amalgam and composite restorations of 10 years and 5 years respectively.

  10. Secondary caries formation in vitro around glass ionomer-lined amalgam and composite restorations.

    PubMed

    Dionysopoulos, P; Kotsanos, N; Papadogianis, Y

    1996-08-01

    The aim of this in vitro secondary caries study was to examine the glass-ionomer liner's effect on wall-lesion inhibition when a conventional and a light-cured glass ionomer liner was placed under amalgam and composite resin restorations. Class V preparations in extracted upper premolars were used and ten restorations were used for each of the following groups: (i) two layers of copal varnish and amalgam; (ii) conventional glass-ionomer and amalgam; (iii) light-cured glass-ionomer and amalgam; (iv) bonding agent and light-cured composite resin; (v) conventional glass-ionomer, bonding agent and light-cured composite resin; (vi) light-cured glass-ionomer, extended 0.3 mm short of the enamel margin bonding agent and light-cured composite resin; and (vii) light-cured glass-ionomer, extended 1 mm short of the enamel margin, bonding agent and light-cured composite resin. The teeth were thermocycled and artificial caries were created using an acid-gel. The results of this study showed that artificial recurrent caries can be reduced significantly (P < 0.05) with a glass-ionomer liner under amalgam restorations. The results also showed that when the light-cured glass-ionomer liner was placed 0.3 mm from the cavosurface margin under composite resin restoration, the artificial recurrent caries reduced significantly (P < 0.05).

  11. Dental Pulp Reaction to Cavit Temporary Filling Material.

    DTIC Science & Technology

    1976-09-22

    histologically evaluated at three time periods to identify initial, early and final response. There were no statistically significant differences in pulpal response between Cavit and the zinc oxide- eugenol controls. (Author)

  12. Allergy and corrosion of dental materials in patients with oral lichen planus.

    PubMed

    Lundström, I M

    1984-02-01

    Patients with histologically verified oral lichen planus (OLP) were studied regarding allergic reactions to substances in dental materials, presence of clinical corrosion orally and factors influencing corrosion, such as mixed gold and amalgam therapy, non-precious pin-constructions or complete dentures. The material consisted of 48 OLP patients (33 female, 15 male) and the results were compared with those of a control group (40 patients) and/or general population samples. When patch tested, 39% of the OLP patients reacted to one or more components in dental materials. Reaction to mercury was most common, being noted in 26%. Clinical signs of corrosion were significantly more frequent in the OLP group (72%) than in the control cases (28%). Patients with atrophic-erosive OLP exhibited a significantly higher frequency of corrosion (83%) than those with reticular type (46%). Mixed gold and amalgam therapy and screwposts were equally present in both the OLP and control group and the frequency of complete dentures corresponded to that reported for general populations. A change of dental materials in 8 patients with positive patch tests led to marked oral improvement in 6 cases, 2 of which became completely cured. The frequencies recorded for allergic reactions and corrosion as well as the result of treatment indicate that substances in dental materials may be of significance in cases of OLP.

  13. Cross-Sectional Analysis of National Dental Residency Match Data.

    PubMed

    Prakasam, Sivaraman; Brady, Patrick; Allareddy, Veeratrishul; Rampa, Sankeerth; Shin, Kyungsup; Nalliah, Romesh; Allareddy, Veerasathpurush

    2017-03-01

    The Dental Residency Match (DRM) program provides an ethical and unbiased selection process for applicants to postdoctoral dental programs, based on mutual interests of applicants and programs. The aims of this study were to conduct a descriptive analysis of DRM metrics for the years 2008 to 2015 and to test the hypothesis that there was a difference in number of ranks submitted between programs that filled all their offered positions and those that did not. DRM metrics data from years 2008 to 2015 were obtained from the National Matching Service. Trend analyses and panel data assessments were made. Six types of postdoctoral dental programs (GPR, AEGD, oral and maxillofacial surgery, pediatric dentistry, orthodontics, and dental anesthesiology) participate in the DRM program. The results showed that the number of programs participating and number of residency positions offered increased over the study period. The programs that filled all their positions ranked more applicants than the programs that did not fill their positions (p<0.05). The number of acceptable applicants increased over the study period for all programs except those in dental anesthesiology. These results suggest that participation in DRM is increasing, most programs are able to fill their positions with acceptable applicants, and programs seeking to fill all their positions need to submit a large number of ranks.

  14. Loose-fill insulations

    SciTech Connect

    1995-05-01

    Whether you are increasing the insulation levels in your current home or selecting insulation for a new home, choosing the right insulation material can be challenging. Fibrous loose-fill insulations such as cellulose, fiberglass, and rock wool are options you may wish to consider. This publication will introduce you to these materials--what they are, how they are applied, how they compare with each other, and other considerations regarding their use--so that you can decide whether loose fills are right for your home.

  15. Child Indicators: Dental Health.

    ERIC Educational Resources Information Center

    Lewit, Eugene M.; Kerrebrock, Nancy

    1998-01-01

    Reviews measures of dental health in children and the evidence on child dental health. Although children's dental health has improved over the past two decades, many poor children do not receive necessary dental health services, and reasons for this failure are summarized. (SLD)

  16. Weaker dental enamel explains dental decay.

    PubMed

    Vieira, Alexandre R; Gibson, Carolyn W; Deeley, Kathleen; Xue, Hui; Li, Yong

    2015-01-01

    Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is "weaker" while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution.

  17. Replacing Amalgam Restorations: A Standardized Protocol Based on Analyzing Tissue Physicochemical Modifications.

    PubMed

    Decup, Franck; Epaillard, Alexandre; Chemla, Florence

    2015-12-01

    Almost 60% of operative dentistry is devoted to replacing restorations. When practitioners have to replace an amalgam restoration, they tend to opt for an adhesive restoration, as it is conservative of tooth tissues and mimics the natural appearance of teeth. Based on a literature review, the aim of this article is to determine the best tissue approach when replacing an old amalgam by a new adhesive restoration. After analyzing and understanding tissue alterations due to the amalgam corrosion process, the authors propose an analytical approach to managing the situation. Both tissue orientated and specific mechanical approaches are developed and should be implemented to carry out the optimal clinical procedure and achieve the most conservative and durable treatment.

  18. Taguchi optimization: Case study of gold recovery from amalgamation tailing by using froth flotation method

    NASA Astrophysics Data System (ADS)

    Sudibyo, Aji, B. B.; Sumardi, S.; Mufakir, F. R.; Junaidi, A.; Nurjaman, F.; Karna, Aziza, Aulia

    2017-01-01

    Gold amalgamation process was widely used to treat gold ore. This process produces the tailing or amalgamation solid waste, which still contains gold at 8-9 ppm. Froth flotation is one of the promising methods to beneficiate gold from this tailing. However, this process requires optimal conditions which depends on the type of raw material. In this study, Taguchi method was used to optimize the optimum conditions of the froth flotation process. The Taguchi optimization shows that the gold recovery was strongly influenced by the particle size which is the best particle size at 150 mesh followed by the Potassium amyl xanthate concentration, pH and pine oil concentration at 1133.98, 4535.92 and 68.04 gr/ton amalgamation tailing, respectively.

  19. [Phase transition analysis of ancient bronze mirror surface tin amalgam in heating].

    PubMed

    Zhang, Shao-yun; Qin, Ying

    2010-10-01

    Taking advantage of theta-theta scanning (vertical goniometer) sealed and ceramic X-ray tube full-automatic diffractometer, which can be heated and detected at the same time when the temperature is between normal temperature and 1200 degrees C, and X-ray fluorescence, and combining surface feature with character, high tin bronze mirror which had been daubed "tin amalgam" was detected and analyzed. It can prove that phase with Hg will disappear gradually when the sample is heated to the temperature higher than the boiling point of Hg; It indicates that bronze surface cannot be as a proof of "tin amalgam" used whether it contains Hg, moreover, it is not necessary that bronze mirror is covered with "tin amalgam" in terms of application.

  20. Dental education in Colombia

    PubMed Central

    Jaramillo, Jorge A.; Pulido, Jairo H. Ternera; Núñez, Jaime A. Castro; Bird, William F.; Komabayashi, Takashi

    2014-01-01

    This article describes Colombia's development of formal dentistry, its dental school system, curriculum, and dental licensure, and current issues in oral health care. In 1969, there were only 4 dental schools in Colombia; at this writing there are 21. Five dental schools are public and the other 16 are private. Nearly all classes are conducted in Spanish. Undergraduate pre-dental coursework is not a prerequisite for dental school in Colombia. To obtain licensure, Colombian dental students must complete 5 years of study in dental school, earn a diploma, and work for the government for 1 year. There are approximately 41,400 dentists in Colombia, and the number is increasing quickly. However, the unemployment rate among dentists is very high, even though graduation from dental school is extremely difficult. Although the 1,100:1 ratio of citizens to dentists is considered satisfactory, access to dental care is limited due to the high rate of poverty. PMID:20339245

  1. Effect of Self-etch Adhesives on Self-sealing Ability of High-Copper Amalgams

    PubMed Central

    Moazzami, Saied Mostafa; Moosavi, Horieh; Moddaber, Maryam; Parvizi, Reza; Moayed, Mohamad Hadi; Mokhber, Nima; Meharry, Michael; B Kazemi, Reza

    2016-01-01

    Statement of the Problem: Similar to conventional amalgam, high-copper amalgam alloy may also undergo corrosion, but it takes longer time for the resulting products to reduce microleakage by sealing the micro-gap at the tooth/amalgam interface. Purpose: The aim of this study was to evaluate the effect of self-etch adhesives with different pH levels on the interfacial corrosion behavior of high-copper amalgam restoration and its induction potential for self-sealing ability of the micro-gap in the early hours after setting by means of Electro-Chemical Tests (ECTs). Materials and Method: Thirty cylindrical cavities of 4.5mm x 4.7mm were prepared on intact bicuspids. The samples were divided into five main groups of application of Adhesive Resin (AR)/ liner/ None (No), on the cavity floor. The first main group was left without an AR/ liner (No). In the other main groups, the types of AR/ liner used were I-Bond (IB), Clearfil S3 (S3), Single Bond (SB) and Varnish (V). Each main group (n=6) was divided into two subgroups (n=3) according to the types of the amalgams used, either admixed ANA 2000 (ANA) or spherical Tytin (Tyt). The ECTs, Open Circuit Potential (OCP), and the Linear Polarization Resistance (LPR) for each sample were performed and measured 48 hours after the completion of the samples. Results: The Tyt-No and Tyt-IB samples showed the highest and lowest OCP values respectively. In LPR tests, the Rp values of ANA-V and Tyt-V were the highest (lowest corrosion rate) and contrarily, the ANA-IB and Tyt-IB samples, with the lowest pH levels, represented the lowest Rp values (highest corrosion rates). Conclusion: Some self-etch adhesives may increase interfacial corrosion potential and self-sealing ability of high-copper amalgams. PMID:27942548

  2. Benchmarking parameter-free AMaLGaM on functions with and without noise.

    PubMed

    Bosman, Peter A N; Grahl, Jörn; Thierens, Dirk

    2013-01-01

    We describe a parameter-free estimation-of-distribution algorithm (EDA) called the adapted maximum-likelihood Gaussian model iterated density-estimation evolutionary algorithm (AMaLGaM-ID[Formula: see text]A, or AMaLGaM for short) for numerical optimization. AMaLGaM is benchmarked within the 2009 black box optimization benchmarking (BBOB) framework and compared to a variant with incremental model building (iAMaLGaM). We study the implications of factorizing the covariance matrix in the Gaussian distribution, to use only a few or no covariances. Further, AMaLGaM and iAMaLGaM are also evaluated on the noisy BBOB problems and we assess how well multiple evaluations per solution can average out noise. Experimental evidence suggests that parameter-free AMaLGaM can solve a wide range of problems efficiently with perceived polynomial scalability, including multimodal problems, obtaining the best or near-best results among all algorithms tested in 2009 on functions such as the step-ellipsoid and Katsuuras, but failing to locate the optimum within the time limit on skew Rastrigin-Bueche separable and Lunacek bi-Rastrigin in higher dimensions. AMaLGaM is found to be more robust to noise than iAMaLGaM due to the larger required population size. Using few or no covariances hinders the EDA from dealing with rotations of the search space. Finally, the use of noise averaging is found to be less efficient than the direct application of the EDA unless the noise is uniformly distributed. AMaLGaM was among the best performing algorithms submitted to the BBOB workshop in 2009.

  3. Atypical Forensic Dental Identifications.

    PubMed

    Cardoza, Anthony R; Wood, James D

    2015-06-01

    Forensic dental identification specialists are typically the last conventional option for postmortem identification. Forensic dental identification is most often accomplished by comparing radiographs of the decedent's teeth with the dental radiographs obtained from the dentist of the suspected victim. Unfortunately, antemortem dental radiographs are not always available. When presented with this challenge, the authors of this article have been successful in completing identifications using means other than dental radiographic comparison.

  4. Artifacts resembling budding bacteria produced in placer-gold amalgams by nitric acid leaching

    USGS Publications Warehouse

    Watterson, J.R.

    1994-01-01

    Microscopic filiform morphologies in gold which are indistinguishable from forms originally interpreted as bacterial in origin were produced in the laboratory by treating amalgams made from natural and artificial gold with hot nitric acid. Textures ranging from cobblestone to deeply crenulated to nodular filiform were produced in the laboratory from all tested natural and artificial gold amalgams; analogous textures widespread in Alaskan placer gold may have a similar inorganic origin. These results indicate that morphology alone cannot be considered adequate evidence of microbial involvement in gold formation. -Author

  5. Artifacts resembling budding bacteria produced in placer-gold amalgams by nitric acid leaching

    USGS Publications Warehouse

    Watterson, J.R.

    1994-01-01

    Microscopic filiform morphologies in gold which are indistinguishable from forms originally interpreted as bacterial in origin were produced in the laboratory by treating amalgams made from natural and artificial gold with hot nitric acid. Textures ranging from cobblestone to deeply crenulated to nodular filiform were produced in the laboratory from all tested natural and artificial gold amalgams; analogous textures widespread in Alaskan placer gold may have a similar inorganic origin. These results indicate that morphology alone cannot be considered adequate evidence of microbial involvement in gold formation.

  6. Are there differences in oral health and oral health behavior between individuals with high and low dental fear?

    PubMed

    Schuller, Annemarie A; Willumsen, Tiril; Holst, Dorthe

    2003-04-01

    Epidemiological studies of the relationship between dental fear, use of dental services, and oral health in different age groups in a common population are scarce. Dental fear and its relationships are usually described in individuals with high dental fear only. The purposes of this study were to describe the prevalence of dental fear in the Norwegian adult population according to age, and to explore differences in oral health, oral hygiene, and visiting habits between individuals with high and low dental fear. For the present study, data from the Trøndelag-94 study were used. The prevalence of dental fear in our study population of adults in Trøndelag, Norway was 6.6%. There was a tendency for individuals with high dental fear to engage in avoidance behavior more frequently than the low dental fear group. Individuals with high dental fear had a statistically significantly higher number of decayed surfaces (DS), decayed teeth, (DT) and missing teeth (MT) but a statistically significantly lower number of filled surfaces (FS), filled teeth (FT), functional surfaces (FSS), and functional teeth (FST). There were no differences in DMFS and DMFT between the groups of high and low dental fear. Since one of the superior aims of the dental profession is to help a patient to achieve a high number of functional teeth throughout life, consequently detecting and treating dental fear should therefore be an important aspect of dental processionals' work.

  7. Biological properties of IRM with the addition of hydroxyapatite as a retrograde root filling material.

    PubMed

    Owadally, I D; Chong, B S; Pitt Ford, T R; Wilson, R F

    1994-10-01

    The effect of adding 10% & 20% hydroxyapatite (HAP) on the antibacterial activity and cytotoxicity of IRM (Intermediate Restorative Material) when used as a retrograde root filling was compared with amalgam, a commonly used material. The antibacterial activity was assessed using the agar diffusion inhibitory test. Forty standardized pellets of each material were produced. Fresh materials, and materials aged for 1 week in sterile distilled water, were placed on blood agar plates inoculated with Streptococcus anginosus (milleri) or Enterococcus faecalis. The presence and diameter of zones of inhibition were recorded at intervals of 3, 7 and 10 days. There was no statistically significant overall difference in the response of the two bacteria tested. However, there were statistically significant overall differences in diameters of the zones of inhibition related to different materials, period of exposure and ageing of materials (P < 0.001). The diameter of the zones of inhibition increased with time for all materials, fresh and aged. IRM and both the HAP-modified forms produced large zones of inhibition. Amalgam produced no measureable zones of inhibition whether aged or fresh, regardless of period of exposure and was different from the other materials (P < 0.001). The cytotoxicity was assessed using the Millipore filter method. Ten standardized pellets of each material were produced and aged by storage in sterile distilled water for 72 h. Ten filters were included as controls. Amalgam produced a consistent cytotoxic score of 1, and the difference between amalgam and the other materials was statistically significant (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Toxic effects of various retrograde root filling materials on gingival fibroblasts and rat sarcoma cells.

    PubMed

    Peltola, M; Salo, T; Oikarinen, K

    1992-06-01

    The aim of this in vitro study was to evaluate the effect of amalgam, glass ionomer, composite and titanium on the growth of gingival fibroblasts (GF) and rat sarcoma cells (UMR) in vitro. The cells were either obtained from gingival biopsies taken during deliberation of unerupted canines (GF) or were of commercial origin (UMR). Equal numbers of cells were placed on culture dishes and incubated for a period of two weeks with the freshly prepared test materials. The cultures were photographed through a light microscope after 7 days incubation and finally counted after 14 days. It was shown that the proliferation of gingival fibroblasts was less disturbed by titanium, being approximately 96% of the control value (cell cultures without test particles), followed by composite, amalgam and glass ionomer (61%, 49% and 35% of the control value respectively). The number of UMR cells after 14 days incubation with the various materials was 76% of the control value with titanium, 12% with composite and 5% with both amalgam and glass ionomer. Inhibition of cell growth (UMR) around the test particles was most prominent around amalgam and glass ionomer, followed by composite and titanium. These effects were noted only with freshly prepared components however, so that the toxic reaction was less pronounced or minimal in a second incubation using the same particles sterilized in between. The results demonstrated that potential retrograde root filling materials have a variable toxic effect on gingival fibroblasts and rat sarcoma cells. The fact that the influence on proliferation disappeared when the test was performed with materials already tested once may be of clinical importance when estimating the biocompatibility in vivo.

  9. Parents’ Oral Health Literacy and its Impact on their Children’s Dental Health Status

    PubMed Central

    Khodadadi, Effat; Niknahad, Ayshe; Sistani, Mohammad Mehdi Naghibi; Motallebnejad, Mina

    2016-01-01

    Introduction Because parents play a key role in children’s dental health, the aim of this study was to determine the relationship between parents’ oral health literacy (OHL) and their children’s dental health status in Babol, Iran. Methods In this cross sectional study a total of 384 children aged 21 months to 84 months who attended the dental clinic of Babol University of Medical Sciences between September 2015 and February 2016 were examined. We measured dmft index only for primary dentition; during examination the accompanying parent completed the “Oral Health Literacy-Adults Questionnaire”. Comparing mean analysis, such as one-way analysis of variance (ANOVA), and an independent-samples t-test, served to compare children’s dental caries, missing, and dental fillings’ mean differences, between subgroups. In addition, the relationship between OHL, children’s dental caries, and dental fillings was assessed using multiple linear regression models while controlling for socioeconomic and demographic factors. All data were analyzed by SPSS version 22. Results Children’s mean age was 55.1 months (SD: 13.7), while 47% were girls. Mean children’s dental caries, missing, filling, and mean dmft index were 6.5, 0.4, 1.2, and 8.2 respectively. Parents with inadequate OHL had children with more dental caries (p=0.005), however this relation had no significance while controlling for background factors. Increasing children’s dental fillings was significantly related with families living in urban regions (p=0.01, 95% CI: 0.11 to 1.12), and parents with adequate OHL (p=0.02, 95% CI: 0.08 to 1.05). Conclusion Inadequate parents’ OHL was associated with children having high dental caries and less dental fillings. Therefore, providing interventions to improve parents’ OHL would be valuable in children’s dental health promotion programs, especially in countries with a developing oral health system. PMID:28163858

  10. The Decim system for the production of dental restorations.

    PubMed

    Sjölin, R; Sundh, A; Bergman, M

    1999-07-01

    The general background to the development of CAD/CAM is presented in short. Specific problems when using this technique for the manufacturing of dental restorations are emphasized, and then the reverse engineering and CAD/CAM process that have been implemented in the Decim (Dentronic AB, Skellefteå, Sweden) system are presented. The system is organized in the following way: 1. The measurement process is encapsulated in a product called Decim Reader. 2. The design functionality is provided by software running on a conventional personal computer. This unit is called Decim Designer. 3. The CAM calculation is done by a dedicated personal computer, the Decim Calculator, that does not require any user interaction. 4. The actual manufacturing of the restorations is performed in the Decim Producer that works with a grinding technique. These components communicate via a local computer network or, when a distributed solution is desired, via internet. The Decim System is presently used for the production of dental ceramic restorations, and it is the only system which can be used for manufacturing inlays of yttria-stabilized zirconia. This ceramic material is CE-approved under the brand name Denzir (Dentronic AB, Skellefteå, Sweden). Due to its favorable mechanical properties, it may be an alternative to dental amalgam, and is therefore of topical interest in dentistry. The use of computer-based techniques for manufacturing dental restorations is briefly outlined and commented on.

  11. Diagnosis and treatment of dental emergencies in two Finnish cities.

    PubMed

    Widström, E; Pietilä, I; Nilsson, B

    1990-06-01

    According to the present clinical survey of dental emergencies treated by organised emergency services in two of the larger Finnish cities, the main causes (64 per cent) of the problems leading to these visits were caries and its consequences. In about 80 per cent of the 839 cases treated, the acute treatment was based on clinical examination only. Temporary fillings were provided for 19 per cent, permanent fillings for 8 per cent, endodontic treatment for 22 per cent and extractions for 14 per cent of the patients. Extractions were most often provided for patients who normally visited a dentist irregularly and these had a low mean number of teeth. Patients with pain lasting longer than a week were likely to receive endodontic treatment, whereas permanent fillings were provided for regular dental visitors who had their own dentists. About 90 per cent of the patients were considered to need other dental treatment in addition to the treatment of the acute condition.

  12. Gas filled panel insulation

    DOEpatents

    Griffith, B.T.; Arasteh, D.K.; Selkowitz, S.E.

    1993-12-14

    A structural or flexible highly insulative panel which may be translucent, is formed from multi-layer polymeric material in the form of an envelope surrounding a baffle. The baffle is designed so as to minimize heat transfer across the panel, by using material which forms substantially closed spaces to suppress convection of the low conductivity gas fill. At least a portion of the baffle carries a low emissivity surface for suppression of infrared radiation. 18 figures.

  13. Gas filled panel insulation

    DOEpatents

    Griffith, Brent T.; Arasteh, Dariush K.; Selkowitz, Stephen E.

    1993-01-01

    A structural or flexible highly insulative panel which may be translucent, is formed from multi-layer polymeric material in the form of an envelope surrounding a baffle. The baffle is designed so as to minimize heat transfer across the panel, by using material which forms substantially closed spaces to suppress convection of the low conductivity gas fill. At least a portion of the baffle carries a low emissivity surface for suppression of infrared radiation.

  14. Exposure to volatile methacrylates in dental personnel.

    PubMed

    Hagberg, Stig; Ljungkvist, Göran; Andreasson, Harriet; Karlsson, Stig; Barregård, Lars

    2005-06-01

    Dental personnel are exposed to acrylates due to the acrylic resin-based composites and bonding agents used in fillings. It is well known that these compounds can cause contact allergy in dental personnel. However, in the 1990s, reports emerged on asthma also caused by methacrylates. The main volatile acrylates in dentistry are 2-hydroxyethyl methacrylate and methyl methacrylate. The aim of this study was to quantify the exposure to these acrylates in Swedish dental personnel. We studied the exposure to 2-hydroxyethyl methacrylate and methyl methacrylate in five randomly selected public dental clinics and at the Faculty of Odontology at Göteborg University. In total, 21 whole-day and 46 task-specific short-term (1-18 min) measurements were performed. The median 8-hour time-weighted averages were 2.5 microg/m3 (dentists) and 2.9 microg/m3 (dental nurses) for 2-hydroxyethyl methacrylate, and 0.8 microg/m3 (dentists) and 0.3 microg/m3 (dental nurses) for methyl methacrylate. The maximum short-term exposure levels were 79 microg/m3 for 2-hydroxyethyl methacrylate and 15 microg/m3 for methyl methacrylate, similar in dentists and dental nurses. The observed levels are much lower than in complete denture fabrication. We found only one previous study in dentistry and it showed similar results (though it reported short-term measurements only). Irritant effects would not be expected in healthy people at these levels. Nevertheless, occupational respiratory diseases due to methacrylates may occur in dental personnel, and improvements in the handling of these chemicals in dentistry are warranted. This includes better vials for the bonding agents and avoiding evaporation from discarded materials.

  15. Assessment of exposures and potential risks to the US adult population from wear (attrition and abrasion) of gold and ceramic dental restorations.

    PubMed

    Richardson, G Mark; Clemow, Scott R; Peters, Rachel E; James, Kyle J; Siciliano, Steven D

    2016-01-01

    Little has been published on the chemical exposures and risks of dental restorative materials other than from dental amalgam and composite resins. Here we provide the first exposure and risk assessment for gold (Au) alloy and ceramic restorative materials. Based on the 2001-2004 US National Health and Nutrition Examination Survey (NHANES), we assessed the exposure of US adults to the components of Au alloy and ceramic dental restorations owing to dental material wear. Silver (Ag) is the most problematic component of Au alloy restorations, owing to a combination of toxicity and proportional composition. It was estimated that adults could possess an average of four tooth surfaces restored with Au alloy before exceeding, on average, the reference exposure level (REL) for Ag. Lithium (Li) is the most problematic component of dental ceramics. It was estimated that adults could possess an average of 15 tooth surfaces restored with ceramics before exceeding the REL for Li. Relative risks of chemical exposures from dental materials decrease in the following order: Amalgam>Au alloys>ceramics>composite resins.

  16. GENETIC POLYMORPHISMS AFFECTING SUSCEPTIBILITY TO MERCURY NEUROTOXICITY IN CHILDREN: SUMMARY FINDINGS FROM THE CASA PIA CHILDREN's AMALGAM CLINICAL TRIAL

    PubMed Central

    Woods, James S.; Heyer, Nicholas J.; Russo, Joan E.; Martin, Michael D.; Farin, Federico M.

    2014-01-01

    Mercury (Hg) is neurotoxic, and children may be particularly susceptible to this effect. A current major challenge is identification of children who may be uniquely susceptible to Hg toxicity because of genetic predisposition. We examined the possibility that common genetic variants that are known to affect neurologic functions or Hg handling in adults would modify the adverse neurobehavioral effects of Hg exposure in children. Three hundred thirty subjects who participated as children in the recently completed Casa Pia Clinical Trial of Dental Amalgams in Children were genotyped for 27 variants of 13 genes that are reported to affect neurologic functions and/or Hg disposition in adults. Urinary Hg concentrations, reflecting Hg exposure from any source, served as the Hg exposure index. Regression modeling strategies were employed to evaluate potential associations between allelic status for individual genes or combinations of genes, Hg exposure, and neurobehavioral test outcomes assessed at baseline and for 7 subsequent years during the clinical trial. Among boys, significant modification of Hg effects on neurobehavioral outcomes over a broad range of neurologic domains was observed with variant genotypes for 4 of 13 genes evaluated. Modification of Hg effects on a more limited number of neurobehavioral outcomes was also observed for variants of another 8 genes. Cluster analyses suggested some genes interacting in common processes to affect Hg neurotoxicity. In contrast, significant modification of Hg effects on neurobehavioral functions among girls with the same genotypes was substantially more limited. These observations suggest increased susceptibility to the adverse neurobehavioral effects of Hg among children, particularly boys, with genetic variants that are relatively common to the general human population. These findings advance public health goals to identify factors underlying susceptibility to Hg toxicity and may contribute to strategies for preventing

  17. Colorimetric Signal Amplification Assay for Mercury Ions Based on the Catalysis of Gold Amalgam.

    PubMed

    Chen, Zhengbo; Zhang, Chenmeng; Gao, Qinggang; Wang, Guo; Tan, Lulu; Liao, Qing

    2015-11-03

    Mercury is a major threat to the environment and to human health. It is highly desirable to develop a user-friendly kit for on-site mercury detection. Such a method must be able to detect mercury below the threshold levels (10 nM) for drinking water defined by the U.S. Environmental Protection Agency. Herein, we for the first time reported catalytically active gold amalgam-based reaction between 4-nitrophenol and NaBH4 with colorimetric sensing function. We take advantage of the correlation between the catalytic properties and the surface area of gold amalgam, which is proportional to the amount of the gold nanoparticle (AuNP)-bound Hg(2+). As the concentration of Hg(2+) increases until the saturation of Hg onto the AuNPs, the catalytic performance of the gold amalgam is much stronger due to the formation of gold amalgam and the increase of the nanoparticle surface area, leading to the decrease of the reduction time of 4-nitrophenol for the color change. This sensing system exhibits excellent selectivity and ultrahigh sensitivity up to the 1.45 nM detection limit. The practical use of this system for Hg(2+) determination in tap water samples is also demonstrated successfully.

  18. Real-Time Plasmonic Monitoring of Single Gold Amalgam Nanoalloy Electrochemical Formation and Stripping.

    PubMed

    Wang, Jun-Gang; Fossey, John S; Li, Meng; Xie, Tao; Long, Yi-Tao

    2016-03-01

    Direct electrodeposition of mercury onto gold nanorods on an ITO substrate, without reducing agents, is reported. The growth of single gold amalgam nanoalloy particles and subsequent stripping was monitored in real-time monitoring by plasmonic effects and single-nanoparticle dark-field spectroelectrochemistry techniques. Time-dependent scattering spectral information conferred insight into the growth and stripping mechanism of a single nanoalloy particle. Four critical stages were observed: First, rapid deposition of Hg atoms onto Au nanorods; second, slow diffusion of Hg atoms into Au nanorods; third, prompt stripping of Hg atoms from Au nanorods; fourth, moderate diffusion from the inner core of Au nanorods. Under high Hg(2+) concentrations, homogeneous spherical gold amalgam nanoalloys were obtained. These results demonstrate that the morphology and composition of individual gold amalgam nanoalloys can be precisely regulated electrochemically. Moreover, gold amalgam nanoalloys with intriguing optical properties, such as modulated plasmonic lifetimes and quality factor Q, could be obtained. This may offer opportunities to extend applications in photovoltaic energy conversion and chemical sensing.

  19. Saturated vapor pressure above the amalgam of alkali metals in discharge lamps

    NASA Astrophysics Data System (ADS)

    Gavrish, S. V.

    2011-12-01

    A theoretical and numerical analysis of the evaporation process of two-component compounds in vapors of alkali metals in discharge lamps is presented. Based on the developed mathematical model of calculation of saturated vapor pressure of the metal above the amalgam, dependences of mass fractions of the components in the discharge volume on design parameters and thermophysical characteristics of the lamp are obtained.

  20. Teaching as an Amalgam of Discourses and the Consequent Need for Appropriate Modes of Reflection.

    ERIC Educational Resources Information Center

    Coldron, John; Smith, Robin

    This paper explores the concept of reflection and reflective practice in teacher education. Teaching is a complex achievement that brings together a number of conceptual, practical, and physical resources in an individual's professional practice. Achievement in teaching is an amalgam of at least four different discourses--science, craft, art, and…

  1. Electrolytic method for the production of lithium using a lithium-amalgam electrode

    DOEpatents

    Cooper, John F.; Krikorian, Oscar H.; Homsy, Robert V.

    1979-01-01

    A method for recovering lithium from its molten amalgam by electrolysis of the amalgam in an electrolytic cell containing as a molten electrolyte a fused-salt consisting essentially of a mixture of two or more alkali metal halides, preferably alkali metal halides selected from lithium iodide, lithium chloride, potassium iodide and potassium chloride. A particularly suitable molten electrolyte is a fused-salt consisting essentially of a mixture of at least three components obtained by modifying an eutectic mixture of LiI-KI by the addition of a minor amount of one or more alkali metal halides. The lithium-amalgam fused-salt cell may be used in an electrolytic system for recovering lithium from an aqueous solution of a lithium compound, wherein electrolysis of the aqueous solution in an aqueous cell in the presence of a mercury cathode produces a lithium amalgam. The present method is particularly useful for the regeneration of lithium from the aqueous reaction products of a lithium-water-air battery.

  2. When Old and New Regionalism Collide: Deinstitutionalization of Regions and Resistance Identity in Municipality Amalgamations

    ERIC Educational Resources Information Center

    Zimmerbauer, Kaj; Paasi, Anssi

    2013-01-01

    Regions as well as their identities and borders are social and discursive constructs that are produced and removed in contested, historically contingent and context-bound processes of institutionalization and deinstitutionalization. This article studies the deinstitutionalization of regions in the context of municipality amalgamations and the…

  3. Amalgam Surface Treatment by Different Output Powers of Er:YAG Laser:SEM Evaluation

    PubMed Central

    Hosseini, Mohammad Hashem; Hassanpour, Mehdi; Etemadi, Ardavan; Ranjbar Omrani, Ladan; Darvishpour, Hojat; Chiniforush, Nasim

    2015-01-01

    Introduction: The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM). Methods: Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM. Results: The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularities Conclusion: It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets. PMID:26705463

  4. 75 FR 10331 - In the Matter of: Amalgamated Explorations, Inc., Areawide Cellular, Inc., Genomed, Inc., Global...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-05

    ... [Federal Register Volume 75, Number 43 (Friday, March 5, 2010)] [Notices] [Pages 10331-10332] [FR Doc No: 2010-4801] SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] In the Matter of: Amalgamated Explorations, Inc., Areawide Cellular, Inc., Genomed, Inc., Global Maintech Corp., Military Resale Group, Inc., Verado Holdings, Inc., and...

  5. Dental Auxiliary Occupations. Interim Report.

    ERIC Educational Resources Information Center

    Kingston, Richard D.

    As part of a dental auxiliaries project, a Dental Auxiliary National Technical Advisory Committee was established, and its major undertaking was to assist in the development of a functional inventory for each of the three dental auxiliary occupations (dental assisting, dental hygiene, and dental laboratory technology). The analysis consisted of…

  6. Dye filled security seal

    DOEpatents

    Wilson, Dennis C. W.

    1982-04-27

    A security seal for providing an indication of unauthorized access to a sealed object includes an elongate member to be entwined in the object such that access is denied unless the member is removed. The elongate member has a hollow, pressurizable chamber extending throughout its length that is filled with a permanent dye under greater than atmospheric pressure. Attempts to cut the member and weld it together are revealed when dye flows through a rupture in the chamber wall and stains the outside surface of the member.

  7. Clinical Success Rate of Compomer and Amalgam Class II Restorations in First Primary Molars: A Two-year Study.

    PubMed

    Ghaderi, Faezeh; Mardani, Ali

    2015-01-01

    Background and aims. The majority of failures in Class II amalgam restorations occur in the first primary molar teeth; in addition, use of compomer instead of amalgam for primary molar teeth restorations is a matter of concern. The aim ofthe present study was to compare the success rate of Class II compomer and amalgam restorations in the first primary molars. Materials and methods. A total of 17 amalgams and 17 compomer restorations were placed in 17 children based on a split-mouth design. Restorations were assessed at 12- and 24-month intervals for marginal integrity, the anatomic form and recurrent caries. Data were analyzed with SPSS 11. Chi-squared test was applied for the analysis. Statistical significance was set at P<0.05. Results. A total 34 restorations of 28 restorations (14 pairs) of the total restorations still survived after 24 months. Compomerrestorations showed significantly better results in marginal integrity. Recurrent caries was significantly lower incompomer restorations compared to amalgam restorations. Cumulative success rate at 24-month interval was significantlyhigher in compomer restorations compared to amalgam restorations. There was no statistically significant difference inanatomic form between the two materials. Conclusion. Compomer appears to be a suitable alternative to amalgam for Class II restorations in the first primary mo-lars.

  8. Fluid Dynamics of Bottle Filling

    NASA Astrophysics Data System (ADS)

    McGough, Patrick; Gao, Haijing; Appathurai, Santosh; Basaran, Osman

    2011-11-01

    Filling of bottles is a widely practiced operation in a large number of industries. Well known examples include filling of ``large'' bottles with shampoos and cleaners in the household products and beauty care industries and filling of ``small'' bottles in the pharmaceutical industry. Some bottle filling operations have recently drawn much attention from the fluid mechanics community because of the occurrence of a multitude of complex flow regimes, transitions, and instabilities such as mounding and coiling that occur as a bottle is filled with a fluid. In this talk, we present a primarily computational study of the fluid dynamical challenges that can arise during the rapid filling of bottles. Given the diversity of fluids used in filling applications, we consider four representative classes of fluids that exhibit Newtonian, shear-thinning, viscoelastic, and yield-stress rheologies. The equations governing the dynamics of bottle filling are solved either in their full 3D but axisymmetric form or using the slender-jet approximation.

  9. Dental Exam for Children

    MedlinePlus

    ... and thumb sucking Toddlers, school-age children and adolescents During each regular checkup, the dentist or hygienist ... dental hygienist about proper oral health care for adolescents. American Dental Hygienists' Association. http://www.adha.org/ ...

  10. Hydrogen Filling Station

    SciTech Connect

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    future. Project partners also conducted a workshop on hydrogen safety and permitting. This provided an opportunity for the various permitting agencies and end users to gather to share experiences and knowledge. As a result of this workshop, the permitting process for the hydrogen filling station on the Las Vegas Valley Water District’s land was done more efficiently and those who would be responsible for the operation were better educated on the safety and reliability of hydrogen production and storage. The lessons learned in permitting the filling station and conducting this workshop provided a basis for future hydrogen projects in the region. Continuing efforts to increase the working pressure of electrolysis and efficiency have been pursued. Research was also performed on improving the cost, efficiency and durability of Proton Exchange Membrane (PEM) hydrogen technology. Research elements focused upon PEM membranes, electrodes/catalysts, membrane-electrode assemblies, seals, bipolar plates, utilization of renewable power, reliability issues, scale, and advanced conversion topics. Additionally, direct solar-to-hydrogen conversion research to demonstrate stable and efficient photoelectrochemistry (PEC) hydrogen production systems based on a number of optional concepts was performed. Candidate PEC concepts included technical obstacles such as inefficient photocatalysis, inadequate photocurrent due to non-optimal material band gap energies, rapid electron-hole recombination, reduced hole mobility and diminished operational lifetimes of surface materials exposed to electrolytes. Project Objective 1: Design, build, operate hydrogen filling station Project Objective 2: Perform research and development for utilizing solar technologies on the hydrogen filling station and convert two utility vehicles for use by the station operators Project Objective 3: Increase capacity of hydrogen filling station; add additional vehicle; conduct safety workshop; develop a roadmap for

  11. Accreditation in Dental Hygiene.

    ERIC Educational Resources Information Center

    National Commission on Accrediting, Washington, DC.

    The Council on Dental Education cooperates with the American Dental Hygienists' Association in developing educational requirements for schools of dental hygiene. To be eligible for accreditation, schools must operate on a non-profit basis. A school applying for accreditation completes a previsitation questionnaire concerning its program. The…

  12. Dental Manpower Fact Book.

    ERIC Educational Resources Information Center

    Ake, James N.; Johnson, Donald W.

    Statistical data on many aspects of dental and allied dental personnel supply, distribution, characteristics, and education and on certain other aspects of dental services are presented and discussed. The data on dentist supply show the national trend in the supply of active dentists since 1950 and the concurrent changes in dentist-to-population…

  13. Dental Laboratory Technology.

    ERIC Educational Resources Information Center

    Department of the Air Force, Washington, DC.

    The Air Force dental laboratory technology manual is designed as a basic training text as well as a reference source for dental laboratory technicians, a specialty occupation concerned with the design, fabrication, and repair of dental prostheses. Numerous instructive diagrams and photographs are included throughout the manual. The comprehensive…

  14. DENTAL SCHOOL PLANNING.

    ERIC Educational Resources Information Center

    GALAGAN, DONALD J.

    THIS DISCUSSION PRESENTS A COMPLETE PICTURE OF THE CURRENT STATE OF DENTAL EDUCATION WITH SUGGESTIONS FOR MEETING THE DEMANDS FOR DENTAL STAFF AND FACILITIES. THE AREAS INVESTIGATED ARE (1) OBJECTIVES IN DENTAL EDUCATION--COURSES, TEACHING MODES, INNOVATIONS IN CURRICULUM, COORDINATION OF BASIC AND CLINICAL INSTRUCTION, (2) FACILITY…

  15. Dental Assisting Laboratory Manual.

    ERIC Educational Resources Information Center

    Thiel, Sandra J.

    Compiled to introduce the dental assisting student to various techniques used in the dental office and to present theoretical information essential for the student's professional development, this laboratory guide consists of three units of instruction. The first unit is an introduction to dental assisting and contains five topics of study. The…

  16. Perspectives from Dental Research.

    ERIC Educational Resources Information Center

    Baum, Bruce J.

    1996-01-01

    This paper responds to the Institute of Medicine's 1995 report concerning the present status and future needs of dental education in the United States. It examines whether real reform is occurring at the National Institute of Dental Research, within the academic dental community, and within the practicing profession. It concludes that very little…

  17. Weaker Dental Enamel Explains Dental Decay

    PubMed Central

    Vieira, Alexandre R.; Gibson, Carolyn W.; Deeley, Kathleen; Xue, Hui; Li, Yong

    2015-01-01

    Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is “weaker” while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution. PMID:25885796

  18. Reconstruction-based Digital Dental Occlusion of the Partially Edentulous Dentition

    PubMed Central

    Zhang, Jian; Xia, James J.; Li, Jianfu; Zhou, Xiaobo

    2016-01-01

    Partially edentulous dentition presents a challenging problem for the surgical planning of digital dental occlusion in the field of craniomaxillofacial surgery because of the incorrect maxillomandibular distance caused by missing teeth. We propose an innovative approach called Dental Reconstruction with Symmetrical Teeth (DRST) to achieve accurate dental occlusion for the partially edentulous cases. In this DRST approach, the rigid transformation between two symmetrical teeth existing on the left and right dental model is estimated through probabilistic point registration by matching the two shapes. With the estimated transformation, the partially edentulous space can be virtually filled with the teeth in its symmetrical position. Dental alignment is performed by digital dental occlusion reestablishment algorithm with the reconstructed complete dental model. Satisfactory reconstruction and occlusion results are demonstrated with the synthetic and real partially edentulous models. PMID:26584502

  19. Space-filling percolation

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhijit; Manna, S. S.

    2014-03-01

    A region of two-dimensional space has been filled randomly with a large number of growing circular disks allowing only a "slight" overlapping among them just before their growth stops. More specifically, each disk grows from a nucleation center that is selected at a random location within the uncovered region. The growth rate δ is a continuously tunable parameter of the problem which assumes a specific value while a particular pattern of disks is generated. When a growing disk overlaps for the first time with at least one other disk, its growth is stopped and is said to be frozen. In this paper we study the percolation properties of the set of frozen disks. Using numerical simulations we present evidence for the following: (i) The order parameter appears to jump discontinuously at a certain critical value of the area coverage; (ii) the width of the window of the area coverage needed to observe a macroscopic jump in the order parameter tends to vanish as δ →0; and on the contrary (iii) the cluster size distribution has a power-law-decaying functional form. While the first two results are the signatures of a discontinuous transition, the third result is indicative of a continuous transition. Therefore we refer to this transition as a sharp but continuous transition similar to what has been observed in the recently introduced Achlioptas process of explosive percolation. It is also observed that in the limit of δ →0, the critical area coverage at the transition point tends to unity, implying that the limiting pattern is space filling. In this limit, the fractal dimension of the pore space at the percolation point has been estimated to be 1.42(10) and the contact network of the disk assembly is found to be a scale-free network.

  20. Identification through X-ray fluorescence analysis of dental restorative resin materials: a comprehensive study of noncremated, cremated, and processed-cremated individuals.

    PubMed

    Bush, Mary A; Miller, Raymond G; Prutsman-Pfeiffer, Jennifer; Bush, Peter J

    2007-01-01

    Tooth-colored restorative materials are increasingly being placed in the practice of modern dentistry, replacing traditional materials such as amalgam. Many restorative resins have distinct elemental compositions that allow identification of brand. Not only are resins classifiable by elemental content, but they also survive extreme conditions such as cremation. This is of significance to the forensic odontologist because resin uniqueness adds another level of certainty in victim identification, especially when traditional means are exhausted. In this three-part study, unique combinations of resins were placed in six human cadavers (total 70 restorations). Simulated ante-mortem dental records were created. In a blind experiment, a portable X-ray fluorescence (XRF) unit was used to locate and identify the resin brands placed in the dentition. The technique was successful in location and brand identification of 53 of the restorations, which was sufficient to enable positive victim identification among the study group. This part of the experiment demonstrated the utility of portable XRF in detection and analysis of restorative materials for victim identification in field or morgue settings. Identification of individuals after cremation is a more difficult task, as the dentition is altered by shrinkage and fragmentation, and may not be comparable with a dental chart. Identification of processed cremains is a much greater challenge, as comminution obliterates all structural relationships. Under both circumstances, it is the nonbiological artifacts that aid in identification. Restorative resin fillings can survive these conditions, and can still be named by brand utilizing elemental analysis. In a continuation of the study, the cadavers were cremated in a cremation retort under standard mortuary conditions. XRF was again used to analyze retrieved resins and to identify the individuals based on restorative materials known to exist from dental records. The cremains were

  1. An in vitro comparison of diagnostic accuracy of cone beam computed tomography and phosphor storage plate to detect simulated occlusal secondary caries under amalgam restoration

    PubMed Central

    Shahidi, Shoaleh; Zadeh, Nahal Kazerooni; Sharafeddin, Farahnaz; Shahab, Shahriar; Bahrampour, Ehsan; Hamedani, Shahram

    2015-01-01

    Background: This study was aimed to compare the diagnostic accuracy and feasibility of cone beam computed tomography (CBCT) with phosphor storage plate (PSP) in detection of simulated occlusal secondary caries. Materials and Methods: In this in vitro descriptive-comparative study, a total of 80 slots of class I cavities were prepared on 80 extracted human premolars. Then, 40 teeth were randomly selected out of this sample and artificial carious lesions were created on these teeth by a round diamond bur no. 1/2. All 80 teeth were restored with amalgam fillings and radiographs were taken, both with PSP system and CBCT. All images were evaluated by three calibrated observers. The area under the receiver operating characteristic curve was used to compare the diagnostic accuracy of two systems. SPSS (SPSS Inc., Chicago, IL, USA) was adopted for statistical analysis. The difference between Az value of bitewing and CBCT methods were compared by pairwise comparison method. The inter- and intra-operator agreement was assessed by kappa analysis (P < 0.05). Results: The mean Az value for bitewings and CBCT was 0.903 and 0.994, respectively. Significant differences were found between PSP and CBCT (P = 0.010). The kappa value for inter-observer agreement was 0.68 and 0.76 for PSP and CBCT, respectively. The kappa value for intra-observer agreement was 0.698 (observer 1, P = 0.000), 0.766 (observer 2, P = 0.000) and 0.716 (observer 3, P = 0.000) in PSP method, and 0.816 (observer 1, P = 0.000), 0.653 (observer 2, P = 0.000) and 0.744 (observer 3, P = 0.000) in CBCT method. Conclusion: This in vitro study, with a limited number of samples, showed that the New Tom VGI Flex CBCT system was more accurate than the PSP in detecting the simulated small secondary occlusal caries under amalgam restoration. PMID:25878682

  2. Physical and chemical properties of a new root-end filling material.

    PubMed

    Torabinejad, M; Hong, C U; McDonald, F; Pitt Ford, T R

    1995-07-01

    This study determined the chemical composition, pH, and radiopacity of mineral trioxide aggregate (MTA), and also compared the setting time, compressive strength, and solubility of this material with those of amalgam, Super-EBA, and Intermediate Restorative Material (IRM). X-ray energy dispersive spectrometer in conjunction with the scanning electron microscope were used to determine the composition of MTA, and the pH value of MTA was assessed with a pH meter using a temperature-compensated electrode. The radiopacity of MTA was determined according to the method described by the International Organization for Standardization. The setting time and compressive strength of these materials were determined according to methods recommended by the British Standards Institution. The degree of solubility of the materials was assessed according to modified American Dental Association specifications. The results showed that the main molecules present in MTA are calcium and phosphorous ions. In addition, MTA has a pH of 10.2 initially, which rises to 12.5 three hours after mixing. MTA is more radiopaque than Super-EBA and IRM. Amalgam had the shortest setting time (4 min) and MTA the longest (2 h 45 min). At 24 h MTA had the lowest compressive strength (40 MPa) among the materials, but it increased after 21 days to 67 MPa. Finally, except for IRM, none of the materials tested showed any solubility under the conditions of this study.

  3. Enhancement in resistivity resolution based on the data sets amalgamation technique at Bukit Bunuh, Perak, Malaysia

    NASA Astrophysics Data System (ADS)

    Anderson Bery, Andy; Saad, Rosli; Hidayah, I. N. E.; Azwin, I. N.; Saidin, Mokhtar

    2015-01-01

    In this paper, we have carried out a study with the main objective to enhance the resolution of the electrical resistivity inversion model by introducing the data sets amalgamation technique to be used in the data processing stage. Based on the model resistivity with topography results, the data sets amalgamation technique for pole-dipole and wenner- schlumberger arrays are successful in identifying the boundary or interface of the overburden and weathered granite. Although the electrical resistivity method is well known, the proper selection of an array and appropriate inversion parameters setting such as damping factors are important in order to achieve the study objective and to image the target at the Earth's subsurface characterizations.

  4. Resistance of composite and amalgam core foundations retained with and without pins and bonding agents.

    PubMed

    Imbery, Terence A; Swigert, Ryan; Richman, Brian; Sawicki, Vincent; Pace, Lauren; Moon, Peter C

    2010-01-01

    To compare the resistance of different amalgam and composite core foundations retained by pins, bonding agents, or both, 100 molars were mounted in acrylic resin and their occlusal surfaces were reduced to expose dentin. Pins were inserted at the four line angles of the teeth and matrices were placed. Bonding agents were applied according to the manufacturers' instructions. Amalgam was handcondensed and composite was incrementally added and photocured. Restorations were adjusted to produce specimens (n = 10) 5 mm in height with a 1 mm bevel at the axial-occlusal surface. After immersion in deionized water for 24 hours, specimens were loaded at a 45 degree angle on their beveled surfaces in a Universal Testing Machine at a crosshead speed of 0.02 in./minute. ANOVA and Tukey's tests indicated that FluoroCore 2 (with or without pins) was statistically stronger than all other combinations (p < 0.05).

  5. Lava-Filled Craters

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 12 June 2003

    Craters and hills form high standing streamlined plateaus or islands in a channeled area. The plateaus are rounded in the upstream direction and taper to a point in the downstream direction, indicating that the direction of flow in this area was roughly south to north, or bottom to top. The channels appear to be filled with lava flow deposits that are raised above the channel in some areas. A lava flow diverges around a small streamlined hill near the bottom of the image and then merges again around the northern end of it. Near the top of the image is a crater with a breach on the east (right) side that allowed the lava to flow in, leaving a lobate, high standing deposit. The channels may have been formed by the lava flows that currently fill them or there may have been flow of liquid water that created them before the lava was emplaced.

    Image information: VIS instrument. Latitude 16, Longitude 183 East (177 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built

  6. Improving Medical and Dental Readiness in the Reserve Components

    DTIC Science & Technology

    2012-01-01

    approach for supporting its RC members in meeting IMR requirements, getting vaccinations , and obtain- ing medical and dental treatment as needed. IMR... HPV ), screening for cervical cancer, and testing for chlamydia. Focus on demineralization (“fix and prevent”) rather than cavities (“drill, fill

  7. Dental fellowships in developmental disabilities help broaden care of disabled.

    PubMed

    Ferguson, F S; Kamen, P; Ratner, S; Rosenthal, R L

    1992-11-01

    Continuation of the national trend toward deinstitutionalization and community placement for persons with developmental disabilities, physical handicaps and other medical problems will mean increased demand for dentists trained to care for this segment of the population. The New York State Office of Mental Retardation and Developmental Disabilities now offers dental fellowships in developmental disabilities to help fill the learning gap.

  8. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental handpiece and accessories. 872.4200 Section 872.4200 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... restorations, such as fillings, and for cleaning teeth. (b) Classification. Class I....

  9. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental handpiece and accessories. 872.4200 Section 872.4200 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... restorations, such as fillings, and for cleaning teeth. (b) Classification. Class I....

  10. 21 CFR 872.4200 - Dental handpiece and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental handpiece and accessories. 872.4200 Section 872.4200 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... restorations, such as fillings, and for cleaning teeth. (b) Classification. Class I....

  11. Marketing the dental hygienist as a manager in oral health care settings.

    PubMed

    Thomson, E M

    1989-09-01

    In 1985, the ADHA, in response to the changing health care environment, identified six roles for the future of dental hygiene. The administrator/manager role, one of the six, is an expansion of dental hygiene skills to facilitate the provision of quality oral health care. Oral health care settings require personnel trained in management to accomplish practice-related goals and objectives. Dental hygiene is preparing individuals to assume managerial roles to fill this health care need. This paper discusses the skills and knowledge level required to assume managerial roles and strategies for marketing the dental hygienist as a manager.

  12. Versatile combustion-amalgamation technique for the photometric determination of mercury in fish and environmental samples

    USGS Publications Warehouse

    Willford, Wayne A.; Hesselberg, Robert J.; Bergman, Harold L.

    1973-01-01

    Total mercury in a variety of substances is determined rapidly and precisely by direct sample combustion, collection of released mercury by amalgamation, and photometric measurement of mercury volatilized from the heated amalgam. Up to 0.2 g fish tissue is heated in a stream of O2 (1.2 L/min) for 3.5 min in 1 tube of a 2-tube induction furnace. The released mercury vapor and combustion products are carried by the stream of O2 through a series of traps (6% NaOH scrubber, water condenser, and Mg(CIO4)2 drying tube) and the mercury is collected in a 10 mm diameter column of 24 gauge gold wire (8 g) cut into 3 mm lengths. The resulting amalgam is heated in the second tube of the induction furnace and the volatilized mercury is measured with a mercury vapor meter equipped with a recorder-integrator. Total analysis time is approximately 8 min/sample. The detection limit is less than 0.002 μg and the system is easily converted for use with other biological materials, water, and sediments.

  13. Antibacterial properties of amalgam and composite resin materials used as cores under crowns.

    PubMed

    Al Ghadban, A; Al Shaarani, F

    2012-06-01

    The Aim of this Study was to compare the bacterial growth in the bulk of both amalgam and fluoridated composite resin materials used as cores under crowns at core's surface (in the superficial area of the bulk) and depth levels. With 24 lower premolars, 12 of them were restored with metal posts and amalgam cores (group 1). The rest were restored with glass Fiber-reinforced Composite (FRC) posts and fluoridated composite resin cores (group 2). All specimens were covered with aluminium crowns cemented with resin cement, and then they were soaked in natural saliva for three months. Excoriations abraded from the superficial and the depth areas of the core materials were cultured under aerobic conditions on blood agar plates. After incubation for 2 days, colonies formed on the plates were identified, and the CFU mg(-1) counts were recorded accordingly. Statistical analysis was performed using an independent sample T test. The mean values of CFU mg(-1) counts in group 2 excoriations (surface 39.75, and depth 9.75) were higher than the group 1 excoriations (surface 1.67, and depth 0.42). This study supports the use of amalgam for building up cores due to its antibacterial properties. Composite resin, however, enhanced sizable bacterial growth despite the presence of fluoride.

  14. In vitro corrosion behaviour and microhardness of high-copper amalgams with platinum and indium.

    PubMed

    Ilikli, B G; Aydin, A; Işimer, A; Alpaslan, G

    1999-02-01

    Samples prepared from Luxalloy, GS-80, Permite-C and Logic and polished after 24 h by traditional methods were stored in polypropylene tubes containing phosphate-buffered saline solutions (pH 3.5 and 6.5) and distilled water. The amounts of mercury, silver, tin, copper, zinc, platinum and indium in the test solutions were determined at the first, second, eighth, 52nd and 78th week by atomic absorption spectrometry. At the end of the eighth week the amalgam samples were removed from solutions and evaluated by Rockwell Super Scial Microhardness tester. Statistically significant low amounts of metal ions were measured for Permite-C containing indium and Logic containing platinum. The microhardness test results showed that there were statistically significant increases in the microhardness of Permite-C and Logic. As a result it was shown that the amalgam samples were affected from corrosion conditions to different degrees. Sample of the Logic group that was stored in distilled water, showed smoother surface properties than other amalgam samples containing high copper. However, it was observed that samples of Permite-C group had the smoothest surface properties.

  15. What is dental ecology?

    PubMed

    Cuozzo, Frank P; Sauther, Michelle L

    2012-06-01

    Teeth have long been used as indicators of primate ecology. Early work focused on the links between dental morphology, diet, and behavior, with more recent years emphasizing dental wear, microstructure, development, and biogeochemistry, to understand primate ecology. Our study of Lemur catta at the Beza Mahafaly Special Reserve, Madagascar, has revealed an unusual pattern of severe tooth wear and frequent tooth loss, primarily the result of consuming a fallback food for which these primates are not dentally adapted. Interpreting these data was only possible by combining our areas of expertise (dental anatomy [FC] and primate ecology [MS]). By integrating theoretical, methodological, and applied aspects of both areas of research, we adopted the term "dental ecology"-defined as the broad study of how teeth respond to the environment. Specifically, we view dental ecology as an interpretive framework using teeth as a vehicle for understanding an organism's ecology, which builds upon earlier work, but creates a new synthesis of anatomy and ecology that is only possible with detailed knowledge of living primates. This framework includes (1) identifying patterns of dental pathology and tooth use-wear, within the context of feeding ecology, behavior, habitat variation, and anthropogenic change, (2) assessing ways in which dental development and biogeochemical signals can reflect habitat, environmental change and/or stress, and (3) how dental microstructure and macro-morphology are adapted to, and reflect feeding ecology. Here we define dental ecology, provide a short summary of the development of this perspective, and place our new work into this context.

  16. Dental hygiene in Slovakia.

    PubMed

    Luciak-Donsberger, C; Krizanová, M

    2004-08-01

    This article reports on the development of the dental hygiene profession in Slovakia from a global perspective. The aim is to inform about current developments and to examine, how access to qualified dental hygiene care might be improved and how professional challenges might be met. For an international study on dental hygiene, secondary source data were obtained from members of the House of Delegates of the International Federation of Dental Hygienists (IFDH) or by fax and e-mail from experts involved in the national professional and educational organization of dental hygiene in non-IFDH member countries, such as Slovakia. Responses were followed-up by interviews, e-mail correspondence, visits to international universities, and a review of supporting studies and reference literature. Results show that the introduction of dental hygiene in Slovakia in 1992 was inspired by the delivery of preventive care in Switzerland. Initiating local dentists and dental hygienists strive to attain a high educational level, equitable to that of countries in which dental hygiene has an established tradition of high quality care. Low access to qualified dental hygiene care may be a result of insufficient funding for preventive services, social and cultural lack of awareness of the benefits of preventive care, and of limitations inherent in the legal constraints preventing unsupervised dental hygiene practice. These may be a result of gender politics affecting a female-dominated profession and of a perception that dental hygiene is auxiliary to dental care. International comparison show that of all Eastern European countries, the dental hygiene profession appears most advanced in Slovakia. This is expressed in high evidence-based academic goals, in extensive work with international consultants from the Netherlands and Switzerland, in annual congresses of high professional quality, and in the establishment of a profession, which has not been introduced in all Western EU countries.

  17. Employment of Dental Hygienists as Dental Educators.

    ERIC Educational Resources Information Center

    Fong, Cynthia; Odrich, Johanna

    1987-01-01

    A study of the use of dental hygienists to teach periodontics, preventive dentistry, community dentistry, and public health courses looked at employment patterns and practices and the qualifications of the teachers. (MSE)

  18. Intermittent Surface Water Connectivity: Fill and Spill vs. Fill ...

    EPA Pesticide Factsheets

    Intermittent surface connectivity can influence aquatic systems, since chemical and biotic movements are often associated with water flow. Although often referred to as fill and spill, wetlands also fill and merge. We examined the effects of these connection types on water levels, ion concentrations, and biotic communities of eight prairie pothole wetlands between 1979 and 2015. Fill and spill caused pulsed surface water connections that were limited to periods following spring snow melt. In contrast, two wetlands connected through fill and merge experienced a nearly continuous, 20-year surface water connection and had completely coincident water levels. Fill and spill led to minimal convergence in dissolved ions and macroinvertebrate composition, while these constituents converged under fill and merge. The primary factor determining difference in responses was duration of the surface water connection between wetland pairs. Our findings suggest that investigations into the effects of intermittent surface water connections should not consider these connections generically, but need to address the specific types of connections. In particular, fill and spill promotes external water exports while fill and merge favors internal storage. The behaviors of such intermittent connections will likely be accentuated under a future with more frequent and severe climate extremes. Under the Safe and Sustainable Water Resources National Program, work is being done to qu

  19. Effects of different surface conditioning methods on the bond strength of composite resin to amalgam.

    PubMed

    Ozcan, M; Koolman, C; Aladag, A; Dündar, M

    2011-01-01

    Repairing amalgam restorations with composite resins using surface conditioning methods is a conservative treatment approach. This study investigated the effects of different conditioning methods that could be used for repair of amalgam fractures. Amalgam (N=96) was condensed into cavities within autopolymerizing polymethylmethacrylate (PMMA), and the exposed surface of each specimen (diameter, 6 mm; thickness, 2 mm) was ground finished. The specimens were randomly divided into nine experimental groups (n=12 per group), depending on the conditioning method used. The control group had natural central incisors with amalgam (n=12). The combination of the following conditioning methods was tested: silicacoating (Sc), sandblasting (Sb), metal primers, coupling agents, fiber (Fb) application, and opaquers (O). Five types of silanes, metal primers, or adhesives (Visiobond [V], Porcelain Photobond [PP], Alloy Primer [AP], Unibond sealer [Us], ESPE-Sil [ES]), and four opaquers, namely, Clearfil St Opaquer (CstO), Sinfony (S), Miris (M), and an experimental Opaquer (EO-Cavex), were used. The groups were as follows: group 1, Sc+ES+S+V; group 2, Sc+ES+CstO+V; group 3, Sc+ES+M+V; group 4, Sc+ES+EO+V; group 5, Sb+AP+S; group 6, Sb+AP+PP+CstO; group 7, Sc+ES+S+Fb+V+Fb; group 8-control, SC+ES+V; and group 9, Etch+Sc+ES+S+Us. One repair composite was used for all groups (Clearfil Photo Bond Posterior, Kuraray, Tokyo, Japan). Shear bond strengths (SBSs) (MPa ± SD) were evaluated after 5 weeks of water storage (analysis of variance [ANOVA], Tukey honestly significant differences [HSD], α=0.05). Group 1 exhibited significantly higher values (35.5 ± 4.1) than were seen in group 4 (19.4 ± 8.9), group 6 (19.1 ± 7.8), and group 8 (20.1 ± 4.1) (p<0.05). Group 9 exhibited significantly lower values (8.3 ± 3.4) than were noted in groups 1 to 3 (35.5 ± 4.1; 27 ± 12.5; 24.4 ± 5.1, respectively) (p<0.05). Group 7 (16.4 ± 5.9) showed significantly lower values than were observed in

  20. Pathways in dental public health.

    PubMed

    Silverstein, Steven J

    2005-07-01

    Dental public health is one of the nine specialties of dentistry recognized by the American Dental Association Commission on Dental Accreditation. Dental public health has been defined as the "science and art of preventing and controlling dental diseases and promoting dental health through organized community efforts. It is that form of dental practice which serves the community as a patient rather than as an individual. It is concerned with the dental health education of the public, with applied dental research, and with the administration of group dental care programs as well as the prevention and control of dental diseases on a community basis." This article will describe the many career and educational pathways dentists may follow to become irvolved in the practice of dental public health.

  1. International dental standards.

    PubMed

    Jones, Derek W

    2007-09-22

    International dental standards are vital in maintaining the safety and quality of both the products and materials used by dental professionals and the many oral health products used by members of the general public, yet many dentists will be unaware of the role standards play in their daily practice. In this article, Derek W. Jones outlines the vital work of the International Standards Organization and highlights how standards pervade nearly every dental procedure.

  2. Dental radiology for children

    SciTech Connect

    Myers, D.R.

    1984-01-01

    The benefit for the child from the judicious use of diagnostic dental radiography is improved dental health. The risk to the child from dental diagnostic radiation exposure appears to be extremely low. Despite the low risk, the dentist must minimize the child's exposure to ionizing radiation by using sound clinical judgment to determine what radiographs are necessary and to provide children with optimal protection from ionizing radiation.

  3. Noise levels in a dental teaching institute - A matter of concern!

    PubMed Central

    Singh, Simarpreet; Singh, Gurminder; Sharma, Sumit; Kaur, Amarinder

    2012-01-01

    Objective: To measure and assess the noise levels produced by various dental equipments in different areas of a dental institution and to recommend improvements if noise levels are not within permissible limits. Material and Methods: Sound levels were measured at three different areas of a dental institution where learning and teaching activities are organized. The sound level was measured using a sound level meter known as ‘decibulolmeter’. In each area the noise level was assessed at two positions-one, at 6 inches from the operators ear and second, at the chairside instrument trolley. Noise levels were also assessed from a central location of the clinic area when multiple equipments were in operation simultaneously. Results: Dental laboratory machine, dental hand-piece, ultrasonic scalers, amalgamators, high speed evacuation, and other items produce noise at different sound levels which is appreciable. The noise levels generated varied between 72.6 dB in pre-clinics and 87.2 dB in prosthesis laboratory. The results are comparable to the results of other studies which are conducted elsewhere. Although the risk to the dentists is lesser, but damage to the hearing is possible over prolonged periods. Conclusion: Higher noise levels are potentially hazardous to the persons working in such environments especially in the laboratory areas where noise levels are exceeding the permissible limits. Key words:Noise level, equipment, hearing loss, risk, working areas. PMID:24558544

  4. Dental erosion, summary.

    PubMed

    ten Cate, J M; Imfeld, T

    1996-04-01

    Although reports on dental erosion have always appeared in the dental literature, there is currently a growing interest among researchers and clinicians. Potential risk factors for dental erosion are changed lifestyle and eating patterns, with increased consumption of acidic foods and beverages. Various gastrointestinal and eating disorders expose the dentition to frequent contacts with very acidic gastric content, which may lead to erosion. Whether these factors indeed lead, on a population scale, to a higher prevalence and incidence of erosion is yet to be established. This article summarizes the different aspects of the prevalence, pathology, etiology, assessment, prevention and treatment of dental erosion, and concludes with recommendations for future research.

  5. Dental Implant Systems

    PubMed Central

    Oshida, Yoshiki; Tuna, Elif B.; Aktören, Oya; Gençay, Koray

    2010-01-01

    Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities. PMID:20480036

  6. Amalgam tattoo: report of an unusual clinical presentation and the use of energy dispersive X-ray analysis as an aid to diagnosis

    SciTech Connect

    McGinnis, J.P. Jr.; Greer, J.L.; Daniels, D.S.

    1985-01-01

    An unusual appearing gingival amalgam pigmentation (amalgam tattoo) that completely surrounded the maxillary right first premolar in a 13-year-old boy is presented. Because of the wide distribution and apparent clinical progression of the discoloration, an excisional biopsy was performed. The histopathologic diagnosis of amalgam pigmentation was confirmed in paraffin sections by energy dispersive X-ray microanalysis. Silver, tin, and mercury were detected in the specimen.

  7. Taekwondo coaches knowledge about prevention and management of dental trauma.

    PubMed

    Vidović, Dina; Gorseta, Kristina; Bursac, Danijel; Glavina, Domagoj; Skrinjarić, Tomislav

    2014-06-01

    The aim of this study was to assess level of knowledge about prevention and dental trauma management among taekwondo coaches in Croatia. The questionnaire submitted to the taekwondo coaches contained 16 items about dental trauma prevention and management. The questionnaires were filled in by 131 taekwondo coaches; 28 females and 103 males. Descriptive statistics was used to describe and analyze the obtained data. The coaches were familiar with dental injuries in high percentage: 41 (31.3%) have observed dental injury and 36 (27.5%) have experienced a dental injury themselves. Eight of them had tooth avulsion, fourteen crown fracture, and eight had tooth luxation. About half of all interviewed coaches 68 (52.7%) were aware of the possibility of replanting avulsed teeth. Twenty six (19.8%) were familiar with the tooth rescue kit. Only 99 out of 131 coaches (75.6%) have used a mouthguard. The obtained results show low knowledge about possibilities for prevention of dental trauma. Insufficient use of mouthguards in this contact sport requires more attention of dentists and coaches education about dental trauma prevention.

  8. The Brisbane Dental Hospital Building: "The Palace" An Era Ends.

    PubMed

    Akers, Harry F; Foley, Michael A; Brown, John P

    2015-01-01

    Constitutional, educational, humanitarian and political considerations underpinned the design and construction of the Brisbane Dental Hospital Building, often colloquially referred to as "The Palace." The Queensland Heritage Council's listing of the Brisbane Dental Hospital Building on The Queensland Heritage Register in 1999 confirms the cultural significance of Nowland's architectural signature, the historical importance of the Wickham Park precinct and prior students' connection with the building. Influences on decisions determining the location, grand design and timing of construction of the Brisbane Dental Hospital Building emanated from a far bigger and largely unrecorded political picture. The authors argue that the political context in two tiers of government, the timing and nature of the proposal, town planning issues, the exigencies of the caries epidemic and Forgan Smith's post-Depression economic reconstruction across Queensland underpinned the project. Hanlon's personal attributes and disdain for the autonomy of the dental profession, together with his desire to reform dental education and to establish statewide government-administred dental clinics, were also relevant. Accordingly, the BDHD portrayed aspiration, purpose, symbolism, and vision. This paper, essentially an integration of dental and mainstream history, assembles and analyzes hitherto scattered and unpublished evidence to fill a gap in the current literature.

  9. Comparison of Dental Explorers and CPI-probes in Diagnosing Dental Caries.

    PubMed

    Ishizuka, Yoichi; Maki, Yoshinobu; Kagami, Noriaki; Satou, Ryouichi; Sugihara, Naoki

    2015-01-01

    The primary aim of the present study was to compare efficiency in detecting suspected caries requiring observation (CO) and decayed teeth (DT) between dental explorers and Community Periodontal Index (CPI)-probes in school dental examinations and evaluate the effect of their respective use on Decayed, Missing, Filled Teeth (DMFT) Index scores. A total of 126 elementary and high school students were examined. All the clinical findings were obtained by a pair of trained dentists examining each student at routine annual school dental examinations. A dental explorer or CPI-probe and dental mirror were used for the examination. One dentist used the dental explorer, while the other used the CPI-probe. The choice of which instrument to use by the first dentist to examine the student was made at random. A comparison of the explorers and CPI-probes revealed that the numbers of patients and permanent teeth classified as CO were greater with the former in 6th-grade elementary and high school students (p<0.05). The Kappa value for CO and DT was 0.560 for 6th-grade elementary school and 0.846 for high school students. All DMFT scores were higher with the explorers than with the CPI-probes in the 6th-grade elementary school students. No significant difference was observed between the explorers and CPI-probes in any of the DMFT scores in any group, however. The present results indicate that as long as the low rate of caries in Japanese school children is maintained, the epidemiological data on this disease should not show any significant change if a CPI-probe is used instead of an explorer in school dental examinations.

  10. Experiences of dental care: what do patients value?

    PubMed Central

    2012-01-01

    Background Dentistry in Australia combines business and health care service, that is, the majority of patients pay money for tangible dental procedures such as fluoride applications, dental radiographs, dental fillings, crowns, and dentures among others. There is evidence that patients question dentists’ behaviours and attitudes during a dental visit when those highly technical procedures are performed. However, little is known about how patients’ experience dental care as a whole. This paper illustrates the findings from a qualitative study recently undertaken in general dental practice in Australia. It focuses on patients’ experiences of dental care, particularly on the relationship between patients and dentists during the provision of preventive care and advice in general dental practices. Methods Seventeen patients were interviewed. Data analysis consisted of transcript coding, detailed memo writing, and data interpretation. Results Patients described their experiences when visiting dental practices with and without a structured preventive approach in place, together with the historical, biological, financial, psychosocial and habitual dimensions of their experience. Potential barriers that could hinder preventive activities as well as facilitators for prevention were also described. The offer of preventive dental care and advice was an amazing revelation for this group of patients as they realized that dentists could practice dentistry without having to “drill and fill” their teeth. All patients, regardless of the practice they came from or their level of clinical risk of developing dental caries, valued having a caring dentist who respected them and listened to their concerns without “blaming” them for their oral health status. These patients complied with and supported the preventive care options because they were being “treated as a person not as a patient” by their dentists. Patients valued dentists who made them aware of existing

  11. Educational material of dental anatomy applied to study the morphology of permanent teeth.

    PubMed

    Siéssere, Selma; Vitti, Mathias; de Sousa, Luiz Gustavo; Semprini, Marisa; Regalo, Simone Cecílio Hallak

    2004-01-01

    The purpose of this report is to present educational material that would allow the dental student to learn to easily identify the morphologic characteristics of permanent teeth, and how they fit together (occlusion). In order to do this, macro models of permanent teeth with no attrition were carved in wax and later molded with alginate. These molds were filled with plaster, dental stone and/or cold-cured acrylic resin. The large individual dental stone tooth models were mounted on a wax base, thus obtaining maxillary and mandibular arches which were occluded. These dental arches were molded with plaster or dental stone. The authors suggest that these types of macro models allow an excellent visualization of the morphologic characteristics of permanent teeth and occlusion. Dental students are able to carve the permanent dentition in wax with great facility when they can observe macro models.

  12. Discrimination of tooth layers and dental restorative materials using cutting sounds.

    PubMed

    Zakeri, Vahid; Arzanpour, Siamak; Chehroudi, Babak

    2015-03-01

    Dental restoration begins with removing carries and affected tissues with air-turbine rotary cutting handpieces, and later restoring the lost tissues with appropriate restorative materials to retain the functionality. Most restoration materials eventually fail as they age and need to be replaced. One of the difficulties in replacing failing restorations is discerning the boundary of restorative materials, which causes inadvertent removal of healthy tooth layers. Developing an objective and sensor-based method is a promising approach to monitor dental restorative operations and to prevent excessive tooth losses. This paper has analyzed cutting sounds of an air-turbine handpiece to discriminate between tooth layers and two commonly used restorative materials, amalgam and composite. Support vector machines were employed for classification, and the averaged short-time Fourier transform coefficients were selected as the features. The classifier performance was evaluated from different aspects such as the number of features, feature scaling methods, classification schemes, and utilized kernels. The total classification accuracies were 89% and 92% for cases included composite and amalgam materials, respectively. The obtained results indicated the feasibility and effectiveness of the proposed method.

  13. The effect of occupational exposure to mercury vapour on the fertility of female dental assistants.

    PubMed Central

    Rowland, A S; Baird, D D; Weinberg, C R; Shore, D L; Shy, C M; Wilcox, A J

    1994-01-01

    Exposure to mercury vapour or inorganic mercury compounds can impair fertility in laboratory animals. To study the effects of mercury vapour on fertility in women, eligibility questionnaires were sent to 7000 registered dental assistants in California. The final eligible sample of 418 women, who had become pregnant during the previous four years, were interviewed by telephone. Detailed information was collected on mercury handling practices and the number of menstrual cycles without contraception it had taken them to become pregnant. Dental assistants not working with amalgam served as unexposed controls. Women with high occupational exposure to mercury were less fertile than unexposed controls. The fecundability (probability of conception each menstrual cycle) of women who prepared 30 or more amalgams per week and who had five or more poor mercury hygiene factors was only 63% of that for unexposed women (95% CI 42%-96%) after controlling for covariates. Women with low exposure were more fertile, however, than unexposed controls. Possible explanations for the U shaped dose response and limitations of the exposure measure are discussed. Further investigation is needed that uses biological measures of mercury exposure. PMID:8124459

  14. Education About Dental Hygienists' Roles in Public Dental Prevention Programs: Dental and Dental Hygiene Students' and Faculty Members' and Dental Hygienists' Perspectives.

    PubMed

    Pervez, Anushey; Kinney, Janet S; Gwozdek, Anne; Farrell, Christine M; Inglehart, Marita R

    2016-09-01

    In 2005, Public Act No. 161 (PA 161) was passed in Michigan, allowing dental hygienists to practice in approved public dental prevention programs to provide services for underserved populations while utilizing a collaborative agreement with a supervising dentist. The aims of this study were to assess how well dental and dental hygiene students and faculty members and practicing dental hygienists have been educated about PA 161, what attitudes and knowledge about the act they have, and how interested they are in additional education about it. University of Michigan dental and dental hygiene students and faculty members, students in other Michigan dental hygiene programs, and dental hygienists in the state were surveyed. Respondents (response rate) were 160 dental students (50%), 63 dental hygiene students (82%), 30 dental faculty members (26%), and 12 dental hygiene faculty members (52%) at the University of Michigan; 143 dental hygiene students in other programs (20%); and 95 members of the Michigan Dental Hygienists' Association (10%). The results showed that the dental students were less educated about PA 161 than the dental hygiene students, and the dental faculty members were less informed than the dental hygiene faculty members and dental hygienists. Responding dental hygiene faculty members and dental hygienists had more positive attitudes about PA 161 than did the students and dental faculty members. Most of the dental hygiene faculty members and dental hygienists knew a person providing services in a PA 161 program. Most dental hygiene students, faculty members, and dental hygienists wanted more education about PA 161. Overall, the better educated about the program the respondents were, the more positive their attitudes, and the more interested they were in learning more.

  15. Dental Laboratory Technician.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document, which is designed for use in developing a tech prep competency profile for the occupation of dental laboratory technician, lists technical competencies and competency builders for 13 units pertinent to the health technologies cluster in general and 8 units to the occupation of dental laboratory technician. The following skill areas…

  16. Dental Assisting Program Guide.

    ERIC Educational Resources Information Center

    Georgia Univ., Athens. Dept. of Vocational Education.

    This program guide contains the standard dental assisting curriculum for technical institutes in Georgia. The curriculum encompasses the minimum competencies required for entry-level dental assistants, and includes job skills in the technical areas of preventive dentistry; four-handed dentistry; chairside assisting with emphasis in diagnostics,…

  17. Clinical feline dental radiography.

    PubMed

    Lemmons, Matthew

    2013-05-01

    Dental radiography is a necessary diagnostic modality in small animal practice. It is not possible to accurately assess and diagnose tooth resorption, periodontal disease, endodontic disease, neoplasia and injury without it. Dental radiography is also necessary for treatment and assessment of the patient postoperatively.

  18. Dental Charting. Student's Manual.

    ERIC Educational Resources Information Center

    Weaver, Trudy Karlene; Apfel, Maura

    This manual is part of a series dealing with skills and information needed by students in dental assisting. The individualized student materials are suitable for classroom, laboratory, or cooperative training programs. This student manual contains four units covering the following topics: dental anatomical terminology; tooth numbering systems;…

  19. Workbook for Dental Records.

    ERIC Educational Resources Information Center

    Carpenter, Corinne K.; Volpe, Margaret E.

    This workbook contains l8 units of instruction for dental assistant students, each designed to give students practical experience in completing forms that simulate realistic situations in a dental office. Units are: (1) The Appointment Record, (2) The Recall System, (3) Clinical Records, (4) Estimates, (5) Daily Record Sheet, (6) Patient's…

  20. Dental Fear Among University Employees: Implications for Dental Education.

    ERIC Educational Resources Information Center

    Kaakko, Tarja; Milgrom, Peter; Coldwell, Susan E.; Getz, Tracy; Weinstein, Philip; Ramsay, Douglas S.

    1998-01-01

    A survey of 270 University of Washington permanent employees who were potential candidates for teaching clinics, found dental anxiety prevalent, correlating with poorer perceived dental health, longer intervals between dental appointments, higher frequency of past fear behaviors, more physical symptoms during last dental injection, and more…

  1. Dental equipment test during zero-gravity flight

    NASA Technical Reports Server (NTRS)

    Young, John; Gosbee, John; Billica, Roger

    1991-01-01

    The overall objectives of this program were to establish performance criteria and develop prototype equipment for use in the Health Maintenance Facility (HMF) in meeting the needs of dental emergencies during space missions. The primary efforts during this flight test were to test patient-operator relationships, patent (manikin) restraint and positioning, task lighting systems, use and operation of dental rotary instruments, suction and particle containment system, dental hand instrument delivery and control procedures, and the use of dental treatment materials. The initial efforts during the flight focused on verification of the efficiency of the particle containment system. An absorptive barrier was also tested in lieu of the suction collector. To test the instrument delivery system, teeth in the manikin were prepared with the dental drill to receive restorations, some with temporary filling materials and another with definitive filling material (composite resin). The best particle containment came from the combination use of the laminar-air/suction collector in concert with immediate area suction from a surgical high-volume suction tip. Lighting in the treatment area was provided by a flexible fiberoptic probe. This system is quite effective for small areas, but for general tasks ambient illumination is required. The instrument containment system (elastic cord network) was extremely effective and easy to use. The most serious problem with instrument delivey and actual treatment was lack of time during the microgravity sequences. The restorative materials handled and finished well.

  2. Antibacterial effect of selected root-end filling materials.

    PubMed

    Eldeniz, Ayce Unverdi; Hadimli, Hasan Huseyin; Ataoglu, Hanife; Orstavik, Dag

    2006-04-01

    The purpose of this study was to evaluate the antibacterial activity of leachable components of selected root-end filling materials: amalgam, ProRoot MTA (mineral trioxide aggregate), Intermediate Restorative Material (IRM), Super Bond C&B, Geristore, Dyract, Clearfil APX composite with SE Bond, or Protect Bond. The direct contact test (DCT) with Staphylococcus aureus, Enterococcus faecalis, and Pseudomonas aeruginosa, was used. The materials were tested immediately after application to the microtiter wells (fresh samples) and after setting for 3 days (set samples). Ten microliters of bacterial suspension was added to each well for direct contact with each material for 1 h at 37 degrees C. Growth of surviving bacteria was then measured in a microplate spectrophotometer hourly at 620 nm for 15 h. Twelve uncoated wells using identical inoculum size served as positive controls. The data obtained at the end of 15 h was subjected to one-way ANOVA and post hoc comparisons were done using Tamhane's T2 test. Fresh samples of all materials showed a 3-h delay in exponential growth of both E. faecalis and S. aureus, and a 5-h delay in growth of P. aeruginosa. Set samples of IRM and ProRoot MTA cements showed generally greater antibacterial activity than the other materials: both completely inhibited P. aeruginosa, and both delayed or limited growth of E. faecalis. The DCT, by being quantitative and virtually independent of solubility and diffusion, was found suitable to assay solid root-end filling materials. IRM and ProRoot MTA were generally more potent inhibitors of bacterial-growth than the other tested materials.

  3. Determination of lead and cadmium in seawater using a vibrating silver amalgam microwire electrode.

    PubMed

    Bi, Zhaoshun; Salaün, Pascal; van den Berg, Constant M G

    2013-03-26

    Silver amalgamated electrodes are a good substrate to determine lead (Pb) and cadmium (Cd) in seawater because they have properties similar to mercury but without the free mercury (Hg). Here a silver amalgamated microwire (SAM) electrode is optimised for the determination of Pb and Cd in coastal waters and uncontaminated ocean waters. The SAM was vibrated during the deposition step to increase the sensitivity, and electroanalytical parameters were optimised. The Hg coating required plating from a relatively concentrated (millimolar) solution, much greater (500×) than used for instance to coat glassy carbon electrodes. However, the coating on the ex situ amalgamated electrode was found to be stable and could be used for up to a week to determine trace levels of Pb in seawater of natural pH. The limit of detection square-wave ASV (50 Hz) using the pre-plated SAM electrode was 8 pM Pb using a 1-min plating time at pH 4.5. The limit of detection in pH 2 seawater was 4 pM using a 5-min plating time, and it was 12 pM using a 10-min plating time at natural pH in the presence of air, using a square-wave frequency of 700 Hz. The vibrating SAM electrode was tested on the determination of Pb in reference seawater samples from the open Atlantic (at the 20 pM level), Pacific, and used for a study of Pb in samples collected over 24 h in Liverpool Bay (Irish Sea).

  4. Microleakage in conventional and bonded amalgam restorations: influence of cavity volume.

    PubMed

    da Silva, Adriana Fernandes; Piva, Evandro; Demarco, Flávio Fernando; Correr Sobrinho, Lourenço; Osinga, Prudêncio Willy Rodo

    2006-01-01

    This study verified the relationship between the volume and microleakage of conventional and bonded amalgam restorations. Also, the microleakage influence of intermediate materials, substrates and the direction of sectioning was investigated. Fifty-six bovine incisors were selected. Standard Class V cavities were prepared in buccal and lingual surfaces. For each tooth, two cavity sizes were prepared, corresponding to two cavity volumes: one larger (A) and the other smaller (B). The cervical wall was located in cementum/dentin and the incisal wall in enamel. The teeth were distributed in four groups (n=28) according to the intermediate material employed (glass-ionomer cement, resin cement, adhesive system and copal varnish-control). The materials were applied following manufacturers' directions. After restoration, the teeth were submitted to thermal cycling. They were then immersed in a dye solution and sectioned in two directions inciso-cervical (IC) and mesio-distal (MD) sections to evaluate the microleakage. Data were subjected to non-parametric statistical analysis (Wilcoxon's paired test and Kruskal-Wallis test). No significant difference was found between the two cavity sizes. Leakage in enamel was statistically lower than in the cementum/dentin interface (p < 0.05). In some situations, glass-ionomer or resin cement lined amalgam restorations presented less dye leakage than copal varnish lined restorations (p < 0.05). No significant difference was observed in microleakage between IC or MD sectioning. Within the limitations of this study, it was concluded that cavity size and direction of section were not significant factors for microleakage, while substrate and intermediate materials had a significant effect on the sealing ability in amalgam restorations.

  5. Use of copper shavings to remove mercury from contaminated groundwater or wastewater by amalgamation.

    PubMed

    Huttenloch, Petra; Roehl, Karl Ernst; Czurda, Kurt

    2003-09-15

    The efficacy of copper shavings (Cu(0)) for the removal of Hg2+ from aqueous solution by amalgamation is demonstrated. Two kinds of copper shavings were investigated: (a) chemically processed shavings (Fluka) and (b) recycled shavings from scrap metal. Batch sorption experiments yielded very high retardation coefficients of 28 850-82 830 for the concentration range studied (1-10 000 microg/L Hg2+ dissolved in distilled water or in a 0.01 M CaCl2 matrix solution). Sorption data were well-described bythe Freundlich isotherm equation. Kinetic batch sorption experiments showed that 96-98% of Hg2+ was removed within 2 h. Column experiments were performed with a mercury solution containing 1000 microg/L Hg in a 0.01 M CaCl2 matrix with a flow rate of 0.5 m/d. No mercury breakthrough (c/c(0) = 0.5) could be detected after more than 2300 percolated pore volumes, and the high retardation coefficients determined in the batch studies could be confirmed. Copper was released from the shavings due to the amalgamation process and to copper corrosion by oxygen, resulting in concentrations of mobilized copper of 0.2-0.6 mg/L. Due to their high efficiency in removing Hg2+ from aqueous solution, the use of copper shavings for the removal of mercury from contaminated water is suggested, employing a sequential system of mercury amalgamation followed by the removal of mobilized copper by an ion exchanger such as zeolites. Possible applications could be in environmental technologies such as wastewater treatment or permeable reactive barriers for in situ groundwater remediation.

  6. [The corrosion behavior of antimony in a Ag-Sn-Cu-Sb amalgam].

    PubMed

    Weiland, M; Borrmann, S; Nossek, H

    1989-01-01

    Specimen of amalgam containing antimony were stored in solutions with different pH and different content of rhodanide until 21 days. The most antimony were solved within 24 hours. After 7 days an increase of the antimony concentration were not observed in physiological pH. An inhibition of corrosion by rhodanide existed only after incubation from 21 days. The quantity of antimony (10-21 micrograms) were analysed by mean of atomic absorption spectroscopy. It represent not a risk for the health. The natural presence of this element in environment and in human body is discussed to the analysed quantity of solved antimony.

  7. Structural chemistry and number theory amalgamized: crystal structure of Na11Hg52.

    PubMed

    Hornfeck, Wolfgang; Hoch, Constantin

    2015-12-01

    The recently elucidated crystal structure of the technologically important amalgam Na11Hg52 is described by means of a method employing some fundamental concept of number theory, namely modular arithmetical (congruence) relations observed between a slightly idealized set of atomic coordinates. In combination with well known ideas from group theory, regarding lattice-sublattice transformations, these allow for a deeper mutual understanding of both and provide the structural chemist with a slightly different kind of spectacles, thus enabling a distinct viw on complex crystal structures in general.

  8. Predictors of Job Satisfaction in Dental Professionals of the Bosnia and Herzegovina Federation

    PubMed Central

    Muhic, Edin; Plancak, Darije; Muhic, Asja

    2016-01-01

    Introduction Working in a healthy work environment is the ultimate goal of every employee. Dentistry is a stressful career, and the reasons for dissatisfaction are numerous. Aim The aim of this study was to determine the factors of work satisfaction in dental professionals of the Bosnia and Herzegovina Federation. Materials and methods A total of 134 dental professionals selected randomly from the Registry of Dental Chamber of Bosnia and Herzegovina Federation were included in the study. All of them filled out the Demographic Questionnaire and Job Satisfaction Scale (JSS). Results An increase in the influence of work on the quality of life as well as an increase in its frequency results in leaving the job and significantly reducing the overall job satisfaction. General dental practitioners are significantly more satisfied as compared with specialists. Significant predictors of the job satisfaction are employment status, type of the practice, and availability of dental assistants. General dental practitioners with a dental assistant employed at a private practice are more likely to be satisfied with their jobs. Conclusions Employment status, practice type and availability of dental assistants are significant predictors of job satisfaction. General dental practitioners working in a private practice with a dental assistant are most likely to be satisfied. PMID:27847395

  9. Health Instruction Packages: Permanent Teeth, Dental Deposits, and Dental Instruments. Dientes Permanentes, Depositos Dentales y Instrumentos Dentales.

    ERIC Educational Resources Information Center

    Lind, Patricia; Germano, Catherine

    These five learning modules use text interspersed with illustrations and reinforcement exercises to instruct dental aide and dental hygiene students about jaw bones and gums, dental deposits, and dental instruments. The first four modules were prepared by Patricia Lind in both Spanish and English. "The Gum and Bone of Permanent Teeth"…

  10. Comparison of the dental education systems in Korea and Japan.

    PubMed

    Heo, Seok-Mo; Kim, K J; Kawamura, Makoto; Komabayashi, Takashi

    2004-04-01

    In recent years, international relationships in dentistry have grown stronger through journals, books, academies, seminars, researcher exchanges and so forth. Korea and Japan are neighbours in East Asia. However, no comparison of the dental education systems of the two countries has been published. Therefore, the authors have provided the present comparison to promote mutual understanding and to familiarise dentists around the world with dental education in these two countries. The number of dentists, life expectancy at birth, and number of decayed, missing, and filled teeth (DMFT) at age 12 years in Korea and Japan are summarised.

  11. Long-term patterns of dental attendance and caries experience among British adults: a retrospective analysis.

    PubMed

    Aldossary, Arwa; Harrison, Victoria E; Bernabé, Eduardo

    2015-02-01

    There is inconclusive evidence on the value of regular dental attendance. This study explored the relationship between long-term patterns of dental attendance and caries experience. We used retrospective data from 3,235 adults, ≥ 16 yrs of age, who participated in the Adult Dental Health Survey in the UK. Participants were classified into four groups (always, current, former, and never regular-attenders) based on their responses to three questions on lifetime dental-attendance patterns. The association between dental-attendance patterns and caries experience, as measured using the decayed, missing, or filled teeth (DMFT) index, was tested in negative binomial regression models, adjusting for demographic (sex, age, and country of residence) and socio-economic (educational attainment, household income, and social class) factors. A consistent pattern of association between long-term dental attendance and caries experience was found in adjusted models. Former and never regular-attenders had a significantly higher DMFT score and numbers of decayed and missing teeth, but fewer filled teeth, than always regular-attenders. No differences in DMFT or its components were found between current and always regular-attenders. The findings of this study show that adults with different lifetime trajectories of dental attendance had different dental statuses.

  12. In vitro comparative study of sealing ability of Diadent BioAggregate and other root-end filling materials

    PubMed Central

    El Sayed, MA; Saeed, MH

    2012-01-01

    Aim: This in vitro study evaluated and compared sealing ability of Diadent BioAggregate (DBA) as a new root-end filling material (REFM) versus amalgam, intermediate restorative material (IRM) and white mineral trioxide aggregate (WMTA). Materials and Methods: Crowns of sixty extracted human maxillary incisors were sectioned at the cemento-enamel junction (CEJ). All the roots were instrumented and obturated with gutta-percha and resin sealer. Obturated roots were divided randomly into 2 control groups and 4 experimental groups of 10 samples each. In the negative control group (group I), roots were kept without any further preparation. In the positive and experimental groups roots, were apically resected and root-end cavities were prepared and filled with: (a) gutta-percha (group 2-positive control group); (b) amalgam (group 3); (c) IRM (group 4); (d) WMTA (group 5); (e) DBA (group 6). Apical leakage was assessed using dye penetration technique. Data were submitted to statistical analysis by the one-way analysis of variance (ANOVA) and Tukey's test. Results: Significant difference of sealing ability was found among 4 tested groups. DBA followed by MTA showed the highest sealing ability. Conclusions: DBA with its high sealing ability can be considered a possible alternative to MTA. PMID:22876012

  13. Dental Compressed Air Systems.

    DTIC Science & Technology

    1992-03-01

    I AL-TR-IWI-0uuu AD-A249 954 DENTAL COMPRESSED AIMYTM R Curtis D. Weyrmuch, Mejor, USAP, D Samuel P.Dvs iueatclpi SF.O N AEROSPACE MwaEDIN mwr~ComA G...FUNDING NUMBERS Dental Compressed Air Systems PE - 87714F PR - 7350 TA - 22 D. Weyrauch WU - XX Samuel P. Davis George W. Gaines 7. PERFORMING...words) The purpose of this report is to update guidelines on dental compressed air systems (DCA). Much of the information was obtained from a survey

  14. Standing equine dental surgery.

    PubMed

    Menzies, Robert A; Easley, Jack

    2014-04-01

    Dental surgeries refer to procedures that affect the dental tissues or their supporting structures. With the development of specific, efficacious, and conservative treatments, morbidity risks have been lowered and chances of benefiting the health of equids improved. Advances in quality of sedation, analgesia, and locoregional anesthesia allow a majority of dental surgeries to be performed in the standing patient. This update focuses on an orthograde endodontic technique, a minimally invasive buccotomy technique, with the potential to combine it with a transbuccal screw extraction technique, and revisits the AO pinless external fixator for fractures of the body of the mandible.

  15. Feline dental disease.

    PubMed

    Frost, P; Williams, C A

    1986-09-01

    Periodontal disease and chronic gingivitis/stomatitis are the most common feline dental diseases. With routine dental care and increased emphasis on home oral hygiene, these diseases can be controlled. Cats can be seen with a number of other dental disorders, and improved treatment methods such as restorations of early subgingival resorptive lesions, endodontic therapy, and orthodontic therapy can be performed successfully. More study and research are necessary about the gingivitis/stomatitis syndrome and subgingival resorptive lesions so that improved prevention and treatment recommendations can be made.

  16. Dental composite resins: measuring the polymerization shrinkage using optical fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Ottevaere, H.; Tabak, M.; Chah, K.; Mégret, P.; Thienpont, H.

    2012-04-01

    Polymerization shrinkage of dental composite materials is recognized as one of the main reasons for the development of marginal leakage between a tooth and filling material. As an alternative to conventional measurement methods, we propose optical fiber Bragg grating (FBG) based sensors to perform real-time strain and shrinkage measurements during the curing process of dental resin cements. We introduce a fully automated set-up to measure the Bragg wavelength shift of the FBG strain sensors and to accurately monitor the linear strain and shrinkage of dental resins during curing. Three different dental resin materials were studied in this work: matrix-filled BisGMA-based resins, glass ionomers and organic modified ceramics.

  17. Plasmonic detection of mercury via amalgam formation on surface-immobilized single Au nanorods

    PubMed Central

    Schopf, Carola; Martín, Alfonso; Iacopino, Daniela

    2017-01-01

    Abstract Au nanorods were used as plasmonic transducers for investigation of mercury detection through a mechanism of amalgam formation at the nanorod surfaces. Marked scattering color transitions and associated blue shifts of the surface plasmon resonance peak wavelengths (λ max) were measured in individual nanorods by darkfield microscopy upon chemical reduction of Hg(II). Such changes were related to compositional changes occurring as a result of Hg–Au amalgam formation as well as morphological changes in the nanorods’ aspect ratios. The plot of λ max shifts vs. Hg(II) concentration showed a linear response in the 10–100 nM concentration range. The sensitivity of the system was ascribed to the narrow width of single nanorod scattering spectra, which allowed accurate determination of peak shifts. The system displayed good selectivity as the optical response obtained for mercury was one order of magnitude higher than the response obtained with competitor ions. Analysis of mercury content in river and tap water were also performed and highlighted both the potential and limitation of the developed method for real sensing applications. PMID:28179959

  18. Potential of Brass to Remove Inorganic Hg(II) from Aqueous Solution through Amalgamation.

    PubMed

    Wenke, Axel; Bollen, Anne; Richard, Jan-Helge; Biester, Harald

    2016-06-01

    Brass shavings (CuZn45) were tested for their efficiency to remove Hg(II) from contaminated groundwater through amalgamation. The study was focused on long-term retention efficiency, the understanding of the amalgamation process and kinetics, and influences of filter surface alteration. Column tests were performed with brass filters (thickness 3 to 9 cm) flushed with 1000 μg/L Hg solution for 8 hours under different flow rates (300 to 600 mL/h). Brass filters consistently removed >98% of Hg from solution independent of filter thickness and flow rate. In a long-term experiment (filter thickness 2 cm), Hg retention decreased from 96 to 92% within 2000 hours. Batch and column experiments for studying kinetics of Hg removal indicate ~100% Hg removal from solution within only 2 hours. Solid-phase mercury thermo-desorption analysis revealed that Hg(0) diffusion into the brass surface controls kinetics of mercury retention. Brass surface alteration could be observed, but did not influence Hg retention.

  19. Super (a, d) - Fn - antimagic total labeling for a connected and disconnected amalgamation of fan graphs

    NASA Astrophysics Data System (ADS)

    Dafik, Agustin, Ika Hesti; Khuri Faridatun, N.

    2016-02-01

    All graph in this paper are finite, simple and undirected. Let G = (V (G), E(G)) be a graph of order p and size q. Graph G admits a H-covering, if every edge in E(G) belongs to at least one subgraph of G isomorphic to a given graph H. A graph G is said to be an (a, d)-H-antimagic total labeling if there exist a bijective function f : V (G) ∪ E(G) → {1, 2,…, |V(G)| + |E(G)|} such that for all subgraphs H' isomorphic to H, the total H-weights w(H) = ∑v∈V (H') f (v) + ∑e∈E(H') f (e) form an arithmetic sequence {a, a + d, a + 2d, …, a + (t - 1)d}, where a and d are positive integers and t is the number of all subgraphs H' isomorphic to H. Such a labeling is called a super if the smallest labels appear in the vertices. This paper studies the super (a, d)-Fn-antimagic total labeling for a connected and disconnected amalgamation of fan graphs. We can prove that, for some feasible d, a connected and disconnected amalgamation of fan graphs admit a super (a, d) - Fn-antimagic total labeling.

  20. Economic impact of dental hygienists on solo dental practices.

    PubMed

    Lazar, Vickie F; Guay, Albert H; Beazoglou, Tryfon J

    2012-08-01

    The fact that a significant percentage of dentists employ dental hygienists raises an important question: Are dental practices that utilize a dental hygienist structurally and operationally different from practices that do not? This article explores differences among dental practices that operate with and without dental hygienists. Using data from the American Dental Association's 2003 Survey of Dental Practice, a random sample survey of U.S. dentists, descriptive statistics were used to compare selected characteristics of solo general practitioners with and without dental hygienists. Multivariate regression analysis was used to estimate the effect of dental hygienists on the gross billings and net incomes of solo general practitioners. Differences in practice characteristics--such as hours spent in the practice and hours spent treating patients, wait time for a recall visit, number of operatories, square feet of office space, net income, and gross billings--were found between solo general practitioners who had dental hygienists and those who did not. Solo general practitioners with dental hygienists had higher gross billings. Higher gross billings would be expected, as would higher expenses. However, net incomes of those with dental hygienists were also higher. In contrast, the mean waiting time for a recall visit was higher among dentists who employed dental hygienists. Depending on personal preferences, availability of qualified personnel, etc., dentists who do not employ dental hygienists but have been contemplating that path may want to further research the benefits and opportunities that may be realized.

  1. Mercury and Other Biomedical Waste Management Practices among Dental Practitioners in India

    PubMed Central

    Singh, Raghuwar D.; Jurel, Sunit K.; Tripathi, Shuchi; Agrawal, Kaushal K.; Kumari, Reema

    2014-01-01

    Objectives. The objective of the study was to assess the awareness and performance towards dental waste including mercury management policy and practices among the dental practitioners in North India. Materials and Methods. An epidemiologic survey was conducted among 200 private dental practitioners. The survey form was composed of 29 self-administered questions frame based on knowledge, attitude, and those regarding the practices of dentists in relation to dental health-care waste management. The resulting data were coded and a statistical analysis was done. Results and Discussion. About 63.7% of the dentists were not aware of the different categories of biomedical waste generated in their clinics. Only 31.9% of the dentists correctly said that outdated and contaminated drugs come under cytotoxic waste. 46.2% said they break the needle and dispose of it and only 21.9% use needle burner to destroy it. 45.0% of the dentists dispose of the developer and fixer solutions by letting them into the sewer, 49.4% of them dilute the solutions and let them into sewer and only 5.6% return them to the supplier. About 40.6% of the dentists dispose of excess silver amalgam by throwing it into common bin. Conclusion. It was concluded that not all dentists were aware of the risks they were exposed to and only half of them observe infection control practices. PMID:25162005

  2. Electrochemical action due to short-circuiting of dental alloys. An in vitro and in vivo study.

    PubMed

    Johansson, B I

    1986-01-01

    Metallic materials in the oral cavity cannot be expected to be inert. However, the electrochemical interaction with the environment, may vary considerably. Corrosion of dental metallic materials has been said to cause local, and even general unpleasant effects. Different forms of corrosion and variations in the complex oral milleu make it difficult to estimate and predict the corrosion occurring. Various methods such as the recording of potentials, potential differences and currents have been used to study the corrosion which may occur when metallic restorations or appliances come into contact. However, an improvement should be obtained if data which are more closely related to the ion release due to short-circuiting could be recorded. Calculated currents were related to those directly measured and the knowledge thus obtained was used to design a convenient equipment for clinical registration of the charge transfer between short-circuited restorations or appliances. The equipment was used in a study of patients with disorders/discomfort allegedly caused by corrosion in the oral cavity. Furthermore, the released quantity of tin and the charge transfer between amalgam and gold alloy electrodes were studied both in vitro and clinically. The currents flowing between amalgam and gold alloy electrode couples were compared using different electrolytes. The findings may be summarized as follows: The quantity of tin released in vitro was related to the charge transferred between short-circuited electrodes consisting of a conventional amalgam and a gold alloy and the same tendency could be shown clinically. When electrodes made of a gold alloy and various types of amalgams were short-circuited, the currents recorded were influenced by the composition of the amalgams and of the electrolytes. The equipment constructed admitting measurements of the charge transfer seems to be suitable for an estimation of corrosion due to contacts between metallic restorations/appliances. No

  3. Irrational Fixed Dose Combinations & Need for Intervention: Understanding of Dental Clinicians and Residents

    PubMed Central

    Sharma, Amit; Singh, Vikas; Pilania, Dinesh; Sharma, Yogesh Kumar

    2014-01-01

    Context: There is a growing concern about ever-burgeoning list of irrational fixed dose combinations (FDCs) which have flooded pharmaceutical market recently in India. Till date no structured study has evaluated the level of understanding among the dental clinicians and residents about these concepts. The present study is designed to fulfil that lacuna. Objective: To evaluate the knowledge, attitude and practice, regarding the use of FDCs by the dental residents and dental clinicians in a tertiary care teaching dental hospital. Materials and Methods: The present study was carried out among postgraduate students and dental clinicians working at Rajasthan Dental College, a tertiary care teaching dental hospital, in Jaipur, India. Sixty residents and 77 dental clinicians from the departments of Orthodontics, Prosthodontics, Oral Medicine, Periodontology, Conservative Dentistry & Endodontics, Oral & Maxillofacial Surgery, Pedodontics who gave their informed consent were enrolled. A prevalidated questionnaire regarding knowledge, attitude and prescribing practice of fixed dose combinations was filled up. Data was analysed with suitable statistical tests. Results: Out of the 60 residents and 77 dental clinicians recruited for the study, none of them were aware about all of the advantages and disadvantages of FDCs. On an average, only 47% of residents and 61% dental clinicians were aware of FDC included in WHO Essential Medicines List (EML). Only 47% residents and 58% dental clinicians could recall a single banned FDC in India. Common sources of information about FDCs were Monthly Index of Medical Specialities (MIMS), medical representatives and internet. The most commonly prescribed irrational FDC was diclofenac + paracetamol combination, 42% residents and 41% dental clinicians and residents believed that regular Continuous Medical Education (CMEs) stressing upon rational use of medicine could reduce the magnitude of this problem. Conclusion: It is the need of the hour

  4. An Investigation of Dental Luting Cement Solubility as a Function of the Marginal Gap.

    DTIC Science & Technology

    1988-05-01

    be non-irritating to the dental pulp , and have low solubility. A critical property of luting cement is its solubility in oral fluids. If the cement...25 micron and 100 micron cement margins. In another investigation, hollow orthodontic tubing and the acid etch composite resin technique were used to...evaluate cement solubility. (lbbetson 1985) Hollow orthodontic tubing, with a 0.05 mm diameter, was filled with dental cement and attached to the

  5. Glossary of Dental Terms

    MedlinePlus

    ... of entire communities, and can design and administer large-scale prevention and dental care programs by compiling and analyzing statistics Radiosurgery surgery technique that uses radio waves to produce a pressureless, ...

  6. Interpretation of dental radiographs.

    PubMed

    Woodward, Tony M

    2009-02-01

    Interpretation of dental radiographs is fairly straightforward, with a handful of common patterns making up the majority of pathology. This article covers normal radiographic anatomy, endodontic disease, periodontal disease, neoplastic changes, tooth resorption, caries, and radiographic signs of oral trauma.

  7. Dental Care in Scleroderma

    MedlinePlus

    ... a side effect • Avoid the spiral of depression – depression causes worse oral health and poor oral health worsens depression. Suggestions for your dental appointments: • Tell the dentist ...

  8. American Dental Education Association

    MedlinePlus

    ... ADEA Application Services ADEA AADSAS® ADEA CAAPID® ADEA PASS® ADEA DHCAS® Career Resources DentEd Jobs Placing Ads ... Students & Residents Prospective Students Application Services AADSAS CAAPID PASS DHCAS ADEA AADSAS Applicants Prospective applicants to dental ...

  9. American Dental Hygienists' Association

    MedlinePlus

    ... Working Column Journal of Dental Hygiene Author Guidelines Advertising Subscribe Resources Resources About ADHA About Promo (DO ... Member Benefits Footer Copy Legal Inquiries | Contact Us | Advertising | Media Inquiries | Staff / Board Login ©2012-2017 ADHA. ...

  10. Dental Treatment Considerations

    MedlinePlus

    ... and modifying dental treatment to accommodate altered muscle strength. Appointment Scheduling It is important to realize that ... and take advantage of the typically greater muscle strength during the morning hours. Appointments are best scheduled ...

  11. Dental Caries (Tooth Decay)

    MedlinePlus

    ... form does not collect any actual information. External Web Site Policy This graphic notice ( ) means that you are ... the link. Home Contact Us Viewers and Players Site Map FOIA Web Policies Privacy Policy National Institute of Dental and ...

  12. Diabetes: Dental Tips

    MedlinePlus

    ... form does not collect any actual information. External Web Site Policy This graphic notice ( ) means that you are ... the link. Home Contact Us Viewers and Players Site Map FOIA Web Policies Privacy Policy National Institute of Dental and ...

  13. Filling carbon nanotubes with particles.

    PubMed

    Kim, Byong M; Qian, Shizhi; Bau, Haim H

    2005-05-01

    The filling of carbon nanotubes (CNTs) with fluorescent particles was studied experimentally and theoretically. The fluorescent signals emitted by the particles were visible through the walls of the nanotubes, and the particles inside the tubes were observable with an electron microscope. Taking advantage of the template-grown carbon nanotubes' transparency to fluorescent light, we measured the filling rate of the tubes with particles at room conditions. Liquids such as ethylene glycol, water, and ethylene glycol/water mixtures, laden with 50 nm diameter fluorescent particles, were brought into contact with 500 nm diameter CNTs. The liquid and the particles' transport were observed, respectively, with optical and fluorescence microscopy. The CNTs were filled controllably with particles by the complementary action of capillary forces and the evaporation of the liquid. The experimental results were compared and favorably agreed with theoretical predictions. This is the first report on fluorescence studies of particle transport in carbon nanotubes.

  14. Paleovalley fills: Trunk vs. tributary

    USGS Publications Warehouse

    Kvale, E.P.; Archer, A.W.

    2007-01-01

    A late Mississippian-early Pennsylvanian eustatic sea level drop resulted in a complex lowstand drainage network being eroded across the Illinois Basin in the eastern United States. This drainage system was filled during the early part of the Pennsylvanian. Distinct differences can be recognized between the trunk and tributary paleovalley fills. Fills preserved within the trunk systems tend to be fluvially dominated and consist of bed-load deposits of coarse- to medium-grained sandstone and conglomerate. Conversely, the incised valleys of tributary systems tend to be filled with dark mudstone, thinly interbedded sandstones, and mudstones and siltstones. These finer grained facies exhibit marine influences manifested by tidal rhythmites, certain traces fossils, and macro- and microfauna. Examples of tributary and trunk systems, separated by no more than 7 km (4.3 mi) along strike, exhibit these styles of highly contrasting fills. Useful analogs for understanding this Pennsylvanian system include the Quaternary glacial sluiceways present in the lower Ohio, White, and Wabash river valleys of Indiana (United States) and the modern Amazon River (Brazil). Both the Amazon River and the Quaternary rivers of Indiana have (or had) trunk rivers that are (were) dominated by large quantities of bed load relative to their tributaries. The trunk valley systems of these analogs aggraded much more rapidly than their tributary valleys, which evolved into lakes because depositional rates along the trunk are (were) so high that the mouths of the tributaries have been dammed by bed-load deposits. These Holocene systems illustrate that sediment yields can significantly influence the nature of fill successions within incised valleys independent of rates of sea level changes or proximity to highstand coastlines. Copyright ?? 2007. The American Association of Petroleum Geologists. All rights reserved.

  15. Portable Dental System

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Portable dental system provides dental care in isolated communities. System includes a patient's chair and a dentist's stool, an X-ray machine and a power unit, all of which fold into compact packages. A large yellow "pumpkin" is a collapsible compressed air tank. Portable system has been used successfully in South America in out of the way communities with this back-packable system, and in American nursing homes. This product is no longer manufactured.

  16. Dental physical examination.

    PubMed

    Baker, G J

    1998-08-01

    The objectives of the equine dental physical examination are to detect and quantify oral and dental disorders, to propose and carry out their treatment, and to implement management programs. The veterinarian should be able to offer a prognosis and to detail any future treatment or management plans that may be required. These objectives should take into account the cost of these procedures, and the veterinarian should be prepared to offer a cost-benefit analysis of the problem and the proposed cures.

  17. Dental considerations in anaesthesia

    PubMed Central

    2016-01-01

    Dental trauma as a result of anaesthesia practice is a relevant issue concerning morbidity and litigation. The investigator aimed to consolidate pertinent information on this issue to aid in the redressal of such an occurrence. A review of this relevant literature alongwith the author’s suggestions towards the management of the various kinds of dental trauma sustained as a result of anaesthesia practice is presented. PMID:27974970

  18. TRICARE Dental Programs

    DTIC Science & Technology

    2011-01-01

    enrollee – $1,500 lifetime maximum for orthodontics – Contractor: Delta Dental of California 2011 MHS Conference TRICARE Retiree Dental Program...Benefits Comprehensive benefits 12-month waiting period for crowns, prosthetics and orthodontics No waiting period if enroll within 120 days of...retiring from active duty or transfer to Retired Reserve status from National Guard or Reserve  Orthodontics for children and adults Accident coverage

  19. Dental arch asymmetry

    PubMed Central

    Al-Zubair, Nabil Muhsen

    2014-01-01

    Objective: This study was conducted to assess the dental arch asymmetry in a Yemeni sample aged (18-25) years. Materials and Methods: The investigation involved clinical examination of 1479 adults; only 253 (129 females, 124 males) out of the total sample were selected to fulfill the criteria for the study sample. Study models were constructed and evaluated to measure mandibular arch dimensions. Three linear distances were utilized on each side on the dental arch: Incisal-canine distance, canine-molar distance and incisal-molar distance, which represent the dental arch segmental measurements. Results: When applying “t-test” at P < 0.05, no significant differences were found between the right and left canine-molar, incisal-canine and incisal-molar distances in both dental arches for both sexes. The greater variation (0.30 mm) was observed between right and left canine-molar distance in the maxillary dental arch in male and the smaller (0.04 mm) in the mandibular dental arch between the right and left canine-molar distance in females. Conclusion: The findings of the present study revealed a symmetrical pattern of dental arches, since the right and left sides showed no statistically significant difference. In general, it can be observed that the measurements related to the central incisors and canines have the widest range of reading and give the impression that the location of central incisor and canines to each other and to other teeth is the strongest factor in determining the dental arch asymmetry. PMID:24966774

  20. Gas-Filled Capillary Model

    NASA Astrophysics Data System (ADS)

    Steinhauer, L. C.; Kimura, W. D.

    2006-11-01

    We have developed a 1-D, quasi-steady-state numerical model for a gas-filled capillary discharge that is designed to aid in selecting the optimum capillary radius in order to guide a laser beam with the required intensity through the capillary. The model also includes the option for an external solenoid B-field around the capillary, which increases the depth of the parabolic density channel in the capillary, thereby allowing for propagation of smaller laser beam waists. The model has been used to select the parameters for gas-filled capillaries to be utilized during the Staged Electron Laser Acceleration — Laser Wakefield (STELLA-LW) experiment.

  1. QENS investigation of filled rubbers

    NASA Astrophysics Data System (ADS)

    Triolo, A.; Lo Celso, F.; Negroni, F.; Arrighi, V.; Qian, H.; Lechner, R. E.; Desmedt, A.; Pieper, J.; Frick, B.; Triolo, R.

    The polymer segmental dynamics is investigated in a series of silica-filled rubbers. The presence of inert fillers in polymers greatly affects the mechanical and physical performance of the final materials. For example, silica has been proposed as a reinforcing agent of elastomers in tire production. Results from quasielastic neutron scattering and Dynamic Mechanical Thermal Analysis (DMTA) measurements are presented on styrene-ran-butadiene rubber filled with silica. A clear indication is obtained of the existence of a bimodal dynamics, which can be rationalized in terms of the relaxation of bulk rubber and the much slower relaxation of the rubber adsorbed on the filler surface.

  2. Saliva and dental erosion

    PubMed Central

    BUZALAF, Marília Afonso Rabelo; HANNAS, Angélicas Reis; KATO, Melissa Thiemi

    2012-01-01

    Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective This review discusses the role of salivary factors on the development of dental erosion. Material and Methods A search was undertaken on MEDLINE website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects. PMID:23138733

  3. Bisphenol A and Related Compounds in Dental Materials

    PubMed Central

    Fleisch, Abby F.; Sheffield, Perry E.; Chinn, Courtney; Edelstein, Burton L.; Landrigan, Philip J.

    2014-01-01

    CONTEXT Dental sealants and composite filling materials containing bisphenol A (BPA) derivatives are increasingly used in childhood dentistry. Evidence is accumulating that BPA and some BPA derivatives can pose health risks attributable to their endocrine-disrupting, estrogenic properties. OBJECTIVES To systematically compile and critically evaluate the literature characterizing BPA content of dental materials; to assess BPA exposures from dental materials and potential health risks; and to develop evidence-based guidance for reducing BPA exposures while promoting oral health. METHODS The extant toxicological literature and material safety data sheets were used as data sources. RESULTS BPA is released from dental resins through salivary enzymatic hydrolysis of BPA derivatives, and BPA is detectable in saliva for up to 3 hours after resin placement. The quantity and duration of systemic BPA absorption is not clear from the available data. Dental products containing the bisphenol A derivative glycidyl dimethacrylate (bis-GMA) are less likely to be hydrolyzed to BPA and have less estrogenicity than those containing bisphenol A dimethacrylate (bis-DMA). Most other BPA derivatives used in dental materials have not been evaluated for estrogenicity. BPA exposure can be reduced by cleaning and rinsing surfaces of sealants and composites immediately after placement. CONCLUSIONS On the basis of the proven benefits of resin-based dental materials and the brevity of BPA exposure, we recommend continued use with strict adherence to precautionary application techniques. Use of these materials should be minimized during pregnancy whenever possible. Manufacturers should be required to report complete information on the chemical composition of dental products and encouraged to develop materials with less estrogenic potential. PMID:20819896

  4. Chlorhexidine-releasing methacrylate dental composite materials.

    PubMed

    Leung, Danny; Spratt, David A; Pratten, Jonathan; Gulabivala, Kishor; Mordan, Nicola J; Young, Anne M

    2005-12-01

    Light curable antibacterial, dental composite restoration materials, consisting of 80 wt% of a strontium fluoroaluminosilicate glass dispersed in methacrylate monomers have been produced. The monomers contained 40-100 wt% of a 10 wt% chlorhexidine diacetate (CHXA) in hydroxyethylmethacrylate (HEMA) solution and 60-0 wt% of a 50/50 mix of urethane dimethacrylate (UDMA) and triethyleneglycol dimethacrylate (TEGDMA). On raising HEMA content, light cure polymerisation rates decreased. Conversely, water sorption induced swelling and rates of diffusion controlled CHXA release from the set materials increased. Experimental composites with 50 and 90 wt% of the CHXA in HEMA solution in the monomer were shown, within a constant depth film fermentor (CDFF), to have slower rates of biofilm growth on their surfaces between 1 and 7 days than the commercial dental composite Z250 or fluoride-releasing dental cements, Fuji II LC and Fuji IX. When an excavated bovine dentine cylinder re-filled with Z250 was placed for 10 weeks in the CDFF, both bacteria and polymers from the artificial saliva penetrated between the material and dentine. With the 50 wt% experimental HEMA/CHXA formulation, this bacterial microleakage was substantially reduced. Polymer leakage, however, still occurred. Both polymer and bacterial microleakage were prevented with a 90 wt% HEMA/CHXA restoration in the bovine dentine due to swelling compensation for polymerisation shrinkage in combination with antibacterial release.

  5. YouTube, dentistry, and dental education.

    PubMed

    Knösel, Michael; Jung, Klaus; Bleckmann, Annalen

    2011-12-01

    The objective of this study was to systematically assess the informational value, intention, source, and bias of videos related to dentistry available on the video-sharing Internet platform YouTube. YouTube (www.youtube.com) was searched for videos related to dentistry, using the system-generated sorts "by relevance" and "most viewed" and two categories (All and Education). Each of the first thirty results was rated by two assessors filling out a questionnaire for each (total: 120). The data were subjected to statistical analysis using Cohen's kappa, Pearson's correlation coefficient tau, Mann-Whitney U-tests, and a nonparametric three-way ANOVA, including an analysis of the interaction between the sorting and category effect, with an α-level of 5 percent. The scan produced 279,000 results in the category All and 5,050 in the category Education. The analysis revealed a wide variety of information about dentistry available on YouTube. The purpose of these videos includes entertainment, advertising, and education. The videos classified under Education have a higher degree of usefulness and informational value for laypersons, dental students, and dental professionals than those found in a broader search category. YouTube and similar social media websites offer new educational possibilities that are currently both underdeveloped and underestimated in terms of their potential value. Dentists and dental educators should also recognize the importance of these websites in shaping public opinion about their profession.

  6. Dental materials for cleft palate repair.

    PubMed

    Sharif, Faiza; Ur Rehman, Ihtesham; Muhammad, Nawshad; MacNeil, Sheila

    2016-04-01

    Numerous bone and soft tissue grafting techniques are followed to repair cleft of lip and palate (CLP) defects. In addition to the gold standard surgical interventions involving the use of autogenous grafts, various allogenic and xenogenic graft materials are available for bone regeneration. In an attempt to discover minimally invasive and cost effective treatments for cleft repair, an exceptional growth in synthetic biomedical graft materials have occurred. This study gives an overview of the use of dental materials to repair cleft of lip and palate (CLP). The eligibility criteria for this review were case studies, clinical trials and retrospective studies on the use of various types of dental materials in surgical repair of cleft palate defects. Any data available on the surgical interventions to repair alveolar or palatal cleft, with natural or synthetic graft materials was included in this review. Those datasets with long term clinical follow-up results were referred to as particularly relevant. The results provide encouraging evidence in favor of dental and other related biomedical materials to fill the gaps in clefts of lip and palate. The review presents the various bones and soft tissue replacement strategies currently used, tested or explored for the repair of cleft defects. There was little available data on the use of synthetic materials in cleft repair which was a limitation of this study. In conclusion although clinical trials on the use of synthetic materials are currently underway the uses of autologous implants are the preferred treatment methods to date.

  7. Clinical evaluation of glass ceramic inlays (Dicor).

    PubMed

    Stenberg, R; Matsson, L

    1993-04-01

    The purpose of the study was to evaluate the clinical behavior of ceramic class-II inlays (Dicor) in the first 2 years after placement. As a reference, a similar number of dental amalgam restorations were followed up during the same period. Twenty-five inlays and 25 dental amalgams were placed on premolars and first molars of 20 and 19 patients (15-19 years old), respectively. The inlay preparations were made in accordance with the manufacturer's recommendations, and the inlays were produced by a licensed Dicor laboratory. The inlays were luted, using a glass ionomer cement. The dental amalgam preparations were made using standard class-II preparation techniques and filled with ANA 2000. The inlays were evaluated after 6, 12, and 24 months, and the dental amalgam restorations after 24 months, using the criteria suggested by Ryge. In addition, the 24-month examination included proximal recording of dental plaque and gingivitis. With the exception of two inlays that fractured during the observation period, all ceramic inlays showed excellent ratings for anatomic form, marginal discoloration, and marginal caries at all examinations. Two inlays showed minor marginal defects but were classified within the range of acceptance with no need for replacement. The two fractured inlays were replacements of earlier fractured dental amalgams. The clinical behavior of the dental amalgam restorations was in most respects similar to that of the ceramic inlays. Unlike the inlays, however, no dental amalgams fractured during the observation period.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Root canal filling evaluation using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Negrutiu, Meda L.; Sinescu, Cosmin; Topala, Florin; Nica, Luminita; Ionita, Ciprian; Marcauteanu, Corina; Goguta, Luciana; Bradu, Adrian; Dobre, George; Rominu, Mihai; Podoleanu, Adrian Gh.

    2010-04-01

    Endodontic therapy consists in cleaning and shaping the root canal system, removing organic debris and sealing the intra-canal space with permanent filling materials. The purpose of this study was to evaluate various root canal fillings in order to detect material defects, the marginal adaptation at the root canal walls and to assess the quality of the apical sealing. 21 extracted single-root canal human teeth were selected for this study. We instrumented all roots using NiTi rotary instruments. All canals were enlarged with a 6% taper size 30 GT instrument, 0,5 mm from the anatomical apex. The root canals were irrigated with 5% sodium hypochlorite, followed by 17% ethylenediaminetetraacetic acid (EDTA). After the instrumentation was completed, the root canals were obturated using a thermoplasticizable polymer of polyesters. In order to assess the defects inside the filling material and the marginal fit to the root canal walls, the conebeam micro-computed tomography (CBμCT) was used first. After the CBμCT investigation, time domain optical coherence tomography working in en face mode (TDefOCT) was employed to evaluate the previous samples. The TDefOCT system was working at 1300 nm and was doubled by a confocal channel at 970 nm. The results obtained by CBμCT revealed no visible defects inside the root-canal fillings and at the interfaces with the root-canal walls. TDefOCT investigations permit to visualize a more complex stratificated structure at the interface filling material/dental hard tissue and in the apical region.

  9. 42 CFR Appendix G to Part 75 - Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Dental Assistants in Dental Radiography G Appendix G to Part 75 Public Health PUBLIC HEALTH SERVICE...—Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography The following section... individual State licensure processes, all of which include assessment of competence in dental radiography....

  10. 42 CFR Appendix G to Part 75 - Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Dental Assistants in Dental Radiography G Appendix G to Part 75 Public Health PUBLIC HEALTH SERVICE...—Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography The following section... individual State licensure processes, all of which include assessment of competence in dental radiography....

  11. 42 CFR Appendix G to Part 75 - Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Dental Assistants in Dental Radiography G Appendix G to Part 75 Public Health PUBLIC HEALTH SERVICE...—Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography The following section... individual State licensure processes, all of which include assessment of competence in dental radiography....

  12. 42 CFR Appendix G to Part 75 - Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Dental Assistants in Dental Radiography G Appendix G to Part 75 Public Health PUBLIC HEALTH SERVICE...—Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography The following section... individual State licensure processes, all of which include assessment of competence in dental radiography....

  13. Professional and personal enhancement: a pragmatic approach in dental education

    PubMed Central

    2016-01-01

    Purpose: Students of health education are often offended by the transitions and challenges they face while encountering diverse people, ideas and academic workloads. They may be offended because of reasons not only related to their societal background but also to their basic competence in managing transitions. In the Asian scenario, students enter the first year of professional education in their late teen age along with the definition of self which was created by their parents. There are different issues that arise in this age group that may positively shape or negatively affect the personalities of students. They need to achieve a sense of balance between personal and professional traits on their own. Several students are often unable to cultivate the expected required qualities, which leads to an abject state of mind and hinder their progress. We identified the most common personal and professional hurdles in the lives of dental students and we provided experiential solutions to overcome the hurdles by using a sociable approach through an integrated, continuing education program. Methods: Designing and implementing a cohesive, amalgamated and inspiring personal and professional enhancement action program for dental students. Results: Feedback from students reflected that the needs and expectations of students vary with academic phase. In addition students expressed that this program series inculcated some positive skills, and overall, they are satisfied with the utility of the program. Conclusion: Personal and professional enhancement of students in accordance with individual needs as well as with expected requirements needs a committed administrative action plan. Our results in this context are encouraging and can be considered for application in dental institutions. PMID:26932496

  14. Dental pain and associated factors among pregnant women: an observational study.

    PubMed

    Krüger, Marta S M; Lang, Celina A; Almeida, Luiza H S; Bello-Corrêa, Fernanda O; Romano, Ana R; Pappen, Fernanda G

    2015-03-01

    The present study aimed to determine the prevalence of dental pain during pregnancy and its association with sociodemographic factors and oral health conditions among 315 pregnant women in South Brazil. Participants were interviewed to obtain sociodemographic data, such as age, educational level, employment status, family income, and marital and parity status. Medical and dental histories were also collected, including the occurrence of dental pain and the use of dental services during pregnancy. Clinical examinations were performed to assess the presence of visible plaque and gingival bleeding and to calculate the decayed, missing, and filled teeth index. Means and standard deviations of continuous variables and frequencies and percentages of categorical variables were calculated. Independent variables were included in a multivariate logistic regression analysis. A total of 173 (54.9 %) pregnant women reported dental pain during pregnancy. After adjustment of the analysis, caries activity remained the main determinant of dental pain (odds ratio 3.33, 95 % CI 1.67-6.65). The prevalence of dental pain during pregnancy was high and the presence of caries activity was a determinant of dental pain. Moreover, access to oral health care was low, despite pregnant women's increased need for dental assistance.

  15. Evaluating the Relationship of Dental Fear with Dental Health Status and Awareness

    PubMed Central

    2016-01-01

    Introduction Dental fear is one of the most common problems in dentistry, for both the patient and for the dentist. This issue can have an important effect on an individual’s dental health. Aim The aim of this paper was to report on the prevalence of dental anxiety and to explore if high levels of anxiety are associated with sociodemographic factors, oral health status, and level of oral health awareness. Materials and Methods The sample for this cross-sectional study included 294 patients (154 males and 140 females). All participants filled out a Dental Fear Survey (DFS) to evaluate their level of dental fear. Gender, age, education level, socioeconomic status and oral health awareness were also noted. Oral health behaviors and oral health awareness levels were investigated using seven questions. Also, the periodontal status of all participants was evaluated using the Community Periodontal Index of Treatment Needs (CPITN). Differences between different subgroups were tested using the chi-square test. Results There was a statistically significant difference between the DFS groups with regard to sociodemographic data. Women had significantly higher scores than men, and young patients had significantly higher scores than others. Patients with low education levels and low socioeconomic status had high DFS scores. Periodontal status was better in groups that had scores in the low and moderate ranges compared to groups that had high scores on the DFS. There was a statistically significant difference between the groups of DFS and CPITN (p<0.05). Patients with low and moderate levels of DFS answered the oral health knowledge questions correctly. There was a statistically significant difference between the DFS groups based on correct answers to the oral health knowledge questions (p<0.05). Conclusion The elimination of dental fear is very important and should be treated according to a patient-centered assessment. These individuals were informed about the dental treatment

  16. Mercury contamination - Amalgamate (contract with NFS and ADA). Stabilize Elemental Mercury Wastes. Mixed Waste Focus Area. OST Reference Number 1675

    SciTech Connect

    None, None

    1999-09-01

    Through efforts led by the Mixed Waste Focus Area (MWFA) and its Mercury Working Group (HgWG), the inventory of bulk elemental mercury contaminated with radionuclides stored at various U. S. Department of Energy (DOE) sites is thought to be approximately 16 m3 (Conley et al. 1998). At least 19 different DOE sites have this type of mixed low-level waste in their storage facilities. The U. S. Environmental Protection Agency (EPA) specifies amalgamation as the treatment method for radioactively contaminated elemental mercury. Although the chemistry of amalgamation is well known, the practical engineering of a sizable amalgamation process has not been tested (Tyson 1993). To eliminate the existing DOE inventory in a reasonable timeframe, scaleable equipment is needed that can: produce waste forms that meet the EPA definition of amalgamation, produce waste forms that pass the EPA Toxicity Characteristic Leaching Procedure (TCLP) limit of 0.20 mg/L, limit mercury vapor concentrations during processing to below the Occupational Safety and Health Administration’s (OSHA) 8-hour worker exposure limit (50 mg/m3) for mercury, and perform the above economically.

  17. Three-year clinical evaluation of cuspal coverage with combined composite-amalgam in endodontically-treated maxillary premolars.

    PubMed

    Shafiei, Fereshteh; Memarpour, Mahtab; Doozandeh, Maryam

    2010-01-01

    This clinical study evaluated the clinical performance of cuspal coverage with combined composite-amalgam restorations in endodontically-treated maxillary premolars over a three-year period. Thirty-six maxillary premolars, each with a Class II cavity in 36 patients ranging in age between 28 and 52 years, were selected after endodontic treatment. After reduction of the buccal and palatal cusps, internal coverage and veneering of the reduced buccal cusp was performed with composite. The remaining cavity and reduced palatal cusp were restored with high-copper amalgam. The restorations were evaluated at baseline and in one-, two- and three-year recalls with USPHS criteria. Changes in characteristics of the restorations were analyzed with the Cochran Q-test at a significance level of p < 0.05. Most of the restorations received an overall score of alpha, except two restorations, which showed a slight discrepancy at the composite-amalgam interface after one year (p > 0.05). Four restorations exhibited slight discoloration of the composite veneering after three years (p < 0.05). No restoration exhibited fracture after three years. It was concluded that combined composite-amalgam cusp coverage of endodontically-treated maxillary premolars showed acceptable clinical performance after three years.

  18. Fracture resistance of cuspal coverage of endodontically treated maxillary premolars with combined composite-amalgam compared to other techniques.

    PubMed

    Shafiei, F; Memarpour, M; Karimi, F

    2011-01-01

    This in vitro study investigated the fracture resistance of teeth restored with combined composite-amalgam for cuspal coverage compared to direct coverage with composite (with or without an amalgam base) and composite onlay. Seventy-two intact maxillary premolars were randomly divided into six groups (n=12). The two control groups were G1, intact teeth (negative control), and G2, mesio-occlusodistal preparation only (positive control). Each of the four experimental groups used a different type of restoration for the prepared teeth: G3, direct composite cusp coverage; G4, composite onlay; G5, direct composite coverage with an amalgam base; and G6, combined composite-amalgam cuspal coverage. After thermocycling, fracture strength was tested. The data were analyzed with analysis of variance and the least significant differences post hoc tests (α=0.05). Mean fracture resistance in the six groups (in N) were G1, 1101 ±1 86; G2, 228 ± 38; G2, 699 ± 161; G4, 953 ± 185; G5, 859 ± 146; and G6, 772 ± 154. There were significant differences between G1 and all the other groups except for G4 and between G2 and all the other groups. Fracture strength in G3 also differed significantly compared to G4 and G5. The difference between G4 and G6 was statistically significant (p<0.05), but the difference between G3 and G6 was not (p>0.05).

  19. Can-Filled Crash Barrier

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1983-01-01

    Crash barrier composed largely of used aluminum beverage cans protects occupants of cars in collisions with poles or trees. Lightweight, can-filled barrier very effective in softening impact of an automobile in head-on and off-angle collisions. Preliminary results indicate barrier is effective in collisions up to 40 mi/h (64 km/h).

  20. Filling in the retinal image

    NASA Technical Reports Server (NTRS)

    Larimer, James; Piantanida, Thomas

    1990-01-01

    The optics of the eye form an image on a surface at the back of the eyeball called the retina. The retina contains the photoreceptors that sample the image and convert it into a neural signal. The spacing of the photoreceptors in the retina is not uniform and varies with retinal locus. The central retinal field, called the macula, is densely packed with photoreceptors. The packing density falls off rapidly as a function of retinal eccentricity with respect to the macular region and there are regions in which there are no photoreceptors at all. The retinal regions without photoreceptors are called blind spots or scotomas. The neural transformations which convert retinal image signals into percepts fills in the gaps and regularizes the inhomogeneities of the retinal photoreceptor sampling mosaic. The filling-in mechamism plays an important role in understanding visual performance. The filling-in mechanism is not well understood. A systematic collaborative research program at the Ames Research Center and SRI in Menlo Park, California, was designed to explore this mechanism. It was shown that the perceived fields which are in fact different from the image on the retina due to filling-in, control some aspects of performance and not others. Researchers have linked these mechanisms to putative mechanisms of color coding and color constancy.

  1. Space-filling polyhedral sorbents

    DOEpatents

    Haaland, Peter

    2016-06-21

    Solid sorbents, systems, and methods for pumping, storage, and purification of gases are disclosed. They derive from the dynamics of porous and free convection for specific gas/sorbent combinations and use space filling polyhedral microliths with facial aplanarities to produce sorbent arrays with interpenetrating interstitial manifolds of voids.

  2. Unsteady Capillary Filling By Electrocapillarity

    NASA Astrophysics Data System (ADS)

    Kang, In Seok; Lee, Jung A.

    2016-11-01

    Unsteady filling of electrolyte solution inside a nanochannel by the electrocapillarity effect is studied. The filling rate is predicted as a function of the bulk concentration of the electrolyte, the surface potential (or surface charge density), and the cross sectional shape of the channel. Since the driving force of the flow is the electrocapillarity, it is first analyzed by using the solution of the Poisson-Boltzmann equation. From the analysis, it is found that the results for many different cross sectional shapes can be unified with good accuracy if the hydraulic radius is adopted as the characteristic length scale of the problem. Especially in the case of constant surface potential, for both limits of κh -> 0 and κh -> ∞ , it can be shown theoretically that the electrocapillarity is independent of the cross sectional shape if the hydraulic radius is the same. In order to analyze the geometric effects more systematically, we consider the regular N-polygons with the same hydraulic radius and the rectangles of different aspect ratios. Washburn's approach is then adopted to predict the filling rate of electrolyte solution inside a nanaochannel. It is found that the average filling velocity decreases as N increases in the case of regular N-polygons with the same hydraulic radius. This is because of that the regular N-polygons of the same hydraulic radius share the same inscribing circle. This work has been supported by BK21+ program.

  3. [Psychometric assessment of the German version of the Index of Dental Anxiety and Fear (IDAF-4C+) - a new instrument for measuring dental anxiety].

    PubMed

    Tönnies, Sven; Mehrstedt, Mats; Fritzsche, Anja

    2014-03-01

    JM Armfield introduced the questionnaire "Index of Dental Anxiety and Fear" with the intention of giving research into this complex area a broader theoretical base. A German translation of the IDAF-4C+ was given to 287 dental patients in Germany, of which 188 were recruited from a Dental Fears Clinic. Together with the IDAF-4C+ the patients also filled out the Dental Anxiety Scale, the Dental Fear Survey and Beck's Anxiety Inventory. The good reliability of the IDAF core dental anxiety and fear module, that was found in the original Australian research, was found to be even better in the translated version. The factorial validity of the fear- and phobia module could be confirmed, the stimulus module only partly. With the translation of the IDAF-4C+ there is for the first time a questionnaire available in the German language that not only measures the extent of the dental fears but also diagnoses the anxiety-causing stimuli and intends to differentiate between dental fear and phobia.

  4. Brood amalgamation in the Bristle-thighed Curlew Numenius tahitiensis: process and function

    USGS Publications Warehouse

    Lanctot, Richard B.; Gill, R.E.; Tibbitts, T.L.; Handel, C.M.

    1995-01-01

    Alloparental care in birds generally involves nonbreeding adults that help at nests or breeding adults that help raise young in communal nests. A less often reported form involves the amalgamation of broods, where one or more adults care for young that are not their own. We observed this phenomenon among Bristle-thighed Curlew Numenius tahitiensis broods in western Alaska during 1990–1992. Amalgamation of broods generally involved the formation of temporary and extended associations. Temporary associations were formed by the incidental convergence of broods soon after they left their nests. During this period, parents defended distinct brood-rearing areas, were antagonistic to conspecifics and remained together for less than 3 days. Extended associations formed when chicks were 1–2 weeks old. Here, parents and their broods occupied distinct, but adjacent, brood-rearing areas and moved around as a unit. Whether a brood participated in either temporary or extended associations or remained solitary appeared to depend on brood density in the immediate area and on hatching date. When chicks were 3–4 weeks old, aggregations of up to ten broods formed wherein young mixed and parents defended a common brood-rearing area. All broods (n = 48) that survived to fledging joined such aggregations. Alloparental care involved only antipredator defence and was not associated with activities such as feeding and brooding. Most female parents abandoned their broods shortly after the young could fly and when aggregations were forming. The female parent of a pair always deserted its young before or on the same day as the male parent and, in every aggregation, one or two males continued to tend young for about 5 days longer than other male parents. In most cases, adults deserted the young 2–6 days before the young departed the area when about 38 days old. Bristle-thighed Curlews also formed temporary associations with American and Pacific Golden Plover Pluvialis dominica and

  5. History of dental hygiene research.

    PubMed

    Bowen, Denise M

    2013-01-01

    Dental hygiene is defined as the science and practice of the recognition, treatment and prevention of oral diseases. The history of dental hygiene research is considered in the context of the development of the discipline and an emerging infrastructure. Research-related events supporting the growth and maturation of the profession are considered from the early years to the most recent. The benefits of preventive oral health services provided by dental hygienists have been supported by research, and the practice of dental hygiene has expanded as a result of research findings since its inception 100 years ago. Dental hygienists' engagement in research, however, did not begin until the 1960s as research associates or administrators, primarily with dental researchers as primary investigators. The Journal of Dental Hygiene (JDH) has provided information for dental hygiene practice since 1927, and has been the primary venue for dissemination of dental hygiene research since 1945. Graduate education in dental hygiene at the master's degree level and the work of early dental hygiene researchers led to the first conference on dental hygiene research in 1982. Over 30 years later, dental hygiene has established a meta-paradigm and defined conceptual models, built an initial infrastructure to support research endeavors and contributed much to the development of dental hygiene as a unique discipline. A doctoral degree in the discipline, continued theory-based research, initiatives to foster collaborations between dental hygiene and other researchers and enhanced capabilities to attract funding to support large scale studies are goals that must be attained through the efforts of future researchers to address the needs for additional development in the discipline of dental hygiene. Dental hygiene research supports the growing discipline and its value to society.

  6. Prevalence of dental caries among 12–14 year old children in Qatar

    PubMed Central

    Al-Darwish, Mohammed; El Ansari, Walid; Bener, Abdulbari

    2014-01-01

    Background To ensure the oral health of a population, clinicians must deliver appropriate dental services, and local communities need to have access to dental care facilities. However, establishment of this infrastructure must be based on reliable information regarding disease prevalence and severity in the target population. Objectives The aims of this study were to measure the incidence of dental caries in school children aged 12–14 throughout Qatar, including the influence of socio-demographic factors. Materials and methods A cross-sectional study was conducted in Qatar from October 2011 to March 2012. A total of 2113 children aged 12–14 were randomly selected from 16 schools located in different geographic areas. Three calibrated examiners using World Health Organization (WHO) criteria to diagnose dental caries performed the clinical examinations. Data analyses were subsequently conducted. Results The mean decayed, missing, and filled teeth index values were respectively 4.62 (±3.2), 4.79 (±3.5), and 5.5 (±3.7), for 12, 13, and 14 year-old subjects. Caries prevalence was 85%. The mandibular incisors and canines were least affected by dental caries, while maxillary and mandibular molars exhibited the highest incidence of dental caries. Dental caries were affected by socio-demographic factors; significant differences were detected between female and male children, where more female children showed dental caries than male children. In addition, children residing in semi-urban areas showed more dental caries than in urban areas. Conclusion Results indicated that dental caries prevalence among school children in Qatar has reached critical levels, and is influenced by socio-demographic factors. The mean decayed, missing, and filled teeth values obtained in this study were the second highest detected in the Eastern Mediterranean region. PMID:25057232

  7. Epidemiology of dental caries in children in the United Arab Emirates.

    PubMed

    Al-Bluwi, Ghada S M

    2014-08-01

    Dental caries has a significant impact on the general health and development of children. Understanding caries epidemiology is an essential task for the United Arab Emirates (UAE) policymakers to evaluate preventive programmes and to improve oral health. The purpose of this review is to collect and summarise all data available in the published literature on the epidemiology of dental caries in the UAE in children aged under 13 years. This will provide dental health planners with a comprehensive data summary, which will help in the planning for and evaluation of dental caries prevention programmes. Data were collected from the various published studies in PubMed, Academic Search Complete, Google, and the reference lists in relevant articles. Four keywords were used in the search: 'dental caries,' 'epidemiology,' 'prevalence,' and 'UAE'. All studies conducted in the UAE in general or any single emirate that sheds light on the prevalence of dental caries of children under 13 years were included in this literature review. Studies on early childhood caries and factors associated with dental caries were also included. The review comprises 11 published surveys of childhood caries in UAE. The earliest study was published in 1991 and the most recent was published in 2011. The range of decayed, missing and filled primary teeth (dmft) in UAE children (age between 4 years and 6 years) was 5.1-8.4. For the 12-year-old group the decayed missing and filled permanent teeth (DMFT) ranged from 1.6 to 3.24. Baseline data on oral health and a good understanding of dental caries determinants are necessary for setting appropriate goals and planning for preventive oral health programmes. The current data available on the dmft and DMFT indicate that childhood dental caries is still a serious dental public health problem in the UAE that warrants immediate attention by the government and policy makers.

  8. 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.

  9. AunHgm Clusters: Mercury Aurides, Gold Amalgams, or van der Waals Aggregates?

    NASA Astrophysics Data System (ADS)

    Zaleski-Ejgierd, Patryk; Pyykkö, Pekka

    2009-02-01

    The class of bimetallic clusters, AunMm (M = Zn, Cd, Hg), is calculated at the ab initio level using the DFT, RI-MP2, and CCSD(T) methods. For the triatomic Au2M (M = Zn, Cd), the auride-type linear Au-M-Au structures are preferred; for Au2Hg, the linear Au-Au-Hg "amalgam" is preferred. The mixed cation [HgAuHg]+, an analog of the known solid-state species Hg32+, is predicted. For larger AunHgm clusters, the results are similar to the isoelectronic AunM- anions. Several local minima and transition states are identified. All are found to be planar.

  10. A Mediterranean-style model for early Neoproterozoic amalgamation of South China

    NASA Astrophysics Data System (ADS)

    Zhang, Kai-Jun

    2017-04-01

    A Mediterranean-style model is proposed for early Neoproterozoic amalgamation of South China, based on recognition of the Guangxi promontory on the southeastern margin of the Yangtze craton through a synthesis of geologic, geophysical and chronological data. The model suggests that, while the Guangxi promontory collided with the overriding Cathaysia terrane along the Yunkai orogeny during the earliest Neoproterozoic, the convergence between the Yangtze craton and the Cathaysia terrane paused or slowed down, which triggered the upper Rhine Graben-style Kangdian impact rift along the western Yangtze margin and resulted in roll-back of the oceanic slab trapped in the embayments and sequential formation of backarc rifts in the Cathaysia margin during the early Neoproterozoic. This model predicts a complex diachronous Yangtze-Cathaysia collision history, first at the Guangxi promontory at ∼1000 Ma and finally at the Guizhou reentrant at ∼830 Ma.

  11. Design, synthesis, characterization and anti-inflammatory evaluation of novel pyrazole amalgamated flavones.

    PubMed

    Chavan, Hemant V; Bandgar, Babasaheb P; Adsul, Laxman K; Dhakane, Valmik D; Bhale, Pravin S; Thakare, Vishnu N; Masand, Vijay

    2013-03-01

    A series of novel pyrazole amalgamated flavones has been designed and synthesized from 1-methyl-5-(2,4,6-trimethoxy-phenyl)-1H-pyrazole 6. The structures of regioisomers 6 and 7 were resolved by 2D (1)H-(1)H COSY, (1)H-(13)C HSQC and (1)H-(13)C HMBC experiments. The newly synthesized compounds were tested for their in vitro COX inhibition and in vivo carrageenan induced hind paw edema in rats and acetic acid induced vascular permeability in mice. Although the compounds have inhibitory profile against both COX-1 and COX-2, some of the compounds are found to be selective against COX-2, supported by inhibition of paw edema and vascular permeability. Docking studies were also carried out to determine the structural features which sway the anti-inflammatory activity of the tested compounds. The keto and phenolic -OH are major factors that are prominently involved in interaction with COX-2 active site.

  12. Dental Implantology in U.S. Dental Schools.

    ERIC Educational Resources Information Center

    Bavitz, J. Bruce

    1990-01-01

    The results of a survey of 44 dental schools corroborate the belief that dental implantology is gaining widespread acceptance in U.S. dental schools. Currently, predoctoral students have limited clinical participation. Most programs have taken the position that clinical techniques are best taught within the existing specialties at a graduate…

  13. Bulimia and Anorexia Nervosa in Dental and Dental Hygiene Curricula.

    ERIC Educational Resources Information Center

    Gross, Karen B. W.; And Others

    1990-01-01

    Dentists and dental hygienists are in a unique position to identify an eating disorder patient from observed oral manifestations and to refer the patient for psychological therapy. The inclusion of information on general and oral complications of bulimia and anorexia nervosa in dental and dental hygiene curriculum was examined. (MLW)

  14. A qualitative study of limited access permit dental hygienists in Oregon.

    PubMed

    Battrell, Ann M; Gadbury-Amyot, Cynthia C; Overman, Pamela R

    2008-03-01

    Many states have adopted alternative oral health care delivery systems that include expanded roles for dental hygienists. This qualitative study was designed to evaluate the impact of the Limited Access Permit (LAP) legislation in Oregon and to understand the relationship between dental hygienists and dentists within this delivery system. The snowball sampling technique was used to identify LAP dental hygienists and collaborating dentists. The snowball sampling technique begins with the identification of a known expert in the field who serves as the initial "sampling unit." Subsequent individuals are then recommended, or nominated, to the investigator by the initial study participant and are selected based upon the need to fill in or extend information. The final sample consisted of seven LAP dental hygienists and two collaborating dentists. Interviews, field observations, and document analysis were utilized for data collection. Factors that led to the creation of LAP dental hygiene practice, current LAP practice, personal characteristics, relationships between LAP dental hygienists and dentists, and the impact that LAP dental hygienists have had on access to oral health care were explored. Data revealed that the Oregon legislature twice expanded the LAP scope of practice to increase access to oral health care services. LAP dental hygienists practice in community and school-based settings. Common characteristics of LAP dental hygienists include entrepreneurship, lifelong learning, and a commitment to underserved populations. The findings from this study indicate that LAP dental hygienists and collaborating dentists have positive relationships. No evidence of lower quality of care in unsupervised dental hygiene practices was found. However, the impact of the LAP legislation is still unknown due to the limited numbers of LAP dental hygienists and the early nature of the LAP practice.

  15. On dental wear, dental work, and oral health in the type specimen (LB1) of Homo floresiensis.

    PubMed

    Jungers, William L; Kaifu, Yousuke

    2011-06-01

    The claim that the lower left first mandibular molar of LB1, the type specimen of Homo floresiensis, displays endodontic work, and a filling is assessed by digital radiography and micro-CT scanning. The M(1) tooth crown is heavily worn and exhibits extensive dentine exposure that is stained white, but there is no trace of endodontic treatment or a dental filling in this Indonesian fossil dated to 17.1-19.0 kya. Dental calculus (commonly observed in foragers) is present on the teeth of LB1, but there are no observable caries. The pattern of dental attrition in the mandibles of both LB1/2 and LB6/1 (moderate to extensive flat wear across the entire arch) is consistent with that seen in Plio-Pleistocene Homo fossils and in modern hunter-gatherers, and is not typical of most agriculturalists. We conclude that the dental-work and farming hypotheses are falsified and therefore irrelevant to the debate over the taxonomy and phylogeny of H. floresiensis.

  16. The effectiveness of four-cavity treatment systems in sealing amalgam restorations.

    PubMed

    Morrow, Leean A; Wilson, Nairn H F

    2002-01-01

    Amalgam does not bond to tooth tissue; therefore, restorations using such material are prone to leakage despite the deposition of corrosion products. This study evaluated the effectiveness of four cavity treatment systems placed in vivo in sealing restorations of amalgam. Four cavity treatment systems were investigated in this study: Cervitec, Gluma One Bond, Panavia 21 and Copaliner Dentin Varnish and Sealant. No cavity treatment was placed in an additional group to serve as a control. The teeth were extracted within 15 minutes of restoration placement. The specimens were thermocycled (5-55 +/- 2 degrees C, 500 cycles), immersed in a dye solution, sectioned and scored for leakage. Scanning electron microscopy also examined features of the tooth/restoration interfaces. There were statistically significant differences among the groups regarding leakage scores (p = 0.00). None of the materials tested consistently prevented leakage; however, use of Copaliner Dentin Varnish and Sealant resulted in less overall, occlusal and cervical microleakage than any other systems tested. Significantly more leakage was observed in relation to the cervical portions of the cavities (p = 0.00). No significant differences were identified between the leakage scores obtained for the buccal and palatal (lingual) cavities and the different tooth types (p = 0.52 and 0.83, respectively). A level of significance of 0.05 was selected in all cases. The benefits of the materials tested in this study need to be evaluated using robust, long-term clinical studies. Further work should continue to develop laboratory tests that predict the behavior and performance of cavity sealants in clinical service.

  17. Panoramic Dental X-Ray

    MedlinePlus

    ... Physician Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a ... Your e-mail address: Personal message (optional): Bees: Wax: Notice: RadiologyInfo respects your privacy. Information entered here ...

  18. The Primary Dental Care Workforce.

    ERIC Educational Resources Information Center

    Neenan, M. Elaine; And Others

    1993-01-01

    A study describes the characteristics of the current primary dental care workforce (dentists, hygienists, assistants), its distribution, and its delivery system in private and public sectors. Graduate dental school enrollments, trends in patient visits, employment patterns, state dental activities, and workforce issues related to health care…

  19. Dental ethics and emotional intelligence.

    PubMed

    Rosenblum, Alvin B; Wolf, Steve

    2014-01-01

    Dental ethics is often taught, viewed, and conducted as an intell enterprise, uninformed by other noncognitive factors. Emotional intelligence (EQ) is defined distinguished from the cognitive intelligence measured by Intelligence Quotient (IQ). This essay recommends more inclusion of emotional, noncognitive input to the ethical decision process in dental education and dental practice.

  20. Dental therapists: a global perspective.

    PubMed

    Nash, David A; Friedman, Jay W; Kardos, Thomas B; Kardos, Rosemary L; Schwarz, Eli; Satur, Julie; Berg, Darren G; Nasruddin, Jaafar; Mumghamba, Elifuraha G; Davenport, Elizabeth S; Nagel, Ron

    2008-04-01

    In 1921, New Zealand began training school dental nurses, subsequently deploying them throughout the country in school-based clinics providing basic dental care for children. The concept of training dental nurses, later to be designated dental therapists, was adopted by other countries as a means of improving access to care, particularly for children. This paper profiles six countries that utilise dental therapists, with a description of the training that therapists receive in these countries, and the context in which they practice. Based on available demographic information, it also updates the number of dental therapists practising globally, as well as the countries in which they practice. In several countries, dental therapy is now being integrated with dental hygiene in training and practice to create a new type of professional complementary to a dentist. Increasingly, dental therapists are permitted to treat adults as well as children. The paper also describes the status of a current initiative to introduce dental therapy to the United States. It concludes by suggesting that dental therapists can become valued members of the dental team throughout the world, helping to improve access to care and reducing existing disparities in oral health.