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1

Molarity  

NSDL National Science Digital Library

What determines the concentration of a solution? Learn about the relationships between moles, liters, and molarity by adjusting the amount of solute and solution volume. Change solutes to compare different chemical compounds in water.

Simulations, Phet I.; Chamberlain, Julia; Malley, Chris; Lancaster, Kelly; Parson, Robert; Perkins, Kathy

2012-02-20

2

Molar Uprighting  

MedlinePLUS

... molar uprighting are the same as with any orthodontic procedure. There may be some discomfort. Also, the ... These can happen more often in people with orthodontic appliances, especially if they don't brush and ...

3

Molarization of Mandibular Second Premolar  

PubMed Central

ABSTRACT Macrodontia (megadontia, megalodontia, mac rodontism) is a rare shape anomaly that has been used to describe dental gigantism. Mandibular second premolars show an elevated variability of crown morphology, as are its eruptive potential and final position in the dental arch. To date, only eight cases of isolated macrodontia of second premolars have been reported in the literature. This case report presents clinical and radiographic findings of unusual and rare case of isolated unilateral molarization of left mandibular second premolar. How to cite this article: Mangla N, Khinda VIS, Kallar S, Brar GS. Molarization of Mandibular Second Premolar. Int J Clin Pediatr Dent 2014;7(2):137-139. PMID:25356014

Singh Khinda, Vineet Inder; Kallar, Shiminder; Singh Brar, Gurlal

2014-01-01

4

How Neanderthal molar teeth grew  

Microsoft Academic Search

Growth and development are both fundamental components of demographic structure and life history strategy. Together with information about developmental timing they ultimately contribute to a better understanding of Neanderthal extinction. Primate molar tooth development tracks the pace of life history evolution most closely, and tooth histology reveals a record of birth as well as the timing of crown and root

Roberto Macchiarelli; Luca Bondioli; André Debénath; Arnaud Mazurier; Jean-François Tournepiche; Wendy Birch; M. Christopher Dean

2006-01-01

5

The formation and evolution of Hule and Río Cuarto maars, Costa Rica  

NASA Astrophysics Data System (ADS)

The Hule and Río Cuarto maars are respectively located 11 and 18 km northward of the active crater of Poás volcano, on the Caribbean side of the Central Volcanic Range of Costa Rica. They lie on the northern part of Poás volcano massif, along a N-S trending, ~ 27 km-long volcanic fracture crossing the Poás volcano. The volcanic products from Hule maar (2.3 km × 1.8 km, area ~ 3.5 km 2) are mainly pyroclastic surges (poorly vesiculated andesites with very small plagioclases), silica-rich andesitic pumice flows, air-fall deposits, ballistic blocks, and reworked deposits that overlie the regional Pleistocene volcanic basement. They were produced during three main explosive phases. Two overlapping pyroclastic cones have developed within the Hule maar, and at least three lava fields are related to them (high-Al basalt to basaltic andesite). Another maar, Pata de Gallo (400 m across), is located less than 1 km off the SE rim of Hule. Río Cuarto is a nearly circular maar (700-850 m across) with a surface area of 0.33 km 2. Río Cuarto products include surges, ballistics and air-fall tephra, produced during three main explosive phases. These deposits show a narrow fan oriented westward, according to westerly wind direction. They indicate a westerly-directed surge (first 2 km), followed by air-fall deposits (up to 5 km away). Radiocarbon dating has shown that Hule was formed ~ 6.2 ka ago and Pata de Gallo probably formed ~ 2.8 ka ago, while the intra-maar products could have ages of ~ 1.7 ka or ~ 0.7 ka, indicating that Hule is a polygenetic maar. There are no radiocarbon ages yet for dating the formation of Río Cuarto maar, but archaeological data suggest that it erupted between 3-4 ka ago. The volume of pyroclastic deposits associated to Hule maar is estimated to be 0.51-0.53 km 3, from which ~ 20% is juvenile material, therefore 0.07-0.08 km 3 of new dense rock equivalent (DRE) magma, after subtracting 20-30% of porosity. The tephra from Río Cuarto is estimated to be 4.4 × 10 7 m 3, of which 0.008 m 3 correspond to DRE magma. The Hule and Río Cuarto maars are occupied by lakes and, in the last decades, several lake-overturn events have taken place, with a repeat cycle of six to seven years. The main outcome of these events has been the mass death of fish accompanied by changes in the lake color. In these systems, the hazard related to the possible occurrence of Nyos-type gas eruptions can be considered negligible or very local, but significant for tourists who camp by the lakes.

Alvarado, Guillermo E.; Soto, Gerardo J.; Salani, Flavia M.; Ruiz, Pablo; de Mendoza, Luis Hurtado

2011-04-01

6

40 CFR Table 1 to Subpart Ja of... - Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents  

Code of Federal Regulations, 2014 CFR

...false Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents 1 ...Part 60—Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents Constituent...F and 1 atmosphere. b MHC = molar heat content (higher heating value...

2014-07-01

7

40 CFR Table 1 to Subpart Ja of... - Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents  

Code of Federal Regulations, 2013 CFR

...false Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents 1 ...Part 60—Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents Constituent...F and 1 atmosphere. b MHC = molar heat content (higher heating value...

2013-07-01

8

Mesial force from unerupted third molars  

Microsoft Academic Search

TOP Erupting mandibular third molars are implicated as a cause of anterior crowding of mandibular teeth. The goal of this two-part investigation was to measure the mesial force exerted by unerupted mandibular third molars. We hypothesized that such a force increases the tightness of all proximal posterior tooth contacts mesial to the mandibular second molar, and that surgical removal of

Thomas E. Southard; Karin A. Southard; Larry W. Weeda

1991-01-01

9

Grazing Impacts Upon Earth's Surface: Towards an Understanding of the Rio Cuarto Crater Field  

NASA Astrophysics Data System (ADS)

The origin of the Rio Cuarto crater field, Argentina has been widely debated since the early 1990s when it was first brought to public attention. In a binary on-off sense, however, the craters are either of a terrestrial origin or they formed via a large asteroid impact. While there are distinct arguments in favour of the former option being the correct interpretation, it is the latter possibility that is principally investigated here, and five distinct impact formation models are described. Of the impact scenarios it is found that the most workable model, although based upon a set of fine-tuned initial conditions, is that in which a large, 100-150-m initial diameter asteroid, entered Earth's atmosphere on a shallow angle path that resulted in temporary capture. In this specific situation a multiple-thousand kilometer long flight path enables the asteroid to survive atmospheric passage, without suffering significant fragmentation, and to impact the ground as a largely coherent mass. Although the odds against such an impact occurring are extremely small, the crater field may nonetheless be interpreted as having potentially formed via a very low-angle, smaller than 5° to the horizon, impact with a ground contact speed of order 5 km/s. Under this scenario, as originally suggested by Schultz and Lianza (Nature 355:234, 1992), the largest of the craters (crater A) in the Rio Cuarto structure was produced in the initial ground impact, and the additional, smaller craters are interpreted as being formed through the down-range transport of decapitated impactor material and crater A ejecta.

Beech, Martin

2014-08-01

10

[Hyperthyroidism induced by molar pregnancy].  

PubMed

A case is reported of a Senegalese patient admitted for hydatiform mole. The serum human chorionic gonadotrophin concentration (hCG) was 900,000 UI.l-1. The patient was recognized to be clinically hyperthyroid with raised T4 and T3 values, but a very low TSH concentration. After two days of beta adrenergic blockade and carbimazole, a suction curettage was performed under general anaesthesia. Propranolol was again administered 6 hours after the surgery. Thyroid function returned to normal level two weeks after removal of the mole, suggesting that hCG was responsible for the thyrotoxicosis. Serum hCG concentrations closely paralleled those of free thyroxine, but the correlation was difficult to assess because of carbimazole. Clinical thyrotoxicosis is rare in molar pregnancy. The diagnosis being made in semi-urgent conditions, this raises the question of how to obtain rapid stabilization of the disease before surgery. PMID:8273931

Laurent, V; Besson, L; Doussin, J F; Rondelet, B; Banssillon, V

1993-01-01

11

Results of intentional replantation of molars  

Microsoft Academic Search

Purpose: This study evaluated the treatment outcome of intentional replantation of molars.Patients and Methods: Twenty-nine patients were treated with intentional replantation because conventional apicoectomy was not possible. The success rate was judged by clinical and radiographic parameters.Results: One molar (3%) had to be removed because of pain and mobility 4 weeks postsurgery, and three molars (11%) had to be removed

Gerry M Raghoebar; Arjan Vissink

1999-01-01

12

Molar Malocclusions in Pine Voles (Microtus pinetorum)  

PubMed Central

Here we describe 5 cases of molar malocclusions in adult pine voles (Microtus pinetorum) used for behavioral endocrinology studies. This species belongs to the subfamily Microtinae, which possess aradicular hypsodont molars. The abnormal molars identified caused apparent difficulty in mastication, resulting in poor body condition necessitating euthanasia. Postmortem examination of the oral cavity revealed grossly elongated mandibular and maxillary molars with abnormal wear at occlusal surfaces. This colony health problem was addressed successfully by adding autoclaved hardwood sticks to each cage as an enrichment tool. PMID:19653952

Harvey, Stephen B; Alworth, Leanne C; Blas-Machado, Uriel

2009-01-01

13

Antibiotics in third molar surgery.  

PubMed

The aim of this survey was to assess the knowledge and practice of Swiss dentists focusing on the use of antibiotics in prophylactic surgical removal of lower wisdom teeth. A postal survey was conducted among all 3288 dentists who are members of the Swiss Dental Society (SSO) representing nearly all dentists in Switzerland. The questionnaire consisted of 13 questions with mostly multiple-choice answers. Demographic profile, surgical experience, the use of antibiotics, and wound management, i.e. wound closure and the use of mouth rinse were assessed. A response rate of 55% was obtained. Most Swiss dentists perform surgical extractions in their practices. Of all dentists, 18.6% used antibiotics routinely, but a large variation was found comparing the three linguistic regions of Switzerland with the highest prescription rate of 48% in the French-speaking south-west of Switzerland. Fifty-two percent of dentists prescribed amoxicillin in a dose of 750 mg. Most often three daily doses were prescribed (47%). A postoperative regime was prescribed by 54.4% of dentists. French language (p=0.003), graduation from the university of Geneva (p=0.007), foreign diplomas (p<0.001), and dentists with diplomas awarded from 2001-2006 (p=0.004) showed a highly significant correlation with the use of antibiotics. In Switzerland, prophylactic antibiotics are used in third molar surgery. Antibiotic prescription however largely depends on geographical situation and dentist profiles. The assessment of antibiotic use in private practices is important in the light of growing evidence that antibiotic overuse may lead to development of multiresistant bacterial strains. In a second part results regarding wound management and mouth rinse will be presented. PMID:24671748

Vlcek, Daniel; Razavi, Amir; Kuttenberger, Johannes J

2014-01-01

14

Role of third molars in orthodontics  

PubMed Central

The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not been discussed at the same level is their involvement in orthodontic therapy. The aim of this study is to present a review of the contemporary literature regarding the most broadly discussed aspects of the multifactorial role of third molars in orthodontics and which are of general dental interest too. PMID:25685759

Almpani, Konstantinia; Kolokitha, Olga-Elpis

2015-01-01

15

Role of third molars in orthodontics.  

PubMed

The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not been discussed at the same level is their involvement in orthodontic therapy. The aim of this study is to present a review of the contemporary literature regarding the most broadly discussed aspects of the multifactorial role of third molars in orthodontics and which are of general dental interest too. PMID:25685759

Almpani, Konstantinia; Kolokitha, Olga-Elpis

2015-02-16

16

Fabrication and Evaluation of a Noncompliant Molar Distalizing Appliance: Bonded Molar Distalizer  

PubMed Central

Objective Attempts to treat class II malocclusions without extraction in non-compliant patients have led to utilization of intraoral molar distalizing appliances. The purpose of this study was to investigate dental and skeletal effects of Bonded Molar Distalizer (BMD) which is a simple molar distalizing appliance. Materials and Methods Sixteen patients (12 girls, four boys) with bilateral half-cusp class II molar relationship, erupted permanent second molars and normal or vertical growth pattern were selected for bilateral distalization of maxillary molars via BMD. The screws were activated every other day, alternately. Lateral cephalograms and study models were obtained before treatment and after 11 weeks activation of the appliance. Results Significant amounts of molar distalization, molar distal tipping and anchorage loss were observed. The mean maxillary first molar distal movement was 1.22±0.936 mm with a distal tipping of 2.97±3.74 degrees in 11 weeks. The rate of distal movement was 0.48 mm per month. Reciprocal mesial movement of the first premolars was 2.26±1.12 mm with a mesial tipping of 4.25±3.12 degrees. Maxillary incisors moved 3.55±1.46 mm and tipped 9.87±5.03 degrees mesially. Lower anterior face height (LAFH) decreased 1.28±1.36 mm. Conclusion BMD is appropriate for distalizing maxillary molars, especially in patients with critical LAFH, although significant amounts of anchorage loss occur using this appliance. PMID:22457837

Sodagar, A.; Ahmad Akhoundi, M. S.; Rafighii, A.; Arab, S.

2011-01-01

17

Third molars: a threat to periodontal health??  

PubMed

The third molars have received the fair amount of interest in literature. It has been blamed for problems such as-lower incisor crowding, atypical facial pain, caries etc. They are considered as 'waste bins' in dental practices as they are regarded as functionally non-essential. While making the clinical decision, they are given less importance and often extraction is considered to be the treatment option. Despite periodontal problems that can arise with extracted third molars, retention of third molars can also lead to periodontal problems with the adjacent teeth in addition to teeth farther to third molars. Of late, it is very important to consider the periodontal problems while making the clinical decision. This review paper has been discussed keeping this as prime objective. PMID:23730073

Kaveri, G S; Prakash, Shobha

2012-06-01

18

Lingual exposure during mandibular third molar surgery.  

PubMed

The necessity for surgical exposure of the lingual aspect of mandibular third molars will vary according to the severity of the impaction and the surgical technique adopted. A retractor is described for use in those cases when major lingual retraction is required. The retractor provides optimum access to the mandibular third molar area with adequate protection for the lingual nerve, tongue retraction and enhanced illumination by light reflection. It can be used under both local and general anaesthesia. PMID:415017

Stacy, G C

1977-12-01

19

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage  

Microsoft Academic Search

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG

Gero S. M Kinzinger; Ulrike B Fritz; Franz-Günter Sander; Peter R Diedrich

2004-01-01

20

The mesioangular third molar--to extract or not to extract? Analysis of 776 consecutive third molars.  

PubMed

Introduction Distal caries in lower second molars has been associated with mesioangular third molars. Caries detection and restoration can be difficult. If caries progresses, root canal treatment or extraction of the second molar can be necessary.Aims To identify the prevalence of caries in lower third molars and the distal aspect of corresponding lower second molars in patients referred for lower third molar assessment.Methods Analysis of OPG X-rays for 420 consecutive patients (776 third molars) referred to three maxillofacial centres over a five month period.Results Thirty-four percent of third molars were mesioangular. There was radiographic evidence of distal second molar caries in 42% of these. When unerupted mesioangular third molars were excluded this increased to 54%. There was no difference in age or dental health of these patients compared to the whole group. There was no angulation of the mesioangular third molar for which distal caries in the second molar was more likely.Conclusion Distal caries in lower second molars related to a mesioangular third molar is a common finding in oral and maxillofacial patients in secondary care, especially if the third molar is fully or partially erupted. If such a third molar is left in situ, close monitoring and regular bitewing radiographs are recommended. PMID:19498427

Allen, R T; Witherow, H; Collyer, J; Roper-Hall, R; Nazir, M A; Mathew, G

2009-06-13

21

Uncertainty assessment of Si molar mass measurements  

NASA Astrophysics Data System (ADS)

The uncertainty of the Si molar mass measurement is theoretically investigated by means of a two-isotope model, with particular emphasis to the role of this measurement in the determination of the Avogadro constant. This model allows an explicit calibration formula to be given and propagation of error analysis to be made. It also shows that calibration cannot correct for non-linearity.

Mana, G.; Massa, E.; Valkiers, S.; Willenberg, G.-D.

2010-01-01

22

Molar and molecular views of choice  

Microsoft Academic Search

The molar and molecular views of behavior are not different theories or levels of analysis; they are different paradigms. The molecular paradigm views behavior as composed of discrete units (responses) occurring at moments in time and strung together in chains to make up complex performances. The discrete pieces are held together as a result of association by contiguity. The molecular

William M Baum

2004-01-01

23

Geosphere-Biosphere Interactions in Bio-Activity Volcanic Lakes: Evidences from Hule and Rìo Cuarto (Costa Rica)  

PubMed Central

Hule and Río Cuarto are maar lakes located 11 and 18 km N of Poás volcano along a 27 km long fracture zone, in the Central Volcanic Range of Costa Rica. Both lakes are characterized by a stable thermic and chemical stratification and recently they were affected by fish killing events likely related to the uprising of deep anoxic waters to the surface caused by rollover phenomena. The vertical profiles of temperature, pH, redox potential, chemical and isotopic compositions of water and dissolved gases, as well as prokaryotic diversity estimated by DNA fingerprinting and massive 16S rRNA pyrosequencing along the water column of the two lakes, have highlighted that different bio-geochemical processes occur in these meromictic lakes. Although the two lakes host different bacterial and archaeal phylogenetic groups, water and gas chemistry in both lakes is controlled by the same prokaryotic functions, especially regarding the CO2-CH4 cycle. Addition of hydrothermal CO2 through the bottom of the lakes plays a fundamental priming role in developing a stable water stratification and fuelling anoxic bacterial and archaeal populations. Methanogens and methane oxidizers as well as autotrophic and heterotrophic aerobic bacteria responsible of organic carbon recycling resulted to be stratified with depth and strictly related to the chemical-physical conditions and availability of free oxygen, affecting both the CO2 and CH4 chemical concentrations and their isotopic compositions along the water column. Hule and Río Cuarto lakes were demonstrated to contain a CO2 (CH4, N2)-rich gas reservoir mainly controlled by the interactions occurring between geosphere and biosphere. Thus, we introduced the term of bio-activity volcanic lakes to distinguish these lakes, which have analogues worldwide (e.g. Kivu: D.R.C.-Rwanda; Albano, Monticchio and Averno: Italy; Pavin: France) from volcanic lakes only characterized by geogenic CO2 reservoir such as Nyos and Monoun (Cameroon). PMID:25058537

Cabassi, Jacopo; Tassi, Franco; Mapelli, Francesca; Borin, Sara; Calabrese, Sergio; Rouwet, Dmitri; Chiodini, Giovanni; Marasco, Ramona; Chouaia, Bessem; Avino, Rosario; Vaselli, Orlando; Pecoraino, Giovannella; Capecchiacci, Francesco; Bicocchi, Gabriele; Caliro, Stefano; Ramirez, Carlos; Mora-Amador, Raul

2014-01-01

24

Geosphere-biosphere interactions in bio-activity volcanic lakes: evidences from Hule and Rìo Cuarto (Costa Rica).  

PubMed

Hule and Río Cuarto are maar lakes located 11 and 18 km N of Poás volcano along a 27 km long fracture zone, in the Central Volcanic Range of Costa Rica. Both lakes are characterized by a stable thermic and chemical stratification and recently they were affected by fish killing events likely related to the uprising of deep anoxic waters to the surface caused by rollover phenomena. The vertical profiles of temperature, pH, redox potential, chemical and isotopic compositions of water and dissolved gases, as well as prokaryotic diversity estimated by DNA fingerprinting and massive 16S rRNA pyrosequencing along the water column of the two lakes, have highlighted that different bio-geochemical processes occur in these meromictic lakes. Although the two lakes host different bacterial and archaeal phylogenetic groups, water and gas chemistry in both lakes is controlled by the same prokaryotic functions, especially regarding the CO2-CH4 cycle. Addition of hydrothermal CO2 through the bottom of the lakes plays a fundamental priming role in developing a stable water stratification and fuelling anoxic bacterial and archaeal populations. Methanogens and methane oxidizers as well as autotrophic and heterotrophic aerobic bacteria responsible of organic carbon recycling resulted to be stratified with depth and strictly related to the chemical-physical conditions and availability of free oxygen, affecting both the CO2 and CH4 chemical concentrations and their isotopic compositions along the water column. Hule and Río Cuarto lakes were demonstrated to contain a CO2 (CH4, N2)-rich gas reservoir mainly controlled by the interactions occurring between geosphere and biosphere. Thus, we introduced the term of bio-activity volcanic lakes to distinguish these lakes, which have analogues worldwide (e.g. Kivu: D.R.C.-Rwanda; Albano, Monticchio and Averno: Italy; Pavin: France) from volcanic lakes only characterized by geogenic CO2 reservoir such as Nyos and Monoun (Cameroon). PMID:25058537

Cabassi, Jacopo; Tassi, Franco; Mapelli, Francesca; Borin, Sara; Calabrese, Sergio; Rouwet, Dmitri; Chiodini, Giovanni; Marasco, Ramona; Chouaia, Bessem; Avino, Rosario; Vaselli, Orlando; Pecoraino, Giovannella; Capecchiacci, Francesco; Bicocchi, Gabriele; Caliro, Stefano; Ramirez, Carlos; Mora-Amador, Raul

2014-01-01

25

Positional changes of the third molar in orthodontically treated patients  

PubMed Central

Objective and Rationale. Over the years, the effects of the third molars eruption on the dental arches have been studied extensively. Still, literature provides less data regarding the effects of the orthodontic treatment on the third molars position. The aim of our study was to assess the positional changes of the third molars relative to the occlusal plane and to the second molar long axis, changes occurred during orthodontic treatment performed with or without premolar extractions. Method. This study included 20 orthodontic treated patients: 10 of them with premolar extractions and 10 without premolar extractions. The pretreatment and post treatment panoramic radiographs were analyzed, and the angles between the third molar long axis and the occlusal plane and between the long axis of the third molar and the long axis of the second molar were measured. Results. Changes in third molar position, from pretreatment to post treatment, for the two groups of patients were evaluated by using the Student’s t-test. The results of the statistical analysis revealed an improvement in third molars position, the best results were seen in the lower third molars, in the group of patients treated with premolar extractions. PMID:23904878

Mihai, AM; Lulache, IR; Grigore, R; Sanabil, AS; Boiangiu, S; Ionescu, E

2013-01-01

26

Diagnostic Value of Lectins in Differentiation of Molar Placentas  

PubMed Central

Objective(s) Distinction of hydatidiform moles from non-molar specimens and subclassification of hydatidiform moles as complete and partial are important for clinical practice, but diagnosis based solely on histomorphology suffers from poor interobserver reproducibility. Nowadays, pathologists rely on molecular techniques, however these methods are technically difficult, relatively expensive, and time consuming, and cannot be applied in all laboratories. Therefore, a relatively easy, time- and cost-effective ancillary tool, would be helpful. This study aimed to assess the role of lectins in differential diagnosis of molar placentas. Materials and Methods Lectin histochemistry with a panel of HRP-conjugated lectins comprising SBA, DBA, MPA, PNA, VVA, UEA-1, LTA, GS-? (B4), and WGA were performed in 20 non-molar (hydropic and non-hydropic spontaneous abortions) and 20 molar (partial and complete moles), formalin-fixed paraffin-embedded tissue samples. On the basis of staining intensity, sections were graded and Kruskal-Wallis non-parametric statistical test was used to compare differences between samples. Results There was a significant difference between the reactivities of LTA and UEA-? with syncytiotrophoblasts of molar and non-molar specimens (P<0.001). These lectins generally showed a moderate reactivity with syncytiotrophoblasts of molar group but did not react with this cell population in non-molar group. Furthermore, WGA showed relatively increased reaction with syncytiotrophoblasts of molar tissues compared with abortions, however, this did not reach to statistical significance (P=0.07). No major differences were seen in other lectins reactivities between the studied groups. Conclusion The present study showed that UEA-1 and LTA lectins may be used as cytochemical probes in differentiating molar from non-molar placentas, but did not differentiate partial moles from complete moles. PMID:23653842

Atabaki Pasdar, Fatemeh; Khooei, Alireza; Fazel, Alireza; Mahmoudi, Mahmoud; Nikravesh, Mohammad Reza; Khaje Delui, Mohammad

2012-01-01

27

Complications after apicoectomy in maxillary premolar and molar teeth  

Microsoft Academic Search

This study was designed to enumerate the number of perforations to the maxillary sinus while performing apicoectomy on maxillary premolar and molar teeth and to evaluate possible complications as a result of these perforations. A total of 472 apicoectomies were performed in 440 patients; perforations occurred in 10.4% of teeth, 23% in molars, 13% in second premolars and 2% in

Alan Freedman; Isack Horowitz

1999-01-01

28

RESEARCH Open Access Half-molar sodium lactate infusion improves  

E-print Network

RESEARCH Open Access Half-molar sodium lactate infusion improves cardiac performance in acute heart for the myocardium at rest and during stress. We tested the effects of half-molar sodium lactate infusion on cardiac by 1 ml/kg/h continuous infusion for 24 hours. The control group received only a 3 ml/kg bolus

Paris-Sud XI, Université de

29

Finite element analysis of mandibular molar protraction mechanics using miniscrews.  

PubMed

Summary BACKGROUND/OBJECTIVES: The aim of this study was to determine the most desirable force system to achieve molar protraction from an interdental miniscrew minimizing side-effects. Several iterations of force delivery were simulated through variations in the height of a miniscrew, length of a molar extension arm, and incorporation of a lingual force. PMID:25005109

Nihara, Jun; Gielo-Perczak, Krystyna; Cardinal, Lucas; Saito, Isao; Nanda, Ravindra; Uribe, Flavio

2014-07-01

30

Impaction of Permanent Mandibular Second Molars in Ethnic Chinese Schoolchildren  

Microsoft Academic Search

Objective: ?To investigate the prevalence of impaction of permanent mandibular second molars and associated dental and radiographic characteristics of Chinese children in Hong Kong. MaterialsandMethods: ?Dental and radiographic records of a group of Chinese school- children were studied retrospectively. Cases of impaction of 1 or both permanent man- dibular second molars were selected. Demographic data and dental and radiographic findings

Shiu-yin Cho; Yung Ki; Vanessa Chu; Joseph Chan

31

Prosthetic rehabilitation of a hemisected maxillary molar: a rare entity.  

PubMed

Gingival recession beyond grade III and grade IV level involving furcation defects can lead to tooth loss if not intervened at appropriate time. The treatment options include scaling and root planing, Furcation-plasty, Tunnel preparation, Root separation and resection. The chief complaint of the patient was pain in the upper left first molar because of grade III furcation involvement. Since it was a four rooted molar, the treatment of choice was hemisection of the tooth and extraction of the distal half following endodontic treatment. As the second molar was mesially tilted the prosthodontic rehabilitation was done with a hybrid prosthesis involving a full coverage conventional porcelain fused to metal retainer on the hemisected molar and a resin bonded partial coverage retainer on the tilted second molar. The resultant prosthesis is termed as "Hybrid prosthesis". PMID:24431763

Yadav, Preeti; Tahir, Mohammed; Kumar, M V Sunil; Rao, Harikesh

2013-09-01

32

Presence of third molars in orthodontic patients from northern Greece  

PubMed Central

Objective The purpose of the present study was to investigate the frequency of presence of third molar teeth and their distribution in each jaw and each side, according to sex, in a group of orthodontic patients with permanent dentition from northern Greece. Methods The sample included panoramic radiographs from 220 patients with permanent dentition (mean age 13.62 ± 1.81). The ?2 test was used to assess the relationships between the variables, and the Fisher’s exact test was used in cases where the expected frequencies in each cell were <5. Results The frequency of third molar presence was 79.1%, and 20.9% was the frequency of third molar agenesis. Intersexual differences in the number of third molars was not statistically significant. There was a correlation between the distribution of third molars on the right and the left side (Fisher’s exact test = 100.788; P = 0). The two sides showed the same tendency toward the presence or absence of third molars. A correlation was also found between the distribution of maxillary and mandibular third molars (Fisher’s exact test = 24.372; P = 0). In each jaw, the presence or absence of third molars was highly related to the number of third molars found in the other jaw. Conclusion The present results showed that in this orthodontic group of northern Greek patients, presence accounted for 79.1% and agenesis for 20.9%. No significant difference was found between the frequencies of third molar presence on the left and right sides in either the maxilla or mandible. PMID:22701086

Barka, Georgia; Tretiakov, Georgios; Theodosiou, Theodosios; Ioannidou-Marathiotou, Ioulia

2012-01-01

33

Excess molar volumes and excess molar enthalpies of quinoline + aromatic hydrocarbons at 303. 15 K  

SciTech Connect

Excess molar volumes V[sub m][sup E] and excess molar enthalpies H[sub m][sup E][sub m] for quinoline + benzene, toluene, o-xylene, or p-xylene for the whole range of compositions have been measured at 303.15 K. The values of H[sub m][sup E] and V[sub m][sup E] for these mixtures suggest that quinoline is partly self-associated and there is strong interaction (weak hydrogen bonding) between quinoline and aromatic hydrocarbons. The values of V[sub m][sup E] and H[sub m][sup E] have also been computed from the Flory and Abe theory and Sanchez and Lacombe theory as well as from the Graph theory. All the theories correctly predict the sign or magnitude of H[sub m][sup E]. Only the Graph theory is able to predict correctly the sign or magnitude of V[sub m][sup E]; the other theories give a poor estimate of V[sub m][sup E].

Kalra, K.C.; Singh, K.C.; Spah, D.C.; Batra, R.; Maken, S. (Maharshi Dayanand Univ., Rohtak (India). Dept. of Chemistry)

1993-01-01

34

Molar heat capacity and entropy of calcium metal  

USGS Publications Warehouse

The heat capacity of calcium has been measured at 85 mean temperatures between T ??? 8 K and T ??? 369 K using an adiabatically-shielded calorimeter in an intermittent heating mode. At T = 298.15 K, the recommended values for the molar heat capacity, molar entropy, and molar enthalpy increment referred to T = 0 are (25.77 ?? 0.08) J??K-1??mol-1, (42.90 ?? 0.11) J??K-1??mol-1, and (5811 ?? 12) J??mol-1, respectively. The uncertainties are twice the standard deviation of the mean. ?? 1997 Academic Press Limited.

Hemingway, B.S.; Robie, R.A.; Chase, M.W.

1997-01-01

35

Revascularization/Regeneration performed in immature molars: case reports.  

PubMed

These 3 case reports the outcome of revascularization treatment in necrotic immature molars. During treatment, a tri antibiotic mix was used to disinfect the pulp for 2 weeks. Then a blood clot was created in the canal, over which mineral trioxide aggregate was placed. After 24 months, the immature molars showed continuation of root development. The patients were asymptomatic, no sinus tracts were evident and apical periodontitis was resolved Results from these cases show that revascularization/regeneration using 3Mix-MP method could be effective for managing immature permanent molar teeth with pulpal necrosis. PMID:23855165

Sönmez, I S; Akbay Oba, A; Erkmen Almaz, M

2013-01-01

36

Orthodontic space closure after first molar extraction without skeletal anchorage  

Microsoft Academic Search

Objective  The aim of the study was an analysis of effects and side-effects during mesialization of second molars after extraction of\\u000a the first permanent molars using the anterior dentition\\/premolars (PM) as an anchorage unit.\\u000a \\u000a \\u000a \\u000a \\u000a Patients and methods  A total of 35 patients were examined retrospectively who had undergone unilateral or bilateral first permanent molar extraction\\u000a in the upper or lower arch due

Collin Jacobs; Claudia Jacobs-Müller; Carolin Luley; Christina Erbe; Heiner Wehrbein

2011-01-01

37

Functional Patterns of Molar Occlusion in Platyrrhine Primates  

E-print Network

mechanics . Dentition Molars . Occlusion Tooth wear Platyrrhine. ABSTRACT Mechanico-functional features the particular kinds of insects fed upon by the different genera and the de- tailed characters of the dentition

Rosenberger, Alfred H.

38

Fragility and molar volumes of non-stoichiometric chalcogenides  

E-print Network

accurately using the age old Archimedes' principle that was enunciated about 250 BC in Syracuse, Italyreprint #12;Fragility and molar volumes of non-stoichiometric chalcogenides: The crucial role chalcogenides, fragility, glass, modulated differential scanning calorimetry, rigidity, stress * Corresponding

Boolchand, Punit

39

Nuclear relaxation in bcc 3 He for large molar volumes  

Microsoft Academic Search

We report the results of measurements of longitudinal and transverse nuclear relaxation timesT1 andT2 in bcc3He at 300 mK and at a Larmor frequency of 3 MHz for molar volumes 22.6?V?24.9 cm3. It is found, even in this extended range of molar volumes, that the relaxation times increase withV as\\u000a

M. Devoret; A. S. Greenberg; D. Estève; N. S. Sullivan; M. Chapellier

1982-01-01

40

Finite Element Reconstruction of a Mandibular First Molar  

PubMed Central

Introduction Mandibular first molar is the most important tooth with complicated morphology. In finite element (FE) studies, investigators usually prefer to model anterior teeth with a simple and single straight root; it makes the results deviate from the actual case. The most complicated and time-consuming step in FE studies is modeling of the desired tooth, thus this study was performed to establish a finite element method (FEM) of reconstructing a mandibular first molar with the greatest precision. Materials and Methods An extracted mandibular first molar was digitized, and then radiographed from different aspects to achieve its outer and inner morphology. The solid model of tooth and root canals were constructed according to this data as well as the anatomy of mandibular first molar described in the literature. Result A three-dimensional model of mandibular first molar was created, giving special consideration to shape and root canal system dimensions. Conclusion This model may constitute a basis for investigating the effect of different clinical situations on mandibular first molars in vitro, especially on its root canal system. The method described here seems feasible and reasonably precise foundation for investigations. PMID:23717327

Ehsani, Sara; Mirhashemi, Fatemeh Sadat; Asgary, Saeed

2013-01-01

41

Bonded molar tubes: a retrospective evaluation of clinical performance.  

PubMed

This study investigated time to first failure of stainless steel orthodontic first permanent molar tubes (Ormco Corp) bonded with a light-cured resin adhesive (Transbond) and assessed whether this was related to patient gender, age of the patient at the start of treatment, the presenting malocclusion, or the operator. All first molar tubes were bonded to intact buccal enamel, free of any restoration. Survival analysis was carried out on data from 483 patients with 1190 bonded first molar tubes. For each case, a single molar tube, either that which was first to fail or had the shortest follow-up time, was chosen for analysis. The median time until first bonded tube failure was 699 days with an overall failure rate of 21% recorded. There was no significant difference in time to first failure of molar tubes with respect to patient gender or presenting malocclusion but significant differences were recorded with respect to the patients' age at the start of treatment and the operator. Age at the start of treatment and operator were identified as independently useful predictors of bonded molar tube survival. PMID:10358250

Millett, D T; Hallgren, A; Fornell, A C; Robertson, M

1999-06-01

42

Genetic integration of molar cusp size variation in baboons  

PubMed Central

Many studies of primate diversity and evolution rely on dental morphology for insight into diet, behavior, and phylogenetic relationships. Consequently, variation in molar cusp size has increasingly become a phenotype of interest. In 2007 we published a quantitative genetic analysis of mandibular molar cusp size variation in baboons. Those results provided more questions than answers, as the pattern of genetic integration did not fit predictions from odontogenesis. To follow up, we expanded our study to include data from the maxillary molar cusps. Here we report on these later analyses, as well as inter-arch comparisons with the mandibular data. We analyzed variation in two-dimensional maxillary molar cusp size using data collected from a captive pedigreed breeding colony of baboons, Papio hamadryas, housed at the Southwest National Primate Research Center. These analyses show that variation in maxillary molar cusp size is heritable and sexually dimorphic. We also estimated additive genetic correlations between cusps on the same crown, homologous cusps along the tooth row, and maxillary and mandibular cusps. The pattern for maxillary molars yields genetic correlations of one between the paracone-metacone and protocone-hypocone. Bivariate analyses of cuspal homologues on adjacent teeth yield correlations that are high or not significantly different from one. Between dental arcades, the non-occluding cusps consistently yield high genetic correlations, especially the metaconid-paracone and metaconid-metacone. This pattern of genetic correlation does not immediately accord with the pattern of development and/or calcification, however these results do follow predictions that can be made from the evolutionary history of the tribosphenic molar. PMID:20034010

Koh, Christina; Bates, Elizabeth; Broughton, Elizabeth; Do, Nicholas T.; Fletcher, Zachary; Mahaney, Michael C.; Hlusko, Leslea J.

2010-01-01

43

Mandibular first molar with six root canals: a rare entity.  

PubMed

Recently, there has been an ongoing trend of case reports that highlight the presence of more than four root canals in mandibular first molars. This tendency warns clinicians to be more prudent when dealing with mandibular first molars requiring endodontic treatment. Moreover, radiographic examination should be taken as a clue providing tool rather than as an absolute guide to anatomy and its associated aberrances. This case reports the successful non-surgical endodontic management of a mandibular first molar with six root canal systems with three canals in the mesial root and three in the distal root. The classification of root canal systems found in this case was Sert and Bayirli type XV in both the roots. After non-surgical endodontic treatment, the tooth was restored definitively with a resin composite core followed by porcelain fused to the metal crown. This case adds to the library of previously reported cases of mandibular first molars with six root canals and further emphasises on the importance of rare morphological deviations that may occur in the mandibular first molars. PMID:25082869

Hasan, Muhammad; Rahman, Munawar; Saad, Najeeb

2014-01-01

44

Western Saudi adolescent age estimation utilising third molar development  

PubMed Central

Objective: The aim of this study was to establish reference data on third molar morphology/development for age estimation in Western Saudi adolescents, between ages 14 and 23 years of old. Materials and Methods: The orthopantomograms of 130 individuals (males and females), were examined, and the stage of third molar development were evaluated. Results: Mean ages, standard deviations, and percentile distributions are presented for each stage of development. The mean estimated age for all participants (n = 130) was 219.7 months, and this differed significantly (P < 0.05) from the mean chronological age (226.5 months). Deviations of predicted age from real age showed 28.5% of all participants had their age estimated within 1 year (±12 months) of their chronological age. Most (43%) had their age underestimated by more than 12 months and the remaining 28.5% had their age overestimated by more than 12 months of their chronological age. Differences in left-right symmetry information of third molars were detected and were higher in the maxilla (92%) than in the mandible (82%). For all molars reaching stage “H” most individuals (males and females) were over the age 18 years of old. Males reach the developmental stages earlier than females. Conclusion: Third molar tooth development can be reliably used to generate mean age and the estimated age range for an individual of unknown chronological age. Further studies with large populations are needed for better statistical results. PMID:25202206

Alshihri, Amin M.; Kruger, Estie; Tennant, Marc

2014-01-01

45

A 3-dimensional analysis of molar movement during headgear treatment.  

PubMed

Superimposition of serial cephalograms provides a limited description of tooth movement that could be complemented by data obtained from serial dental casts. The aim of this study was to develop a mathematical method for superimposing 3-dimensional data obtained from selected landmarks on longitudinally collected dental casts to describe maxillary first molar movement during headgear treatment. The material consisted of dental casts taken bimonthly from 36 children whose Class II Division 1 malocclusion was treated with straight-pull headgear during a 24-month period. Control data were collected from initial and final models of 38 subjects with a similar malocclusion who were not treated during a 24-month observation period. Spatial data from each subject's initial model were oriented similarly in an anatomically derived coordinate system, and a best-fit superimposition of palatal rugae landmarks from subsequent models allowed the measurement of molar movement. On average, headgear treatment resulted in distal movement of the molars, and the fitted net difference between treated and control subjects was 3.00 mm (SE, 0.37 mm; P < .001). Also, the headgear caused significantly more molar extrusion (0.56 mm; SE, 0.20 mm; P < .006) and buccal expansion (0.58 mm; SE, 0.17 mm; P < .001) on average than in the control group. Poor reliability of the method for measuring molar rotations indicated that they could not be determined accurately. Longitudinal description of molar movement for each subject revealed great individual variability in the amount and pattern of tooth movement. Several reasons could account for the wide range of individual variation and warrant exploration. PMID:11786867

Ashmore, Jennifer L; Kurland, Brenda F; King, Gregory J; Wheeler, Timothy T; Ghafari, Joseph; Ramsay, Douglas S

2002-01-01

46

Endodontic Management of a Maxillary Molar with Three Mesiobuccal Canals  

PubMed Central

It is imperative that the clinician should have comprehensive knowledge about the normal anatomy and its variations of the teeth as the deviations from the usual are very common. An increased awareness of unusual anatomy and a better understanding of the root canal system guide the clinician in accurate diagnosis and treatment of such variations in order to achieve a successful endodontic outcome. The maxillary first molar has been shown to have a wide variation in respect to the number of canals specifically noted in the mesiobuccal root. The current case report shows the successful management of a maxillary molar in which the mesiobuccal root had three canals. PMID:25505997

Gundam, Sirisha; Maddu, Radhika; Gurram, Sindhura Reddy

2014-01-01

47

Treatment of Ectopic Mandibular Second Permanent Molar with Elastic Separators  

PubMed Central

Ectopic eruption is a developmental disturbance in which the tooth fails to follow its normal eruption pathway. Ectopic eruption of the second molar is relatively rare. This paper presents the case of thirteen-year-old male with an ectopic mandibular second permanent molar. The condition was corrected with surgical exposure and placement of elastic separators. This case report lays emphasis on the practice of basic methods to obtain acceptable results rather than extensive surgical or orthodontic corrections. It is advised that ectopic teeth should not be neglected especially when it concerns developing caries and malocclusion. PMID:25050182

Rajesh, R.; Naveen, V.; Amit, S.; Baroudi, Kusai; Sampath Reddy, C.; Namineni, Srinivas

2014-01-01

48

Surveillance without chemotherapy in a woman with recurrent molar pregnancy  

PubMed Central

A 27-year-old fouth gravida patient with previous two partial molar pregnancies and one missed abortion underwent a suction evacuation for partial molar pregnancy at 9?weeks of gestation. She was followed up with serum HCG values. Though the HCG level reduced from a pre-evacuation value of 1?40?223–31?157?mIU/ml 1?week post procedure, the levels continued to be positive in low titres 6?months after suction evacuation. The management options were discussed with the patient and a decision was taken to continue surveillance with serial HCG titres. HCG levels normalised after 11?months without the need for chemotherapy. PMID:23429019

Bagga, Rashmi; Siwatch, Sujata; Srinivasan, Radhika; Dhaliwal, Lakhbir Kaur

2013-01-01

49

Correlations between elastic moduli and molar volume in metallic glasses  

NASA Astrophysics Data System (ADS)

We report clear correlations between bulk modulus (K) and average molar volume Vm, and between Poisson's ratio ? and Vm for various bulk metallic glasses. The origin for the correlations between elastic moduli and Vm are discussed. The established correlation, associated with Poisson's ratio ?, and since the ? correlates with plasticity of metallic glasses, indicates that the average molar volume is important factor to be considered for plastic metallic glasses searching. The found correlations also suggest a close relation between the mechanical properties and the short-range atomic bonding, and assist in understanding deformation behavior in metallic glasses.

Wang, J. Q.; Wang, W. H.; Yu, H. B.; Bai, H. Y.

2009-03-01

50

Correlations between elastic moduli and molar volume in metallic glasses  

SciTech Connect

We report clear correlations between bulk modulus (K) and average molar volume V{sub m}, and between Poisson's ratio {nu} and V{sub m} for various bulk metallic glasses. The origin for the correlations between elastic moduli and V{sub m} are discussed. The established correlation, associated with Poisson's ratio {nu}, and since the {nu} correlates with plasticity of metallic glasses, indicates that the average molar volume is important factor to be considered for plastic metallic glasses searching. The found correlations also suggest a close relation between the mechanical properties and the short-range atomic bonding, and assist in understanding deformation behavior in metallic glasses.

Wang, J. Q.; Wang, W. H.; Yu, H. B.; Bai, H. Y. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2009-03-23

51

Procedures to recover DNA from pre-molar and molar teeth of decomposed cadavers with different post-mortem intervals.  

PubMed

A task-force to resolve 26 pending forensic caseworks was carried out. We tested four different protocols to extract DNA from molar and pre-molar teeth from 26 cadavers with post-mortem intervals from 2 months to 12 years. We compared the amount of DNA and DNA profiles with the time elapsed between death and laboratory procedures. Molar or pre-molar teeth were removed from the corpses, cleaned, and DNA was extracted using 2 or 12h of incubation on lysis buffer and filtered using concentration column or precipitated with isopropanol. DNA profiles were obtained using PowerPlex16™ System PCR Amplification Kit, AmpFlSTR(®) Yfiler™ and/or mtDNA sequencing. Complete DNA profiles comparison and statistical evaluation allowed unambiguous identification of the 26 victims. No significant differences were observed in the amount of DNA obtained with the distinct incubation times. The use of concentration column resulted in an increased amount of DNA when compared to isopropanol. However, the lower concentration of DNA obtained with isopropanol seemed to have been compensated by the higher purity. No significant differences in the number of amplified loci were found. A non-significant tendency was found between the amount of total DNA recovered and the time elapsed between death and laboratory procedures. The increase of post-mortem time did not interfere in the analysed autosomal loci. In conclusion, molar and pre-molar teeth were shown to be good candidates to obtain satisfactory DNA profiles, suggesting the high potential of tooth samples as source for DNA typing independently of the decomposed corpse's time or laboratory procedures. PMID:23040740

Raimann, Paulo E; Picanço, Juliane B; Silva, Deborah S B S; Albuquerque, Trícia C K; Paludo, Francis Jackson O; Alho, Clarice S

2012-11-01

52

Management of Six Root Canals in Mandibular First Molar  

PubMed Central

Success in root canal treatment is achieved after thorough cleaning, shaping, and obturation of the root canal system. This clinical case describes conventional root canal treatment of an unusual mandibular first molar with six root canals. The prognosis for endodontic treatment in teeth with abnormal morphology is unfavorable if the clinician fails to recognize extra root canals.

Gomes, Fabio de Almeida; Sousa, Bruno Carvalho

2015-01-01

53

Solutions : WtPercentToMolarity (4 Variations)  

NSDL National Science Digital Library

A common concentration unit used commercially is percent weight per volume (%W/V) which is the number of grams of solute in 100 mL of solution. A bottle of vinegar contains 5 %W/V acetic acid (CH 3 COOH). What is the molar concentration of acetic acid in the vinegar?

54

DNA Templated Synthesis (DTS) -Nature's effective molarity based approach-  

E-print Network

Translation DNA RNA Protein Replication mRNA tRNA Nucleic acid templated synthesis plays a important roleDNA Templated Synthesis (DTS) -Nature's effective molarity based approach- Organic Seminar 27th May of many reactants in one solution macromolecule- templated synthesis selective product formation one

Katsumoto, Shingo

55

Variations in the mechanical properties of Alouatta palliata molar enamel.  

PubMed

Teeth have provided insights into many topics including primate diet, paleobiology, and evolution, due to the fact that they are largely composed of inorganic materials and may remain intact long after an animal is deceased. Previous studies have reported that the mechanical properties, chemistry, and microstructure of human enamel vary with location. This study uses nanoindentation to map out the mechanical properties of Alouatta palliata molar enamel on an axial cross-section of an unworn permanent third molar, a worn permanent first molar, and a worn deciduous first molar. Variations were then correlated with changes in microstructure and chemistry using scanning electron microscopy and electron microprobe techniques. The hardness and Young's modulus varied with location throughout the cross-sections from the occlusal surface to the dentin-enamel junction (DEJ), from the buccal to lingual sides, and also from one tooth to another. These changes in mechanical properties correlated with changes in the organic content of the tooth, which was shown to increase from approximately 6% near the occlusal surface to approximately 20% just before the DEJ. Compared to human enamel, the Alouatta enamel showed similar microstructures, chemical constituents, and magnitudes of mechanical properties, but showed less variation in hardness and Young's modulus, despite the very different diet of this species. PMID:19672851

Darnell, Laura A; Teaford, Mark F; Livi, Kenneth J T; Weihs, Timothy P

2010-01-01

56

Experience versus complication rate in third molar surgery  

Microsoft Academic Search

OBJECTIVES: The records of 1087 patients who underwent surgical removal of third molar teeth were prospectively examined to analyse the possible relationship between postoperative complications and the surgeon's experience parameter. METHOD AND MATERIALS: Seven surgeons (three specialists in surgical dentistry [specialists SD] and four oral and maxillofacial Senior House Officers [OMFS residents]) carried out the surgical procedures. For each patient,

Waseem Jerjes; Mohammed El-Maaytah; Brian Swinson; Bilquis Banu; Tahwinder Upile; Sapna D'Sa; Mohammed Al-Khawalde; Boussad Chaib; Colin Hopper

2006-01-01

57

A influência do terceiro molar no apinhamento ântero-inferior The influence of the third molar on lower anterior crowding  

Microsoft Academic Search

The aim of the present study was to assess the influence of the third molar on lower anterior crowding, as well as to recommend the best clinical management for dental practitioners to solve this problem. The eruption, impaction, agenesis and prophylactic removal of lower crowding were evaluated by means of a review of the literature. It was possible to observe

Simone Freitas Sotero; Alexandre de Albuquerque Franco; Paulo Germano de Carvalho; Bezerra Falcão

58

Influence of third molar space on angulation and dental arch crowding.  

PubMed

The influence of the third molars on mandibular incisor crowding has been extensively studied but remains controversial. The purpose of this study was to ascertain whether, in Mongolian subjects, the lower third molar can affect anterior crowding and/or the inclination of teeth in the lower lateral segments. Panoramic radiographs, 45° oblique cephalograms, and dental casts were taken from Mongolian subjects (age range 18.3-24.1 years, mean 21.0 years) exhibiting impaction of all four third molars and an Angle Class I molar relationship. The Ganss ratio was calculated using panoramic radiographs, whereas the gonial angle and angulation of lower canines, premolars and molars were measured using 45° oblique cephalograms. Little's index of irregularity was calculated using dental casts. Significant relationships between the angulation of the third and second molars and between the first molars and second premolars were found. Conversely, there was no significant correlation between the angulation of third molars, first premolars and canines. The Ganss ratio calculations showed that the lower first and second molars and the second premolars inclined mesially if there was insufficient space for the lower third molars. However, there was no significant correlation between Little's index of irregularity and third molar angulation. Furthermore, although the third molar influences the lateral segments, no obvious relationship between the third molar and anterior crowding was observed. Therefore, the angulation of the third molar appears not to cause anterior crowding. PMID:22527908

Hasegawa, Yuh; Terada, Kazuto; Kageyama, Ikuo; Tsuchimochi, Takashi; Ishikawa, Fujiro; Nakahara, Sen

2013-01-01

59

Vapor-phase molar Kerr constant values from solution measurements  

NASA Astrophysics Data System (ADS)

A method is proposed for determination of molar Kerr constants (mK) by extrapolation of the values measured in a series of selected solvents. The mK values of 19 organic compounds were calculated. Most of the compounds cannot be studied in the vapor phase. The discrete-continuum solvation model was applied to investigate the influence of solvent nature on solubility of the compounds under investigation. It is shown that universal interactions between the solvent and solute molecules, including the dispersive, inductive, and dipole-dipole interactions, dominate the solvation process. The optimum model of internal field was chosen to determine the Kerr constant. The values of mKgas measured experimentally coincide with the values of mK??=0? that were obtained by extrapolation of mK?. Hence, this method can be applied to calculate the values of molar Kerr constants on the basis of measurements in solutions.

Prezhdo, Victor; Olan, Karol; Prezhdo, Oleg; Zubkova, Valentina

2015-01-01

60

Endodontic and post-endodontic management of a fused molar.  

PubMed

Treatment of fused teeth needs special care and attention to the bizarre anatomy. This paper describes root canal treatment of a fused carious tooth presenting with apical periodontitis. It is a rare case of fusion of the mandibular second molar with a paramolar. There is no literature regarding placement of crown over endodontically treated fused teeth. In this case, the fused teeth were endodontically treated and restored by a porcelain fused to metal crown. PMID:23965462

Gupta, Ruchi; Prakash, Vijay; Sharma, Mohit

2013-01-01

61

Partial molar volume of water in phonolitic glasses and liquids  

Microsoft Academic Search

The volumes and expansivities of four hydrous phonolite glasses and liquids have been measured by dilatometry from 300 K up to the glass transition and over a 50 K interval just above the glass transition. The partial molar volume of water is independent of the water content for the glass and liquid phases, with values of about 11.0ǂ.5 and 17.1ǂ.9

Ali M. Bouhifd; Alan Whittington; Pascal Richet

2001-01-01

62

Evaluation of lidocaine and mepivacaine for inferior third molar surgery  

Microsoft Academic Search

Objective: The aim of this study was to compare 2% lidocaine and 2% mepivacaine with 1:100,000 epinephrine for postoperative pain control. Study design: A group of 35 patients, both genders were recruited, whose had ages ranged from 13 to 27 years-old and had two inferior third molars in similar positions to be extracted. The cartridges were distributed to the patients

Gabriela Granja Porto; Cavalcanti Do; Egito Vasconcelos; Ana Cláudia; Amorim Gomes; Daniela Albert

63

From molecular to molar: a paradigm shift in behavior analysis.  

PubMed Central

A paradigm clash is occurring within behavior analysis. In the older paradigm, the molecular view, behavior consists of momentary or discrete responses that constitute instances of classes. Variation in response rate reflects variation in the strength or probability of the response class. The newer paradigm, the molar view, sees behavior as composed of activities that take up varying amounts of time. Whereas the molecular view takes response rate and choice to be "derived" measures and hence abstractions, the molar view takes response rate and choice to be concrete temporally extended behavioral allocations and regards momentary "responses" as abstractions. Research findings that point to variation in tempo, asymmetry in concurrent performance, and paradoxical resistance to change are readily interpretable when seen in the light of reinforcement and stimulus control of extended behavioral allocations or activities. Seen in the light of the ontological distinction between classes and individuals, extended behavioral allocations, like species in evolutionary taxonomy, constitute individuals, entities that change without changing their identity. Seeing allocations as individuals implies that less extended activities constitute parts of larger wholes rather than instances of classes. Both laboratory research and everyday behavior are explained plausibly in the light of concrete extended activities and their nesting. The molecular- view, because it requires discrete responses and contiguous events, relies on hypothetical stimuli and consequences to account for the same phenomena. One may prefer the molar view on grounds of elegance, integrative power, and plausibility. PMID:12144313

Baum, William M

2002-01-01

64

Efficacy of Postoperative Prophylactic Antibiotic Therapy in Third Molar Surgery  

PubMed Central

Introduction: Surgical extraction of mandibular third molar is the most frequently performed procedure in oral surgery. This procedure is associated with significant postoperative sequelae such as trismus, swelling, pain and infection. The need of antibiotic therapy during the removal of mandibular third molar has been a contentious issue. Method: This study investigated a regimen by using amoxycillin and metronidazole in one group and without using antibiotics in the other. Both the groups were assessed postoperatively on the 1st, 2nd, 5th, 7th and 10th days by the same observer for post operative mouth opening (interincisal distance), presence of a purulent discharge at the site of surgery, pain and swelling. Result: Overall, no statistically significant difference was seen between both the treatment groups when interincisal distance, pain, swelling and purulent discharge were considered. Conclusion: The results of this study failed to show any advantage which was associated with the routine postoperative use of antibiotics in asymptomatic third molar surgeries. PMID:24995236

Reddy B, Praveen

2014-01-01

65

Quality of life following third molar removal under conscious sedation  

PubMed Central

Aim: The aim of this study was to assess quality of life (QoL) and degree of satisfaction among outpatients subjected to surgical extraction of all four third molars under conscious sedation. A second objective was to describe the evolution of self-reported pain measured in a visual analogue scale (VAS) in the 7 days after extraction. Study design: Fifty patients received a questionnaire assessing social isolation, working isolation, eating and speaking ability, diet modifications, sleep impairment, changes in physical appearance, discomfort at suture removal and overall satisfaction at days 4 and 7 after surgery. Pain was recorded by patients on a 100-mm pain visual analogue scale (VAS) every day after extraction until day 7. Results: Thirty-nine patients fulfilled correctly the questionnaire. Postoperative pain values suffered small fluctuations until day 5 (range: 23 to 33 mm in a 100-mm VAS), when dicreased significantly. A positive association was observed between difficult ranked surgeries and higher postoperative pain levels. The average number of days for which the patient stopped working was 4.9. Conclusion: The removal of all third molars in a single appointment causes an important deterioration of the patient’s QoL during the first postoperative week, especially due to local pain and eating discomfort. Key words:Third molar removal, quality of life, sedation. PMID:22926461

Sancho-Puchades, Manuel; Berini-Aytés, Leonardo; Gay-Escoda, Cosme

2012-01-01

66

Primate molar crown formation times and life history evolution revisited.  

PubMed

Comparative studies have convincingly demonstrated that the pattern and timing of tooth emergence are highly correlated with life-history variables and brain size. Conversely, a firm relationship between molar formation time and life-history variables has not yet been established. It seems counterintuitive that one aspect of dental development should be correlated with life-history variables, whereas the other should not. In order to shed light on this apparent discrepancy this study analyzed all data on primate molar crown formations available in the published literature in relation to life-history variables, brain size, and female body mass. Crown formation times were found to be particularly highly correlated with both female body mass and brain size. Species that depart from the overall brain/body allometry by being relatively large-bodied, e.g., Gorilla gorilla and later Theropithecus oswaldi, also have shorter molar crown formation times than expected. The reverse is not found for species that depart from the overall brain/body allometry due to their larger brains, i.e., Homo sapiens. This finding is interpreted within an evolutionary and ecological framework. Specifically, by focusing on ecological commonalities, a scenario is proposed which may allow predictions to be made about the evolutionary history of other extinct primates also. If confirmed in future studies, crown formation time may again become a powerful tool in evolutionary enquiry. PMID:11748692

Macho, G A

2001-12-01

67

Extra-Oral Approach for Removal of Ectopic Impacted Lower Third Molar: A Case Report  

PubMed Central

Extra oral approach for removal of the lower third molar is uncommon. This case report illustrates an example of removal of lower third molar by extra-oral approach preserving the inferior dental nerve. PMID:25584338

Vishnu, Priya; Kannadasan, Kamal; Kengagsubbiah, Srivatsa; Kumar, Senthil

2014-01-01

68

Surgical extraction of mandibular third molar in pterygomandibular space: a case report.  

PubMed

Impacted mandibular third molars are located between the second mandibular molar and mandibular ramus. However, ectopic mandibular third molars with heterotopic positions are reported in the subcondylar or pterygomandibular space. The usual cause of malposition is a cyst or tumor, and malposition without a pathology is rare. This case report described an impacted mandibular third molar in the pterygomandibular space without any associated pathology. PMID:24471052

Lee, Young-Kyu; Park, Sung-Soo; Myoung, Hoon

2013-10-01

69

Molar uprighting by a nickel-titanium spring based on a setup model.  

PubMed

Molar uprighting is an important adjunctive treatment in orthodontics: repositioning the tilted molar eliminates the potentially pathologic condition and simplifies the ultimate restorative procedure. Although various methods for molar uprighting have been applied successfully, they still have some limitations and disadvantages in tooth movement. This article reports on a new clinical technique for molar uprighting with nickel-titanium springs based on a setup model. Two patients treated with this system are shown. PMID:24975006

Kim, MoonHee; Kim, Minji; Chun, Youn-Sic

2014-07-01

70

In vivo subcellular localization of Mal de Rio Cuarto virus (MRCV) non-structural proteins in insect cells reveals their putative functions  

SciTech Connect

The in vivo subcellular localization of Mal de Rio Cuarto virus (MRCV, Fijivirus, Reoviridae) non-structural proteins fused to GFP was analyzed by confocal microscopy. P5-1 showed a cytoplasmic vesicular-like distribution that was lost upon deleting its PDZ binding TKF motif, suggesting that P5-1 interacts with cellular PDZ proteins. P5-2 located at the nucleus and its nuclear import was affected by the deletion of its basic C-termini. P7-1 and P7-2 also entered the nucleus and therefore, along with P5-2, could function as regulators of host gene expression. P6 located in the cytoplasm and in perinuclear cloud-like inclusions, was driven to P9-1 viroplasm-like structures and co-localized with P7-2, P10 and {alpha}-tubulin, suggesting its involvement in viroplasm formation and viral intracellular movement. Finally, P9-2 was N-glycosylated and located at the plasma membrane in association with filopodia-like protrusions containing actin, suggesting a possible role in virus cell-to-cell movement and spread.

Maroniche, Guillermo A.; Mongelli, Vanesa C.; Llauger, Gabriela; Alfonso, Victoria; Taboga, Oscar [Instituto de Biotecnologia, CICVyA, Instituto Nacional de Tecnologia Agropecuaria (IB-INTA), Las cabanas y Los Reseros s/n. Hurlingham Cp 1686, Buenos Aires (Argentina)] [Instituto de Biotecnologia, CICVyA, Instituto Nacional de Tecnologia Agropecuaria (IB-INTA), Las cabanas y Los Reseros s/n. Hurlingham Cp 1686, Buenos Aires (Argentina); Vas, Mariana del, E-mail: mdelvas@cnia.inta.gov.ar [Instituto de Biotecnologia, CICVyA, Instituto Nacional de Tecnologia Agropecuaria (IB-INTA), Las cabanas y Los Reseros s/n. Hurlingham Cp 1686, Buenos Aires (Argentina)

2012-09-01

71

Sub-10-Minute Characterization of an Ultrahigh Molar Mass Polymer by Multi-detector Hydrodynamic Chromatography  

Technology Transfer Automated Retrieval System (TEKTRAN)

Molar mass averages, distributions, and architectural information of polymers are routinely obtained using size-exclusion chromatography (SEC). It has previously been shown that ultrahigh molar mass polymers may experience degradation during SEC analysis, leading to inaccurate molar mass averages a...

72

Restoration of Endodontically Treated Molars Using All Ceramic Endocrowns  

PubMed Central

Clinical success of endodontically treated posterior teeth is determined by the postendodontic restoration. Several options have been proposed to restore endodontically treated teeth. Endocrowns represent a conservative and esthetic restorative alternative to full coverage crowns. The preparation consists of a circular equigingival butt-joint margin and central retention cavity into the entire pulp chamber constructing both the crown and the core as a single unit. The case reports discussed here are moderately damaged endodontically treated molars restored using all ceramic endocrowns fabricated using two different systems, namely, CAD/CAM and pressed ceramic. PMID:24455318

Carlos, Roopak Bose; Thomas Nainan, Mohan; Pradhan, Shamina; Roshni Sharma; Benjamin, Shiny; Rose, Rajani

2013-01-01

73

Effect of bite force on orthodontic mini-implants in the molar region: Finite element analysis  

PubMed Central

Objective To examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction. Methods Five finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions: between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of 45° and 90° to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were 0°, 5°, and 10° to the long axis of the tooth. Results With regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at 90°. The maximum Von Mises stress increased with the inclination of the loading direction. Conclusions These results suggest that placement of OMIs between the second premolar and first molar at 45° to the cortical bone reduces the effect of bite force on OMIs. PMID:24228236

Lee, Hyeon-Jung; Lee, Kyung-Sook; Kim, Min-Ji

2013-01-01

74

Densities, excess molar volumes, and partial molar volumes for binary mixtures of water with monoethanolamine, diethanolamine, and triethanolamine from 25 to 80°C  

Microsoft Academic Search

We have measured densities of binary mixtures of water with monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) over the full range of compositions and over the temperature range from 25 to 80°C. Results of these measurements have been used in calculating excess molar volumes and partial molar volumes. Knowledge of the volumetric properties of these mixtures is useful in connection

Yadollah Maham; Tjoon T. Teng; Loren G. Hepler; Alan E. Mather

1994-01-01

75

An Evidenced Based Scoring System To Determine The Periodontal Prognosis On Molars  

PubMed Central

Background This retrospective study evaluated and assigned scores to six prognostic factors and derived a quantitative scoring system used to determine the periodontal prognosis on molar teeth. Methods Data were gathered on 816 molars in 102 patients with moderate to severe periodontitis. The six factors evaluated, age, probing depth, mobility, furcation involvement, smoking, and molar type, were assigned a numerical score based on statistical analysis. The sum of the scores for all factors was used to determine the prognosis score for each molar. Only patients with all first and second molars at the initial examination qualified for the study. All patients were a minimum of 15 years post treatment. Results The post treatment time ranged from 15 to 40 years and averaged 24 years. When the study was completed, 639 molars survived (78%), and of those surviving molars, 566 survived in health (89%). In molars with lower scores (1,2,and 3) the 15-year survival rates ranged from 99% to 96%. For scores 4, 5, 6 the 15 year survival rates ranged was 95% to 90% and for molars with scores of 7, 8, 9, and 10 the survival rates ranged from 86% to 67%. Conclusions Our results indicate that the periodontal prognosis on molars diagnosed with moderate to severe periodontitis can be calculated using an evidence-based scoring system. PMID:23725028

Miller, Preston D.; McEntire, Mark L.; Marlow, Nicole M.; Gellin, Robert G.

2014-01-01

76

[The pendulis appliance: a palatal miniscrew supported molar distalization device].  

PubMed

The maxillary molar distalization is a valuable therapeutic option in some clinical cases. Its biomechanics is challenging and difficult to obtain. Historically, various devices have been described offering successful solutions to this problem such as the Hilgers Pendulum Appliance (1992) and variants linked to mini screws which recently have shown interesting clinical potential. This article presents a new Pendulum variant using a miniscrew, the "pendulis". It follows the original concept (titanium-molybdenum alloy distalization springs and polymethyl-methacrylate pellet) but dental support is replaced by a single palatal miniscrew (median adults, para-median in children) to which the device is fixed by means of a metal welded cap easily positioned and removable by the practitioner. This allows for better control of the oral hygiene and completely controlled extraoral activation. Fabrication steps are described and instruction of use is illustrated with clinical documentation. PMID:25158749

Nappée-Miévilly, Magali; Nappée, François-Joseph; Kerbrat, Jean-Baptiste; Goudot, Patrick

2014-09-01

77

Molar extinction coefficients of solutions of some organic compounds  

NASA Astrophysics Data System (ADS)

Molar extinction coefficients of aqueous solutions of some organic compounds, viz. formamide (CH_{3}NO), N-methylformamide (C_{2}H_{5}NO), NN-dimethylformamide (C_{3}H_{7}NO), NN-dimethylacetamide (C_{4}H_{9}NO), 1,4-dioxane (C_{4}H_{8}O_{2}), succinimide (C_{4}H_{5}NO_{2}) and solutions of acetamide (C_{2}H_{5}NO) and benzoic acid (C_{7}H_{6}O_{2}) in 1,4-dioxane (C_{4}H_{8}O_{2}) have been determined by narrow beam gamma-ray transmission method at 81, 356, 511, 662, 1173 and 1332 keV. The experimental values of mass attenuation coefficients of these compounds have been used to calculate effective atomic numbers and electron densities. The additivity rule earlier used for aqueous solution has been extended to non-aqueous (1,4-dioxane) solutions.

Singh, Kulwant; Sandhu, G. K.; Lark, B. S.

2004-05-01

78

Mandibular molar rehabilitation using orthodontic extrusion associated with odontoplasty.  

PubMed

The aim of this clinical report is to describe the successful treatment of a mandibular first molar presenting an extensive fracture at the buccal aspect in a young patient. The extension of the fracture was a negative prognostic factor for tooth maintenance. An alternative clinical treatment was proposed since the patient was young and presented with good oral hygiene and periodontal health. The treatment was based on orthodontic forced eruption associated with odontoplasty. A 3-year follow-up after the surgical procedure demonstrated the maintenance of periodontal health and good plaque control. It can be concluded that orthodontic forced eruption associated with odontoplasty promoted favorable conditions for prosthetic rehabilitation and is a feasible procedure in the treatment of tooth fracture extended below the cementoenamel junction. PMID:22672712

Cesar-Neto, João Batista; Martos, Josué; Artifon, Luciano; Silveira, Luiz Fernando Machado; Michelon, Douver; Masotti, Alexandre Severo; Silva, José Carlos Maciel

2012-12-01

79

Four impacted fourth molars in a young patient: a case report  

PubMed Central

Summary The occurrence of supernumerary teeth is a relatively uncommon dental anomaly and it’s rare for patients to have impacted fourth molars in all quadrant. Aim of this work is to describe the presence of bilateral fourth molars in the maxilla and the mandible in a young male patient aged 22 years came to our hospital with acute pericoronal infection around unerupted third inferior molars. Routine radiographic examination revealed impacted inferior third molars but also unerupted bilateral upper and inferior fourth molars. The acute infection was treated by local measures and the patient was subsequently admitted for removal of third and fourth impacted upper and lower molars under general anesthesia. PMID:23741604

CLEMENTINI, M.; OTTRIA, L.; PANDOLFI, C.; AGRESTINI, C.; BARLATTANI, A.

2013-01-01

80

Management of mandibular first molar with four canals in mesial root  

PubMed Central

Successful root canal treatment depends on adequate cleaning, shaping, and filling of the root canal system. The presence of middle mesial (MM) root canal of mandibular molars has been reported by various authors. But incidence of four canals in mesial root of mandibular molar is very rare. The aim of this case report is to present and describe the identification and management of a mandibular first molar with four canals in the mesial root and single canal in the distal root. PMID:24082581

Subbiya, Arunajatesan; Kumar, Krishnamurthy Sathish; Vivekanandhan, Paramasivam; Prakash, Venkatachalam

2013-01-01

81

A Maxillary Second Molar with Two Separate Palatal Roots: A Case Report  

PubMed Central

Variations of dental root canals were reported by different authors. One of the rare variations is the presence of two separate palatal roots of maxillary molars, especially second maxillary molars. This case study reported a maxillary second molar with two separate palatal roots and a palatal bifurcation which was found during the periodontal flap surgery. Although these variations are rare, awareness of their presence would help in successful periodontal and endodontic treatment. PMID:24724127

Fakhari, E; Shokraneh, A

2013-01-01

82

UPPER VS. LOWER MOLARS FOR CEMENTUM ANNULI AGE DETERMINATION OF DEER  

Microsoft Academic Search

Ages were determined for 23 black-tailed deer (Odocoileus hemionus columbianus) and 14 white-tailed deer (0. virginianus) by examination of cementum annuli of both upper and lower 1st molars. Although estimated ages were virtually the same for both upper and lower molars, the clarity of annuli was significantly greater in upper molars for both species. Abstract: Ages were determined for 23

DALE R. McCULLOUGH; PAUL BEIER

83

Geometric morphometric 3D shape analysis and covariation of human mandibular and maxillary first molars.  

PubMed

Dental casts of 160 Greek subjects (80 males, 80 females) were scanned by a structured-light scanner. The upper and lower right first molar occlusal surface 3D meshes were processed using geometric morphometric methods. A total of 265 and 274 curve and surface sliding semilandmarks were placed on the upper and lower molar surfaces, respectively. Principal component analysis and partial least square analysis were performed to assess shape parameters. Molars tended to vary between an elongated and a more square form. The first two principal components (PCs), comprising almost 1/3 of molar shape variation, were related to mesiodistal-buccolingual ratios and relative cusp position. Distal cusps displayed the greatest shape variability. Molars of males were larger than those of females (2.8 and 3.2% for upper and lower molars respectively), but no shape dimorphism was observed. Upper and lower molar sizes were significantly correlated (r(2) = 0.689). Allometry was observed for both teeth. Larger lower molars were associated with shorter cusps, expansion of the distal cusp, and constriction of the mesial cusps (predicted variance 3.25%). Upper molars displayed weaker allometry (predicted variance 1.59%). Upper and lower molar shape covariation proved significant (RV = 17.26%, P < 0.0001). The main parameter of molar covariation in partial least square axis 1, contributing to 30% of total covariation, was cusp height, in contrast to the primary variability traits exhibited by PC1 and PC2. The aim of this study was to evaluate shape variation and covariation, including allometry and sexual dimorphism, of maxillary and mandibular first permanent molar occlusal surfaces. PMID:24009105

Polychronis, Georgios; Christou, Panagiotis; Mavragani, Maria; Halazonetis, Demetrios J

2013-10-01

84

Molar crown inner structural organization in Javanese Homo erectus.  

PubMed

This contribution investigates the inner organizational pattern (tooth tissue proportions and enamel-dentine junction morphology) of seven Homo erectus permanent molar crowns from the late Lower-early Middle Pleistocene Kabuh Formation of the Sangiran Dome (Central Java, Indonesia). The previous study of their external characteristics confirmed the degree of time-related structural reduction occurred in Javanese H. erectus, and also revealed a combination of nonmetric features which are rare in the Lower and early Middle Pleistocene dental record, but more frequently found in recent humans. In accordance with their outer occlusal morphology, the specimens exhibit a set of derived internal features, such as thick to hyperthick enamel, an incomplete expression of the crest patterns at the enamel-dentine junction (EDJ) level, a sharp EDJ topography. As a whole, these features differ from those expressed in some penecontemporaneous specimens/samples representing African H. erectus/ergaster and H. heidelbergensis, as well as in Neanderthals, but occur in recent human populations. Further research in virtual dental paleoanthropology to be developed at macroregional scale would clarify the polarity and intensity of the intermittent exchanges between continental and insular Southeast Asia around the Lower to Middle Pleistocene boundary, as well as should shed light on the still poorly understood longitudinal evolutionary dynamics across continental Asia. Am J Phys Anthropol 156:148-157, 2015 © 2014 Wiley Periodicals, Inc. PMID:25209431

Zanolli, Clément

2015-01-01

85

Molar volume dependence of the thermal conductivity in mixed cryocrystals  

NASA Astrophysics Data System (ADS)

The dependence of the thermal conductivity ? of solid solutions of cryocrystals on the molar volume is investigated theoretically in the Callaway approach under the assumption that the heat is transferred by mobile low-frequency phonons and, above the phonon mobility edge, by "localized" modes which migrate randomly from site to site. The phonon mobility edge ?0 is found from the condition that the phonon mean free path, which is governed by umklapp processes and scattering on point defects, cannot become smaller than one-half the phonon wavelength. The Bridgman coefficient g=-(? ln ?/? ln V)T is the weighted mean over these modes, which have strongly different volume dependences. For the example of the solid solution Kr1-c(CH4)c, where c is the mole fraction of the components, it is shown that with increasing methane concentration in krypton the Bridgman coefficient decreases, in good agreement with experiment, from g?9, characteristic for the pure crystals, to g?4.

Konstantinov, V. A.; Orel, E. S.; Revyakin, V. P.

2002-02-01

86

The third molar controversy: Framing the controversy as a public health policy issue  

Microsoft Academic Search

Purpose: This article summarizes the current research available concerning the removal of impacted third molars, and provides a background from which practitioners, public health policy advocates, and third-party payers can more objectively assess the the issues of appropriateness of care and overutilization of third molar surgery.Materials and Methods: A literature review was undertaken, with emphasis on noninterventional outcome studies and

William G Flick

1999-01-01

87

The transfer of occlusal forces through the maxillary molars: A finite element study  

Microsoft Academic Search

The morphology of the skeleton is known to reflect functional demand. A change in the intramaxillary position of molars can be expected to influence the transfer of occlusal forces to the facial skeleton. A finite element analysis allows us to simulate the displacement of a molar in relation to the well-defined morphology of the maxilla. Three 3-dimensional unilateral models of

Paolo M. Cattaneo; Michel Dalstra; Birte Melsen

2003-01-01

88

Radiographic Survey of Third Molar Development in Relation to Chronological Age Among Japanese Juveniles  

Microsoft Academic Search

The aim of the present study was to establish Japanese reference material on the third molar development of Japanese juveniles for forensic application. Observations were performed on the orthopantomograms of 1282 Japanese patients between the ages of 14.0 and 24.0 years. Demirjian formation stages of the maxillary and mandibular third molars were recorded for chronological evaluation of wisdom teeth and

Akita Hondo

89

Brief communication: correcting overestimation when determining two-dimensional occlusal area in human molars.  

PubMed

The robustness index (RI) is determined by multiplying dental mesiodistal and buccolingual diameters, and is used to estimate occlusal area. However, because teeth are not rectangular its calculation consistently causes overestimations. Moreover, teeth, in particular molars, are not identically shaped so overestimations vary. The current study seeks to determine the extent to which overestimations are affected by tooth shape and to improve RI's efficacy. Initially, 120 molars were sorted into six shape groups, which were determined by hypocone/hypoconulid expression. Three maxillary and three mandibular shape groups were set using the Arizona State University Dental Anthropology System. ANOVA results determined that RI overestimations, which averaged around 20%, were not the same for each shape category. Maxillary molars with large hypocones and mandibular molars with no hypoconulids were overestimated significantly less than the other molar groups. Regression-based correction formulae were generated and applied to the original sample. These formulae far more precisely estimated tooth area than RI and there were no differences in estimation based upon tooth shape. A subsequent validation study of 24 additional molars was undertaken to test the formulae on teeth not from the original sample. Overestimation/underestimation averaged 0.5% and was about the same for each of the tooth shape groups. Finally, six new correction formulae were generated using all 144 molars. The correction formulae provide, what is termed here, an adjusted robustness index (ARI), and it is recommended that ARI is used in future studies of molar occlusal area. PMID:21469080

Schmidt, Christopher; Ousley, Stephen; Schmidt, Molly

2011-06-01

90

Tooth anomalies associated with failure of eruption of first and second permanent molars  

Microsoft Academic Search

The occurrence of tooth anomalies in association with failure of the first and second molars to erupt was assessed in a sample of 1520 nonsyndromic subjects with uncrowded dental arches (mean age, 14 years 4 months) and compared with the prevalence rate calculated in a matched control group of 1000 subjects. The tooth anomalies examined included infraocclusion of deciduous molars,

T. Baccetti

2000-01-01

91

VERIFICAÇÃO DOS SINAIS RADIOGRÁFICOS MAIS FREQÜENTES DA RELAÇÃO DO TERCEIRO MOLAR INFERIOR COM O CANAL  

Microsoft Academic Search

The purpose of this study was to evaluate the type and frequency of the radiographic signs of an intimate relationship between the lower third molar and the mandibular canal through the use of panoramic radiography. The sample comprised 31 lower third molars that radiologically presented an intimate relationship with the mandibular canal. For evaluation purposes panoramic radiographs and the classifications

Ana Cláudia; Amorim GOMES; Belmiro Cavalcanti; Egito VASCONCELOS; Emanuel DIAS de Oliveira; Daniela Guimarães de Melo

92

Anatomical and histological features of C-shaped canals in mandibular second molars.  

PubMed

The mandibular second molar has many root canal variations. This investigation used two evaluation methods to examine the canal morphology of mandibular second molars having C-shaped canals. Fifteen extracted mandibular second molars with a conical root and C-shaped canal orifice were separated into two groups. A polyester cast resin technique allowed three-dimensional visualization of the root canal system in eight teeth; the remaining seven molars were prepared for histological examination in cross-section in the coronal, middle, and apical thirds for study under the light microscope. The results illustrated that C-shaped canals in mandibular second molars can vary in number and shape along the length of the root with the result that debridement, obturation, and restoration in this group may be unusually difficult. PMID:1809802

Melton, D C; Krell, K V; Fuller, M W

1991-08-01

93

A fine-structural analysis of mouse molar odontoblast maturation.  

PubMed

The first mandibular molars of the Swiss albino mice, 1 through 4 days of age, were fixed in glutaraldehyde or Karnovsky's fixative. The tissues were postfixed in OSO4, dehydrated and embedded in Epon. The prepolarizing, polarizing and secretory odontoblasts were described. The prepolarizing cells, located in the vicinity of the cervical loop, were mesenchymal-like in morphology. The cells of the polarizing stage possessed organelles indicative of protein synthesis. The nucleus was located proximally. Aperiodic fibers were evident in the wide basement membrane. The secretory odontoblasts were long, slender, polarized cells closely adjoining one another. Each odontoblast possessed six morphologically discernible regions: (1) an infranuclear region, limited in size and containing few cellular organelles; (2) a nuclear region, housing the oval nucleus and a few associated lamellae of rough endoplasmic reticulum as well as a limited number of mitochondria; (3) a supranuclear rough endoplasmic reticulum region, possessing an abundance of these organelles as well as some mitochondria and secretory vesicles; (4) a Golgi region, occupying the middle third of the cell, housing the elements of an extensive Golgi apparatus which was surrounded by peripherally located profiles of rough endoplasmic reticulum; additionally, this region contained smooth endoplasmic reticulum, mitochondria, numerous secretory granules and vesicles and occasional intracellular collagen fibers; (5) an apical rough endoplasmic reticulum region, containing a rough endoplasmic reticulum component that was less extensive than its supranuclear counterpart; in addition, this region was the one richest in mitochondria and contained a plethora of secretory vesicles and granules; (6) the odontoblastic process, a region mostly void of organelles, containing various secretory products, some of which appeared to be in the process of being released extracellularly into the surrounding dentin matrix. PMID:425821

Gartner, L P; Seibel, W; Hiatt, J L; Provenza, D V

1979-01-01

94

Analysis of quantitative trait locus effects on the size and shape of mandibular molars in mice.  

PubMed Central

While >50 genes have been found to influence the development of teeth in mice, we still know very little about the genetic basis for the adaptive characteristics of teeth, such as size and shape. We applied interval mapping procedures to Procrustes size and shape data obtained from 10 morphological landmarks on the mandibular molar row of the F(2) progeny from a cross between the LG/J and SM/J strains of mice. This revealed many more QTL for molar shape (18) than for molar centroid size (3), although levels of dominance effects were comparable among QTL for size and shape. Comparisons of patterns of Procrustes additive and dominance shape effects and ordination of QTL effects by principal components analysis suggested that the effects of the shape QTL were dispersed among the three molars and thus that none of these molars represents a genetically distinct developmental structure. The results of an analysis of co-occurrence of QTL for molar shape, mandible shape, and cranial dimensions in these mice suggested that many of the QTL for molar shape may be the same as those affecting these other sets of characters, although in some cases this could be due to effects of closely linked genes. PMID:11973311

Workman, Michael Scott; Leamy, Larry J; Routman, Eric J; Cheverud, James M

2002-01-01

95

Name: Seetin Question: In patients with mixed dentition, who have lost a single primary 2nd molar and require space  

E-print Network

Name: Seetin Question: In patients with mixed dentition, who have lost a single primary 2nd molar, comparison, outcome) P: Mixed dentition, lost single primary 2nd molar I: Unilateral space maintainer

Goldman, Steven A.

96

Partial molar volumes of isoniazid solutions in aqueous-ethanol mixtures at 298.15 K  

NASA Astrophysics Data System (ADS)

Densities (?) of antitubercular drug isoniazid solutions in water, aqueous-ethanol (20-80 vol % EtOH) and in pure ethanol at 298.15 K with different molar concentrations (0.01-0.16 mol dm-3) were measured. Experimental density data were used to calculate apparent molar volumes (? v ) of isoniazid in different media. The ? v data were fitted to Massons relation and partial molar volumes (?{/v 0}) of drug for infinitely dilute solution were determined for each solution. Experimental and derived properties were interpreted in terms of drug-solvent molecular interactions and structural fittings in studied systems.

Deosarkar, S. D.; Sawale, R. T.; Tawde, P. D.; Kalyankar, T. M.

2015-02-01

97

Hypohyperdontia: Agenesis of three third molars and mandibular centrals associated with midline supernumerary tooth in mandible.  

PubMed

Agenesis of teeth in a patient who also presents with a supernumerary tooth is one of the rare numerical anomalies in human dentition. Agenesis of third molars was shown to be associated with other missing permanent teeth. A review of literature on hypodontia including third molar agenesis, hyperdontia and a concomitant presence of these two conditions which is termed as hypohyperdontia is presented along with a case showing agenesis of three third molars, both mandibular central incisors and a midline supernumerary tooth. PMID:22114403

Nuvvula, Sivakumar; Kiranmayi, M; Shilpa, G; Nirmala, S V S G

2010-07-01

98

Molar development in common chimpanzees (Pan troglodytes) T.M. Smith a,*, D.J. Reid b  

E-print Network

Molar development in common chimpanzees (Pan troglodytes) T.M. Smith a,*, D.J. Reid b , M.C. Dean c and cuspal enamel thickness both vary within a cusp type, among cusps, and among molars, resulting in marked, and outer enamel) within and among cusp types and among molar types. Significantly increasing trends

Smith, Tanya M.

99

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.  

Code of Federal Regulations, 2014 CFR

...you use multiple venturis and you calibrated each venturi independently to determine a separate discharge coefficient, C d (or calibration coefficient, K v ), for each venturi, calculate the individual molar flow rates through...

2014-07-01

100

Endodontic management of a maxillary molar with formation supradentalis: A case report  

PubMed Central

Anatomic variations may be observed in the crown or in the roots of maxillary molars. In rare instances, crown and root morphology, both show variations. Occurrence of paramolar cusp on the occlusal surface as central cusp or on the buccal surface as parastyle has been frequently reported in maxillary molars. However, presence of paramolar cusp on the palatal surface has not been reported. ‘Formation supradentalis’ is a condition in which supernumerary cusp is associated with a supernumerary root in a molar. The occurrence of such concomitant corono-radicular morphology is multifactorial, that is primary polygenic with secondary environmental influences. This case reports the diagnosis and endodontic management of Formation-supradentalis that had six cusps and four roots in the maxillary first molar. The tooth exhibited a prominent paramolar palatal cusp and cusp of Carabelli along with a supernumerary palatal root. To the best of author's knowledge, this is the first documentation of endodontic management of Formation supradentalis. PMID:25298653

Shah, Dipali Y.; Jadhav, Ganesh R.

2014-01-01

101

Effects of ozone therapy on pain, swelling, and trismus following third molar surgery.  

PubMed

The aim of this study was to evaluate the efficacy of therapeutic ozone application in the management of pain, swelling, and trismus associated with the surgical removal of impacted mandibular third molars. Sixty consecutive patients with asymptomatic bilateral impacted mandibular third molars were recruited into the study. Randomly, by use of envelops, the molar on one side was extracted and ozone therapy was given (study side); the molar on the other side was extracted 2 weeks later and sham ozone therapy was given (negative control side). The mean age of the 60 patients was 22.6±2.3 years (range 18-25 years). No differences were found between the two sides for mouth opening or swelling. The degree of pain and the number of analgesic tablets taken was significantly lower for the study side. This study showed ozone therapy to have a positive effect on OHIP-14 questionnaire results. PMID:24332588

Kazancioglu, H O; Kurklu, E; Ezirganli, S

2014-05-01

102

Root Canal Morphology of Mandibular First Permanent Molars in an Indian Population  

PubMed Central

An in vitro study was performed to determine the number of roots, root canals per tooth, root canal configurations, and frequency of isthmi and apical deltas in mandibular first permanent molars in an Indian population. Hundred and fifty mandibular first permanent molars were collected and subjected to clearing technique. The cleared teeth were examined in a stereomicroscope under 7.5x magnifications. The canal configurations were categorized using Vertucci's classification. Overall 94.6% of the mandibular first molars had two roots, and 5.3% had extradistal roots (distolingual root). In addition, 64% of the specimens had three root canals, and 36% had four root canals. The most common canal configurations of mesial and distal roots were Vertucci type IV (54%) and type I (65.3%), respectively. Clinician should be aware of the complex root canal morphology of mandibular first molars among the Indian population before and during the root canal treatment. PMID:22287965

Chourasia, Hemant Ramesh; Meshram, Ganesh K.; Warhadpande, Manjusha; Dakshindas, Darshan

2012-01-01

103

Indications for removal of impacted mandibular third molars: a single institutional experience in Libya  

Microsoft Academic Search

Aims  To investigate the various indications for the removal of impacted lower third molars in a dental school in Libya.\\u000a \\u000a \\u000a \\u000a Methods  The records of all patients who underwent a surgical removal of a lower third molar over a 3 year period were reviewed retrospectively.\\u000a The indications for removal were classified into 10 groups. Radiographs were also studied to determine angular position as

B. Krishnan; Mohammad Hossni El Sheikh; El-Gehani Rafa; H. Orafi

2009-01-01

104

Unusual maxillary first molar with 2 palatal canals within a single root: a case report.  

PubMed

A case report is presented regarding a maxillary first molar with 5 canals. The morphology is atypical because it is characterized by a single palatal root with 2 canals with separate orifices joining in the apical third. A literature review pertaining to the morphology of maxillary first molars is discussed. Modifications to the normal access opening and examination of the pulpal floor for additional canals are stressed. PMID:11370279

Johal, S

2001-04-01

105

Intrusion of an overerupted molar using orthodontic miniscrew implant: A preprosthodontic therapy.  

PubMed

The purpose of this case report is to demonstrate the use of orthodontic miniscrew implant in the intrusion of overerupted molar as a preprosthodontic therapy. A 37-year-old woman with an overerupted maxillary right first molar encroaching on the opposing mandibular edentulous space was successfully intruded using a single miniscrew implant and partial fixed orthodontic appliance. The prosthodontic clinician may adopt this conservative and cost-effective strategy in their routine practice and avoid clinical crown reduction. PMID:25191088

Sivakumar, Indumathi; Sivakumar, Arunachalam

2014-07-01

106

Intrusion of an overerupted molar using orthodontic miniscrew implant: A preprosthodontic therapy  

PubMed Central

The purpose of this case report is to demonstrate the use of orthodontic miniscrew implant in the intrusion of overerupted molar as a preprosthodontic therapy. A 37-year-old woman with an overerupted maxillary right first molar encroaching on the opposing mandibular edentulous space was successfully intruded using a single miniscrew implant and partial fixed orthodontic appliance. The prosthodontic clinician may adopt this conservative and cost-effective strategy in their routine practice and avoid clinical crown reduction. PMID:25191088

Sivakumar, Indumathi; Sivakumar, Arunachalam

2014-01-01

107

Evaluation of radius of gyration and intrinsic viscosity molar mass dependence and stiffness of hyaluronan.  

PubMed

Nine hyaluronan (HA) samples were fractionated by size-exclusion chromatography, and molar mass (M), radius of gyration (Rg), and intrinsic viscosity ([eta]) were measured in 0.15 M NaCl at 37 degrees C by on-line multiangle light scattering and viscometer detectors. Using such method, we investigated the Rg and [eta] molar mass dependence for HA over a very wide range of molar masses: M ranging from 4 x 10(4) to 5.5 x 10(6) g/mol. The Rg and the [eta] molar mass dependence found for HA showed a meaningful difference. The Rg = f(M) power law was substantially linear in the whole range of molar masses explored with a constant slope of 0.6. In contrast, the [eta] = f(M) power law (Mark-Houwink-Sakurada plot) showed a marked curve shape, and a linear regression over the whole range of molar masses does not make sense. Also the persistence length (stiffness) for HA was estimated. The persistence length derived by using both the Odijk's model (7.5 nm from Rg vs M data) and the Bohdanecky's plot (6.8 nm from [eta] vs M data) were quite similar. These persistence length values are congruent with a semistiff conformation of HA macromolecules. PMID:14606912

Mendichi, Raniero; Soltés, Ladislav; Giacometti Schieroni, Alberto

2003-01-01

108

An in vitro assessment of type, position and incidence of isthmus in human permanent molars  

PubMed Central

Root canal anatomical complexities, such as isthmus, may limit the action of the endodontic instruments, irrigant solutions and intracanal medications, leading to endodontic treatment failure. Objectives This in vitro study assessed the type, position and incidence of isthmus in human permanent molars. Material and Methods One hundred and twenty eight upper and lower first and second permanent molars were analyzed. The roots were embedded in transparent resin, and then split at different distances from the apex (1.0-2.5-4.0-5.5-7.0 mm). Following the sample examination in stereomicroscope, the data were submitted to chi-square statistical test at a 5% significance level. Results The highest isthmus incidence was at 7.0 mm from the root apex in all samples, except the distal root of lower molars (at 5.5 mm). In upper and lower molars, type V (complete isthmus with a continuous opening between the two main root canals) was the most common classification of isthmus (28.8%). In the mesial root of first and second mandibular molars, type IV had the highest incidence (36% and 23.9%, respectively). Conclusion It was concluded that isthmus was widely found in flat roots, with a low percentage in areas close to the apex. In upper and lower molars, these structures were most frequently found at 7 mm from the apex. PMID:25141198

de LIMA, Fernando José Camello; MONTAGNER, Francisco; JACINTO, Rogério Castilho; AMBROSANO, Glaucia Maria Bovi; GOMES, Brenda Paula Figueiredo de Almeida

2014-01-01

109

Analysis and evaluation of relative positions of mandibular third molar and mandibular canal impacts  

PubMed Central

Objectives This study used cone-beam computed tomography (CBCT) images to categorize the relationships between the mandibular canal and the roots and investigated the prevalence of nerve damage. Materials and Methods Through CBCT images, contact and three-dimensional positional relationships between the roots of the mandibular third molar and the mandibular canal were investigated. With this data, prevalence of nerve damage according to the presence of contact and three-dimensional positional relationships was studied. Other factors that affected the prevalence of nerve damage were also investigated. Results When the mandibular third molar and the mandibular canal were shown to have direct contact in CBCT images, the prevalence of nerve damage was higher than in other cases. Also, in cases where the mandibular canal was horizontally lingual to the mandibular third molar and the mandibular canal was vertically at the cervical level of the mandibular third molar, the prevalence of nerve damage was higher than in opposite cases. The percentage of mandibular canal contact with the roots of the mandibular third molar was higher when the mandibular canal was horizontally lingual to the mandibular third molar. Finally, the prevalence of nerve damage was higher when the diameter of the mandibular canal lumen suddenly decreased at the contact area between the mandibular canal and the roots, as shown in CBCT images. Conclusion The three-dimensional relationship of the mandibular third molar and the mandibular canal can help predict nerve damage and can guide patient expectations of the possibility and extent of nerve damage. PMID:25551092

Kim, Hang-Gul

2014-01-01

110

The Component Slope Linear Model for Calculating Intensive Partial Molar Properties: Application to Waste Glasses  

SciTech Connect

Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOH-NaAl(OH{sub 4}H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results detennined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components.

Reynolds, Jacob G. [Washington River Protection Solutions, Richland, WA (United States)

2013-01-11

111

Compositional dependent partial molar volume and compressibility of CO2 in rhyolite, phonolite and basalt glasses  

NASA Astrophysics Data System (ADS)

Carbon dioxide is the second most abundant volatile in magmatic systems and plays an important role in many magmatic processes, e.g. partial melting, volatile saturation, outgassing. Despite this relevance, the volumetric properties of carbon-bearing silicates at relevant pressure and temperature conditions remain largely unknown because of considerable experimental difficulties associated with in situ measurements. Density and elasticity measurements on quenched glasses can provide an alternative source of information. For dissolved water, such measurements indicate that the partial molar volume is independent of compositions at ambient pressure [1], but the partial molar compressibility is not [2, 3]. Thus the partial molar volume of water may depend on melt composition at elevated pressure. For dissolved CO2, no such data is available. In order to constrain the effect of magma composition on the partial molar volume and compressibility of dissolved carbon, we determined the density and elasticity for three series of carbon-bearing basalt, phonolite and rhyolite glasses, quenched from 3.5 GPa and relaxed at ambient pressure. The CO2 content varies between 0 to 3.90 wt% depending on the glass composition. Glass densities were determined using the sink/float method in a diiodomethane (CH2I2) - acetone mixture. Brillouin measurements were conducted on relaxed and unrelaxed silicate glasses in platelet geometry to determine the compressional (VP) and shear (VS) wave velocities and elastic moduli. The partial molar volume of CO2 in rhyolite, phonolite and basalt glasses is 25.4 ± 0.9, 22.1 ± 0.6 and 26.6 ±1.8 cm3/mol, respectively. Thus, unlike for dissolved water, the partial molar volume of CO2 displays a resolvable compositional effect. Although the composition and CO2/carbonate speciation of the phonolite glasses is intermediate between that of the rhyolite and basalt glasses, the molar volume is not. Similar to dissolved water, the partial molar bulk modulus of CO2 displays a strong compositional effect. If these compositional dependencies persist in the analogue melts, the partial molar volume of dissolved CO2 will depend on melt composition, both at low and elevated pressure. Thus, for CO2-bearing melts, a full quantitative understanding of density dependent magmatic processes, such as crystal fractionation, magma mixing and melt extraction will require in situ measurements for a range of melt compositions. [1] Richet, P. et al., 2000, Contrib Mineral Petrol, 138, 337-347. [2] Malfait et al. 2011, Am. Mineral. 96, 1402-1409. [3] Whittington et al., 2012, Am. Mineral. 97, 455-467.

Lerch, P.; Seifert, R.; Malfait, W. J.; Sanchez-Valle, C.

2012-12-01

112

Gender Determination Using Diagonal Measurements of Maxillary Molar and Canine Teeth in Davangere Population  

PubMed Central

Background: Mesiodistal and buccolingual measurements of the teeth have been the traditional means of determining gender which sometimes are difficult to measure. Aims and Objectives: To assess the degree of sexual dimorphism in upper permanent canines and first molars using diagonal diameters and to evaluate the applicability of diagonal measurements in sex determination. Materials and Methods: Mesiobuccal-distolingual (MBDL) and distobuccal-mesiolingual (DBML) measurements of the crown and cervix of maxillary canine and maxillary molar were taken using digital vernier callipers in 100 upper dental casts obtained from 50 males and 50 females of the age group of 17-25 y. Results: With step wise discriminant function analysis, results were statistically significant with males showing higher diagonal measurement values. The classification accuracy for males was 69% and in females was 73% with overall accuracy of 71%. Results showed that canines exhibited highest accuracy with cervical measurements being more dimorphic. MBDL measurements were found to be more reliable. Most dimorphicmeasurements included right molar cervical MBDL, left molar cervical MBDL followed by right and left molar crown MBDL. Conclusion: In cases of tooth rotations, crowding, certain fillings and attritions where traditional mesio-distal and bucco-lingual measurements are not applicable, diagonal measurements could be of help in predicting gender.

Tarigoppula, Ratna Kumari V. N.; Kulkarni, Pavan G; BS, Anil

2014-01-01

113

Mandibular cephalometric characteristics of a Saudi sample of patients having impacted third molars  

PubMed Central

Objective To evaluate the cephalometric characteristics of mandibles of Saudi patients having impacted third molars and to compare them to those of patients having normally erupted third molars. Material and methods One hundred and twenty-one Saudi adult subjects (59 females and 62 males; age: 20–40 years) were divided into two groups based on the status of the mandibular third molars: (1) impaction group and (2) normal group. Means and standard deviations of 21 cephalometric measurements related to mandibular geometry were measured and compared between the two groups using the unpaired t-test. Males and females in the impaction group were also compared with their equivalent subgroups in the normal group using the unpaired t-test. Results Anteroposteriorly, space distal to second molar, ramal width and mandibular body length were significantly less in the impaction group than in the control group. In addition, posterior teeth were more upright in the impaction group. Vertically, posterior alveolar height was significantly less in the impaction group. The Y-axis was significantly increased in the impaction group. The significance of these measurements was variable between males and females. Conclusions Third-molar impactions in the Saudis living in the Western region of Saudi Arabia were more likely to occur when inadequate retromolar space is present. This can be attributed to certain mandibular skeletal and dental features, among which the increased width of mandibular ramus and backward inclination of posterior teeth seem to be the most influencing factors in both sexes. PMID:23960502

Hassan, Ali H.

2010-01-01

114

Root and Canal Morphology of Mandibular Third Molars in an Iranian Population  

PubMed Central

Background and aims A through knowledge of the root canal morphology is required for successful endodontic ther-apy. The aim of this study was to investigate the root and canal morphology of mandibular third molars in Kerman, a prov-ince in southeast of Iran. Materials and methods One-hundred-fifty extracted mandibular third molars were collected randomly from different dental clinics in Kerman. The root canal anatomy and morphology of each tooth was carefully studied using a clearing tech-nique. Root number and morphology, number of canals per root, root canal configuration according to Vertucci classifica-tion, and incidence of dilacerated roots and C-shaped canals in mandibular third molars were evaluated under stereomicro-scope with ×2 to ×3 magnifications. Results From the total of 150 mandibular third molars studied, 21% had one root. The majority of teeth (73%) had two roots. 5.5% of the teeth had three roots. The incidence of C-shaped canal was 3.5% in this study and 8% of the teeth had at least one dilacerated root. Conclusion Although root canal anatomy and morphology of mandibular third molars is very variable having two roots seems to be the normal anatomy for these teeth. PMID:22991643

Kuzekanani, Maryam; Haghani, Jahangir; Nosrati, Hossein

2012-01-01

115

Anatomical study of C-shaped canals in mandibular second molars by analysis of computed tomography.  

PubMed

The aim of this study was to investigate the prevalence and configuration of the C-shaped canal using serial axial computed tomography images of the mandibular second molars that had not been restored severely or treated endodontically, and to compare the thickness of the remaining tooth structure from the center of the canal to the outer surface of the deepest groove area in C-shaped mandibular second molar to that of "danger zone of perforation" in normal mandibular second molar. This distance was measured at the cervical, middle, and apical third level each. From 220 teeth, C-shaped canals were found in 98 teeth (44.5%). Almost all the grooves were directed lingual (99%). The continuous C-shaped canal was the most frequently found (49%) and the separated canal was the least (17.4%). The thinnest remaining tooth structure in the groove area of the C-shaped mandibular second molar was not different from that of the danger zone of normal mandibular second molar at the three levels (p > 0.05). PMID:16410060

Jin, Guang-Chun; Lee, Seong-Jong; Roh, Byoung-Duck

2006-01-01

116

Cross-sectional study of correlation between mandibular incisor crowding and third molars in young Brazilians  

PubMed Central

Objectives: The aim of this study was to evaluate transversally the clinical correlation between lower incisor crowding and mandible third molar. Study Design: Three hundred healthy volunteers (134 male and 166 female), aged 20.4 (±2.4) years-old were submitted to a complete clinical examination and filled up a questionnaire about gender, age, total teeth number and presence or absence of superior and inferior third molar. After a recent panoramic radiography were evaluated. The multiple logistic regression showed that none of the studied factors influenced the mandibular incisor crowding. Results: The proportion of both molars present or both absent was higher than the other conditions (Chi-square, p<.0001). The multiple logistic regression showed that any of the studied factors, influenced (p>.05) the mandibular incisor crowding. Despite the statistical significance, wear orthodontics appliances showed a little correlation (odds ratios < 1.0) in the mandibular incisor crowding. Conclusion: Presence of maxillary and/or mandibular third molars has no relation with the lower incisor crowding. Key words:Malocclusion, third molars, lower incisor crowding, mandible. PMID:23385508

Karasawa, Lilian H.; Groppo, Francisco C.; Prado, Felippe B.; Caria, Paulo H F.

2013-01-01

117

Evaluation of Molar Volume Effect for Calculation of Diffusion in Binary Systems  

NASA Astrophysics Data System (ADS)

This article relates the theoretical evaluation of the effect of a molar volume change in the diffusion profile of a binary system. This study is based on the regression fit of a diffusion profile using a selected function in an inverse form. For the calculation of concentration-dependent diffusivity according to the Sauer and Freise (and Wagner) treatment of the Boltzmann-Matano relation, this inverse regression function is further modified by the inclusion of molar volume, which is dependent on the molar composition of a diffusing two-component mixture. Following the conversion of the initial relation to the form that enables the direct integration of the used inverse function, which fits the diffusion profile, the formulas for the analytical calculation of diffusivity are obtained. These formulas are derived both for the linear change in molar volume in the diffusion profile corresponding to Vegard's rule and for the case of the positive or negative deviations from the linearity representing the swell or shrink course V m. The analysis results show that the drop and swell shapes of the course of molar volume in a diffusion profile of the binary system increase the resulting diffusivity. Conversely, the increase of V m and its shrink course are factors that lower diffusivity. The regression function that was used in its inverse form was suitable for fitting the diffusion profile of any asymmetrical shape. The derived relations are therefore practically applicable for the direct analytical calculation of concentration-dependent diffusivity in binary systems.

Vach, Marek; Svojtka, Martin

2012-12-01

118

Brief communication: possible third molar impactions in the hominid fossil record.  

PubMed

Impacted third molars affect 15%-20% of modern Americans and Western Europeans. In contrast, third molar impactions have not been reported in the early hominid fossil record. It is uncertain whether the lack of reports reflects an absence of impactions or a failure to recognize them. This communication is intended to raise awareness of the possibility of impactions by describing the appearance of impacted teeth and by noting two possible instances of impaction in early hominids. Specifically, the mandibular third molars of the Sterkfontein specimen, STS52b (Australopithecus africanus), and the left maxillary third molar of the Lake Turkana specimen, KNM-WT 17400 (Australopithecus boisei), are positioned in a manner which suggests that they would not have erupted normally. Both specimens also exhibit strong crowding of the anterior dentition, providing further support for the view that these individuals lacked sufficient space for normal eruption of the third molars. Other published reports of dental crowding in the hominid fossil record are noted, and it is suggested that more attention be paid to dental impaction and dental crowding in hominid evolution. PMID:8372939

Gibson, K R; Calcagno, J M

1993-08-01

119

Evc regulates a symmetrical response to Shh signaling in molar development.  

PubMed

Tooth morphogenesis involves patterning through the activity of epithelial signaling centers that, among other molecules, secrete Sonic hedgehog (Shh). While it is known that Shh responding cells need intact primary cilia for signal transduction, the roles of individual cilia components for tooth morphogenesis are poorly understood. The clinical features of individuals with Ellis-van Creveld syndrome include various dental anomalies, and we show here that absence of the cilial protein Evc in mice causes various hypo- and hyperplasia defects during molar development. During first molar development, the response to Shh signaling is progressively lost in Evc-deficient embryos and, unexpectedly, the response consistently disappears in a buccal to lingual direction. The important role of Evc for establishing the buccal-lingual axis of the developing first molar is also supported by a displaced activity of the Wnt pathway in Evc mutants. The observed growth abnormalities eventually manifest in first molar microdontia, disruption of molar segmentation and symmetry, root fusions, and delayed differentiation. Analysis of our data indicates that both spatially and temporally disrupted activities of the Shh pathway are the primary cause for the variable dental anomalies seen in patients with Ellis-van Creveld syndrome or Weyers acrodental dysostosis. PMID:23315474

Nakatomi, M; Hovorakova, M; Gritli-Linde, A; Blair, H J; MacArthur, K; Peterka, M; Lesot, H; Peterkova, R; Ruiz-Perez, V L; Goodship, J A; Peters, H

2013-03-01

120

Stress distribution produced by correction of the maxillary second molar in buccal crossbite.  

PubMed

The purpose of this study was to evaluate the stress distribution produced in the dentoalveolar system by a maxillary posterior crossbite appliance used for the correction of maxillary second molars in buccal crossbite. A photoelastic model was fabricated using a photoelastic material (PL-3) to simulate alveolar bone and ivory-colored resin teeth. The model was anteriorly and posteriorly observed with a circular polariscope and photographically recorded before and after activation of the maxillary posterior crossbite appliance. An uncontrolled palatal tipping and a rotating force were generated when the traction force was applied on the palatal surface of the maxillary second molar. A controlled tipping and an intrusive force were generated when the traction force was applied on the buccal surface of the maxillary second molar. PMID:12401047

Yoon, Young-Jooh; Jang, Sung-Ho; Hwang, Gab-Woon; Kim, Kwang-Won

2002-10-01

121

Maxillary first molar with an O-shaped root morphology: report of a case.  

PubMed

This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation because of difficulty in negotiating all canals. Periapical radiographs and cone-beam computed tomography (CBCT) were taken. All roots were connected and fused to one root, and all canals seemed to be connected to form an O-shape. The apical 3 mm of the root were resected and retrograde filled with resin-modified glass ionomer. Intentional replantation as an alternative treatment could be considered in a maxillary first molar having an unusual O-shaped root. PMID:24008268

Shin, Yooseok; Kim, Yemi; Roh, Byoung-Duck

2013-12-01

122

Maxillary first molar with an O-shaped root morphology: report of a case  

PubMed Central

This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation because of difficulty in negotiating all canals. Periapical radiographs and cone-beam computed tomography (CBCT) were taken. All roots were connected and fused to one root, and all canals seemed to be connected to form an O-shape. The apical 3 mm of the root were resected and retrograde filled with resin-modified glass ionomer. Intentional replantation as an alternative treatment could be considered in a maxillary first molar having an unusual O-shaped root. PMID:24008268

Shin, Yooseok; Kim, Yemi; Roh, Byoung-Duck

2013-01-01

123

Tuning of magnetic properties in cobalt ferrite by varying Fe+2 and Co+2 molar ratios  

NASA Astrophysics Data System (ADS)

Different grades of magnetic cobalt ferrite (CoFe2O4) nanoparticles were synthesized with various molar ratios of Fe+2 to Co+2 ions in the initial salt solutions by the co-precipitation method. The crystal structure and morphology of the nanoparticles are obtained from X-ray diffraction and transmission electron microscopy studies. Fourier transform infrared spectroscopy analysis exhibited the Fe-O stretching vibration ~540 cm-1, confirming the formation of metal oxide. The magnetic studies demonstrate that all of the nanoparticles are superparamagnetic at 300 K. The saturation magnetization and coercivity of the CoFe2O4 nanoparticles are affected by the molar ratios of Fe+2 to Co+2 ions. Among all the synthesized nanoparticles, the system with 75:25 molar ratio of Fe+2 to Co+2 ions with a particle size of 13 nm showed a high magnetization of 90 emu/g.

Biswal, Dipti; Peeples, Brianna N.; Peeples, Caryn; Pradhan, Aswini K.

2013-11-01

124

Asymmetry in mesial root number and morphology in mandibular second molars: a case report  

PubMed Central

Ambiguity in the root morphology of the mandibular second molars is quite common. The most common root canal configuration is 2 roots and 3 canals, nonetheless other possibilities may still exist. The presence of accessory roots is an interesting example of anatomic root variation. While the presence of radix entomolaris or radix paramolaris is regarded as a typical clinical finding of a three-rooted mandibular second permanent molar, the occurrence of an additional mesial root is rather uncommon and represents a possibility of deviation from the regular norms. This case report describes successful endodontic management of a three-rooted mandibular second molar presenting with an unusual accessory mesial root, which was identified with the aid of multiangled radiographs and cone-beam computed tomography imaging. This article also discusses the prevalence, etiology, morphological variations, clinical approach to diagnosis, and significance of supernumerary roots in contemporary clinical dentistry. PMID:24516829

Shetty, Shashit; Shekhar, Rhitu

2014-01-01

125

Formation of polyelectrolyte complexes with diethylaminoethyl dextran: charge ratio and molar mass effect.  

PubMed

The formation of polyelectrolyte complexes (PECs) between carboxymethyl pullulan and DEAE Dextran, was investigated, in dilute solution, with emphasis on the effect of charge density (molar ratio or pH) and molar masses. Electrophoretic mobility measurements have evidenced that insoluble PECs (neutral electrophoretic mobility) occurs for charge ratio between 0.6 (excess of polycation) and 1 (stoichiometry usual value) according to the pH. This atypical result is explained by the inaccessibility of some permanent cationic charge when screened by pH dependant cationic ones (due to the Hoffman alkylation). Isothermal titration calorimetry (ITC) indicates an endothermic formation of PEC with a binding constant around 10(5) L mol(-1). Finally asymmetrical flow field flow fractionation coupled on line with static multi angle light scattering (AF4/MALS) evidences soluble PECs with very large average molar masses and size around 100 nm, in agreement with scrambled eggs multi-association between various polyelectrolyte chains. PMID:25256478

Le Cerf, Didier; Pepin, Anne Sophie; Niang, Pape Momar; Cristea, Mariana; Karakasyan-Dia, Carole; Picton, Luc

2014-11-26

126

Survival and success rate of one-piece implant inserted in molar sites  

PubMed Central

Background: Recently, the use of one-piece implants (OPI) has become more popular. Since no reports specifically focus on OPIs inserted in molar areas, a retrospective study has been performed. Materials and Methods: A series of 36 OPIs (Diamond; BIOIMPLANT, Milan, Italy) were inserted into the molar area of patients admitted at the Dental Clinic, University of Chieti, Italy, for oral rehabilitation between January and December 2010. Results: In our series survival rate (SVR) and success rate (SCR) were 91.7% and 97%, respectively. Statistical analysis demonstrated that no studied variable has an impact on survival (i.e., lost implants) as well as on clinical success (i.e., crestal bone resorption). Conclusion: OPIs are reliable devices for oral rehabilitation in the molar areas. PMID:23814575

Carinci, Francesco

2012-01-01

127

Endodontic Management of Maxillary Second Molar with Two Palatal Roots: A Report of Two Cases  

PubMed Central

Endodontic treatment may sometimes fail because morphological features of the tooth adversely affect the treatment protocol. Maxillary second molars are recognized as usually having a single palatal root with a single palatal canal. The incidence of second palatal root in the maxillary second molar is very rare. Two cases are presented in this paper describing the endodontic management of a four-rooted maxillary second molar with two distinct palatal roots and canals and two distinct buccal roots and canals. Clinical examination and radiographs showed the presence of two palatal roots during the root canal procedure. The canals were biomechanically prepared with crown-down technique and obturated using lateral condensation technique with AH-Plus sealer. PMID:23304565

2012-01-01

128

Prevention of Localized Osteitis in Mandibular Third-Molar Sites Using Platelet-Rich Fibrin  

PubMed Central

Purpose. To review our experience utilizing platelet rich fibrin (PRF), which is reported to aid in wound healing of extraction sites, for the prevention of localized osteitis following lower third-molar removal. Materials and Methods. PRF was placed in the mandibular third-molar extraction sites, 200 sites total, on 100 consecutive patients treated in our practice, by the authors. The patients were managed with standard surgical techniques, intraoperative IV antibiotic/steroid coverage, and routine postoperative narcotic analgesics/short-term steroid coverage. All patients were reevaluated for localized osteitis within 7–10 days of the surgery. A comparison group consisted of 100 consecutive patients who underwent bilateral removal of indicated mandibular wisdom teeth and did not receive PRF placement within the lower third molar surgical sites. Results. The incidence of localized osteitis (LO) following removal of 200 lower third molars with simultaneous PRF placement within the extraction site was 1% (2 sites out of 200). The group of patients whose mandibular 3rd molar sockets were not treated with PRF demonstrated a 9.5% (19 sites out of 200) incidence of localized osteitis. The latter group also required 6.5 hours of additional clinical time to manage LO than the study group who received PRF. Conclusions. This retrospective review demonstrated that preventative treatment of localized osteitis can be accomplished using a low cost, autogenous, soluble, biologic material, PRF, that PRF enhanced third-molar socket healing/clot retention and greatly decreased the clinical time required for postoperative management of LO. PMID:23653648

Hoaglin, Donald R.; Lines, Gary K.

2013-01-01

129

Loss of molars early in life develops behavioral lateralization and impairs hippocampus-dependent recognition memory  

PubMed Central

Background Using senescence-accelerated mouse prone 8 (SAMP8), we examined whether reduced mastication from a young age affects hippocampal-dependent cognitive function. We anesthetized male SAMP8 mice at 8 weeks of age and extracted all maxillary molar teeth of half the animals. The other animals were treated similarly, except that molar teeth were not extracted. At 12 and 24 weeks of age, their general behavior and their ability to recognize novel objects were tested using the open-field test (OFT) and the object-recognition test (ORT), respectively. Results The body weight of molarless mice was reduced significantly compared to that of molar-intact mice after the extraction and did not recover to the weight of age-matched molar-intact mice throughout the experimental period. At 12 weeks of age, molarless mice showed significantly greater locomotor activity in the OFT than molar-intact mice. However, the ability of molarless mice to discriminate a novel object in the ORT was impaired compared to that of molar-intact mice. The ability of both molarless and molar-intact SAMP8 mice to recognize objects was impaired at 24 weeks of age. These results suggest that molarless SAMP8 mice develop a deficit of cognitive function earlier than molar-intact SAMP8 mice. Interestingly, both at 12 and 24 weeks of age, molarless mice showed a lateralized preference of object location in the encoding session of the ORT, in which two identical objects were presented. Their lateralized preference of object location was positively correlated with the rightward turning-direction preference, which reached statistical significance at 24 weeks of age. Conclusions Loss of masticatory function in early life causes malnutrition and chronic stress and impairs the ability to recognize novel objects. Hyperactivation and lateralized rotational behavior are commonly observed with dysfunction of the dopaminergic system, therefore, reduced masticatory function may deplete the mesolimbic and mesocorticolimbic dopaminergic systems to impair the cognitive functions of selective attention and recognition memory in the prefrontal cortex and the hippocampus. PMID:24387332

2014-01-01

130

Primary Mandibular First Molar with Single Root and Single Canal: A Case Report of a Rare Morphology  

PubMed Central

Single rooted primary mandibular first molar is a rare developmental anomaly. Literatures reveal that failure of invagination of Hertwig’s epithelial root sheath leads to this unusual root form. Thorough knowledge of root canal morphology and anatomical variations of primary teeth can help a pediatric dentist in successful root canal treatment. Hereby, we describe two cases of primary mandibular first molars with an unusual morphology as a single root called pyramidal molar.

Bahrololoomi, Zahra; Ghafourifard, Roya; Soleimani, Ali Asghar

2014-01-01

131

Cone beam computed tomography findings of ectopic mandibular third molar in the mandibular condyle: report of a case  

PubMed Central

Impaction of third molar is a common developmental abnormality. However, ectopic impaction of the mandibular third molar in condylar region is an extremely rare condition. This report describes a case of impacted tooth in the mandibular condyle without any associated pathologic condition. Also, this report presents the spatial relationship of the impacted mandibular third molar to the surrounding anatomic structures using cone beam computed tomography. PMID:22010071

2011-01-01

132

A clinical and microbiological comparative study of deep carious lesion treatment in deciduous and young permanent molars  

Microsoft Academic Search

The aim of this study was to compare one-visit indirect pulp treatment (IPT), two-visit IPT, and direct complete excavation\\u000a (DCE) of deciduous and young permanent molars with deep carious lesions from clinical and microbiological points of view.\\u000a One hundred thirty-five teeth (83 deciduous molars and 52 young permanent molars) were included in the study. The teeth were\\u000a randomly selected and

Ayse I. Orhan; Firdevs T. Oz; Berrin Ozcelik; Kaan Orhan

2008-01-01

133

Study of O2 (1Delta) production in a glow discharge at large molar flow rates  

Microsoft Academic Search

O2 (1-Delta) production in an electric discharge is presently studied under the 5-10 mmol\\/sec molar flow rate and 10 Torr pressure required by an iodine laser. The production of large flow rates of singlet molecular oxygen and of atomic oxygen is demonstrated, and the possibility of initiating an iodine laser with discharged oxygen is ruled out.

L. Torchin; R. Jegou; H. Brunet

1983-01-01

134

Unerupted lower third molars and their influence on fractures of the mandibular angle and condyle.  

PubMed

Our aim was to assess the influence of the presence and state of impaction of mandibular third molars on the incidence of fractures of the mandibular angle and condyle. We designed a retrospective study of patients who presented for the treatment of mandibular fractures from January 2006 to April 2011. The independent variables were the presence and degree of impaction of lower third molars, and the outcome variables were the incidence of fractures of the mandibular angle and condyle. The information was acquired from hospital records and panoramic radiographs. Personal data included age, sex, mechanism of injuries, and number of fractures of the mandibular angle and condyle. We studied 110 fractures of the mandibular condyle and 80 of the angle. The incidence of fractures of the mandibular angle was higher in the group with incompletely erupted third molars (37/80, p<0.001) and that of condylar fractures was higher in the group without (67/110, p<0.001). An incompletely erupted third molar reduces the risk of condylar fractures and increases the risk of fractures of the mandibular angle. PMID:21764189

Patil, Pavan M

2012-07-01

135

Surgical Removal of Fractured Endodontic Instrument in the Periapex of Mandibular First Molar  

PubMed Central

The purpose of this article is to present the surgical removal of a broken endodontic file from the periapical region of the distal root of a mandibular first molar. The methods of diagnosis and measurement of the distance of the instrument to the adjacent vital structures in the periapical region was done with simple means and in an economical manner. PMID:25214740

Gandevivala, Adil; Parekh, Bandish; Poplai, Gaurav; Sayed, Aliya

2014-01-01

136

Caveats when Analyzing Ultra-high Molar Mass Polymers by SEC  

Technology Transfer Automated Retrieval System (TEKTRAN)

The analysis of ultra-high molar mass (M > 1 million g/mol) polymers via size-exclusion chromatography (SEC) presents a number of non-trivial challenges. Dissolution and full solvation may take days, as is the case for cellulose dissolution in non-complexing non degrading solvents; very low concent...

137

Stress distribution produced by the correction of the mandibular second molar in lingual crossbite.  

PubMed

The purpose of this study was to evaluate the stress distribution produced in the dentoalveolar system by a mandibular posterior crossbite appliance used for the correction of mandibular second molars in lingual version. A photoelastic model was fabricated using a photoelastic material (PL-3) to simulate alvelolar bone and ivory-colored resin teeth. The model was observed anteriorly and posteriorly with a circular polariscope and photographically recorded before and after activation of mandibular posterior crossbite appliances. An uncontrolled tipping and an extrusive force were generated when the traction force was applied on the buccal surface of the mandibular second molar. A controlled tipping and an intrusive force were generated when the traction force was applied on the lingual surface of the mandibular second molar. We concluded that to escape the extrusion and uncontrolled tipping that creates occlusal interferences associated with the correction of mandibular second molars in lingual version, the lingual traction force is more useful than the buccal traction force. PMID:12518954

Yoon, Young-Jooh; Jeong, Won-Jung; Jang, Sung-Ho; Hwang, Gab-Woon; Kim, Kwang-Won

2002-12-01

138

Is Overweight a Risk Factor for Adverse Events during Removal of Impacted Lower Third Molars?  

PubMed Central

Being overweight is recognised as a significant risk factor for several morbidities; however, the experience of the dentistry faculties focusing on this population is still low. The aim of the present study was to determine the occurrence of adverse events during removal of impacted lower third molars in overweight patients. A prospective cohort study was carried out involving overweight patients subjected to surgical removal of impacted lower third molar as part of a line of research on third molar surgery. Predictor variables indicative of the occurrence of adverse events during surgery were classified by their demographic, clinical, radiographic, and surgical aspects. Descriptive and bivariate statistics were computed. In total, 140 patients fulfilled the eligibility criteria, and 280 surgeries were performed. Patients' mean age was 25.1 ± 2.2 years, and the proportion of women to men was 3?:?1. Eight different adverse events during surgery were recorded. These events occurred in approximately 29.3% of cases and were significantly associated with predictor variables (P < 0.05). Excess weight is recognised as a risk factor for the high rate of adverse events in impacted third molar surgery. The study suggests that overweight patients are highly likely to experience morbidities. PMID:25548786

de Carvalho, Ricardo Wathson Feitosa; do Egito Vasconcelos, Belmiro Cavalcanti

2014-01-01

139

Estimation of legal age using calcification stages of third molars in living individuals.  

PubMed

The increased number of adolescents and young adults with unknown or inaccurately given date of birth is a current issue in justice and legal medicine. The objective of this study was to determine the extent to which third molar calcification stages assessed on panoramic X-rays could be useful as additional criteria for forensic age estimation in living individuals, focusing on the legally important ages 17 and 18. In a retrospective multi-center study, the developmental stage of each individual's third molar was analyzed using Demirjian's scale in 2360 cases. Additionally, sex, age and ancestry were assessed. Individuals with the lowest calcification stage of all present molars in stage H were ?18years with a likelihood of ?99.05% in the female (n=388), and ?99.24% in the male (n=482) population. The lowest calcification stage of all present third molars proved to be useful as an additional reliable criterion for the determination of an age ?18years. PMID:25498932

Streckbein, Philipp; Reichert, Isabelle; Verhoff, Marcel A; Bödeker, Rolf-Hasso; Kähling, Christopher; Wilbrand, Jan-Falco; Schaaf, Heidrun; Howaldt, Hans-Peter; May, Andreas

2014-12-01

140

A COMPARISON OF LIME AND ORANGE PECTIN BY HPSGC WITH MOLAR MASS AND VISCOSITY DETECTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pectin was acid extracted from lime albedo by microwave heating under pressure. Extraction times ranged from 1 to 10 minutes. Solubilized pectin was characterized for molar mass (M), rms radius of gyration (Rg) and intrinsic viscosity (IV) by HPSEC with online light scattering and viscosity detect...

141

Evaluation of the accuracy of different molar teeth measurements in assessing sex.  

PubMed

Teeth are considered to be a very useful tissue for sex determination and molars are among the most dimorphic teeth. Even though mesiodistal (MD) and buccolingual (BL) crown diameters are usually employed for sex assessment, alternative measurements like MD and BL cervical diameters as well as crown and cervical diagonal diameters have been developed. This study explores the utility of crown and cervical MD, BL and diagonal measurements of molars in sex assessment when used separately. A total of 254 permanent molars (excluded third molars) from 101 individuals (51 males, 50 females) from the Athens Collection were examined. Stepwise discriminant analysis was used to evaluate the accuracy of each diameter group in assessing sex. It was found that the accuracy ranges from 65.5 to 88.4 %. Cervical diagonal diameters are the most accurate followed by crown diagonal diameters, and crown and cervical MD and BL diameters. Therefore the high classification accuracy of diagonal diameters show that these measurements are more reliable for sex determination than the traditional MD and BL and can be considered a promising method for sex assessment from human teeth. PMID:22926774

Zorba, Eleni; Spiliopoulou, Chara; Moraitis, Konstantinos

2013-03-01

142

A familial case of recurrent hydatidiform molar pregnancies with biparental genomic contribution  

Microsoft Academic Search

Hydatidiform mole is a benign trophoblastic neoplasia characterized by an abnormal development of the embryo and proliferation of placental villi. Using microsatellite markers amplified by the polymerase chain reaction, we have performed a genetic study on eight independent molar tissues occurring in two sisters. Karyotype and genotype data demonstrate a diploid and biparental constitution in seven of the analyzed moles

Mazen N. Helwani; Muhieddine Seoud; Laila Zahed; Ghazi Zaatari; Ali Khalil; Rima Slim

1999-01-01

143

Molar Mass Profiling of Synthetic Polymers by Free-Solution Capillary Electrophoresis of  

E-print Network

Molar Mass Profiling of Synthetic Polymers by Free-Solution Capillary Electrophoresis of DNA of the DNA-polymer conju- gates as a function of the size of the uncharged PEG tail. This provides a profile) (PEG)), based upon single-monomer resolution of DNA-polymer conjugates by free-solution capillary

Barron, Annelise E.

144

How to measure and predict the molar absorption coefficient of a protein  

Microsoft Academic Search

The molar absorption coefficient, E, of a protein is usually based on concentrations measured by dry weight, ni- trogen, or amino acid analysis. The studies reported here suggest that the Edelhoch method is the best method for measuring E for a protein. (This method is described by Gill and von Hippel (1989, Anal Biochem 182:319- 3261 and is based on

C. Nick Pace; Felix Vajdos; Lanette Fee; Gerald Grimsley; Theronica Gray

1995-01-01

145

Solution properties of high-molar-mass hyaluronans: the biopolymer degradation by ascorbate  

Microsoft Academic Search

An accurate molecular characterization, molar mass and size distributions, of 10 hyaluronan (HA) samples was performed by using a multi-angle light scattering detector connected on-line to a size exclusion chromatographic system. The dynamic viscosity ? of the HA solutions was investigated using a rotational viscometer. On monitoring the sample dynamic viscosity for up to 5h, a small however constant increase

Ladislav Šoltés; Katarína Valachová; Raniero Mendichi; Grigorij Kogan; Juergen Arnhold; Peter Gemeiner

2007-01-01

146

Age at first molar emergence in Lufengpithecus lufengensis and its implications for life-history evolution.  

PubMed

The late Miocene hominoid Lufengpithecus from Yunnan Province, China, is crucial for understanding hominoid evolution in Asia. Given that age at first permanent molar emergence is a key life-history trait in primates, the present study determined the age at death of the Lufengpithecus lufengensis juvenile PA868, which was in the process of erupting its first molar. Using a perikymata periodicity of 7-11 days, along with estimation of cusp formation time and the postnatal delay of crown mineralization, perikymata counts obtained from the permanent central incisor and canine germs indicate that the age at death of PA868 was 2.4-4.5 years based on the central incisor germ, and 2.5-4.7 years based on the canine germ. The age at the first molar emergence was actually slightly younger (by about 0.3 years), as demonstrated by tiny wear facets on this tooth, which indicate that gingival emergence had occurred sometime before death. The average age at first molar emergence of Lufengpithecus lufengensis PA868 is estimated to be 3.2-3.3 years, with a range of 2.1-4.4 years. In comparison to extant primates and other fossil hominoids, the life history of Lufengpithecus lufengensis is similar to that of extant great apes and the Miocene hominoids Afropithecus turkanensis and Sivapithecus parvada, as well as Plio-Pleistocene Australopithecus, and different from monkeys, gibbons, and modern humans. PMID:18037472

Zhao, Lingxia; Lu, Qingwu; Zhang, Wending

2008-02-01

147

Comparative trial between the use of amoxicillin and amoxicillin clavulanate in the removal of third molars  

PubMed Central

Objectives: The purpose of this study was to compare the use of amoxicillin (1g) vs amoxicillin and clavulanate (875/125mg) after extraction of retained third molars for prevention of infectious complications. Study Design: The study involved 546 patients attending for removal a retained third molar and divided in to two groups: Group 1 - amoxicillin and clavunate (875/125mg) group (n=257) and Group 2 - amoxicillin (1g) group (n=289). All patients were recalled for investigating the possibility of infection, presence of diarrhea and further analgesic intake. Results: From a total of 546 patients, the frequency of infection was 1.4%, without no statistically differences between the two groups. Group 1 showed statistically higher presence of patients with gastrointestinal complications (p>0.05). In 546 patients, 2.7% of patients reported severe pain that would not relieve with medication. Conclusions: The results of our study show that the use of amoxicillin (1g) and amoxicillin and clavunate (875/125mg) is similar efficacious in preventing infection after retained third molar extraction but amoxicillin and clavunate (875/125mg) produces more gastrointestinal discomfort. Key words:Amoxicillin, clavulanate, third molars, complications. PMID:24880449

Iglesias-Martín, Fernando; García-Perla-García, Alberto; Yañez-Vico, Rosa; Rosa, Elena; Arjona-Gerveno, Esther; González-Padilla, Juan D.; Gutierrez-Pérez, Jose L.

2014-01-01

148

Vienna-Chicago: the cultural transformation of the model system of the un-opposed molar.  

PubMed

The discussion over the roles of genes and environment on the phenotypical specification of organisms has held a central role in science philosophy since the late 19(th) century and has re-emerged in today's debate over genetic determinism and developmental plasticity. In fin-de-siecle Vienna, this debate coincided with a philosophical debate over empiricism/materialism versus idealism/vitalism. Turn-of-the-century Vienna's highly interdisciplinary environment was also the birthplace for the model system of the un-opposed molar. The un-opposed molar system features new tissue formation at the roots of teeth and tooth drift once opposing teeth are lost. The un-opposed molar model system was revived by a group of Viennese scientists who left Vienna during the Nazi period to address Vienna's questions about evolution and heredity and about genes and environment in Chicago's post-WWII scientific exile community. Here we are using the colorful history of the un-opposed molar to investigate the role of culture and method in the scientific evolution of a model system. PMID:17621674

Luan, Xianghong; Diekwisch, Thomas G H

2007-08-01

149

Anatomical Study of C-Shaped Canals in Mandibular Second Molars by Analysis of Computed Tomography  

Microsoft Academic Search

The aim of this study was to investigate the prevalence and configuration of the C-shaped canal using serial axial computed tomography images of the mandibular second molars that had not been restored severely or treated endodontically, and to compare the thickness of the remaining tooth structure from the center of the canal to the outer surface of the deepest groove

Guang-Chun Jin; Seong-Jong Lee; Byoung-Duck Roh

2006-01-01

150

Sensibility and taste alterations after impacted lower third molar extractions. A prospective cohort study  

PubMed Central

Objectives: To determine the incidence, severity and duration of lingual tactile and gustatory function impairments after lower third molar removal. Study Design: Prospective cohort study with intra-subject measures of 16 patients undergoing lower third molar extractions. Sensibility and gustatory functions were evaluated in each subject preoperatively, one week and one month after the extraction, using Semmes-Weinstein monofilaments and 5 different concentrations of NaCl, respectively. Additionally, all patients filled a questionnaire to assess subjective perceptions. Results: Although patients did not perceive any sensibility impairments, a statistically significant decrease was detected when Semmes-Weinstein monofilaments. This alteration was present at one week after the surgical procedure and fully recovered one month after the extraction. There were no variations regarding the gustatory function. Conclusions: Lower third molar removal under local anesthesia may cause light lingual sensibility impairment. Most of these alterations remain undetected to patients. These lingual nerve injuries are present one week after the extraction and recover one month after surgery. The taste seems to remain unaffected after these procedures. Key words:Lingual nerve, third molar, nerve injury, paresthesia, surgical extraction PMID:22322520

Ridaura-Ruiz, Lourdes; Valmaseda-Castellón, Eduard; Berini-Aytés, Leonardo; Gay-Escoda, Cosme

2012-01-01

151

Developmental connections between cranial components and the emergence of the first permanent molar  

Microsoft Academic Search

The age of emergence of the first molar (M1) is a developmental event correlated with many variables of primate life history, such as adult brain size. The evolution of human life history is characterized by the inclusion of child- hood, which takes place between weaning and M1 emergence. Children still depend on adults for nutrition due to their small digestive

Marina L. Sardi; Fernando Ramírez Rozzi

2007-01-01

152

Characterization of Alternan, a high molar mass polysaccharide from Leuconostoc mesenteroides, by FFF-MALS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Native alternan is a high molar mass homopolymer of D-glucose produced by some strains of the bacterium Lueconostoc mesenteroides. It consists of glucose units that alternate their linkages between alpha-(1-6) and alpha-(1-3) between glucosyl units. The glucose units contained in the polysaccharid...

153

Artefacts in Cone Beam CT Mimicking an Extrapalatal Canal of Root-Filled Maxillary Molar  

PubMed Central

Despite the advantages of cone-beam computed tomography (CBCT), the images provided by this diagnostic tool can produce artifacts and compromise accurate diagnostic assessment. This paper describes an endodontic treatment of a maxillary molar where CBCT images suggested the presence of a nonexistent third root canal in the palatal root. An endodontic treatment was performed in a first maxillary molar with palatal canals, and the tooth was restored with a cast metal crown. The patient returned four years later presenting with a discomfort in chewing, which was reduced after occlusal adjustment. CBCT was prescribed to verify additional diagnostic information. Axial scans on coronal, middle, and apical palatal root sections showed images similar to a third root canal. However, sagittal scans demonstrated that these images were artifacts caused by root canal fillings. A careful interpretation of CBCT images in root-filled teeth must be done to avoid mistakes in treatment. PMID:23606995

Camilo, Carla Cristina; Brito-Júnior, Manoel; Faria-e-Silva, André Luis; Quintino, Alex Carvalho; de Paula, Adrianne Freire; Cruz-Filho, Antônio Miranda; Sousa-Neto, Manoel Damião

2013-01-01

154

Mini-implant-borne Pendulum B appliance for maxillary molar distalisation: design and clinical procedure.  

PubMed

A treatment objective of upper molar distalisation may often be required during the correction of a malocclusion. Distalisation is not only indicated for the management of Class II patients, but also for Class III surgery patients who require decompensation in the upper arch if upper incisor retrusion is needed. Unfortunately, most conventional intra-oral devices for non-compliance maxillary molar distalisation experience anchorage loss. A Pendulum type of appliance and a mini-implant-borne distalisation mechanism have been designed which can be inserted at chair-side, without a prior laboratory procedure and immediately after mini-implant placement. For re-activation purposes, a distal screw may be added to the Pendulum B appliance. PMID:25549527

Wilmes, Benedict; Katyal, Vandana; Drescher, Dieter

2014-11-01

155

Sharp Curvature of Premolar Resulting in External Apical Root Resorption of the Neighbouring Molar  

PubMed Central

This case report describes an external apical root resorption resulted from the unusual root morphology of the neighbouring tooth. A 28-year-old female was referred to the department of endodontics with a complaint of intense pain in her maxillary second premolar tooth. The clinical and radiographical evaluation revealed an external apical resorption in the mesial root of the maxillary first molar, which shows close proximity to the severely curved root of the premolar. A successful root canal treatment of the premolar was performed using anticurvature filing method. However, molar tooth received no curative treatment. One-year followup of the apical external resorption did not show any progression. External apical root resorption affecting single permanent tooth may be induced from the pressure exerted during the eruption of the adjacent tooth with unusual root morphology. The preferred approach for the management of such apical resorption cases includes long-term observation and no curative treatment. PMID:22567442

Ulusoy, Özgür ?lke Atasoy

2011-01-01

156

Endodontic treatment of a mandibular first molar with 8 canals: a case report  

PubMed Central

Presented here is a case where 8 canals were located in a mandibular first molar. A patient with continuing pain in mandibular left first molar even after completion of biomechanical preparation was referred by a dentist. Following basic laws of the pulp chamber floor anatomy, 8 canals were located in three steps with 4 canals in each root. In both of the roots, 4 separate canals commenced which joined into two canals and exited as two separate foramina. At 6 mon follow-up visit, the tooth was found to be asymptomatic and revealed normal radiographic periapical area. The case stresses on the fact that understanding the laws of pulp chamber anatomy and complying with them while attempting to locate additional canals can prevent missing canals.

Acharya, Shashi Rashmi; Sharma, Padmaja

2015-01-01

157

Entropy Estimates for Some Silicates at 298{degrees}K from Molar Volumes.  

PubMed

Third law entropies for silicates of Be, Mg, Ca, Zn, Na, and K containing the same anion group, for example, SiO(4) or SiO(3) or AlSi(3)O(8), are found to be linearly related to their molar volumes. The relationship between the molar volume and the entropy of silicates of Fe and Mn, atoms with unfilled d electron subshells, is different from that of other silicates. The linear correlations yield a useful method of estimating the entropies of ortho-, meta-, and framework silicates (feldspars and feld-spathoids). The estimated entropies of pyrope and almandine at 298 degrees K are 47.47 and 68.13 gibbs per mole, respectively. PMID:17837020

Saxena, S K

1976-09-24

158

Degradation of high-molar-mass hyaluronan and characterization of fragments.  

PubMed

A sample of high-molar mass hyaluronan was oxidized by seven oxidative systems involving hydrogen peroxide, cupric chloride, ascorbic acid, and sodium hypochlorite in different concentrations and combinations. The process of the oxidative degradation of hyaluronan was monitored by rotational viscometry, while the fragments produced were investigated by size-exclusion chromatography, matrix-assisted laser desorption ionization-time-of-flight mass spectrometry, and non-isothermal chemiluminometry. The results obtained imply that the degradation of hyaluronan by these oxidative systems, some of which resemble the chemical combinations present in vivo in the inflamed joint, proceeds predominantly via hydroxyl radicals. The hyaluronan fragmentation occurred randomly and produced species with rather narrow and unimodal distribution of molar mass. Oxidative degradation not only reduces the molecular size of hyaluronan but also modifies its component monosaccharides, generating polymer fragments that may have properties substantially different from those of the original macromolecule. PMID:17691842

Soltés, L; Kogan, G; Stankovska, M; Mendichi, R; Rychlý, J; Schiller, J; Gemeiner, P

2007-09-01

159

Morphologic analysis of third-molar maturity by digital orthopantomographic assessment.  

PubMed

Accurate timing of the eruption of first and permanent teeth is an important parameter in forensic odontology to establish the age of dead or live individuals. Determination of adulthood may determine, for example, whether an individual convicted of a crime is sentenced as an adult and incarcerated in a state penal institution or as a juvenile and sent to a juvenile camp. At present, there is a large immigrant population in Italy, and young foreign criminals sometimes have false passports bearing a later birth date, with the aim of evading punishment. In such circumstances, age determination is becoming a significant forensic issue.Late in adolescence, after formation of the premolars and canines, only the third molars continue to develop. According to several studies, although the third molars are the most variable teeth in the dentition, they remain the most reliable biologic indicator available for estimation of age during the middle teens and early twenties.In this study, the authors test the possibilities offered by orthopantomography executed by means of digital technology, with the aim of exploiting the advantages of the computerized digital technique compared with the conventional technique, to determine adult age on the basis of root development of the third molar.Digital radiography is simple to use, quick, and effective, allowing superimposition and enlargement; the images can be electronically stored and transported. In comparison with traditional orthopantomography, the digital technique features greater diagnostic accuracy of some anatomic structures: upper and lower front teeth, root apexes, floor of the nasal fossa and maxillary sinus, nasal septum, mandibular condylus. Moreover, digital orthopantomography suffers less from artifacts.The digital orthopantomographies of 83 Caucasian subjects (43 females and 40 males) aged between 16 and 22 years were analyzed in standard conditions, assessing the degree of maturation of the upper and lower third molars. A standardized computer procedure was used to acquire the x-ray images, recording 3 per plate: the overall orthopantomography and 2 enlargements of optical type of the left and right sides, to reveal the third molars while maintaining unaltered the image resolution.For the analysis, the authors adopted Demirjian's staging system that classifies development of the third molar in 8 stages (A, B, C, D, E, F, G, H) on the basis of morphologic criteria. This has been statistically proved to feature notable precision and high predictive ability.To assess any sex-related variations in mineralization speed, the series was subdivided by gender. The study demonstrated that such differences are more evident under the age of 18 years.Overall, the observation of 245 third molars showed faster development of the upper than the lower third molars, a prevalence of stages D to G in the age range between 16 and 18 years, and a clear predominance of stage H in individuals over 18 years of age. Finally, an intermediate stage between G and H was demonstrated in subjects aged between 17 and 21 years. PMID:19749618

Introna, Francesco; Santoro, Valeria; De Donno, Antonio; Belviso, Maura

2008-03-01

160

Endodontic Retreatment of a Mandibular Second Molar with four Separate Roots: A Case Report  

PubMed Central

Aberrations in the root canal anatomy are a commonly occurring phenomenon. Although the mandibular second molar is commonly a bi-rooted tooth with an uncomplicated endodontic anatomy, variations have to be considered every time endodontic therapy is performed. This case report describes the non-surgical endodontic retreatment performed on a mandibular second molar with four seperate roots and canals. ProTaper Universal rotary nickel-titanium instruments (Dentsply Maillefer, Ballaigues, Switzerland) for treatment and retreatment were used to remove the old gutta percha and to clean and shape all root canals, followed by the complete obturation of root canal system. Post-operative CBCT scan was taken to confirm the quality of the performed treatment. PMID:24783160

Idris, Mohamed; Sakkir, Nasil; KJ, Nandakishore; Kini, Annapurna

2014-01-01

161

Implication of Sphingomyelin/Ceramide Molar Ratio on the Biological Activity of Sphingomyelinase  

PubMed Central

Abstract Sphingolipid signaling plays an important, yet not fully understood, role in diverse aspects of cellular life. Sphingomyelinase is a major enzyme in these signaling pathways, catalyzing hydrolysis of sphingomyelin to ceramide and phosphocholine. To address the related membrane dynamical structural changes and their feedback to enzyme activity, we have studied the effect of enzymatically generated ceramide in situ on the properties of a well-defined lipid model system. We found a gel-phase formation that was about four times faster than ceramide generation due to ceramide-sphingomyelin pairing. The gel-phase formation slowed down when the ceramide molar ratios exceeded those of sphingomyelin and stopped just at the solubility limit of ceramide, due to unfavorable pairwise interactions of ceramide with itself and with monounsaturated phosphatidylcholine. A remarkable correlation to in vitro experiments suggests a regulation of sphingomyelinase activity based on the sphingomyelin/ceramide molar ratio. PMID:20643068

Boulgaropoulos, Beate; Amenitsch, Heinz; Laggner, Peter; Pabst, Georg

2010-01-01

162

Iatrogenic molar borings in 18th and early 19th century Native American dentitions.  

PubMed

Six iatrogenic dental borings were identified in four individuals of a Native American skeletal collection from an 18th and early 19th century Middle Columbia River burial site. The borings, all in maxillary first molars with severe dental attrition and secondary dentin, demonstrate striated walls and associated periapical alveolar lesions. An ethnographic review of the subsistence pattern during the burial period indicates a diet that is consistent in dental attrition with other riverine fisher-hunter-gathers. Histological changes of dental pulp tissue during the process of attrition may result in dental necrosis. Access into the pulp chamber is a technique used to drain necrotic fluid. A common Euro-American therapeutic dental practice of the 18th and 19th centuries for diseases of the pulp was dental extraction. Multiple dental borings indicate that the practice of molar drilling into the pulp chamber was an effective and independent technique used by the Wishram and Wasco people. PMID:15486962

Seidel, John C; Colten, Roger H; Thibodeau, Edward A; Aghajanian, John G

2005-05-01

163

Four-Rooted Mandibular First Molar with an Unusual Developmental Root Fusion Line: A Case Report  

PubMed Central

The paper describes the anatomical variation of four roots in a mandibular permanent first molar diagnosed using multiple angulated preoperative radiographs and its successful nonsurgical endodontic management. Careful observation and exploration of the pulpal floor using a dental operating microscope revealed a peculiar developmental root fusion line on the pulp chamber floor. Based on the above observation, a correlation between this unusual line and the existence of additional roots has been proposed and discussed. PMID:22792498

Kottoor, Jojo; Albuquerque, Denzil Valerian; Velmurugan, Natanasabapathy; Sumitha, Mylswamy

2012-01-01

164

Immunodetection of Osteopontin at Sites of Resorption in the Pulp of Rat Molars  

Microsoft Academic Search

SUMMARY Osteopontin (OPN) has been proposed to act as a substrate for osteoclast ad- hesion during bone resorption. The aim of the present study was to examine the presence and distribution of OPN at sites of resorption in traumatized radicular pulp. The upper first molars of 6-week-old male Sprague-Dawley rats were luxated and then repositioned in the original sockets. The

Yoshihito Shimazu; Antonio Nanci; Takaaki Aoba

165

Excess molar enthalpies for mixtures of supercritical carbon dioxide and water + ethanol solutions  

Microsoft Academic Search

Excess molar enthalpies (H E m) for mixtures of supercritical CO2 and ethanol aqueous solutions were measured at 323.15 K and 7.64 and 15.00 MPa using an isothermal high-pressure flow calorimeter. H E m values obtained at the lower pressure are very exothermic while those obtained at the higher pressure are moderately endothermic. H E m for CO2 +H 2O

Eduardo P; Yolanda S ´ anchez-Vicente; Albertina Caba; Juan A. R. Renuncio

2005-01-01

166

Administration of bisphosphonate (ibandronate) impedes molar tooth movement in rabbits: A radiographic assessment  

PubMed Central

Introduction: Bisphosphonate (Bp)-ibandronate is a pharmacological agent, exhibits antiosteoclastic or antiresorptive activity and used to treat osteolytic or osteopenic disorders. BP-ibandronate may also interfere during orthodontic tooth movement. The aim of this study was to examine the influence of locally administered Bp-ibandronate on experimental tooth movement in rabbits. Materials and Methods: Twenty rabbits were divided into two groups- “10” served as Group-1 (control) and other “10” as Group-2 (experimental). Both groups received nickel-titanium closed coil springs with 100 g force between mandibular molar and incisors. Group-1 animals received 1 ml normal saline and Group-2 animals received ibandronate solution (0.3 mg/kg body weight) locally, mesial to the mandibular molar on the 1st, 7th, and 14th day of the experiment. A total of “40” lateral cephalograms were taken from both groups on the 1st and 21st day using a digital X-ray unit (Siemens X-ray systems, 300 mA Pleomophos analog, 2008, Germany). Individually, each animal's radiograph was traced manually and superimposed. The molar tooth movement was measured with the help of a standard metric scale. Results: The Student's t-test has been done to compare the mean values of Group-1 (4.650 ± 0.363) and Group-2 (2.030 ± 0.291) and the difference was statistically significant (P < 0.001). Conclusion: The retarded molar tooth movement was noticed in local drug administered rabbits, which could be beneficial in orthodontics to control the undesired tooth movement. PMID:25210364

Venkataramana, V.; Kumar, S. Sathesh; Reddy, B. Vishnuvardhan; Cherukuri, A. Sreekanth; Sigamani, K. Raja; Chandrasekhar, G.

2014-01-01

167

Effects of localmelatonin application on post-extraction sockets after third molar surgery. A pilot study  

PubMed Central

Objectives: The purpose of this study was to assess the anti-inflammatory, analgesic and osteogenic early effects of melatonin on post-extraction sockets ofpatients requiring third molars extraction. Study Design: A randomized, triple-blind clinical trial was made using a split-mouth design. Both lower third molars of 10 patients were extracted and 3 mg of local melatonin or placebo were applied. Concentrations of interleukin-6 and nitrotyrosine were determined on samples of the clot from the socket by independent ELISA tests. Radiographic bone density was evaluated by measuring Hounsfield Units in panoramic and cross sections obtained by digital scanner. Statistycal analysis by Kolmogorov-Smirnov test was performed for ELISA data. Bone density was analyzed by Shapiro-Wilk test. Subsequently t test was applied. P<0.05 was considered to be significant. Results: The concentration of interleukin-6 increased with the application of melatonin without statistically significance (361.32 ± 235.22 pg/ml vs 262.58 ± 233.92 pg/ml). Nitrotyrosine concentrations showed values below to the detectability pattern (<0.001 nM) in Optic Density curve. Bone density in panoramic sections at socket after melatonin application showed no significant difference (561.98 ± 105.92 HU vs 598.82 ± 209.03 HU). In cross sections, bone density in the alveolar region showed no significant difference(377.42 ± 125.67 HU vs 347.56 ± 97.02 HU). Conclusions: Within the limitations of this pilot study, no differences with the application of melatonin were found in terms of the concentration of interleukin-6 and bone density in post-extraction socket of retained mandibular third molars. Key words:Melatonin, inflammation, pain, bone density, third molar surgery. PMID:25350595

Fernández-Tresguerres, Isabel; Ortega-Aranegui, Ricardo; López-Quiles, Juan

2014-01-01

168

An Innovative Approach for Management of Vertical Coronal Fracture in Molar: Case Report  

PubMed Central

Unlike anterior teeth, acute exogenous trauma is an infrequent cause of posterior coronal vertical tooth fractures. Endodontic and restorative management of such fractures is a great challenge for the clinician. Newer advancements in adhesive techniques can provide successful intracoronal splinting of such teeth to reinforce the remaining tooth structure. This paper describes the diagnosis and management of a case of complicated vertical coronal fracture in mandibular first molar induced by a traffic accident. PMID:22567453

Kathuria, Ambica; Kavitha, M.; Ravishankar, P.

2012-01-01

169

Prevalence and Bilateral Occurrence of First Permanent Molar Caries in 12-Year-Old Students  

PubMed Central

Background and aims Dental caries is one of the most prevalent chronic diseases in children and DMFT index is the most important quantitative factor for measuring tooth health. The purpose of the present study was to determine prevalence and bilateral occurrence of first permanent molar caries in 12-year-old Iranian students. Materials and methods This cross-sectional study was carried out on 563 twelve-year-old stu-dents (307 boys and 256 girls), randomly selected from private and public schools of Rafsanjan, Iran, in 2006. All students were examined clinically for dental caries using the World Health Organization (WHO) criteria by a specialist on a dental chair in Rafsanjan Dental School. Data was analyzed using chi-square and t-test. Results The mean DMFT score of first permanent molars was 1.9 ± 1.6 (1.83 boys, 1.98 girls) and 31.4% (32.9% boys, 29.7% girls) of the students were caries free. There were no significant differences between boys and girls. Decayed (D) component yielded to be 40.9%, missing (M) 0.35% and filled (F) 6.22%. Maxillary and mandibular first permanent molars had 80.8% and 84% bilateral caries occurrence, respectively. There were no significant differences between the caries prevalence of right and left sides. Conclusion Caries prevalence among 12-year-old students in Rafsanjan, Iran is less than the global standards of WHO and FDI for 2000, but close to the gold standard for 2010. Bilateral caries occurrence in the first permanent molars was concluded to be high in the study population. PMID:23277840

Sadeghi, Mostafa

2007-01-01

170

Electrical Conductance of Fissure Enamel in Recently Erupted Molar Teeth as Related to Caries Status  

Microsoft Academic Search

Pit-and-fissure caries lesions contribute greatly to the caries incidence in permanent molar teeth in children. To date, the diagnosis of occlusal caries is still performed mainly by visual inspection, periodically aided by bite-wing radiography. However, in detecting small occlusal carious lesions, these methods perform inadequately, especially in low caries prevalence populations or individuals. The use of electrical conductance measurements (ECMs)

Y. L. Ie; E. H. A. M. Verdonschot; M. J. M. Schaeken; M. A. van’t Hof

1995-01-01

171

Evaluation of chronological age based on third molar development in the Spanish population  

Microsoft Academic Search

A cross-sectional study was carried out to assess chronological age estimation based on the stages of third lower molar development, following the eight stages (A–H) method of Demirjian et al. The final sample consisted of 1,054 orthopantomograms from Spanish individuals of known chronological age (range 14–21 years) and gender (462 males and 592 females). Results showed a stronger correlation for

José L. Prieto; Elena Barbería; Ricardo Ortega; Concepción Magaña

2005-01-01

172

Measurement and correlation of excess molar enthalpy at various temperatures acetonitrile + diethylamine or s -butylamine mixtures  

Microsoft Academic Search

Summary As a continuation of our studies on excess functions of binary systems containing acetonitrile-amines mixtures, in this work excess molar enthalpy (HmE) of acetonitrile+diethylamine or s-butylamine mixtures have been determined as a function of composition at 288.15, 293.15, 298.15 and 303.15 K at atmospheric pressure using a modified 1455 Parr adiabatic calorimeter. The excess enthalpy data are positive for

R. F. Checoni; A. Z. Francesconi

2005-01-01

173

Bone sialoprotein-induced reparative dentinogenesis in the pulp of rat’s molar  

Microsoft Academic Search

Bone sialoprotein (BSP), an osteogenic protein (OP), mixed with a carrier, was implanted in the pulp of rat first upper molars\\u000a (OP group). Cavities were prepared with dental burs and pulp perforation was carried out by pressure with the tip of a steel\\u000a probe. After 8, 14, and 30 days, the rats were killed and the pulps of the OP

F. Decup; B. Palmier; D. Buch; J. J. Lasfargues; E Salih; M. Goldberg

2000-01-01

174

Mean-square optical anisotropies and molar Kerr constants of cyclic and linear dimethyl siloxanes  

Microsoft Academic Search

Mean-square optical anisotropies, ??2?0, and mean molar Kerr constants, ?mK?0, have been calculated for cyclic dimethyl siloxane oligomers having from n=8 to n=20 skeletal bonds. Stringent criteria were used to select ‘‘cyclic’’ conformations of the equivalent open chains based on the relative orientations and rotational states of the terminal bonds. The values obtained for the cyclic oligomers are compared with

Stephen J. Mumby; Martin S. Beevers

1985-01-01

175

Indications and Risk Factors for Complications of Lower Third Molar Surgery in a Nigerian Teaching Hospital  

PubMed Central

Background: The surgical extraction of impacted third molars is a common oral surgical procedure, and it is often associated with complications such as sensory nerve damage, dry socket, pain, swelling, trismus, infection and hemorrhage. Aim: The aim of this study was to determine the surgical indications and risk factors for complications of third molar surgery at a Nigerian teaching hospital. Materials and Methods: Medical records of patients referred to the Oral Surgery Clinic of our institution for surgical extraction of their impacted mandibular third molars from January 2008 to December 2010 were retrospectively examined. Information on patients’ demography, types of impaction, operative parameters and complications were obtained and analyzed using Statistical Package for Social Sciences (SPSS Version 13), Chicago, IL, USA. A P < 0.0.5 was considered significant. Results: A total of 330 impacted teeth were extracted from 250 patients. Male comprises (104/250 [41.6%]) and female (146/250 [58.4%]). The mesioangular (176/330 [53.4%]) and distoangular (73/330 [22.1%]) impactions were the commonest types. Recurrent pericoronitis (154/330 [46.7%]) was the most common indication for extraction. The complications were delayed healing (19/330 [5.8%]), alveolar, osteitis (9/330 [2.7%]) and injury to alveolar nerve (2/330 [0.6%]). Cigarette smoking (P < 0.001), Oral contraceptives use (P = 0.01), age of the patient (P = 0.03) and the surgeon's experience (P = 0.04) were found to be significantly associated with the development of alveolar osteitis; nerves injuries were significantly associated with the raising of a lingual flap (P < 0.001) and the technique of surgery (P ? 0.001). Conclusion: The age of the patient, cigarette smoking and oral contraceptive use at the time of surgery are some of the factors affecting outcome in third molar surgery. PMID:25506490

Osunde, OD; Saheeb, BD; Bassey, GO

2014-01-01

176

Near-UV molar absorptivities of alachlor, mecroprop-p, pendimethalin, propanil and trifluralin in methanol  

Microsoft Academic Search

An experimental set-up consisting of two parallel absorption cells coupled to a CCD detector was used to determine absolute values of molar absorptivity coefficients ? of five herbicides (alachlor, mecoprop-p, pendimethalin, propanil and trifluralin) in methanol. The absorption spectra were measured using a deuterium lamp at room temperature (298±2K) over the wavelength range 240–340nm, except for pendimethalin and trifluralin where

Eneida Reyes Perez; Stéphane Le Calvé; Philippe Mirabel

2008-01-01

177

Classifying stages of third molar development: crown length as a predictor for the mature root length.  

PubMed

Multiple tooth development staging techniques were reported based on arbitrarily set borderlines between succeeding stages. Anatomic tooth features or predictions of future tooth part dimensions were described to identify the thresholds between the established stages. The need to predict mature tooth dimensions, while the tooth considered is still in development, is a drawback to use this staging technique for dental age estimations. Using the fully mature crown length as a predictor for the future root length could provide a tool for undisputable staging. The aim of this study was first to measure the crown and root length of fully mature third molars and second to investigate whether the crown length could be used as a predictor of the root length, in order to classify the observed root length as a proportion of the future mature root. The crown and root lengths of all present third molars were digitally measured on dental panoramic radiographs of 1,000 subjects. The included subjects were equally distributed in gender, and their age ranged between 22 and 40 years. Two occlusal borders, the cement enamel junction and the root apices, were defined as landmarks for standardized measurements. Regression models with root length as response and crown length as predictor were established and revealed low R (2) and high RMSE values. Due to the small explained variance by the prediction models and the high variation in prediction errors, the observed crown length cannot be used to predict the final root length of a developing third molar. PMID:24801360

Altalie, Salem; Thevissen, Patrick; Willems, Guy

2015-01-01

178

Effects of early unilateral mandibular first molar extraction on condylar and ramal vertical asymmetry  

PubMed Central

Objective: The objective of the following study is to investigate the mandibular vertical asymmetry in a group of patients with early unilateral mandibular first molar extractions. Materials and Methods: Mandibular asymmetry index measurements (condylar, ramal and condylar-plus-ramal) were performed on the panoramic radiographs of a study group including 51 patients (mean age: 18.60 ± 1.11 years) and a control group of 51 patients (mean age: 18.53 ± 1.29 years). Group I included patients with a unilateral mandibular first molar extracted before the age of 12 years. Group II included patients with no extractions and had excellent Class I relationships, no missing teeth and slight or moderate anterior crowding. A paired t-test was used to determine possible statistically significant differences between the sides for the measurements. Student's t-test was used for the comparison of asymmetry index values between the groups and genders. Results: No group showed statistically significant sex-or side-specific differences for posterior vertical height measurements. Condylar asymmetry index and ramal asymmetry index measurements were not statistically different between the groups, while condylar-plus-ramal asymmetry index (CRAI) measurements were statistically different between the groups (P = 0.019). Conclusions: A slight difference for CRAI value was found in patients with early unilateral mandibular first molar extractions. PMID:24966767

Halicioglu, Koray; Celikoglu, Mevlut; Buyuk, Suleyman K.; Sekerci, Ahmet E.; Candirli, Celal

2014-01-01

179

Gross enamel hypoplasia in molars from subadults in a 16th-18th century London graveyard.  

PubMed

Dental Enamel Hypoplasia has long been used as a common nonspecific stress indicator in teeth from archaeological samples. Most researchers report relatively minor linear and pitted hypoplastic defects on tooth crown surfaces. In this work we report a high prevalence and early age of onset of extensive enamel defects in deciduous and permanent molars in the subadults from the post-medieval cemetery of Broadgate, east central London. Analysis of the dentition of all 45 subadults from the cemetery, using both macroscopic and microscopic methods, reveals disturbed cusp patterns and pitted, abnormal and arrested enamel formation. Forty-one individuals from this group (93.2%) showed some evidence of enamel hypoplasia, 28 of them showing moderate or extensive lesions of molars, deciduous or permanent (63.6% of the sample). Scanning Electron Microscope images reveal many molars with grossly deformed cuspal architecture, multiple extra cusps and large areas of exposed Tomes' process pits, where the ameloblasts have abruptly ceased matrix production, well before normal completion. This indented, rough and poorly mineralized surface facilitates both bacterial adhesion and tooth wear, and when such teeth erupt fully into the mouth they are likely to wear and decay rapidly. We suggest that this complex combination of pitted and plane-form lesions, combined with disruption of cusp pattern and the formation of multiple small cusps, should henceforth be identified as "Cuspal Enamel Hypoplasia." PMID:17492667

Ogden, A R; Pinhasi, R; White, W J

2007-07-01

180

Molar mass of silicon highly enriched in 28Si determined by IDMS  

NASA Astrophysics Data System (ADS)

The molar mass of a new silicon crystal material highly enriched in 28Si ('Si28', x(28Si) >99.99%) has been measured for the first time using a combination of a modified isotope dilution mass spectrometry (IDMS) technique and a high resolution multicollector-ICP-mass spectrometer. This work is related to the redetermination of the Avogadro constant NA with an intended relative measurement uncertainty urel(NA) <= 2 × 10-8. The corresponding experimental investigations of the International Avogadro Coordination (IAC) were performed using this novel 'Si28' material. One prerequisite of the redetermination of NA is the determination of the isotopic composition and thus molar mass of 'Si28' with urel(M('Si28')) <= 1 × 10-8. At PTB, a molar mass M('Si28') = 27.976 970 27(23) g mol-1 has been determined with an associated relative uncertainty urel(M('Si28')) = 8.2 × 10-9, opening the opportunity to reach the target uncertainty of NA.

Pramann, Axel; Rienitz, Olaf; Schiel, Detlef; Schlote, Jan; Güttler, Bernd; Valkiers, Staf

2011-04-01

181

Inferior Alveolar Nerve Injury after Mandibular Third Molar Extraction: a Literature Review  

PubMed Central

ABSTRACT Objectives The purpose of this study was to systematically review the comprehensive overview of literature data about injury to the inferior alveolar nerve after lower third molar extraction to discover the prevalence of injury, the risk factors, recovery rates, and alternative methods of treatment. Material and Methods Literature was selected through a search of PubMed electronic databases. Articles from January 2009 to June 2014 were searched. English language articles with a minimum of 6 months patient follow-up and injury analysis by patient’s reporting, radiographic, and neurosensory testing were selected. Results In total, 84 literature sources were reviewed, and 14 of the most relevant articles that are suitable to the criteria were selected. Articles were analyzed on men and women. The influence of lower third molar extraction (especially impacted) on the inferior alveolar nerve was clearly seen. Conclusions The incidence of injury to the inferior alveolar nerve after lower third molar extraction was about 0.35 - 8.4%. The injury of the inferior alveolar nerve can be predicted by various radiological signs. There are few risk factors that may increase the risk of injury to the nerve such as patients over the age of 24 years old, with horizontal impactions, and extraction by trainee surgeons. Recovery is preferable and permanent injury is very rare. PMID:25635208

Juodzbalys, Gintaras

2014-01-01

182

Accuracy of the Dentaport ZX apex locator for working length determination when retreating molar root canals.  

PubMed

The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working length determination during root canal retreatment of mandibular molars. Fifteen extracted mandibular first molars with separate mesial canals and apical foraminae and one distal canal were selected. The mesiobuccal and distal canals were investigated; the length with the file tip at the major diameter was defined as the tooth length (TL). The canals were prepared with ProTaper files to 1 mm short of this and filled with gutta-percha and AH Plus sealer. One week later, the root fillings were removed using ProTaper retreatment files. Tooth length was remeasured and recorded as the retreatment tooth length (RTL). Then electronic measurements were taken at the major (electronic apex locator (EAL) major) and minor (EAL minor) foraminae as suggested by the instrument display. These lengths were compared with RTL and measurements 0.5 and 1 mm short of this distance. For both canals, no significant difference was found between RTL and EAL major, and 0.5 mm short of RTL and EAL minor (P > 0.05). There were significant differences found between all other readings. The Dentaport ZX could not detect the minor foramen accurately but was able to indicate the major foramen in molars undergoing a root canal retreatment procedure. PMID:24697957

Cimilli, Hale; Aydemir, Seda; Arican, Burcin; Mumcu, Gonca; Chandler, Nicholas; Kartal, Nevin

2014-04-01

183

Root and Canal Morphology of Mandibular Second Molar in an Iranian Population by Clearing Method  

PubMed Central

Statement of Problem: The knowledge of the pulp anatomy plays an important role in the success of endodontic treatments. Purpose: The aim of this study was to determine the root and canal morphology of the mandibular second molar teeth in an Iranian population. Material and Methods: One hundred intact human mandibular second molars were collected. The teeth were examined visually and the number of their roots were recorded. The teeth were covered using of lacquer. Access cavities were prepared and the pulp tissue was dissolved by sodium hypochlorite. The apices were covered with the glue and the root canals were injected with the methylene blue and were decalcified with 10% nitric acid, dehydrated with ascending concentrations of alcohol and rendered clear by immersion in methyl salicylate. The following remarks were evaluated: (i) number of root canals per tooth; (ii) number of canals per root; (iii) canal configuration in each root. Results: Of 100 examined teeth; 6% had one root, 89% had two roots, 2% had three roots and 3% had C-shaped roots. The teeth were classified based on the number of canals: 3 % had single canal, 6 % two canals, 54% three canals, 34% four canals, whilst 3 % had C-shaped roots. Based on the Vertucci classification, the most prevalent canal configuration in the mesial root was type II and in the distal root was type I. Conclusion : Iranian mandibular second molar teeth exhibit features which are similar to the average Jordanian, Caucasian and Burmese root and canal morphology. PMID:24724124

Zare Jahromi, M; Jafari Golestan, F; Mashhadi Esmaeil, M; MoouaviZahed, SH; Sarami, M

2013-01-01

184

Impacted lower third molars: Can preoperative salivary pH influence postoperative pain?  

PubMed Central

Aim The literature focuses little attention on factors that influence third molar post extraction pain (PEP). One factor that may play a role in PEP is saliva. We undertook a study in patients subjected to third molar extraction with the aim of assessing the influence of salivary pH on PEP. Materials and Methods: Thirty-one healthy patients with one impacted inferior lower third molar with mean age of 21.02 ± 2.05 years, underwent surgery for similar impactions. The process of pH measuring was carried out without delay after saliva collection, with a combination electrode connected to a PHM 62 pH meter. Pain assessment was done at 4, 8, 12, 18 and 24 hours on the first day. The scale ranged from 0 to 10 in which 0 and 10 denoted ‘no pain’ and ‘maximum pain,’ respectively. Results: The multivariate analysis suggests that the factors that influence pain are patients’ sex (B = - 0.466) and the saliva pH (B = - 1.093). According to the findings of our study, PEP intensity is assumed to have a reverse correlation with salivary pH and is also assumed to be greater in females. Conclusion: Due to the fact that no previous study has indicated such findings so far, further studies are needed to assess the importance of preoperative pH value and its clinical significance on the level of PEP. PMID:22442582

Jafari, Seyed Mehdi; Motamedi, Mohammad Hosein Kalantar; Jafari, Mehrdad; Tabeshfar, Shervin; Jafari, Mehryar; Naghizadeh, Mohammad Mehdi

2010-01-01

185

Does the Relationship between Retained Mandibular Third Molar and Mandibular Angle Fracture Exist? An Assessment of Three Possible Causes  

PubMed Central

The objective of this study is to discuss problems associated with dental retention through three clinical cases of mandible fractures related to the presence of retained lower third molars, emphasizing the possibility of mandible fractures resulting from this or from the extraction procedure. The three evaluated patients had a fracture in the mandible angle. The third molars were present in all the cases, as was the relationship of the fracture with the teeth. After evaluating the three cases and reviewing literature, it is believed that the presence of the retained lower third molars and the surgical procedures for their extraction increase the risk of mandible angle fractures. PMID:23997857

Duarte, Bruno G.; Assis, Diogo; Ribeiro-Júnior, Paulo; Gonçales, Eduardo Sanches

2012-01-01

186

Diagnostic CBCT in Dentigerous Cyst with Ectopic Third Molar in the Maxillary Sinus-A Case Report.  

PubMed

Dentigerous cyst is the second most common odontogenic cyst after radicular cyst. This report describes a case of a dentigerous cyst associated with an impacted maxillary third molar. Patient presented with foul smelling discharge through nose and oral cavity. Cone beam computed tomography revealed maxillary third molar displaced to lateral wall of the nose and a unilocular radiolucency obliterating the entire maxillary sinus. A provisional diagnosis of infected dentigerous cyst was made. The cyst was enucleated along with removal of third molar. Histopathological examination confirmed the diagnosis of dentigerous cyst. The patient recovery was uneventful. PMID:25121067

N S, Mamatha; Krishnamoorthy, Bhuvana; J K, Savitha; Bhai, Pankaja

2014-06-01

187

Comparative Evaluation of Vital Parameters During Third Molar Surgery Under Local Anaesthesia with and without Sedative Agents  

PubMed Central

Aims: To compare vital parameters; operator’s comfort; and patient’s satisfaction during impacted third molar removal under local anaesthesia, with or without sedative agents. Materials and Methods: Ninety patients undergoing elective third molar surgery were randomly divided into three groups of 30 each: Group A received propofol along with local anaesthesia; Group B received midazolam along with local anaesthesia and Group C received local anaesthesia alone. After the local anaesthesia, with or without sedative agents, the impacted third molars were removed in Operation Theater. Results: Group A clearly showed advantages over Group B & C on all the parameters that we have selected. Conclusion: Even though the cost of propofol is high, suitable operating conditions, faster onset of sedation, rapid recovery, and minimal side effects support the use of this drug for conscious sedation for third molar surgery.

Kshisagar, Rajesh A; Dhuvad, Mukesh M

2014-01-01

188

Considerations of mandibular angle fractures during and after surgery for removal of third molars: a review of the literature  

Microsoft Academic Search

Background  Angle fractures are quite common considering that the angle of the mandible forms an area of lower resistance which contains\\u000a a thicker upper border, a thin basilar bone, and the presence of an impacted mandibular third molar. Common complications\\u000a of mandibular third molar surgery include alveolar osteitis (dry socket), secondary infection, nerve dysfunction, and hemorrhage.\\u000a Reports of mandibular fracture during

Bruno Ramos Chrcanovic; Antônio Luís Neto Custódio

2010-01-01

189

Interglobular dentine in first and third molars: Relation to hours of sunshine during growth in two archeological populations from England  

Microsoft Academic Search

Summary  Thin ground sections of first molars (M1), third molars (M3), and second premolars (P2) were scanned by light microscopy for\\u000a relative amounts of interglobular dentine (IGD) in the top half of the crown. Two well-dated cemetery series of English provenance\\u000a were sampled: the Saint Bride's Church collection (SB) from eighteenth century London, for which the sex, age, and calendar\\u000a year

Francis Ivanhoe

1982-01-01

190

Compositional dependence of molar absorptivities of near-infrared OH and H 2O bands in rhyolitic to basaltic glasses  

Microsoft Academic Search

Molar absorption coefficients (molar absorptivities) of the near infrared combination bands at 4500 and 5200 cm?1 assigned to OH groups and H2O molecules, respectively, were determined for glasses of dacitic, andesitic and basaltic compositions. Total water contents (range 1.5–6.3 wt.%) of the samples used in the calibration were determined by pyrolysis and subsequent Karl–Fischer Titration. Different combinations of baseline types

Susanne Ohlhorst; Harald Behrens; François Holtz

2001-01-01

191

Changing the root morphology in a case of periodontal impairment at a maxillary molar used as a sustaining tooth.  

PubMed

Research evolution regarding dental research determines the increase of patient's desire to preserve their dentition for a long time. The loss of a molar tooth as the last teeth present on the dental arch, raises issues regarding how the prosthesis should be placed, still patients are usually reluctant to use as last resort the prosthetic solution. This article describes the technique of root amputation to save a maxillary molar used as bridge abutments. PMID:25329127

D?guci, Constantin; D?guci, Lumini?a; B?t?iosu, Marilena; Popescu, Mihai Raul; Bunget, Adina; M?rg?rit, Ruxandra; Andrei, Oana Cella; Dumitrache, Adina; Vasile, Nicolae; Sfeatcu, Ruxandra

2014-01-01

192

Unique inhibitory cascade pattern of molars in canids contributing to their potential to evolutionary plasticity of diet  

PubMed Central

Developmental origins that guide the evolution of dental morphology and dental formulae are fundamental subjects in mammalian evolution. In a previous study, a developmental model termed the inhibitory cascade model was established. This model could explain variations in relative molar sizes and loss of the lower third molars, which sometimes reflect diet, in murine rodents and other mammals. Here, I investigated the pattern of relative molar sizes (inhibitory cascade pattern) in canids, a taxon exhibiting a wide range of dietary habits. I found that interspecific variation in canid molars suggests a unique inhibitory cascade pattern that differs from that in murine rodents and other previously reported mammals, and that this variation reflects dietary habits. This unique variability in molars was also observed in individual variation in canid species. According to these observations, canid species have greater variability in the relative sizes of first molars (carnassials), which are functionally important for dietary adaptation in the Carnivora. In conclusion, an inhibitory cascade that differs from that in murine rodents and other mammals may have contributed to diverse dietary patterns and to their parallel evolution in canids. PMID:23467478

Asahara, Masakazu

2013-01-01

193

Comparative studies between mice molars and incisors are required to draw an overview of enamel structural complexity  

PubMed Central

In the field of dentistry, the murine incisor has long been considered as an outstanding model to study amelogenesis. However, it clearly appears that enamel from wild type mouse incisors and molars presents several structural differences. In incisor, exclusively radial enamel is observed. In molars, enamel displays a high level of complexity since the inner part is lamellar whereas the outer enamel shows radial and tangential structures. Recently, the serotonin 2B receptor (5-HT2BR) was shown to be involved in ameloblast function and enamel mineralization. The incisors from 5HT2BR knockout (KO) mice exhibit mineralization defects mostly in the outer maturation zone and porous matrix network in the inner zone. In the molars, the mutation affects both secretory and maturation stages of amelogenesis since pronounced alterations concern overall enamel structures. Molars from 5HT2BR KO mice display reduction in enamel thickness, alterations of inner enamel architecture including defects in Hunter-Schreger Bands arrangements, and altered maturation of the outer radial enamel. Differences of enamel structure were also observed between incisor and molar from other KO mice depleted for genes encoding enamel extracellular matrix proteins. Thus, upon mutation, enamel analysis based exclusively on incisor defects would be biased. In view of the functional relationship between enamel structure and tooth morphogenesis, identification of molecular actors involved in amelogenesis requires comparative studies between mice molars and incisors. PMID:25285079

Goldberg, Michel; Kellermann, O.; Dimitrova-Nakov, S.; Harichane, Y.; Baudry, A.

2014-01-01

194

Construction of a cDNA library for miniature pig mandibular deciduous molars  

PubMed Central

Background The miniature pig provides an excellent experimental model for tooth morphogenesis because its diphyodont and heterodont dentition resembles that of humans. However, little information is available on the process of tooth development or the exact molecular mechanisms controlling tooth development in miniature pigs or humans. Thus, the analysis of gene expression related to each stage of tooth development is very important. Results In our study, after serial sections were made, the development of the crown of the miniature pigs’ mandibular deciduous molar could be divided into five main phases: dental lamina stage (E33-E35), bud stage (E35-E40), cap stage (E40-E50), early bell stage (E50-E60), and late bell stage (E60-E65). Total RNA was isolated from the tooth germ of miniature pig embryos at E35, E45, E50, and E60, and a cDNA library was constructed. Then, we identified cDNA sequences on a large scale screen for cDNA profiles in the developing mandibular deciduous molars (E35, E45, E50, and E60) of miniature pigs using Illumina Solexa deep sequencing. Microarray assay was used to detect the expression of genes. Lastly, through Unigene sequence analysis and cDNA expression pattern analysis at E45 and E60, we found that 12 up-regulated and 15 down-regulated genes during the four periods are highly conserved genes homologous with known Homo sapiens genes. Furthermore, there were 6 down-regulated and 2 up-regulated genes in the miniature pig that were highly homologous to Homo sapiens genes compared with those in the mouse. Conclusion Our results not only identify the specific transcriptome and cDNA profile in developing mandibular deciduous molars of the miniature pig, but also provide useful information for investigating the molecular mechanism of tooth development in the miniature pig. PMID:24750690

2014-01-01

195

Treatment outcome and efficacy of an aligner technique – regarding incisor torque, premolar derotation and molar distalization  

PubMed Central

Background The aim of this study was to investigate the efficacy of orthodontic treatment using the Invisalign® system. Particularly, we analyzed the influence of auxiliaries (Attachment/Power Ridge) as well as the staging (movement per aligner) on treatment efficacy. Methods We reviewed the tooth movements of 30 consecutive patients who required orthodontic treatment with Invisalign®. In all patients, one of the following tooth movements was performed: (1) Incisor Torque >10°, (2) Premolar derotation >10° (3) Molar distalization >1.5 mm. The groups (1)-(3) were subdivided: in the first subgroup (a) the movements were supported with the use of an attachment, while in the subgroup (b) no auxiliaries were used (except incisor torque, in which Power Ridges were used). All tooth movements were performed in a split-mouth design. To analyze the clinical efficacy, pre-treatment and final plaster cast models were laser-scanned and the achieved tooth movement was determined by way of a surface/surface matching algorithm. The results were compared with the amount of tooth movement predicted by ClinCheck®. Results The overall mean efficacy was 59% (SD?=?0.2). The mean accuracy for upper incisor torque was 42% (SD?=?0.2). Premolar derotation showed the lowest accuracy with approximately 40% (SD?=?0.3). Distalization of an upper molar was the most effective movement, with efficacy approximately 87% (SD?=?0.2). Conclusion Incisor torque, premolar derotation and molar distalization can be performed using Invisalign® aligners. The staging (movement/aligner) and the total amount of planned movement have an significant impact on treatment efficacy. PMID:24923279

2014-01-01

196

Molar mass characterization of sodium carboxymethyl cellulose by SEC-MALLS.  

PubMed

Two series of sodium carboxymethyl celluloses (NaCMCs) derived from microcrystalline cellulose (Avicel samples) and cotton linters (BWL samples) with average degrees of substitution (DS) ranging from DS=0.45 to DS=1.55 were characterized by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALLS) in 100 mmol/L aqueous ammonium acetate (NH4OAc) as vaporizable eluent system. The application of vaporizable NH4OAc allows future use of the eluent system in two-dimensional separations employing evaporative light scattering detection (ELSD). The losses of samples during filtration and during the chromatographic experiment were determined. The scaling exponent as of the relation [Formula: see text] was approx. 0.61, showing that NaCMCs exhibit an expanded coil conformation in solution. No systematic dependencies of as on DS were observed. The dependences of molar mass on SEC-elution volume for samples of different DS can be well described by a common calibration curve, which is of advantage, as it allows the determination of molar masses of unknown samples by using the same calibration curve, irrespective of the DS of the NaCMC sample. Since no commercial NaCMC standards are available, correction factors were determined allowing converting a pullulan based calibration curve into a NaCMC calibration using the broad calibration approach. The weight average molar masses derived using the so established calibration curve closely agree with the ones determined by light scattering, proving the accuracy of the correction factors determined. PMID:23618306

Shakun, Maryia; Maier, Helena; Heinze, Thomas; Kilz, Peter; Radke, Wolfgang

2013-06-01

197

Function of pretribosphenic and tribosphenic mammalian molars inferred from 3D animation.  

PubMed

Appearance of the tribosphenic molar in the Late Jurassic (160 Ma) is a crucial innovation for food processing in mammalian evolution. This molar type is characterized by a protocone, a talonid basin and a two-phased chewing cycle, all of which are apomorphic. In this functional study on the teeth of Late Jurassic Dryolestes leiriensis and the living marsupial Monodelphis domestica, we demonstrate that pretribosphenic and tribosphenic molars show fundamental differences of food reduction strategies, representing a shift in dental function during the transition of tribosphenic mammals. By using the Occlusal Fingerprint Analyser (OFA), we simulated the chewing motions of the pretribosphenic Dryolestes that represents an evolutionary precursor condition to such tribosphenic mammals as Monodelphis. Animation of chewing path and detection of collisional contacts between virtual models of teeth suggests that Dryolestes differs from the classical two-phased chewing movement of tribosphenidans, due to the narrowing of the interdental space in cervical (crown-root transition) direction, the inclination angle of the hypoflexid groove, and the unicuspid talonid. The pretribosphenic chewing cycle is equivalent to phase I of the tribosphenic chewing cycle, but the former lacks phase II of the tribosphenic chewing. The new approach can analyze the chewing cycle of the jaw by using polygonal 3D models of tooth surfaces, in a way that is complementary to the electromyography and strain gauge studies of muscle function of living animals. The technique allows alignment and scaling of isolated fossil teeth and utilizes the wear facet orientation and striation of the teeth to reconstruct the chewing path of extinct mammals. PMID:25091547

Schultz, Julia A; Martin, Thomas

2014-10-01

198

Absolute silicon molar mass measurements, the Avogadro constant and the redefinition of the kilogram  

NASA Astrophysics Data System (ADS)

The results of an absolute silicon molar mass determination of two independent sets of samples from the highly 28Si-enriched crystal (AVO28) produced by the International Avogadro Coordination are presented and compared with results published by the Physikalisch-Technische Bundesanstalt (PTB, Germany), the National Research Council (NRC, Canada) and the National Metrology Institute of Japan (NMIJ, Japan). This study developed and describes significant changes to the published protocols for producing absolute silicon isotope ratios. The measurements were made at very high resolution on a multi-collector inductively coupled plasma mass spectrometer using tetramethylammonium hydroxide (TMAH) to dissolve and dilute all samples. The various changes in the measurement protocol and the use of TMAH resulted in significant improvements to the silicon isotope ratio precision over previously reported measurements and in particular, the robustness of the 29Si/30Si ratio of the AVO28 material. These new results suggest that a limited isotopic variability is present in the AVO28 material. The presence of this variability is at present singular and therefore its significance is not well understood. Fortunately, its magnitude is small enough so as to have an insignificant effect on the overall uncertainty of an Avogadro constant derived from the average molar mass of all four AVO28 silicon samples measured in this study. The NIST results confirm the AVO28 molar mass values reported by PTB and NMIJ and confirm that the virtual element-isotope dilution mass spectrometry approach to calibrated absolute isotope ratio measurements developed by PTB is capable of very high precision as well as accuracy. The Avogadro constant NA and derived Planck constant h based on these measurements, together with their associated standard uncertainties, are 6.02214076(19) × 1023 mol-1 and 6.62607017(21) × 10-34 Js, respectively.

Vocke, R. D., Jr.; Rabb, S. A.; Turk, G. C.

2014-10-01

199

Microcomputed Tomography Analysis of Mesiobuccal Orifices and Major Apical Foramen in First Maxillary Molars  

PubMed Central

Objective: Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots. Materials and Methods: Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed. Results: The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex. Conclusions: Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex. Clinical Relevance: These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system. PMID:22905069

Spagnuolo, Gianrico; Ametrano, Gianluca; D’Antò, Vincenzo; Formisano, Anna; Simeone, Michele; Riccitiello, Francesco; Amato, Massimo; Rengo, Sandro

2012-01-01

200

Enamel thickness variation of deciduous first and second upper molars in modern humans and Neanderthals.  

PubMed

Enamel thickness and dental tissue proportions have been recognized as effective taxonomic discriminators between Neanderthal and modern humans teeth. However, most of the research on this topic focused on permanent teeth, and little information is available for the deciduous dentition. Moreover, although worn teeth are more frequently found than unworn teeth, published data for worn teeth are scarce and methods for the assessment of their enamel thickness need to be developed. Here, we addressed this issue by studying the 2D average enamel thickness (AET) and 2D relative enamel thickness (RET) of Neanderthal and modern humans unworn to moderately worn upper first deciduous molars (dm(1)s) and upper second deciduous molars (dm(2)s). In particular, we used 3D ?CT data to investigate the mesial section for dm(1)s and both mesial and buccal sections for dm(2)s. Our results confirmed previous findings of an Neanderthal derived condition of thin enamel, and thinner enamel in dm(1)s than dm(2)s in both Neanderthal and modern humans. We demonstrated that the Neanderthal 2D RET indices are significantly lower than those of modern humans at similar wear stages in both dm(1)s and dm(2)s (p < 0.05). The discriminant analysis showed that using 2D RET from dm(1) and dm(2) sections at different wear stages up to 93% of the individuals are correctly classified. Moreover, we showed that the dm(2) buccal sections, although non-conventionally used, might have an advantage on mesial sections since they distinguish as well as mesial sections but tend to be less worn. Therefore, the 2D analysis of enamel thickness is suggested as a means for taxonomic discrimination between modern humans and Neanderthal unworn to moderately worn upper deciduous molars. PMID:25282273

Fornai, Cinzia; Benazzi, Stefano; Svoboda, Ji?í; Pap, Ildikó; Harvati, Katerina; Weber, Gerhard W

2014-11-01

201

What constitutes a clinically important pain reduction in patients after third molar surgery?  

PubMed Central

BACKGROUND: For patients with surgical third molar removal, it is unknown what constitutes a clinically important change in patients’ visual analogue scale (VAS) reports of pain intensity. OBJECTIVES: To determine what constitutes a clinically important change in pain intensity on a VAS following surgical removal of the third molar. METHODS: The study population consisted of patients participating in three randomized trials. Patients were asked to rate their pain three times per day over a period of seven days on a 100 mm VAS after surgical removal of the third molar. Global Perceived Effect was measured on day 1 and day 7 and was used as the external criterion for assessing clinically important pain reduction. Global Perceived Effect scores of 6 (‘much improved’) or higher were classified as clinically ‘successful’, and scores of 5 (‘slightly improved’) or below were classified as clinically ‘unsuccessful’. For each trial, the mean absolute and relative changes in VAS scores were calculated for both ‘successful’ and ‘unsuccessful’ treatments. Sensitivity and specificity analyses were performed. RESULTS: The patients who reported ‘successful’ pain reduction showed a relative pain reduction of ?69% and an absolute pain reduction >2.5 cm on the VAS, whereas patients who classified their pain reduction as ‘unsuccessful’ had a relative pain reduction of ?18.5% and an absolute pain reduction <0.5 cm on the VAS. Furthermore, sensitivity and specificity analyses showed that a cut-off point of ?50% relative pain reduction exhibited the best balance of sensitivity and specificity. CONCLUSION: Relative pain reduction of ?50% and an absolute pain reduction of ?2.5 cm on the VAS were most accurate in predicting a successful pain reduction after a given treatment. PMID:23957018

Martin, Wilhelmus JJM; Ashton-James, CE; Skorpil, NE; Heymans, MW; Forouzanfar, T

2013-01-01

202

Note: Nonpolar solute partial molar volume response to attractive interactions with water.  

PubMed

The impact of attractive interactions on the partial molar volumes of methane-like solutes in water is characterized using molecular simulations. Attractions account for a significant 20% volume drop between a repulsive Weeks-Chandler-Andersen and full Lennard-Jones description of methane interactions. The response of the volume to interaction perturbations is characterized by linear fits to our simulations and a rigorous statistical thermodynamic expression for the derivative of the volume to increasing attractions. While a weak non-linear response is observed, an average effective slope accurately captures the volume decrease. This response, however, is anticipated to become more non-linear with increasing solute size. PMID:24410241

Williams, Steven M; Ashbaugh, Henry S

2014-01-01

203

Endodontic treatment of a mandibular first molar with three mesial canals and broken instrument removal.  

PubMed

To succeed in any dental procedure, the clinician's awareness of the patient's dental anatomy and its variations is crucial. In endodontic therapy, obtaining full information about the root canals' variations can affect the outcome substantially. This case report presents the endodontic treatment of a mandibular first molar exhibiting three mesial root canals with 4 mm of a separated K-file in the coronal third of the mesiolingual canal on an 18-year-old female patient. This case demonstrates the importance of locating additional canals in any roots undergoing endodontic treatment and how the clinician's awareness of aberrant internal anatomy may change the treatment results. PMID:20377564

Faramarzi, Farhad; Fakhri, Hamidreza; Fakri, Hamidreza; Javaheri, Homan H

2010-04-01

204

Fixed maxillary and mandibular zirconia implant frameworks milled with anatomically contoured molars: A clinical report.  

PubMed

Retrospective studies on restoring the patients with complete edentulism have reported a variety of complications, including the excessive wear and fracture of the acrylic resin teeth. Approaches to slow the process of wear include the use of porcelain teeth or altering the occlusal surface of acrylic resin teeth with amalgam or gold. Two 1-piece fixed zirconia implant frameworks masked with gingival porcelain and stained anatomically contoured first and second molars and individual ceramic crowns were used to restore both arches to optimum function and esthetics. This clinical report describes the steps for one method of providing the fixed prosthetic needs of the patients who is edentulous. PMID:25258262

Al-Mazedi, Mohammad; Razzoog, Michael E; Yaman, Peter

2014-11-01

205

The usefulness of Belgian formulae in third molar-based age assessment of Indians.  

PubMed

The third molars are one of few useful predictors for assessing the degree of maturity in adolescence and young adulthood. It has application in age estimation in the age group of 14-23 years, in general, and in juvenile/adult status prediction, in particular. Using a 10-stage grading of third molars, Gunst et al. developed regression formulae on a large sample of Belgians (n=2513) for estimating age. Their research has been recommended as a 'reference study' in age estimation guidelines. The present study has ventured to determine if estimating age in Indians using the Belgian formulae produced results comparable to those reported in the Belgian study; in addition, this study attempts to determine if the same formulae predicted juvenile/adult status (age molars. In total, 916 teeth were assessed using the same 10-stage grading. Age in each OPG was estimated by applying the relevant Belgian regression formulae (regression formulae are available for one, two, three and four third molars). To determine if the formulae produced age estimates comparable to those in the Belgian study, the percentage of Indian subjects whose actual age fell within the 68% confidence interval (CI) (calculated from the ± 1 S.D. value available for each Belgian formula) was ascertained. If ? 68% of Indian subjects' age fell inside this interval, it indicates that the Belgian formulae are applicable in Indians. To assess the suitability of the Belgian formulae in predicting juvenile/adult status in Indians, the accuracy of the age estimation per se was not considered, rather, the number of correct

Bhowmik, Biyas; Acharya, Ashith B; Naikmasur, Venkatesh G

2013-03-10

206

Infinite dilution diffusion coefficients of [Bmim]-based ionic liquids in water and its molar conductivities  

Microsoft Academic Search

In this work, we presented new experimental data of diffusion coefficients of four [Bmim (1-butyl-3-methylimidazolium)]-based ionic liquids in water at infinite dilution for temperatures ranging from 303.2 to 323.2K using Taylor dispersion technique. The investigated ILs were [Bmim][BF4 (tetrafluoroborate)], [Bmim][MeSO4 (methylsulfate)], [Bmim][PF6 (hexafluorophosphate)], and [Bmim][CF3SO3 (trifluoromethanesulfonate)]. The molar conductivities of these ionic liquids were also measured and the infinite dilution

Chun-Li Wong; Allan N. Soriano; Meng-Hui Li

2009-01-01

207

Note: Nonpolar solute partial molar volume response to attractive interactions with water  

SciTech Connect

The impact of attractive interactions on the partial molar volumes of methane-like solutes in water is characterized using molecular simulations. Attractions account for a significant 20% volume drop between a repulsive Weeks-Chandler-Andersen and full Lennard-Jones description of methane interactions. The response of the volume to interaction perturbations is characterized by linear fits to our simulations and a rigorous statistical thermodynamic expression for the derivative of the volume to increasing attractions. While a weak non-linear response is observed, an average effective slope accurately captures the volume decrease. This response, however, is anticipated to become more non-linear with increasing solute size.

Williams, Steven M.; Ashbaugh, Henry S., E-mail: hanka@tulane.edu [Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118 (United States)

2014-01-07

208

Effect of Erythrina mulungu on anxiety during extraction of third molars  

PubMed Central

Objectives: The aim of the present study was to evaluate the effect of Erythrina mulungu on the control of dental anxiety in patients who had under gone bilateral extraction of asymptomatic, impacted mandibular third molars. Material and Methods: In a randomized, double-blind, crossover study, 30 healthy volunteers (5 men and 25 women, over 18 years of age), received either 500mg of E.mulungu (Mulungu Matusa®) or 500 mg of placebo, p.o., one hour before surgical procedure. The level ofanxiety was assessed through questionnaire sand physical parameters, such as blood pressure, heart rate andoxygen saturation. Data were analyzed by Chi-square test, ANOVA (Tukey test) and Friedman with significance level of 5%. Results: A higher preference (Chi-square, p = 0.0062) for E. mulungu was observed for both genders. Volunteers with higher anxiety levels tended to to prefer E. mulungu. No statistically significant differences were verified in blood pressure (one-way ANOVA, p = 0.1259), heart rate (Friedman, p> 0.05) and oxygen saturation (Friedman, p = 0.7664) among periods and types of treatments. Conclusions: E. mulungu showed an anxiolytic effect without significant changes in physiological parameters. It could be considered as an alternative to control the anxiety in adult patients undergoing mandibular thirdmolars surgery. Key words:Anxiety, Erythrina mulungu, third molar, oral surgery. PMID:24880443

Silveira-Souto, Maria L.; São-Mateus, Carla R.; Groppo, Francisco C.

2014-01-01

209

In Search of a Better Option: Dexamethasone Versus Methylprednisolone in Third Molar Impaction Surgery  

PubMed Central

Background: Post-surgical complications like pain, swelling, impaired function cause transient morbidity for the patients leading to refrainment of the treatment. Various preemptive drugs are prescribed to prevent patients from such unpleasant situations. Both dexamethasone and methyl prednisolone can be used for this purpose in surgery of third molar impactions. Materials and Methods: This was a split-mouth study consisting 25 patients having Pell and Gregory’s Class II position B bilateral impactions. About 8 mg dexamethasone and 40 mg methyl prednisolone were prescribed randomly 1 hour prior to the surgery. Pain, swelling and trismus were noted on 1st, 2nd, 3rd and 7th day following surgery. Wilcoxon test was used to assess the significance between the parameters. Results: Reduction in swelling and trismus was found to be significantly more with dexamethasone than methyl prednisolone. However, no statistical significant difference was found in post-operative pain. Conclusion: Dexamethasone can be used as a potent preemptive drug for controlling post-operative complications in the removal of third molar impactions.

Darawade, Dattatraya A; Kumar, Santosh; Mehta, Rupal; Sharma, Anant Raghav; Reddy, G Sharaschandra

2014-01-01

210

Expression of Nfic during root formation in first mandibular molar of rat.  

PubMed

The transcription factor Nfic is a key regulator during tooth development. Nfic deficient mice exhibit short and abnormal molar roots and severely deformed incisors. Dental epithelial cells, known as Hertwig's epithelial root sheath (HERS), participate in root formation. However, whether Nfic is involved in HERS-mesenchyme interaction remains unclear. In this study, the detail temporal and spatial expression pattern of Nfic during rat molar development was examined using immunohistochemistry and in situ hybridization. Nfic was detected in ameloblasts, dental follicle cells (DFCs) and dental papilla cells (DPCs), especially the DPCs close to dentin, from postnatal day 5 to day 16. Nfic expression in DPCs, DFCs and HERS cells was also examined by western blot and RT-PCR. Nfic was detected in DPCs and DFCs, but not in HERS cells. Co-culture experiment further indicated that Nfic mRNA expression in DPCs was elevated by the presence of HERS cells. Our results revealed that Nfic could be a marker gene for root odontoblasts differentiation initiation and its expression might be regulated through epithelial-mesenchymal interaction. PMID:25074584

Chen, Xiang; Chen, Guoqing; Feng, Lian; Jiang, Zongting; Guo, Weihua; Yu, Mei; Tian, Weidong

2014-12-01

211

Reliability of Third Molar Development for Age Estimation by Radiographic Examination (Demirjian’s Method)  

PubMed Central

Introduction: Dental age estimation methods are of particular value because teeth are highly resistant to mechanical, chemical, or physical impacts and time. Teeth are the strongest parts in the human body and are therefore very resistant to external influences, such as extreme temperatures, explosions, and other extreme conditions, which make them available for extensive postmortem periods. Aim: To correlate chronological age with dental age using Demirijian’s method. Materials and Methods: The study was carried out on 100 digital orthopantamograms (OPG) of patients in the age group of 7 to 24 years. During the analysis, Magnify’ and Ruler’ tools were used. Mandibular right third molar was used for entire study. Data collected was analysed by using SPSS software. Results: Development of third molar in all stages was found slightly earlier in males than in females, when chronological age was compared with dental age using Demirjian method. 88% subject showed statistically significant linear correlation between chronological age and developmental age using Demirjian’s method. Conclusion: The linear correlation between chronological age and dental age using to Demirjian’s method was more in age group above 16 years and less in age group below 16 years. Demirijian’s method is a reliable guide for age estimation in age group of 7 to 24 years of age. PMID:24995239

Patil, Swapnil N; Kamble, Seema D; Mowade, Tushar; Motghare, Pavan

2014-01-01

212

Molecular dynamics simulation of the molar volumes and solubility parameters of straight alkanes  

NASA Astrophysics Data System (ADS)

The straight chain n-alkanes used as core materials to fabricate nanoencapsulated and microencapsulated phase change of materials (PCM) have received much attention in recent years. The dissipative particle dynamics (DPD) simulation method has been emerged to investigate the encapsulated PCM from the perspective of mesoscopic. To obtain the Flory-Huggins and repulsion parameters, which is essential for the DPD study, the molar volume and solubility parameter of straight alkanes are investigated by using molecular dynamics (MD) simulation. The results showed that a linear relationship of molar volume (V) with carbon atom number (n) and simulation temperature (T) can be obtained as: V = -31.73 + 0.26T + 14.82n. A nonlinear relationship of solubility parameter (?) with carbon atom number and simulation temperature can be described as: ? = 18.45-3.66 ×10-2n + 1.07T - 1.20 ×10-5n2 - 9.60 ×10-2T2 - 2.49 ×10-3nT. The equations can be used as a reference for the further DPD simulation in n-alkanes based PCM system.

Liu, Xinjian; Rao, Zhonghao; Huo, Yutao

2014-12-01

213

Identification of possible factors impacting dental students' ability to locate MB2 canals in maxillary molars.  

PubMed

This study examined the effect of the access size and straight-line path of access on third-year dental students' ability to locate a second mesiobuccal (MB2) canal in maxillary first and second molars. One hundred and six third-year dental students at one Faculty of Dentistry performed simulated root canal treatment with the aid of 2x magnification loupes on extracted teeth. A postgraduate endodontic student subsequently made a reasonable search for an untreated MB2 canal with the aid of a dental operating microscope. The mesiobuccal roots were then sectioned horizontally for determination of the canal configuration. The dental students were able to treat an MB2 canal in 15.8 percent of the teeth, but this was not associated with satisfactory access criteria. The postgraduate endodontic student identified an MB2 canal in 54.7 percent of the remaining tooth samples excluding those where the MB2 canal was found by the dental students; this represented 94.3 percent of those teeth confirmed by horizontal sectioning of the root to have an MB2 canal. The postgraduate student troughed, on average, 2.6 mm before negotiating the MB2 canal. As satisfactory access criteria and straight-line path of access did not correlate with the dental students' ability to find a second mesiobuccal canal, this result has important implications for educational goals with respect to endodontic treatment of maxillary molar teeth. PMID:24789839

Park, Ellen; Chehroudi, Babak; Coil, Jeffrey M

2014-05-01

214

Treatment effects of intraoral appliances with conventional anchorage designs for non-compliance maxillary molar distalization: a literature review.  

PubMed

Since the end of the 1970s, various appliances with intramaxillary anchorage for distalization of the upper molars have been described as an alternative to headgear. The major advantages of these innovative appliances are that they act permanently and are independent of patient compliance. The purpose of this study was to compare the efficiency, both quantitatively and qualitatively, of various appliance types with intramaxillary anchorage for non-compliance molar distalization. Eighty-five papers were reviewed, and 22 were identified as being suitable for inclusion. The selection was based on compliance with the following criteria: treatment group with at least 10 non-syndromal patients, conventional intraoral anchorage design using a palatal button and anchorage teeth, consistent cephalometric measurements in clinical-epidemiological studies, exact data on the course of treatment, and statistical presentation of the measured outcomes and their standard deviations. The results show that non-compliance molar distalization is possible with numerous different appliances. While molar distalization with standard pendulum appliances exhibited the largest values for dental-linear distalization, it also resulted in concurrent, substantial therapeutically undesirable distal tipping. However, specific modifications to the pendulum appliance allow achievement of almost bodily molar distalization. Different outcomes are quoted in the studies for the efficiency of loaded spring systems for distal molar movement, but it seems that the first class appliance and the palatal distal jet are more efficient than the vestibular Jones Jig. The studies identify anchorage loss as being found in the area of the incisors rather than the area of the first premolars. There was a trend for more substantial reciprocal side-effects to occur when only two teeth were included in the anchorage unit. Vertical components acting on the molars, premolars, and incisors, such as intrusion and extrusion, tended to be of secondary importance and, therefore, may be disregarded. PMID:18820306

Kinzinger, Gero S M; Eren, Mert; Diedrich, Peter R

2008-12-01

215

The Component Slope Linear Model for Calculating Intensive Partial Molar Properties: Application to Waste Glasses and Aluminate Solutions - 13099  

SciTech Connect

Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOHNaAl(OH){sub 4}-H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results determined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components. (authors)

Reynolds, Jacob G. [Washington River Protection Solutions, LLC, P.O. Box 850, Richland, WA 99352 (United States)] [Washington River Protection Solutions, LLC, P.O. Box 850, Richland, WA 99352 (United States)

2013-07-01

216

The component slope linear model for calculating intensive partial molar properties /application to waste glasses and aluminate solutions  

SciTech Connect

Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOH-NaAl(OH){sub 4}-H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results determined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components.

Reynolds, Jacob G. [Washington River Protection Solutions, LLC, Richland, WA (United States)

2013-01-11

217

Accuracy of identifying juvenile/adult status from third molar development using prediction probabilities derived from logistic regression analysis.  

PubMed

The use of third molars in predicting juvenile/adult status (molar development was assessed using Köhler's grading on 268 orthopantomograms of Indian subjects. Logistic regression analysis was applied to determine allocation accuracy of juvenile/adult status and the level of probability that is "reliable" in predicting juvenile/adult status. Allocation accuracies ranged between 75.8% and 78.2% for the sexes combined, with minimal male-female differences. Adults were categorized more accurately than juveniles, suggesting that Köhler's grading puts Indian juveniles at greater risk of unwarranted punishment. In both sexes, juvenile/adult status was "reliably" predicted when the probability was >80% using individual third molars (excepting the lower right third molar in males); combining upper and lower third molars on the left/right sides, "reliable" predictions were possible when the probability was >80% and >90% for females and males, respectively. Overall, "reliable" juvenile/adult status prediction was achieved in c. 36% of subjects. PMID:24313875

Acharya, Ashith B; Bhowmik, Biyas; Naikmasur, Venkatesh G

2014-05-01

218

Differences in molar relationships and occlusal contact areas evaluated from the buccal and lingual aspects using 3-dimensional digital models  

PubMed Central

Objective The aims of this study were to use a 3-dimensional (3D) system to compare molar relationship assessments performed from the buccal and lingual aspects, and to measure differences in occlusal contact areas between Class II and Class I molar relationships. Methods Study casts (232 pairs from 232 subjects, yielding a total of 380 sides) were evaluated from both the buccal and lingual aspects, so that molar relationships could be classified according to the scheme devised by Liu and Melsen. Occlusal contact areas were quantified using 3D digital models, which were generated through surface scanning of the study casts. Results A cusp-to-central fossa relationship was observed from the lingual aspect in the majority of cases classified from the buccal aspect as Class I (89.6%) or mild Class II (86.7%). However, severe Class II cases had lingual cusp-to-mesial triangular fossa or marginal ridge relationships. Mean occlusal contact areas were similar in the Class I and mild Class II groups, while the severe Class II group had significantly lower values than either of the other 2 groups (p < 0.05). Conclusions Buccal and lingual assessments of molar relationships were not always consistent. Occlusal contact areas were lowest for the Class II-severe group, which seems to have the worst molar relationships - especially as seen from the lingual aspect. PMID:23112949

Jang, Sook-Yoon; Kim, Minji

2012-01-01

219

Economic modeling of sealing primary molars using a "value of information" approach.  

PubMed

The objective was to evaluate 2 primary molar sealant strategies for publicly insured children using an "expected value of perfect information" (EVPI) approach. We converted a 10,000-observation tooth-level cost-effectiveness simulation model comparing 2 primary molar sealant strategies - always seal (AS) and standard care (SC) - with a 1,250-observation child-level model. Costs per child per restoration or extraction averted were estimated. Opportunity losses under the AS strategy were determined for children for whom SC was the optimal choice. We determined the EVPI by multiplying mean opportunity losses by the projected incident population of publicly insured 3-year-olds in the US over 10 years with costs discounted at 2%. All analyses were conducted under assumptions of high and low intrachild correlations between at-risk teeth. The AS strategy cost $43.68 over SC (95% CI: -$5.50, $92.86) per child per restoration or extraction averted under the high intrachild correlation assumption and $15.54 (95% CI $7.86, $23.20) under the low intrachild correlation. Under high intrachild correlation, mean opportunity losses were $80.28 (95% CI: $76.39, $84.17) per child, and AS was the optimal strategy in 31% of children. Under low correlation, mean opportunity losses were $14.61 (95% CI: $12.20, $17.68) and AS was the optimal strategy in 87% of children. The EVPI was calculated at $530,813,740 and $96,578,389 (for high and low intrachild correlation, respectively), for a projected total incident population of 8,059,712 children. On average, always sealing primary molars is more effective than standard care, but widespread implementation of this preventive approach among publicly insured children would result in large opportunity losses. Additional research is needed to identify the subgroups of publicly insured children who would benefit the most from this effective and potentially cost-saving public health intervention. PMID:25056993

Ney, J P; van der Goes, D N; Chi, D L

2014-09-01

220

Excess molar volumes and excess molar enthalpies of binary and ternary mixtures of 1-butanol, a tertiary amine (tri- n-butylamine or tri- n-octylamine) and n-hexane: Experimental results and ERAS-model calculations  

Microsoft Academic Search

Experimental data at T=298.15K and ambient pressure of excess molar volumes VmE and excess molar enthalpies HmE are reported for two ternary and the corresponding binary mixtures of {1-butanol, tri-n-butylamine (TBA), or tri-n-octylamine (TOA), and n-hexane}. A vibrating-tube densitometer was used to determine VmE. HmE was measured using a quasi-isothermal flow calorimeter. The experimental results are used to test the

Matthias Kwaterski; Elena N. Rezanova; Rüdiger N. Lichtenthaler

2006-01-01

221

Treatment of infra-occluded primary molars in patients with dental ageneses.  

PubMed

When dental agenesis is encountered, several treatment solutions can be considered: extraction of the primary tooth and closure of the space or, alternatively, conservation of the space with the primary tooth still on the arch until a prosthesis can be placed. In the presence of premolar agenesis, the corresponding primary molar may be infra-occluded relative to the occlusal plane. This situation complicates the treatment plan. Depending on the clinical setting, it can be useful to restore occlusal contacts using composite overlays. We will demonstrate this treatment option via two clinical cases. Tooth conservation helps maintain the bone volume that will later facilitate placement of an implant and limit extrusion of the antagonists as well as tipping of the neighboring teeth. PMID:25092254

Medio, Marie; de la Dure Molla, Muriel

2014-09-01

222

Solution properties of high-molar-mass hyaluronans: the biopolymer degradation by ascorbate.  

PubMed

An accurate molecular characterization, molar mass and size distributions, of 10 hyaluronan (HA) samples was performed by using a multi-angle light scattering detector connected on-line to a size exclusion chromatographic system. The dynamic viscosity eta of the HA solutions was investigated using a rotational viscometer. On monitoring the sample dynamic viscosity for up to 5h, a small however constant increase of the eta value was observed, indicating rheopectic behavior of all 10 HA solutions. Addition of ascorbic acid to the HA solutions caused significant changes in the rheological properties of the samples investigated. The change of eta values in the course of time was explained by the redox reactions (caused by the added ascorbate) that occur during the dynamic viscosity monitoring. PMID:17362893

Soltés, Ladislav; Valachová, Katarína; Mendichi, Raniero; Kogan, Grigorij; Arnhold, Juergen; Gemeiner, Peter

2007-06-11

223

Stepwise excavation in a permanent molar: 17-year follow-up.  

PubMed

The current study presents a 17-year clinical report of stepwise excavation and indirect pulp capping in a lower right first molar, with great dentin destruction and a lack of dentin support of the cusps. At the first appointment, indirect pulp capping with calcium hydroxide and a temporary filling with zinc oxide cement were performed to minimize the risk of pulp exposure during excavation. After 45 days, the remaining carious tissue was removed and a restoration with glass-ionomer lining (Vitrebond) and resin composite (P-50) was performed. Satisfactory morphology and function of the restoration and pulp vitality were preserved for 17 years, thus indicating that stepwise excavation can be a good treatment alternative in selected cases. PMID:20672734

Lima, Fernanda Ferruzzi; Pascotto, Renata Corrêa; Benetti, Ana Raquel

2010-01-01

224

Coumarin-bearing triarylamine sensitizers with high molar extinction coefficient for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Coumarin unit is introduced into triarylamine and three organic sensitizers are designed and synthesized with triarylamine bearing coumarin moiety as the electron donor, conjugated system containing thiophene unit as the ?-bridge, and cyanoacetic acid moiety as the electron acceptor. The light-harvesting capabilities and photovoltaic performance of these dyes are investigated systematically with the comparison of different ?-bridges. High molar extinction coefficients are observed in these triarylamine dyes and the photocurrent and photovoltage are increased with the introduction of another thiophene or benzene. Optimal photovoltaic performance (? = 6.24%, Voc = 690 mV, Jsc = 14.33 mA cm-2, and ff = 0.63) is observed in the DSSC based on dye with thiophene-phenyl unit as the ?-conjugated bridge under 100 mW cm-2 simulated AM 1.5 G solar irradiation.

Zhong, Changjian; Gao, Jianrong; Cui, Yanhong; Li, Ting; Han, Liang

2015-01-01

225

Multiple Dens Evaginatus of Premolars and Molars in Chinese Dentition: A Case Report and Literature Review  

PubMed Central

Dens evaginatus (DE) is a dental anomaly that occurs as an accessory tubercle on the occlusal or lingual surface of a tooth. The authors provide a literature review and report a rare case in which DE occurs on multiple mandibular premolars and maxillary molars. The patient is a 26-year-old Chinese woman, with a chief complaint of gingival bleeding. DE affecting teeth 17, 27, 35, and 45 was found during clinical examination. For treatment of the patient, we reduced the opposing occluding teeth, while undertaking progressive grinding of the tubercles for six months. We followed-up for a year. This suggests the importance of examining for multiple DE during clinical practice. PMID:21125795

Rao, Yan-gang; Guo, Li-yang; Hu, Tao

2010-01-01

226

Molar microwear of subfossil lemurs: improving the resolution of dietary inferences.  

PubMed

In this study we use molar microwear analyses to examine the trophic distinctions among various taxa of Malagasy subfossil lemurs. High resolution casts of the teeth of Megaladapis, Archaeolemur, Palaeopropithecus, Babakotia, and Hadropithecus were examined under a scanning electron microscope. Megaladapis was undoubtedly a browsing folivore, but there are significant differences between species of this genus. However, dietary specialists appear to be the exception; for example, Palaeopropithecus and Babakotia probably supplemented their leaf-eating with substantial amounts of seed-predation, much like modern indrids. Hadropithecus was decidedly not like the modern gelada baboon, but probably did feed on hard objects. Evidence from microwear and coprolites suggests that Archaeolemur probably had an eclectic diet that differed regionally and perhaps seasonally. Substantial trophic diversity within Madgascar's primate community was diminished by the late Quaternary extinctions of the large-bodied species (>9 kg). PMID:12457853

Rafferty, K L; Teaford, M F; Jungers, W L

2002-11-01

227

A comparison of the effects of methylprednisolone and tenoxicam on pain, edema, and trismus after impacted lower third molar extraction  

PubMed Central

Background The aim of the present study was to compare the effects of preemptive intravenous tenoxicam and methylprednisolone administrations on extraction of impacted third molars. Material/Methods This was a placebo-controlled, randomized, double-blind, clinical trial. A total of 60 adult patients ages 18–40 years with the complaints of impacted third molar teeth were included in the study. Results The postoperative swelling ratios (p<0.05) and pain scores (p<0.05) were significantly better in both study groups than in the control group and there was no statistically significant difference between methylprednisolone and tenoxicam groups with regards to the edema and pain relief. Conclusions Preoperative administration of 80 mg methylprednisolone achieves better control of trismus than tenoxicam without any significant differences in edema and pain control in impacted third molar teeth extraction. PMID:24473372

Ilhan, Ozgur; Agacayak, Kamil Serkan; Gulsun, Belgin; Koparal, Mahmut; Gunes, Nedim

2014-01-01

228

Molar-mass measurement of a 28Si-enriched silicon crystal for determination of the Avogadro constant  

NASA Astrophysics Data System (ADS)

The molar mass of a 28Si-enriched crystal was measured at the National Metrology Institute of Japan to determine the Avogadro constant by the x-ray crystal density method as part of the International Avogadro Coordination project. The molar mass was determined by isotope ratio measurements using a multicollector inductively coupled plasma mass spectrometer combined with an isotope dilution technique. The 28Si-enriched crystal was dissolved in tetramethylammonium hydroxide and three different blended solutions were used to correct for mass bias in the measurement. The molar mass of the 28Si-enriched crystal was determined to be 27.976?970 09 g mol-1 with a standard uncertainty of 0.000?000 14 g mol-1. This corresponds to a relative standard uncertainty of 5.2 × 10-9. This result is consistent with measurements reported by the Physikalisch-Technische Bundesanstalt, Germany.

Narukawa, Tomohiro; Hioki, Akiharu; Kuramoto, Naoki; Fujii, Kenichi

2014-06-01

229

Reliability of CBCT as an assessment tool for mandibular molars furcation defects  

NASA Astrophysics Data System (ADS)

Introduction. In numerous clinical situations it is not possible to have an exact clinical evaluation of the furcation defects. Recently the use of CBCT in periodontology has led to an increased precision in diagnostic. Aim. To determine the accuracy of CBCT as diagnostic tool of the furcation defects. Material and method. 19 patients with generalised advanced chronic periodontitis were included in this study, presenting a total of 25 lower molars with different degrees of furcation defects. Clinical and digital measurements (in mm) were performed on all the molars involved. The data obtained has been compared and statistically analysed. Results. The analysis of primary data has demonstrated that all the furcation grade II and III defects were revealed using the CBCT technique. Regarding the incipient defects (grade I Hamp < 3mm), the dimensions measured on CBCT images were slightly bigger. The results have shown that 84% of the defects detected by CBCT have been confirmed by clinical measurements. These data are similar to those revealed by other studies1. Conclusions. The use of CBCT technique in evaluation and diagnosis of human mandibular furcation defects can provide many important information regarding the size and aspect of the interradicular defect, efficiently and noninvasively. CBCT technique is used more effectively in detection of advanced furcation degree compared to incipient ones. However, the CBCT examination cannot replace, at least in this stage of development, the clinical measurements, especially the intraoperative ones, which are considered to represent the „golden standard" in this domain.

Marinescu, Adrian George; Boariu, Marius; Rusu, Darian; Stratul, Stefan-Ioan; Ogodescu, Alexandru

2014-01-01

230

Temperature dependent near UV molar absorptivities of several small aldehydes in aqueous solution  

NASA Astrophysics Data System (ADS)

Temperature-dependent molar absorptivities are reported for benzaldehyde, acrolein, isobutyraldehyde, pentanal, and hexanal in aqueous solution. With the exception of acrolein, molar absorptivities are given at eight temperatures in the range 6.5-69.5°C for wavelengths greater than 200 nm, a spectral resolution of 2.0 nm, and a spacing of 2.5 nm. For acrolein, data are given over a more limited range of temperatures and wavelengths. For benzaldehyde and acrolein, no hydration occurs, as expected, and only small changes in the shape and intensity of the spectrum with temperature are observed. For the other three aldehydes, the hydration reaction RCHO+ H2O? RCH(OH)2; K hyd=[ RCH(OH)2]/[ RCHO] is the major source for the observed change in intensity with temperature. Based on these changes, the following thermodynamic parameters are obtained for the hydration reaction at T = 25° C: isobutyraldehyde, Khyd = 0.51 ± 0.06, ?H = - 26.8 ± 1.9 kJ mol -1, ?S = - 95 ± 7 J mol -1 K -1; pentanal, Khyd = 0.55 ± 0.05, ?H = - 24.6 ± 1.6 kJ mol -1, ?S = - 87 ± 8 J mol -1 K -1; hexanal, Khyd = 0.49 ± 0.05, ?H = - 25.3 ± 2.2 kJ mol -1, ?S = - 91 ± 8 J mol -1 K -1. The present results are compared to data obtained previously for smaller aliphatic aldehydes, and the implications of the results for aqueous phase atmospheric chemistry are discussed.

Sham, Yuk Y.; Joens, Jeffrey A.

1995-02-01

231

Dental pulp of the third molar: a new source of pluripotent-like stem cells.  

PubMed

Dental pulp is particularly interesting in regenerative medicine because of the accessibility and differentiation potential of the tissue. Dental pulp has an early developmental origin with multi-lineage differentiation potential as a result of its development during childhood and adolescence. However, no study has previously identified the presence of stem cell populations with embryonic-like phenotypes in human dental pulp from the third molar. In the present work, we describe a new population of dental pulp pluripotent-like stem cells (DPPSCs) that were isolated by culture in medium containing LIF, EGF and PDGF. These cells are SSEA4(+), OCT3/4(+), NANOG(+), SOX2(+), LIN28(+), CD13(+), CD105(+), CD34(-), CD45(-), CD90(+), CD29(+), CD73(+), STRO1(+) and CD146(-), and they show genetic stability in vitro based on genomic analysis with a newly described CGH technique. Interestingly, DPPSCs were able to form both embryoid-body-like structures (EBs) in vitro and teratoma-like structures that contained tissues derived from all three embryonic germ layers when injected in nude mice. We examined the capacity of DPPSCs to differentiate in vitro into tissues that have similar characteristics to mesoderm, endoderm and ectoderm layers in both 2D and 3D cultures. We performed a comparative RT-PCR analysis of GATA4, GATA6, MIXL1, NANOG, OCT3/4, SOX1 and SOX2 to determine the degree of similarity between DPPSCs, EBs and human induced pluripotent stem cells (hIPSCs). Our analysis revealed that DPPSCs, hIPSC and EBs have the same gene expression profile. Because DPPSCs can be derived from healthy human molars from patients of different sexes and ages, they represent an easily accessible source of stem cells, which opens a range of new possibilities for regenerative medicine. PMID:22467856

Atari, Maher; Gil-Recio, Carlos; Fabregat, Marc; García-Fernández, Dani; Barajas, Miguel; Carrasco, Miguel A; Jung, Han-Sung; Alfaro, F Hernández; Casals, Nuria; Prosper, Felipe; Ferrés-Padró, Eduard; Giner, Luis

2012-07-15

232

Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures.  

PubMed

The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol VE as a function of ethanol mole fraction XE is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has "brittle" hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water. PMID:25681917

Tan, Ming-Liang; Miller, Benjamin T; Te, Jerez; Cendagorta, Joseph R; Brooks, Bernard R; Ichiye, Toshiko

2015-02-14

233

Volume analysis of heat-induced cracks in human molars: A preliminary study  

PubMed Central

Context: Only a few methods have been published dealing with the visualization of heat-induced cracks inside bones and teeth. Aims: As a novel approach this study used nondestructive X-ray microtomography (micro-CT) for volume analysis of heat-induced cracks to observe the reaction of human molars to various levels of thermal stress. Materials and Methods: Eighteen clinically extracted third molars were rehydrated and burned under controlled temperatures (400, 650, and 800°C) using an electric furnace adjusted with a 25°C increase/min. The subsequent high-resolution scans (voxel-size 17.7 ?m) were made with a compact micro-CT scanner (SkyScan 1174). In total, 14 scans were automatically segmented with Definiens XD Developer 1.2 and three-dimensional (3D) models were computed with Visage Imaging Amira 5.2.2. The results of the automated segmentation were analyzed with an analysis of variance (ANOVA) and uncorrected post hoc least significant difference (LSD) tests using Statistical Package for Social Sciences (SPSS) 17. A probability level of P < 0.05 was used as an index of statistical significance. Results: A temperature-dependent increase of heat-induced cracks was observed between the three temperature groups (P < 0.05, ANOVA post hoc LSD). In addition, the distributions and shape of the heat-induced changes could be classified using the computed 3D models. Conclusion: The macroscopic heat-induced changes observed in this preliminary study correspond with previous observations of unrestored human teeth, yet the current observations also take into account the entire microscopic 3D expansions of heat-induced cracks within the dental hard tissues. Using the same experimental conditions proposed in the literature, this study confirms previous results, adds new observations, and offers new perspectives in the investigation of forensic evidence. PMID:25125923

Sandholzer, Michael A.; Baron, Katharina; Heimel, Patrick; Metscher, Brian D.

2014-01-01

234

Strongly Composition-Dependent Partial Molar Compressibility of Water in Silicate Glasses  

NASA Astrophysics Data System (ADS)

Water and other volatiles have long been known to play a fundamental role in igneous processes, yet their influence on the physical properties of melts are still not well enough understood. Of particular interest is the density contrast between liquid and solid phases, which facilitates melt extraction and migration. Owing to its low molecular weight, dissolved water must decrease magma density, but the way it does so as a function of pressure remains largely to be determined. Studies on quenched melts (glasses) provide useful information because the glass has the same structure as the melt. We measured compressional and shear wave velocities of seven series of hydrous aluminosilicate glasses by Brillouin scattering at room temperature and pressure. The glasses were quenched from high temperature and 2 or 3 kbar pressure. The dry end-members range from highly polymerized albitic and granitic compositions, to depolymerized synthetic analogues of mantle-derived melts. For each set of glasses, the adiabatic shear and bulk moduli have been calculated from the measured sound velocities and densities. These moduli are linear functions of water content up to 5 wt % H2O, the highest concentration investigated, indicating that both are independent of water speciation in all series. For water-free glasses, the bulk modulus decreases from about 65 to 35 GPa with increasing degree of polymerization. Sympathetically, the partial molar bulk modulus of the water component decreases from 114 to 8 GPa, such that dissolved water amplifies the differences in rigidity between the anhydrous glasses. This strong variation indicates that the solubility mechanisms of water depend strongly on silicate composition. Depolymerized liquids are also much less compressible than their polymerized counterparts, suggesting that the partial molar compressibility of dissolved water approaches zero in depolymerized liquids. If this is correct, hydrous mantle melts formed beneath volcanic arcs would be more buoyant at depth than previously thought, facilitating their extraction and rapid ascent.

Whittington, A. G.; Richet, P.; Polian, A.

2010-12-01

235

Lipid Concentration and Molar Ratio Boundaries for the Use of Isotropic Bicelles  

PubMed Central

Bicelles are model membranes generally made of long-chain dimyristoylphosphatidylcholine (DMPC) and short-chain dihexanoyl-PC (DHPC). They are extensively used in the study of membrane interactions and structure determination of membrane-associated peptides, since their composition and morphology mimic the widespread PC-rich natural eukaryotic membranes. At low DMPC/DHPC (q) molar ratios, fast-tumbling bicelles are formed in which the DMPC bilayer is stabilized by DHPC molecules in the high-curvature rim region. Experimental constraints imposed by techniques such as circular dichroism, dynamic light scattering, or microscopy may require the use of bicelles at high dilutions. Studies have shown that such conditions induce the formation of small aggregates and alter the lipid-to-detergent ratio of the bicelle assemblies. The objectives of this work were to determine the exact composition of those DMPC/DHPC isotropic bicelles and study the lipid miscibility. This was done using 31P nuclear magnetic resonance (NMR) and exploring a wide range of lipid concentrations (2–400 mM) and q ratios (0.15–2). Our data demonstrate how dilution modifies the actual DMPC/DHPC molar ratio in the bicelles. Care must be taken for samples with a total lipid concentration ?250 mM and especially at q ? 1.5–2, since moderate dilutions could lead to the formation of large and slow-tumbling lipid structures that could hinder the use of solution NMR methods, circular dichroism or dynamic light scattering studies. Our results, supported by infrared spectroscopy and molecular dynamics simulations, also show that phospholipids in bicelles are largely segregated only when q > 1. Boundaries are presented within which control of the bicelles’ q ratio is possible. This work, thus, intends to guide the choice of q ratio and total phospholipid concentration when using isotropic bicelles. PMID:24797658

2014-01-01

236

Distribution of BMP6 in the alveolar bone during mouse mandibular molar eruption.  

PubMed

Eruption requires synchrony of the tooth with the surrounding tissues, particularly the bone. One important step during eruption is remodelling of the alveolar bone at the base of the tooth and along the roots. Expression of BMP6 was reported to be increased in the basal half of the dental follicle prior to eruption and inhibition of BMP6 affected bone formation at the base of the alveolar crypt. The aim of this study was to further investigate BMP6 protein in relation to tooth eruption and the corresponding bone remodelling using temporospatial correlations of BMP6 localization with morphogenetic events (proliferation, differentiation, apoptosis and bone apposition/resorption), other BMPs (BMP2 and BMP7) and three-dimensional images of tooth-bone development. BMP6 expression pattern was mapped in the mandibular molar teeth and related structures around eruption. Localization of BMP6 dominated in osteoblasts, in regions of bone formation within the alveolar crypt. These findings positively correlated with proliferation at the tooth base region, osteocalcin expression in the osteoblasts/osteocytes and BMP2 and BMP7 presence in the alveolar bone surrounding the tooth. Osteoclast activity and apoptotic elimination in the root region gradually decreased before eruption and totally ceased at eruption stages. Generally, BMP6 positively correlated with BMP2, BMP7 and osteocalcin-positive osteoblasts, and areas of bone remodelling. Moreover, BMP6 was found in the periodontium and cementoblasts. BMP6 expression in the alveolar bone accompanied tooth eruption. Notably, the expression pattern of BMP6 in the bone did not differ around individual molar teeth at the same stage of development. The expression of BMP6 in periodontal ligaments may contribute to interaction between the tooth and bone during the eruption and anchoring process. PMID:25084210

Oralová, Veronika; Chlastáková, Ivana; Radlanski, Ralf Johannes; Matalová, Eva

2014-01-01

237

Manual and Rotary Instrumentation Ability to Reduce Enterococcus faecalis Associated with Photodynamic Therapy in Deciduous Molars.  

PubMed

This aim of this study was to assess the ability of manual or rotary instrumentation associated with photodynamic therapy (PDT) to reduce Enterococcus faecalis using three combinations of light/photosensitizers: toluidine blue O/laser, fuchsin/halogen light and fuchsin/LED. Twenty deciduous molars were selected and contaminated with Enterococcus faecalis (McFarland 0.5 scale). Working length determination was performed by visual method. The teeth were randomly divided into two groups: G1 (n=10): manual instrumentation (Kerr-type files) and G2 (n=10): rotary instrumentation (ProTaper system). The bacteria were collected three times using sterile paper cones compatible with the anatomic diameter of the root canal for 30 s before and after instrumentation and after PDT. The samples were diluted in peptone water, seeded on blood agar plates and incubated in an oven at 37 °C for colony-forming units counting. The decrease of E. faecalis counts after instrumentation and after PDT was compared using the Wilcoxon test, t-test and Kruskal Wallis test. A significant reduction of E. faecalis occurred after manual and rotary instrumentation and after PDT using the three combinations of light/photosensitizer (p<0.05). It may be concluded that both rotary and manual instrumentation reduced E. faecalis. Fuchsin with halogen light or LED irradiation and toluidine blue O with laser irradiation can be used to reduce E. faecalis in root canals of primary molars. PDT can be used as an adjuvant to conventional endodontic treatment. PMID:25590196

Pinheiro, Sérgio Luiz; Silva, Josianne Neres da; Gonçalves, Rafael Orro; Villalpando, Karina Teixeira

2014-12-01

238

Treatment Outcomes of Primary Molars Direct Pulp Capping after 20 Months: A Randomized Controlled Trial  

PubMed Central

Introduction The aim of this randomized controlled trial was to compare the radiographic and clinical success rates of direct pulp capping (DPC) using ProRoot mineral trioxide aggregate (MTA) or calcium enriched mixture (CEM). Methods and Materials A total of 42 symptom-free carious vital primary molars (21 pairs) were selected in this split mouth trial and randomly pulpotomized in two experimental groups. Pinpoint pulp exposures were covered by the same blinded operator with MTA or CEM, and then restored by amalgam. Radiographic and clinical successes were evaluated at 20 month follow-up. Data were statistically analyzed using McNemar test. Results Nineteen patients were available for 20-month follow-up; only one failed tooth was extracted in the CEM group. All available teeth were symptom-free, however, the final evaluated success rate was 89% in CEM (CI 95%: 0.82-0.96) and 95% in MTA (CI 95%: 0.85-1) groups without statistical difference (P=0.360). Worst case scenario was applied for missing value analysis; assuming that the 2 lost cases in CEM group had failed and the only lost case in MTA group was due to treatment success, as a result the success of CEM and MTA were 81% (CI 95%: 0.72-0.90) and 95% (CI 95%:0.85-1), respectively, with no statistical difference (P=0.078). In the reverse scenario, the success of MTA and CEM were 86% (CI 95%: 0.78-0.94) and 90% (CI 95%: 0.82-0.98), respectively; again with no statistical difference (P=0.479). Conclusion Effectiveness of MTA and CEM biomaterials for primary molars’ DPC was similar; CEM can be a suitable alternative for MTA. PMID:24171019

Fallahinejad Ghajari, Masoud; Asgharian Jeddi, Tahereh; Iri, Sonay; Asgary, Saeed

2013-01-01

239

Three Independent Mesial Canals in a Mandibular Molar: Four-Year Followup of a Case Using Cone Beam Computed Tomography  

PubMed Central

Endodontic treatment of mandibular molars is challenging because of variable root canal morphology. The nonsurgical endodontic management of a mandibular first molar presenting an independent middle mesial canal is reported. After coronal access, additional clinical inspection of the mesial canals' orifices and their interconnecting groove using an endodontic explorer and 4.5× loupes enabled the identification of the middle mesial canal orifice. All root canals were chemomechanically prepared and filled. The tooth was asymptomatic and functional after 4?years of followup. Cone beam computed tomography (CBCT) images revealed normal periapical status and three-dimensional (3D) anatomical aspects of the root canal system. PMID:23662215

de Paula, Adrianne Freire; Brito-Júnior, Manoel; Quintino, Alex Carvalho; Camilo, Carla Cristina; Cruz-Filho, Antônio Miranda; Sousa-Neto, Manoel Damião

2013-01-01

240

Penetration of experimental infiltrants with different penetration coefficients and ethanol addition into natural caries lesions in primary molars.  

PubMed

This study evaluated the influence of the penetration coefficient (PC) and ethanol addition on the penetration depth (PD) of experimental infiltrants into proximal caries lesions in primary molars. Caries lesions (n = 45) were randomly treated with 1 of 4 experimental infiltrants (PC63; PC185; PC204; PC391) for 5 min. Lesion depths and PDs were analysed using dual fluorescence confocal microscopy. Lesions were almost completely infiltrated in all groups. Median PDs and percentage penetrations were not significantly different between groups (p > 0.05). When applied for 5 min, all tested infiltrants were able to infiltrate proximal caries in primary molars nearly completely. PMID:22472477

Paris, S; Soviero, V M; Chatzidakis, A J; Meyer-Lueckel, H

2012-01-01

241

The Partial Molar Volume and Heat Capacity of the Glycyl Group in Aqueous Solution at 25^C  

Microsoft Academic Search

The partial molar volumes, V2\\u000a ^, and the partial molar heat capacities, Cp,2\\u000a ^, at infinite dilution have been determined for three new peptides of sequence seryl(glycyl)xglycine, where x=0 to 2, in aqueous solution at 25^C. Values for V2\\u000a ^ at 25°C have also been determined for two neutral peptide derivatives N-acetylglycylglycinamide and N-acetylglycylglycylglycinamide. These V2\\u000a °; and Cp,2\\u000a °;

Nessha M. Wise; Gavin R. Hedwig

2006-01-01

242

A comparitive study of diclofenac transdermal patch against oral diclofenac for pain control following removal of mandibular impacted third molars  

Microsoft Academic Search

Objective  The objectives of this study was to evaluate subjectively the analgesic efficacy of Oral Diclofenac Sodium against Diclofenac\\u000a Sodium Transdermal patch in the management of postoperative pain following surgical removal of impacted mandibular third molars.\\u000a \\u000a \\u000a \\u000a Materials and methods  Twenty healthy subjects belonging to both the sexes in the age group of 18–40 years with bilateral mesioangular impactions\\u000a of mandibular third molar

Prithvi S. Bachalli; H. Nandakumar; N. Srinath

2009-01-01

243

CBCT diagnosis and endodontic management of a maxillary first molar with unusual anatomy of two palatal canals: A case report  

PubMed Central

It is crucial for any clinician to have a thorough knowledge about the normal anatomy of tooth and always be vigilant for any variations to ensure endodontic success. An anatomic variant like additional canals in the palatal root of maxillary molar is not commonly reported. This clinical case report presents the application of cone beam computed tomography as a useful imaging technique in endodontics for the management of teeth with aberrant anatomy. Here, maxillary first molar having two canals in the palatal root, two canals in mesiobuccal root and one canal in distobuccal root was managed successfully using cone beam computed tomography scan as a diagnostic aid. PMID:25125860

Sharma, Sarang; Sharma, Vivek; Grover, Shibani; Mittal, Meenu

2014-01-01

244

Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide.  

PubMed

The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide. PMID:25169720

Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng

2014-10-01

245

Análise comparativa entre os anestésicos locais Articaína 4% e Prilocaína 3% na extração de terceiros molares retidos em humanos  

Microsoft Academic Search

Comparative analysis between the local anesthesics Articaine 4% and Prilocaine 3% on human third molar removals. The local anesthesics are the most used drugs in Dentistry. They are frequently used in surgery, because pain has been described as an unpleasant experience, both on sensorial and psychological levels. The aim of this study was to obtain further knowledge about articaine 4%

Fausto Rodrigo Victorino; Aparecido Neri Daniel; Liogi Iwaki Filho; Edevaldo Tadeu Camarini; Josmar Mazucheli; Ângelo José Pavan

2004-01-01

246

on the basis of regressions of molar area versus body mass in living primates29 . The smaller  

E-print Network

on the basis of regressions of molar area versus body mass in living primates29 . The smaller primate from this locality is Eosimias centennicus, a basal anthropoid that weighed 90­ 180 g on the basis derived from multiple regressions). Regressions of talar dimensions versus body mass in living primates30

Packer, Alissa A.

247

Use of palatal miniscrew anchorage and lingual multi-bracket appliances to enhance efficiency of molar scissors-bite correction.  

PubMed

This article reports the successful treatment method of scissors-bite correction using miniscrew anchorage and a lingual multi-bracket appliance. A female patient, 17 years and 4 months old, had a chief complaint of crowding of anterior teeth. The patient was given the diagnosis of Angle Class I malocclusion with bimaxillary protrusion and incisor crowding. She also showed a scissors-bite of the second molar on the right side. Miniscrews were inserted into the palatal region of the upper second molar to reinforce the anchorage, and a lingual multi-bracket appliance was placed into the maxilla. Miniscrews inserted palatally were used to correct the scissors-bite in the first 3 months; afterward, they were used to retract the six anterior teeth. The total active treatment period was 26 months. Because of the bite-plane effect, the upper and lower molars were separated in occlusion, and the scissors-bite was corrected effectively within a short time. The combined use of palatal miniscrew anchorage and lingual multi-bracket appliances enhances efficiency of molar scissors-bite correction. PMID:19413381

Tamamura, Nagato; Kuroda, Shingo; Sugawara, Yasuyo; Takano-Yamamoto, Teruko; Yamashiro, Takashi

2009-05-01

248

Partial molar adiabatic compressibilities and viscosities of some amino acids in aqueous glycerol solutions at 298.15 K  

Microsoft Academic Search

, ? and viscosity B-coefficients, and their corresponding transfer functions. The positive partial molar adiabatic compressibilities of transfer at infinite dilution, ?tr o s 2 , ? , have been observed for the studied amino acids (except at lower concentration up to ? 0.6 mB in some cases), and their magnitude increases with increase in concentration of glycerol. B-coefficient of

Gagandeep Singh; T S Banipal

249

The Role of Mandibular Third Molars on Lower Anterior Teeth Crowding and Relapse after Orthodontic Treatment: A Systematic Review  

PubMed Central

Aims. To evaluate the role of third molars in the development of crowding or relapse after orthodontic treatment in the anterior segment of the dental arch. Methods. PubMed search of the literature was performed selecting all the articles relevant to the topic and limiting the studies to controlled trials on humans and written in English language. Systematic review was conducted according to the PRISMA (preferred reporting items for systematic reviews and meta-analyses) statement. Results. A total of 12 clinical studies were included in the review. A high risk of bias was found in most of the articles, either because the relative items assessed were inadequate or because they were unclearly described. The third molars were not correlated with more severe anterior tooth crowding in most of the studies. However, four of them described a different outcome. Conclusion. Definitive conclusions on the role of the third molars in the development of anterior tooth crowding cannot be drawn. A high risk of bias was found in most of the trials, and the outcomes were not consistent. However, most of the studies do not support a cause-and-effect relationship; therefore, third molar extraction to prevent anterior tooth crowding or postorthodontic relapse is not justified. PMID:24883415

Zawawi, Khalid H.

2014-01-01

250

Characterization of the molar masses of hemicelluloses from wood and pulps employing size exclusion chromatography and matrix-assisted laser desorption ionization time-of-flight mass spectrometry.  

PubMed

The molar mass parameters for arabino-4-O-methylglucuronoxylans, arabinohexenuronoxylans, 4-O-methylglucuronoxylans, hexenuronoxylans, and galactoglucomannans extracted from wood and pulps have been determined. To characterize different types of hemicelluloses, delignified wood (spruce, pine, larch, aspen, and birch) and chemical pulps (unbleached and totally chlorine-free bleached) were extracted with dimethyl sulfoxide (DMSO) or alkaline aqueous solutions. Size exclusion chromatography (SEC) with off-line matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-MS) were employed to characterize the molar masses. The hemicellulose extracts were separated by SEC into fractions each containing components with a narrow range of molar masses and the average molar mass of each fraction subsequently determined by MALDI-MS. The molar mass parameters for the hemicelluloses were then calculated on the basis of the SEC distribution curves and MALDI-MS spectra. As expected, in most cases the hemicelluloses extracted from wood (holocellulose) exhibited higher molar masses than did the corresponding hemicelluloses from chemical pulps. The molar mass parameters for hemicelluloses isolated from pulps derived from cooking samples of the same batch of softwood chips decreased in the following order: ASAM pulp > MSSAQ pulp > kraft pulp. The lowest molar masses were demonstrated by the glucuronoxylans extracted from pulps obtained by cooking with acidic sulfite. The xylans from bleached kraft pulp were characterized by molar masses that were only slightly lower than those of the corresponding xylans from unbleached pulp. The xylans extracted into DMSO exhibited somewhat lower molar masses than did the corresponding xylans extracted into alkaline aqueous solutions. In all cases the range of molar masses demonstrated by the hemicelluloses investigated was found to be rather narrow, i.e., the polydispersity index Mw/Mn was found to be approximately 1.1-1.4. PMID:11710047

Jacobs, A; Dahlman, O

2001-01-01

251

Pulp-capping with recombinant human insulin-like growth factor I (rhIGF-I) in rat molars.  

PubMed

The aim of this study was to explore pulp healing and reparative dentinogenesis following pulp-capping by using recombinant human insulin-like growth factor I (rhIGF-I). Exposures were made through the mesial pulp horn in first upper molars in two-month-old Wistar rats. The pulp was covered with one dose of sterile 4% methylcellulose gel containing either 400 ng rhIGF-I or saline in contralateral controls. The exposure site was closed with sterile Teflon membrane, and the cavity was filled with IRM cement. Additional molars were capped with Dycal as controls. After 3, 7, or 28 days, animals were anesthetized and fixed by intravascular glutaraldehyde perfusion. Molars were decalcified and processed for histological analysis and cut with membrane and residual methacrylate from IRM in situ. Only specimens with acceptable pulp sealing according to blinded microscopy control were included. On day 3, identical inflammatory responses in the upper pulp were observed in molars with rhIGF-I gel or control gel. On day 7, granulation tissue ingrowth had partly replaced inflammatory infiltration in both groups. After 28 days, complete dentin bridging and tubular dentin formation were observed more frequently and closer to the test substance containing rhIGF-I. The reparative dentin response to capping with rhIGF-I was similar to that after the use of Dycal. In conclusion, microscopic control of membrane sealing in situ gives valid information on the more subtle pulp effects of growth factors. The observations suggest that pulp-capping of rat molars by means of rhIGF-I enhances reparative dentinogenesis in comparison with vehicle controls. PMID:12640754

Lovschall, H; Fejerskov, O; Flyvbjerg, A

2001-08-01

252

Brief communication: A morphometric analysis of the neandertal upper second molar Leuca I.  

PubMed

The scarcity of Neandertal remains from Southern Europe hampers our understanding of Neandertal variability, and can bias interpretations about Neandertal geographic variation. To address this issue, it is often important to reassess human remains that, while discovered decades ago, remain relatively unknown to the scientific community. In this contribution, we provide a complete state-of-the-art comparative morphometric analysis of Leuca I, an unworn left second upper molar (LM(2) ) discovered in 1958 in Bambino's Cave (near Santa Maria di Leuca, Apulia, Italy) and attributed to Homo neanderthalensis. Our study includes comparisons of standard metric and nonmetric data, a 2D image analysis of the occlusal surface and measurements of both 2D and 3D enamel thickness and dental tissue proportions. Although Leuca I follows the Neandertal M(2) s trend in some morphometric aspects (i.e., small relative occlusal polygon area), in other cases it falls to the higher end (for 3D average enamel thickness) or even outside (for 3D-relative enamel thickness) the Neandertal M(2) variability, thus increasing the known Neandertal range of variation. PMID:23999832

Benazzi, Stefano; Bailey, Shara E; Mallegni, Francesco

2013-10-01

253

Endodontic retreatment of a mandibular first molar with five root canal systems: an important clinical lesson.  

PubMed

The objective of root canal treatment is to perform complete debridement of the root canals and subsequent obturation to facilitate healing of periapical pathosis. However, this process becomes complicated with the presence of additional root canal systems. The purpose of the present article is to report successful non-surgical retreatment of a mandibular first molar with five canals. This case report discusses the clinical management of a previously root filled mandibular firstmolar with two missed canal systems; distolingual and an additional mesial canal known as the middle mesial canal. The post-treatment radiographs show successful obturation to length in all canals. The middle mesial canal was found to be associated with mesiolingual canal and categorised as confluent. The configuration of canals in the mesial root was type XV, based on the classification given by Sert and Bayirli. This case report highlights the importance of knowledge and its application in the management of abnormal anatomic variants which play a crucial role in the success of endodontic retreatment. PMID:24654237

Hasan, Muhammad; Umer, Fahad

2014-01-01

254

A 1-year clinical evaluation of fissure sealants on permanent first molars  

PubMed Central

Objective: To evaluate and compare the retention, marginal discoloration, surface texture and anatomical form of pit and fissure sealants. Materials and Methods: Thirty children between the ages of 6 and 10 years, who were attending the school health program regularly, had participated in the study. A split-mouth design was used in which the two fissure sealants (Helioseal-F and Glass ionomer Fuji VII) were randomly placed in 60 matched contralateral pairs of permanent molar teeth. Sealants were rated by a single trained and calibrated examiner using mouth mirrors and probes following the US Public Health Service criteria. The sealants were evaluated at 3 months, 6 months and 1 year intervals. Results: The data obtained for retention, marginal discoloration, surface texture and anatomical form of pit and fissure sealants were tabulated and compared statistically using the Chi-square test of significance. Conclusion: The Helioseal-F sealant was better than the Glass ionomer Fuji VII sealant with respect to retention, anatomical form and surface texture. Both the materials showed similar results with respect to marginal discoloration. PMID:22557898

Ninawe, Nupur; Ullal, Nayak Anand; Khandelwal, Vishal

2012-01-01

255

Comparison of two different flap designs in the surgical removal of bilateral impacted mandibular third molars.  

PubMed

The purpose of this study was to compare the effects of flap design on the postoperative sequelae of pain, swelling, trismus and wound dehiscence after surgical removal of bilateral impacted mandibular third molars (M3). 20 patients aged 20-30 years who required removal of bilateral impacted M3 were included in the study. Maximum interincisal opening and facial measurements were recorded preoperatively. Bayonet flap was used on one side and envelope flap on the other side for the removal of impacted M3. The effect of flap design on pain, swelling, trismus and wound dehiscence was evaluated postoperatively. Pain and wound dehiscence were significantly greater in the envelope flap group compared with the bayonet flap group (P<0.05). No significant difference in postoperative swelling and trismus was found in either group (P>0.05). The bayonet flap was superior to the envelope flap for postoperative pain and wound dehiscence. There was no difference in postoperative swelling and trismus between the two groups. PMID:20727713

Sandhu, A; Sandhu, S; Kaur, T

2010-11-01

256

[Evaluation of the bite block wedged between the maxillary and mandibular molars].  

PubMed

The purpose of this study was to compare our original bite block (T-X Block) wedged between the maxillary and mandibular molars, with the standard gum bite block, in 200 patients whose tracheas were intubated. During emergence from isoflurane anesthesia, no trouble occurred in T-X Block group (n = 100). On the other hand, lip damage and ejection of the bite block were found in 11 and 10 cases, respectively, in gum bite block group (n = 100). As another study, an opening between the maxillary and mandibular incisor edges was measured with T-X Block placed in twenty patients under general anesthesia. The inter-incisal distances in one way of using it as a smaller wedge and in the other way as a bigger one were 21.6 +/- 2.4 and 25.2 +/- 2.6 mm, respectively. Those values were significantly larger than thickness of the gum bite block. T-X Block is very useful because its use causes no complications and makes it easier to insert a naso-gastric tube as well as to clean the oral cavity with suction by giving a larger opening of the mouth. PMID:8997058

Katoh, H; Nishiyama, J; Takiguchi, M; Yamamoto, M; Fujita, K; Yamasaki, Y

1996-12-01

257

Properties of Calcium Phosphate Cements With Different Tetracalcium Phosphate and Dicalcium Phosphate Anhydrous Molar Ratios  

PubMed Central

Calcium phosphate cements (CPCs) were prepared using mixtures of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA), with TTCP/DCPA molar ratios of 1/1, 1/2, or 1/3, with the powder and water as the liquid. Diametral tensile strength (DTS), porosity, and phase composition (powder x-ray diffraction) were determined after the set specimens have been immersed in a physiological-like solution (PLS) for 1 d, 5 d, and 10 d. Cement dissolution rates in an acidified PLS were measured using a dual constant composition method. Setting times ((30 ± 1) min) were the same for all cements. DTS decreased with decreasing TTCP/DCPA ratio and, in some cases, also decreased with PLS immersion time. Porosity and hydroxyapatite (HA) formation increased with PLS immersion time. Cements with TTCP/DCPA ratios of 1/2 and 1/3, which formed calcium-deficient HA, dissolved more rapidly than the cement with a ratio of 1/1. In conclusion, cements may be prepared with a range of TTCP/DCPA ratios, and those with lower ratio had lower strengths but dissolved more rapidly in acidified PLS. PMID:19779581

Hirayama, Satoshi; Takagi, Shozo; Markovic, Milenko; Chow, Laurence C.

2009-01-01

258

Endodontic treatment of mandibular molar with root dilaceration using Reciproc single-file system  

PubMed Central

Biomechanical preparation of root canals with accentuated curvature is challenging. New rotatory systems, such as Reciproc, require a shorter period of time to prepare curved canals, and became a viable alternative for endodontic treatment of teeth with root dilaceration. Thus, this study aimed to report a clinical case of endodontic therapy of root with accentuated dilaceration using Reciproc single-file system. Mandibular right second molar was diagnosed as asymptomatic irreversible pulpitis. Pulp chamber access was performed, and glide path was created with #10 K-file (Dentsply Maillefer) and PathFile #13, #16 and #19 (Dentsply Maillefer) up to the temporary working length. The working length measured corresponded to 20 mm in the mesio-buccal and mesio-lingual canals, and 22 mm in the distal canal. The R25 file (VDW GmbH) was used in all the canals for instrumentation and final preparation, followed by filling with Reciproc gutta-percha cones (VDW GmbH) and AH Plus sealer (Dentsply Maillefer), using thermal compaction technique. The case has been receiving follow-up for 6 mon and no painful symptomatology or periapical lesions have been found. Despite the difficulties, the treatment could be performed in a shorter period of time than the conventional methods. PMID:24010084

Meireles, Daniely Amorin; Bastos, Mariana Mena Barreto; Marques, André Augusto Franco; Sponchiado, Emílio Carlos

2013-01-01

259

Study on Interactions of Continuous Low Power CO2 Laser with Malaysian Molar Teeth  

NASA Astrophysics Data System (ADS)

Recent studies have shown that CO2 lasers can successfully be used at low-energy densities in dentistry. The CO2 laser is effective for a dental hard tissue since it strongly absorbs light in certain regions of the infrared spectrum because of the carbonate and hydroxyl groups in the structure. In this study, nineteen samples of molars extracted human teeth were irradiated with low power CO2 laser. Laser power of 3W, 6W, 9W, 12W, 15W and 18W, with exposure time of 5 s and 10 s, and distance between laser aperture and sample of 4 cm were used. Laser power above 18W is seen to damage the teeth. The teeth compositions were analyzed using the Fourier Transform Infrared Spectroscopy (FTIR). High laser power caused higher reflectance of the beam because the increased in temperature increasing the rate of chemical reaction, hence, the products after the irradiation. This situation can be explained by the Arrhenius equation [1].

Ahmad, A. L.; Jaafar, M. S.; Ramzun, M. R.; Bermakai, M. Yahaya; Ismail, N. E.; Houssien, Hend A. A.

2010-07-01

260

Molar microwear textures and the diets of Australopithecus anamensis and Australopithecus afarensis.  

PubMed

Many researchers have suggested that Australopithecus anamensis and Australopithecus afarensis were among the earliest hominins to have diets that included hard, brittle items. Here we examine dental microwear textures of these hominins for evidence of this. The molars of three Au. anamensis and 19 Au. afarensis specimens examined preserve unobscured antemortem microwear. Microwear textures of these individuals closely resemble those of Paranthropus boisei, having lower complexity values than Australopithecus africanus and especially Paranthropus robustus. The microwear texture complexity values for Au. anamensis and Au. afarensis are similar to those of the grass-eating Theropithecus gelada and folivorous Alouatta palliata and Trachypithecus cristatus. This implies that these Au. anamensis and Au. afarensis individuals did not have diets dominated by hard, brittle foods shortly before their deaths. On the other hand, microwear texture anisotropy values for these taxa are lower on average than those of Theropithecus, Alouatta or Trachypithecus. This suggests that the fossil taxa did not have diets dominated by tough foods either, or if they did that directions of tooth-tooth movement were less constrained than in higher cusped and sharper crested extant primate grass eaters and folivores. PMID:20855308

Ungar, Peter S; Scott, Robert S; Grine, Frederick E; Teaford, Mark F

2010-10-27

261

Molar Cotton-Mouton constants and anisotropy of magnetic susceptibility of benzyl chlorides and benzyl bromides  

SciTech Connect

Based on an analysis of electrical and optical data, they previously established the steric structure of a series of benzyl halides and found that the polarizability ellipsoid of the aromatic nucleus undergoes significant rearrangement of its semiaxes in comparison to the semiaxes in toluene (I). In all of the systems examined the mobility of the electron cloud in the plane of the ring increases and decreases in the perpendicular direction. A conformation is realized in which the benzene ring is close to shielding of the C-H bond. Hyperconjugation of the ..pi..arom-sigmaC-Hal* type, particularly manifested in the nuclear quadrupole resonance spectra, is apparently responsible for the observed effects. The effect of similar interactions on the magnetic properties has not been studied either experimentally or theoretically. The anisotropies of magnetic susceptibility of molecules or groups of atoms can be calculated from the known optical polarizabilities using data on the magnetic birefringence constant (the Cotton-Mouton effect) of compounds in the form of vapors or solutions. The molar Cotton-Mouton constants of the title compounds were measured and the magnetic susceptibility ellipsoids (MSE) of the C/sub 6/H/sub 5/-C fragment in benzyl halides and (I), whose MSe is known, were comparatively estimated in the present study.

Vul'fson, S.G.; Dianova, O.M.; Vereshchagin, A.N.

1987-01-10

262

Subjective and objective evaluation of low-level laser therapy after molar extraction  

NASA Astrophysics Data System (ADS)

The aim of this study was to evaluate the different frequencies of low-level laser radiation on healing process after human molar extractions. Frequencies of 5 Hz, 292 Hz and 9000 Hz were used in experiments. Monitoring of secretory IgA and albumin level in saliva and changes in bone density were used as objective markers of biostimulatory effect. Subjective evaluation of therapy was observed using scale. Changes of sIgA, albumin levels and bone density were compared in group of 150 patients. Differences in levels of the saliva markers were found to be significant comparing irradiated and non-irradiated groups, as well as comparing groups irradiated by various modulatory frequencies. We observed significant differences between the increase of sIgA res. Albumin and subjective treatment feelings. Bone density after extraction and six-months after surgical treatment was examined using the dental digital radiovisiography. There were detected no significant differences between bone density in irradiated and non- irradiated groups perhaps due to our used therapy diagram.

Kucerova, Hana; Dostalova, Tatjana; Himmlova, Lucia; Bartova, Jirina; Mazanek, Jiri

2000-06-01

263

Coupled Nanomechanical and Raman Microspectroscopic Investigation of Human Third Molar DEJ  

PubMed Central

The dentino-enamel junction (DEJ) connects enamel, that covers the outer surface of a tooth, to a thicker underlying dentin. The DEJ is a critical interface that permits joining these materials that have widely dissimilar mechanical properties. AFM-based nanoindentation and Raman microspectroscopy were used to define the width and composition of human molar DEJ. Indentation elastic modulus and hardness of enamel, dentin, and DEJ were determined along lines of indents made at 2??m intervals across the DEJ. Indents made at maximum loads at each end of the indent lines were used to make visible markers allowing Raman microspectroscopy at 1??m intervals across the DEJ, while using the nanoindent markers for orientation and location. Functional DEJ width estimates were made based on results from nanoindentation and Raman microspectroscopy. DEJ width estimates ranged from 4.7 (±1.2) ?m to 6.1 (±1.9) ?m based on hardness and 4.9 (±1.1) ?m to 6.9 (±1.9) ?m based on modulus. DEJ width based on Raman peak intensity variations were 8.0 (±3.2) ?m to 8.5 (±3.1) ?m based on the phosphate peak, and 7.6 (±3.2) ?m to 8.0 (±2.6) ?m for C–H stretching mode. These estimates are in the range of DEJ width estimates reported using nanoindentation. PMID:20948572

Gallagher, R. R.; Balooch, M.; Balooch, G.; Wilson, R. S.; Marshall, S. J.; Marshall, G. W.

2010-01-01

264

Evaluation of dexamethasone for reduction of postsurgical sequelae of third molar removal.  

PubMed

Sixty patients with bilaterally symmetrical impacted third molars participated in this double-blind, within-subject study to quantify the effects of 4 mg of dexamethasone on reducing postsurgical sequelae. Each patient's surgery was staged by mouth side and completed in two appointments 5 to 6 weeks apart. A preoperative dose of dexamethasone given intravenously was randomized to mouth side and surgical appointment; sterile water served as a control. Major areas assessed in this study were facial swelling, pain, and trismus. No difference in swelling and daily pain was noted. However, trismus and global pain were significantly affected by the steroid. Patients had a daily postsurgical increase in incisal opening of 4 to 6 mm over the control side during the examination period. Patients evaluated pain by choosing the least painful side. By a greater than 4:1 margin, patients chose the steroid side as the least painful side. No increase in the rate or type of complications was detected between control and steroid sides. PMID:1403273

Neupert, E A; Lee, J W; Philput, C B; Gordon, J R

1992-11-01

265

Densities, Excess Molar Volumes, and Thermal Expansion Coefficients of Aqueous Aminoethylethanolamine Solutions at Temperatures from 283.15 to 343.15 K.  

PubMed

The densities of aqueous mixtures of aminoethylethanolamine (CAS #000111-41-1) were measured over the entire compositional range at temperatures of 283.15-343.15 K. The results of these measurements were used to calculate excess molar volumes and isobaric thermal expansion coefficients, and partial molar and apparent molar volumes and excess isobaric thermal expansion coefficients were subsequently derived. The excess molar volumes were correlated as a function of the mole fraction using the Redlich-Kister equation. Temperature dependences of the Redlich-Kister coefficients are also presented. The partial molar volumes at infinite dilution of AEEA in water were determined using two different methods. In addition, the solution density was correlated using a Joubian-Acree model. Aqueous solutions of AEEA exhibit similar properties to the aqueous solutions of other alkanolamines (like monoethanolamine) used in acid gas sweetening. PMID:24899753

Stec, Marcin; Tatarczuk, Adam; Spiewak, Dariusz; Wilk, Andrzej

2014-01-01

266

An unusual maxillary molar with four roots and four buccal canals confirmed with the aid of spiral computed tomography: a case report.  

PubMed

This case report describes an endodontically managed maxillary first molar with an unusual morphology of five canals. Maxillary first molar has one of the most complex root and canal anatomy. The greatest variations observed are the presence of two canals in the mesiobuccal root of maxillary molar, canals in the furcation area and the presence of lateral and accessory canals. The incidence of two distobuccal canals in itself is quite rare. A literature search revealed only a few case reports of four buccal canals in maxillary first molars. This case report presents the successful root canal treatment of the maxillary first molar with four roots and five canals. The use of spiral computed tomography scan in this case greatly contributed towards confirming this rare morphology. PMID:25214739

Sharma, Ritu; Maroli, Kriti; Sinha, Nidhi; Singh, Bijay

2014-07-01

267

An Unusual Maxillary Molar with Four Roots and Four Buccal Canals Confirmed with the Aid of Spiral Computed Tomography: A Case Report  

PubMed Central

This case report describes an endodontically managed maxillary first molar with an unusual morphology of five canals. Maxillary first molar has one of the most complex root and canal anatomy. The greatest variations observed are the presence of two canals in the mesiobuccal root of maxillary molar, canals in the furcation area and the presence of lateral and accessory canals. The incidence of two distobuccal canals in itself is quite rare. A literature search revealed only a few case reports of four buccal canals in maxillary first molars. This case report presents the successful root canal treatment of the maxillary first molar with four roots and five canals. The use of spiral computed tomography scan in this case greatly contributed towards confirming this rare morphology. PMID:25214739

Sharma, Ritu; Maroli, Kriti; Sinha, Nidhi; Singh, Bijay

2014-01-01

268

Influence of citric acid molar ratio on the sintering behavior of nanocrystalline BaCe0.8Sm0.2O(3-delta).  

PubMed

The samarium-doped barium cerate (BaCe0.8Sm0.2O(3-delta), BCS) nano crystalline powders were synthesized via citric-nitrate method. The BCS nanopowders were prepared with various molar ratio of citric acid to metal nitrate. The pure perovskite structure was obtained from the BCS calcinated at 1200 degrees C and its crystalline size was increased with increase of the molar ratio citric acid to metal nitrate, while the aggregated particle size was significantly decreased as increasing the molar ratio. Also, excellent densification behavior was observed when high molar ratio of citric acid to metal nitrate was used. It was clarified that the molar ratio of citric acid determines the aggregated particle size and, in turn, finial microstructure after sintering. PMID:24734634

Park, Inyu; Kim, Jeongin; Choi, Jinyi; Lee, Hunhyeong; Park, Jonghun; Shin, Dongwook

2014-05-01

269

Structural and Ultra-Structural Features of the First Mandibular Molars of Young Rats Submitted to Pre and Postnatal Protein Deficiencies  

PubMed Central

The effects of protein malnutrition, both in utero and prior to weaning, on formation of the first mandibular molars were evaluated by phase-contrast and electron microscopy in rats. The nourished group (GI) received a diet that included 20% casein, while the malnourished group (GII) received 5% casein. The first mandibular molars from GII exhibited low density of cells and odontoblasts, which lacked regular organization compared with molars from GI. In addition, a difference in collagen type was observed between the groups, with a prevalence of Type III collagen fibers detected in the dentin, periodontal ligament, and alveolar bone of GII, and a prevalence of Type I collagen fibers in GI. Finally, examination of surface area in molar sagittal sections indicated 30% less dentin in GII, compared with GI. Our results suggest that structural and ultra-structural features of the dentin-pulp complex and periodontal components of rat molars are affected by protein deficiency. PMID:19557153

Gonçalves, L.A; Boldrini, S.C; Capote, T.S.O; Binotti, C.B; Azeredo, R.A; Martini, D.T; Rosenberg, B; Bautz, W.G; Liberti, E.A

2009-01-01

270

Molar mass profiling of synthetic polymers by free-solution capillary electrophoresis of DNA-polymer conjugates.  

PubMed

The molar mass distribution of a polymer sample is a critical determinant of its material properties and is generally analyzed by gel permeation chromatography or more recently, by MALDI-TOF mass spectrometry. We describe here a novel method for the determination of the degree of polymerization of polydisperse, uncharged, water-soluble polymers (e.g., poly(ethylene glycol) (PEG)), based upon single-monomer resolution of DNA-polymer conjugates by free-solution capillary electrophoresis. This is accomplished by end-on covalent conjugation of a polydisperse, uncharged polymer sample (PEG) to a monodisperse, fluorescently labeled DNA oligomer, followed by electrophoretic analysis. The monodisperse, charged DNA "engine" confers to each conjugate an equal amount of electromotive force, while the varying contour lengths of the uncharged, polydisperse polymers engender different amounts of hydrodynamic drag. The balance of electromotive and hydrodynamic forces enables rapid, high-resolution separation of the DNA-polymer conjugates as a function of the size of the uncharged PEG tail. This provides a profile of the molar mass distribution of the original polymer sample that can be detected by laser-induced fluorescence through excitation of the dye-labeled DNA. We call this method free solution conjugate electrophoresis (FSCE). Theory-based analysis of the resulting electrophoresis data allows precise calculation of the degree of polymerization of the PEG portion of each conjugate molecule. Knowledge of the molecular mass of the uncharged polymer's repeat unit allows for direct calculation of the molar mass averages as well as sample polydispersity index. The results of these analyses are strikingly reminiscent of MALDI-TOF spectra taken of the same PEG samples. PEG samples of 3.4-, 5-, and 20-kDa nominal average molar mass were analyzed by FSCE and MALDI-TOF; the values of the molar mass averages, Mw and Mn, typically agree to within 5%. Measurements and molar mass calculations are performed without any internal standards or calibration. Moreover, when DNA-polymer conjugate analysis is performed in a chip-based electrophoresis system, separation is complete in less than 13 min. FSCE offers an alternative to MALDI-TOF for the characterization of uncharged, water-soluble polymers that can be uniquely conjugated to DNA. PMID:11338593

Vreeland, W N; Desruisseaux, C; Karger, A E; Drouin, G; Slater, G W; Barron, A E

2001-04-15

271

Stability of ingested methylcellulose in the rat determined by polymer molar mass measurements by light scattering.  

PubMed

Methylcellulose (MC) is ingested by humans in food and pharmaceutical formulations. The functional properties of MC like those of other linear polymers depend primarily on polymer length or molar mass for largely linear polymers. Although many studies in animals and humans have shown complete excretion of MC, in vitro human fecal fermentation studies indicate that MC can be degraded and presumably lose some of its functionality. In this study, MC polymer distribution in the feces from rats fed a diet containing 8% methylcellulose were compared to the fed MC. The water-soluble polymers in the feces were separated by a size exclusion chromatography (SEC) and the polymer distributions determined by multiple angle laser light scattering (MALLS). Detection of the fluorescent MC-calcofluor complex was used to confirm the identity of the eluting MC peak. All dietary MC was recovered in the feces. There is a small shift (P < 0.06) in the weight-averaged molecular weight of polymer distribution of MC extracted from the feces to 2.71 +/- 0.15 x 10(5) g/mol from 3.15 +/- 0.02 x 10(5) g/mol in the standard. There is also an increase in the polydispersity from 1.21 in the standard to 1.8 in the fecal extract. The distribution of the substituted methoxylated glucose monomers by gas chromatography also confirms the stability of MC fed to rats. The amount of actual hydrolysis is estimated to be about 0.1 glycosidic linkage/molecule. MC is not easily determined by standard dietary fiber methods, and SEC with MALLS and/or fluorescence may be a useful alternative. PMID:12475296

Yokoyama, Wallace H; Knuckles, Benny E; Davis, Paul A; Daggy, Bruce P

2002-12-18

272

Impacted third molars in sagittal split osteotomies in mandibular prognathism and micrognathia  

PubMed Central

Background: The timing of removal of mandibular third molars (M3) in Sagittal Split Osteotomy (SSO) has been an issue of contention. The aim of this retrospective study is to identify the incidence of unfavorable fractures during SSO with the presence of M3 and to identify the association between unfavorable fractures with the factors specifically related to the M3. Materials and Methods: Retrospective analysis of consecutive bilateral sagittal split osteotomy (BSSO) patient's treatment records of 208 patients treated by a single surgeon was analyzed. The position of M3, fracture details, and demographics were collected. Descriptive statistics and Chi-square tests were employed in SPSS package. A P ? 0.05 was taken as significant. Results: There were altogether 416 SSO performed. M3 was completely impacted in 88.9% of all instances, and in 85.6% of the instances, the bulk of the M3 was identified to be above the external oblique ridge. In 59.4% of the cases, M3 was positioned in alignment with the arch as observed during surgery. There were about 27 (6.5%) instances of unfavorable splits. A statistically significant relationship was observed with M3 root morphology and axial position of M3. Discussion: This study for the first time has confirmed the spatial positioning of M3 as one of the several causes of unfavorable splits during SSO. An impacted M3 that lies below the oblique ridge, distoangularly/vertically oriented, with divergent/supernumerary root would cause unfavorable splits when the spreader is not used properly. Potential causes and influencing factors of the unfavorable splits are discussed. PMID:24987597

Balaji, S. M.

2014-01-01

273

Relationship between hydroperoxide concentration and average molar mass in thermo-oxidized polyethylene  

NASA Astrophysics Data System (ADS)

The aim of this research project is to investigate the oxidation mechanism of high density polyethylene (HDPE) used in outdoor applications, in order to establish in a near future, a non-empirical kinetic model for lifetime prediction. The present paper focuses on the changes in the hydroperoxide (POOH) concentration induced by thermo-oxidative ageing, and on their relationship with the evolution of the weight average molar mass (Mw) due both to chain scission and crosslinking processes. Thin HDPE films were aged at 110 and 140°C in air under atmospheric pressure. In a first part, changes in the POOH concentration versus ageing time were assessed by three different analytical methods previously reported in the literature: modulated differential scattering calorimetry (MDSC), Fourier transform Infra-Red spectrometry after chemical derivatization treatment with gaseous sulfur dioxide (SO2-FTIR), and iodometry. A comparison of experimental results revealed that these three methods provide very similar quantitative data on POOH accumulation, whereas iodometry tends to strongly underestimate the subsequent stage of POOH decomposition. It was thus suspected that iodometry does not only titrate POOH, but also other chemical species (presumably double bonds) formed when POOH decompose. Therefore, only MDSC and SO2-FTIR were considered as relevant methods for POOH titration. In a second part, changes in Mw versus ageing time were monitored by size exclusion chromatography (SEC). A sharp drop of Mw was first observed at the beginning of exposure, which was assigned to an intensive chain scission process. Then, in a second stage, a stabilization or even a substantial re-increase in Mw was observed, suggesting a competition between chain scission and crosslinking processes. As this second stage starts at the same time as POOH decomposition, it was concluded that there is a strong correlation between both phenomena, occurring respectively at the macromolecular and molecular scales.

Da Cruz, Manuela; Van Schoors, Laetitia; Colin, Xavier; Benzarti, Karim

2014-05-01

274

How to measure and predict the molar absorption coefficient of a protein.  

PubMed Central

The molar absorption coefficient, epsilon, of a protein is usually based on concentrations measured by dry weight, nitrogen, or amino acid analysis. The studies reported here suggest that the Edelhoch method is the best method for measuring epsilon for a protein. (This method is described by Gill and von Hippel [1989, Anal Biochem 182:319-326] and is based on data from Edelhoch [1967, Biochemistry 6:1948-1954]). The absorbance of a protein at 280 nm depends on the content of Trp, Tyr, and cystine (disulfide bonds). The average epsilon values for these chromophores in a sample of 18 well-characterized proteins have been estimated, and the epsilon values in water, propanol, 6 M guanidine hydrochloride (GdnHCl), and 8 M urea have been measured. For Trp, the average epsilon values for the proteins are less than the epsilon values measured in any of the solvents. For Tyr, the average epsilon values for the proteins are intermediate between those measured in 6 M GdnHCl and those measured in propanol. Based on a sample of 116 measured epsilon values for 80 proteins, the epsilon at 280 nm of a folded protein in water, epsilon (280), can best be predicted with this equation: epsilon (280) (M-1 cm-1) = (#Trp)(5,500) + (#Tyr)(1,490) + (#cystine)(125) These epsilon (280) values are quite reliable for proteins containing Trp residues, and less reliable for proteins that do not. However, the Edelhoch method is convenient and accurate, and the best approach is to measure rather than predict epsilon. PMID:8563639

Pace, C. N.; Vajdos, F.; Fee, L.; Grimsley, G.; Gray, T.

1995-01-01

275

Molar mass, entanglement and associations of the biofilm polysaccharide of Staphylococcus epidermidis  

PubMed Central

Biofilms are microbial communities that are characterized by the presence of a viscoelastic extracellular polymeric substance (EPS). Studies have shown that polysaccharides, along with proteins and DNA, are a major constituent of the EPS, and play a dominant role in mediating its microstructure and rheological properties. Here, we investigate the possibility of entanglements and associative complexes in solutions of extracellular polysaccharide intercellular adhesin (PIA) extracted from Staphylococcus epidermidis biofilms. We report that the weight average molar mass and radius of gyration of PIA isolates are 2.01 × 105 ± 1200 g/mol and 29.2 ± 1.2 nm respectively. The coil overlap concentration, c*, was thus determined to be (32 ± 4) × 10?4 g/mL. Measurements of the in situ concentration of PIA (cPIA,Biofilm) was found to be (10 ± 2) × 10?4 g/mL. Thus, cPIA,Biofilm < c* and the amount of PIA in the biofilm is too low to cause polymer chain entanglements. In the pH range 3.0 to 5.5, PIA was found to both self-associate and to form complexes with bovine serum albumin (BSA). By static light scattering, both self-association and complex formation with 0.5 %(w/v) BSA were found to occur at PIA concentrations of 0.30 × 10?4 g/mL and greater, which is about 30 times lower than the measured cPIA,Biofilm. These results suggest that the microscopic origin of EPS viscoelasticity is unlikely to be due to polysaccharide entanglements. Furthermore, the onset of self-association and protein complexation of PIA occurs at concentrations far lower than the native PIA concentration in biofilms. This finding therefore suggests a critical role for those two association mechanisms in mediating biofilm viscoelasticity. PMID:23540609

Ganesan, Mahesh; Stewart, Elizabeth J.; Szafranski, Jacob; Satorius, Ashley; Younger, John G.; Solomon, Michael J.

2013-01-01

276

Elevated Serum 25(OH)-Vitamin D Levels Are Negatively Correlated with Molar-Incisor Hypomineralization.  

PubMed

To date, the precise etiology of molar-incisor hypomineralization (MIH) is uncertain. Vitamin D plays a key role in hard tissue formation. Therefore, this study aimed to analyze the relationship between serum 25-hydroxy-vitamin D (25(OH)D) status and dental health data obtained from 1,048 children in a 10-year follow-up of the Munich GINIplus and LISAplus birth cohorts. The dental examination included the diagnosis of MIH and recording of (non-)cavitated caries lesions in primary and permanent teeth. Serum 25(OH)D concentrations were taken from blood samples of the 10-year investigation and measured with a fully automated, modular system. Different logistic regression and Poisson hurdle models were calculated. MIH was diagnosed in 13.6% of the study population. Approximately 16.4% of the children demonstrated caries-related defects (D3-4MFS > 0). The mean season-adjusted concentration of 25(OH)D was 75.8 nmol/l (standard deviation 22.0 nmol/l). After adjusting for sex, age, body mass index, parental education, equivalent income, and television/personal computer (TV/PC) viewing hours, a 10 nmol/l increase in serum 25(OH)D concentrations was significantly associated with a lower odds ratio of having MIH (OR = 0.89; P = 0.006). Furthermore, higher 25(OH)D values were associated with a lower number of caries-affected permanent teeth. It is concluded that elevated serum 25(OH)D concentrations were associated with better dental health parameters. PMID:25503610

Kühnisch, J; Thiering, E; Kratzsch, J; Heinrich-Weltzien, R; Hickel, R; Heinrich, J

2015-02-01

277

Using occlusal wear information and finite element analysis to investigate stress distributions in human molars  

PubMed Central

Simulations based on finite element analysis (FEA) have attracted increasing interest in dentistry and dental anthropology for evaluating the stress and strain distribution in teeth under occlusal loading conditions. Nonetheless, FEA is usually applied without considering changes in contacts between antagonistic teeth during the occlusal power stroke. In this contribution we show how occlusal information can be used to investigate the stress distribution with 3D FEA in lower first molars (M1). The antagonistic crowns M1 and P2–M1 of two dried modern human skulls were scanned by ?CT in maximum intercuspation (centric occlusion) contact. A virtual analysis of the occlusal power stroke between M1 and P2–M1 was carried out in the Occlusal Fingerprint Analyser (OFA) software, and the occlusal trajectory path was recorded, while contact areas per time-step were visualized and quantified. Stress distribution of the M1 in selected occlusal stages were analyzed in strand7, considering occlusal information taken from OFA results for individual loading direction and loading area. Our FEA results show that the stress pattern changes considerably during the power stroke, suggesting that wear facets have a crucial influence on the distribution of stress on the whole tooth. Grooves and fissures on the occlusal surface are seen as critical locations, as tensile stresses are concentrated at these features. Properly accounting for the power stroke kinematics of occluding teeth results in quite different results (less tensile stresses in the crown) than usual loading scenarios based on parallel forces to the long axis of the tooth. This leads to the conclusion that functional studies considering kinematics of teeth are important to understand biomechanics and interpret morphological adaptation of teeth. PMID:21615398

Benazzi, Stefano; Kullmer, Ottmar; Grosse, Ian R; Weber, Gerhard W

2011-01-01

278

Antimicrobial effect of ozonated water, sodium hypochlorite and chlorhexidine gluconate in primary molar root canals  

PubMed Central

Objective: The aim was to determine the antimicrobial effect of ozonated water, ozonated water with ultrasonication, sodium hypochloride and chlorhexidine (CHX) in human primary root canals contaminated by Enterococcus faecalis (E. faecalis). Materials and Methods: Fifty-eight extracted human primary molar teeth were used. Crowns were cut off using a diamond saw under water-cooling. One hundred roots were obtained and mechanically prepared. The roots were then sterilized by autoclaving in water for 15 min at 121°C. All samples were contaminated with E. faecalis for 24 h and the root canals were randomly divided into five groups (n = 20). Group I: 25 mg/L of Ozonated water (O3aq), Group II: 25 mg/L of O3aq with ultrasonication, Group III: 2.5% Sodium hypochloride (NaOCl), Group IV: 2% CHX and Group V: Positive control. The canal of each specimen was irrigated for 4 min and positive control was untreated. All root canals were agitated with sterile saline solution. The saline solution was collected from canals with sterile paper points. For each specimen, the paper points were transposed to eppendorf vials containing 2 ml of brain heart infusion. According to bacterial proliferation, the mean values of optical density were achieved by EL?SA (Biotek EL ×800, Absorbance Microplate Reader, ABD) and the data were analyzed. Results: NaOCI, CHX and two types of O3aq were found statistically different than positive control group. NaOCI irrigation was found significantly most effective. Conclusions: NaOCl, CHX and O3aq applications provide antibacterial effect in vitro conditions in primary root canals. PMID:25512726

Goztas, Zeynep; Onat, Halenur; Tosun, Gul; Sener, Yagmur; Hadimli, Hasan Huseyin

2014-01-01

279

Cone Beam Computed Topographic Evaluation and Endodontic Management of a Rare Mandibular First Molar with Four Distal Canals  

PubMed Central

Root canal system is complex to understand because of its unpredictable nature. It differs for different teeth and for the same teeth in different individuals. Successful endodontic therapy thus depends on the clinician's ability to anticipate and look for these variations. A mandibular first molar with six root canals represents a rare anatomical variant, particularly when four canals are found in distal root. This case report discusses successful nonsurgical endodontic management of two-root mandibular first molar with four distal canals and two mesial canals reported for the first time in Indian population. Cone beam computed tomography was used as a diagnostic method to confirm the position and presence of 4 root canals in the distal root. PMID:25525525

Sinha, Nidhi; Singh, Bijay; Langaliya, Akshay; Mirdha, Nitin; Huda, Irfanul

2014-01-01

280

Report of a Rare Case: A Maxillary First Molar with Seven Canals Confirmed with Cone-Beam Computed Tomography  

PubMed Central

Introduction: Coronal anatomic variations in permanent maxillary molars are unusual; conversely variations involving the number of root canals or number of roots are more common. Methods and Materials: This case report presents a successful nonsurgical endodontic therapy of left maxillary first molar with three roots and seven root canals. This unusual morphology was diagnosed using a dental operating microscope (DOM) and confirmed with the help of cone-beam computed tomography (CBCT) images. Results: CBCT axial images showed that both of the palatal and distobuccal roots had Vertucci type II canal pattern, whereas the mesiobuccal root canal showed a Sert and Bayirli’s type XV configuration. Conclusion: The use of a DOM and CBCT imaging in endodontically challenging cases can facilitate a better understanding of the complex root canal anatomy, which ultimately enables the clinician to explore the root canal system, and therefore treat it far more efficiently. PMID:24688587

Kumar, Rahul

2014-01-01

281

Molar pregnancy after tubal ligation in a patient with neuroendocrine tumour: when a rare condition coincides with an unexpected diagnosis.  

PubMed

A 40-year-old woman with a history of bilateral tubal ligation and a recent diagnosis of metastatic neuroendocrine tumour in the liver presented with severe nausea, vomiting, diarrhoea and dehydration. She had an inconclusive urine pregnancy test in the emergency department that was followed by an extremely high serum ?-human chorionic gonadotropin. Transvaginal ultrasound, MRI and subsequent pathology from a dilation and curettage (D&C) revealed that the patient had a complete molar pregnancy. This is a case of an unusual patient who reminds us that one person can have a rare diagnosis and an unexpected obstetrical outcome. We could find no evidence in the medical literature of a causal link between these two diagnoses but present this case report of a reproductive age woman with neuroendocrine tumour and complete molar pregnancy. This case also serves as an example of the phenomenon of the 'hook effect.' PMID:24789159

Semenya, Afi Mansa; Roberts, Caroline; Mounsey, Anne

2014-01-01

282

Absence of multiple premolars and ankylosis of deciduous molar with cant of the occlusal plane treated using skeletal anchorage.  

PubMed

ABSTRACT Ankylosis and the absence of premolars are two relatively common conditions encountered in the field of orthodontics. However, the absence of multiple premolars, particularly two adjacent premolars, along with ankylosis of deciduous teeth, is unusual. Herein, we present a case report and discuss some aspects related to these abnormalities. A 15-year-old boy was missing the upper right first and second premolars and the lower right and left second premolars. In addition, the deciduous lower left second molar was ankylosed and in infraocclusion, causing canting of the occlusal plane. The patient was treated with a mini-implant to correct the Class II malocclusion on the left side and a miniplate to correct the cant of the occlusal plan. After treatment, the upper right space was kept closed, with the canine in contact with the first molar, and the lower left space was opened to an implant-prosthetic rehabilitation. PMID:24901068

Farret, Marcel M; Farret, Milton M B

2015-01-01

283

The role of cone beam computed tomography in the endodontic management of a mandibular first molar with three distal canals  

PubMed Central

The presence of three root canals in the distal root of the mandibular first permanent molars is rare; based on in vitro studies its incidence is reported to be between 0.2% and 3%. With the advent of cone beam computed tomography (CBCT) as an adjunctive diagnostic aid, the determination of root canal anatomy in teeth with extra canals and complex canal configurations has become more precise. CBCT provides three dimensional visualization of the pulp canal space, allowing the clinician in determining the spatial relationships of the root canals with each other at various cross sectional levels along the length of the root. The present report discusses the endodontic management of a mandibular first permanent molar with three canals in the distal root, employing CBCT as an adjunctive diagnostic aid to conventional radiography.

Kaushik, Aishvarya; Talwar, Sangeeta; Yadav, Seema; Chaudhary, Sarika; Nawal, Ruchika Roongta

2014-01-01

284

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

PubMed Central

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

2014-01-01

285

Low-temperature heat capacity and standard molar enthalpy of formation of 9-fluorenemethanol (C 14H 12O)  

Microsoft Academic Search

Low-temperature heat capacities of the 9-fluorenemethanol (C14H12O) have been precisely measured with a small sample automatic adiabatic calorimeter over the temperature range between T=78 K and T=390 K. The solid–liquid phase transition of the compound has been observed to be Tfus=(376.567±0.012) K from the heat-capacity measurements. The molar enthalpy and entropy of the melting of the substance were determined to

You-Ying Di; Zhi-Cheng Tan; Xiao-Hong Sun; Mei-Han Wang; Fen Xu; Yuan-Fa Liu; Li-Xian Sun; Hong-Tao Zhang

2004-01-01

286

High-molar-mass hyaluronan degradation by Weissberger's system: Pro and anti-oxidative effects of some thiol compounds  

Microsoft Academic Search

Pro- and anti-oxidative effects of two thiol compounds, d-penicillamine and reduced l-glutathione, on the kinetics of degradation of high-molar-mass hyaluronan samples were monitored via rotational viscometry. The degradation was induced under aerobic condition by the so-called Weissberger?s system [ascorbate plus Cu(II)]. Electron paramagnetic resonance spectroscopy was used to confirm the presence of free radicals generated during the biopolymer degradation. Infrared

Eva Hrabárová; Katarína Valachová; Jozef Rychlý; Peter Rapta; Vlasta Sasinková; Marta Malíková; Ladislav Šoltés

2009-01-01

287

Effect of traumatic occlusion on CGRP and SP immunoreactive nerve fibre morphology in rat molar pulp and periodontium.  

PubMed

Traumatic occlusion provides a trauma that affects the whole tooth and its supporting tissues. To study the effect of this trauma on CGRP and SP immunoreactive nerve morphology in pulp and periodontium, traumatic occlusion was induced in 2-months-old rats. The occlusal surface of the first maxillary molar in 30 rats were unilaterally raised 1 mm with a composite material. At different observation periods up to 30 days, the rats were transcardiacally perfused, the jaws demineralized, sectioned and processed for immunohistochemistry with the avidin-biotin-peroxidase method. Changes in nerve morphology, distribution and density in first and second molars and their supporting tissues were analyzed and compared in experimental (n = 30) and control rats (n = 14). Already after 5 days with traumatic occlusion, 22% of the experimental teeth had increased density of CGRP and SP immunoreactive nerves locally in gingiva, the periodontal ligament and the pulp, while in 15%, axonal proliferation and changed nerve morphology were found in the whole pulp (severe reaction). During a 20-day period, the pulpal nerve reactions progressed and included the whole pulp in 46% of the experimental teeth. The periodontal nerve responses were still localized only to the cervical and apical regions, and they remained local in these areas throughout the experimental periods. After 20 days the number of teeth with severe nerve changes seemed to decrease. The study shows that an unilateral change in occlusion of the first molar initiate nerve responses in the total molar dentition. In this experimental model the pulpal axons containing CGRP and SP reacted more serious to occlusal trauma than the nerves in the periodontium. The results indicate that the nerve changes in some cases might be transient. PMID:1373126

Kvinnsland, I; Heyeraas, K J

1992-01-01

288

Comparison of the influence of ozone and laser therapies on pain, swelling, and trismus following impacted third-molar surgery.  

PubMed

This study aims to evaluate the efficacy of the ozone and laser application in the management of pain, swelling, and trismus after third-molar surgery. Sixty consecutive patients with asymptomatic impacted mandibular third molars were recruited into the study. Patients were randomized into three treatment groups of 20 patients each: two study groups (group 1?=?low-level laser therapy (LLLT), group 2?=?ozone therapy) and a control group (no-LLLT or ozone therapy). Twenty teeth extractions were performed in each group. Evaluations of postoperative pain, the number of analgesics tablets taken, trismus, swelling, and quality of life (Oral Health Impact Profile-14 questionnaire) were made. The sample consisted of 28 female and 32 male patients, whose total mean age was 23.5?±?3.4 (range, 18-25)?years. The pain level and the number of analgesics tablets taken were lower in the ozonated and LLLT applied groups than in the control group. This study showed that ozone and low power laser therapies had a positive effect on the patients' quality of life. Trismus in the LLLT group was significantly less than in the ozonated and control groups (p?=?0.033). Ozone application showed no superiority in regards of postoperative swelling; however, LLLT group had significantly lower postoperative swelling. This study demonstrates that ozone and laser therapies are useful for the reduction of postoperative pain and they increase quality of life after third-molar surgery. Although the ozone therapy had no effect on postoperative swelling and trismus after surgical removal of impacted lower third molars, LLLT had a positive effect. PMID:23494104

Kazancioglu, Hakki Oguz; Ezirganli, Seref; Demirtas, Nihat

2014-07-01

289

Inhibition of secondary cartilage of the intermaxillary suture in Sprague-Dawley rats following the enucleation of maxillary molars  

SciTech Connect

A single craniofacial suture can undergo several morphologic transformations during its development. From 3 to 7 weeks of age, the intermaxillary suture of the rat is synchondrotic in character, featuring secondary cartilage; at later times, this suture is syndesmotic in character, featuring a fibrous tissue interface. Since intermittent mechanical stimulation has been reported to initiate secondary cartilage formation, a study was done to determine if the functioning dentition were responsible for secondary cartilage formation in the intermaxillary suture of the rat. Twenty-two female Sprague-Dawley rats were used. At 3 weeks of age, prior to eruption, the maxillary molars were enucleated from nine animals. Body weights were recorded weekly. Animals were sacrificed weekly from 4 to 7 weeks of age. One hour prior to sacrifice, each rat was injected with (/sup 35/S)sulfate at a dosage of 2 microCi/g body weight. The tissues were evaluated by light microscopy and autoradiography. In the experimental group, the midpalatal suture did not undergo the normal synchondrotic transformation. Instead, this suture remained fibrous with negligible metachromatic staining. In the control animals, the peak period of (/sup 35/S)sulfate incorporation was 4 weeks of age and was five times greater than in the experimental group. The primary stimulus for the initiation of secondary cartilage formation in the midpalatal suture of the rat was molar function. Also, functioning molars were found to be important in the maintenance of the palatal bone.

Forbes, D.P.; Al-Bareedi, S.

1986-01-01

290

Usefulness of mandibular third molar coronectomy assessed through clinical evaluation over three years of follow-up.  

PubMed

The aim of this study was to investigate the 3-year morbidity of coronectomy of the lower third molar and to monitor the behaviour and migration pattern of the retained roots postoperatively. A total of 92 patients (111 teeth) who had undergone a coronectomy between October 2005 and July 2009 were investigated. Patients were followed up at 3 months and 1, 2, and 3 years for clinical evaluation and dental computed tomography imaging of the coronectomy sites. In total, 10 cases (9%) required tooth root extraction within the 3 years after coronectomy. In seven of them, the distal pocket of the lower second molars remained connected to the roots within the first year. Of the cases in whom a pocket did not remain at an early stage, none showed peri-apical lesions on transmission images of the retained roots in the apical area, which usually result from necrosis of the pulp. Root migration increased in the first 2 years after coronectomy but stabilized between the second and third years. In addition, a significant difference was noted in root migration between patients of different ages and sex. Retained roots after coronectomy in the lower third molars led to no complications in terms of infection or the development of pathologies within the first 3 years postoperatively. PMID:25457826

Kohara, K; Kurita, K; Kuroiwa, Y; Goto, S; Umemura, E

2015-02-01

291

Mandibular third molar impactions in male adults: Relationship of Operative time and Types of impaction on inflammatory complications  

PubMed Central

Background: This paper investigates the relationship betweendifferent types of impactions with postoperativeinflammatory tissue reaction. Materials & Methods: Consecutive patients with only mandibular third molar impactions were included in our study. They were classified by winter’s classification. The disimpactions were performed under local anaesthesia. Time for surgery was noted for each surgical procedure. Postoperative inflammatory complication in terms of pain, swelling and trismus were noted. Results: 150 male patients in the age groupof 18-40 years were studied. Inflammatory tissue reactions were increasing with more operative time. Distoangular and Horizontal impactions were associated with more pain on first 3 days of surgery along with more swelling and trismus. Vertically impacted teeth were associated with least complications. Conclusion: Post operative morbidity was increasing along with moreoperating time and increase in the depth of mandibular third molar impaction. How to cite the article: Mansuri S, Mujeeb A, Hussain SA, Hussain MA. Mandibular third molar impactions in male adults: Relationship of Operative time and Types of impaction on inflammatory complications. J Int Oral Health 2014;6(2):9-15. PMID:24876696

Mansuri, Samir; Mujeeb, Abdul; Hussain, Seema Abid; Hussain, Mohammed Abid Zahir

2014-01-01

292

Prospective double-blind clinical trial evaluating the effectiveness of Bromelain in the third molar extraction postoperative period  

PubMed Central

Objectives: To evaluate the anti-inflammatory and analgesic effect of Bromelain (pineapple extract) administered orally in the postoperative after extraction of impacted lower molars. Study Design: This is a prospective, placebo-controlled, unicentric, double-blind study; the sample size was 34 patients. The pre and postoperative outcomes, evaluated on the third (D3) and eighth day (D8), included inflamtion, pain and oral aperture, as well as the need for analgesics. One group received bromelain 150mg per day for three days and 100mg on days 4 to 7. The other group received placebo in the same dosage. All outcomes werrecorded quantitatively and analyzed with the Mann-Whitney U test for independent samples. Results: Although there were no statistically significant differences between the treatment groups, a trend towards less inflammation and improved oral aperture was observed in the group that received bromelain, compared to the group that received placebo. This trend can be attributed completely to random reasons, since there is no statistical difference in the results. Conclusions: Further studies are necessary to analyze different administration patterns and doses of bromelain for the use in the postoperative of impacted third molars. Key words:Tooth extraction, third molar, postoperative period, bromeline, clinical study. PMID:24316697

de la Barrera-Núñez, María C.; Yáñez-Vico, Rosa M.; Batista-Cruzado, Antonio; Heurtebise-Saavedra, Jean M.; Castillo-de Oyagüe, Raquel

2014-01-01

293

Sulfur infiltrated activated carbon cathodes for lithium sulfur cells: The combined effects of pore size distribution and electrolyte molarity  

NASA Astrophysics Data System (ADS)

In this paper, we adopted three different commercial activated carbon samples (ACs) having different particle size, specific surface area and pore size to make sulfur-carbon (S-AC) nanocomposites for rechargeable lithium sulfur batteries. The effect of the physical parameters of ACs and the combined effect of electrolyte molarity were investigated. The performance of the cells at two different temperatures of 25 and 70 °C were compared. For room temperature operation of the cells, the capacities of S infiltrated into microporous AC having smaller pore size and stronger interactions with sulfur and sulfides were lower than those of the S infiltrated into micro- and mesoporous ACs containing larger pores. In contrast, the microporous AC demonstrated higher capacity at the elevated temperature due to the improved ion transport rate. The effect of electrolyte molarity on the performance of Li/S cells was found to depend on the AC pore size and particle size distributions. Increasing electrolyte molarity from 1 to 3 M demonstrated improved cell performance and reduced polysulfide dissolution in all the studied S-AC samples. However, further increasing electrolyte salt concentration resulted in a high polarization and reduced cell performance in S-ACs having large particle size or smaller pores.

Lee, Jung Tae; Zhao, Youyang; Kim, Hyea; Cho, Won Il; Yushin, Gleb

2014-02-01

294

Self-assembly of myristic acid in the presence of choline hydroxide: Effect of molar ratio and temperature.  

PubMed

Salt-free catanionic systems based on fatty acids exhibit a broad polymorphism by simply tuning the molar ratio between the two components. For fatty acid combined with organic amino counter-ions, very few data are available on the phase behavior obtained as a function of the molar ratio between the counter-ion and the fatty acid. We investigated the choline hydroxide/myristic acid system by varying the molar ratio, R=ncholine hydroxide/nmyristic acid, and the temperature. Myristic acid ionization state was determined by coupling pH, conductivity and infra-red spectroscopy measurements. Self-assemblies were characterized by small angle neutron scattering and microscopy experiments. Self-assembly thermal behavior was investigated by differential scanning calorimetry, wide angle X-ray scattering and nuclear magnetic resonance. For R<1, ionized and protonated myristic acid molecules coexisted leading to the formation of facetted self-assemblies and lamellar phases. The melting process between the gel and the fluid state of these bilayers induced a structural change from facetted or lamellar objects to spherical vesicles. For R>1, myristic acid molecules were ionized and formed spherical micelles. Our study highlights that both R and temperature are two key parameters to finely control the self-assembly structure formed by myristic acid in the presence of choline hydroxide. PMID:25626134

Arnould, Audrey; Perez, Adrian A; Gaillard, Cédric; Douliez, Jean-Paul; Cousin, Fabrice; Santiago, Liliana G; Zemb, Thomas; Anton, Marc; Fameau, Anne-Laure

2015-05-01

295

Nano-Molar Deltamethrin Sensor Based on Electrical Impedance of PAH/PAZO Layer-by-Layer Sensing Films  

PubMed Central

This work reports a novel deltamethrin (DM) sensor able to detect nano-molar concentrations in ethanol solutions. The sensing layer consists of a thin film, obtained via a layer-by-layer technique, from alternate adsorption of poly(allylamine chloride) (PAH) and poly[1-[4-(3-carboxy-4-hydroxyphenylazo)-benzenesulfonamide)-1,2-ethanediyl]sodium salt] (PAZO) onto a solid support with interdigitaded gold electrodes. The sensor response, obtained from impedance spectroscopy measurements, was revealed to be linear with respect to the real part of impedance, taken at 100 Hz, when plotted as a function of the logarithm of deltamethrin molar concentrations in the micro- to nano-molar range. Sensor sensitivity was of 41.1 ± 0.7 k? per decade of concentration for an immersion time above 2 min and the reproducibility is approximately 2% in a binary solution of ethanol and deltamethrin. The main insight of this work concerns to DM detection limits as the sensor revealed to be able to detect concentrations below 0.1 nM, a value which is significantly lower than any reported in the literature and close what is appropriate for in situ environmental contaminant detection. PMID:23966185

Abegão, Luís Miguel Gomes; Ribeiro, Jorge Humberto Fernandes; Ribeiro, Paulo António; Raposo, Maria

2013-01-01

296

Low-temperature heat capacities and standard molar enthalpy of formation of pyridine-2,6-dicarboxylic acid  

NASA Astrophysics Data System (ADS)

This paper reports that the low-temperature heat capacities of pyridine-2,6-dicarboxylic acid were measured by a precision automatic calorimeter over a temperature range from 78 K to 380 K. A polynomial equation of heat capacities as a function of temperature was fitted by the least-squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K. The constant-volume energy of combustion of the compound was determined by means of a precision rotating-bomb combustion calorimeter. The standard molar enthalpy of combustion of the compound was derived from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound was calculated from a combination of the datum of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.

Yang, Wei-Wei; Di, You-Ying; Kong, Yu-Xia; Tan, Zhi-Cheng

2010-06-01

297

Pre-operative assessment of relationship between inferior dental nerve canal and mandibular impacted third molar in Saudi population  

PubMed Central

Objective To study the correlation between the position of the inferior dental (ID) nerve canal and the angulation of impacted mandibular third molars using dental cone beam computed tomography (CBCT). Materials and methods The study considered 100 impactions in 85 patients (60 males, 25 females), for whom an initial panoramic radiographic assessment had revealed that the ID canal and the lower 3rd molar were in close proximity. A CBCT scan of each patient was carried out to assess how the ID nerve canal position influenced the class and position of impaction, angulation of impaction, and bone contact. Results Class I position B impactions were found in the majority of cases, where the position of the ID canal was approximate to the lingual plate and inferior to the 3rd molar (85.7%). The results were statistically significant (p = 0.001). 96% of the ID canals showed bone contact. Of these, 77.1% of ID canals exhibited lingual bone contact, inferior to impaction. The results were statistically significant (p = 0.001). Horizontally angulated impactions were most common in the mandible, and significantly associated with lingual and inferior positioning of the ID canal (76.2%). Conclusions Our sample population most commonly exhibited horizontally angulated class I position B impactions of the mandible. The position of the ID canal significantly influenced the type of impaction and bone contact. PMID:25057230

Shujaat, S.; Abouelkheir, H.M.; Al-Khalifa, K.S.; Al-Jandan, B.; Marei, H.F.

2014-01-01

298

Evaluation of the root and canal morphology of mandibular permanent molars in a south-eastern Turkish population using cone-beam computed tomography  

PubMed Central

Objective: The aim of this retrospective study was to determine the root and canal morphology of the mandibular first and second permanent molars in a Turkish population using cone-beam computed tomography (CBCT). Materials and Methods: CBCT images of mandibular first (n = 966) and second molar (n = 1165) teeth from 850 Turkish patients were evaluated. The root canal configurations were classified according to the method of Vertucci. The data were analyzed by Pearson's Chi-square test. Results: The majority of mandibular molars were two rooted with three canals; however, three roots were identified in 0.05% of the first molars and 0.01% of the second molars, and 100% of the additional root canals were of type I configuration. Mesial roots had more complex canal systems with more than one canal, whereas most distal roots had a type I configuration. Conclusions: Within the limitations of this study, it can be concluded that CBCT scanning provides supplemental information about the root canal configurations of mandibular molars in a Turkish population. This study may help clinicians in the root canal treatment of mandibular molars. PMID:24966763

Nur, Bilge Gulsum; Ok, Evren; Altunsoy, Mustafa; Aglarci, Osman Sami; Colak, Mehmet; Gungor, Enes

2014-01-01

299

Volumetric Measurement of Root Resorption following Molar Mini-Screw Implant Intrusion Using Cone Beam Computed Tomography  

PubMed Central

Objective Molar intrusion by mini-screw implantation can cause different degrees of root resorption. However, most methods (2-D and 3-D) used for evaluating root resorption have focused on the root length without considering 3-D resorption. The purpose of this study was to volumetrically evaluate root resorption using cone beam computed tomography(CBCT) after mini-screw implant intrusion. Materials and Methods 1. The volumes of 32 teeth were measured using CBCT and laser scanning to verify the accuracy of CBCT. 2. Twelve overerupted molars from adult patients were investigated in this study. After mini-screw implants were inserted into the buccal and palatal alveolar bones, 150 g of force was applied to the mini-screw implants on each side to intrude the molars. CBCT images of all patients were taken immediately prior to intrusion and after intrusion. The volumes of the roots were calculated using the Mimics software program. The differences between the pre-intrusion and post-intrusion root volumes were statistically evaluated with a paired-samples t-test. In addition, the losses of the roots were statistically compared with each other using one-way analysis of variance at the P<0.05 level. Results No statistically significant volume differences were observed between the physical (laser scanning) and CBCT measurements (P>0.05). The overerupted molars were significantly intruded (P<0.05), and the average intrusion was 3.30±1.60 mm. The differences between the pre-intrusion and post-intrusion root volumes were statistically significant for all of the roots investigated (P<0.05). The roots were sorted by volume loss in descending order as follows: mesiobuccal, palatal, and distobuccal. Statistical significance was achieved among the three roots. The average total resorption for each tooth was 58.39±1.54 mm3. Conclusion Volume measurement using CBCT was able to effectively evaluate root resorption caused by mini-screw intrusion. The highest volume loss was observed in the mesiobuccal root among the three roots of the investigated first molar teeth. PMID:23585866

Li, Wen; Chen, Fei; Zhang, Feng; Ding, Wanghui; Ye, Qingsong; Shi, Jiejun; Fu, Baiping

2013-01-01

300

Ibuprofen is superior to paracetamol for pain relief following third molar removal.  

PubMed

Data sourcesThe Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase and the metaRegister of Controlled Trials were searched with no language restrictions.Study selectionRandomised controlled double-blinded clinical trials using the third molar model were included.Data extraction and synthesisTwo review authors independently and in duplicate extracted data. The proportion of patients with at least 50% pain relief (based on total pain relief (TOTPAR) and summed pain intensity difference (SPID) data) was calculated for all three drugs at both two and six hours post-dosing and meta-analysed for comparison.ResultsSeven studies involving 2241 patients were included. Two studies were considered to be at low risk of bias, three at high risk and two unclear risk of bias. Ibuprofen was found to be a superior analgesic to paracetamol at several doses, with high quality evidence suggesting that ibuprofen 400 mg is superior to 1000 mg paracetamol based on pain relief (estimated from TOTPAR data) and the use of rescue medication meta-analyses. Risk ratio (RR) for at least 50% pain relief (based on TOTPAR) at six hours was 1.47 (95% confidence interval (CI) 1.28 to 1.69; five trials) favouring 400 mg ibuprofen over 1000 mg paracetamol, RR for not using rescue medication (also favouring ibuprofen) was 1.50 (95% CI 1.25 to 1.79; four trials). For combined drug RR for at least 50% of the maximum pain relief over six hours of 1.77 (95% CI 1.32 to 2.39) (paracetamol 1000 mg and ibuprofen 400 mg) (one trial; moderate quality evidence). RR not using rescue medication 1.60 (95% CI 1.36 to 1.88) (two trials; moderate quality evidence). Adverse events were comparable between the treatment groups, but no formal analysis could be undertaken.ConclusionsThere is high quality evidence that ibuprofen is superior to paracetamol at doses of 200 mg to 512 mg and 600 mg to 1000 mg respectively based on pain relief and use of rescue medication data collected at six hours postoperatively. The majority of this evidence (five out of six trials) compared ibuprofen 400 mg with paracetamol 1000 mg, these are the most frequently prescribed doses in clinical practice. The novel combination drug is showing encouraging results based on the outcomes from two trials when compared to the single drugs. PMID:25522940

Ferraiolo, Debra M; Veitz-Keenan, Analia

2014-12-01

301

Caries management strategies for primary molars: 1-yr randomized control trial results.  

PubMed

Minimal invasive approaches to managing caries, such as partial caries removal techniques, are showing increasing evidence of improved outcomes over the conventional complete caries removal. There is also increasing interest in techniques where no caries is removed. We present the 1-yr results of clinical efficacy for 3 caries management options for occlusoproximal cavitated lesions in primary molars: conventional restorations (CR; complete caries removal and compomer restoration), Hall technique (HT; no caries removal, sealing in with stainless steel crowns), and nonrestorative caries treatment (NRCT; no caries removal, opening up the cavity, teaching brushing and fluoride application). In sum, 169 children (3-8 yr old; mean, 5.56 ± 1.45 yr) were enrolled in this secondary care-based, 3-arm, parallel-group, randomized clinical trial. Treatments were carried out by specialist pediatric dentists or postgraduate trainees. One lesion per child received CR, HT, or NRCT. Outcome measures were clinical failure rates, grouped as minor failure (restoration loss/need for replacement, reversible pulpitis, caries progression, etc.) and major failure (irreversible pulpitis, abscess, etc.). There were 148 children (87.6%) with a minimum follow-up of 11 mo (mean, 12.23 ± 0.98 mo). Twenty teeth were recorded as having at least 1 minor failure: NRCT, n = 8 (5%); CR, n = 11 (7%); HT, n = 1 (1%) (p = .002, 95% CI = 0.001 to 0.003). Only the comparison between NRCT and CR showed no significant difference (p = .79, 95% CI = 0.78 to 0.80). Nine (6%) experienced at least 1 major failure: NRCT, n = 4 (2%); CR, n = 5 (3%); HT, n = 0 (0%) (p = .002, 95% CI = 0.001 to 0.003). Individual comparison of NRCT and CR showed no statistically significant difference in major failures (p = .75, 95% CI = 0.73 to 0.76). Success and failure rates were not significantly affected by pediatric dentists' level of experience (p = .13, 95% CI = 0.12 to 0.14). The HT was significantly more successful clinically than NRCT and CR after 1 yr, while pairwise analyses showed comparable results for treatment success between NRCT and CR (ClinicalTrials.gov NCT01797458). PMID:25216660

Santamaria, R M; Innes, N P T; Machiulskiene, V; Evans, D J P; Splieth, C H

2014-11-01

302

Molecular Polarizability of Organic Compounds and Their Complexes: XLVIII. Molar Volumes of Benzene Derivatives in Solutions at Infinite Dilution, Their Additivity, and Correlation with the Dipole Moments and Kerr Constants  

Microsoft Academic Search

Extrapolation formulas were derived for determination of the molar volume of a solute at infinite dilution. This quantity\\u000a is stable to solvent replacement and additive with respect to increments of substituents in polysubstituted benzenes. The\\u000a molar polarization and molar Kerr constant of a solute can be expressed through the molar volumes of the solute at infinite\\u000a dilution and of the

S. B. Bulgarevich; T. V. Burdastykh; L. G. Tishchenko; I. V. Kosheleva

2005-01-01

303

Determination of Frequency of the Second Mesiobuccal Canal in the Permanent Maxillary First Molar Teeth with Magnification Loupes (× 3.5)  

PubMed Central

INTRODUCTION: The mesiobuccal root of the maxillary first molar has generated more research and clinical investigation than any root. An inability to detect and treat a second mesiobuccal (MB2) canal is a reason for endodontic failure in maxillary first molars. Modifications in the endodontic access and detection techniques, along with advancements in illumination and magnification technology, have aided in the location and treatment with the second mesiobuccal canal of maxillary first molars. OBJECTIVE: To determine the frequency of the second mesiobuccal canal in the permanent maxillary first molars with magnification loupes (× 3.5). MATERIALS AND METHODS: A total of 53 teeth were assessed using a moderate magnification for second mesiobuccal canal in mesiobuccal root of first permanent maxillary molars in vivo. Detection of this canal in maxillary first molars was done through a clinical access cavity preparation under magnification loupes (× 3.5). Data was analyzed using SPSS 15.0. Frequency distribution of variables was determined and the level of significance was kept at 0.05. RESULTS: We were able to detect second mesiobuccal canal in 27 out of 53 (50.9%) of the permanent maxillary first molars that were studied. It was found that the males tend to have a higher proportion of second mesiobuccal canals (up to 31%) as compared to the females in whom the second mesiobuccal canals could be identified only 19% of the time. Whilst, there was no association found between age, gender and chamber obliteration with the presence of second mesiobuccal canal. CONCLUSIONS: In conclusion, within its limitations, this study suggested that the use of magnification loupes enhanced both the detection (50.9%) and negotiation (86.8%) of the second mesiobuccal canals in the permanent maxillary first molars beyond what could be achieved with naked eye. PMID:25324702

Hasan, Muhammad; Raza Khan, Farhan

2014-01-01

304

Comparison of Maxillary Molar Distalization with an Implant-Supported Distal Jet and a Traditional Tooth-Supported Distal Jet Appliance  

PubMed Central

Aim. To investigate and compare the efficiency of two appliances for molar distalization: the bone-anchored distal screw (DS) and the traditional tooth-supported distal jet (DJ) for molar distalization and anchorage loss. Methods. Tests (18 subjects) were treated with a DS and controls (18 subjects) were treated with a DJ. Lateral cephalograms were obtained before and at the end of molar distalization and were analysed. Shapiro Wilk test, unpaired t-test, and Wilcoxon rank-sum test were applied according to values distribution. The ? level was fixed at 0.05. Results. Maxillary first molars were successfully distalized into a Class I relationship in all patients. The mean molar distalization and treatment time were similar in both groups. The DS group exhibited a spontaneous distalization (2.1 ± 0.9?mm) of the first premolar with control of anchorage loss, distal tipping, extrusion, and skeletal changes. Conclusions. The DS is an adequate compliance-free distalizing appliance that can be used safely for the correction of Class II malocclusions. In comparison to the traditional DJ, the DS enables not only a good rate of molar distalization, but also a spontaneous distalization of the first premolars. PMID:25018770

Cozzani, Mauro; Pasini, Marco; Zallio, Francesco; Ritucci, Robert; Mutinelli, Sabrina; Mazzotta, Laura; Giuca, Maria Rita; Piras, Vincenzo

2014-01-01

305

Frequency and distribution of early tooth loss and endodontic treatment needs of permanent first molars in a Turkish pediatric population  

PubMed Central

Objectives: The objective of this study is to evaluate the frequency and distribution of early tooth loss and endodontic treatment needs of permanent first molars in a Turkish pediatric population. Materials and Methods: A total of 7,895 panoramic radiographs taken for routine dental examination at the Department of Oral Maxillofacial Radiology between 2008 and 2012 years were investigated. Two independent specialists evaluated early tooth loss and endodontic treatment needs of permanent first molars using panoramic radiography and patient anamnesis forms. The teeth were classified according to the following data: (a) Missing teeth, (b) teeth requiring extraction, (c) endodontically treated teeth (ETT), (d) teeth requiring endodontic therapy. The data also classified according to four factors: Age group (6-12 and 13-16), gender (boy and girl), jaw (mandible and maxilla) and side (right and left). A Chi-square test was used for statistical analyses. Results: A total of 19,488 and 12,092 teeth were evaluated in the child group and adolescent group respectively. All data were higher in adolescents than children (P < 0.001). For gender factor, only ETT was higher in girls than it was in boys (P < 0.001). For the jaw factor, all data were higher (P < 0.001) in mandible than in the maxilla. For the side factor, no statistical difference existed between right and left. Conclusions: Early tooth loss and endodontic treatment needs of permanent first molars showed variability according to age groups and jaws. When the results were compared according to the side and gender factors, no statistical difference was found (P > 0.05) except with the data of ETT in gender groups. PMID:24966738

Demirbuga, Sezer; Tuncay, Oznur; Cantekin, Kenan; Cayabatmaz, Muhammed; Dincer, Asiye Nur; Kilinc, Halil ?brahim; Sekerci, Ahmet Ercan

2013-01-01

306

Position of impacted mandibular third molar in different skeletal facial types: First radiographic evaluation in a group of Iranian patients  

PubMed Central

Purpose This study was performed to evaluate the position of impacted mandibular third molars in different skeletal facial types among a group of Iranian patients. Materials and Methods A total of 400 mandibular third molars in 200 subjects with different types of facial growth were radiographically investigated for their positions according to their types of facial growth on the basis of the ? angle. The subjects were divided into three groups (class I, II, and III) according to ANB angle, representing the anteroposterior relationship of the maxilla to the mandible. Meanwhile, the subjects were also divided into three groups (long, normal, and short face) according to the angle between the stella-nasion and mandibular plane (SNGoGn angle). ANOVA was used for statistical analysis. Results The mean ? angle showed no significant difference among class I, II, and III malocclusions (df=2, F=0.669, p=0.513). The same results were also found in short, normal, and long faces (df=1.842, F=2, p=0.160). The mesioangular position was the most frequent one in almost all of the facial growth patterns. Distoangular and horizontal positions of impaction were not found in the subjects with class III and normal faces. In the long facial growth pattern, the frequency of vertical and distoangular positions were not different. Conclusion In almost all of the skeletal facial types, the mesioangular impaction of the mandibular third molar was the most prevalent position, followed by the horizontal position. In addition, ? angle showed no significant difference in different types of facial growth. PMID:24701460

Shokri, Abbas; Mahmoudzadeh, Majid; Baharvand, Maryam; Faradmal, Javad; Khajeh, Samira; Yousefi, Faezeh; Noruzi-Gangachin, Maruf

2014-01-01

307

Analysis of the dental morphology of Plio-pleistocene hominids. I. Mandibular molars: crown area measurements and morphological traits.  

PubMed Central

This study has used accurate measurements of crown area and precise assessments of the morphological traits of mandibular molars in an attempt to define the metrical and morphological characteristics of early hominid taxa. A total of 196 Plio-Pleistocene hominid molars were either allocated to one of six informal taxonomic groups or considered as individual cases. Accurate measurements of crown base area made from occlusal photographs have enabled us to estimate the effects of interproximal wear on crown areas. The average correction factor over the three molar types is around 2-4% with a maximum of 6%. The patterns of distribution of extra cusps show interesting differences between taxa. None of the M-1S in the two groups of 'gracile' hominids from East and South Africa bears a C6, but it is common in the two 'robust' taxa. The distribution of a C7 is the reverse of this, it being rare in the robust' taxa, and more common in the 'gracile' groups. There is thus no simple relationship between cusp number and tooth size. Our observations on the protostylid suggest that though it is more common in the 'robust' australopithecines than the 'graciles', when it does occur it is more strongly expressed in the 'gracile' group. The combination of simple metrical data, and the assessment of morphological traits, can help in the classification of enigmatic or incomplete specimens. Some isolated teeth from the collection at Koobi Fora can confidently be assigned to Australopithecus boisei, and useful guides have been provided for taxonomic assessment of the skull KNM-ER 1805, and the mandibles KNM-ER 1506 and 1820. PMID:6403498

Wood, B A; Abbott, S A

1983-01-01

308

Analysis of stress in the periodontium of the maxillary first molar with a three-dimensional finite element model.  

PubMed

The aim of this study was to simulate the stress response in the periodontium of the maxillary first molar to different moment to force ratios, and to determine the moment to force ratio for translational movement of the tooth by means of the finite element method. The three-dimensional finite element model of the maxillary first molar consisted of 3097 nodes and 2521 isoparametric eight-node solid elements. The model was designed to dissect the periodontal ligament, root, and alveolar bone separately. The results demonstrate the sensitivity of the periodontium to load changes. The stress pattern in the periodontal ligament for a distalizing force without counterbalancing moments showed high concentration at the cervical level of the distobuccal root due to tipping and rotation of the tooth. After various counterrotation as well as countertipping moments were applied, an even distribution of low compression on the distal side of the periodontal ligament was obtained at a countertipping moment to force ratio of 9:1 and a counterrotation moment to force ratio of 5:1. This lower and uniform stress in the periodontal ligament implies that a translational tooth movement may be achieved. Furthermore, high stress concentration was observed on the root surface at the furcation level in contrast with anterior teeth reported to display high concentration at the apex. This result may suggest that the root morphology of the maxillary first molar makes it less susceptible to apical root resorption relative to anterior teeth during tooth movement. The stress patterns in the periodontal ligament corresponded with the load types; those on the root appeared to be highly affected by bending and the high stiffness of the root. PMID:10066974

Jeon, P D; Turley, P K; Moon, H B; Ting, K

1999-03-01

309

Endodontic Management of Maxillary Second Molars Fused with Paramolar Tubercles Diagnosed by Cone Beam Computed Tomography - Two Case Reports  

PubMed Central

The main objective of nonsurgical endodontic treatment is to eliminate micro-organisms from the root canal system. Adequate knowledge of the root canal morphology and its complexities is essential to render successful endodontic treatment. Variations in tooth form and morphology may be found in the form of anomalous cusps in the crown region or additional roots. In permanent molars, changes in the crown morphology may occur either in the form of an additional tooth (paramolar) or supernumerary cusp termed as “paramolar tubercle”. PMID:25628705

Jain, Preetham; Ananthnarayan, Krishnamurthi; Ballal, Suma; Natanasabapathy, Velmurugan

2014-01-01

310

Microleakage of nano-particle-filled resin-modified glass ionomer using atraumatic restorative technique in primary molars.  

PubMed

This study compared the marginal leakage of nano-particle-filled resin-modified glass ionomer (RMGIC) restorations made using atraumatic restorative technique (ART) and conventional technique. Twenty primary molars with carious dentin on the buccal surfaces were restored with RMGIC using ART. The teeth were thermally cycled, sectioned and stained with methylene blue. Micro-leakage was compared to a second set of teeth restored conventionally. No significant difference (p > 0.05) in leakage was noted between the conventional and ART groups. The authors concluded that ART with RMGIC provides margins that show comparable leakage to conventionally restored primary teeth. PMID:20863039

Wadenya, Rose; Smith, Jennifer; Mante, Francis

2010-01-01

311

Human dental age estimation using third molar developmental stages: Accuracy of age predictions not using country specific information.  

PubMed

Unquestionable forensic age investigations are based on statistical models constructed on a sample containing subjects of identical origin as the examined individual. In cases where corresponding models are unavailable, the established report has to describe the possible effects of this unrelated information on the predicted age outcome. The aim of this study is to collect country specific databases of third molar development and to verify how the related dental age estimations are influenced if we were to use dental developmental information only from Belgium or from all collected countries together. Data containing third molar developmental stages scored following Gleiser and Hunt (modified by Köhler) were collected from 9 country specific populations (Belgium, China, Japan, Korea, Poland, Thailand, Turkey, Saudi-Arabia and South-India). Age predictions were obtained from a training dataset and validated on a test dataset. Bayes rule using the repeated third molar scores is applied to get age predictions and prediction intervals. Three age predictions were compared for males and females separately. For the first prediction, the training dataset contains only Belgian subjects. For the second prediction, the training dataset for each country consists only of subjects of the country itself. For the final prediction, subjects from all countries are pooled into one common training dataset. Besides the (absolute) difference between the chronological age and the predicted age, specific interest lies in the juvenile-adult distinction. In the age range from 16 to 22 years 6982 subjects (3189 male and 3793 female) were analyzed. Using information on third molar development from Belgium compared to information from the country specific databases hardly increased the mean absolute differences (MAD) and mean squared errors (MSE): the MAD and MSE increased on average with 0.5 and 2.5 months with maximal increases of, respectively 1.6 and 7.3 months. Using information from all countries pooled compared to country specific information provided even on average negligible increases (0.05 and 0.2 months for MAD and MSE, respectively). For the juvenile-adult discrimination, using information from all countries instead of country specific information yielded comparable performances. Using Belgium instead of country specific information increased the percentage of correctly identified juveniles, but decreased the percentage of correctly identified adults. The adult-juvenile discrimination based on information used from Belgium provides judicially the best applied reference. PMID:20483555

Thevissen, P W; Alqerban, A; Asaumi, J; Kahveci, F; Kaur, J; Kim, Y K; Pittayapat, P; Van Vlierberghe, M; Zhang, Y; Fieuws, S; Willems, G

2010-09-10

312

Cryotherapy and Topical Minocycline as Adjunctive Measures to Control Pain After Third Molar Surgery: An Exploratory Study  

PubMed Central

Purpose To assess the impact of cryotherapy or topical minocycline on patients’ perceptions of recovery from pain after third molar surgery in an exploratory comparative-effectiveness study. Patients and Methods Subjects aged at least 14 years who were having all 4 third molars removed were enrolled in 3 separate institutional review board–approved studies. Study groups included subjects treated with a passively applied cold wrap for 24 hours postoperatively, subjects treated with topical minocycline during surgery, and subjects enrolled in a nonconcurrent comparison group who had received neither topical minocycline nor directed cryotherapy. Third molar surgery was performed in all cases by trained surgeons using the same protocol. An exact Kruskal-Wallis test was used to compare the distributions of the worst and average pain scores and a Fisher exact test to compare verbal responses from Gracely pain scales among the 3 groups for postsurgical days (PSDs) 1 to 3. Results This study comprised 51 cryotherapy subjects (2005–2009), 63 minocycline subjects (2003–2004), and 92 comparison-group subjects (2002–2006) who were treated at academic centers and in community practices across the United States (N = 206). Demographic descriptors were similar among all groups. For PSDs 1 through 3 (unadjusted), the highest scores for worst pain (6–7 [out of 7] on Likert-type scale) were reported less frequently in each of the study groups than in subjects in the comparison group, although the numbers of subjects reporting the highest scores were few. The distribution of pain outcomes was significantly different among the 3 groups for worst pain and affective words on PSD 1 (P = .04 for both). However, the small number of subjects who reported the highest pain scores precluded adequate multivariate statistical analyses for all outcomes on PSD 1 to 3. Conclusions Data from this exploratory study suggest that adjunctive therapy to decrease postoperative pain—cryotherapy or topical minocycline—might be effective at moderating the patient’s highest pain levels after third molar surgery. The topic should be studied further in a multicenter, prospective, randomized trial. PMID:21802812

Gelesko, Savannah; Long, Leann; Faulk, Jan; Phillips, Ceib; Dicus, Carolyn; White, Raymond P.

2013-01-01

313

Localization and significance of urokinase plasminogen activator and its receptor in placental tissue from intrauterine, ectopic and molar pregnancies.  

PubMed

Urokinase plasminogen activator receptor (uPAR) is a membrane-anchored protein with urokinase plasminogen activator (uPA) as the ligand. This complex induces proteolysis and remodelling of maternal decidua during placental implantation. The presence of uPAR on trophoblasts is supposed to promote adhesion, migration and invasion. In cancer tissue, high levels of uPAR are correlated with a poor prognosis. This immunohistochemical study shows the localization of uPA and uPAR in a prospective design with stereological sampling of fetal and maternal tissue from normal, ectopic and hydatidiform molar (HM) pregnancies. Cytokeratin and Ki67 were used as markers for trophoblasts and proliferating cells. Membrane-bound uPAR was observed on villous non-proliferating intermediate trophoblasts (IT) within cell columns in intrauterine and ectopic pregnancies. The corresponding proliferating IT with cytological atypia sprouting from the chorionic villi in HM was uPAR-negative. uPA but not uPAR was observed in anchoring distal IT at the attachment-point to the basal plate. In the placental bed, extravillous interstitial trophoblasts were uPA-positive but uPAR-negative. The trophoblast giant cells were both uPA- and uPAR-negative. In relation to the maternal vessels, a focal distribution for uPA and uPAR was present in the endovascular and perivascular trophoblasts. The intraluminal trophoblasts overlying endothelial cells were uPAR-positive only. In maternal tissue from intrauterine and molar pregnancies, uPAR was seen in the decidual cells in a zone facing the anchoring villi and the fibrinoid lesions with embedded trophoblasts. In contrast, the stromal cells of the fallopian tube without a decidual reaction facing the implanted gestation were uPAR-negative. Non-invaded decidual, myometrial and muscular tissue of the pregnant uterus and fallopian tube was extensively positive for uPA whereas 'pseudodecidual' cells from the intrauterine evacuate in patients with an ectopic pregnancy only showed a focal and scanty reaction for uPA. When trophoblast invasion of the decidua was present, the decidual cells were uPA-negative. A semi-quantitative assessment of the receptor was estimated in villous IT within cell columns in normal and molar pregnancies but, in conclusion, quantitative evaluation of uPAR cannot be used to predict development of post-molar persistent trophoblastic disease (PTD). PMID:10527826

Floridon, C; Nielsen, O; Holund, B; Sunde, L; Westergaard, J G; Thomsen, S G; Teisner, B

1999-11-01

314

Endodontic management of maxillary second molars fused with paramolar tubercles diagnosed by cone beam computed tomography - two case reports.  

PubMed

The main objective of nonsurgical endodontic treatment is to eliminate micro-organisms from the root canal system. Adequate knowledge of the root canal morphology and its complexities is essential to render successful endodontic treatment. Variations in tooth form and morphology may be found in the form of anomalous cusps in the crown region or additional roots. In permanent molars, changes in the crown morphology may occur either in the form of an additional tooth (paramolar) or supernumerary cusp termed as "paramolar tubercle". PMID:25628705

Jain, Preetham; Ananthnarayan, Krishnamurthi; Ballal, Suma; Natanasabapathy, Velmurugan

2014-11-01

315

Collagen proteins in electrorefining: Rate constants for glue hydrolysis and effects of molar mass on glue activity  

NASA Astrophysics Data System (ADS)

Animal glue (collagen proteins) degradation was studied in water and in a simulated copper electrolyte (150 g/L H2SO4, 46 g/L Cu2+ as CuSO4) by size-exclusion chromatography. The rate of degradation was relatively slow in pure aqueous solutions, and depending on the temperature and glue concentration, some association to larger molar mass species was observed. For simulated electrolyte in a temperature range of 42 °C to 70 °C and a glue concentration range of 100 to 3000 mg/L, the degradation rate constant was described with the following relation: k' = 1.5· 107exp (-9951 /T), min-1 The degradation rate was zero order with respect to initial concentration of the protein and first order with respect to acid concentration. The results show that glue degradation under normal tankhouse operation should be rapid, with degradation to number-average molar mass (M n ) < 10,000 units occurring in about 40 to 80 minutes depending on the mass transfer rate (or mixing) of the electrolyte solution. Samples of glue from three different sources showed almost no difference in degradation rates. Results calculated from the rate equation for glue degradation have been correlated with cathode polarization data from the literature, and the results suggest that critical glue M n below which the glue loses most of its activity is 3700.

Saban, M. D.; Scott, J. D.; Cassidy, R. M.

1992-03-01

316

Comparison of two incision designs for surgical removal of impacted mandibular third molar: A randomized comparative clinical study  

PubMed Central

Objective: The objective of this study is to investigate the influence of flap design on visibility and accessibility during removal of impacted third molar and hematoma formation, wound gaping and healing of flap post-operatively. Study Design: The randomized prospective comparative study included 30 patients with impacted mandibular third molars. Two flap designs namely envelope flap (Koener's incision) and ‘triangular flap’ (Ward's incision) were used. After 7 days, sutures were removed and status of wound, periodontal health, and progress of healing was assessed. Patients were followed through 15 days to judge the incidence of post-operative complications in both groups. Results: No statistical differences were noted between the groups in terms of visibility, accessibility, excessive bleeding during surgery, healing of flap, sensitivity of adjacent teeth, and dry socket. A statistically significant difference was observed in post-operative hematoma, wound gaping, and distal pocket in adjacent tooth, which was significant in Ward's triangular incision group in comparison to Koeiner's envelope incision group. Conclusion: The selection of the flap design is dependent on needs of the case and preference of the operating surgeon and does not seem to have a significant influence on the health of tissues. In order to avoid wide area of exposure of bone, the operating surgeon should clinically and radiographically assess the designing of incision and mucoperiosteal flap, the clinical relevance is still debatable. PMID:24963241

Desai, Adarsh; Patel, Rushit; Desai, Kiran; Vachhani, Nirav Bharatbhai; Shah, Kruti A; Sureja, Raj

2014-01-01

317

Variations in the methanesulfonate to sulfate molar ratio in submicrometer marine aerosol particles over the south Pacific Ocean  

NASA Astrophysics Data System (ADS)

Seawater concentrations of dimethylsulfide (DMS) and atmospheric concentrations of DMS, sulfur dioxide, methanesulfonate (MSA), and non-sea-salt (nss) sulfate were measured over the eastern Pacific Ocean between 105 deg and 110 deg W from 20 deg N to 60 deg S during February and March 1989. Although the samples collected in the Southern Hemisphere appear to be of marine origin, no significant correlation was found between the latitudinal distributions of DMS, SO2, MSA, and nss SO4(2-). However, an inverse correlation was found between atmospheric temperature and the MSA to nss SO4(2-) molar ratio in submicrometer aerosol particles with a decrease in temperature corresponding to an increase in the molar ratio. Although this trend is consistent with laboratory results indicating the favored production of MSA at lower temperatures, it is contrary to Southern Hemisphere baseline station data. This suggests either a decrease in the supply of DMS relative to nonmarine sources of nss SO4(2-) at the baseline stations in winter or additional mechanisms that affect the relative production of MSA and nss SO4(2-).

Bates, Timothy S.; Calhoun, Julie A.; Quinn, Patricia K.

1992-06-01

318

Variations in the methanesulfonate to sulfate molar ratio in submicrometer marine aerosol particles over the south Pacific Ocean  

NASA Technical Reports Server (NTRS)

Seawater concentrations of dimethylsulfide (DMS) and atmospheric concentrations of DMS, sulfur dioxide, methanesulfonate (MSA), and non-sea-salt (nss) sulfate were measured over the eastern Pacific Ocean between 105 deg and 110 deg W from 20 deg N to 60 deg S during February and March 1989. Although the samples collected in the Southern Hemisphere appear to be of marine origin, no significant correlation was found between the latitudinal distributions of DMS, SO2, MSA, and nss SO4(2-). However, an inverse correlation was found between atmospheric temperature and the MSA to nss SO4(2-) molar ratio in submicrometer aerosol particles with a decrease in temperature corresponding to an increase in the molar ratio. Although this trend is consistent with laboratory results indicating the favored production of MSA at lower temperatures, it is contrary to Southern Hemisphere baseline station data. This suggests either a decrease in the supply of DMS relative to nonmarine sources of nss SO4(2-) at the baseline stations in winter or additional mechanisms that affect the relative production of MSA and nss SO4(2-).

Bates, Timothy S.; Calhoun, Julie A.; Quinn, Patricia K.

1992-01-01

319

Enamel hypoplasia in molars of sheep and goats, and its relationship to the pattern of tooth crown growth  

PubMed Central

Enamel is the most highly mineralized and durable tissue of the mammalian body. As enamel does not undergo remodeling or repair, disturbances of enamel formation leave a permanent record in the tissue that can be used for life history reconstruction. This study reports light and scanning electron microscope findings on hypoplastic enamel defects, and on the chronology of crown growth in the molars of sheep and goats. A marked reduction of enamel extension rates in cervical compared with more cuspal crown portions of sheep and goat molars was recorded, with formation of the cervical 25% of the crown taking about the same time as that of the upper 75% of the crown. This explains the more frequent occurrence of enamel hypoplasia in cervical compared with upper and middle crown portions. Regarding the identification of hypoplastic enamel defects by external inspection, our results suggest a dependence on the type of defect and the associated presence of smaller or larger amounts of coronal cementum. Defects considered to reflect a slight to moderate impairment of secretory ameloblast function can normally be correctly diagnosed as they are not occluded by thick layers of cementum. In contrast, defects denoting a severe impairment of enamel matrix secretion can typically not be correctly identified because they are occluded by large amounts of cementum, so that neither depth nor extension of the defects can be assessed on external inspection. In these cases, microscopic analysis of tooth sections is required for a correct diagnosis of the hypoplastic enamel defects. PMID:22352403

Kierdorf, H; Witzel, C; Upex, B; Dobney, K; Kierdorf, U

2012-01-01

320

Selenium and mercury molar ratios in saltwater fish from New Jersey: Individual and species variability complicate use in human health fish consumption advisories?  

PubMed Central

Balancing risk versus benefits to humans and other organisms from consuming fish is a national concern in the USA, as well as in many other parts of the world. Protecting public health is both a federal and state responsibility, and states respond by issuing fish consumption advisories, particularly for mercury. Recently it has been emphasized that the protective role of selenium against mercury toxicity depends on their molar ratios, which should be evaluated as an indication of selenium’s protective capacity, and incorporated in risk assessments for fish consumption. However, there is no single “protective” ratio agreed upon. In this paper we examine the selenium:mercury (Se:Hg) molar ratios in a wide range of saltwater fish caught and eaten by recreational fishers along the New Jersey coast. We were particularly interested in interspecific and intraspecific variability, and whether the molar ratios were consistent within a species, allowing for its use in managing risk. The selenium–mercury molar ratio showed significant variation among and within fish species. The molar ratio decreased with the size of the fish species, decreased with the mercury levels, and within a fish species, the selenium:mercury ratio decreased with fish size. As an essential element, selenium undergoes some homeostatic regulation, but it is also highly toxic. Within species, mercury level tends to increase with size, accounting for the negative relationship between size and ratio. This variability may make it difficult to use the selenium:mercury molar ratio in risk assessment, risk management, and risk communication at this time, and more information is needed on how mercury and selenium actually interact and on the relationship between the molar ratios and health outcomes. PMID:22405995

Burger, Joanna; Gochfeld, Michael

2014-01-01

321

Determination of the partial molar volume of SiO{sub 2} in silicate liquids at elevated pressures and temperatures: A new experimental approach  

SciTech Connect

This study presents a new approach for determining the partial molar volume and its pressure derivative for a silicate liquid component through an experimental determination of the isothermal pressure dependence of the solubility in the liquid of a crystalline phase having the composition of the component. Because this approach allows the determination of partial molar volumes of liquid components at elevated pressure, it has the potential to detect pressure-induced structural changes associated with particular components in silicate liquid through their influence on partial molar volumes. To illustrate the approach, an experimental determination of the solubility of quartz in a rhyolitic liquid was used to determine the partial molar volume of SiO{sub 2} at pressures up to 35 kbar and a temperature of 1,350 C. The 1 bar partial molar volume for SiO{sub 2} determined in this way, 2.635 {+-} 0.009 J/bar, is slightly smaller than the 2.690 {+-} 0.006 J/bar determined by Lange and Carmichael (1987) (all uncertainties are 1{sigma}). The isothermal pressure dependence of the partial molar volume of SiO{sub 2} at 10 to 35 kbar is approximately one-half of the value determined by Kress and Carmichael (1991) at 1 bar. The high pressure determination can be reconciled with the existing 1 bar volume and compressibility data if the isothermal pressure dependence of the partial molar volume of SiO{sub 2} in silicate liquids decreases rapidly between 1 bar and 10 kbar, then remains approximately constant to at least 35 kbar.

Gaetani, G.A.; Asimow, P.D.; Stolper, E.M. [California Inst. of Tech., Pasadena, CA (United States). Div. of Geological and Planetary Sciences] [California Inst. of Tech., Pasadena, CA (United States). Div. of Geological and Planetary Sciences

1998-07-01

322

Dental caries in primary and permanent molars in 7-8-year-old schoolchildren evaluated with Caries Assessment Spectrum and Treatment (CAST) index  

PubMed Central

Background No reports on a caries pattern covering the full spectrum of the disease could be found in the literature. The aim of this study was to evaluate caries in primary and first permanent molars of 7-8-year-old Polish children by the Caries Assessment Spectrum and Treatment (CAST) index and to find whether there was any correlation between the caries stages in such teeth. Methods The study covered 284 7-8-year-old children from randomly selected schools in the Bialystok District, Poland. The prevalence of CAST categories was evaluated with regard to the first and second primary, and first permanent, molars. The Spearman’s rank correlation coefficient was used to explore the correlation of the distribution of CAST codes among the evaluated teeth. The level of statistical significance was established at p?molars, caries was observed in 14.8% to 17.3% of the molar and most lesions were scored at the non-cavitation level. Caries in primary molars was most often recorded at the stage of cavitated dentine lesion. Teeth with pulpal involvement, sepsis and extracted due to caries were found to be more prevalent in first, and then in second primary molars. A strong correlation was found between the status of teeth from the right and left sides of the oral cavity. The correlation of the status of first and second primary teeth was stronger for the left than for the right side of the mouth, r was 0.627 and 0.472 in maxilla and 0.513 and 0.483 in mandible (p?molars the correlation was assessed to be weak. With regard to the teeth situated in opposite jaws the study revealed that the correlations were moderate - r between 0.33 and 0.49. The intra-examiner reliability was established at 0.96 for the primary dentition and at 0.878 for permanent molars. Conclusion The strongest correlation found in the evaluated population concerned the distribution of caries in primary molars on the left side of the mouth. The study proved the usefulness of the CAST index in epidemiological surveys. PMID:24952612

2014-01-01

323

Potential Moderating Effects of Selenium on Mercury Uptake and Selenium:Mercury Molar Ratios in Fish From Oak Ridge and Savannah River Site - 12086  

SciTech Connect

Mercury contamination is an important remediation issue at the U.S. Department of Energy's (DOE) Oak Ridge Reservation and to a lesser extent at other DOE sites because of the hazard it presents, potential consequences to humans and eco-receptors, and completed pathways, to offsite receptors. Recent work has emphasized that selenium might ameliorate the toxicity of mercury, and we examine the selenium:mercury (Se:Hg) molar ratios in fish from Oak Ridge, and compare them to Se:Hg molar ratios in fish from the Savannah River. Selenium/mercury molar ratios varied considerably among and within fish species. There was considerable variation in the molar ratios for individual fish (as opposed to mean ratios by species) for freshwater fish from both sites. The inter-individual variation in molar ratios indicates that such that the molar ratios of mean Se and Hg concentrations may not be representative. Even for fish species with relatively low mercury levels, some individual fish have molar ratios less than unity, the value sometime thought to be protective. Selenium levels varied narrowly regardless of fish size, consistent with homeostatic regulation of this essential trace element. The data indicate that considerable attention will need to be directed toward variations and variances, as well as the mechanisms of the interaction of selenium and mercury, before risk assessment and risk management policies can use this information to manage mercury pollution and risk. Even so, if there are high levels of selenium in the fish from Poplar Creek on Oak Ridge, then the potential exists for some amelioration of adverse health effects, on the fish themselves, predators that eat them, and people who consume them. This work will aid DOE because it will allow managers and scientists to understand another aspect that affects fate and transport of mercury, as well as the potential effects of methylmercury in fish for human and ecological receptors. The variability within fish species, however, suggests that the relative Se:Hg molar ratios in fish are not stable enough to be used in risk assessment at this time. Nor is it known how much excess selenium is required to confer any degree of protectiveness. That is, in conducting risk assessments, it is not possible to determine the spread of ratios, which would be needed for probabilistic risk assessment. Significantly more fish samples per species are required to begin to generate data that would allow it use in risk assessment. Adding Se:Hg molar ratios seems to complicate risk assessment for the potential adverse effects of mercury exposure, and using mercury levels at this time remains the most viable option. (authors)

Burger, Joanna; Gochfeld, Michael; Donio, Mark [Division of Life Sciences, Rutgers University, 604 Allison Road, Piscataway, New Jersey 08854-8082 (United States); Environmental and Occupational Medicine, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854 (United States); Jeitner, Christian; Pittfield, Taryn [Division of Life Sciences, Rutgers University, 604 Allison Road, Piscataway, New Jersey 08854-8082 (United States); Consortium for Risk Evaluation with Stakeholder Participation (CRESP), Rutgers University and Vanderbilt University, Nashville, Tennessee 37235 (United States)

2012-07-01

324

Selenium and mercury molar ratios in commercial fish from New Jersey and Illinois: Variation within species and relevance to risk communication  

PubMed Central

There is an emerging consensus that people consuming large amounts of fish with selenium:mercury ratios below 1 may be at higher risk from mercury toxicity. As the relative amount of selenium increases compared to mercury, risk may be lowered, but it is unclear how much excess selenium is required. It would be useful if the selenium:mercury ratio was relatively consistent within a species, but this has not been the case in our studies of wild-caught fish. Since most people in developed countries and urban areas obtain their fish and other seafood commercially, we examined selenium:mercury molar ratios in commercial fish purchased in stores and fish markets in central New Jersey and Chicago. There was substantial interspecific and intraspecific variation in molar ratios. Across species the selenium:mercury molar ratio decreased with increasing mean mercury levels, but selenium variation also contributed to the ratio. Few samples had selenium:mercury molar ratios below 1, but there was a wide range in ratios, complicating the interpretation for use in risk management and communication. Before ratios can be used in risk management, more information is needed on mercury:selenium interactions and mutual bioavailability, and on the relationship between molar ratios and health outcomes. Further, people who are selenium deficient may be more at risk from mercury toxicity than others. PMID:23541437

Burger, Joanna; Gochfeld, Michael

2015-01-01

325

A new mammal skull from the Lower Cretaceous of China with implications for the evolution of obtuse-angled molars and ‘amphilestid’ eutriconodonts  

PubMed Central

We report the discovery of Juchilestes liaoningensis, a new genus and species of eutriconodont mammal from the Lujiatun Site of the Lower Cretaceous Yixian Formation (123.2 ± 1.0 Ma; Lower Aptian). The holotype preserves a partial skull and full dentition. Among eutriconodonts, its lower dentition is similar to taxa formerly assigned to the paraphyletic group of ‘amphilestids’. Some have considered ‘amphilestid’ molars to represent the structural intermediate between the lower molars of the ‘triconodont’ pattern of cusps in alignment and the fully triangulate and more derived therian molars. However, ‘amphilestid’ taxa were previously represented only by the lower dentition. Our study reveals, for the first time, the upper dentition and skull structure of an ‘amphilestid’, and shows that at least some eutriconodonts have an obtuse-angled cusp pattern on molars in middle positions of the long molar series. Its petrosal is similar to those of other eutriconodonts and spalacotheroid ‘symmetrodonts’. Our phylogenetic analyses suggest that (i) Juchilestes is most closely related to the Early Cretaceous Hakusanodon from Japan, in the same Eastern Asiatic geographic region; (ii) ‘amphilestids’ are not monophyletic; and (iii) eutriconodonts might not be a monophyletic group, although this hypothesis must be further tested. PMID:19726475

Gao, Chun-Ling; Wilson, Gregory P.; Luo, Zhe-Xi; Maga, A. Murat; Meng, Qingjin; Wang, Xuri

2010-01-01

326

Molar Absorptivity and Concentration-Dependent Quantum Yield of Fe(II) Photo-Formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Complexes  

NASA Astrophysics Data System (ADS)

Redox cycles of iron in the aquatic environment affect formation of reactive oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be important sources of photo-formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. We initiated a study to characterize Fe(II) photo-formation from Fe(III)-dicarboxylates with the concentration ranges that are relevant to the natural aquatic environment. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species. The molar absorptivity of Fe(III)-dicarboxylate species was obtained by UV-VIS spectrophotometer, and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained from photochemical experiments. These experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. We used initial concentrations of less than 10 micromolar Fe(III) to study the photochemical formation of Fe(II). Dicarboxylate compounds studied include oxalate, malonate, succinate, malate, and phthalate. We report molar absorptivity and concentration-dependent quantum yields of Fe(II) photo-formation of individual Fe(III)-dicarboxylates.

Hitomi, Y.; Arakaki, T.

2009-12-01

327

GENERAL: Low-temperature heat capacities and standard molar enthalpy of formation of N-methylnorephedrine C11H17NO(s)  

NASA Astrophysics Data System (ADS)

This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO(s) have been measured by a precision automated adiabatic calorimeter over the temperature range from T = 78 K to T = 400K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T = 342-364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T = 78-342 K and T = 364-400 K were fitted to two polynomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO(s) relative to the standard reference temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T = 298.15K was measured by means of an isoperibol precision oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.

Di, You-Ying; Wang, Da-Qi; Shi, Quan; Tan, Zhi-Cheng

2008-08-01

328

Supernumerary fourth molar and dental pathologies in a Chalcolithic individual from the El Mirador Cave site (Sierra de Atapuerca, Burgos, Spain).  

PubMed

We present a middle-aged Chalcolithic male with a supernumerary distomolar in the mandible. The prevalence of supernumerary teeth in present-day populations is low, ranging from 0.1% to 3.4%; most supernumerary teeth are documented in the anterior and molar regions of the maxilla in present populations. However, the prevalence of supernumerary molars in past populations is still unknown. Moreover, a complete pathological study has been done of this individual. Maxilla, mandible and teeth have been analyzed searching for dental pathologies. A cone-beam computed tomography (CBCT) analysis of mandibular and maxillary fragments was performed to check the evidence of hyperdontia. Dental wear and maxillary alveolar bone have been analyzed with environmental scanning electron microscope (ESEM) to improve the diagnosis of an abscess and evidence of tooth picking. This individual shows a left distomolar in the mandible without any evidence of other supernumerary teeth. The fourth molar is not associated with any congenital disease. However, this individual suffered severe dental wear and a variety of oral pathologies such as, dental decay, abscesses, pulpitis, periodontal disease, toothpicking marks in an upper molar, arthritis of the temporomandibular joint and malocclusion associated with high masticatory loads. To our knowledge, this individual from El Mirador Cave (Sierra de Atapuerca, Spain) shows the most ancient case of a fourth molar documented. The poor oral health of this individual corresponds to the general dental health of Chalcolithic populations. PMID:25456564

Ceperuelo, D; Lozano, M; Duran-Sindreu, F; Mercadé, M

2015-02-01

329

Preemptive effect of ketoprofen on postoperative pain following third molar surgery. A prospective, randomized, double-blinded clinical trial.  

PubMed

The authors examined whether ketoprofen administered 60 min before surgical extraction of the lower wisdom teeth provides effective postsurgical analgesia and reduces rescue analgesic intake compared with ketoprofen administered 60 min after surgery or placebo. The 96 patients were placed into three groups: pre-group (ketoprofen 60 min preoperatively); post-group (ketoprofen 60 min postoperatively); and no-group (placebo). Study interventions had a significant effect on pain sensations in the 12 h after surgery. The initial onset of pain was significantly delayed only in the post-group. Pain intensity at the first onset of pain was significantly lower only in the post-group. Patients in the pre- and post-groups required significantly less rescue analgesic than those in the no-group. Ketoprofen administered after third molar surgery provides more effective pain control than ketoprofen administered before the surgery or placebo. PMID:20338728

Kaczmarzyk, T; Wichlinski, J; Stypulkowska, J; Zaleska, M; Woron, J

2010-07-01

330

Fragility and molar volumes of non-stoichiometric chalcogenides: The crucial role of melt/glass homogenization  

NASA Astrophysics Data System (ADS)

Melt-fragility index (m) and glass molar volumes (Vm) of binary Ge-Se melts/glasses are found to change reproducibly as they are homogenized. Variance of Vm decreases as glasses homogenize, and the mean value of Vm increases to saturate at values characteristic of homogeneous glasses. Variance in fragility index of melts also decreases as they are homogenized, and the mean value of m decreases to acquire values characteristic of homogeneous melts. Broad consequences of these observations on physical behavior of chalcogenides melts/glasses are commented upon. The intrinsically slow kinetics of melt homogenization derives from high viscosity of select super-strong melt compositions in the Intermediate Phase that serve to bottleneck atomic diffusion at high temperatures.

Bhageria, R.; Gunasekera, K.; Boolchand, P.; Micoulaut, M.

2014-07-01

331

Investigation of Adsorption and Inhibitive Effect of Calixarene Derivative Newly Synthesized Towards C38 Steel in Molar HCl  

NASA Astrophysics Data System (ADS)

The focus of this study is to synthesize a new calixarene derivative namely calix[6]arene (C21) and to test its performance as corrosion inhibitor of C38 steel in molar HCl at 308 K. Polarization and weight loss measurements were used. Weight loss tests show that C21 retards until to stop corrosion phenomenon at 5 × 10-5 M. C21 is an excellent inhibitor and its inhibition efficiency increases with its concentration to reach 100% since 5 × 10-5 M. Polarization curves revealed that C21 affects both cathodic and anodic domains by decreasing current densities and then it may be classified as a mixed type inhibitor. The calixarene tested is adsorbed on the surface according to the Langmuir adsorption isotherm. Free enthalpy of adsorption reveals that C21 acts from chemisorption onto the steel surface.

Souane, R.; Kaddouri, M.; Bouklah, M.; Cheriaa, N.; Hammouti, B.; Vicens, J.

332

Degradation of high-molar-mass hyaluronan by ascorbate plus cupric ions: effects of D-penicillamine addition.  

PubMed

Pro- and anti-oxidative effects of an anti-rheumatoid drug, D-penicillamine (D-PN), on the kinetics of high-molar-mass hyaluronan (HA) degradation were monitored using the method of rotational viscometry. The degradation of the dissolved HA macromolecules was attained by applying the Weissberger's system comprising ascorbic acid plus cupric ions. Electron paramagnetic resonance (EPR) spectroscopy was used to identify the generated free radicals. The results obtained indicate that the initial anti-oxidative action of D-PN is followed by induction of pro-oxidative conditions due to the generation of reactive free radicals. It is speculated, however, that the latter situation may be considered as an advantageous property of D-PN. Hydroxyl radicals formed in this way may participate in decomposition of proteinases, which are believed to be responsible for the destruction of joint cartilage under rheumatoid arthritic conditions. PMID:19319875

Valachová, Katarína; Rapta, Peter; Kogan, Grigorij; Hrabárová, Eva; Gemeiner, Peter; Soltés, Ladislav

2009-03-01

333

The A.B.F.O. study of third molar development and its use as an estimator of chronological age.  

PubMed

Radiographs depicting third molars (M3s) have been used to estimate chronological age in juvenile and adult suspects, but accuracy of the method has been in question. This study provides age benchmarks for American whites (age range: 14 to 24 years) based on cases (n = 823) drawn from diplomates of the American Board of Forensic Odontologists in the United States and Canada. Maxillary M3 formation was slightly advanced over mandibular M3s, and root formation occurred earlier in males than females. Mean and median ages for M3 formation are tabled using Demirjian's eight-grade classification. Regression formulas and empirical probabilities are provided relative to the medicolegal question of whether an individual is at least 18 years of age. The M3 is the most variable tooth in the dentition, but situations arise where M3 formation is the only usable datum for age estimation. PMID:8454998

Mincer, H H; Harris, E F; Berryman, H E

1993-03-01

334

Three-dimensional evaluation of the mandibular third molars’ development in unilateral crossbite patients: A cone beam computed tomography study  

PubMed Central

Objectives: The aim was to investigate mandibular third molar (3M)'s maturation in the crossbite and normal sides by two- and three-dimensional analyses using cone beam computed tomography (CBCT). Materials and Methods: A retrospective study was performed using CBCT of 25 patients (16 females and 9 males; mean age: 16.8 ± 2.9 years) with unilateral posterior crossbite. The formation stages and the volume of the mandibular 3Ms were evaluated by means of CBCT data of the patients without knowing the crossbite side of the patients. Results: Statistically no significant differences were found in the development of the 3Ms between the crossbite and the control sides, whereas the volume of 3M was found to be less in the crossbite side than in the normal side (P = 0.021). Conclusions: A volume of 3M was found to be less in the crossbite side than in the normal side. PMID:25202221

Halicioglu, Koray; Celikoglu, Mevlut; Buyuk, Suleyman Kutalmis; Sekerci, Ahmet Ercan; Ucar, Faruk Izzet; Yavuz, Ibrahim

2014-01-01

335

Changes in the septohippocampal cholinergic system following removal of molar teeth in the aged SAMP8 mouse.  

PubMed

We investigated the effect of dysfunctional teeth on age-related changes in the septohippocampal cholinergic system by assessing acetylcholine (ACh) release and choline acetyltransferase (ChAT) activity in the hippocampus and ChAT immunohistochemistry in the medial septal nucleus and the vertical limb of the diagonal band in young-adult and aged SAMP8 mice after removal of their upper molar teeth (molarless condition). Aged molarless mice showed decreased ACh release and ChAT activity in the hippocampus and a reduced number of ChAT-immunopositive neurons in the medial septal nucleus compared to age-matched control mice, whereas these effects were not seen in young-adult mice. The results suggest that the molarless condition in aged SAMP8 mice may enhance an age-related decline in the septohippocampal cholinergic system. PMID:12110453

Onozuka, Minoru; Watanabe, Kazuko; Fujita, Masafumi; Tomida, Mihoko; Ozono, Satoru

2002-07-18

336

Fast Computation of Solvation Free Energies with Molecular Density Functional Theory: Thermodynamic-Ensemble Partial Molar Volume Corrections  

E-print Network

Molecular Density Functional Theory (MDFT) offers an efficient implicit- solvent method to estimate molecule solvation free-energies whereas conserving a fully molecular representation of the solvent. Even within a second order ap- proximation for the free-energy functional, the so-called homogeneous reference uid approximation, we show that the hydration free-energies computed for a dataset of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by two to three orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canoni- cal to the isobaric-isotherm ensemble that is pertinent to experiments. We show that this correction can be extended to 3D-RISM calculations, giving a sound theoretical justifcation to empirical partial molar volume corrections that have been proposed recently.

Volodymyr P. Sergiievskyi; Guillaume Jeanmairet; Maximilien Levesque; Daniel Borgis

2014-06-11

337

Molar microwear and dietary reconstructions of fossil cercopithecoidea from the Plio-Pleistocene deposits of South Africa.  

PubMed

The South African Plio-Pleistocene cave deposits have yielded a diverse cercopithecoid fauna. In this study, the possible dietary proclivities of these extinct species are examined using details of molar microwear. Although sample sizes are often small, wear patterns suggest possible temporal changes in the diets of Parapapio jonesi from Makapansgat to Sterkfontein, of Papio robinsoni from Sterkfontein to Swartkrans, and Cercopithecoides williamsi from Makapansgat to Sterkfontein to Swartkrans. However, there does not appear to have been a significant change in the dietary habits of Parapapio broomi over time. The microwear patterns of the two temporally successive congeners, Theropithecus darti and T. oswaldi show no significant differences from one another. The sympatric congeners, Parapapio broomi and Pp. jonesi, have microwear signatures that differ significantly at Makapansgat (Members 3 and 4) but not at Sterkfontein (Member 4). Finally, the microwear analyses suggest that the extinct cercopithecoid species did not necessarily have diets similar to those of their closest living relatives. PMID:15964607

El-Zaatari, Sireen; Grine, Frederick E; Teaford, Mark F; Smith, Heather F

2005-08-01

338

Cone beam computed tomography evaluation and endodontic management of permanent mandibular second molar with four roots: A rare case report and literature review  

PubMed Central

The morphological variation in the number of roots and root canals, especially in multi-rooted teeth is a constant challenge for diagnosis and successful endodontic therapy. Knowledge of the most common anatomic characteristics and their possible variations is fundamental. Although, endodontic management of four-rooted mandibular first molars have been observed on a few occasions in the literature, to the best of our knowledge four-rooted mandibular second molars having two mesial and two distal roots have not been reported. This paper highlights endodontic management of mandibular second molar with four roots (two mesial and two distal) with one canal in each root and its cone beam computed tomography (CBCT) evaluation which was primarily done for post treatment assessment for diagnosing post-endodontic complications, at the same time confirmed our radiographic diagnosis of this variation. This also helped us portraying the anatomy of this rare variation. PMID:25125856

Rajasekhara, Subhashini; Sharath Chandra, SM; Parthasarathy, Late Bharath

2014-01-01

339

Comparative evaluation of surgical outcome after removal of impacted mandibular third molars using a Piezotome or a conventional handpiece: a prospective study.  

PubMed

Our aim was to compare the use of a conventional rotary handpiece and a Piezosurgical unit for extraction of lower third molars. We studied 40 patients, who were allocated alternately to have the third molar removed with either the handpiece or the Piezosurgical unit. Pain, trismus, and oedema were evaluated at baseline and then postoperatively, together with paraesthesiae, on postoperative days 1, 3, 5, 7, and 15. Damage to surrounding tissue was checked on the same day whereas dry socket was evaluated from postoperative day 3 onwards. More patients complained of pain in the conventional group, they also required more analgesics, and they developed trismus more often than in the Piezosurgery group. There was also significantly more postoperative swelling in the conventional group. Patients were also evaluated using the subjective Postoperative Symptom Severity (PoSSe) scale. Our results suggest that apart from some inherent limitations with the Piezotome, it is a valuable alternative for extraction of third molars. PMID:22088359

Goyal, Manoj; Marya, Karan; Jhamb, Aakarsh; Chawla, Sonia; Sonoo, Priyanshu Ranjan; Singh, Veenita; Aggarwal, Anuj

2012-09-01

340

Influence of B4C to TTIP Molar Ratio on Synthesis of Nano Titanium Diboride Powders via Sol-Gel Method  

NASA Astrophysics Data System (ADS)

Titanium diboride (TiB2) has attracted great interests for its excellent mechanical properties, chemical resistance and good thermal and electrical conductivities. So it is widely applied as cutting tool composites, wear resistant parts, metal melting crucibles and electrode materials. This paper presents synthesis of nano titanium diboride powders via sol-gel method using a mixture of TTIP and B4C as precursors. In the hydrolysis step, B4C to TTIP molar ratio varied from 1.3 to 2.5. Solution samples stirred well and after aging and drying process, they were heat treated in an argon atmosphere. X-ray diffraction (XRD) patterns and Scanning electron microscopy (SEM) analysis showed that the percentage of synthesized TiB2 increased gradually as the molar ratio of B4C to TTIP reached to 2.3, afterward increasing the B4C to TTIP molar ratio caused decreasing of titanium diboride percentage.

Sinaei Pour Fard, Hamed; Baharvandi, Hamidreza; Abdizadeh, Hossein

341

A comparative study of cone-beam computed tomography and digital periapical radiography in detecting mandibular molars root perforations  

PubMed Central

Purpose The aim of this in vitro study was to determine the sensitivity and specificity of cone-beam computed tomography (CBCT) and digital periapical radiography in the detection of mesial root perforations of mandibular molars. Materials and Methods In this in vitro study, 48 mandibular molars were divided into 4 groups. First, the mesial canals of all the 48 teeth were endodontically prepared. In 2 groups (24 teeth each), the roots were axially perforated in the mesiolingual canal 1-3 mm below the furcation region, penetrating the root surface ("root perforation"). Then, in one of these 2 groups, the mesial canals were filled with gutta-percha and AH26 sealer. Mesial canals in one of the other 2 groups without perforation (control groups) were filled with the same materials. The CBCT and periapical radiographs with 3 different angulations were evaluated by 2 oral and maxillofacial radiologists. The specificity and sensitivity of the two methods were calculated, and P<0.05 was considered significant. Results The sensitivity and specificity of CBCT scans in the detection of obturated root canal perforations were 79% and 96%, respectively, and in the case of three-angled periapical radiographs, they were 92% and 100%, respectively. In non-obturated root canals, the sensitivity and specificity of CBCT scans in perforation detection were 92% and 100%, respectively, and for three-angled periapical radiographs, they were 50% and 96%, respectively. Conclusion For perforation detection in filled-root canals, periapical radiography with three different horizontal angulations would be trustworthy, but it is recommended that CBCT be used for perforation detection before obturating root canals. PMID:24944960

Haghanifar, Sina; Moudi, Ehsan; Mesgarani, Abbas; Bijani, Ali

2014-01-01

342

Brief communication: comparing loading scenarios in lower first molar supporting bone structure using 3D finite element analysis.  

PubMed

Finite element analysis (FEA) is a widespread technique to evaluate the stress/strain distributions in teeth or dental supporting tissues. However, in most studies occlusal forces are usually simplified using a single vector (i.e., point load) either parallel to the long tooth axis or oblique to this axis. In this pilot study we show how lower first molar occlusal information can be used to investigate the stress distribution with 3D FEA in the supporting bone structure. The LM(1) and the LP(2) -LM(1) of a dried modern human skull were scanned by ?CT in maximum intercuspation contact. A kinematic analysis of the surface contacts between LM(1) and LP(2) -LM(1) during the power stroke was carried out in the occlusal fingerprint analyzer (OFA) software to visualize contact areas during maximum intercuspation contact. This information was used for setting the occlusal molar loading to evaluate the stress distribution in the supporting bone structure using FEA. The output was compared to that obtained when a point force parallel to the long axis of the tooth was loaded in the occlusal basin. For the point load case, our results indicate that the buccal and lingual cortical plates do not experience notable stresses. However, when the occlusal contact areas are considered, the disto-lingual superior third of the mandible experiences high tensile stresses, while the medio-lingual cortical bone is subjected to high compressive stresses. Developing a more realistic loading scenario leads to better models to understand the relationship between masticatory function and mandibular shape and structures. Am J Phys Anthropol, 2012. © 2011 Wiley Periodicals, Inc. PMID:21952986

Benazzi, Stefano; Kullmer, Ottmar; Grosse, Ian R; Weber, Gerhard W

2012-01-01

343

Morphological and topographical characteristics of posterior supernumerary molar teeth: An epidemiological study on 25,186 subjects  

PubMed Central

Objectives: To investigate the prevalence , gender difference , arch , morphology and position within the arch of supernumerary molar (SM) teeth in a referred Italian Caucasian population. Study Design: Records of 25,186 young patients were evaluated. Only data related to supernumerary teeth in the posterior region of the jaws were analyzed. The diagnosis of hyperdontia was formulated during the clinical and radiological examinations based on panoramic radiographs. Statistical analysis was conducted at level of subjects in the assessment of prevalence of SMs and sex ratio. Statistical analysis was conducted at level of teeth according to their morphological and topographic characteristics. The analysis of association between supernumerary morphology and arch, between supernumerary position and arch and between morphology and position was performed using the ?2 test (P? 0.05). Results: 61 posterior supernumerary teeth were found in 45 patients. The male to female ratio was 2.5:1 ;the mean age was 21.23 (IC:95%).The SMs were found more frequently in the maxilla (62.3%) than in the mandible; supernumerary teeth (60.7%) were more frequent than supplemental teeth. The SMs were mostly of tuberculate shape (56.8%) and paramolars teeth (64.9%) were more common than distomolars. 54% of teeth were erupted in the arch. No statistically significant relationship were found between the supernumerary teeth shape and the arch (P= 0.087) , between supernumerary teeth position and the arch (P=0.511) and between morphology and position (P=0.216). Conclusions: Epidemiological studies related to supernumerary teeth can be useful to clinicians in the early diagnosis of this anomaly. In this retrospective study the prevalence of SMs was 0.18%. SMs were more frequent in males and in the maxilla. Supernumerary were more frequent than supplemental; the conical morphology and paramolar position were the most common shape and position. Key words:Hyperdontia, prevalence, supernumerary molars, distomolar, paramolar. PMID:25129242

Altieri, Federica; Giansanti, Matteo; Di-Giorgio, Roberto; Calasso, Sabrina

2014-01-01

344

Pre- and Postnatal Determinants of Deciduous Molar Hypomineralisation in 6-Year-Old Children. The Generation R Study  

PubMed Central

Background Deciduous Molar Hypomineralisation (DMH) and Molar Incisor Hypomineralisation (MIH) are common developmental disturbances in pediatric dentistry. Their occurrence is related. The same determinants as suggested for MIH are expected for DMH, though somewhat earlier in life. Perinatal medical problems may influence the prevalence of DMH but this has not been studied sufficiently. Objective This study aimed to identify possible determinants of DMH in a prospective cohort study among 6-year-old children. Study Design This study was embedded in the Generation R Study, a population-based prospective cohort study from fetal life until young adulthood. The the data were used to identify the determinants of DMH. Clinical photographs of clean, moist teeth were taken with an intra-oral camera in 6690 children (mean age 6.2 years; 49.9% girls). Data on possible determinants that had occurred during pregnancy and/or the child's first year of life were on the basis of manual standardized measurements (like length and weight) and questionnaires. Multivariate analyse with backward and forward selection was performed. Results A number of factors in the pre-, peri- and postnatal phase were found to be associated with DMH. After multivariate logistic regression analyses, Dutch ethnic background, low birth weight, maternal alcohol consumption during pregnancy, and fever episodes in the first year of the child's life were found to play a role in the development of DMH in 6-year-old children. Conclusion This study shows that Dutch ethnicity, low birth weight, alcohol consumption by the mother during pregnancy and any fever in the first year of the child's life are associated with DMH. Not only childhood factors but also prenatal lifestyle factors need to be taken into account when studying determinants for DMH. PMID:24988443

Elfrink, Marlies E. C.; Moll, Henriette A.; Kiefte-de Jong, Jessica C.; Jaddoe, Vincent W. V.; Hofman, Albert; ten Cate, Jacob M.; Veerkamp, Jaap S. J.

2014-01-01

345

Na/Cl molar ratio changes during a salting cycle and its application to the estimation of sodium retention in salted watersheds  

NASA Astrophysics Data System (ADS)

Using soil column experiments and data from natural watersheds, this paper analyzes the changes in Na/Cl molar ratios during a salting cycle of aqueous-soil systems. The soil column experiments involved introducing NaCl salt at various initial concentrations into multiple soil columns. At the start of a salting cycle in the column experiments, sodium was adsorbed more than chloride due to cation exchange processes. As a result, the initial Na/Cl molar ratio in column effluent was lower than 1, but increased thereafter. One-dimensional PHREEQC geochemical transport simulations also were conducted to further quantify these trends under more diverse scenarios. The experimentally determined Na/Cl molar ratio pattern was compared to observations in the annual salting cycle of four natural watersheds where NaCl is the dominant applied road deicing salt. Typically, Na/Cl molar ratios were low from mid-winter to early spring and increased after the bulk of the salt was flushed out of the watersheds during the summer, fall and early winter. The established relationship between the Na/Cl molar ratios and the amount of sodium retention derived from the column experiments and computer simulations present an alternative approach to the traditional budget analysis method for estimating sodium retention when the experimental and natural watershed patterns of Na/Cl molar ratio change are similar. Findings from this study enhance the understanding of sodium retention and help improve the scientific basis for future environmental policies intended to suppress the increase of sodium concentrations in salted watersheds.

Sun, Hongbing; Huffine, Maria; Husch, Jonathan; Sinpatanasakul, Leeann

2012-08-01

346

Partial Molar Volumes of Some of ?-Amino Acids in Binary Aqueous Solutions of MgSO 4 ·7H 2 O at 298.15 K  

Microsoft Academic Search

The apparent molar volume, V\\u000a o\\u000a ?, 2, of glycine, alanine, ?-amino-n-butyric acid, valine and leucine have been determined in aqueous solutions of 0.25, 0.5 and 1.0 mol?dm?3 magnesium sulfate, and the partial specific volume from density measurements at 298.15 K. These data have been used to calculate the infinite dilution apparent molar volume, V\\u000a o\\u000a 2,m\\u000a , group contribution

Bairagi C. Mallick; Nand Kishore

2006-01-01

347

Effect of the local administration of betamethasone on pain, swelling and trismus after impacted lower third molar extraction. A randomized, triple blinded, controlled trial  

PubMed Central

Objectives: The aim of this study is to compare the analgesic and anti-inflammatory effects of the local postoperative administration of a single 12-mg dose of betamethasone after the surgical removal of impacted lower third molars. Study Design: A split-mouth, triple-blind, randomized, placebo-controlled clinical trial of 25 patients requiring the surgical removal of symmetrical lower third molars was performed. In the experimental side, a 12-mg dose of betamethasone was administered submucosally after the surgical procedure, while in the control side a placebo (sterile saline solution) was injected in the same area. To assess postoperative pain, visual analogue scales and the consumption of rescue analgesic were used. The facial swelling and trismus were evaluated by measuring facial reference distances and maximum mouth opening. Results: There were no significant differences between the two study groups regarding postoperative pain, facial swelling and trismus. Conclusions: The injection of a single dose of betamethasone does not seem to reduce pain, facial swelling and trismus after impacted lower third molar removal when compared to placebo. Key words:Third molar extraction, corticosteroids, betamethasone. PMID:24121915

Marques, José; Pié-Sánchez, Jordi; Valmaseda-Castellón, Eduard; Gay-Escoda, Cosme

2014-01-01

348

The effect of Cu/Zn molar ratio on CO2 hydrogenation over Cu/ZnO/ZrO2/Al2O3 catalyst  

NASA Astrophysics Data System (ADS)

Catalytic hydrogenation of carbon dioxide (CO2) to methanol is an attractive way to recycle and utilize CO2. A series of Cu / ZnO / Al2O3/ZrO2 catalysts (CZAZ) containing different molar ratios of Cu/Zn were prepared by the co-precipitation method and investigated in a stirred slurry autoclave system. The catalysts were characterized by temperature-programmed reduction (TPR), field emission scanning electron microscopy-energy dispersive analysis (FESEM-EDX), X-ray diffraction (XRD) and N2 adsorption-desorption. Higher surface area, SABET values (42.6-59.9 m2/g) are recorded at low (1) and high (5) Cu/Zn ratios with the minimum value of 35.71 m2/g found for a Cu/Zn of 3. The reducibility of the metal oxides formed after calcination of catalyst samples was also affected due to change in metal-support interaction. At a low reaction temperature of 443 K, total gas pressure of 3.0 MPa and 0.1 g/mL of the CZAZ catalyst, the selectivity to methanol decreased as the Cu/Zn molar ratio increased, and the maximum selectivity of 67.73 was achieved at Cu/Zn molar ratio of 1. With a reaction time of 3h, the best performing catalyst was CZAZ75 with Cu/Zn molar ratio of 5 giving methanol yield of 79.30%.

Shaharun, Salina; Shaharun, Maizatul S.; Mohamad, Dasmawati; Taha, Mohd F.

2014-10-01

349

Chain architecture of LDPE as a function of molar mass using size exclusion chromatography and multi-angle laser light scattering (SEC-MALLS)  

Microsoft Academic Search

Long chain branching causes a decrease in molecular size and hence in the radius of gyration and the hydrodynamic radius, as compared to polymers having a linear structure and having the same molar mass. In principle there is a simple relation between the ratio of the radii of gyration and the hydrodynamic radii: g? = gb. At constant temperature and

P. Tackx; J. C. J. F. Tacx

1998-01-01

350

Method for determining the amylose content, molecular weights, and weight- and molar-based distributions of degree of polymerization of amylose and fine-structure of amylopectin  

Microsoft Academic Search

Cooked rice texture and other aspects of rice starch functionality are influenced by amylose and amylopectin content and structure. A method is described that uses high performance size exclusion chromatography coupled with multiangle laser light scattering and refractive index detectors to determine amylose content, molecular mass of amylose and the weight- and molar-based distributions of degree of polymerization (DP) of

Ming-Hsuan Chen; Christine J. Bergman

2007-01-01

351

Molar Absorptivity and Quantum Yield of Fe(II) Photo-formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Comlexes  

NASA Astrophysics Data System (ADS)

Fe(III)/Fe(II) cycle in the environment affects formation of active oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be an important source of photo-chemically formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species in the aqueous solutions of Fe(III)-dicarboxylate complexes. The molar absorptivity and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained by UV-VIS spectrophotometer and photochemical experiments, and these experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. Dicarboxylate compounds studied were oxalate, malonate, succinate, malate, and phthalate.

Hitomi, Y.; Arakaki, T.

2009-04-01

352

Effectiveness of 1% versus 0.2% chlorhexidine gels in reducing alveolar osteitis from mandibular third molar surgery: A randomized, double-blind clinical trial  

PubMed Central

Purpose: Alveolar osteitis (AO) is the most common postoperative complication of dental extractions. The purpose of this study was to compare the effectiveness of 1% versus 0.2% chlorhexidine (CHX) gel in reducing postoperative AO after surgical extraction of mandibular third molars, and assess the impact of treatment on the Oral HealthRelated Quality of Life (OHRQoL). Material and Methods: This clinical study was a randomized, double-blind clinical trial. Eighty eight patients underwent surgical extraction of one retained mandibular third molar with the intra-alveolar application of 0.2% CHX gel. Afterwards, they were assigned to one of two groups: 1% CHX gel (n=42) or 0.2% CHX gel (n=46). The patients applied the gel twice a day to the wound for one week. All patients were evaluated for AO. Results: In the 0.2% CHX gel group, 13% of AO incidence was found, while in the 1% CHX gel group, AO incidence was 7%, a difference that was not statistically significant. Variables such as sensation of pain and inflammation at baseline and during one week, as well as OHRQoL of the patients at 24 hours and 7 days post-extraction, gave no statistically significant differences. Conclusions: There are no significant differences in AO after surgical extraction of mandibular third molars, when comparing applying 1% CHX gel twice a day for 7 days with 0.2% CHX gel. Key words:Alveolar osteitis, chlorhexidine gel, third molar. PMID:23722126

Bravo-Pérez, Manuel; Sánchez-López, José D.; Muñoz-Soto, Esther; Romero-Olid, María N.; Baca-García, Pilar

2013-01-01

353

An Ex Vivo Comparison of Digital Radiography, Cone Beam and Micro Computed Tomography in the Detection of the Number of Canals in the Mesiobuccal Roots of Maxillary Molars  

PubMed Central

Introduction The purpose of this study was to compare digital periapical and cone beam computed tomography (CBCT) images to determine the number of canals in the mesiobuccal root (MB) of maxillary molars and to compare these counts to micro CT (?CT), which was also used to determine canal configuration. Methods Digital periapical (RVG 6100), CBCT (9000 3D) and ?CT images (the reference standard) were obtained of 18 hemi-maxillas. With periapical and CBCT images, 2 endodontists independently counted the number of canals in each molar and repeated counts 2 weeks later. Teeth were extracted, scanned with ?CT, and 2 additional endodontists, by consensus, determined the number and configuration of canals. The Friedman test was used to test for differences. Results In mesiobuccal roots, 2 canals were present in 100% (13/13) of maxillary first and 57% (8/14) second molars, and 69% (9/13) and 100% (8/8) of these exited as two or more foramina. There was no difference in canal counts for original and repeat reads by the two observers with periapicals (P = 0.06) and with CBCT (P = 0.88) and no difference when CBCT counts were compared with ?CT counts (P = 0.52); however, when periapical counts were compared with ?CT counts there was a significant difference (P = 0.04). Conclusions For cadaver maxillary molars, ?CT canal counts were significantly different from digital periapical radiograph counts but not different from Carestream 9000 3D CBCT counts. PMID:23791260

Domark, Jeffrey D.; Hatton, John F.; Benison, Roxanne P.; Hildebolt, Charles F.

2014-01-01

354

Micro-computed tomography analysis of changes in the periodontal ligament and alveolar bone proper induced by occlusal hypofunction of rat molars  

PubMed Central

Objective To three-dimensionally elucidate the effects of occlusal hypofunction on the periodontal ligament and alveolar bone proper of rat molars by micro-computed tomography (micro-CT). Methods Occlusal function in the molar area was restricted by attaching an anterior bite plate on the maxillary incisors and a metal cap on the mandibular incisors of 5-week-old male Wistar rats for 1 week. The periodontal ligament space and alveolar bone proper around roots of the mandibular first molar were assessed by histology and micro-CT. Results The periodontal ligament space was narrower and the alveolar bone proper was sparser and less continuous in the hypofunction group than in the control group. Further, both the volume of the periodontal ligament and the volumetric ratio of the alveolar bone proper to the total tissue in the region of interest were significantly lower in the hypofunction group (p < 0.05). Conclusions Occlusal hypofunction induces atrophic changes in the periodontal ligament and alveolar bone proper of rat molars. PMID:25309866

Hosomichi, Jun; Nakamura, Saeko; Ono, Takashi

2014-01-01

355

MOLAR FRACTIONS OF HIGH MOLECULAR WEIGHT GLUTENINS SUBUNITS ARE STABLE WHEN WHEAT IS GROWN UNDER VARIOUS MINERAL NUTRITION AND TEMPERATURE REGIMENS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Molar ratios of the high molecular weight glutenin subunits (HMW-GS) were determined for flour from bread wheat (Triticum aestivum L. cv Butte86) produced under 13 different combinations of temperature, water and mineral nutrition. Despite great differences in duration of grain fill, total protein ...

356

Excess molar heat capacities and excess molar volumes of (an n -alkylalkanoate + 2,2,4-trimethylpentane, or 2,2,4,4,6,8,8-heptamethylnonane) at T = 298.15 K  

Microsoft Academic Search

Excess molar heat capacities Cp, mEat constant pressure have been measured, as a function of mole fraction x at the temperature T= 298.15 K and atmospheric pressure, for eight liquid mixtures consisting of an n -alkylalkanoate and a highly-branched alkane {i.e. 2,2,4-trimethylpentane (isooctane) and 2,2,4,4,6,8,8-heptamethyl- nonane}: [xHCOO(CH2)3CH3+ (1 ?x){(CH3)3CCH2CH(CH3)2, or (CH3)3CCH2C(CH3)2CH2CH(CH3)CH2C(CH3)3} ], {xCH3COOCH2CH3+(1 ?x)(CH3)3CCH2CH(CH3)2}, {xCH3COO(CH2)3CH3+ (1 ?x)(CH3)3CCH2CH(CH3)2}, {xCH3CH2COOCH3+ (1 ?x)(CH3)3CCH2CH(CH3)2},

Emmerich Wilhelm

1999-01-01

357

A scanning electron-microscopic, stereo-pair study of methacrylate corrosion casts of the mouse palatal and molar periodontal microvasculature.  

PubMed

Microvascular beds of the palate, gingiva and periodontal ligament had interconnected but distinct, regional patterns. The palatal vasculature reflected mucosal-crest morphology: crestal capillary vessels of the rugae anastomosed with sagitally-orientated rows of 8 microns capillary loops, and, in the inter-rugal troughs, these formed a flat plexus overlying collecting veins more than 100 microns in diameter. Maxillary and mandibular molar ligaments had similar microvascular patterns. The molar gingiva had a circular, outer capillary and inner venous system linked by radial anastomoses. The outer (7 microns) capillaries enclosed the three molars in a continuous horizontal loop coursing beneath the crestal epithelium; the inner (10-15 microns) venous vessels encircled each molar just below the epithelial attachment. Glomerulus-like vascular formations, with an arterial and venous stalk, were associated with the inner circular system and extended toward the crevicular epithelium. Axially aligned, post-capillary, periodontal-ligament vessels (21 microns) anastomosed with the inner circular system, forming different patterns in the occlusal, middle and apical thirds. The apical pattern comprised an enveloping plexus of anastomosing venous vessels supplied by arterio-venous shunts; similar shunts were present throughout the ligament. The microvascular bed of the mandibular inter-radicular ligament was characterized by the presence of a large venous ampulla measuring 60 by 200 microns. Some regions of the ligament microvasculature drained via the medullary vessels into 50 microns-diameter venules located interdentally deep to the molar apices. Volumetrically, the ligament microvascular bed was predominantly of post-capillary venules, and morphologically, a paired arterial and venous system was not demonstrated. PMID:3479097

Wong, R S; Sims, M R

1987-01-01

358

Digital radiographic evaluation of mandibular third molar for age estimation in young adults and adolescents of South Indian population using modified Demirjian's method  

PubMed Central

In recent years, it has become increasingly important to determine the age of living people for a variety of reasons, including identifying criminal and legal responsibility and for many other social events such as birth certificate, marriage, beginning a job, joining the army and retirement Objectives: The aim of this study was to assess the developmental stages of mandibular third molar for estimation of dental age (DA) in different age groups and to evaluate the possible correlation between DA and chronological age (CA) in South Indian population. Materials and Methods: Digital orthopantomography of 330 subjects (165 males, 165 females) who fit the study and the criteria were obtained. Assessment of mandibular third molar development was performed using Demirjian et al., modified method and DA was assessed using tooth specific stages. Results and Discussion: The present study showed a significant correlation between DA and CA in both males and females. Third molar development commenced around 9 years and root completion takes place around 18.9 years in males and in females 9 years and 18.6 years respectively. Demirjian modified method underestimated the mean age of males by 0.8 years and females by 0.5 years and also showed that females mature earlier than males in selected population. Conclusion: Digital radiographic assessment of mandibular third molar development can be used to generate mean DA using Demirjian modified method and also the estimated age range for an individual of unknown CA. Since the Demirjian method is based on French-Canadian population, to enhance the accuracy of forensic age estimates based on third molar development, the use of population-specific standards is recommended. PMID:25177143

Mohammed, Rezwana Begum; Koganti, Ravichandra; Kalyan, Siva V.; Tircouveluri, Saritha; Singh, Johar Rajvinder; Srinivasulu, Enganti

2014-01-01

359

Mercury and selenium levels, and selenium:mercury molar ratios of brain, muscle and other tissues in bluefish (Pomatomus saltatrix) from New Jersey, USA  

PubMed Central

A number of contaminants affect fish health, including mercury and selenium, and the selenium: mercury molar ratio. Recently the protective effects of selenium on methylmercury toxicity have been publicized, particularly for consumption of saltwater fish. Yet the relative ameliorating effects of selenium on toxicity within fish have not been examined, nor has the molar ratio in different tissues, (i.e. brain). We examined mercury and selenium levels in brain, kidney, liver, red and white muscle, and skin and scales in bluefish (Pomatomus saltatrix) from New Jersey to determine whether there were toxic levels of either metal, and we computed the selenium: mercury molar ratios by tissues. Total mercury averaged 0.32 ± 0.02 ppm wet weight in edible muscle and 0.09 ± 0.01 ppm in brain. Selenium concentration averaged 0.37 ± 0.03 in muscle and 0.36 ± 0.03 ppm in brain. There were significant differences in levels of mercury, selenium, and selenium: mercury molar ratios, among tissues. Mercury and selenium levels were correlated in kidney and skin/scales. Mercury levels were highest in kidney, intermediate in muscle and liver, and lowest in brain and skin/scales; selenium levels were also highest in kidney, intermediate in liver, and were an order of magnitude lower in the white muscle and brain. Mercury levels in muscle, kidney and skin/scales were positively correlated with fish size (length). Selenium levels in muscle, kidney and liver were positively correlated with fish length, but in brain; selenium levels were negatively correlated with fish length. The selenium: mercury molar ratio was negatively correlated with fish length for white muscle, liver, kidney, and brain, particularly for fish over 50 cm in length, suggesting that older fish experience less protective advantages of selenium against mercury toxicity than smaller fish, and that consumers of bluefish similarly receive less advantage from eating larger fish. PMID:23202378

Burger, Joanna; Jeitner, Christian; Donio, Mark; Pittfield, Taryn; Gochfeld, Michael

2015-01-01

360

Interspecific and intraspecific variation in selenium:mercury molar ratios in saltwater fish from the Aleutians: Potential protection on mercury toxicity by selenium  

PubMed Central

A number of factors affect the consumption risk from mercury in fish, including mercury levels, seasonal patterns of mercury concentrations, human consumption patterns, and sensitive populations (e.g. pregnant women, fetuses, young children, and yet unknown genetic factors). Recently the protective effects of selenium on methylmercury toxicity have been publicized, particularly for saltwater fish. We examine levels of mercury and selenium in several species of fish and seabirds from the Aleutians (Alaska), determine selenium:mercury molar ratios, and examine species-specific and individual variation in the ratios as a means of exploring the use of the ratio in risk assessment and risk management. Variation among species was similar for mercury and selenium. There was significant inter-specific and intraspecific variation in selenium:mercury molar ratios for fish, and for birds. The mean selenium:mercury molar ratios for all fish and bird species were above 1, meaning there was an excess of selenium relative to mercury. It has been suggested that an excess of selenium confers some protective advantage for salt water fish, although the degree of excess necessary is unclear. The selenium:mercury molar ratio was significantly correlated negatively with total length for most fish species, but not for dolly varden. Some individuals of Pacific cod, yellow irish lord, rock greenling, Pacific halibut, dolly varden, and to a lesser extent, flathead sole, had selenium:mercury ratios below 1. No bird muscle had an excess of mercury (ratio below 1), and only glaucous-winged gull and pigeon guillemot had ratios between 1 and 5. There was a great deal of variation in selenium:mercury molar ratios within fish species, and within bird species, making it difficult and impractical to use these ratios in risk assessment or management, for fish advisories, or for consumers, particularly given the difficulty of interpreting the ratios. PMID:22664537

Burger, Joanna; Gochfeld, Michael; Jeitner, Christian; Donio, Mark; Pittfield, Taryn

2014-01-01

361

Mercury and selenium in European catfish (Silurus glanis) from Northern Italian Rivers: Can molar ratio be a predictive factor for mercury toxicity in a top predator?  

PubMed

The study of mercury and selenium bioaccumulation in fish is crucially important for evaluating the extent of contamination in freshwater environments, and the possible health risk posed for humans when the antagonistic interactions of these two elements are considered. Several factors affect the risk of mercury intake from fish consumption, including mercury levels, human consumption patterns, and sensitive populations (e.g., pregnant women, foetuses, young children and unknown genetic factors). The protective effects of selenium on mercury toxicity have been extensively publicised in recent years, particularly targeting fish consumers. In this study, mercury (Hg) and selenium (Se) concentrations were determined in the muscle of European catfish (Silurus glanis) collected from North Italian Rivers. Differences in mercury and selenium levels, as a function of size, gender and location were investigated. Hg was strongly related to length, gender and location, while Se levels are not dependent on fish size or location. The mean Se/Hg molar ratio was strongly affected by location, and significantly related to length and age. Selenium was in molar excess of mercury in all sites, with a rank order of mean Se/Hg molar ratio of the Parma River (2.55)>Po River (1.71)>Tanaro River (1.66)>Bormida River (1.36). However, in 37% of analyzed samples, Hg exceeded the maximum level set by 1881/2006/EC and 629/2008/EC in fish muscle. The molar ratio of Se/Hg was <1 only in the presence of significantly high Hg levels (>0.5mg/kg), and therefore the mean molar ratio cannot be considered as a safety criterion in top predator fish. PMID:25460744

Squadrone, S; Benedetto, A; Brizio, P; Prearo, M; Abete, M C

2015-01-01

362

Comparison of the effect of naproxen, etodolac and diclofenac on postoperative sequels following third molar surgery: A randomised, double-blind, crossover study  

PubMed Central

Objectives: To compare the three non-steroidal anti-inflammatory agents (NSAIDs) diclofenac potassium, etodolac and naproxen sodium in relation to pain, swelling and trismus following impacted third molar surgery. Study Design: The study was a randomized and a double-blinded study which included 42 healthy young individuals with impacted third molars and bone retention. Patients were randomly assigned to 3 groups (n: 14) to which diclofenac potassium, naproxen sodium and etodolac were administered orally an hour before the operation. Impacted third molars were surgically extracted with local anaesthesia. Visual analog scales (VAS) were used to assess the pain in the 6th, 12th hours and on the 1st, 2nd, 3rd, 5th, and 7th days postoperatively. Swelling was evaluated using ultrasound (US) and mouth opening (trismus) was measured with a composing stick pre and post operatively on the 2nd and 7th days respectively. Results: Regarding pain alleviation, diclofenac potassium was better than naproxen sodium and naproxen sodium was better than etodolac but these differences were not statistically significant. US measurements showed that the swelling on postoperative 2nd day was significantly lowest with diclofenac potassium as compared to others (p= 0.027) while naproxen sodium and etodolac acted similarly (p=0.747). No difference was noted regarding trismus in any of the groups. Conclusions: NSAIDs (diclofenac, naproxen and etodolac) are somehow similarly effective for controlling pain and trismus following extraction of mandibular third molars but diclofenac potassium surpasses others in reduction of swelling. Key words:Diclofenac potassium, naproxen sodium, etodolac, impacted third molar surgery, pain, swelling, trismus. PMID:24316711

Akbulut, Nihat; Atakan, Cemal; Çölok, Gülümser

2014-01-01

363

Modifications in Canal Anatomy of Curved Canals of Mandibular First Molars by two Glide Path Instruments using CBCT  

PubMed Central

Background: The creation of glide path reduces the risk of instrument breakage. Glide path is created before using NiTi rotary instrumentation Aim: This study compared the changes in the root canal anatomy after creation of glide path using Path Files (PF) and V Glide Path 2 (VGP2) using Cone Beam Computed Tomography (CBCT). Materials and Methods: Hundred extracted mandibular first molars with curved mesial roots, curvature angles ranging within 20-30 degrees were assigned into two groups (n = 50 each). Glide path was prepared using PF (Group I) and VGP2 (Group II). CBCT images were obtained before and after instrumentation. The technical outcomes were compared at 0, 1, 2, 3, 5 and 7mm intervals. The data was analyzed using t-test and Chi-square test. Result: There was a statistical difference between the root canal curvatures and working time between the two groups (p < 0.05). Canals transported towards the distal side in Group II but there was a slight mesial transportation in Group I at 0mm. Group I exhibited a better centric ability except at 1mm interval (p > 0.05). The changes in the volume were statistically significant only at 2mm interval (p < 0.05). The difference in the cross sectional area was not statistically significant at any interval (p > 0.05). Conclusion: Within the limits of this study the rotary Nickel Titanium Path Files appeared to be suitable instruments for safe and easy creation of glide path.

Manchanda, Nayasha

2014-01-01

364

Method for determining molar concentrations of metabolites in complex solutions from two-dimensional 1H-13C NMR spectra.  

PubMed

One-dimensional (1D) (1)H nuclear magnetic resonance (NMR) spectroscopy is used extensively for high-throughput analysis of metabolites in biological fluids and tissue extracts. Typically, such spectra are treated as multivariate statistical objects rather than as collections of quantifiable metabolites. We report here a two-dimensional (2D) (1)H-(13)C NMR strategy (fast metabolite quantification, FMQ, by NMR) for identifying and quantifying the approximately 40 most abundant metabolites in biological samples. To validate this technique, we prepared mixtures of synthetic compounds and extracts from Arabidopsis thaliana, Saccharomyces cerevisiae, and Medicago sativa. We show that accurate (technical error 2.7%) molar concentrations can be determined in 12 min using our quantitative 2D (1)H-(13)C NMR strategy. In contrast, traditional 1D (1)H NMR analysis resulted in 16.2% technical error under nearly ideal conditions. We propose FMQ by NMR as a practical alternative to 1D (1)H NMR for metabolomics studies in which 50-mg (extract dry weight) samples can be obtained. PMID:17985927

Lewis, Ian A; Schommer, Seth C; Hodis, Brendan; Robb, Kate A; Tonelli, Marco; Westler, William M; Sussman, Michael R; Markley, John L

2007-12-15

365

Phase boundaries and molar volumes of high-temperature and high-pressure phase V of LiBH4  

NASA Astrophysics Data System (ADS)

Raman measurements up to 14 GPa and 570 K and powder x-ray diffraction measurement from 4 to 28 GPa at 510 K were used to investigate the high-temperature and high-pressure phases of LiBH4. The B-H stretching Raman bands in high-temperature and high-pressure phase V were observed as one broad peak, which would arise from the disordered structure. The rotation of BH4 - ions has also been observed by a quantum MD calculation. The results are consistent with the reported structure of phase V that is known to be an orientationally disordered structure. The Raman measurements indicated that the phase boundary between phases I and V and that between phases III and V have a negative slope against pressure. The negative slope could be explained by the Clausius-Clapeyron equation, assuming that the entropy of phase V is larger than that of phase I or III for the disordered structure of phase V. The molar volume of phase V, despite being a high-temperature phase, is smaller than that of phase III at the same pressure from powder x-ray diffraction measurement; therefore, the thermal expansion would be small compared to the volume change at the phase transition from phase III to V.

Yamawaki, Hiroshi; Fujihisa, Hiroshi; Gotoh, Yoshito; Nakano, Satoshi

2015-01-01

366

Compliance of postoperative instructions following the surgical extraction of impacted lower third molars: A randomized clinical trial.  

PubMed

Objectives: The understanding and adherence to postoperative care instructions are factors that influence the recuperation process after any surgical procedure. The aim of this study was to determine the percentage of patients who strictly follow the postoperative instructions after the extraction of an impacted lower third molar in relation to sociocultural level, preoperative anxiety scores and how postoperative information is provided to the patient. Study Design: Patients were randomly assigned to one of three different test groups according to how the postoperative instructions were presented: verbal, written and a group that received additional information. Before surgery, patients were required to complete the Corah Dental Anxiety Scale and personal information (age, gender and educational level) was also collected. P <0.05 was considered significant. Patients were surveyed a week after surgery regarding their adherence to postoperative instructions. Results: 84 patients (45 women and 39 men with an average of 28.23 ± 7.41 years) completed the study. There were no statistically significant differences regarding adherence of postoperative care instructions depending on the manner of instruction presentation, preoperative anxiety level and sociocultural level (p> 0.05). Quitting smoking or drinking of alcoholic/carbonated beverages were the main influential factors for the lack of adherence to postoperative care instructions during the week after surgery. Conclusions: Presentation of postoperative instructions, preoperative anxiety scores and sociocultural level do not appear to be key factors that promote the adherence to postoperative instructions. PMID:25475774

Alvira-González, J; Gay-Escoda, C

2014-12-01

367

Molar absorptivities of 2,4-D, cymoxanil, fenpropidin, isoproturon and pyrimethanil in aqueous solution in the near-UV  

NASA Astrophysics Data System (ADS)

The absorption spectra of five pesticides, namely 2,4-dichloro-phenoxy acetic acid (2,4-D), cymoxanil, fenpropidin, isoproturon and pyrimethanil, have been measured in aqueous solution using a set-up consisting of two parallel absorption cells coupled to a CCD detector. The absolute values of their molar absorptivity coefficients ? were determined in the wavelength-range 240-344 nm with a deuterium-lamp at room temperature (298 ± 2 K). Using the Beer-Lambert law, values of ? were also determined at 253.7 nm with a Hg-Lamp: ? = 145 ± 14 for 2,4-D, ? = 7940 ± 920 for cymoxanil, ? = 196 ± 14 for fenpropidin, ? = 7330 ± 880 for isoproturon, ? = 13200 ± 1400 for pyrimethanil (in units of M -1 cm -1). The quoted errors correspond to 2 ? obtained from the least square fit analysis and the estimated systematic error of 5% due to the uncertainties in aqueous concentrations. For all the studied compounds, the absorbances measured were lower than 2.3 and did not exhibit any deviation from the Beer-Lambert's law. Our experimental data are discussed and compared to UV spectra of similar molecules when such data were available in the literature. Based on their UV spectra and the calculated fractions of these pesticides in the aqueous phase, their direct photolysis under sunlight environment could occur, except may be for fenpropidin, either in water surfaces or in aqueous droplets contained in the atmospheric clouds.

Feigenbrugel, Valérie; Le Calvé, Stéphane; Mirabel, Philippe

2006-01-01

368

Aurothiomalate as preventive and chain-breaking antioxidant in radical degradation of high-molar-mass hyaluronan.  

PubMed

The potential anti- or pro-oxidative effects of a disease-modifying antirheumatic drug, aurothiomalate, to protect high-molar-mass hyaluronan against radical degradation were investigated along with L-glutathione - tested in similar functions. Hyaluronan degradation was induced by the oxidative system Cu(II) plus ascorbate known as the Weissberger's oxidative system. The time- and dose-dependent changes of the dynamic viscosity of the hyaluronan solutions were studied by the method of rotational viscometry. Additionally, the antioxidative activity of aurothiomalate expressed as a radical-scavenging capacity based on a decolorization 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay was inspected. At the higher concentrations tested, L-glutathione showed excellent scavenging of (.) OH and peroxyl-type radicals, however, at the lowest concentration applied, its pro-oxidative effect was revealed. The effects of aurothiomalate on hyaluronan degradation were similar to that of L-glutathione, however, at the lowest concentration tested, no significant pro-oxidant effect was observed. PMID:21766448

Valachová, Katarína; Vargová, Andrea; Rapta, Peter; Hrabárová, Eva; Dráfi, František; Bauerová, Katarína; Juránek, Ivo; Soltés, Ladislav

2011-07-01

369

A molecular dynamics study of ambient and high pressure phases of silica: Structure and enthalpy variation with molar volume  

NASA Astrophysics Data System (ADS)

Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, ?-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume—for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase.

Rajappa, Chitra; Sringeri, S. Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J.

2014-06-01

370

Evolutionary Patterns in the Dentition of Duplicidentata (Mammalia) and a Novel Trend in the Molarization of Premolars  

PubMed Central

Background The cusp homology of Lagomorpha has long been problematic largely because their teeth are highly derived relative to their more typically tribosphenic ancestors. Within this context, the lagomorph central cusp has been particularly difficult to homologize with other tribosphenic cusps; authors have previously considered it the paracone, protocone, metacone, amphicone, or an entirely new cusp. Methodology/Principal Findings Here we present newly described fossil duplicidentates (Lagomorpha and Mimotonidae) in the context of a well-constrained phylogeny to establish a nomenclatural system for cusps based on the tribosphenic pattern. We show that the central cusp of lagomorphs is homologous with the metaconule of other mammals. We also show that the buccal acquisition of a second cusp on the premolars (molarization) within duplicidentates is atypical with respect to other mammalian lineages; within the earliest lagomorphs, a second buccal cusp is added mesially to an isolated buccal cusp. Conclusions/Significance The distal shift of the ‘ancestral’ paracone within early duplicidentates amounts to the changing of a paracone into a metacone in these lineages. For this reason, we support a strictly topological approach to cusp names, and suggest a discontinuity in nomenclature to capture the complexity of the interplay between evolutionary history and the developmental process that have produced cusp patterns in duplicidentates. PMID:20877465

Kraatz, Brian P.; Meng, Jin; Weksler, Marcelo; Li, Chuankui

2010-01-01

371

A molecular dynamics study of ambient and high pressure phases of silica: structure and enthalpy variation with molar volume.  

PubMed

Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, ?-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume-for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase. PMID:24985659

Rajappa, Chitra; Sringeri, S Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J

2014-06-28

372

Experimental and numerical determination of initial tooth mobility and material properties of the periodontal ligament in rat molar specimens.  

PubMed

The mechanical parameters of the periodontal ligament (PDL) in rat specimens were investigated in a combined experimental and numerical approach. Tooth mobility of the rat mandibular first molar was measured in vitro using a high precision experimental set-up. Finite element models (FEM) were developed, based on histological sections of the measured specimens, to simulate tooth mobility numerically under the same force systems as used in the experiment. Force/deflection curves from the measurements showed a significant non-linear behaviour of elastic stiffness of the PDL. A bilinear material parameter set was assumed to simulate tooth deflections. The numerical force/deflection curves were fitted to the experimental curves by repeatedly calculating theoretical tooth deflections and varying the parameters describing the non-linearity. Mean values of E1 = 0.15 MPa, E2 = 0.60 MPa and an ultimate strain of epsilon12 = 6.3 per cent were derived for the elastic behaviour of the rat PDL. Comparing fresh specimens and those frozen in a 0.9 per cent saline solution, differences between the measurements were significant. Using the agent, Periston, for freezing significantly reduced the deviation. The results indicated that strains in the PDL with a maximum of 14 per cent at the furcation were 10(4) times higher than strains in the bone, while the variability of stress values in both PDL and bone was not significant. PMID:14700262

Kawarizadeh, A; Bourauel, C; Jäger, A

2003-12-01

373

Primero Segundo Tercero Cuarto Diagrama de Dependencias Entre Asignaturas  

E-print Network

Informáticos I NC = Fundamentos de Neurocomputación (OP) TACC2 = Temas Avanzados en Ciencia de la Computación Artificial RC1 = Redes de Comunicaciones I AA = Análisis de Algoritmos (OP) CC1 = Computación Científica I del Conocimiento RC2 = Redes de Comunicaciones II TAII2 = Temas Avanzados en Ingeniería Informática I

Shafti, Leila

374

Standard partial molar volumes of some aqueous alkanolamines and alkoxyamines at temperatures up to 325 degrees C: functional group additivity in polar organic solutes under hydrothermal conditions.  

PubMed

Apparent molar volumes of dilute aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), N,N-dimethylethanolamine (DMEA), ethylethanolamine (EAE), 2-diethylethanolamine (2-DEEA), and 3-methoxypropylamine (3-MPA) and their salts were measured at temperatures from 150 to 325 degrees C and pressures as high as 15 MPa. The results were corrected for the ionization and used to obtain the standard partial molar volumes, Vo2. A three-parameter equation of state was used to describe the temperature and pressure dependence of the standard partial molar volumes. The fitting parameters were successfully divided into functional group contributions at all temperatures to obtain the standard partial molar volume contributions. Including literature results for alcohols, carboxylic acids, and hydroxycarboxylic acids yielded the standard partial molar volume contributions of the functional groups >CH-, >CH2, -CH3, -OH, -COOH, -O-, -->N, >NH, -NH2, -COO-Na+, -NH3+Cl-, >NH2+Cl-, and -->NH+Cl- over the range (150 degrees C molar volume of aqueous organic solutes composed of these groups at temperatures up to approximately 310 degrees C and pressures of 10-20 MPa to within a precision of +/-5 cm3 x mol(-1). The model could not be extended to higher temperatures because of uncertainties caused by thermal decomposition. At temperatures above approximately 250 degrees C, the order of the group contributions to Vo2 changes from that observed at 25 degrees C, to become increasingly consistent with the polarity of each functional group. The effect of the dipole moment of each molecule on the contribution to Vo2 from long-range solvent polarization was calculated from the multipole expansion of the Born equation using dipole moments estimated from restricted Hartree-Fock calculations with Gaussian 03 (Gaussian, Inc., Wallingford, CT) and the Onsager reaction-field approximation for solvent effects. Below 325 degrees C, the dipole contribution was found to be less than 2 cm3 x mol(-1) for all the solute molecules studied. At higher temperatures and pressures near steam saturation, the effect is much larger and may explain anomalies in functional group additivity observed in small, very polar solutes. PMID:18412415

Bulemela, E; Tremaine, Peter R

2008-05-01

375

Morphometric analysis of molars in a Middle Pleistocene population shows a mosaic of 'modern' and Neanderthal features.  

PubMed

Previous studies of upper first molar (M1) crown shape have shown significant differences between Homo sapiens and Homo neanderthalensis that were already present in the European Middle Pleistocene populations, including the large dental sample from Atapuerca-Sima de los Huesos (SH). Analysis of other M1 features such as the total crown base area, cusp proportions, cusp angles and occlusal polygon have confirmed the differences between both lineages, becoming a useful tool for the taxonomic assignment of isolated teeth from Late Pleistocene sites. However, until now the pattern of expression of these variables has not been known for the SH sample. This fossil sample, the largest collection from the European Middle Pleistocene, is generally interpreted as being from the direct ancestors of Neanderthals, and thus is a reference sample for assessing the origin of the Neanderthal morphologies. Surprisingly, our study reveals that SH M(1) s present a unique mosaic of H. neanderthalensis and H. sapiens features. Regarding the cusp angles and the relative occlusal polygon area, SH matches the H. neanderthalensis pattern. However, regarding the total crown base area and relative cusps size, SH M(1) s are similar to H. sapiens, with a small crown area, a strong hypocone reduction and a protocone enlargement, although the protocone expansion in SH is significantly larger than in any other group studied. The SH dental sample calls into question the uniqueness of some so-called modern traits. Our study also sounds a note of caution on the use of M(1) occlusal morphology for the alpha taxonomy of isolated M(1) s. PMID:23914934

Martinón-Torres, María; Sp?vá?ková, Petra; Gracia-Téllez, Ana; Martínez, Ignacio; Bruner, Emiliano; Arsuaga, Juan Luis; Bermúdez de Castro, José María

2013-10-01

376

Characterization of dental pulp stem cells from impacted third molars cultured in low serum-containing medium.  

PubMed

We isolated and expanded stem cells from dental pulp from extracted third molars using an innovative culture method consisting of low serum-containing medium supplemented with epidermal growth factor and platelet-derived growth factor BB. We evaluated the differentiation potential of these cells when they were growing either adherently or as micromass/spheroid cultures in various media. Undifferentiated and differentiated cells were analyzed by flow cytometry, immunocytochemistry and immunoblotting. The flow cytometry results showed that the dental pulp stem cells (DPSCs) were positive for mesenchymal stromal cell markers, but negative for hematopoietic markers. Immunocytochemical and/or immunoblotting analyses revealed the expression of numerous stem cell markers, including nanog, Sox2, nestin, Musashi-1 and nucleostemin, whereas they were negative for markers associated with differentiated neural, vascular and hepatic cells. Surprisingly, the cells were only slightly positive for ?-smooth muscle actin, and a heterogeneous expression of CD146 was observed. When cultured in osteogenic media, they expressed osteonectin, osteopontin and procollagen I, and in micromass cultures, they produced collagen I. DPSCs cultured in TGF-?1/3-supplemented media produced extracellular matrix typical of cartilaginous tissue. The addition of vascular endothelial growth factor to serum-free media resulted in the expression of endothelial markers. Interestingly, when cultured in neurogenic media, DPSCs exhibited de novo or upregulated markers of undifferentiated and differentiated neural cells. Collectively, our data show that DPSCs are self-renewing and able to express markers of bone, cartilage, vascular and neural tissues, suggesting their multipotential capacity. Their easy accessibility makes these cells a suitable source of somatic stem cells for tissue engineering. PMID:21071916

Karbanová, Jana; Soukup, Tomáš; Suchánek, Jakub; Pytlík, Robert; Corbeil, Denis; Mokrý, Jaroslav

2011-01-01

377

Molar absorptivities of 2,4-D, cymoxanil, fenpropidin, isoproturon and pyrimethanil in aqueous solution in the near-UV.  

PubMed

The absorption spectra of five pesticides, namely 2,4-dichloro-phenoxy acetic acid (2,4-D), cymoxanil, fenpropidin, isoproturon and pyrimethanil, have been measured in aqueous solution using a set-up consisting of two parallel absorption cells coupled to a CCD detector. The absolute values of their molar absorptivity coefficients epsilon were determined in the wavelength-range 240-344 nm with a deuterium-lamp at room temperature (298+/-2 K). Using the Beer-Lambert law, values of epsilon were also determined at 253.7 nm with a Hg-Lamp: epsilon = 145+/-14 for 2,4-D, epsilon = 7940+/-920 for cymoxanil, epsilon = 196+/-14 for fenpropidin, epsilon = 7330+/-880 for isoproturon, epsilon = 13200+/-1400 for pyrimethanil (in units of M(-1) cm(-1)). The quoted errors correspond to 2 sigma obtained from the least square fit analysis and the estimated systematic error of 5% due to the uncertainties in aqueous concentrations. For all the studied compounds, the absorbances measured were lower than 2.3 and did not exhibit any deviation from the Beer-Lambert's law. Our experimental data are discussed and compared to UV spectra of similar molecules when such data were available in the literature. Based on their UV spectra and the calculated fractions of these pesticides in the aqueous phase, their direct photolysis under sunlight environment could occur, except may be for fenpropidin, either in water surfaces or in aqueous droplets contained in the atmospheric clouds. PMID:16256424

Feigenbrugel, Valérie; Le Calvé, Stéphane; Mirabel, Philippe

2006-01-01

378

Evaluation of Micromovements and Stresses around Single Wide-Diameter and Double Implants for Replacing Mandibular Molar: A Three-Dimensional FEA  

PubMed Central

Purpose. The purpose of this finite element study was to compare stresses, strains, and displacements of double versus single implant, in immediate loading for replacing mandibular molar. Materials and Methods. Two 3D FEM models were made to simulate implant designs. The first model used 6?mm wide-diameter implant to support a single molar crown. The second model used 3.75-3.75 double implant design. Each model was analyzed with a single force magnitude of 70?N in oblique axis in three locations. Results. This FEM study suggested that micromotion can be well controlled by both double implants and 6?mm single wide-diameter implant. The Von Mises stress for double implant had 31%–43% stress reduction compared to the 6?mm implant. Conclusion. Within the limitations of the paper, when the mesiodistal space for artificial tooth is more than 12.5?mm, under immediate loading, the double implant support should be considered. PMID:22461992

Desai, Shrikar R.; Karthikeyan, I.; Singh, Rika

2012-01-01

379

Temperature Dependence of Densities and Excess Molar Volumes of the Ternary Mixture (1-Butanol + Chloroform + Benzene) and its Binary Constituents (1-Butanol + Chloroform and 1-Butanol + Benzene)  

NASA Astrophysics Data System (ADS)

Densities ? of the 1-butanol + chloroform + benzene ternary mixture and the 1-butanol + chloroform and 1-butanol + benzene binaries have been measured at six temperatures (288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure, using an oscillating U-tube densimeter. From these densities, excess molar volumes ( V E) were calculated and fitted to the Redlich Kister equation for all binary mixtures and to the Nagata and Tamura equation for the ternary system. The Radojkovi? et al. equation has been used to predict excess molar volumes of the ternary mixtures. Also, V E data of the binary systems were correlated by the van der Waals (vdW1) and Twu Coon Bluck Tilton (TCBT) mixing rules coupled with the Peng Robinson Stryjek Vera (PRSV) equation of state. The prediction and correlation of V E data for the ternary system were performed by the same models.

Smiljani?, Jelena D.; Kijev?anin, Mirjana Lj.; Djordjevi?, Bojan D.; Grozdani?, Dušan K.; Šerbanovi?, Slobodan P.

2008-04-01

380

A beta-Diketonato Ruthenium(II) Complex with High Molar Extinction Coefficient for Panchromatic Sensitization of Nanocrystalline TiO2 Film  

Microsoft Academic Search

A dye-sensitized solar cell (DSC) was fabricated using a new beta-diketonato ruthenium(II) sensitizer with a broad absorption range and a high molar extinction coefficient of 11.3× 103 M-1 cm-1 at 584 nm. Efficient sensitization of nanocrystalline TiO2 film was observed across the whole visible range and into the near-IR region as far as 1000 nm. The incident photon-to-current conversion efficiency

Shang Gao; Ashraful Islam; Youhei Numata; Liyuan Han

2010-01-01

381

An In vitro Comparison of Furcal Perforation Repaired with Pro-root MTA and New Endodontic Cement in Primary Molar Teeth- A Microleakage Study  

PubMed Central

Statement of Problem: One of the most challenging procedural accidents during pulpotomy of primary molars is furcal perforation. To prevent bacterial invasion, the perforation site should be sealed as soon as possible. Purpose: The aim of the current study is to investigate the ability of the pro-root MTA and new endodontic cement (NEC) in repairing the furcation perforations of primary molar teeth. Materials and Method: In this in vitro study, 42 extracted primary molars were selected. Their roots were sectioned horizontally and standard access cavity was prepared. The orifices and the root apices were sealed with two layers of resin composite.The samples were randomly assigned into 2 groups. 6 teeth were considered as the positive and the negative controls. In the experimental groups; perforation was made. In group 1 and 2, perforation site received pro-root MTA and NEC respectively. The teeth were covered by two layers of nail polish except for the external surface of the perforation site. The negative control group received no repairing material. All teeth were mounted and sterilized for 24 hours. Lower chambers were filled with sterilized Muller Hinton broth. Bacterial suspension of Enterococcus faecalis in 0.5 McFarland was prepared. The repaired site was then exposed to the bacterial suspension of Enterococcus faecalis every 3 days. All samples were inserted in an incubator at 37oC and 100% humidity. The turbidity of the samples was detected for a period of 30 days. Data were analyzed by Chi- square test. Results: 44% of samples in Pro- root group, 50% of the samples in the NEC group showed contaminations during 30 days. There was no significant difference between these two groups (p= 0.799). Conclusion: With limitations of this study, Pro- root MTA and NEC showed similar capability in sealing the furcal perforations of the primary molars. PMID:24738087

Haghgoo, R.; Niyakan, M.; Nazari Moghaddam, K.; Asgary, S.; Mostafaloo, N.

2014-01-01

382

Influence of Fe\\/Ba molar ratio on the characteristics of Ba-hexaferrite particles prepared by sol–gel combustion method  

Microsoft Academic Search

Nano-crystalline particles of barium hexaferrite (BaFe12O19) have been prepared by a sol–gel combustion technique using nitrate–citrate gels prepared from metal nitrates and citric acid solutions under various Fe\\/Ba molar ratios of 10, 11 and 12. The thermal decomposition process of the nitrate–citrate gels and as-burnt powders was investigated by XRD and DTA\\/TGA techniques. The results revealed that the nitrate citrate

A. Mali; A. Ataie

2005-01-01

383

Diagnostic accuracy of cone-beam CT compared with panoramic images in predicting retromolar canal during extraction of impacted mandibular third molars  

PubMed Central

Objectives: The clinical significance of the existence of a retromolar canal and of its neurovascular content is not yet clear.The aim of the present study was to assess the visibility, diameter and course of the mandibular retromolarcanal (MRC) using cone beam computed tomography (CBCT) scan -had been taken for pre-operative radiographic evaluation of impacted mandibular third molars- compared to panoramic radiographs. Study Design: Subjects eligible for study enrollment were those who underwent preoperative CBCT scan for the extraction of impactedmandibular third molars were determined to be extremely close to the mandibular canal on panoramic radiographs. Radiographs were screened for the presence and course of retromolar canals, and linear measurements. Results: 947hemimandibles in 632 patients were examined.A total of 253 MRCs (144 left, 109 right) were detected with CBCT images (26.7%). Only 29 of these canals were also seen on the corresponding panoramic radiographs. Most MRCs had a vertical course (type VI, 28.46%), followed by slightly curved (type I, 26.09%). The visibility of the MRC on the OPGs, according to the increase in the diameter, was not statistically significant for both sides (p>.05).Statistically difference were found for the width at the point of origin from the mandibular canal (p: .037), the mean distance from the MRC to the second molar (p: .042) and height of MRC when compared the gender. Conclusions: The findings suggest that the MRC isn’t a rare anatomical structure. This study therefore clearly establishes the incidence and importance of the MRC. The detection of the presence of the MRC using CBCT may be crucial for extraction of mandibular third molars. Key words:Accessory innervation, cone beam computed tomography, mandibular anatomy, panoramic radiographs, retromolar canal, retromolar foramen. PMID:25475767

Sisman, Y?ld?ray; Payveren-Ar?kan, Mehtap; Sahman, Halil

2015-01-01

384

Human dental age estimation using third molar developmental stages: does a Bayesian approach outperform regression models to discriminate between juveniles and adults?  

Microsoft Academic Search

Dental age estimation methods based on the radiologically detected third molar developmental stages are implemented in forensic\\u000a age assessments to discriminate between juveniles and adults considering the judgment of young unaccompanied asylum seekers.\\u000a Accurate and unbiased age estimates combined with appropriate quantified uncertainties are the required properties for accurate\\u000a forensic reporting. In this study, a subset of 910 individuals uniformly

P. W. Thevissen; S. Fieuws; G. Willems

2010-01-01

385

Type I canal configuration in a single rooted maxillary first molar diagnosed with an aid of cone beam computed tomographic technique: A rare case report  

PubMed Central

Anatomic variations in maxillary molars are frequent. These deviations are also one of the major cause for endodontic treatment failure owing to inadequate cleaning, shaping and sealing of root canal system. Diagnosis of such aberrations using newer imaging techniques like cone beam computed tomography is firmly advocated. The present paper highlights the root canal treatment of a rare case of type I canal morphology diagnosed with an aid of cone beam computed tomographic technique. PMID:23956547

Chhabra, Naveen; Singbal, Kiran P; Chhabra, Tamanna Marwah

2013-01-01

386

The isolation of chondroitin 4-[ 35 S]sulphate from the molar teeth of young rats receiving sodium[ 35 S]sulphate  

Microsoft Academic Search

Six-weeks-old Wistar rats were injected intraperitoneally with sodium [35S]sulphate. The animals were sacrificed after 1 h and the molar teeth were extracted. The pulp and dentine were isolated by differential flotation and examined for glycosaminoglycans following decalcification and proteolysis. Examination of the product by cellulose acetate electrophoresis revealed the presence of a single metachromatic component which was radioactive. Chemical analysis,

G. Embery

1974-01-01

387

Development and cell fate in interspecific ( mus musculus\\/mus caroli) intraocular transplants of mouse molar tooth-germ tissues detected by in situ hybridization  

Microsoft Academic Search

Mandibular first molar tooth germs were dissected from Mus musculus (CD1) and Mus caroli (age range: 14-day embryo to 1-day postnatal). Most of the tooth germs were separated enzymically into epithelial and mesenchymal components. Interspecific tissue recombinations and intact M. caroli tooth germs were grown in the anterior chamber of the eye of adult CD1 mice for 2–4 weeks. Recombinations

M. J. Lubbock; V. T. Harrison; A. G. S. Lumsden; R. M. Palmer

1996-01-01

388

Diagnostic accuracy of cone-beam CT compared with panoramic images in predicting retromolar canal during extraction of impacted mandibular third molars.  

PubMed

Objectives: The clinical significance of the existence of a retromolar canal and of its neurovascular content is not yet clear.The aim of the present study was to assess the visibility, diameter and course of the mandibular retromolarcanal (MRC) using cone beam computed tomography (CBCT) scan -had been taken for pre-operative radiographic evaluation of impacted mandibular third molars- compared to panoramic radiographs. Study Design: Subjects eligible for study enrollment were those who underwent preoperative CBCT scan for the extraction of impactedmandibular third molars were determined to be extremely close to the mandibular canal on panoramic radiographs. Radiographs were screened for the presence and course of retromolar canals, and linear measurements. Results: 947hemimandibles in 632 patients were examined.A total of 253 MRCs (144 left, 109 right) were detected with CBCT images (26.7%). Only 29 of these canals were also seen on the corresponding panoramic radiographs. Most MRCs had a vertical course (type VI, 28.46%), followed by slightly curved (type I, 26.09%). The visibility of the MRC on the OPGs, according to the increase in the diameter, was not statistically significant for both sides (p >.05).Statistically difference were found for the width at the point of origin from the mandibular canal (p: .037), the mean distance from the MRC to the second molar (p: .042) and height of MRC when compared the gender. Conclusions: The findings suggest that the MRC isn't a rare anatomical structure. This study therefore clearly establishes the incidence and importance of the MRC. The detection of the presence of the MRC using CBCT may be crucial for extraction of mandibular third molars. PMID:25475767

Sisman, S Sisman; Ercan-Sekerci, A; Payveren-Arikan, M; Sahman, H

2014-12-01

389

2,3,7,8-Tetrachlorodibenzo-p-dioxin specifically reduces mRNA for the mineralization-related dentin sialophosphoprotein in cultured mouse embryonic molar teeth  

SciTech Connect

Previous studies show that the most toxic dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), interferes with mineralization of the dental matrices in developing mouse and rat teeth. Culture of mouse embryonic molar teeth with TCDD leads to the failure of enamel to be deposited and dentin to undergo mineralization. Lactationally exposed rats show defectively matured enamel and retardation of dentin mineralization. To see if the impaired mineralization is associated with changes in the expression of dentin sialophosphoprotein (Dspp), Bono1 and/or matrix metalloproteinase-20 (MMP-20), thought to be involved in mineralization of the dental hard tissues, we cultured mouse (NMRI) E18 mandibular molars for 3, 5 or 7 days and exposed them to 1 {mu}M TCDD after 2 days of culture. As detected by in situ hybridization of tissue sections, localization and intensity of Bono1 and MMP-20 expression showed no definite difference between the control and exposed tooth explants, suggesting that TCDD does not affect their expression. On the contrary, TCDD reduced or prevented the expression of Dspp in secretory odontoblasts and decreased it in presecretory ameloblasts. The results suggest that the retardation of dentin mineralization by TCDD in mouse molar teeth involves specific interference with Dspp expression.

Kiukkonen, Anu [Department of Pediatric and Preventive Dentistry, Institute of Dentistry, University of Helsinki, Helsinki (Finland) and Department of Oral Pathology, Institute of Dentistry, University of Helsinki, Helsinki (Finland)]. E-mail: Anu.Kiukkonen@helsinki.fi; Sahlberg, Carin [Department of Pediatric and Preventive Dentistry, Institute of Dentistry, University of Helsinki, Helsinki (Finland); Lukinmaa, Pirjo-Liisa [Department of Oral Pathology, Institute of Dentistry, University of Helsinki, Helsinki (Finland); Department of Pathology, Helsinki University Central Hospital, Helsinki (Finland); Alaluusua, Satu [Department of Pediatric and Preventive Dentistry, Institute of Dentistry, University of Helsinki, Helsinki (Finland); Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital, Helsinki (Finland); Peltonen, Eija [Department of Pediatric and Preventive Dentistry, Institute of Dentistry, University of Helsinki, Helsinki (Finland); Department of Oral Pathology, Institute of Dentistry, University of Helsinki, Helsinki (Finland); Partanen, Anna-Maija [Department of Pediatric and Preventive Dentistry, Institute of Dentistry, University of Helsinki, Helsinki (Finland)

2006-11-01

390

Lattice potential energy and standard molar enthalpy in the formation of 1—dodecylamine hydrobromide (1-C12H25NH3·Br)(s)  

NASA Astrophysics Data System (ADS)

This paper reports that 1-dodecylamine hydrobromide (1-C12H25NH3·Br)(s) has been synthesized using the liquid phase reaction method. The lattice potential energy of the compound 1-C12H25NH3·Br and the ionic volume and radius of the 1-C12H25NH3+ cation are obtained from the crystallographic data and other auxiliary thermodynamic data. The constant-volume energy of combustion of 1-C12H25NH3·Br(s) is measured to be ?cUmo(1-C12H25NH3·Br, s) = -(7369.03±3.28) kJ·mol-1 by means of an RBC-II precision rotating-bomb combustion calorimeter at T = (298.15±0.001) K. The standard molar enthalpy of combustion of the compound is derived to be ?cHmo(1-C12H25NH3·Br, s) = -(7384.52±3.28) kJ·mol-1 from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound is calculated to be ?fHmo(1-C12H25NH3·Br, s)=-(1317.86±3.67) kJ·mol-1 from the standard molar enthalpy of combustion of the title compound and other auxiliary thermodynamic quantities through a thermochemical cycle.

Liu, Yu-Pu; Di, You-Ying; Dan, Wen-Yan; He, Dong-Hua; Kong, Yu-Xia; Yang, Wei-Wei

2011-02-01

391

A Comparative Clinical Evaluation of the Effect of Preoperative and Postoperative Antimicrobial Therapy on Postoperative Sequelae after Impacted Mandibular Third Molar Extraction  

PubMed Central

ABSTRACT Objectives To compare the effect of preoperative and postoperative antibiotics therapy on postoperative sequelae after impacted mandibular third molar extractions. Material and Methods This was a prospective study conducted at Department of Oral and Maxillofacial Surgery of the Lagos University Teaching Hospitalon consecutive patients with impacted third molar extractions for a 12 month period. Group I (n = 31) had administration of 1 gram of oral metronidazole and 1 gram of amoxicillin capsules 30 minutes preoperative and Group II (n = 31) had 500 milligrams of amoxicillin capsule 8 hourly and 400 milligrams of metronidazole tablets administered post operatively for 5 days. Pain, facial swelling and mouth opening assessment were done postoperatively and on days 1, 3 and 7. Results The general pattern of postoperative pain, regardless of antimicrobial use revealed that pain increased from day 1 to day 3 postoperatively and began to decrease in intensity subsequently up to the seventh day. There was however a statistically significant difference (P = 0.0001) between the two groups on the 7th postoperative day with the subjects in Group I showing lower pain intensity. The mean difference of the facial width on days 1 and 3 was significant (P = 0.04 and P = 0.0001 respectively) with subjects in Group II having a reduced facial width compared to those in Group I. Conclusions This study suggested that the administration of preoperative or postoperative antibiotics showed no marked differences in the degree of postoperative sequaele that occur after impacted mandibular third molar extractions. PMID:25089174

Gbotolorun, Olalekan Micah; Ibikunle, Adebayo Aremu; Emeka, Christian Ibezi; Arotiba, Godwin Toyin; Akinwande, Jelili Adisa

2014-01-01

392

Nutritional status and phytate:zinc and phytate x calcium:zinc dietary molar ratios of lacto-ovo vegetarian Trappist monks: 10 years later.  

PubMed

A nutrition assessment of 16 members of a community of lacto-ovo vegetarian Trappist monks was conducted in 1977. Plasma zinc was found to be low-normal, which was attributed primarily to high intakes of phytate-containing foods. Individual and group counseling were instituted over a 10-year period in an attempt to emphasize the importance of wise food selection within the constraints of lacto-ovo vegetarianism. In 1987, a more comprehensive nutrition assessment of 21 members of the same community was performed. Food composites were analyzed, and 3-day instead of 24-hour dietary records were kept. Intakes of phytate-containing foods had decreased from 4,569 to 972 mg/day; intake of dietary zinc had increased from 7.4 to 9.7 mg/day; and the phytate:zinc molar ratio had decreased from 67 to 14 for the years 1977 and 1987, respectively. An analyzed phytate:zinc molar ratio of 9.8 and an analyzed phytate x calcium:zinc molar ratio of 0.3 were representative of the 1987 community. Both were within normal ranges. Plasma zinc had risen to upper-normal levels. The 1987 nutrition assessment showed that it is possible to be adequately nourished with a lacto-ovo vegetarian diet provided one has proper knowledge of the phytate-containing foods and the methods for compensating with foods of greater mineral density (primarily zinc). PMID:3192878

Harland, B F; Smith, S A; Howard, M P; Ellis, R; Smith, J C

1988-12-01

393

Biodegradable in situ gelling delivery systems containing pilocarpine as new antiglaucoma formulations: effect of a mercaptoacetic acid/N-isopropylacrylamide molar ratio  

PubMed Central

Ocular drug delivery is one of the most commonly used treatment modalities in the management of glaucoma. We have recently proposed the use of gelatin and poly(N-isopropylacrylamide) (PNIPAAm) graft copolymers as biodegradable in situ forming delivery systems for the intracameral administration of antiglaucoma medications. In this study, we further investigated the influence of carrier characteristics on drug delivery performance. The carboxyl-terminated PNIPAAm samples with different molecular weights were synthesized by varying the molar ratio of mercaptoacetic acid (MAA)/N-isopropylacrylamide (NIPAAm) from 0.05 to 1.25, and were determined by end-group titration. The preparation of gelatin-g-PNIPAAm (GN) copolymers from these thermoresponsive polymers was achieved using carbodiimide chemistry. Our results showed that the carboxylic end-capped PNIPAAm of high molecular weight may lead to the lower thermal phase transition temperature and slower degradation rate of GN vehicles than its low molecular weight counterparts. With a decreasing MAA/NIPAAm molar ratio, the drug encapsulation efficiency of copolymers was increased due to fast temperature-triggered capture of pilocarpine nitrate. The degradation of the gelatin network could greatly affect the drug release profiles. All of the GN copolymeric carriers demonstrated good corneal endothelial cell and tissue compatibility. It is concluded that different types of GN-based delivery systems exhibit noticeably distinct intraocular pressure-lowering effect and miosis action, thereby reflecting the potential value of a MAA/NIPAAm molar ratio in the development of new antiglaucoma formulations. PMID:24187486

Lai, Jui-Yang

2013-01-01

394

A macroscopic model that connects the molar excess entropy of a supercooled liquid near its glass transition temperature to its viscosity  

NASA Astrophysics Data System (ADS)

For a deeply supercooled liquid near its glass transition temperature, we suggest a possible way to connect the temperature dependence of its molar excess entropy to that of its viscosity by constructing a macroscopic model, where the deeply supercooled liquid is assumed to be a mixture of solid-like and liquid-like micro regions. In this model, we assume that the mole fraction x of the liquid-like micro regions tends to zero as the temperature T of the liquid is decreased and extrapolated to a temperature T_g^*, which we assume to be below but close to the lowest glass transition temperature Tg attainable with the slowest possible cooling rate for the liquid. Without referring to any specific microscopic nature of the solid-like and liquid-like micro regions, we also assume that near Tg, the molar enthalpy of the solid-like micro regions is lower than that of the liquid-like micro regions. We then show that the temperature dependence of x is directly related to that of the molar excess entropy. Close to Tg, we assume that an activated motion of the solid-like micro regions controls the viscosity and that this activated motion is a collective motion involving practically all of the solid-like micro-regions so that the molar activation free energy ?ga for the activated motion is proportional to the mole fraction, 1 - x, of the solid-like micro regions. The temperature dependence of the viscosity is thus connected to that of the molar excess entropy se through the temperature dependence of the mole fraction x. As an example, we apply our model to a class of glass formers for which se at temperatures near Tg is well approximated by se ? 1 - TK/T with T_K < T_g \\cong T_g^* and find their viscosities to be well approximated by the Vogel-Fulcher-Tamman equation for temperatures very close to Tg. We also find that a parameter a appearing in the temperature dependence of x for a glass former in this class is a measure for its fragility. As this class includes both fragile and strong glass formers, our model applies to both fragile and strong glass formers. We estimate the values of three parameters in our model for three glass formers in this class, o-terphenyl, 3-bromopentane, and Pd40Ni40P20, which is the least fragile among these three. Finally, we also suggest a way to test our assumption about the solid-like and liquid-like micro regions by means of molecular dynamics simulations of model liquids.

Matsuoka, Hiroshi

2012-11-01

395

Potential Risk of Asymptomatic Osteomyelitis around Mandibular Third Molar Tooth for Aged People: A Computed Tomography and Histopathologic Study  

PubMed Central

The purpose of this study was to explore the relationship between bone mineral density and histopathological features of mandibular alveolar bone evaluated quantitatively by Hounsfield units [HU] and by histopathology in human subjects. Fifty-six mandibular molars were extracted in 50 patients. Computed tomography was obtained preoperatively, and a cortical bone biopsy was obtained on the extracted sites for histopathological evaluation. The mean cortical and cancellous bone radiodensity was 1846±118 HU and 926±436 HU, respectively. There was no correlation between age and cortical bone HU (r?=??0.004, P?=?0.976); however, the correlation between age and cancellous bone HU was significant (r?=?0.574, P<0.0000). Significant differences in the cancellous bone between young (0–30 years), middle (31–60 years) and old patient groups (61< years) were evident (P<0.05), whereas the cortical bone presented no significant differences. The histopathological evaluation showed that the young patient group had relatively few osteomyelitis, whereas the old patient group showed 100% focal sclerotic osteomyelitis regardless of the fact that the patients had no clinical symptoms. The mean osteocyte number/unit bone area was 170.7±82.2. Negative correlation between age and osteocyte number was significant (r?=??0.51, P<0.0001). Mean lacunae numbers/unit cortical bone area were 413.1±130 with non-significant negative correlation (r?=??0.257, P?=?0.056). The mean empty lacunae numbers/cortical bone were 242.5±145, with no correlation (r?=?0.081, P?=?0.559). The young patients had high osteocyte number, whereas the old patients showed reduction of the osteocytes in the cortical bone (P<0.05). Bone quality might correlate better to viable cell numbers, which influenced the osseous healing. It is suggested that the outermost layer of cortical bone may have lost its cellular activities over the years due to chronic infection, which may have provoked sclerotic changes in the cancellous bone around tooth. PMID:24040109

Miyamoto, Ikuya; Ishikawa, Ayataka; Morimoto, Yasuhiro; Takahashi, Tetsu

2013-01-01

396

The Molar Volume of FeO-MgO-Fe2O3-Cr2O3-Al2O3-TiO2 Spinels  

NASA Astrophysics Data System (ADS)

A new model of molar volume has been calibrated in the spinel supersystem (Mg,Fe2+)(Al,Cr,Fe3+)2O4 - (Mg,Fe2+)2TiO4. A total of 832 X-ray and neutron diffraction experiments performed on spinels at ambient and in situ high-P, T conditions (from the American Mineralogist Crystal Structure Database (Downs and Hall-Wallace, 2003) and other sources) were used to calibrate end-member equations of state and an excess volume model for this system. The effect on molar volume of cation ordering over the octahedral and tetrahedral sites is captured with linear dependence on Mg2+, Al3+, and Fe3+ site occupancy terms. We allowed standard state volumes and coefficients of thermal expansion of the end members to vary within their uncertainties during extraction of the mixing properties, in order to achieve the best fit. Published equations of states of the various spinel end members were analyzed to obtain optimal values of the bulk modulus and its pressure derivative, for each explicit end member. For any spinel composition in the supersystem, the model molar volume is obtained by adding excess volume and cation order-dependent terms to a linear combination of the five end member volumes, estimated at pressure and temperature using the high-T Vinet equation of state. The model has a total of 31 parameters and fits nearly all experiments to within 0.02 J/bar/mol, or better than 0.5% in volume. The model is compared to the current MELTS (Ghiorso and Sack, 1995; Ghiorso et al., 2002) spinel model with a demonstration of the impact of the model difference on the estimated spinel-garnet lherzolite transition pressure. Our primary motivation in this work is the development of a comprehensive spinel molar volume model for use in calibration of activity-composition models of garnet and pyroxene solid solutions. The thermodynamic models, along with a new silicate liquid equation of state, will be incorporated into the next generation MELTS model, xMELTS. The new solid solution models will include some minor components, including Ti4+ and Cr3+. Because most constraints on the activity of garnet and pyroxene at high-P are derived from experiments with coexisting spinel, we must be confident in the ability of our spinel model to realistically reproduce thermodynamic behavior over all applicable compositions. Additionally, producing a spinel molar volume model calibrated with recent in situ high-P, T diffraction data is crucial to our ability to accurately model the spinel-garnet transition in Earth's upper mantle. For example, we recently calibrated Cr-Al exchange equilibria for garnet and spinel. When this new calibration is used with the current MELTS model, a region of garnet-spinel coexistence in lherzolites is predicted with width in pressure comparable to experimental constraints. The transition occurs, however, at the unexpectedly low pressure of ~1.7 GPa. The improved model of spinel molar volume presented here, along with a new garnet molar volume model in the system FeO-MgO-CaO-Fe2O3-Cr2O3-Al2O3-TiO2-Na2O-SiO2 currently being calibrated, will enable coupled recalibration of the garnet and pyroxene models to match both the absolute pressure and width of this key transition in mantle lithology.

Hamecher, E. A.; Antoshechkina, P. M.; Ghiorso, M. S.; Asimow, P. D.

2011-12-01

397

Mineral Specific IR Molar Absorption Coefficients for Routine Water Determination in Olivine, SiO2 polymorphs and Garnet  

NASA Astrophysics Data System (ADS)

Conventionally applied Infrared (IR) calibrations [1, 2] for quantitative water analyses in solids are established on hydrous minerals and glasses with several wt% water. These calibrations are based on a negative correlation between the IR molar absorption coefficient (?) for water and the mean wavenumber of the corresponding OH pattern. The correlation reflects the dependence of the OH band position on the appropriate O- H...O distances and thereby the magnitude of the dipole momentum which is proportional to the band intensity. However, it has been observed that these calibrations can not be adopted to nominally anhydrous minerals (NAMs) [3].To study the potential dependence of ? on structure and chemistry in NAMs we synthesized olivine and SiO2 polymorphs with specific isolated hydroxyl point defects, e.g. quartz, coesite and stishovite with B3++H+=Si4+ and/or Al3++H+=Si4+ substitutions. Experiments were performed with water in excess in piston cylinder and multi-anvil presses. Single crystal IR spectra demonstrate that we successfully managed to seperate generally complex OH patterns as e.g. observed in natural quartz and synthetic coesite. We quantified sample water contents of both natural samples and our run products by applying proton-proton-scattering [4], confocal microRaman spectroscopy [5] and Secondary Ion mass spectrometry. Resulting water concentrations were used to calculate new mineral specific ?s. For olivine with the mean wavenumber of 3517 cm-1 we determined an ? value of 41,000±5,000 lmol-1H2Ocm-2. Quantification of olivine with the mean wavenumber of 3550 cm-1 in contrast resulted in an ? value of 47,000±1,000 lmol-1H2Ocm-2. Taking into account previous studies [6, 7] there is evidence to suggest a linear wavenumber dependent correlation for olivine, where ? increases with decreasing wavenumber. In case of the SiO2 system it turns out that the magnitude of ? within one structure type is independent of the liable OH point defect and therewith the wavenumber of the observed band position. Consequently, one single mean ? of 68,000±5,000 lmol-1H2Ocm-2 could be determined for a suite of quartz samples with varying OH point defects. In contrast, ? varies with the structure itself. For polymorphic coesite we calculated a different ? of 214,000±8,000 lmol-1H2O}cm-2, that is in good agreement with earlier established data [8]. Quantification data of stishovite resulted in an even higher value of ?=867,000±29,000 lmol-1H2Ocm-2, similar to that determined by [9]. First data on natural garnet give an ? value of 40,000±2,000 lmol-1H2Ocm-2, that confirms prior suggested values [10]. Our results demonstrate that not using mineral specific calibrations for quantitative water analyses in NAMs leads to overestimation of sample water concentrations, that are required for modelling the earth's deep water cycle. [1]Paterson, M. S. (1982), Bull. Min., 105, 20-29. [2]Libowitzky, E., Rossman, G. R. (1997), Am. Min., 82, 1111- 1115. [3]Rossman, G. R. (2006), Rev. Mineral., 62, 1-28. [4]Reichart et al. (2004), Science, 306, 1537-1540. [5]Thomas et al. (2006), Am. Min., 91, 467-470. [6]Bell et al. (2003), JGR, 108, (B2), 2105-2113. [7]Koch-Mueller et al. (2006), PCM, 33, 276-287. [8]Koch-Mueller et al. (2001), PCM, 28, 693-705. [9]Pawley et al. (1993), Science, 261, 1024-1026. [10]Maldener et al. (2003), PCM, 30, 337-344.

Thomas, S.; Koch-Mueller, M.; Reichart, P.; Rhede, D.; Thomas, R.

2007-12-01

398

Assessing Health-Related Quality of Life with Antimicrobial Photodynamic Therapy (APDT) and Low Level Laser Therapy (LLLT) after Third Molar Removal  

PubMed Central

Introduction: The purpose of this study was to evaluate the antimicrobial photodynamic therapy (APDT) and low level laser therapy (LLLT) on wound healing, pain intensity, swelling problems, halitosis and the postoperative usage of analgesics after surgical removal of lower third molars. Methods: One hundred and fifty patients, randomly divided into three groups were selected (50 per each group). The P1 group received the APDT after a third molar surgery, the P2 group received the LLLT and the C group (control group) was without any additional therapy after surgery. A photoactive substance was applied in the APDT study group before suturing. After 60 seconds the photosensitive substance was thoroughly washed with saline water and the laser light was applied in two intervals (30 seconds each). The irradiation power was 50 mW while the wavelength was 660 nm. The laser therapy in P2 group was performed before suturing and the laser light was applied also in two intervals (90 seconds each), the irradiation power was 90 mW while the wavelength was the same as in the first group – 660 nm. Postoperative follow-ups were scheduled on the third and the seventh day in patients who received laser therapy. Results: The results of the postoperative evaluation showed that there was a statistically significant difference in the postoperative wound healing, pain intensity, swelling problems, halitosis and analgesics intake between patients in all three groups (p<0.001). The patients that were subjected to APDT (P1) had the least postoperative problems. After the laser therapy (P1 and P2) wound healing was without any complications, opposite from the patients from the C group (p<0.001). Postoperative application of a laser therapy significantly reduced patient’s use of analgesics over the observed period of time (p<0.001). Conclusion: Both modalities of laser therapy significantly reduced postoperative problems after surgical removal of third lower molars with the best results in both laser groups.

Batinjan, Goran; Filipovi? Zore, Irina; Rupi?, Ivana; Bago Juri?, Ivona; Zore, Zvonimir; Gabri? Panduri?, Dragana

2013-01-01

399

Assessment of legal adult age of 18 by measurement of open apices of the third molars: Study on the Albanian sample.  

PubMed

The third molar tooth is one of the few anatomical structures in development available for estimating the age of individuals in the late adolescence. This study tests the accuracy of Cameriere's cut-off value of the third molar index (I3M) in assessing legal adult age of 18 years in an Albanian sample. For this purpose, a sample of orthopantomograms (OPTs) of 286 living subjects (152 female and 134 male) aged between 15 and 22 years was analyzed. Intra-rater and inter-raters agreement of I3M were 0.998 and 0.998, respectively and Cohen Kappa for intra-rater and inter-rater agreement in decision on adult or minor was 1.0 and 1.0, respectively. Age distribution gradually decreases as I3M increases in both males and females. The mean age of females is higher than that of males when I3M is between 0.04 and 0.08. Sensitivity test for males was 94.1%, with a 95% confidence interval (95% CI) 85.6-98.4%, and specificity was 90.9% (95%CI 81.3-96.6%). The proportion of correctly classified individuals was 92.5%, with a 95%CI of (86.7%, 96.4%). For females, the sensitivity test was 75.4%, with a 95%CI of (63.1%, 85.2%) and specificity was 96.6%, with a 95%CI of (90.3%, 99.3%). The proportion of correctly classified individuals was 87.5%, with a 95%CI of (81.2%, 92.3%). The results indicate that Cameriere's cut-off value of the third molar index (I3M=0.08) is useful in discriminating between Albanian adults and juveniles, and encourage us to test its suitability for determining the adult age in individuals from other populations. PMID:25459273

Cameriere, Roberto; Santoro, Valeria; Roca, Roberta; Lozito, Piercarlo; Introna, Francesco; Cingolani, Mariano; Gali?, Ivan; Ferrante, Luigi

2014-10-13

400

Effect of combination of trigger point injection and stellate ganglion block on non-odontogenic mandibular molar pain referred from masseter muscle: a case report.  

PubMed

We report a case of myofascial pain syndrome (MPS), manifested as nonodontogenic mandibular molar pain referred from the masseter muscle, relieved by a combination of trigger point injection (TPI) and stellate ganglion block (SGB). The patient was a 32-year-old woman who had experienced cold hypersensitivity in the right third mandibular molar 2 months prior to visiting our department. Subsequently, she had visited a family dentist and undergone pulpectomy under local anesthesia. She eventually visited our clinic because there was no marked change in her symptoms. On the first visit, no tooth abnormality was found and the patient was neither anxious nor depressive. Tender points were found in the right masseter and temporal muscles during muscle palpation. Referred pain radiating to the right mandibular molars was observed when pressure was applied to the central portion of the right masseter muscle. As a result, we diagnosed MPS based on evidence of nonodontogenic tooth pain caused by referred pain from the masseter muscle. We performed TPI with 2% lidocaine hydrochloride to the tender point in the masseter muscle. Although the visual analog scale (VAS) pain score dropped from 97 to 36, complete pain relief was not achieved. The TPI was effective for approximately 7 hrs, after which severe throbbing pain returned. The sustained nature of the tooth pain suggested that it was sympathetic nerve-dependent. Subsequently, we performed SGB, resulting in a reduction in the VAS pain score from 90 to 32. Therefore, we performed another TPI and the VAS pain score dropped to 0. We continued SGB and TPI for the next 3 days and the symptoms disappeared. Thus, a combination of TPI and SGB controlled MPS manifested as masseter muscle-mediated nonodontogenic tooth pain. PMID:24334631

Handa, Toshiyuki; Fukuda, Ken-ichi; Ichinohe, Tatsuya

2013-01-01

401

The molar volume of FeO-MgO-Fe2O3-Cr2O3-Al2O3-TiO2 spinels  

NASA Astrophysics Data System (ADS)

We define and calibrate a new model of molar volume as a function of pressure, temperature, ordering state, and composition for spinels in the supersystem (Mg, Fe2+)(Al, Cr, Fe3+)2O4 - (Mg, Fe2+)2TiO4. We use 832 X-ray and neutron diffraction measurements performed on spinels at ambient and in situ high- P, T conditions to calibrate end-member equations of state and an excess volume model for this system. The effect on molar volume of cation ordering over the octahedral and tetrahedral sites is captured with linear dependence on Mg2+, Al3+, and Fe3+ site occupancy terms. We allow standard-state volumes and coefficients of thermal expansion of the end members to vary within their uncertainties during extraction of the mixing properties, in order to achieve the best fit. Published equations of state of the various spinel end members are analyzed to obtain optimal values of the bulk modulus and its pressure derivative, for each explicit end member. For any spinel composition in the supersystem, the model molar volume is obtained by adding excess volume and cation order-dependent terms to a linear combination of the five end-member volumes, estimated at pressure and temperature using the high- T Vinet equation of state. The preferred model has a total of 9 excess volume and order-dependent parameters and fits nearly all experiments to within 0.02 J/bar/mol, or better than 0.5 % in volume. The model is compared to the current MELTS spinel model with a demonstration of the impact of the model difference on the estimated spinel-garnet lherzolite transition pressure.

Hamecher, Emily A.; Antoshechkina, Paula M.; Ghiorso, Mark S.; Asimow, Paul D.

2013-01-01

402

Influence of the Metal Nitrates to Citric Acid Molar Ratio on the Processing of Nickel Zinc Ferrite Nanocrystalline Powders Synthesized by a Sol-Gel Auto Combustion Method  

NASA Astrophysics Data System (ADS)

Nanocrystalline powder of the single phase nickel-zinc ferrite have been prepared by a sol-gel auto-combustion process. The nitrate-citrate gels were prepared from metal nitrates and citric acid solutions with various molar ratios of the metal nitrates to citric acid. The results showed that the nitrate citrate gels exhibit a self-propagating behavior after ignition in air. The thermal decomposition of nitrate-citrate gels and the phase evolution of the as-burnt powder were investigated by differential thermal analysis and thermogravimetry (DTA/TG) and X-ray diffraction (XRD) techniques respectively. Transmission electron microscope (TEM) was used to characterize the microstructure of the material. Magnetic properties were also measured by a vibrating sample magnetometer (VSM) with a maximum applied field of 10 kOe. The results also revealed that the molar ratio of the metal nitrates to citric acid has important effects on the formation temperature and the crystallite size which affect the magnetic properties of the nickel-zinc ferrite.

Barati, M. R.; Ebrahimi, S. A. Seyyed; Badiei, A.

2009-06-01

403

Ex-Vivo Evaluation of X-Ray Horizontal Angle for Separating the Canals of Four-Canal First Mandibular Molars  

PubMed Central

INTRODUCTION: A variety of mesial and distal projections have been suggested for separating the canals in a multi-canaled root. But there is no general agreement on the best angulation for each tooth. The purpose of this study was to evaluate the X-ray horizontal angle for separating the canals of four-canal first mandibular molars. MATERIALS AND METHODS: Forty four-canaled mandibular molars were selected. After preparation of coronal access cavities, files were inserted into the root canals and the specimens were radiographed at 10, 15, 20, 25 degrees mesial and distal horizontal angulations. Apices and canals were evaluated. Chi-square test was used for statistical analysis. RESULTS: Although 10° and 15° mesial and distal angulations were best for the most obvious apices manifestation (P<0.001), it was found that 20° mesial angulation is significantly better than the other cone angulations (P<0.001) for separating the root canals. CONCLUSION: 20° mesial angulation improved detection of both the canals and canal terminus visibility. PMID:24265637

Haghani, Jahangir; Raoof, Maryam; Pourahmadi, Sadegh

2008-01-01

404

Comparison of Hero 642 and K3 rotary nickel-titanium files in curved canals of molars and a systematic review of the literature.  

PubMed

The aim of the present study was to compare the root canal preparation ability of rotary nickel-titanium (NiTi) Hero 642 and K3 files in curved mandibular or maxillary molars. A total of 40 extracted mandibular molars with two separate mesial canals, an apical width of approximately size ?15 and a root canal curvature of 15-30° were randomly divided into two groups and instrumented using Hero 642 (n=20) or K3 files (n=20). Canal straightening, working length, transportation, cross-sectional area, minimum dentin thickness and the canal angle curvature degree were examined, and a systematic review of the literature was conducted. No statistically significant differences were observed between the two groups with regard to the mean degree of straightening, mean change in working length, mean transportation, amount of dentin removed or remaining minimum dentin thickness (P>0.05). The canal angle curvature decreased in the two groups postoperatively. The systematic review identified six studies, and overall the two files performed similarly in the majority of categories examined. Therefore, the rotary NiTi Hero 642 and K3 files demonstrated comparable shaping abilities and maintenance of working length. PMID:25187795

Cai, Hua-Xiong; Cheng, Hui-Ling; Song, Jie-Wen; Chen, Su-Ya

2014-10-01

405

Frequency of second mesiobuccal canal in permanent maxillary first molars using the operating microscope and selective dentin removal: A clinical study  

PubMed Central

Purpose: The aim of this study was to investigate whether the combination of operating microscope and selective dentin removal increased the frequency of second mesiobuccal (MB2) canal detection in permanent maxillary first molar teeth. Materials and Methods: One hundred fifty permanent maxillary first molars indicated for root canal treatment were randomly selected from patients belonging to the age group of 18–45 years irrespective of gender. After access cavity preparation and location of main canals, the MB2 canal orifice was sought in all teeth with an endodontic explorer under direct vision (Stage I), then under magnification with the aid of operating microscope (Stage II) and finally with the combined use of operating microscope and selective dentin removal (Stage III). Results: MB2 canals were detected in 36%, 54% and 72% of the teeth in Stages I–III, respectively. Conclusion: This study demonstrated that dental operating microscope when used along with adjunctive aids such as selective dentin removal/troughing and good clinical knowledge will increase the ability of dental clinician to locate MB2 canals. PMID:25684916

Das, Suroopa; Warhadpande, Manjusha M.; Redij, Saurabh A.; Jibhkate, N. G.; Sabir, Husain

2015-01-01

406

Valeriana officinalis L. for conscious sedation of patients submitted to impacted lower third molar surgery: A randomized, double-blind, placebo-controlled split-mouth study  

PubMed Central

Introduction: Anxiety is one of the components of patient stress in the dental office and is recognized as one of the main factors that negatively affect treatment. The control of anxiety can be performed through conscious sedation, for which benzodiazepine is the drug of choice in dental practice, however present side-effects. Objective: The objective of the following study is to evaluate the efficacy of Valeriana officinalis L. (Valerian) for control of anxiety during the third molar surgery. Materials and Methods: A single oral dose of either Valerian (100 mg) or placebo was randomly administered 1 h before each surgical procedure to 20 volunteers between 17 and 31 years of age. Anxiety level was assessed by physiological parameters (blood pressure and heart rate [HR]) and the observation of signs. Descriptive analysis, Chi-square test, Friedman test, Wilcoxon test and effect size test were performed (P < 0.05). Results: According to the researcher's (80%) and surgeon's (75%) evaluations, the patients treated with Valerian were calmer and more relaxed during surgery. Valerian had a greater effect on the maintenance of systolic blood pressure and HR after surgery. Conclusion: Valerian was more effective at controlling anxiety than a placebo when used for the conscious sedation of adult patients submitted to impacted lower third molar surgery. PMID:24741279

Pinheiro, Marcos Luciano Pimenta; Alcântara, Carlos Eduardo Pinto; de Moraes, Márcio; de Andrade, Eduardo Dias

2014-01-01

407

GENERAL: Low-temperature heat capacities and standard molar enthalpy of formation of 4-(2-aminoethyl)-phenol (C8H11NO)  

NASA Astrophysics Data System (ADS)

This paper reports that low-temperature heat capacities of 4-(2-aminoethyl)-phenol (C8H11NO) are measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of the temperature was fitted by the least square method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at the interval of 5 K. The energy equivalent, ?calor, of the oxygen-bomb combustion calorimeter has been determined from 0.68 g of NIST 39i benzoic acid to be ?calor = (14674.69±17.49)J.K-1. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision oxygen-bomb combustion calorimeter to be ?cU = -(32374.25±12.93)J.g-1. The standard molar enthalpy of combustion for the compound was calculated to be ?cHmominus = -(4445.47 ± 1.77) k. J · mol-1 according to the definition of enthalpy of combustion and other thermodynamic principles. Finally, the standard molar enthalpy of formation of the compound was derived to be ?fHmominus(C8H11NO, s) = -(274.68 ± 2.06) kJ · mol-1, in accordance with Hess law.

Di, You-Ying; Kong, Yu-Xia; Yang, Wei-Wei; Tan, Zhi-Cheng

2008-09-01

408

Low Temperature Heat Capacities and Standard Molar Enthalpy of Formation of 2-Pyrazinecarboxylic Acid (C5H4N2O2)(s).  

PubMed

Low-temperature heat capacities of 2-pyrazinecarboxylic acid (C5H4N2O2)(s) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of temperature was fitted by least squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at 10 K intervals. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision rotating-bomb combustion calorimeter to be ?cU = -(17839.40 ± 7.40) J g-1. The standard molar enthalpy of combustion of the compound was determined to be ?cH0m = -(2211.39 ± 0.92) KJ mol-1, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be ?fH0m = -(327.82 ± 1.13) kJ mol-1 in accordance with Hess law. PMID:24061733

Kong, Yu-Xia; Di, You-Ying; Yang, Wei-Wei; Gao, Sheng-Li; Tan, Zhi-Cheng

2010-06-01

409

Barium recovery by crystallization in a fluidized-bed reactor: effects of pH, Ba/P molar ratio and seed.  

PubMed

The effects of process conditions, including upward velocity inside the column, the amount of added seed and seed size, the pH value of the precipitant or the phosphate stream and the Ba/P molar ratio in a fluidized-bed reactor (FBR) were studied with a view to producing BaHPO? crystals of significant size and maximize the removal of barium. XRD were used to identify the products that were collected from the FBR. Experimental results show that an upward velocity of 48 cmmin(-1) produced the largest BaHPO? crystals with a size of around 0.84-1.0mm. The addition of seed crystals has no effect on barium removal. The use of a seed of a size in the ranges unseeded<0.149-0.29 mm<0.149 mm<0.29-0.42 mm produced increasing amounts of increasingly large crystals. The largest BaHPO? crystals were obtained at pH 8.4-8.8 with a Ba/P molar ratio of 1.0. In the homogeneous and heterogeneous processes, around 98% of barium was removed at pH 8.4-8.6 and [Ba]/[P]=1.0. The XRD results show that a significant amount of barium phosphate (Ba?(PO?)?) was obtained at pH 11. The compounds BaHPO? and BaO were present at a pH of below 10. PMID:24462085

Su, Chia-Chi; Reano, Resmond L; Dalida, Maria Lourdes P; Lu, Ming-Chun

2014-06-01

410

Prevalence of First Permanent Molar Caries in and Its Relationship to the Dental Knowledge of 9–12-Year Olds from Jeddah, Kingdom of Saudi Arabia  

PubMed Central

The carious status of the first permanent molar (FPM) was studied in 432 school children (aged 9–12 years) from a randomly selected primary schools from Sharfia area of Jeddah, Kingdom of Saudi Arabia. The sample consisted of 108 children from each age group of 9, 10, 11, and 12 years old. In total, 24.5% had all of their FPMs sound and 6% had all FPMs carious. The prevalence of four sound FPMs varied according to age with the highest (33%) amongst the nine-year olds and the lowest (16.5%) in the oldest children (12 years). Almost one-third (32.5%) of the children, who knew the age of eruption of the FPMs, had all of their molars sound. The children who had received advice regarding oral hygiene from a dentist or parent had more sound FPMs compared to the children who did not receive any advice. The number of carious FPMs increased with age. The prevalence of caries of the FPM was high and increased with increasing age. The level of knowledge had a positive correlation with the caries levels amongst this cohort of scholars. PMID:22461990

Al-Samadani, Khalid H. M.; Ahmad, Mohammad Sami

2012-01-01

411

A macroscopic model that connects the molar excess entropy of a supercooled liquid near its glass transition temperature to its viscosity.  

PubMed

For a deeply supercooled liquid near its glass transition temperature, we suggest a possible way to connect the temperature dependence of its molar excess entropy to that of its viscosity by constructing a macroscopic model, where the deeply supercooled liquid is assumed to be a mixture of solid-like and liquid-like micro regions. In this model, we assume that the mole fraction x of the liquid-like micro regions tends to zero as the temperature T of the liquid is decreased and extrapolated to a temperature T(g)(*), which we assume to be below but close to the lowest glass transition temperature T(g) attainable with the slowest possible cooling rate for the liquid. Without referring to any specific microscopic nature of the solid-like and liquid-like micro regions, we also assume that near T(g), the molar enthalpy of the solid-like micro regions is lower than that of the liquid-like micro regions. We then show that the temperature dependence of x is directly related to that of the molar excess entropy. Close to T(g), we assume that an activated motion of the solid-like micro regions controls the viscosity and that this activated motion is a collective motion involving practically all of the solid-like micro-regions so that the molar activation free energy ?g(a) for the activated motion is proportional to the mole fraction, 1 - x, of the solid-like micro regions. The temperature dependence of the viscosity is thus connected to that of the molar excess entropy s(e) through the temperature dependence of the mole fraction x. As an example, we apply our model to a class of glass formers for which s(e) at temperatures near T(g) is well approximated by s(e) ? 1 - T(K)?T with T(K) < T(g) ? T(g)(*) and find their viscosities to be well approximated by the Vogel-Fulcher-Tamman equation for temperatures very close to T(g). We also find that a parameter a appearing in the temperature dependence of x for a glass former in this class is a measure for its fragility. As this class includes both fragile and strong glass formers, our model applies to both fragile and strong glass formers. We estimate the values of three parameters in our model for three glass formers in this class, o-terphenyl, 3-bromopentane, and Pd(40)Ni(40)P(20), which is the least fragile among these three. Finally, we also suggest a way to test our assumption about the solid-like and liquid-like micro regions by means of molecular dynamics simulations of model liquids. PMID:23206018

Matsuoka, Hiroshi

2012-11-28

412

CBVT analysis of canal configuration of the mesio-buccal root of maxillary first permanent molar teeth: An in vitro study  

PubMed Central

Context: For successful endodontic treatment, it's imperative to locate and obturate all root canals. As concluded by Ingle, the major cause for failure of root canal therapy is in ability to recognize all theexisting canals and subsequent failure in their obturation. Aim: To analyze the canal configuration of the mesio-buccal root of maxillary first permanent molar teeth. Materials and Methods: A total of 30 recently extracted human permanent maxillary first molars were collected and stored in a container with 5% Sodium Chloride solution for four days. Teeth with open apices, external resorption, improperly formed roots and teeth with previous restorations were excluded. Using the dental modeling wax, teeth were arranged in a ‘U’ shaped arch with roots embedded inside the wax and occlusal surface remaining free. 10 teeth were arranged in each arch and three such sample plates were prepared. Flat surface of the base encasing enabled the plate to be mounted on flat plastic bite plate. With bite plate roughly centered in the focal trough area Axial, Coronal and Sagittal section Cone-Beam Computed Tomography (CBCT) images were taken with Kodak 9000 Extra-oral Imaging System. Images displayed on a monitor were inspected by two endodontists using Kodak Dental Imaging Software 3D Module V2.2. Statistical Analysis: When the data was observed, it was found that 24 teeth out of total 30 teeth examined showed some variation (i.e. possible additional canal) along the length of the mesio-buccal root canal. Out of these 24 teeth, 13 showed presence of additional canal at coronal third, 7 showed presence of additional canal at middle third and four showed presence of additional canal in apical third level. Percentage analysis was done as there was no group comparison to be done. Results: Cone-Beam Volumetric Tomography (CBVT) evaluation positively identified the variations in mesio-buccal canal in 80% of samples. Out of these, 54.16% were in coronal 3rd, 29.16% in middle 3rd and 16.66% were in apical 3rd. Conclusion: Within the limitations of this study, it can be concluded that- (1) more than half of maxillary first molars have four canals and (2) most of the additional canals were located in the MBR and CBVT is a good diagnostic tool to help diagnose these additional canals. Further investigations using larger sample sizes would be helpful. PMID:23293481

Shenoi, R. Pratima; Ghule, Hrishikesh M.

2012-01-01

413

An alternative approach to extruding a vertically impacted lower third molar using an orthodontic miniscrew: A case report with cone-beam CT follow-up  

PubMed Central

One of the most common oral surgical procedures is the extraction of the lower third molar (LTM). Postoperative complications such as paresthesia due to inferior alveolar nerve (IAN) injury are commonly observed in cases of horizontal and vertical impaction. The present report discusses a case of a vertically impacted LTM associated with a dentigerous cyst. An intimate contact between the LTM roots and the mandibular canal was observed on a panoramic radiograph and confirmed with cone-beam computed tomographic (CBCT) cross-sectional cuts. An orthodontic miniscrew was then used to extrude the LTM prior to its surgical removal in order to avoid the risk of inferior alveolar nerve injury. CBCT imaging follow-up confirmed the success of the LTM orthodontic extrusion. PMID:24944969

No-Cortes, Juliana; Cavalcanti, Marcelo Gusmão Paraíso; Arita, Emiko Saito

2014-01-01

414

Effects of the Fe3+/Sr2+ molar ratio on the exchange-coupling of the composite and single-phase SrFe12O19  

NASA Astrophysics Data System (ADS)

It has been systematically investigated about the magnetic properties of the composite and single-phase SrFe12O19 prepared with the precursor of different Fe3+/Sr2+ molar ratios of 12:1, 11:1 and 10:1, respectively. With increasing the calcinations temperature, the coercivity of all samples decreases which can be determined by the stress model. The ?m(H) results indicate that the intergrain exchangecoupling interaction exists both in compos