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1

Aproximación a un protocolo quirúrgico para el manejo de dientes supernumerarios: Evaluación de un caso y revisión de la literatura  

Microsoft Academic Search

Palabras clave: Diente supernumerario, Cirugía oral, Protocolo quirúrgico. SUMMARY Introduction: The supernumerary teeth (DSN) are development anomalies, which typical manifestations are sequence and eruption modifications. Methodology: We did a search in Medline and Pubmed with definied criteria of selection between the year 1985 and 2005. Results: 13 articles were found useful for the review, of which 2 were literature reviews.

Olate Morales S; Thomas Maldonado; Alveal Campuzano R

2

Molar distalization with bimetric molar distalization arches.  

PubMed

The aim of this study was to observe the clinical and cephalometric effects of intra-oral distalization with the maxillary bimetric arches. 3 girls and 1 boy with a mean age of 13.5 years with Class II skeletal and dental relationship were selected. Care was taken to select patients having a normal vertical growth pattern. Lateral cephalograms were taken at the beginning and at the end of the distalization period, which was approximately 3 months. To observe the distal movement, a metal marker was attached to the distal end of the buccal tube of the first molar. On each lateral cephalometric radiograph a reference plane perpendicular to the occlusal plane and passing through the point Sella was drawn to assess the amount of distalization. Cephalometric measurements indicated that the upper molars moved approximately 3 mm distally and that the lower incisors were proclined. PMID:9582621

Küçükkele?, N; Do?anay, A

1994-09-01

3

Endodontic treatment of molars  

PubMed Central

Objective Commissioned by the German Institute of Medical Documentation and Information (DIMDI) the Austrian Health Institute (ÖBIG) prepared a HTA report on the long-term effectiveness of endodontic treatment (root canal treatment, RCT) of molars. The focus is to examine factors influencing the outcome of endodontic treatment and showing their impact on long-term results. Additionally, economic aspects of root canal treatment in Germany are discussed. Methodology By performing a systematic literature search in 29 databases (e.g. MEDLINE), the Cochrane Library and by hand searching two peer-reviewed endodontic journals the authors could identify 750 relevant articles, of which finally 18 qualified for assessment. Results The findings show that the most relevant factor influencing the long-term outcome of endodontic treatment is the preoperative status of a tooth. The lowest success rates are reported for molars with a preoperative devital or necrotic pulp and persisting periapical lesions (so called periapical disease). Discussion Even if there is no positive selection of patients and the RCT is performed by a normal dentist rather than an endodontist - a fact which is very common - long-term success rates of more then 90% are possible. The overall success rates for endodontic treatment of molars therefore seem to be similar to those of other tooth-types. Conclusions Especially primary, conventional (i.e. non-surgical) root canal treatment is an effective and efficient therapy for endodontically ill molars, especially if no large periapical lesion persists. Nonetheless, a long term successful endodontic therapy requires a thorough assessment of the pre-operative status of the molar and treatment according to established guidelines.

Habl, Claudia; Bodenwinkler, Andrea; Sturzlinger, Heidi

2006-01-01

4

Taurodontism in deciduous molars.  

PubMed

Taurodont teeth are characterised by large pulp chambers at the expense of roots. An enlarged pulp chamber, apical displacement of the pulpal floor and no constriction at the level of the cement-enamel junction are the characteristic features of taurodont tooth. It appears more frequently as an isolated anomaly but its association with syndromes and other abnormalities have also been reported. Permanent dentition is more commonly affected than deciduous dentition. This paper presents a case report of taurodontism in relation to mandibular deciduous second molars. PMID:23737594

Bafna, Yash; Kambalimath, H V; Khandelwal, Vishal; Nayak, Prathibha

2013-06-03

5

Molar and incisor changes with Wilson rapid molar distalization.  

PubMed

The purpose of this study was to determine the magnitude and direction of maxillary and mandibular first molar and incisor changes that occur during Class II molar correction with Wilson "rapid molar distalization." Nineteen patients (13 females, 6 males) were selected from the clinic at Loma Linda University Department of Orthodontics. All patients received maxillary bimetric distalizing arches (BDA), and either a mandibular three-dimensional lingual arch, with or without a passive 0.016 x 0.016-inch utility arch, or a traditional edgewise full banded and bonded arch. The arches were activated with open coil spring and Class II intermaxillary elastics. A total of five activations were completed or until visual inspection revealed a Class I molar relation. Prestudy and poststudy lateral cephalometric radiographs were taken with molar bands cemented. Dental changes were determined, with Ricketts superimpositions. The mean change in molar relation measured at the occlusal plane was 4.1 mm. The mean maxillary molar distalization was 2.16 mm, with 7.8 degrees of tip. The rate of maxillary molar movement was 0.56 mm per month. The mean mandibular molar mesial movement was 1.38 mm. The maxillary incisors protruded a mean of 0.3 mm, and extruded a mean of 1.6 mm. Except for the edgewise sample, all mandibular molars moved mesially further than the incisors, reducing the mandibular arch length. The presence of erupted maxillary second molars did not correlate with the rate of maxillary first molar movement, magnitude of movement, or amount of tipping that occurred. PMID:8249931

Muse, D S; Fillman, M J; Emmerson, W J; Mitchell, R D

1993-12-01

6

Noncompliance unilateral maxillary molar distalization:.  

PubMed

The aim of this prospective study was the three-dimensional (3-D) analysis of tooth movements after unilateral upper molar distalization by means of a noncompliance intraoral appliance, the Keles slider. This appliance exerts a distalizing force of 150 g at approximately the level of the center of resistance of the upper first molar. Twelve patients (six girls and six boys with a mean age of 13.1 years) with a unilateral Class II molar relationship participated in the study. Dental casts were taken immediately before placement and after removal of the appliance. The casts were digitized using a 3-D surface laser scanner and superimposed on a predefined area of the palate. The average unilateral upper first molar distal movement was 3.1 mm (range: 2.4 to 5.3 mm). Anchorage loss was expressed by a 2.1 mm (range: 0.8 to 3.8 mm) proclination of the central incisors and a 6.1 degrees mesial inclination of the ipsilateral first premolar (range: 1.7 degrees to 12.3 degrees ). There was approximately 1 mm of midline deviation toward the contralateral side and a 1.6 mm (range: 0.8 to 2.3 mm) buccal displacement of the contralateral first premolar. A substantial variation was observed among patients. Noncompliance unilateral upper molar distalization was an efficient treatment approach. There was, however, a substantial anchorage loss. Case selection is strongly recommended because significant anterior crowding, ectopic canines, or spacing can lead to significant anchorage loss. PMID:16637715

Mavropoulos, Anestis; Sayinsu, Korkmaz; Allaf, Ferdi; Kiliaridis, Stavros; Papadopoulos, Moschos A; Keles, Ahmet Ozlem

2006-05-01

7

Molar distalization with the Herbst appliance  

Microsoft Academic Search

This article reviews the dental effects of the Herbst appliance as well as itslong-term effects on the dentition. The Herbst appliance exhibits a pronounced high-pull headgear effect on the maxillary molars. Without retention, the molars tend to return to their former anteroposterior positions after the removal of the appliance. These distal movements of the maxillary molars are favorable in Class

Meson Lai

2000-01-01

8

Molar versus as a paradigm clash.  

PubMed Central

The molar view of behavior arose in response to the demonstrated inadequacy of explanations based on contiguity. Although Dinsmoor's (2001) modifications to two-factor theory render it irrefutable, a more basic criticism arises when we see that the molar and molecular views differ paradigmatically. The molar view has proven more productive.

Baum, W M

2001-01-01

9

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.

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

2009-01-01

10

Maxillary first molar with two root canals.  

PubMed

Knowledge regarding the anatomic morphology of maxillary molars is absolutely essential for the success of endodontic treatment. The morphology of the permanent maxillary first molar has been reviewed extensively; however, the presence of two canals in a two-rooted maxillary first molar has rarely been reported in studies describing tooth and root canal anatomies. This case report presents a patient with a maxillary first molar with two roots and two root canals, who was referred to the Department of Endodontics, Tabriz University of Medical Sciences, Iran. PMID:23862051

Rahimi, Saeed; Ghasemi, Negin

2013-05-09

11

Molar development in common chimpanzees ( Pan troglodytes)  

Microsoft Academic Search

Numerous studies have reported on enamel and dentine development in hominoid molars, although little is known about intraspecific incremental feature variation. Furthermore, a recent histological study suggested that there is little or no time between age at chimpanzee crown completion and age at molar eruption, which is unlikely given that root growth is necessary for tooth eruption. The study presented

T. M. Smith; D. J. Reid; M. C. Dean; A. J. Olejniczak; L. B. Martin

2007-01-01

12

The demographics of molar pregnancies in BPKIHS.  

PubMed

This is an analysis of the incidence of molar pregnancies and those of complete and partial molar pregnancies across the reproductive age range for BP Koirala Institute of Health Sciences (BPKIHS) in the period 2010-2011. Patients with molar pregnancies registered with BPKIHS from January 2008 to January 2010 were identified. The overall number of molar pregnancies registered was compared to the number of maternities (live births and still births) and total viable conceptions for this year. A retrospective study of 64 cases of molar pregnancies recorded at BPKIHS during the two year time was done. Medical records were reviewed. Incidence, clinical presentation and methods of diagnosis were studied. During the study period, there were 37 complete moles, 23 partial moles, 1 persistent gestational trophoblastic tumor, 1 choriocarcinoma, and 2 invasive moles. The incidence of molar pregnancy was 3.94 per 1000 deliveries. Median distribution was at 22 years of age, and majority (67%) presented during early second trimester. Twenty one (32.8%) women were of blood group A positive and ten (15.6%) presented with severe form of anemia. This study provides detailed data regarding the incidence of partial and complete molar pregnancies with increasing maternal age. It confirms the relation of molar pregnancy with age, and blood group. Complete mole had the highest incidence, affecting mostly younger age group, and usually in the first half of their pregnancy. PMID:22710543

Koirala, A; Khatiwada, P; Giri, A; Kandel, P; Regmi, M; Upreti, D

13

Lingual nerve paresthesia following third molar surgery  

Microsoft Academic Search

Lingual nerve anesthesia, paresthesia, and dysesthesia are possible side effects of third molar extraction. These unwanted complications are frequently disturbing to both the patient and practitioner. The incidence of lingual nerve damage following third molar surgery is more frequent than once thought. Six hundred questionnaires were sent to randomly selected Fellows of the American Association of Oral and Maxillofacial Surgeons

Allen F Fielding; Dominic P Rachiele; Gordon Frazier

1997-01-01

14

Molar development in common chimpanzees (Pan troglodytes).  

PubMed

Numerous studies have reported on enamel and dentine development in hominoid molars, although little is known about intraspecific incremental feature variation. Furthermore, a recent histological study suggested that there is little or no time between age at chimpanzee crown completion and age at molar eruption, which is unlikely given that root growth is necessary for tooth eruption. The study presented here redefines growth standards for chimpanzee molar teeth and examines variation in incremental features. The periodicity of Retzius lines in a relatively large sample was found to be 6 or 7 days. The number of Retzius lines and cuspal enamel thickness both vary within a cusp type, among cusps, and among molars, resulting in marked variation in formation time. Daily secretion rate is consistent within analogous cuspal zones (inner, middle, and outer enamel) within and among cusp types and among molar types. Significantly increasing trends are found from inner to outer cuspal enamel (3 to 5 microns/day). Cuspal initiation and completion sequences also vary, although sequences for mandibular molar cusps are more consistent. Cusp-specific formation time ranges from approximately 2 to 3 years, increasing from M1 to M2, and often decreasing from M2 to M3. These times are intermediate between radiographic studies and a previous histological study, although both formation time within cusps and overlap between molars vary considerably. Cusp-specific (coronal) extension rates range from approximately 4 to 9 microns/day, and root extension rates in the first 5 mm of roots range from 3 to 9 microns/day. These rates are greater in M1 than in M2 or M3, and they are greater in mandibular molars than in respective maxillary molars. This significant enlargement of comparative data on nonhuman primate incremental development demonstrates that developmental variation among cusp and molar types should be considered during interpretations and comparisons of small samples of fossil hominins and hominoids. PMID:17084441

Smith, T M; Reid, D J; Dean, M C; Olejniczak, A J; Martin, L B

2006-09-23

15

Unilateral molar distalization with a modified slider.  

PubMed

Although there are numerous publications on bilateral non-compliance molar distalization appliances, there is limited information on problems such as asymmetrical unilateral Class II malocclusions. The aim of the present investigation was to examine the distalization of molars unilaterally in patients with a unilateral Class II molar relationship utilizing a Keles Slider, designed without a bite plane. Ten girls (mean age 13.94 +/- 2.13 years) and seven boys (mean age 13.12 +/- 1.51 years) comprised the study material. Following insertion of the appliance, the patients were seen monthly and the screw was reactivated every 2 months. After a super-Class I molar relationship was achieved, the appliance was removed and the molars were stabilized with a Nance appliance for 2 months before the second-phase of orthodontic treatment. The Nance appliance was maintained in the palate until the end of canine distalization. Lateral cephalometric radiographs were obtained before and immediately after insertion of the molar distalizer. The results showed that the maxillary first molars were distalized bodily on average by 2.85 mm. The maxillary first premolars moved forward bodily 2 mm and were extruded 2.03 mm. In all, 1.32 mm of protrusion, 1.12 mm of extrusion, and 1.79 degrees of proclination of the upper incisors were observed. The mandibular incisors and mandibular molars erupted 0.83 and 0.95 mm, respectively. The unilateral Keles Slider distalized molars successfully to a Class I molar relationship. PMID:16648210

Sayinsu, Korkmaz; Isik, Fulya; Allaf, Ferdi; Arun, Tülin

2006-04-28

16

How will mandibular third molar surgery affect mandibular second molar periodontal parameters?  

PubMed Central

Background: Several conflicting findings have been published in the previous literature regarding the effects of impacted third molar surgery on the periodontal parameters of the adjacent second molar; some authors have shown improvement of periodontal health distal to the adjacent second molar, whilst others have demonstrated loss of attachment level (AL) and reduction of alveolar bone height. The purpose of this study was to evaluate the changes in periodontal health parameters distal to the adjacent second molar following extraction of an impacted third molar. Materials and Methods: Out of 50 patients participated in the study, 42 patients completed the study. The mean age of the sample was 20.9 (range, 18-25) years. All teeth were mesioangular impacted mandibular third molars categorized at C1 class based on the Pell and Gregory classification. All surgeries were performed by one surgeon and the same surgeon recorded the pre-operative and post-operative measurements of probing depth (PD) and AL on the distobuccal aspect of the second molars. Data analysis were carried out with the SPSS software (version 19), using the paired-samples t-test and one sample t-test. Results: Surgical extraction of impacted mandibular third molar resulted in a significant increase of PD on the distobuccal aspect of the second molars, whereas AL was decreased significantly after surgery (P < 0.05). Conclusion: Unlike plenty of researches that have shown improvement of periodontal parameters of the second molar after extraction of impacted third molar, our study showed a significant increase in PD at the distal aspect of the second molar. Further follow-up on clinical and radiological parameters are required for more profound understanding of the long-term effects of third molar extraction on the periodontal parameters of the adjacent second molar.

Tabrizi, Reza; Arabion, Hamidreza; Gholami, Mehdi

2013-01-01

17

Mandibular first molar with three distal canals  

PubMed Central

With the increasing number of reports of aberrant root canal morphology, the clinician needs to be aware of the variable anatomy. Various case reports have been published with the finding of middle mesial canal in mandibular first molar, however finding of middle distal canal in distal root of mandibular first molar is rare. This case report describes root canal treatment of two rooted mandibular first molar with five root canals (three in distal and two in mesial root), and Sert and Bayirli Type XVIII canal configuration in distal root.

Jain, Shweta

2011-01-01

18

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

...Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents...PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance...Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents...atmosphere. b MHC = molar heat content (higher heating...

2013-07-01

19

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.

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

2011-01-01

20

Canal complexity of a mandibular first molar  

PubMed Central

The endodontic treatment of a mandibular molar with aberrant canal configuration can be diagnostically and technically challenging. This case report presents the treatment of a mandibular first molar with five root canals, of which three were located in the mesial root. A third canal was found between the mesiobuccal and mesiolingual root canals. The morphological pattern of separate apical terminations of three mesial root canals with separate orifices, as manifested in this case, is a rare one.

Poorni, S; Kumar, RA; Indira, R

2009-01-01

21

The molar volume of silicon [Avogadro constant  

Microsoft Academic Search

A reevaluation has been made of the density and molar mass data for the silicon single crystals used in three Avogadro projects in which the authors' institutions are cooperating. A value of 12.058 825(15) cm 3 mol-1 at 22.5°C was obtained for the ratio M(Si)\\/?(Si), which is considered our present best estimate of the silicon molar volume. This implies for

P. De Bievre; S. Valkiers; R. Gonfiantini; P. D. P. Taylor; H. Bettin; F. Spieweck; A. Peuto; S. Pettorruso; M. Mosca; K. Fujii; M. Tanaka; Y. Nezu; A. J. Leistner; W. J. Giardini

1997-01-01

22

Molars and incisors: show your microarray IDs  

PubMed Central

Background One of the key questions in developmental biology is how, from a relatively small number of conserved signaling pathways, is it possible to generate organs displaying a wide range of shapes, tissue organization, and function. The dentition and its distinct specific tooth types represent a valuable system to address the issues of differential molecular signatures. To identify such signatures, we performed a comparative transcriptomic analysis of developing murine lower incisors, mandibular molars and maxillary molars at the developmental cap stage (E14.5). Results 231 genes were identified as being differentially expressed between mandibular incisors and molars, with a fold change higher than 2 and a false discovery rate lower than 0.1, whereas only 96 genes were discovered as being differentially expressed between mandibular and maxillary molars. Numerous genes belonging to specific signaling pathways (the Hedgehog, Notch, Wnt, FGF, TGF?/BMP, and retinoic acid pathways), and/or to the homeobox gene superfamily, were also uncovered when a less stringent fold change threshold was used. Differential expressions for 10 out of 12 (mandibular incisors versus molars) and 9 out of 10 selected genes were confirmed by quantitative reverse transcription-PCR (qRT-PCR). A bioinformatics tool (Ingenuity Pathway Analysis) used to analyze biological functions and pathways on the group of incisor versus molar differentially expressed genes revealed that 143 genes belonged to 9 networks with intermolecular connections. Networks with the highest significance scores were centered on the TNF/NF?B complex and the ERK1/2 kinases. Two networks ERK1/2 kinases and tretinoin were involved in differential molar morphogenesis. Conclusion These data allowed us to build several regulatory networks that may distinguish incisor versus molar identity, and may be useful for further investigations of these tooth-specific ontogenetic programs. These programs may be dysregulated in transgenic animal models and related human diseases leading to dental anomalies.

2013-01-01

23

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

24

A new approach in maxillary molar distalization: intraoral bodily molar distalizer.  

PubMed

The objectives of our study were to achieve bodily molar distalization, avoid distal tipping of molars, eliminate the need for patient cooperation (no headgear, no elastics, and no esthetic and social concern), and finally to minimize the treatment period and maximize the treatment efficiency. The study was carried out on 5 males and 10 females, a total of 15 patients. Mean age for the study group was 13.53 years. Dentally, all the patients had Class II molar relationship on both sides. The patients were in permanent dentition, second molars were erupted, and the lower dental arch was well aligned. Patients showed normal or sagittally directed growth pattern. Lateral cephalograms and study models were taken and analyzed before and after molar distalization. In the present study, in order to achieve maxillary molar distalization, a new intraoral appliance was developed. The intraoral bodily molar distalizer (IBMB) was composed of 2 parts: the anchorage unit and the distalizing unit. The anchorage unit was a wide Nance button, and the active unit consisted of distalizing springs. The springs had 2 components: the distalizer section of the spring applied a crown tipping force, while the uprighting section of the spring applied a root uprighting force on the first molars. A total of 230 g of distalizing force was used on both sides. After the distal movement of the first molars, the cephalometric results of 15 patients showed the following. Maxillary first molars were moved distally by an average of 5.23 mm (P <.001) without tipping or extrusion. Maxillary first premolars were moved 4.33 mm mesially (P <.001), tipped 2.73 degrees distally (P <.05), and extruded by 3.33 mm (P <.001). Maxillary central incisors were proclined by an average of 4.7 mm (P <.001) and tipped 6.73 degrees labially (P <.01). Model analysis showed that maxillary first molars were not rotated, and intermolar distance did not change after distal movement of molars. In conclusion, unlike most of the other molar distalization mechanics, this newly developed device achieved (1) bodily distal movement of maxillary molars and (2) eliminated dependence on patient cooperation and did not require headgear wear for molar root uprighting. PMID:10629518

Keles, A; Sayinsu, K

2000-01-01

25

A new approach in maxillary molar distalization: Intraoral bodily molar distalizer  

Microsoft Academic Search

The objectives of our study were to achieve bodily molar distalization, avoid distal tipping of molars, eliminate the need for patient cooperation (no headgear, no elastics, and no esthetic and social concern), and finally to minimize the treatment period and maximize the treatment efficiency. The study was carried out on 5 males and 10 females, a total of 15 patients.

Ahmet Keles; Korkmaz Sayinsu

2000-01-01

26

Oxygen from Hydrogen Peroxide. A Safe Molar Volume-Molar Mass Experiment.  

ERIC Educational Resources Information Center

Describes a molar volume-molar mass experiment for use in general chemistry laboratories. Gives background technical information, procedures for the titration of aqueous hydrogen peroxide with standard potassium permanganate and catalytic decomposition of hydrogen peroxide to produce oxygen, and a discussion of the results obtained in three…

Bedenbaugh, John H.; And Others

1988-01-01

27

Oxygen from Hydrogen Peroxide. A Safe Molar Volume-Molar Mass Experiment.  

ERIC Educational Resources Information Center

|Describes a molar volume-molar mass experiment for use in general chemistry laboratories. Gives background technical information, procedures for the titration of aqueous hydrogen peroxide with standard potassium permanganate and catalytic decomposition of hydrogen peroxide to produce oxygen, and a discussion of the results obtained in three…

Bedenbaugh, John H.; And Others

1988-01-01

28

Estudio retrospectivo de 145 dientes supernumerarios  

Microsoft Academic Search

Objective: The goal of the present retrospective study is to describe the distribution of the supernumerary teeth in a population of patients that have been attended at the Public Clinic of the Department of Oral Surgery. Background: Supernumerary teeth and multiple hyperdontia are usually associated with different syndromes, such as Gardner syndrome, or with facial fissures; however, they can appear

Paula Fernández Montenegro; Eduard Valmaseda Castellón; Leonardo Berini Aytés; Cosme Gay Escoda

29

Molar and molecular views of choice.  

PubMed

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 view has a long history both in early thought about reflexes and in associationism, and, although it was helpful to getting a science of behavior started, it has outlived its usefulness. The molar view stems from a conviction that behavior is continuous, as argued by John Dewey, Gestalt psychologists, Karl Lashley, and others. The molar paradigm views behavior as inherently extended in time and composed of activities that have integrated parts. In the molar paradigm, activities vary in their scale of organization--i.e., as to whether they are local or extended--and behavior may be controlled sometimes by short-term relations and sometimes by long-term relations. Applied to choice, the molar paradigm rests on two simple principles: (a) all behavior constitutes choice; and (b) all activities take time. Equivalence between choice and behavior occurs because every situation contains more than one alternative activity. The principle that behavior takes time refers not simply to any notion of response duration, but to the necessity that identifying one action or another requires a sample extended in time. The molecular paradigm's momentary responses are inferred from extended samples in retrospect. In this sense, momentary responses constitute abstractions, whereas extended activities constitute concrete particulars. Explanations conceived within the molecular paradigm invariably involve hypothetical constructs, because they require causes to be contiguous with responses. Explanations conceived within the molar paradigm retain direct contact with observable variables. PMID:15157981

Baum, William M

2004-06-30

30

Characteristics of Women with Recurrent Molar Pregnancies  

Microsoft Academic Search

Objectives. The aim of this study was to examine the incidence and characteristics of women who develop a second molar pregnancy after a previous episode of gestational trophoblastic disease.Methods. A retrospective analysis was carried out on completed registration forms from referring hospitals in the North of England to the Sheffield Trophoblastic Screening Service over a 13-year period. All cases of

P. C. Lorigan; S. Sharma; N. Bright; R. E. Coleman; B. W. Hancock

2000-01-01

31

Mass versus molar doses, similarities and differences.  

PubMed

Generally, they are two systems expressing the amounts of active substance in a given drug product, i.e. mass and molar dose. Currently, the dose system based on the mass is widely used in which doses are expressed in grams or milligrams. On the other hand, the molar dose system is in direct relation to the number of molecules. Hence, the objective of this work was to compare both systems in order to find their advantages and disadvantages. Active substances belonging to the groups of antibiotics, nootropic agents, beta-blockers, vitamins, GABA-analog, COX-2 inhibitors, calcium channel antagonists, benzodiazepine receptor agonists, lipid-modifying agents (fibrates), non-steroidal anti-inflammatory drugs (profens), estrogens, neuroleptics, analgesics and benzodiazepines were considered. Moreover, products containing two active substances were also taken into account. These are mixtures of hydrochlorothiazide with active substances influencing the renin-angiotensin system and combined oral contraceptives. For each active substance, belonging to the groups mentioned above molar doses were calculated from mass doses and molar mass. Hence, groups of drugs with a single active substance, drugs with similar pharmacological activities, pharmaceutical alternatives, and drugs with a single active ingredient manufactured in different doses were compared in order to find which dose system describes more adequately differences between and within the groups mentioned above. Comparisons were supported by a number of equations, which theoretically justify the data, and relationships derived from calculations. PMID:19069248

Chmielewska, A; Lamparczyk, H

2008-11-01

32

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

33

Endodontic therapy on the mandibular second molar: easiest to treat of the difficult, molar teeth.  

PubMed

Molar teeth present more problems during endodontic therapy than do bicuspid or anterior teeth. The major reasons for this are that molars can have complicated canal systems with unexpectedly large numbers of teeth with four canals, and they often have quite curved canals, which are more difficult to prepare and fill. The mandibular second molar generally is the easiest of these difficult teeth to treat, but they do have some areas of complication, too. The mesial root almost always has two--not one--canals and a rarely described condition, the C-shaped canal system, may be present. PMID:7987904

Weine, F S

1994-09-01

34

Human dental age estimation combining third molar(s) development and tooth morphological age predictors.  

PubMed

In the subadult age group, third molar development, as well as age-related morphological tooth information can be observed on panoramic radiographs. The aim of present study was to combine, in subadults, panoramic radiographic data based on developmental stages of third molar(s) and morphological measurements from permanent teeth, in order to evaluate its added age-predicting performances. In the age range between 15 and 23 years, 25 gender-specific radiographs were collected within each age category of 1 year. Third molar development was classified and registered according the 10-point staging and scoring technique proposed by Gleiser and Hunt (1955), modified by Köhler (1994). The Kvaal (1995) measuring technique was applied on the indicated teeth from the individuals' left side. Linear regression models with age as response and third molar-scored stages as explanatory variables were developed, and morphological measurements from permanent teeth were added. From the models, determination coefficients (R (2)) and root-mean-square errors (RMSE) were calculated. Maximal-added age information was reported as a 6 % R² increase and a 0.10-year decrease of RMSE. Forensic dental age estimations on panoramic radiographic data in the subadult group (15-23 year) should only be based on third molar development. PMID:22885953

Thevissen, P W; Galiti, D; Willems, G

2012-08-12

35

Therapeutic choices in the molar region.  

PubMed

Treatment of the damaged molar often presents a set of challenges unique to the posterior dentition. Traditional dental treatments continue to be refined to improve the prognosis when treating the posterior dentition. Daily treatment-planning decisions include whether to treat with conventional dental or implant therapeutic approaches, and involve consideration of local host factors as well as limitations in specific therapeutic approaches. This article will review some of the factors to consider in these treatment-planning decisions. PMID:12041803

Ducar, John P; Tsutsui, Fred; Merin, Robert L

2002-05-01

36

Can histopathologists reliably diagnose molar pregnancy?  

PubMed Central

AIMS--To assess the degree of difficulty in diagnosing partial mole by analysing intraobserver and interobserver agreement among a group of pathologists for these diagnoses. METHODS--Fifty mixed cases of partial mole, complete mole, and non-molar pregnancy were submitted to seven histopathologists, two of whom are expert gynaecological pathologists; the other five were district general hospital consultants, one of whom works in Australia. These participants gave each slide a firm diagnosis of either partial mole, complete mole, or non-molar pregnancy. Some 12 months later, the slides were recorded and again submitted for a second diagnostic round to assess intraobserver as well as interobserver agreement. Standard histological criteria for each diagnostic category were circulated with the slides. RESULTS--kappa statistics showed that complete mole could be reliably distinguished from non-molar pregnancy, but neither non-molar pregnancy nor complete mole could be easily differentiated from partial mole. In only 35 out of 50 cases was there agreement between five or more of the seven participants. Agreement between the expert gynaecological pathologists was no better than for others in the group. Interestingly, the intraobserver agreement for each pathologist was good to excellent. CONCLUSIONS--These results imply that the reported histological criteria are either not being applied consistently or that they are lacking in practical use. An atypical growth pattern of trophoblast, rather than the polar accentuation seen in normal first trimester pregnancies, seems to be the important diagnostic histological feature for partial mole. Ploidy studies might also help with problem cases. Images

Howat, A J; Beck, S; Fox, H; Harris, S C; Hill, A S; Nicholson, C M; Williams, R A

1993-01-01

37

Enzyme Molar Fractions: A Powerful Tool for Understanding Enzyme Kinetics.  

ERIC Educational Resources Information Center

|Deduces the relationship between reduced velocity and molar fractions for productive enzyme complexes; obtains the mathematical expression of molar fractions for an enzyme with two specific binding sites per molecule; and proposes a useful plot to follow the dependence of enzyme molar fractions with the concentration of one of its ligands. (JN)|

Serra, Juan L.; And Others

1986-01-01

38

Radiographic evaluation of mandibular third molar eruption space  

Microsoft Academic Search

Objective. The purpose of this study was to investigate variables in third molar and arch dimensions among subjects with impacted and erupted mandibular third molars. Study Design. Standardized panoramic radiographs were taken for 134 subjects (60 males and 74 females with 213 third molars) with an average age of 19.8 years. For the impacted group, only those who had mesioangular

Faiez N. Hattab; Elham S. J. Abu Alhaija

1999-01-01

39

Attachment Levels and Crevicular Depths at the Distal of Mandibular Second Molars Following Removal of Adjacent Third Molars.  

National Technical Information Service (NTIS)

The effect of root planing and curettage on the crevicular depth and periodontal attachment at the distal of mandibular second molars following removal of adjacent impacted or partially erupted third molars was evaluated in eighteen patients between the a...

W. H. Osborne A. J. Snyder T. R. Tempel

1981-01-01

40

[Ectopic molar tooth in the maxillary sinus].  

PubMed

The development of intranasal ectopic teeth is rare. Although they are more commonly seen in the palate and maxillary sinus, they can also be found in the mandibular condyle, coronoid process, and nasal cavity. A 30-year-old male patient presented with a complaint of headache. Computed tomography of the paranasal sinuses showed a bony mass in the right maxillary sinus wall, 1 cm in size. He did not have any history of maxillofacial trauma or operation. The mass was removed via a Caldwell-Luc procedure. It looked like a tooth. Histopathologic diagnosis was made as ectopic molar tooth. The patient was asymptomatic two weeks after the operation. PMID:18187979

Altun, Hüseyin; Teker, Ay?enur Meriç; Ceran, Murat; Gedikli, Orhan

2007-01-01

41

Preemptive analgesia in third molar impaction surgery  

PubMed Central

Introduction: We have evaluated efficacy of diclofenac sodium as pre-emptive analgesia agent in a prospective triple blind placebo controlled randomized clinical trial in a patients undergoing third molar impaction surgery. Materials and Methods: Randomization of groups was done by randomization software and two groups were constituted one group receiving placebo pre operatively and then the drug for next five days while the other group was given diclofenac sodium pre operatively and then for five days. Results: Results were achieved with help of measurement of outcome variables like postoperative tenderness, swelling and trismus on a visual analogous scale (VAS) and other personalized scale. Collected data shows that there is a significant reduction in the score of postop tenderness in experimental group (P = 0.00), while there is a minimal difference between score of postoperative swelling and tenderness (P > 0.04). Conclusion: So, we can conclude that use of diclofenac sodium as a preemptive analgesic agent is beneficial for better pain control in third molar impaction surgery.

Shah, Rakesh; Mahajan, Amit; Shah, Navin; Dadhania, Ashish P.

2012-01-01

42

Update on molar pregnancy and choriocarcinoma.  

PubMed

The term gestational trophoblastic disease encompasses a wide spectrum of disorders ranging from the benign hydatidiform mole to the malignant choriocarcinoma and placental site trophoblastic tumor. Recent advances in cytogenetics and pathological criteria have brought to light the occurrence of the partial mole, which is probably more common than the complete mole. The World Health Organisation has proposed a classification to rectify the current confusion that exists with clinical and pathological terms. Evacuation of the uterus followed by meticulous followup with sensitive beta subunit Human Chorionic Gonadotropin assay remain the cornerstone of management of molar pregnancy. Prompt chemotherapy is the most important aspect in managing malignant sequelae. Newer chemotherapy regimes have helped to salvage failures from the usual drugs. Judicial use of surgery in metastatic trophoblastic disease can reduce the duration and toxicity of chemotherapy. All patients with gestational trophoblastic disease should be managed in a tertiary care centre with the expertise and facilities easily available to manage these cases. PMID:2694375

Ilancheran, A; Singh, P

1989-10-01

43

Autotransplantation of Mandibular Third Molar: A Case Report  

PubMed Central

Autogenous transplantation is a feasible, fast, and economical option for the treatment of nonsalvageable teeth when a suitable donor tooth is available. This paper presents successful autotransplantation of a mature mandibular left third molar (38) without anatomical variances is used to replace a mandibular left second molar (37). The mandibular second molar was nonrestorable due to extensive root caries and resorption of distal root. After extraction of mandibular second and third molars, root canal therapy was done for the third molar extraorally, and the tooth was reimplanted into the extracted socket of second molar site. After one year, clinical and radiographic examination revealed satisfactory outcome with no signs or symptoms suggestive of pathology. In selected cases, autogenous tooth transplantation, even after complete root formation of the donor tooth, may be considered as a practical treatment alternative to conventional prosthetic rehabilitation or implant treatment.

Ravi kumar, Pabbati; Jyothi, Mandava; Sirisha, Kantheti; Racca, Khushboo; Uma, Chalasani

2012-01-01

44

Molar mass distribution and solubility modeling of asphaltenes  

SciTech Connect

Attempts to model asphaltene solubility with Scatchard-Hildebrand theory were hampered by uncertainty in molar volume and solubility parameter distribution within the asphaltenes. By considering asphaltenes as a series of polyaromatic hydrocarbons with randomly distributed associated functional groups, molar volume and solubility parameter distributions are calculated from experimental measurements of molar mass and density. The molar mass distribution of Athabasca asphaltenes is determined from interfacial tension and vapor pressure osmometry measurements together with plasma desorption mass spectrometry determinations from the literature. Asphaltene densities are calculated indirectly from mixtures of known concentration of asphaltene in toluene. Asphaltene density, molar volume, and solubility parameter are correlated with molar mass. Solid-liquid equilibrium calculations based on solubility theory and the asphaltene property correlations successfully predict experimental data for both the precipitation point and the amount of precipitated asphaltenes in toluene-hexane solvent mixtures.

Yarranton, H.W.; Masliyah, J.H. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical Engineering

1996-12-01

45

Displacement of maxillary third molar into the lateral pharyngeal space.  

PubMed

Iatrogenic tooth displacement is a rare complication during extraction of impacted molars, but displacement of a maxillary third molar into the maxillary sinus, infratemporal fossa, buccal space, pterygomandibular space, and lateral pharyngeal space has been reported. Currently, 6 published reports describe third molar displacement into the lateral pharyngeal space, only 1 of which involved the loss of a maxillary third molar into this area, which occurred after an attempted self-extraction by the patient. There have been no reported cases of iatrogenic displacement of the maxillary third molar during an extraction procedure. This article describes the recovery, under general anesthesia, of a maxillary third molar from the lateral pharyngeal space after an iatrogenic displacement. PMID:23890786

Lee, Doksa; Ishii, Syoichiro; Yakushiji, Noboru

2013-07-24

46

New perspectives on chimpanzee and human molar crown development  

Microsoft Academic Search

\\u000a Previous histological studies of small samples of chimpanzee and human molars suggested similarities in crown formation time,\\u000a which is surprising given substantial life history differences. As part of an on-going study of hominoid molar development,\\u000a we report on the largest-known sample of chimpanzee and human molars, including re-evaluation of previously examined histological\\u000a sections. Variation of incremental features within and between

T. M. Smith; D. J. Reid; M. C. Dean; A. J. Olejniczak; L. B. Martin

47

Evaluation of an intraoral maxillary molar distalization technique.  

PubMed

The purpose of this study was to determine the effects of the pendulum appliance on distalization of maxillary molars and the reciprocal effects on the anchor premolars and maxillary incisors. Initial and follow-up cephalometric radiographs were obtained on 41 subjects (26 girls and 15 boys) who were treated with the pendulum appliance for bilateral distalization of the maxillary first molar teeth, for correction of the Class II molar relationship or for gaining space in the maxillary arch. Dental casts were available on 31 patients. Dental, skeletal, and soft tissue changes were determined. The mean maxillary first molar distalization was 3.37 mm, with a distal tipping of 8.36 degrees. The mean reciprocal mesial movement of the first premolar was 2.55 mm, with a mesial tipping of 1.29 degrees. The maxillary first molar position intruded 0.1 mm, whereas the first premolar extruded 1.7 mm. The transverse width between the mesiobuccal cusps of the first molars increased 1.40 mm. The maxillary second molars were also distalized 2.27 mm, tipped distally 11.99 degrees, and moved buccally 2.33 mm. The effect of distalization on the maxillary third molars was extremely variable. The eruption of maxillary second molars had minimal effect on distalization of first molars. The lower anterior face height increased by 2.79 mm. This increase was greater in patients with higher Frankfort-mandibular plane angle measurements. The pendulum appliance is an effective and reliable method for distalizing maxillary molars, provided the anchor unit is adequately reinforced. Its major advantages are minimal dependence on patient compliance, ease of fabrication, one-time activation, adjustment of the springs if necessary to correct minor transverse and vertical molar positions, and patient-acceptance. PMID:8972811

Ghosh, J; Nanda, R S

1996-12-01

48

Surface protection for newly erupting first molars.  

PubMed

The objective of this study was to compare the retention of GC Fuji Triage glass-ionomer to Delton FS+, a resin-based sealant on saliva-contaminated enamel surfaces. Seventy-two extracted noncarious human permanent molars were divided into 3 groups for sealing using Triage (T), Delton FS+ with Prime & Bond NT (DP), and Delton FS+ (D) alone. After prophylaxis with pumice, Groups D and DP were etched with 38% H3PO4 for 30 seconds. Group T was treated with Cavity Conditioner. A single drop of natural saliva was applied to the occlusal surface with a microbrush. Sealants were then placed according to the manufacturer's directions. Bonding agent was applied and light-cured for 20 seconds before the application of Delton for the DP group. All sealants covered the entire occlusal surface. The groups were further subdivided into 3 time-evaluation intervals: 6 months, 1 year, and 2 years (8 samples each). They were thermocycled (5 degrees C to 55 degrees C, 1 minute dwell time) at 250, 500, and 1,000 cycles, respectively. After each thermocycling period, they were subjected to toothbrush abrasion for their respective times (3,000 strokes, 6,000 strokes, and 12,000 strokes). All samples were finally observed clinically for retention of sealant. Samples with clinically visible loss of material were further evaluated under a scanning electron microscope (SEM) to verify the loss in the pits and fissures. After the first thermocycling period, 5 of the 24 samples (21%) of Group D revealed complete visual loss of sealant. There was no further loss after the second period. After the third period of thermocycling, an additional 4 samples revealed complete visible loss of the sealant material from Group D (total 37.5% failure). SEM evaluation verified the complete loss of sealants. Groups T and DP showed 100% retention after the entire period of aging and toothbrush-abrasion. Both of these groups demonstrated similar wear rates. Therefore, concerning fluoride release and simpler technique, especially with newly-erupting molars, Triage has advantages. PMID:16454015

Antonson, Sibel A; Wanuck, Jason; Antonson, Donald E

2006-01-01

49

Sensory nerve impairment following mandibular third molar surgery  

Microsoft Academic Search

Purpose: This prospective study reports the rate and factors influencing sensory impairment of the inferior alveolar and lingual nerves after the removal of impacted mandibular third molars under local anesthesia. Patients and Methods: There were 741 patients with 741 mandibular third molars removed under local anesthesia during a 3-year period from 1994 to 1997. Standardized data collection included the patient's

Anwar B Bataineh

2001-01-01

50

Molar Intercuspal Dimensions: Genetic Input to Phenotypic Variation  

Microsoft Academic Search

Molecular studies indicate that epigenetic events are important in determining how the internal enamel epithelium folds during odontogenesis. Since this process of folding leads to the subsequent arrangement of cusps on molar teeth, we hypothesized that intercuspal distances of human molar teeth would display greater phenotypic variation but lower heritabilities than overall crown diameters. Intercuspal distances and maximum crown diameters

G. Townsend; L. Richards; T. Hughes

2003-01-01

51

Molecular Characterization of Human Impacted Third Molars: Diversification of Compartments  

Microsoft Academic Search

To gain more insight into the development of human teeth, we characterized different compartments of impacted third molars at two developmental stages by assessing expression levels of a set of genes. We considered genes known to be essential for the development of teeth and ectomesenchyme as well as genes covering characteristic features of stemness. Molars were divided into the operculum,

B. Schoenebeck; H. J. Hartschen; M. Schindel; O. Degistirici; J. Siemonsmeier; W. Goetz; M. Thie

2009-01-01

52

Orthodontic band retention on primary molar stainless steel crowns  

Microsoft Academic Search

The retention of orthodontic bands cemented on primary molar stainless steel crowns (SSC) was studied in vitro. Unitek maxillary and mandibular 1st and 2nd primary molar SSC were fitted with one of four commonly used orthodontic bands (Unitek regular, Unitek narrow, Rocky Mountain, or custom bands made from SSC) using glass ionomer cement. The cemented samples were tested for their

Randy L. Beemer; Jack L. Ferracane; Harold E. Howard

1993-01-01

53

Root canal morphology of human maxillary and mandibular third molars.  

PubMed

The anatomy of third molars has been described as unpredictable. However restorative, prosthetic, and orthodontic considerations often require endodontic treatment of third molars in order for them to be retained as functional components of the dental arch. The purpose of this study was to investigate and characterize the anatomy of maxillary and mandibular third molars. One hundred fifty maxillary and 150 mandibular extracted third molars were vacuum-injected with dye, decalcified, and made transparent. The anatomy of the root canal system was then recorded. Seventeen percent of mandibular molars had one root (40% of which contained two canals), 77% had two roots, 5% had three roots, and 1% had four roots. Teeth with two roots exhibited highly variable canal morphology, containing from one to six canals, including 2.2% that were "C-shaped." Fifteen percent of maxillary molars had one root, 32% had two roots, 45% had three roots, and 7% had four roots. Teeth with one root demonstrated the most unusual morphology, with the number of canals varying from one to six. An in vivo study of the canal morphology of treated third molars is suggested to provide the practitioner with an understanding of the clinical implications of third molar root anatomy. PMID:11469300

Sidow, S J; West, L A; Liewehr, F R; Loushine, R J

2000-11-01

54

Analysis of rapid maxillary molar distal movement without patient cooperation  

Microsoft Academic Search

The purpose of this investigation was to evaluate the treatment effects of an intraoral appliance used for rapid distal movement of the maxillary molars. The appliance studied, the Jones jig, is designed to deliver a distalizing force to the maxillary molar against an intraoral anchorage unit thereby eliminating the need for patient compliance. A retrospective study was performed comparing before

Mark E. Runge; John T. Martin; Firas Bukai

1999-01-01

55

Relative molar response factors for thermal conductivity detectors  

PubMed

This paper describes an investigation into the universal nature of relative molar response factors for thermal conductivity detectors. Relative molar response factors are measured on multiple gas chromatographs equipped with thermal conductivity detectors, and the values are compared with values in the literature. As was observed previously, relative molar responses obtained on a single instrument for a homologous series vary linearly with respect to the number of carbon atoms in the hydrocarbon chain. However, significant differences are observed for the slope of this line depending on the instrument studied. This contradicts previous literature results that demonstrated an indepedence of the relative molar response with regard to the detector. The current results show that the calibration of thermal conductivity detectors using literature values for relative molar response factors could produce significant errors in the concentrations measured by the laboratory chromatograph. PMID:10702921

Gislason; Wharry

2000-03-01

56

Extraction of maxillary first molars improves second and third molar inclinations in Class II Division 1 malocclusion  

Microsoft Academic Search

INTRODUCTION: The aim of this study was to assess the changes in inclination of the maxillary second (M2) and third (M3) molars after orthodontic treatment of Class II Division 1 malocclusion with extraction of maxillary first molars. METHODS: Two groups of subjects were studied. The experimental group consisted of 37 subjects, 18 boys and 19 girls (mean age, 13.2 +\\/-

Christos Livas; Demetrios J. Halazonetis; Johan Willem Booij; Christos Katsaros

2011-01-01

57

Are referred inaccessible human primary molar teeth really inaccessible?  

PubMed

Despite a body of compelling evidence pertaining to the root canal accessibility of primary teeth, the number of referrals for inaccessibility of primary molars is considerable. The aim of the present study was to evaluate the prevalence of true and false primary molar inaccessibility among subjects who had been referred by general and pediatric dentists. We examined 199 primary molars in 156 patients (87 males, 69 females) aged 3-7 years who were referred by 215 general and 35 pediatric dentists. Problems related to inaccessibility were recorded for each tooth and any individual canal. One hundred seventy-five inaccessible teeth (87.9%) were successfully rehabilitated to accessible status (P < 0.001). The most frequent cause of inaccessibility was an inappropriate access cavity (42.3%), followed by difficult canals (32.6%) and orifice calcification (25.2%). The tooth most frequently reported as inaccessible was the maxillary first molar (40.2%), and that least frequently reported was the mandibular second molar (11.6%). The distobuccal canal of the maxillary first molar and the mesiolingual canal of the mandibular first molar were the most commonly inaccessible canals (P < 0.001). Only 1 out of 8 teeth referred as inaccessible was truly inaccessible. It seems that root canal inaccessibility is mostly attributable to lack of expertise among individual practitioners. PMID:23748457

Asl Aminabadi, Naser; Sighari Deljavan, Alireza; Samiei, Mohammad; Jamali, Zahra

2013-01-01

58

Maize and oat antixenosis and antibiosis against Delphacodes kuscheli (Homoptera: Delphacidae), vector of "Mal de Rio Cuarto" of maize in Argentina.  

PubMed

"Mal de Rio Cuarto" (MRC) is the most important virus disease of maize, Zea mays L., in Argentina. Several maize lines show different levels of resistance to MRC in the field; however, no studies have been conducted to investigate resistance mechanisms against its insect vector, Delphacodes kuscheli Fennah (Homoptera: Delphacidae). Oat, Avena spp., is the main overwintering host of D. kuscheli and main source of populations that infest maize. Although oat varieties resistant to the greenbug, Schizaphis graminum (Rondani) (Homoptera: Aphididae) are commercially available, their effect on D. kuscheli is unknown. We conducted laboratory experiments to test for the presence of antixenosis and antibiosis resistance mechanisms on six maize lines with different levels of field resistance to MRC, and seven commercial oat cultivars that include two S. graminum-resistant varieties. We did not find antibiotic effects of maize lines on D. kuscheli longevity and survivorship patterns, but we obtained antixenotic effects from the LP2 line (field moderate) due to reduced settling preference and feeding. Oat 'Bonaerense Payé and 'Suregrain INTA' showed both antixenosis and antibiosis, with significantly less settling preference, oviposition in the no-choice test, and reduced total fecundity in comparison with the other varieties studied. The S. graminum-resistant 'Boyera F. A.' and 'Tambera F. A.' did not showed a consistent pattern of resistance versus D. kuscheli across all experiments. Our results indicate the presence of potential sources of insect resistance in the maize lines and oat cultivars tested that may be used in MRC integrated pest management programs. PMID:16156593

Costamagna, A C; de Remes Lenicov, A M M; Zanelli, M

2005-08-01

59

Fifth alternative for replacement of maxillary first molar.  

PubMed

There are occasions when the patient is missing only one first molar or the first molar is slated for an odontectomy (extraction). Most of the time, there are only four common avenues for replacement: partial removable prosthesis, Maryland bridge, ceramic or ceramic to metal fixed prosthesis and osseo-integrated implant supported crown. In this article, the author discusses the least common avenue for replacement of missing maxillary first molar--an orthodontic closure. He discusses and demonstrates; Maximum, Medium and Minimum Anchorage strategies on acrylic models. Preserving the anchorage is necessary for successful execution of this orthodontic procedure. This demonstration is followed by presentation of the actual case. PMID:23941033

Palencar, Adrian J

2013-01-01

60

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

61

Impaction of First Permanent Molars-Case Report.  

National Technical Information Service (NTIS)

Occasionally, the extraction of an impacted tooth provides a clinical challenge for an oral surgeon. Any tooth may be impacted, but third molars and maxillary cuspids are most frequently encountered followed by premolars and supernumerary teeth. Various s...

P. S. Grover L. Lorton

1982-01-01

62

Endodontic management of middle mesial canal of the mandibular molar.  

PubMed

Thorough knowledge of root canal morphology and unusual anatomy of the tooth is critical for successful endodontic treatment. Although the most common configuration is two roots and three root canals, mandibular molars might have many different combinations. In the literature, it is less described about three mesial canals and two distal canals in mandibular second molars, indicating a rare anatomical configuration. A case of unusual root canal morphology is presented to demonstrate anatomical variations in mandibular molars. Endodontic therapy was performed in a mandibular second molar with five separate canals, three mesial and two distal. This report points out the importance of looking for additional canals and unusual canal morphology, because knowledge of their existence might occasionally enable clinicians to treat a case successfully that otherwise might have ended in failure. In conclusion, every attempt should be made to find and treat all root canals of a tooth. PMID:23349182

Sundaresh, K J; Srinivasan, Raghu; Mallikarjuna, Rachappa; Rajalbandi, Sandeep

2013-01-23

63

Determining Molar Combining Ratios Using Radioisotopes--A Student Experiment  

ERIC Educational Resources Information Center

|Outlines an experimental procedure in which an iodine radioisotope is used to determine molar combining ratios of lead and silver with the iodine. Tables and graphs show the definitive results that should be attainable. (CP)|

Sears, Jerry A.

1976-01-01

64

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

Code of Federal Regulations, 2010 CFR

...false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section...642 SSV, CFV, and PDP molar flow rate calculations. This section describes...the equations for calculating molar flow rates from various flow meters....

2010-07-01

65

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

Code of Federal Regulations, 2013 CFR

...false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section...642 SSV, CFV, and PDP molar flow rate calculations. This section describes...the equations for calculating molar flow rates from various flow meters....

2013-07-01

66

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

Code of Federal Regulations, 2010 CFR

...false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section...642 SSV, CFV, and PDP molar flow rate calculations. This section describes...the equations for calculating molar flow rates from various flow meters....

2009-07-01

67

Maxillary first permanent molar impaction. A conservative treatment approach.  

PubMed

The objective of this clinical case is to suggest a treatment approach for impaction of the maxillary first permanent molars. This approach allows access to the partially erupted tooth for orthodontic bonding and utilization of loops for distalization. An important detail is the non inclusion of the primary second molar in the orthodontic mechanics, in order to reduce the risk of early loss and preserve this tooth until exfoliation. PMID:16491975

Rizzatto, Susana Maria Deon; de Menezes, Luciane Macedo; do Rego, Marcus Vinicius Neiva Nunes; Thiesen, Guilherme; de Araujo, Vanessa Pereira; Freitas, Maria Perpétua Mota

2005-01-01

68

The effect of maxillary molar distalization on cervical posture  

Microsoft Academic Search

Summary  PURPOSE: The objectives of this study were to determine whether maxillary molar distalization with a Pendulum appliance affects\\u000a the cervical posture, and whether lateral cephalometry can measure these changes. METHODS: Twenty Dental Class II subjects,\\u000a aged 11.5–15.5, were selected for maxillary molar distalization with a Pendulum appliance. Before treatment, a lateral cephalogram\\u000a was recorded in natural head position. The lateral

P. Currie; S. Lobo-Lob; P. Stark; N. Mehta

2009-01-01

69

Nanomechanical Behavior of Human Molars Soaked in Slight Acid Solutions  

Microsoft Academic Search

This paper studied the mechanical and chemical properties of hydroxyl apatite (HA) crystal structure in the teeth when human molars were soaked in slight acid solution. First, we soaked the ground and polished molars respectively in the liquor of 30 wt.% H2CO3 and the liquor of 30 wt.% H2O2 for 10, 20, or 60 minutes. Next, we used a nanoindenter

Te-Hua Fang; Win-Jin Chang; Shao-Hui Kang; Chia-Chun Chu

2009-01-01

70

Preliminary Evaluation of Sodium Hypochlorite for Pulpotomies in Primary Molars  

Microsoft Academic Search

Purpose: The purpose of this study was to compare the effectiveness of 5% sodium hypo- chlorite (NaOCl) to that of ferric sulfate (FeSO4) as a pulpotomy medicament in decayed primary molars. Methods: Healthy subjects between 4 and 9 years with at least 2 primary molars need- ing pulpotomy consented to receive either NaOCl or FeSO4 and restoration with IRM base\\/stainless

Kaaren G. Vargas; Brett Packham; David Lowman

2006-01-01

71

Partial molar quantity of an intensive mother function  

NASA Astrophysics Data System (ADS)

A new formal definition is given to the partial molar quantity of a component i for an intensive mother function. We perturb the entire system by increasing the amount of the target component by ?ni keeping others constant and measure the response of the system in terms of an intensive mother function, ?, ??. We then define its partial molar quantity of the ith component, ?i, as ?i = [??/{?ni/(N + ?ni)

Koga, Yoshikata

2012-09-01

72

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.

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

2010-01-01

73

Thiomers: influence of molar mass on in situ gelling properties.  

PubMed

The aim of this study was to investigate the influence of molar mass of thiolated polymers (thiomers) on their in situ gelling properties. Chitosan-thioglycolic acid (chitosan-TGA) and pectin-cysteine (pectin-Cys) of increasing molar mass were chosen to produce in situ gels in combination with carbamide peroxide. Low molar mass chitosan (~2 kDa) was prepared by oxidative degradation with NaNO(2), whereas pectin was depolymerized by heat treatment. Thiomers, displaying 1271-1616 ?mol (chitosan-TGA) and 305-403 ?mol (pectin-Cys) free thiol groups per gram polymer, were synthesized via amide bond formation mediated by a carbodiimide. The results showed that a reduction of molar mass combined with increased concentrations of both cationic chitosan-TGA and anionic pectin-Cys leads to higher final viscosities and to a higher relative increase in viscosity within 60 min and 180 min, respectively. Using this method, the dynamic viscosity of a very low molar mass chitosan-TGA (~2 kDa) could be increased 100,000-fold within 60 min and 390,000-fold within 180 min. In view of these in situ gelling properties carbohydrate thiomers might be useful for various pharmaceutical applications such as vehicle for drug delivery or as wound dressing material. PMID:22683454

Hintzen, Fabian; Laffleur, Flavia; Sarti, Federica; Shahnaz, Gul; Bernkop-Schnürch, Andreas

2012-06-07

74

Dental Treatment Needs of Permanent First Molars in Mashhad Schoolchildren  

PubMed Central

Background and aims In spite of their enormous importance, permanent first molars might be affected by caries in children in developing countries. The aim of this study was to evaluate the treatment needs of first permanent molars in a group of schoolchildren in Mashhad. Materials and methods This cross-sectional descriptive study was carried out on 700, 7-9 year-old students in primary schools in Mashhad. The schools were randomly selected from each district. Treatment needs and DMFT of first perma-nent molars were calculated. Data was analyzed using ANOVA, Chi-Square and t-test. Results A total of 95.3% of the children required dental treatment. Fissure sealant application and filling were the treat-ments most required in all age groups. The mean DMFT of first permanent molars was 1.31±1.4. It was significantly higher in girls than boys (P=0.040). Conclusion Great treatment needs and caries prevalence in permanent first molars in Mashhad schoolchildren show that dental caries is still a serious problem in the children of our society; therefore, education of parents and teachers is necessary for promoting children's oral health.

Ebrahimi, Masoumeh; Ajami, Behjat-Al-Molook; Sarraf Shirazi, Ali Reza; Afzal Aghaee, Monavar; Rashidi, Somayeh

2010-01-01

75

Requirement of alveolar bone formation for eruption of rat molars  

PubMed Central

Tooth eruption is a localized event that requires a dental follicle (DF) to regulate the resorption of alveolar bone to form an eruption pathway. During the intra-osseous phase of eruption, the tooth moves through this pathway. The mechanism or motive force that propels the tooth through this pathway is controversial but many studies have shown that alveolar bone growth at the base of the crypt occurs during eruption. To determine if this bone growth (osteogenesis) was causal, experiments were designed in which the expression of an osteogenic gene in the DF, bone morphogenetic protein-6 (BMP6), was inhibited by injection of the 1st mandibular molar of the rat with an siRNA targeted against BMP6. The injection was followed by electroporation to promote uptake of the siRNA. In 45 first molars injected, eruption either was delayed or completely inhibited (7 molars). In the impacted molars, an eruption pathway formed but bone growth at the base of the crypt was greatly reduced as compared to the erupted first molar controls. These studies show that alveolar bone growth at the base of the crypt is required for tooth eruption and that BMP6 may be an essential gene for promoting this growth.

Wise, Gary E.; He, Hongzhi; Gutierrez, Dina L.; Ring, Sherry; Yao, Shaomian

2011-01-01

76

Sonographic 'molar tooth' sign in the diagnosis of Joubert syndrome.  

PubMed

The characteristic imaging finding common to Joubert syndrome and related disorders is the 'molar tooth' sign. The prenatal diagnosis of Joubert syndrome using both ultrasound and fetal magnetic resonance imaging (MRI) in families with an affected child has been reported previously. We report two cases in which the molar tooth sign was identified by sonography at 26 + 4 weeks and at 20 + 6 weeks, respectively, prior to fetal MRI or genetic testing. In both cases the finding was subsequently confirmed on fetal MRI. As definitive prenatal genetic testing may not be conclusive in Joubert syndrome, the ability to identify the molar tooth sign sonographically before 24 weeks provides a valuable adjunct to prenatal diagnosis. PMID:21370303

Pugash, D; Oh, T; Godwin, K; Robinson, A J; Byrne, A; Van Allen, M I; Osiovich, H

2011-11-01

77

Use of sevoflurane inhalation sedation for outpatient third molar surgery.  

PubMed Central

This study attempted to determine if sevoflurane in oxygen inhaled via a nasal hood as a sole sedative agent would provide an appropriate level of deep sedation for outpatient third molar surgery. Twenty-four patients scheduled for third molar removal were randomly assigned to receive either nasal hood inhalation sevoflurane or an intravenous deep sedation using midazolam and fentanyl followed by a propofol infusion. In addition to measuring patient, surgeon, and dentist anesthesiologist subjective satisfaction with the technique, physiological parameters, amnesia, and psychomotor recovery were also assessed. No statistically significant difference was found between the sevoflurane and midazolam-fentanyl-propofol sedative groups in physiological parameters, degree of amnesia, reported quality of sedation, or patient willingness to again undergo a similar deep sedation. A trend toward earlier recovery in the sevoflurane group was identified. Sevoflurane can be successfully employed as a deep sedative rather than a general anesthetic for extraction of third molars in healthy subjects.

Ganzberg, S.; Weaver, J.; Beck, F. M.; McCaffrey, G.

1999-01-01

78

Aberration in the palatal root of the maxillary first molar.  

PubMed

Thorough knowledge of root canal morphology is essential for the endodontic therapy. Variations in the root and root canal morphology, especially in multirooted teeth, are a constant challenge for diagnosis and management. The dentist needs to be familiar with the various root canal configurations and their variations for successful endodontic therapy. There are rare variations in canal number and configuration in maxillary molars, which could affect treatment outcome. Two lingual root structures are occasionally found on human permanent maxillary molars. One of these is the normal lingual root, which is always present, the other is a supernumerary structure which can be located either mesiolingually (radix mesiolingualis) or distolingually (radix distolingualis). The purpose of this paper is to review the literature and to demonstrate a case report which describes the successful non-surgical endodontic management of an unusual maxillary first molar with four separate roots and four canals. PMID:23632609

Rajalbandi, Sandeep; Shingte, Sandhya Narayan; Sundaresh, K J; Mallikarjuna, Rachappa

2013-04-30

79

Paramolar - A supernumerary molar: A case report and an overview  

PubMed Central

Paramolar is a supernumerary molar usually small and rudimentary, most commonly situated buccally or palatally to one of the maxillary molars. Paramolar is a developmental anomaly and has been argued to arise from a combination of genetic and environmental factors. Reports of this entity are rarely found in the dental literature. This article presents a case report of an unusual occurrence of a paramolar in the maxilla in otherwise a healthy individual. In addition, literature review, prevalence, classification, etiology, complications, diagnosis, and therapeutic strategies that may be adopted when supernumeraries occurs have been discussed.

Nayak, Gurudutt; Shetty, Shashit; Singh, Inderpreet; Pitalia, Deepti

2012-01-01

80

Surveillance without chemotherapy in a woman with recurrent molar pregnancy.  

PubMed

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

2013-02-20

81

3D reconstruction of two C-shape mandibular molars.  

PubMed

Two mandibular second molars, with an indication of C-shape morphology were processed for 3-D reconstruction. After serial cross sectioning, photographs of the sections were digitized and by using surface representation, 3D reconstruction was achieved. The first molar as the 3D reconstruction showed was single rooted with one C-shaped root canal with two foramens, while the second one was double rooted with two root canals, one C-shaped and one thin, having a common foramen. PMID:9220739

Lyroudia, K; Samakovitis, G; Pitas, I; Lambrianidis, T; Molyvdas, I; Mikrogeorgis, G

1997-02-01

82

DFT-based quantum theory QSPR studies of molar heat capacity and molar polarization of vinyl polymers  

Microsoft Academic Search

In this study, the DFT\\/B3LYP level of theory with the 6-31G (d) basis set was used to calculate a set of quantum chemical\\u000a descriptors for structure units of vinyl polymers. These descriptors were used to predict the molar heat capacity of “liquid”\\u000a at constant pressure (C\\u000a \\u000a P\\u000a 1(298 K)) and the molar Lorentz and Lorenz polarization (P\\u000a LL). Two more

Xinliang Yu; Bing Yi; Wenhao Yu; Xueye Wang

2008-01-01

83

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?

84

A Novel Mutation in Human PAX9 Causes Molar Oligodontia  

Microsoft Academic Search

Experimental and animal studies, as well as genetic mutations in man, have indicated that the development of dentition is under the control of several genes. So far, mutations in MSX1 and PAX9 have been associated with dominantly inherited forms of human tooth agenesis that mainly involve posterior teeth. We identified a large kindred with several individuals affected with molar oligodontia

S. A. Frazier-Bowers; D. C. Guo; A. Cavender; L. Xue; B. Evans; T. King; D. Milewicz; R. N. DSouza

2002-01-01

85

Thickness Measurement of Worn Molar Cusps by Ultrasound  

Microsoft Academic Search

This study aimed to evaluate the effectiveness of an ultrasonic system for in vitro measurement of cusp tips of human teeth. Each worn cusp of 12 molar teeth was measured with an industrial ultrasonic system. The teeth were sectioned and measured by polarized light microscopy. The ultrasonic measurements and histological readings were moderately correlated (r = 0.601, p < 0.01).

D. Arslantunali Tagtekin; F. Öztürk; M. Lagerweij; O. Hayran; G. K. Stookey; F. Çaliskan Yanikoglu

2005-01-01

86

Maxillary right second molar with two palatal root canals  

PubMed Central

We report a clinical case of maxillary right second molar with two palatal root canals. The morphology is atypical because it is characterized by two palatal roots with two canals with widely separated orifices and canals. Modifications to the normal access opening and examination of the pulpal floor for additional canals are stressed.

Prashanth, M B; Jain, Pradeep; Patni, Pallav

2010-01-01

87

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

88

Hemisection as an alternative treatment for vertically fractured mandibular molars.  

PubMed

Hemisection of mandibular molars may be a viable treatment option when vertical root fracture has occurred and the other root is healthy. This article discusses a case that presents the techniques involved in hemisection and restoration of the remaining tooth root. PMID:16494100

Kurtzman, Gregori M; Silverstein, Lee H; Shatz, Peter C

2006-02-01

89

Excess Molar Polarization in Binary Mixtures of Polar Liquids  

Microsoft Academic Search

Excess Molar Polarizations (?PW.Q., ?PD.D.) have been evaluated in the binary mixture of associated + associated and associated + nonassociated polar liquids using Winkelmann-Quitzsch and Davis-Douheret equations. It is observed that Winkelmann-Quitzsch equation ?PW.Q. is the more appropriate one for interpretation of dynamic characteristics of the molecular association in a liquid mixture.

S. K. Ray; J. Rath; C. Dwivedi

2001-01-01

90

Patent Accessory Canals: Incidence in Molar Furcation Region.  

National Technical Information Service (NTIS)

A total of 46 extracted maxillary and mandibular molars were examined to determine the incidence of accessory canals in the coronal and middle third of the root surface. A radiopaque dye was drawn through the root canal system under a vacuum of 5 p.s.i., ...

J. V. Lowman R. S. Burke G. B. Pelleu

1974-01-01

91

Impaction of permanent mandibular second molar: A retrospective study  

PubMed Central

Objective: To determine the prevalence of impacted mandibular second molar (MM2) and the association between MM2 impaction and crowding. The clinical significance of the angle between first and second mandibular molar and of the space between the first mandibular molar (MM1) and the anterior margin of mandibular ramus in MM2 impaction were also evaluated. Material and Methods: In this retrospective study , from the dental records of 2,945 caucasian young orthodontics patients, 40 subjects with MM2 impaction were included in a study group (SG) and compared with a control group (CG) of 200 subjects without MM2 impactions. The crowding, the angle of inclination of MM2, the distance between MM1 and mandibular ramus, the canine and molar relationships, and the lower centre line discrepancy were measured. For the statistical analysis , descriptive statistics and t-Student for independent sample groups were used. Results: The prevalence of impacted MM2 was 1.36%. The independent-Samples t-Test between SG and CG showed: the presence of crowding (P?0.001), an higher angle values of MM2 inclination (P?0.001) and a smaller distance between MM1 and the anterior margin of mandibular ramus (P?0.001) in the SG. Conclusion: The impaction of MM2 is a relatively rare occurrence in orthodontic caucasian populations. The crowding, a higher angle values of MM2 inclination and a reduced distance between MM1 and the anterior margin of mandibular ramus, at the time of one third of MM2 root formation (T1), characterize MM2 impaction. Key words:Impacted mandibular second molar, impaction, orthodontics.

Altieri, Federica; Di Mambro, Alfonso; Galluccio, Gabriella; Barbato, Ersilia

2013-01-01

92

Partial Molar Volumes for Lanthanide Sesquioxides in Sodium Silicate Melts  

NASA Astrophysics Data System (ADS)

Lanthanides are of great interest in igneous petrology as trace indicators of magmatic processes that control the origin and evolution of igneous rocks. A key to the petrogenetic modelling of magmatic processes and to determine the phase diagrams of lanthanide host phases is the accurate determination of the physico-chemical and thermodynamic properties of lanthanide-containing materials, such as the volumetric properties of lanthanide-bearing silicate melts. Therefore, we have undertaken to provide a new reliable volumetric data set for lanthanide-bearing silicate melts which allows the available models in the literature to be extended to lanthanide-bearing melts. For this purpose, the densities of various lanthanide-bearing silicate melts distributed along various pseudo-binary joins, where the end-members are Na-disilicate and one of the lanthanide sesquioxides (i.e., Ce2O3, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3 and Yb2O3), have been measured using the double-bob Archimedean method. The present results show that the addition of any lanthanide to Na-disilicate leads to an increase in the melt density and that the melt density increases with increasing atomic number of the lanthanide. From the present density data set, the molar volumes of these melts have been calculated and the partial molar volumes of each lanthanide sesquioxide in these melts have been determined using a linear regression through each pseudo-binary join (i.e., Na-disilicate - lanthanide sesquioxide). This study indicates ideal behaviour with respect to the molar volume (i.e., a linear variation of the molar volume along each pseudo-binary join) for Na-silicate melts containing up to 10 mol% of lanthanide oxide. Comparison between the partial molar volumes of lanthanide sesquioxides obtained in this study and the molar volumes of molten lanthanide sesquioxides given in the literature raise the possibility however that this ideality is not maintained along the entire Na-disilicate - lanthanide sesquioxide pseudo-binary joins. Excess volumes of mixing appear to be required to describe the combined volumetric data set.

Courtial, P.; Dingwell, D. B.

2004-12-01

93

Molar volumes of aqueous and ethylene glycol solutions of tetrahydrofuran  

NASA Astrophysics Data System (ADS)

The densities of ethylene glycol solutions of tetrahydrofuran (THF) with 0-20 mol % THF were measured at 20-60°C and atmospheric pressure to an accuracy of 5 × 10-5 g/cm3. The apparent molar volumes of THF in the solutions were calculated and their concentration and temperature dependences determined. The results were compared with the apparent molar volumes of THF in aqueous systems calculated from the literature data. Minima were found on the concentration dependence of the apparent volume of THF for both aqueous and ethylene glycol solutions and changed differently as the temperature increased. The data obtained were discussed from the standpoint of solvophobic effects in aqueous and ethylene glycol solutions of THF.

Rodnikova, M. N.; Gunina, M. A.; Makarov, D. M.; Egorov, G. I.; Val'Kovskaya, T. M.

2011-09-01

94

Thermal correction to the molar polarizability of a Boltzmann gas  

SciTech Connect

Metrology in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very precise frequency measurements, the molar polarizability of an atomic gas has recently also been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Units (SI), for which an accurate value of the Boltzmann constant is needed. Here we calculate the dominant shift of the molar polarizability in an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when the probing electric field is Lorentz transformed into the rest frame of the atoms that undergo thermal motion. While this effect is small when compared to currently available experimental accuracy, the relativistic correction to the dipole interaction is much larger than the thermal shift of the polarizability induced by blackbody radiation.

Jentschura, U. D. [Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409-0640 (United States); Puchalski, M. [Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409-0640 (United States); Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL-60-780 Poznan (Poland); Mohr, P. J. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8420 (United States)

2011-12-15

95

"C"-shaped canal configuration of mandibular second permanent molar.  

PubMed

Roots of the second mandibular molar often fuse so the purpose of this investigation was to examine the appearance of "C"-shaped root canals and to classify different root canal types. A hundred and twelve randomly chosen second lower permanent molars-after extraction due to periodontal disease-were prepared and then analysed. Contrast liquid (methylene blue) was injected into prepared teeth. Each tooth was cut into slices to view the root canal morphology. Results of the analysis revealed fusion, either total or partial in 14 cases (12.5%). As a conclusion various appearances were classified into 5 types according to the fused canal shapes and the frequency of different types varied from 0.89%-6.25%. PMID:10097434

Sutalo, J; Simeon, P; Tarle, Z; Prskalo, K; Pevalek, J; Stanici?, T; Udovici?, M

1998-06-01

96

Better outcomes in pulpotomies on primary molars with MTA  

Microsoft Academic Search

Data sourcesMedline, Cochrane Library, Embase, Science Citation Index and the China National Knowledge Infrastructure were used to source articles. In addition, identified papers' reference lists and their authors' other published literature were also scanned.Study selectionStudies of interest were randomised controlled trials of primary molar teeth where there was exposure of vital pulp caused by caries or trauma, with at least

Nicola Innes

2007-01-01

97

Rats’ responses to molar and local schedule constraints  

Microsoft Academic Search

Three experiments explored responses to molar and local schedule constraints. Thirsty rats pressed a lever for access to a\\u000a water spout. In Experiment 1, response totals were unaffected by two local schedule characteristics—the variability of the\\u000a instrumental requirement and the variability of the magnitude of contingent reward. Experiment 2 manipulated the correlation\\u000a between the instrumental requirement and the magnitude of

James Allison; Alison Buxton; Kevin E. Moore

1987-01-01

98

Foreign bodies in primary molars: a report of 2 cases.  

PubMed

Foreign bodies can be found in the pulps of primary teeth during routine oral examinations. These foreign bodies can result in painful complications. A detailed case history and clinical and radiographic examinations are necessary to come to a conclusion about the nature, size, and location of the foreign body, and to determine the difficulty involved in its removal. The purpose of this paper was to discuss 2 clinical cases and the management of foreign bodies found lodged in primary molars. PMID:22449509

Gujjar, Kumar Raghav; Algali, Ghazala; Omar, Suleiman M; Amith, H V; Anegundi, Rajesh T

99

Radicular Cyst in Deciduous Maxillary Molars: A Rarity  

PubMed Central

Radicular cyst arising from deciduous teeth is exceedingly rare accounting for <1% of all radicular cysts. A total of 122 cases have been reported to date in the English language literature. We present a rare case of a radicular cyst associated with a decayed deciduous maxillary molar tooth without any history of prior pulp therapy. Our aim is to emphasize the recognition of inflammatory radicular lesions associated with deciduous teeth which may adversely impact underlying permanent successor.

Shetty, Shibani; Rekha, K.

2009-01-01

100

Dentigerous Cyst Associated with a Formocresol Pulpotomized Deciduous Molar  

Microsoft Academic Search

This report presents a case of dentigerous cyst associated with a formocresol pulpotomized deciduous molar detected during routine examination. Dentigerous cyst is an epithelial-lined developmental cavity that encloses the crown of an unerupted tooth at the cementoenamel junction. The present case describes a 9-year-old girl sent to the dental clinic by her dentist, who had accidentally discovered in the panoramic

Manuela Pereira-Maestre; Dolores Conde-Fernández; Ignacio Vilchez; Juan José Segura-Egea; José Luis Gutiérrez-Pérez

2007-01-01

101

Determination of molar mass polydispersity index from dynamic rheological measurements  

Microsoft Academic Search

The polydispersity of the molar mass of a material influences the behaviour of its dynamic rheological propertiesG' (?) andG? (?). This is exemplified by the deviation from unity of the indexI = [2 - (d logG'\\/d log?)]\\/[1 - (d logG?\\/d log?)] in the terminal zone, i.e. at low frequencies. For a normal logarithmic distribution of species, a quantitative correlation may

G. Couarraze; J. L. Grossiord; F. Puisieux

1986-01-01

102

Third molars may have a negative impact on periodontal health  

Microsoft Academic Search

DesignThis was a cross-sectional study.Materials and methodsData were within a cohort study obtained between 1996 and 1999 on 6793 people of 52–74 years of age from the dental substudy of the Atherosclerosis Risk in Communities Study. The main independent variable was presence or absence of third molars, assessed visually, and the dependent variable was assessment of periodontal disease designated by

Graham J Smart

2005-01-01

103

Morphogenesis and bone integration of the mouse mandibular third molar.  

PubMed

The mouse third molar (M3) develops postnatally and is thus a unique model for studying the integration of a non-mineralized tooth with mineralized bone. This study assessed the morphogenesis of the mouse M3, related to the alveolar bone, comparing M3 development with that of the first molar (M1), the most common model in odontogenesis. The mandibular M3 was evaluated from initiation to eruption by morphology and by assessing patterns of proliferation, apoptosis, osteoclast distribution, and gene expression. Three-dimensional reconstruction and explant cultures were also used. Initiation of M3 occurred perinatally, as an extension of the second molar (M2) which grew into a region of soft mesenchymal tissue above the M2, still far away from the alveolar bone. The bone-free M3 bud gradually became encapsulated by bone at the cap stage at postnatal day 3. Osteoclasts were first visible at postnatal day 4 when the M3 came into close contact with the bone. The number of osteoclasts increased from postnatal day 8 to postnatal day 12 to form a space for the growing tooth. The M3 had erupted by postnatal day 26. The M3, although smaller than the M1, passed through the same developmental stages over a similar time span but showed differences in initiation and in the timing of bone encapsulation. PMID:21726286

Chlastakova, Ivana; Lungova, Vlasta; Wells, Kirsty; Tucker, Abigail S; Radlanski, Ralf J; Misek, Ivan; Matalova, Eva

2011-08-01

104

Characteristics of 351 supernumerary molar teeth In Turkish population  

PubMed Central

Objective: The aim of the present study was to evaluate the demographic profile of supernumerary molar (SM) teeth in people in various regions of Turkey. Study Design: A retrospective analysis was carried out on an initial sample of 104,902 subjects drawn from the ortopantographics files from 10 clinics in 7 Turkish cities with documentation of demographic data, the presence of SM teeth, their location, eruption, morphology, and position within the arch. In one region associated patho­logies and treatments were also evaluated. Results: Three hundred fifty-one SMs were detected in 288 patients, constituting 0.33% of the study subjects, with a greater frequency in females (56.4%). SMs were found more frequently in the maxilla (87.7%) than in the mandible, and distomolars (62.9%) were more common than paramolars. The SMs encountered were mostly of conical shape (45.7%), impacted (81.1%), and in a vertical position (52.1). The 33% of SM teeth were related to impacted molar teeth. Conclusion: The most common complication involving these teeth was soft tissue irritation. Demographic data from such specific extensive studies are crucial for improved diagnosis of SM teeth. Early detection allows for measures against complications and more successful therapy. Key words:Supernumerary molars, distomolar, paramolar, prevalence.

Kara, Muhammed I.; Ay, Sinan; Bereket, Cihan; Sener, Ismail; Bulbul, Mehmet; Ezirganl?, Seref; Polat, Hidayet B.

2012-01-01

105

3-D diagnosis-assisted management of anomalous mandibular molar  

PubMed Central

This case report describes the successful non-surgical endodontic management of carious exposed three-rooted mandibular molar with four root canals detected on the pre-operative radiograph taken with 20 degrees mesial angulation and confirmed with a 64-slice helical computed tomography scan-assisted 3-D-reconstructed images. Access cavity shape was modified to locate the extra canal with respect to the distolingual root in the left mandibular first molar. Copious irrigation was accomplished with 5.25% sodium hypochlorite and 17% EDTA. Biomechanical preparation was done using protapers. Calcium hydroxide dressing was done for 1 week. The tooth was obturated using gutta percha and AH 26 root canal sealer, and it was permanently restored with composite. Clinical examination on follow-up visits revealed no sensitivity to percussion and palpation in the left mandibular first molar. Thorough knowledge of root canal variations and use of advanced diagnostic modalities lead to successful non-surgical management of the complex cases.

Mittal, Neelam; Narang, Isha

2012-01-01

106

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.

Baum, William M

2002-01-01

107

Molar macrowear reveals Neanderthal eco-geographic dietary variation.  

PubMed

Neanderthal diets are reported to be based mainly on the consumption of large and medium sized herbivores, while the exploitation of other food types including plants has also been demonstrated. Though some studies conclude that early Homo sapiens were active hunters, the analyses of faunal assemblages, stone tool technologies and stable isotopic studies indicate that they exploited broader dietary resources than Neanderthals. Whereas previous studies assume taxon-specific dietary specializations, we suggest here that the diet of both Neanderthals and early Homo sapiens is determined by ecological conditions. We analyzed molar wear patterns using occlusal fingerprint analysis derived from optical 3D topometry. Molar macrowear accumulates during the lifespan of an individual and thus reflects diet over long periods. Neanderthal and early Homo sapiens maxillary molar macrowear indicates strong eco-geographic dietary variation independent of taxonomic affinities. Based on comparisons with modern hunter-gatherer populations with known diets, Neanderthals as well as early Homo sapiens show high dietary variability in Mediterranean evergreen habitats but a more restricted diet in upper latitude steppe/coniferous forest environments, suggesting a significant consumption of high protein meat resources. PMID:21445243

Fiorenza, Luca; Benazzi, Stefano; Tausch, Jeremy; Kullmer, Ottmar; Bromage, Timothy G; Schrenk, Friedemann

2011-03-18

108

Long-term cost of direct Class II molar restorations.  

PubMed

The aim was to evaluate the theoretical long-term treatment costs of direct class II molar restorations (amalgam, composite, glass ionomer) using the Median Survival Times (MSTs) derived from longevity studies conducted in the Nordic countries as time for replacement. Theoretical long-term cost calculations were based on fee schedules from all Public Dental Services (PDS) in Sweden, for patients, Social Insurance Offices (SI), and total cost. Costs over 10 years were calculated and sensitivity calculations were conducted in order to demonstrate the effect of different MSTs on the long-term cost development. Glass ionomer molar class II restorations had the lowest and composite restorations had the highest initial total cost. The highest total cost over 10 years was seen for composite restorations. Amalgam restorations had the lowest long-term total cost, except when the costs were based on the shortest MSTs for each material. As there were considerable differences in the long-term costs for class II molar restorations with different materials, the importance of cost-analyses over time cannot be enough emphasised when decisions about resource allocation in the dental health insurance system are considered. PMID:12425224

Sjögren, Petteri; Halling, Arne

2002-01-01

109

Variable permanent mandibular first molar: Review of literature  

PubMed Central

Introduction: The success of root canal therapy depends on the locations of all the canals, thourough debridement and proper sealing. At times the clinicians are challenged with variations in morphology of root canal. This review article attempts to list out all the variations of permanent mandibular first molar published so for in the literature. Materials and Methods: An exhaustive search was undertaken using PUBMED database to identify published literature from 1900 to 2010 relating to the root canal morphology of permanent first molar by using key words. The selected artcles were obtained and reviewed. Results: Total ninty seven articles were selected out of which 50 were original article and forty seven were case reports. The incidence of third canal in mesial root was 0.95% to 15%. The incidence of three rooted mandibular first molar was 3% to 33%. Only ninety cases reported with c-shape canal configuration. Incidence of Taurodintism without congenital disorder was very rare. Conclusion: The root canal treatment requires proper knowlegde of variations in root canal morphology in order to recognise, disinfect and seal all portal of exit. This can be accomplished with proper diagnosis using newer modes, modification in access preparation, use of operating microscope, enhanced methods of disinfecting and sealing of all canals.

Ballullaya, Srinidhi V; Vemuri, Sayesh; Kumar, Pabbati Ravi

2013-01-01

110

A Neanderthal lower molar from Stajnia Cave, Poland.  

PubMed

The primary aim of this study was to conduct a taxonomic assessment of the second of three isolated human teeth found in the Stajnia Cave (north of the Carpathians, Poland) in 2008. The specimen was located near a human tooth (S5000), which was identified by Urbanowski et al. (2010) as a Neanderthal permanent upper molar. Both of these teeth were excavated from the D2 layer, which belongs to the D stratigraphic complex comprising the archaeological assemblage associated with the Micoquian tradition. An Ursus spelaeus bone and Mammuthus primigenius tooth that were also excavated from the D2 layer were dated to >49,000 years BP (by AMS (14)C) and 52.9 ka BP (by U-Th), respectively. The sediment overlying stratigraphic complex D was dated to 45.9 ka BP by the OSL method. The S4300 tooth is a lower first or second permanent molar belonging to an individual other than that who once possessed the S5000 tooth. The S4300 tooth exhibits a combination of traits typical of Neanderthal lower molars, including a mid-trigonid crest, large anterior fovea, taurodontism and subvertical grooves on the interproximal face, indicating that this tooth belonged to a Neanderthal individual. The S4300 tooth from Stajnia Cave is one of the oldest human remains found in Poland. PMID:23415376

D?browski, P; Nowaczewska, W; Stringer, C B; Compton, T; Kruszy?ski, R; Nadachowski, A; Stefaniak, K; Urbanowski, M

2013-02-12

111

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.

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

2012-01-01

112

Risk of osteoradionecrosis after extraction of impacted third molars in irradiated head and neck cancer patients  

Microsoft Academic Search

PurposeThis study was performed to compare the risk of osteoradionecrosis (ORN) in head and neck cancer patients in whom 1 or more impacted third molars were extracted before radiotherapy with patients whose impacted third molars were left intact.

Hee-Kyun Oh; Mark S Chambers; Adam S Garden; Pei-Fong Wong; Jack W Martin

2004-01-01

113

Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens  

Microsoft Academic Search

Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo. Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late

Kornelius Kupczik; Jean-Jacques Hublin

2010-01-01

114

Patient with oligodontia treated with a miniscrew for unilateral mesial movement of the maxillary molars and alignment of an impacted third molar.  

PubMed

This report describes the treatment of a 20-year-old woman with a dental midline deviation and 7 congenitally missing premolars. She had retained a maxillary right deciduous canine and 4 deciduous second molars, and she had an impacted maxillary right third molar. The maxillary right deciduous second molar was extracted, and the space was nearly closed by mesial movement of the maxillary right molars using an edgewise appliance and a miniscrew for absolute anchorage. The miniscrew was removed, and the extraction space of the maxillary right deciduous canine was closed, correcting the dental midline deviation. After the mesial movement of the maxillary right molars, the impacted right third molar was aligned. To prevent root resorption, the retained left deciduous second molars were not aligned by the edgewise appliance. The occlusal contact area and the maximum occlusal force increased over the 2 years of retention. The miniscrew was useful for absolute anchorage for unilateral mesial movement of the maxillary molars and for the creation of eruption space and alignment of the impacted third molar in a patient with oligodontia. PMID:23992816

Maeda, Aya; Sakoguchi, Yoko; Miyawaki, Shouichi

2013-09-01

115

Mandibular third molar development after mantle radiation in long-term survivors of childhood Hodgkin's disease  

SciTech Connect

Sequential panoramic radiographs were assessed for mandibular third molar development in 47 long-term survivors of childhood Hodgkin's disease after treatment with 37 Gy mantle field radiation. To make a comparison, panoramic radiographs of 149 healthy, nonirradiated children were reviewed for the presence of mandibular third molars. In children between the ages of 7 and 12 years, bilateral agenesis of mandibular third molars was more frequent in patients who had been treated with mantle radiation than in nonirradiated patients. Unilateral agenesis, crown hypoplasia, and root growth impairment of mandibular third molars were also found. Similar, apparent, radiation-induced developmental anomalies were noted in maxillary third molars of the irradiated patients.

McGinnis, J.P. Jr.; Hopkins, K.P.; Thompson, E.I.; Hustu, H.O.

1987-05-01

116

Unilateral single-rooted primary mandibular first molar.  

PubMed

A 4-year-old boy reported food lodgement and pain in the lower left back tooth region. On examination, a deeply carious tooth with food lodgement was seen. On oral examination, numbers of teeth were found to be carious and required restorations and endodontic treatments according to radiographic evaluation. Radiograph of mandibular left first deciduous molar revealed an unusual morphology of root. It was single-rooted and presented with Vertucci's class I canal. The tooth was treated by pulpectomy followed by a stainless steel crown. All other carious teeth were treated as planned. PMID:23893279

Chaudhari, Purva; Mallikarjuna, Rachappa; Swadas, Milan; Dave, Bhavna

2013-07-26

117

The partial molar volumes of anesthetics in lipid bilayers.  

PubMed

The excess volumes of mixing of benzyl alcohol, halothane, and methoxyflurane in water and in suspensions of several lipid bilayers have been determined at 25 degrees C using a novel excess volume dilatometer. The excess volumes of mixing in water were all found to be negative, whereas in lipid suspensions they were all more positive than those in water alone. From known partition coefficients the partial molar volumes of these three solutes in the lipid bilayers were calculated. These values were all close to the molar volumes of the pure anesthetics, as was a value determined for halothane in olive oil. Halothane was studied in dipalmitoylphosphatidylcholine below its phase transition, and was found to exhibit a much larger excess volume than in any other system we studied. The potency of these three anesthetics was determined in tadpoles. It was calculated that at equi-anesthetic doses these three agents caused an expansion in egg lecithin/cholesterol (2:1) bilayers of 0.21 +/- 0.015%. This result is consistent with the hypothesis that general anesthetics act by expanding membranes. PMID:6895321

Kita, Y; Bennett, L J; Miller, K W

1981-09-21

118

Unilateral failure of development of mandibular premolars and molars in an Eastern Grey kangaroo (Macropus giganteus) and its effects on molar progression.  

PubMed

An adult male Eastern Grey kangaroo from a wildlife reserve near Melbourne was submitted for necropsy examination and was discovered to have abnormal dentition. There was no evidence that any premolars or molars had ever been present on the right mandible, whilst the incisors were normal. The age of the kangaroo was estimated to be 1 year 9 months using the right maxillary molars and 2 years 4 months old using the contralateral side, presumably due to the asymmetry of the dental arcades. 'Lumpy jaw', a common periodontal disease of kangaroos, from which Bacteroides sp was cultured, was present on the base of the vertical ramus of the left mandible. Complete unilateral absence of premolar and molar teeth in the mandible of a kangaroo has not been described. This condition affected molar progression in both sets of maxillary molars. PMID:18271832

Barber, D; Campbell, J; Davey, J; Luke, T; Agren, E; Beveridge, I

119

An in vitro morphological investigation of the endodontic spaces of third molars.  

PubMed

Aim of this paper was to investigate the particular anatomic features of the endodontic space of third molars in the general population of Croatia. A total of 106 fully developed third molars (56 maxillar and 50 mandibular) has been analyzed. The respective number of roots and of root canals, the structure of the roots, and the curvature and absolute length of the root-canals were analyzed. In most cases, upper third molars had three roots (83.9%), while most of the lower molars were single rooted (56.0%). Upper third molars had mostly three root canals (75.1%), lower third molars two (90.0%). In both jaws, most third molars had curved canals (60.7% in the upper and 84.0% in the lower jaw). 12.5% of upper third molars had lateral and accessory canals, whereas only 4.0% of the lower third molars were found to have them. The Student t-test showed statistically significant differences (p < 0.05) in the length of the root-canals, mesiobuccal and distobuccal canals being significantly shorter than palatinal canals. The same test showed that in the lower third molars the mesial root canals were significantly longer that the distal ones, although slightly. The results obtained are in compliance with similar results by other authors; however, they tend to show some specific population-related features. PMID:23940986

Cosi?, Jozo; Gali?, Nada; Vodanovi?, Marin; Njemirovskij, Vera; Segovi?, Sanja; Paveli?, Bozidar; Ani?, Ivica

2013-06-01

120

An Evidenced Based Scoring System to Determine the Periodontal Prognosis on Molars.  

PubMed

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

2013-05-31

121

Molar extinction coefficients of some carbohydrates in aqueous solutions  

NASA Astrophysics Data System (ADS)

Molar extinction coefficients of some carbohydrates viz. L-arabinose (C5H10O5), D-glucose (C6H12O6), D-mannose (C6H12O6), D-galactose (C6H12O6), D(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying within experimental uncertainty. Within concentration ranges studied, Beer--Lambert law is obeyed very well.

Singh, K.; Sandhu, G. K.; Lark, B. S.; Sud, S. P.

2002-03-01

122

Rotation of rectangular wire in rectangular molar tubes. Part I.  

PubMed

The degree of angular rotation of rectangular orthodontic wires in rectangular molar tubes was measured using a rotatable mechanical stage on a Unitron metallograph and compared to theoretical data. It was found that square 0.016 inch wire did not bind in 0.018 by 0.022 inch or larger mandrel- or inconel-formed tubes, whereas rotations of 11 to 23 degrees were noted in cast tubes of this dimension. Although 0.016 by 0.022 inch wire did bind in these tubes, the degree of rotation was far greater than expected on the basis of theoretical calculations or clinical expectations. The results indicated that it was unrealistic to expect fine control of a few degrees of torque to occur as expected for delicate clinical control. PMID:6943934

Raphael, E; Sandrik, J L; Klapper, L

1981-08-01

123

Surface analysis of etched molar enamel by gas adsorption.  

PubMed

Much research has been devoted to the study of etched enamel, since it is critical to bonding. Currently, there are no precise data regarding the etched-enamel specific surface area. The aim of this study was to characterize, by two different methods, the surface of human dental enamel in vitro after being etched. It was hypothesized that differences would be observed between specimens in terms of specific surface area and grade of etching. Sixteen third molar enamel samples were etched for 30 sec with 37% phosphoric acid prior to being viewed by SEM. Etched enamel surfaces were graded according to the Galil and Wright classification. The total surface area of etched samples was determined by the BET gas absorption method. A substantial variability in total surface area was observed between and among samples. A Pearson's Correlation Coefficient showed a lack of relationship between etch pattern and total surface area. PMID:18502960

Orellana, M F; Nelson, A E; Carey, J P R; Heo, G; Boychuk, D G; Major, P W

2008-06-01

124

Molar extinction coefficients of some commonly used solvents  

NASA Astrophysics Data System (ADS)

Molar extinction coefficients of some commonly used solvents (ethanol (C2H5OH), methanol (CH3OH), propanol (C3H7OH), butanol (C4H9OH), water (H2O), toluene (C7H8), benzene (C6H6), carbontetrachloride (CCl4), acetonitrile (C4H3N), chlorobenzene (C6H5Cl), diethylether (C4H10O) and dioxane (C4H8O2)) have been determined by a well-collimated narrow beam transmission geometry at 279, 356, 662, 1173, 1252 and 1332 keV ? rays. The total ? ray interaction cross sections of these solvents have also been determined. A good agreement has been obtained between the experimental results with the theoretical values evaluated through XCOM calculations.

Kumar, Ashok; Singh, Sukhpal; Singh Mudahar, Gurmel; Singh Thind, Kulwant

2006-07-01

125

Partial molar volumes of uni-univalent electrolytes in methanol + water; 1: Lithium chloride, sodium chloride, and potassium chloride  

SciTech Connect

Densities of methanol + water + lithium chloride, + sodium chloride, and + potassium chloride were measured at 15, 25, 35, and 45 C. The apparent molar volumes of the electrolytes in these mixtures were calculated, and the apparent molar volumes at infinite dilution, the partial molar volumes, and partial molar thermal expansivities were evaluated.

Takenaka, Nobuo; Takemura, Takeshi; Sakurai, Masao (Hokkaido Univ., Sapporo (Japan). Research Inst. for Electronic Science)

1994-04-01

126

Excess molar volumes and apparent molar volumes of some amide + water systems at 303.15 and 308.15 K  

SciTech Connect

Excess molar volumes V{sub m}{sup E} for the binary mixtures of N-methylformamide, N,N-dimethylformamide, 2-pyrrolidinone, N-methyl-2-pyrrolidinone, and N,N-dimethylacetamide with water have been measured using a continuous-dilution dilatometer at 303.15 and 308.15 K as a function of composition. In all mixtures, the excess molar volumes are negative over the entire composition range. The results were used to estimate the apparent molar volumes of the components. The values of these two properties have been discussed in terms of intermolecular interactions between the mixing components of the binary mixture.

Pal, A.; Singh, Y.P. [Univ. of Kurukshetra (India). Dept. of Chemistry

1995-07-01

127

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

PubMed Central

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.

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

2010-01-01

128

Human molars from later Pleistocene deposits of Witkrans Cave, Gaap Escarpment, Kalahari Margin  

Microsoft Academic Search

Human molars from travertine deposits of Witkrans Cave (Gaap Escarpment, northern Cape Province, South Africa) are described.\\u000a The Witkrans molars were discovered in direct association with later Pleistocene faunal remains and a sample of Middle Stone\\u000a Age artifacts (Peabody, 1954; Clark, 1971; Sampson, 1974; Klein, 1984; Volman, 1984). The morphology and dimensions of the\\u000a Witkrans molars resemble remains from other

Monte L. McCrossin

1992-01-01

129

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

130

[Maxillary second molar with curved single root and single canal: a case report].  

PubMed

Incidence rate of single root canal in maxillary second molar is very low. The emergence of curved single root canal in maxillary second molar with single root is especially rare. A case of curved single root canal in maxillary second molar with single root was successfully treated and reported in this article. This report also highlighted the role of cone beam computed tomography as an objective method to confirm the three-dimensional anatomy of teeth. PMID:21427914

Wang, Yao; Hui, Xi; Huang, Ding-ming

2011-02-01

131

Partial molar volumes of sulfur dioxide in organic solvents: Formation of charge-transfer complexes  

Microsoft Academic Search

New apparatus for measuring the apparent molar volumes of gases in liquids is described. The apparatus has been used to obtain the limiting partial molar volume of sulfur dioxide in 17 organic solvents. The limiting partial molar volume of sulfur dioxide is found to be significantly smaller in electron-donating solvents that in non-electron-donating solvents, with this difference being interpreted in

John F. Smith; Gerald A. Bottomley; Leslie Barta; Loren G. Hepler

1990-01-01

132

Quantification of chlorinated naphthalenes with GC-MS using the molar response of electron impact ionization  

Microsoft Academic Search

The concept of the molar response (MR) in HRGC\\/EI-MS has been checked for naphthalene and three chlorinated naphthalenes: 1-chloronaphthalene, 1,2,3,4-tetrachloronaphthalene and octachloronaphthalene. The molar response factors increase with increasing degree of chlorination. When the ion yield is normalized for the ionization cross section Q of the molecule, a constant value of injected molar mass to signal intensity is obtained for

Thomas Wiedmann; Karlheinz Ballschmiter

1993-01-01

133

Management of mandibular first molar with four canals in mesial root.  

PubMed

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

2013-09-01

134

Three-rooted mandibular first primary molar: Report of three cases.  

PubMed

Accessory root formation in primary teeth is an uncommon finding. An awareness and understanding of the presence of additional roots and unusual root canal morphology is essential as it determines the successful outcome of the endodontic treatment.This paper presents three case reports on the presence of three-rooted mandibular first primary molar (primary three-rooted mandibular left first molar and bilateral mandibular first molar). PMID:22629056

Gupta, Shilpi; Nagaveni, N B; Chandranee, N J

2012-04-01

135

Three-rooted mandibular first primary molar: Report of three cases  

PubMed Central

Accessory root formation in primary teeth is an uncommon finding. An awareness and understanding of the presence of additional roots and unusual root canal morphology is essential as it determines the successful outcome of the endodontic treatment. This paper presents three case reports on the presence of three-rooted mandibular first primary molar (primary three-rooted mandibular left first molar and bilateral mandibular first molar).

Gupta, Shilpi; Nagaveni, N. B.; Chandranee, N. J.

2012-01-01

136

Independent and Confluent Middle Mesial Root Canals in Mandibular First Molars: A Report of Four Cases  

PubMed Central

Mandibular molars demonstrate considerable variations with respect to number of roots and root canals. The possibility of additional root canals should be considered even in teeth with a low frequency of abnormal root canal anatomy. This paper discusses the endodontic management of the rare anatomical complexity middle mesial canals in mandibular first molar and also serves to remind the clinicians that such anatomical variations should be taken into account during the endodontic treatment of the mandibular molars.

Deepalakshmi, Mohanavelu; Karumaran, Chellasamy Savarimala; Miglani, Revathi; Indira, Rajamani

2012-01-01

137

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. Am J Phys Anthropol 152:186-196, 2013. © 2013 Wiley Periodicals, Inc. PMID:24009105

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

2013-09-05

138

Evaluation of the molar volume of silicon crystals for a determination of the Avogadro constant  

Microsoft Academic Search

For a determination of the Avogadro constant by the X-ray crystal density method, the molar volume of three different silicon crystals has been evaluated by absolute measurements of their densities and molar masses. The results have shown that the molar volume is 12.058 8279 (22) cm3 mol-1. When this value is combined with the lattice constant recommended by the CODATA

Kenichi Fujii; Atsushi Waseda; Naoki Kuramoto; Shigeki Mizushima; Mitsuru Tanaka; Staf Valkiers; Philip Taylor; Rüdiger Kessel; Paul De Bievre

2003-01-01

139

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.

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

2013-01-01

140

Pharmacodynamic responses of exogenous epinephrine during mandibular third molar surgery  

PubMed Central

Background: The systemic effects attributable to the injection of dental local anesthetic solutions have been the subject of discussion for many years. Aim and Objective: The aim of the present study was to investigate the biochemical and hemodynamic effects of adrenaline in lignocaine local anesthetic solutions when used in clinical doses in patients undergoing third molar surgery under general anesthesia. Materials and Methods: Of the total 30 patients, 15 were given local anesthetic solution containing adrenaline and the other 15 were given the same without adrenaline. Hemodynamic and biochemical parameters were recorded at considerable intervals. The changes from the pre-local anesthetic (baseline) values with each treatment were compared by analysis of variance and Student's t-test. The changes within each treatment were compared by the paired t-test. Results and Conclusion: This study shows that exogenous adrenaline administration in clinical doses produces systemic effects even in conditions where the endogenous release of the catecholamines would be expected to be considerable.

Sivanmalai, Sivaraj; Annamalai, Sivakumar; Kumar, Santhosh; Prince, Christo Naveen; Chandrakala; Thangaswamy, Vinod

2012-01-01

141

Management of middle mesial canal in mandibular second molar  

PubMed Central

The primary objective of endodontic therapy is to achieve a three-dimensional obturation of the root canal space after adequate preparation of the canal space to remove the tissue debris, microorganisms, and their byproducts. Anatomical variations have frequently been encountered in endodontic practice and have to be adequately managed by the clinician. Missed roots and canals are a major reason for failure of therapy. Technological advances have given the clinician ample opportunity to identify and treat these aberrations successfully. The present report describes a left mandibular second permanent molar requiring root canal treatment, found to have three separate canals in the mesial root. This case demonstrates a rare anatomical configuration and emphasizes the need for the clinician to be aware of and look out for such variations and use adequate diagnostic methodologies prior to and during therapy to detect such variations. The possibility of additional canals, whenever in doubt, should be explored with the assistance of technologies such as those of magnification and illumination and various diagnostic aids. Operator experience has also shown to be a key factor in negotiation and management of these aberrant canal configurations.

Karunakaran, J. V.; Shobana, R.; Kumar, Mohan; Kumar, Senthil; Mankar, Sunil

2012-01-01

142

Mass or molar? Recommendations for reporting concentrations of therapeutic drugs.  

PubMed

A working party (WP) from the Australasian Association of Clinical Biochemists, Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists, Royal College of Pathologists of Australasia and Royal Australasian College of Physicians recommends the following: *mass units should be used for reporting therapeutic drug concentrations in Australia and New Zealand; and the litre (L) should be used as the denominator when expressing concentration. Examples of these units are mg/L and ?g/L Exceptions to these principles include: *drugs for which there is current uniformity of reporting and supporting information using molar units, notably lithium (mmol/L) and methotrexate (?mol/L); *drugs that are also present as endogenous substances, where the units used routinely should continue to be used. This applies to many substances, including minerals (eg, iron; ?mol/L), vitamins (eg, vitamin D; nmol/L) and hormones (eg, thyroxine; pmol/L). *drugs for which the denominator is not a 198 of fluid and there is international uniformity of reporting (eg, thiopurine metabolites; per 109 red blood cells). These recommendations relate to drugs that are used therapeutically, whether measured for therapeutic drug monitoring purposes or for assessment of overdose. Other substances, such as drugs of misuse, heavy metals or environmental toxins, were not considered by the WP and are thus not covered by this document. These recommendations should also be applied to other supporting documentation such as published guidelines, journal articles and websites. The implementation of these recommendations in New Zealand is subject to local confirmation. PMID:23581955

Jones, Graham R D; Bryant, Stewart; Fullinfaw, Robert; Ilett, Ken; Miners, John O; Morris, Raymond G; Doogue, Matthew P

2013-04-15

143

Root canals in two-rooted maxillary second molars.  

PubMed

The aim of this study was to register the root canal number, root canal position, and root canal cross-section in human two-rooted, permanent maxillary second molars. One hundred and fifty-nine such teeth extracted in Denmark were cross-sectioned at the mid-root level and apically in accordance with precise guidelines. The observations were made in a stereomicroscope, corresponding to the above-mentioned section levels. At mid-root there were two canals present in 11% of the teeth examined; the canals were located mesially and distofacially, mesiofacially and distally, or facially and lingually. Three canals positioned mesiofacially, distofacially, and lingually were observed in 89% of the teeth. At the same level 62% of the canal cross-sections were noncircular, some being, for instance, C-shaped, whereas 38% of the cross-sections were circular. Apically, two canals were found, representing 19% of the teeth, with the canal position as at mid-root; 81% of the teeth were three-canaled with the same canal position as at mid-root. At the apical level 60% of the canal cross-sections were noncircular, whereas 40% of the cross-sections were circular. PMID:9477024

Carlsen, O; Alexandersen, V

1997-12-01

144

Incidence of oral sinus communications in 389 upper third molar extraction  

Microsoft Academic Search

Introduction. The incidence of oral sinus communications (OSC) following the extraction of an upper third molar re- mains uncertain. Objectives. The purpose of this study was to determine the incidence of OSC following the extraction of 389 consecu- tive upper third molars during 2003 in the Master of Oral Surgery and Orofacial Implantology (Barcelona University, Spain). Patients and method. Different

Marta del Rey Santamaría; Eduard Valmaseda Castellón; Leonardo Berini Aytés; Cosme Gay Escoda

145

Influence of overlay restorative materials and load cusps on the fatigue resistance of endodontically treated molars  

Microsoft Academic Search

Objectives: To assess the influence of restorative materials and load cusps on the fatigue resistance of endodontically treated molars. Method and Materials: Thirty extracted molars received root canal treatment followed by a standardized tooth preparation (3-mm cuspal reduction and immediate dentin sealing). Twenty Cerec 3 overlays (Sirona Dental Systems) were milled in the ceramic Vita MKII block (Vident; groups MKIIGL

Pascal Magne; Alena Knezevic

146

A new method to correct lingual rolling of lower molars (Amini twister).  

PubMed

In this report, we present an uncomplicated approach to overcome lingual rolling of mandibular molars during orthodontic treatment, by using rectangular NiTi arch wire in twist fashion through the molar tube. The sequential steps of the twist manoeuvre on a typodont and a case report are exhibited in this article. PMID:23729138

Amini, Fariborz; Poosti, Maryam

2013-01-01

147

Enamel thickness and the helicoidal wear plane in modern human mandibular molars  

Microsoft Academic Search

Helicoid occlusion has long been recognized as a feature characterizing the human dentition and has been viewed as an important morphological marker in the transition from Australopithecus to Homo. The hallmark of helicoidal wear is a buccal wear slope in anterior mandibular molars (and a corresponding lingual slope of wear in anterior maxillary molars) reversing to a flat or lingual-oriented

Gary T. Schwartz

2000-01-01

148

Morphological and anthropological aspects of human triangular deciduous lower first molar teeth  

Microsoft Academic Search

The crown and root morphology, and bilateral occurrence of human deciduous lower first molars that exhibited a triangular occlusal outline, taken from excavated samples of Japanese, Jomonese and Iraqi origin, were investigated. The crowns of triangular teeth had smaller mesiodistal and larger buccolingual diameters than normally shaped deciduous lower first molars. An elongated buccolingual diameter was derived from the buccal

Yoshikazu Kitagawa; Yoshitaka Manabe; Joichi Oyamada; Atsushi Rokutanda

1996-01-01

149

Influence of a Barley Product on the Eruption and Caries of Rat Molars  

Microsoft Academic Search

SYNOPSIS IN INTERLINGUALE INFLUENTIA DE UN PRODUCTO DE HORDEO SUPER LE ERUPTION E LE CARIOGENESE DE MOLARES DE RATTOS.—Le substitution de hordeo pro 20 pro cento de un dieta componite secundo datos de human consumo medie causava un plus precoce eruption del tertie molares in rattos de secunde generation del linea Wistar durante que inhibition de carie dental esseva constatate

L. M. Dalderup; M. M. Stroo

1966-01-01

150

Effect of Primary Molar Extraction on Gingival Emergence of Succedaneous Tooth  

Microsoft Academic Search

SYNOPSIS IN INTERLINGUALE EFFECTO DEL EXTRACTION DE MOLARES PRIMARI SUPER LE EMERGENTIA GINGIVAL DEL DENTES SUCCEDANEE.—Le tempore del emergentia gingival de dentes bicuspidal subjacente a bilateralmente comparabile pares de primari dentes molar, un del quales esseva extrahite durante que le altere se exfoliava naturalmente, esseva comparate a base de serial modulos dental e de roentgenogrammas in 20 juveniles norteamerican de

W. F. OMeara

1966-01-01

151

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

152

Developing a measure of patient perceptions of short-term outcomes of third molar surgery  

Microsoft Academic Search

Purpose: The purpose of the study was to develop an instrument to measure patients' perceptions of their experiences after the removal of third molar teeth.Methods: Nineteen patients (ages 18 to 25 years) who underwent surgical removal of four third molars after local treatment for mild symptoms of pericoronitis completed a newly developed 14-item instrument each evening for the 14-day period

Daniel A Shugars; Ken Benson; Raymond P White; Kit N Simpson; James D Bader

1996-01-01

153

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

154

Evaluation of factors predictive of lingual nerve injury in third molar surgery  

Microsoft Academic Search

The aim of this study was to investigate risk factors for temporary and permanent lingual nerve injury after extraction of mandibular third molars. It was based on a 4-year prospective study of 2134 consecutive mandibular third molar operations in 1384 consecutive day case patients. During the study period (1994–1998) data were collected prospectively on patient, dental and surgical factors and

T. Renton; M. McGurk

2001-01-01

155

Success rate of formocresol pulpotomy in primary molars restored with stainless steel crown vs amalgam  

Microsoft Academic Search

Purpose: The purpose of this retrospective study was to compare the success rates of formocresol pulpotomy in primary molars restored with stainless steel crowns (SSC) to those restored with amalgam (AM). Methods: Radiographs of pulpotomized primary molars restored with SSC or AM in the principal author's pediatric dentist practice were evaluated and defined as a \\

Gideon Holan; Anna B. Fuks

2002-01-01

156

Mineral trioxide aggregate vs. formocresol in pulpotomized primary molars: a preliminary report  

Microsoft Academic Search

Purpose: The aim of this study was to compare the effect of mineral trioxide aggregate (MTA) to that of formocresol (FC) as pulp dressing agents in pulpotomized primary molars with cari- ous pulp exposure. Methods: Forty-five primary molars of 26 children were treated by a conventional pulpotomy technique. The teeth were randomly assigned to the MTA (experimental) or FC (control)

Eliezer Eidelman; Anna B. Fuks

2001-01-01

157

Comparison of mineral trioxide aggregate and formocresol as pulp medicaments for pulpotomies in primary molars  

Microsoft Academic Search

Purpose The aim of this study was to compare the effect of white mineral trioxide aggregate (MTA) to that of formocresol (FC) as pulp dressing agents in pulpotomised primary molars.Methods In this clinical trial study, 60 lower second primary molars of 46 children were treated by a conventional pulpotomy technique. The teeth were randomly assigned to the MTA (experimental) and

H. Noorollahian

2008-01-01

158

Partial molar volumes in aqueous mixtures of nonelectrolytes. II. Isopropyl alcohol  

Microsoft Academic Search

Densities of isopropyl alconol-water mixtures were measured over the entire mole fraction range at 5, 15, 25, 35 and 45°C. Apparent and partial molar volumes and partial molar expansibilities were derived for both components. The results were compared with those of a previous investigation of t-butyl alcohol-water mixtures.

Masao Sakurai

1988-01-01

159

40 CFR 1066.610 - Mass-based and molar-based exhaust emission calculations.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Mass-based and molar-based exhaust emission...PROCEDURES Calculations § 1066.610 Mass-based and molar-based exhaust emission calculations. (a) Calculate your total mass of emissions over a test cycle as...

2013-07-01

160

High school students' ability to solve molarity problems and their analog counterparts  

Microsoft Academic Search

The study investigates the use of analog tasks for determining difficulties that high school chemistry students might encounter in solving molarity problems. Students (n = 619) from five schools completed three tests given throughout the school year. These were: an analog test, a molarity test, and a retention test. The analog task consisted of dissolving lemonade powder for solid sodium

Dorothy L. Gabel; K. V. Samuel

1986-01-01

161

Postoperative Infection after Surgical Removal of Impacted Mandibular Third Molars: An Analysis of 110 Consecutive Procedures  

Microsoft Academic Search

Objective: The aim of this study was to evaluate the rate of postoperative infection and other complications after the surgical removal of impacted mandibular third molars. Subjects and Materials: Medical records of 110 consecutive patients with 130 consecutive surgical extractions of impacted lower third molar teeth performed under local anesthetic using strict aseptic techniques were reviewed and analyzed. No systemic

Adel Al-Asfour

2009-01-01

162

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

163

A New Anatomically Based Nomenclature for the Roots and Root Canals--Part 1: Maxillary Molars  

PubMed Central

Numerous terminologies have been employed in the dental literature to describe the roots and root canal systems of maxillary molars. This multiplicity in naming of roots and canals makes the reader susceptible to misinterpretation and confusion. No consensus thus far has been arrived at for defining the names of roots and root canals in maxillary molars, including their various morphological aberrations. The anatomical relation of roots and their root canals were identified and were subsequently named based on definite sets of criteria. A new method for identification and naming of roots and root canal anatomy in maxillary molars, based on their root and canal relationship, was formulated and is presented in this paper. The nomenclature makes certain essential modifications to the traditional approach to accommodate naming of the various aberrations presented in the maxillary molars. A simple, yet extensive, nomenclature system has been proposed that appropriately names the internal and external morphology of maxillary molars.

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

2012-01-01

164

Growth hormone, prolactin and chorionic somatomammotropin in normal and molar pregnancy.  

PubMed

Twenty patients with molar pregnancy, ten normal pregnant women and ten healthy non-pregnant women were given 30 g of arginine intravenously. The serum concentration of growth hormone, prolactin and chorionic somatomammotropin (CS) was determined by radioimmunoassay. In addition, serum 17beta-estradiol, estriol and progesterone were also measured. Arginine infusion induced a sharp rise of GH in patients with molar pregnancy and in nonpregnant subjects, but the response in normal pregnancy was blunted. The response of PRL was high in patients with molar pregnancy, blunted in normal pregnancy and very small in nonpregnant subjects. CS did not respond at all to arginine infusion both in normal pregnancy and molar pregnancy. The high response to argine of PRL, normal response of GH and low baseline secretion and no response of CS may be characteristic of molar pregnancy. PMID:956347

Mochizuki, M; Morikawa, H; Kawaguchi, K; Tojo, S

1976-09-01

165

Optimization of the mineral content in polymeric gels: The effect of calcium to phosphate molar ratio  

NASA Astrophysics Data System (ADS)

The influence of calcium to phosphate (Ca/P) molar ratio on the extent of mineralization in a model (poly)acrylamide gel was investigated under simulated physiological conditions. We hypothesized that the optimal growth of hydroxyapatite crystals will take place at the stoichiometric Ca/P molar ratio of 1.67. Phosphate ions were incorporated during the polymerization of the gel and mineralization was initiated by submersion of the gel in calcium acetate solution. Ca/P molar ratios were varied in the range of 0.5 5.0. The mineralized gel was characterized by Raman spectroscopy, scanning electron microscopy (SEM) and mineral weight fraction analysis via ashing. Raman spectra captured across the bulk of the gels indicated the presence of mineral at the core section. The phosphate symmetric stretching peak was observed in the range of 955 960 cm-1 which is characteristic of hydroxyapatite. SEM images showed that crystals formed at Ca/P=2.0 were denser and larger in size than at other molar ratios. In agreement with SEM images, the dry weight fraction of mineral reached the maximum at the molar ratio of 2.0 and the extent of mineralization rapidly declined as the molar ratio diverged from 2.0. Also, the crystallinity of the mineral was optimum at the molar ratio of 2.0. Thus it appears that for effective mineralization, the molar ratio of the two ions needs to be in excess of the stoichiometric requirement, suggesting that ions are expended in processes other than the formation and growth of hydroxyapatite crystals. Therefore, the optimal level of mineralization in biomimetic-based growth of calcium phosphate crystals in sol gel environment requires consideration of a range of molar ratios as opposed to using the molar ratios corresponding to that of the crystal species intended to grow.

Das, Prasenjit; Akkus, Ozan; Azad, Abdul-Majeed

2005-07-01

166

Root and canal morphology of permanent mandibular molars in a Sri Lankan population.  

PubMed

The main purpose of this study was to investigate the root and canal morphology of Sri Lankan mandibular molars and to determine the affinities of these morphological variations to those of people of European and Asian origin. Two hundred mandibular first and second molars were examined. The number of roots and the prevalence of C-shaped (gutter-shaped) roots in mandibular second molars were recorded. Root canal morphology was studied using a clearing technique. The examination of root canal systems of the teeth was based on Vertucci's classification. Among mandibular first molars, only 3% had three roots. Mesial roots of the first molar typically presented with two canals and two apical foramina with type IV, V, or VI canal configuration. Most distal roots of the first molar presented with a type I canal configuration. The remainder were distributed mainly between types III and V. Among mandibular second molars, 6% had single C-shaped roots, while C-shaped canals were found in only 2%. The majority of mesial roots of the second molar showed one or two canals, with one apical foramen with type I, II, or III canal morphology. In addition, the distal root commonly showed type I canal configuration. Intercanal communications and lateral canals were more frequently seen in the first molar than in the second. The root canal morphology in mandibular molars varies among population groups. Mandibular root and canal morphology of Sri Lankan people has closer affinities with that of people of European than of East Asian origin. PMID:17660977

Peiris, Roshan; Takahashi, Masami; Sasaki, Kayoko; Kanazawa, Eisaku

2007-07-25

167

Characterization of stem and progenitor cells in the dental pulp of erupted and unerupted murine molars  

PubMed Central

In the past few years there have been significant advances in the identification of putative stem cells also referred to as “mesenchymal stem cells” (MSC) in dental tissues including the dental pulp. It is thought that MSC in dental pulp share certain similarities with MSC isolated from other tissues. However, cells in dental pulp are still poorly characterized. This study focused on the characterization of progenitor and stem cells in dental pulps of erupted and unerupted mice molars. Our study showed that dental pulps from unerupted molars contain a significant number of cells expressing CD90+/CD45-, CD117+/CD45-, Sca-1+/CD45- and little if any CD45+ cells. Our in vitro functional studies showed that dental pulp cells from unerupted molars displayed extensive osteo-dentinogenic potential but were unable to differentiate into chondrocytes and adipocytes. Dental pulp from erupted molars displayed a reduced number of cells, contained higher percentage of CD45+ and lower percentage of cells expressing CD90+/CD45-, CD117+/CD45- as compared to unerupted molars. In vitro functional assays demonstrated the ability of a small fraction of cells to differentiate into odontoblasts, osteoblasts, adipocytes and chondrocytes. There was a significant reduction in the osteo-dentinogenic potential of the pulp cells derived from erupted molars compared to unerupted molars. Furthermore, the adipogenic and chondrogenic differentiation of pulp cells from erupted molars was dependent on a long induction period and infrequent. Based on these findings we propose that the dental pulp of the erupted molars contain a small population of multipotent cells, whereas the dental pulp of the unerupted molars does not contain multipotent cells but is enriched in osteo-dentinogenic progenitors engaged in the formation of coronal and radicular odontoblasts.

Balic, Anamaria; Aguila, H. Leonardo; Caimano, Melissa J.; Francone, Victor P.; Mina, Mina

2010-01-01

168

Pulpal responses to cavity preparation in aged rat molars.  

PubMed

The dentin-pulp complex is capable of repair after tooth injuries including dental procedures. However, few data are available concerning aged changes in pulpal reactions to such injuries. The present study aimed to clarify the capability of defense in aged pulp by investigating the responses of odontoblasts and cells positive for class II major histocompatibility complex (MHC) to cavity preparation in aged rat molars (300-360 days) and by comparing the results with those in young adult rats (100 days). In untreated control teeth, immunoreactivity for intense heat-shock protein (HSP)-25 and nestin was found in odontoblasts, whereas class-II-MHC-positive cells were densely distributed in the periphery of the pulp. Cavity preparation caused two types of pulpal reactions based on the different extent of damage in the aged rats. In the case of severe damage, destruction of the odontoblast layer was conspicuous at the affected site. By 12 h after cavity preparation, numerous class-II-MHC-positive cells appeared along the pulp-dentin border but subsequently disappeared together with HSP-25-immunopositive cells, and finally newly differentiated odontoblast-like cells took the place of the degenerated odontoblasts and acquired immunoreactivity for HSP-25 and nestin by postoperative day 3. In the case of mild damage, no remarkable changes occurred in odontoblasts after operation, and some survived through the experimental stages. These findings indicate that aged pulp tissue still possesses a defense capacity, and that a variety of reactions can occur depending on the difference in the status of dentinal tubules and/or odontoblast processes in individuals. PMID:16767403

Kawagishi, Eriko; Nakakura-Ohshima, Kuniko; Nomura, Shuichi; Ohshima, Hayato

2006-06-10

169

Root canal anatomy of mandibular second molars. Part I.  

PubMed

The root canal anatomy of 149 mandibular second molars was studied using a technique in which the pulp was removed, the canal space filled with black ink and the roots demineralized and made transparent. Of the 149 teeth, 22 per cent had single roots, 76 per cent had two roots and 2 per cent had three roots. In the single-rooted teeth, three canals were most common, while in the mesial root of the two-rooted teeth, two canals that joined near the apex and one canal in the distal root were most frequent. Round canals were most common in two-rooted teeth and C-shaped canals in single-rooted teeth. Transverse anastomoses were found in 33 per cent of roots, most commonly in the middle third of the root. Lateral canals were found in 72 per cent of roots, most commonly in the apical third of the root. The apical foramen was positioned at the apex in only 33 per cent of roots, and apical deltas were found in 35 per cent. The patient's age and race affected canal shape, with more round canals present in patients over 35 years of age, and more C-shaped canals in Asians. The sex of the patient and the side of the mouth affected the presence of apical deltas, with more being found in males and on the left side. Single-rooted teeth had more complex root canal systems than two-rooted teeth, with more lateral canals, transverse anastomoses, apical deltas and C-shaped canals. PMID:2391179

Manning, S A

1990-01-01

170

Root canals in one-rooted maxillary second molars.  

PubMed

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth extracted in Denmark. The collection currently contains 104 one-rooted, permanent maxillary second molars. The root complex on these teeth was sectioned at the junction between the coronal and the apical halves, i.e. mid-root, and at the junction between the middle and the apical thirds, i.e. apically. Using a stereomicroscope we then registered, mid-root and apically, the following variables: canal number, canal position, and canal cross-section. Mid-root there was 1 centrally located root canal in 25.96% of the teeth examined; 2 canals were observed either mesially and distofacially, mesiofacially and distally, or facially and lingually in 34.62%; 3 canals positioned mesiofacially, distofacially, and lingually were found in 39.42%. At the same level 63.51% of the canal cross-sections were non-circular, whereas 36.49% of the canals had a circular cross-section image. The non-circular canal cross-sections could more specifically be characterized as C-shaped, Y-shaped, hourglass-shaped or the root canal had a greater faciolingual than mesiodistal extension or, respectively, a greater mesiodistal than faciolingual extension. Apically there was 1 centrally located root canal in 35.58%; 2 canals were observed with a position either mesially and distofacially, mesiofacially and distally, or facially and lingually in 37.49%; 3 canals located mesiofacially, distofacially, and lingually were found in 26.92%. At the apical level, 64.32% of the root canal cross-sections were non-circular, whereas 35.68% of the canals showed a circular cross-section. The results presented here are aimed at: clinical dentists, endodontists, and dental morphologists. PMID:1411268

Carlsen, O; Alexandersen, V; Heitmann, T; Jakobsen, P

1992-10-01

171

Alveolar bone loss and restorative dentistry in the primary molars.  

PubMed

This study examined the relationship between the status of the interproximal alveolar bone and the nature of the adjacent proximal surfaces in the primary molar area. In bite wing radiographs of 354 children, aged 6 to 9 years, 5091 sites were examined; 72.7% of the sites were adjacent to intact proximal surfaces, 14.2% to untreated proximal carious surfaces, and 13.0% to restored proximal surfaces. Marginal alveolar bone loss (ABL) was evident in 26.8% of the children, at 4.0% of the sites. Two thirds of the children with ABL had bone defects in more than 1 site. Males had a significantly higher mean number of sites affected with marginal ABL, per child, than females (mean = 2.4, SE = 0.2 and mean = 1.8, SE = 0.2 respectively). ABL was found adjacent to: 0.8% of the intact surfaces; 16.9% of the carious surfaces; 7.8% of the restored surfaces; 1.8% and 53.8% of the sites without or with proximal contact loss respectively; 3.8% and 30.8% of the sites with or without an adequate amalgam restoration respectively; 4.9% and 25.8% of the sites with an adequate or inadequate crown restoration respectively. The differences in distribution of marginal alveolar bone loss were highly significant (Chi square analysis, p = < 0.0001) for sites with intact, carious or restored sites, and for the presence or absence of contact loss, adequate amalgam or adequate crown. PMID:9161207

Bimstein, E; Zaidenberg, R; Soskolne, A W

1996-01-01

172

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.

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

2002-01-01

173

Distal movement of mandibular molars in adult patients with the skeletal anchorage system.  

PubMed

The skeletal anchorage system (SAS) consists of titanium anchor plates and monocortical screws that are temporarily placed in either the maxilla or the mandible, or in both, as absolute orthodontic anchorage units. Distalization of the molars has been one of the most difficult biomechanical problems in traditional orthodontics, particularly in adults and in the mandible. However, it has now become possible to move molars distally with the SAS to correct anterior crossbites, maxillary dental protrusion, crowding, and dental asymmetries without having to extract premolars. This study evaluated the treatment and posttreatment changes during and after distalization of the mandibular molars. In 15 adult patients (12 women and 3 men), a total of 29 mandibular molars were successfully distalized with SAS. The amount of distalization and relapse and the type of tooth movement were analyzed with cephalometric radiographs and dental casts. The average amount of distalization of the mandibular first molars was 3.5 mm at the crown level and 1.8 mm at the root level. The average amount of relapse was 0.3 mm at both the crown and root apex levels. Of 29 mandibular molars, 9 were tipped back, and the others were translated distally in accordance with the established treatment goals. SAS is a viable modality to move mandibular molars for distally correcting anterior crossbites, malocclusions characterized by mandibular anterior crowding, and dental asymmetries. PMID:14765050

Sugawara, Junji; Daimaruya, Takayoshi; Umemori, Mikako; Nagasaka, Hiroshi; Takahashi, Ichiro; Kawamura, Hiroshi; Mitani, Hideo

2004-02-01

174

Factors Affecting the Treatment Decisions and Outcome of Root-Resected Molars: A Nationwide Study.  

PubMed

Background: Treatment of furcation-involved molars represents a clinical challenge. This study retrospectively investigated the demographic parameters affecting the treatment decisions and outcome of root-resected molars by using a nationwide population-based dataset. Methods: A total of 471 eligible patients' de-identified data were obtained from a representative cohort composed of one million of Taiwan's population. Demographic factors which influence the treatment decisions and outcome of root-resected teeth were examined. Cox regression was performed to statistically analyze the factors. Results: The overall survival rates for root-resected molars were 91.1%. The survival times of the extracted and surviving teeth were 303.0 ± 274.6 and 551.8 ± 327.2 days, respectively (p<0.001). Of the analyzed subjects-related factors, such as living district, urbanization level, medical institutions, and monthly income have remarkable influence on treatment decisions; however, there is no statistically difference in survival rate between the root-resected molars receiving flap surgery or not (p=0.504). After adjusting for other factors, patients aged over 74 years have 3.33 times (hazard ratio=3.33; 95% CI=1.04-10.66; p=0.043) higher rate of molar extraction than younger counterparts. Conclusions: The overall survival rate of root-resected molars was satisfied, whereas subjects with advanced age > 74 years had a higher risk of extraction occurrence on resected molars. Subjects-related factors may influence the treatment decision on molars received flap surgery or not. These findings suggest that demographic factors should be carefully evaluated prior and after performing root resection procedure as these factors may eventually have impact on the outcome of root-resected molars. PMID:23327113

Yuh, Da-Yo; Cheng, Guo-Liang; Chien, Wu-Chien; Chung, Chi-Hsiang; Lin, Fu-Gong; Shieh, Yi-Shing; Fang, Wen-Hui; Mau, Lian-Ping; Fu, Earl; Huang, Ren-Yeong

2013-01-17

175

High school students' ability to solve molarity problems and their analog counterparts  

NASA Astrophysics Data System (ADS)

The study investigates the use of analog tasks for determining difficulties that high school chemistry students might encounter in solving molarity problems. Students (n = 619) from five schools completed three tests given throughout the school year. These were: an analog test, a molarity test, and a retention test. The analog task consisted of dissolving lemonade powder for solid sodium hydroxide. Results indicate that the analog task is a predictor of success on the molarity test; that difficulties encountered on the analog test are similar to those on the chemistry test, and that achievement on some types of chemistry problems might be improved by us in analog tasks in instruction.

Gabel, Dorothy L.; Samuel, K. V.

176

Removal of a Maxillary Third Molar Displaced into Pterygopalatine Fossa via Intraoral Approach  

PubMed Central

The removal of impacted maxillary third molars is one of the most common procedures performed in oral and maxillofacial surgery units with low rates of complications and morbidity. A few cases of accidental displacement of third molars into adjacent anatomical spaces, such as the infratemporal fossa, the pterygomandibular space, the maxillary sinus, buccal space, or the lateral pharyngeal space, during surgical interventions have been reported. In this paper, a case of a maxillary third molar accidentally displaced into the pterygopalatine fossa is presented, and the removal of the tooth via intraoral approach is described.

Ozer, Nedim; Ucem, Fulya; Saruhanoglu, Alp; Yilmaz, Serdar; Tanyeri, Hakk?

2013-01-01

177

[The appearance test of a molar tooth with phase shift shadow moiré].  

PubMed

Modern photo-mechanics testing techniques are widely used in industrial circles and academic circles. In order to solve the problem of biomedical engineering, shadow moiré method is used in oral and dental area in our study. A molar tooth was tested by phase shift shadow moiré method. Through testing molar tooth, the results show that shadow moiré method could be used for measuring the appearance of the oral area and concave and convex parts of molar tooth could also be distinguished and shown by interference patterns. The characteristics of shadow moirh are that it does't need exerting load on the specimen and could realize non-contact measurement. PMID:24059045

Mi, Honglin

2013-08-01

178

Two-Rooted Maxillary First Molars with Two Canals: A Case Series  

PubMed Central

Thorough understanding of the anatomic and internal morphology of a root canal system is absolutely essential for the success of endodontic treatment. Since permanent maxillary first molars have shown variation in internal anatomy, morphology, this tooth has been reviewed extensively. Presence of two canals in a two-rooted maxillary first molar has rarely been reported in studies describing tooth and root canal anatomies. In this report, three cases are presented, which involve the root canal treatment of maxillary first molars with fusion of the two buccal roots.

Shakouie, Sahar; Mokhtari, Hadi; Ghasemi, Negin; Gholizadeh, Seddigheh

2013-01-01

179

A New Anatomically Based Nomenclature for the Roots and Root Canals--Part 2: Mandibular Molars  

PubMed Central

Several terminologies have been employed in the dental literature to describe the roots and root canal systems of mandibular molars with no consensus being arrived at, thus far. The anatomical relation of roots and their root canals were identified and a naming system was formulated. The proposed nomenclature attempts to make certain essential modifications to the traditional approach to accommodate the naming of various aberrations presented in mandibular molars. A simple, yet extensive nomenclature system has been proposed that appropriately names the internal and external morphology of mandibular molars.

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

2012-01-01

180

Evaluation of maxillary molar distalization with the distal jet: a comparison with other contemporary methods.  

PubMed

Maxillary molar distalization is an increasingly popular option for the resolution of Class II malocclusions. This communication describes the effects of one particular molar distalizing appliance, the distal jet, in a sample of 20 consecutively treated and growing subjects (11 females, nine males; mean starting age of 13) and compares these effects with those of similar devices. Pre- and postdistalization cephalometric radiographs and dental models were analyzed to determine the dental and skeletal effects. The distal jet appliances were constructed using a biomechanical couple to direct the distalizing force to the level of the maxillary first molar's center of resistance. The distal jet was the only appliance used during the distalization phase of treatment. Examination of the cephalometric tracings demonstrated that the crowns of the maxillary first molars were distalized an average of 3.2 mm into a Class I molar relationship. In the process, the first molars were tipped distally an average of 3.1 degrees, however, the amount of tipping in each case was influenced by the state of eruption of the second molar. In subjects whose second molars had erupted only to the level of the apical third of the first molar roots, distal tipping was almost twice that seen when the second molar had completed their eruption. Anchorage loss measured at the first premolars averaged 1.3 mm, but the crowns tipped 3.1 degrees distally because of the design of the appliance. The maxillary incisors were proclined an average of 0.6 degrees with minimal effect on the mandibular plane angle and lower facial height. This study suggests that the distal jet appliance effectively moves the maxillary molars distally into a Class I molar relationship with minimal distal tipping, however, some loss of anchorage is to be expected during this process. The distal jet appliance compares favorably with other intraoral distalization devices and with mechanics featuring mandibular protraction for the resolution of patients with Class II, despite the fact that these types of mechanics address different jaws. PMID:12401059

Bolla, Eugenio; Muratore, Filippo; Carano, Aldo; Bowman, S Jay

2002-10-01

181

The effectiveness of a single osteointegrated implant combined with pendulum springs for molar distalization.  

PubMed

The aim of this report was to present the clinical efficiency of a single osteointegrated implant combined with pendulum springs for molar distalization. A 15-year-old girl sought treatment for irregular anterior teeth and poor smile esthetics. A novel appliance was designed that combined osteointegrated implants with 0.032-in beta-titanium wire and pendulum springs. The treatment results were evaluated from lateral cephalometric radiographs. Distalization of the maxillary first molars was achieved in 6 months. Total treatment time was 21 months. Facial esthetics improved as a consequence of treatment. This appliance design offers reliable molar distalization, even when absolute anchorage is required. PMID:17276871

Onca?, Gökhan; Akyalçin, Sercan; Arikan, Fatih

2007-02-01

182

Standard molar enthalpies of formation of some trichloroanilines by rotating-bomb calorimetry  

Microsoft Academic Search

The standard ( po= 0.1 MPa) molar enthalpies of formation ?fHmo, at the temperature 298.15 K, for crystalline 2,3,4-, 2,4,5-, 2,4,6- and 3,4,5-trichloroaniline were derived from the molar enthalpies of combustion ?cHmoin oxygen using rotating bomb combustion calorimetry. The reaction products were CO2(g), N2(g), and HCl · 600H2O(l). The standard molar enthalpies of sublimation ?crgHmoat T= 298.15 K were measured

Ana I. M. C. L. Ferreira

2002-01-01

183

Radiographic evaluation of third molar genesis in Greek orthodontic patients  

PubMed Central

Objectives The study reported here investigated the first radiographic evidence of third molar (M3) formation, their incidence and distribution as well as their congenital absence on the right or the left side in either the maxilla or the mandible, in both male and female Greek orthodontic patients. Materials and methods A total of 618 panoramic radiographs were initially examined. After the application of inclusion/exclusion criteria, the group finally selected consisted of 428 patients (mean age 11.64 years, range 5–18): 179 males (mean age 11.73 ± 2.46) and 249 females (mean age 11.57 ± 2.45). The collected data were analyzed using SPSS software (IBM, Armonk, New York, NY, USA). The level of significance for all analyses was set to p = 0.05. The chi-square (?2) test was used to assess the relationships between variables. The Wilcoxon’s signed-rank test and the Mann-Whitney U test were also used for comparisons as well as the Spearman’s rho test for correlations. Results M3s were first detected in females at the age of 7 years whereas males followed one year later at the age of 8 years. A strong correlation between age and M3 development was revealed for both sexes (Spearman’s rho = 0.177, p = 0.05). Presence of all four M3s was the most common incidence (present in 70.8% of study subjects), followed by the agenesis of two (12.1%), agenesis of all four (8.4%), one (6.8%), and three (1.9%) M3s. Congenitally missing M3s in all subjects showed a significantly greater predilection for the maxilla over the mandible (19.6% and 15.5%, respectively) (Wilcoxon signed-rank test Z = ?2.404, p = 0.016). However, the distribution was found equal between the two sides of the jaws. The difference between the absent frequencies of M3s in the mandible and the maxilla was found statistically significant for the total sample (McNemar’s test, p < 0.001) and for males (p = 0.041) as well. Conclusion The study data may provide a reference for the M3 genesis in Greeks.

Barka, Georgia; Marathiotis, Konstantinos; Protogerakis, Michael; Zafeiriadis, Andreas

2013-01-01

184

Age at first molar emergence in early Miocene Afropithecus turkanensis and life-history evolution in the Hominoidea  

Microsoft Academic Search

Among primates, age at first molar emergence is correlated with a variety of life history traits. Age at first molar emergence can therefore be used to broadly infer the life histories of fossil primate species. One method of determining age at first molar emergence is to determine the age at death of fossil individuals that were in the process of

Jay Kelley; Tanya M. Smith

2003-01-01

185

Endodontic Treatment of a Mandibular Second Molar with Two Mesial Roots: Report of a Case  

PubMed Central

A case of unusual root morphology is presented to demonstrate anatomic variations in mandibular second molars. The most common configuration of mandibular second molar is to have two roots with three root canals; however mandibular molars may have many different combinations. Endodontic therapy was performed in a mandibular second molar with 3 separate roots 2 located mesially and one distally. Radiographically all 3 root canals terminated with individual foramina. Three orifices or 3 independent canals were found in the 3 separate roots, indicating a rare anatomic configuration. Looking for additional roots, canals and unusual morphology is an important part of successful endodontics as the knowledge of their existence occasionally enable clinicians to treat a case that otherwise might have ended in failure.

Ravanshad, Shohreh; Nabavizade, Mohammad Reza

2008-01-01

186

Endodontic Management of Mandibular First Molar with Middle Distal Canal: A Case Report  

PubMed Central

The knowledge of variations in root canal morphology is critical for a successful endodontic treatment. This article presents the endodontic management of a unique case of mandibular molar with middle distal canal which is quite uncommon.

Venumuddala, Vijay Reddy; Sridhar, M.; Rajasekaran, M.; Poorni, Saravanan; Senthilkumaran, Gnanaprakasam

2012-01-01

187

Use of the intraosseous screw for unilateral upper molar distalization and found well balanced occlusion  

PubMed Central

Background The aim of this study was to present a temporary anchorage device with intraosseous screw for unilateral molar distalization to make a space for the impacted premolar and to found well balanced occlusion in a case. Case presentation A 13-year-old male who have an impacted premolar is presented with skeletal Class I and dental Class 2 relationship. The screw was placed and immediately loaded to distalize the left upper first and second molar. The average distalization time to achieve an overcorrected Class I molar relationship was 3.6 months. There was no change in overjet, overbite, or mandibular plane angle measurements. Mild protrusion (0.5 mm) of the upper left central incisor was also recorded. Conclusion Immediately loaded intraosseous screw-supported anchorage unit was successful in achieving sufficient unilateral molar distalization without anchorage loss. This treatment procedure was an alternative treatment to the extraction therapy.

Gelgor, Ibrahim Erhan; Karaman, Ali Ihya; Buyukyilmaz, Tamer

2006-01-01

188

Autotransplantation of a mandibular third molar: a case report with 5 years of follow-up.  

PubMed

This paper describes the autologous transplantation of a mandibular right third molar to replace the residual roots of the second molar in the same quadrant, preserving function and aesthetics. A 5-year clinical and radiographic follow-up was undertaken. After transplantation, the donor tooth received endodontic treatment and placement of calcium hydroxide, which was periodically replaced every 3 months until the filling of the root canals, totalizing a period of 1-year, when apical closure was confirmed. The tooth was in perfect functional and aesthetic conditions 5 years after beginning of treatment. Autotransplantation is a feasible option for replacing missing teeth when a donor tooth is available. The autotransplantation of a right mandibular third molar with compromised function and aesthetics to replace the residual roots resulting from coronal destruction due to extensive carious lesion of the second molar in the same quadrant was a viable treatment alternative. PMID:23969922

Chagas e Silva, Mauro Henrique; Lacerda, Mariane Floriano Lopes Santos; Chaves, Maria das Graças Afonso Miranda; Campos, Celso Neiva

189

A rare presentation of dens in dente in the mandibular third molar with extra oral sinus.  

PubMed

The unusual case of dense in dente in mandibular molar area with extra oral sinus in a 30-year-old female is presented. The chief complaint of the patient was wound formation and pus discharge from the right side of lower jaw for many years. Clinical examination revealed extra oral sinus and mild swelling in vestibular region opposite the right mandibular molars. On radiographical examination, right mandibular third molar had bulbous root associated with periapical radiolucency. It appeared that there was a tooth within a tooth and the invagination extended nearly to the root apex. A clinical diagnosis of dense in dente Type III was confirmed by stereomicroscopy of ground section of the tooth. Extra oral sinus healed after extraction of the mandibular third molar within a month. PMID:21731269

Bansal, Monika; Singh, Nn; Singh, Anand Pratap

2010-07-01

190

Maxillary molar distalization: Pendulum and FastBack, comparison between two approaches for Class II malocclusion  

Microsoft Academic Search

ObjectivesTo compare the dento-alveolar and skeletal effects produced by two different molar intraoral distalization appliances, Pendulum and Fast-Back, both followed by fixed appliances, in the treatment of Class II malocclusion.

Alberto Caprioglio; Matteo Beretta; Claudio Lanteri

2011-01-01

191

How Many Digits Should We Use in Formula or Molar Mass Calculations?  

ERIC Educational Resources Information Center

|The calculations of uncertainties in the formula or molar masses of compounds are streamlined. Three rules of increasing complexity are proposed, which overestimate the uncertainty so there is little if any risk that the true values are missed.|

Svensson, Christer

2004-01-01

192

Crown components of mandibular molar teeth in 45,X females (Turner syndrome)  

Microsoft Academic Search

This study was designed to determine the possible effect of one X-chromosome constitution on components of the human permanent and primary molar teeth. Enamel, dentine, pulp and crown dimensions were measured on radiographs of first and second permanent and second primary mandibular molars of 49 Finnish 45,X females (Turner syndrome), their 46 first-degree male and female relatives and 50 non-related

U. Zilberman; P. Smith; L. Alvesalo

2000-01-01

193

Endodontic management of permanent mandibular left first molar with six root canals.  

PubMed

The endodontic treatment of a mandibular molar with aberrant canal configuration can be diagnostically and clinically challenging. This case report presents the treatment of a mandibular first molar with six root canals, of which three canals were located in the mesial root and three in distal root. Third canals were found between the two main root canals. This case presents a rare anatomic configuration and points to the importance of expecting and searching for additional canals. PMID:22629055

Gupta, Sachin; Jaiswal, Shikha; Arora, Rohit

2012-04-01

194

Agenesis of premolar associated with submerged primary molar and a supernumerary premolar: An unusual case report  

PubMed Central

The combination of submerged primary molar, agenesis of permanent successor with a supernumerary in the same place is very rare. The purpose of this article is to report a case of submerged mandibular left second primary molar with supernumerary tooth in the same region along with agenesis of second premolar in an 11-year-old girl, its possible etiological factors, and a brief discussion on treatment options.

Nirmala, S. V. S. G.; Sandeep, C.; Sivakumar, N.; Babu, M. S.; Lalitha, V.

2012-01-01

195

Optimization of the mineral content in polymeric gels: The effect of calcium to phosphate molar ratio  

Microsoft Academic Search

The influence of calcium to phosphate (Ca\\/P) molar ratio on the extent of mineralization in a model (poly)acrylamide gel was investigated under simulated physiological conditions. We hypothesized that the optimal growth of hydroxyapatite crystals will take place at the stoichiometric Ca\\/P molar ratio of 1.67. Phosphate ions were incorporated during the polymerization of the gel and mineralization was initiated by

Prasenjit Das; Ozan Akkus; Abdul-Majeed Azad

2005-01-01

196

Multicenter Retrospective Analysis of Wide-Neck Dental Implants for Single Molar Replacement  

Microsoft Academic Search

Purpose: To evaluate the predictability of Straumann wide-neck dental implants (6.5-mm prosthetic neck with a 4.8-mm endosseous sandblasted, large-grit, acid-etched-surface body) used for molar replacement. Materials and Methods: Four hundred ninety-nine single-tooth implants were restored in molar sites in 410 patients (mean time of loading 23 months; range, 1 to 54 months) by 6 clinicians throughout the United States. Three

Robert A. Levine; Jeffrey Ganeles; Robert A. Jaffin; Donald S. Clem; Jay R. Beagle; G. William Keller

197

Root and canal morphology of permanent mandibular molars in a Sri Lankan population  

Microsoft Academic Search

The main purpose of this study was to investigate the root and canal morphology of Sri Lankan mandibular molars and to determine\\u000a the affinities of these morphological variations to those of people of European and Asian origin. Two hundred mandibular first\\u000a and second molars were examined. The number of roots and the prevalence of C-shaped (gutter-shaped) roots in mandibular second

Roshan Peiris; Masami Takahashi; Kayoko Sasaki; Eisaku Kanazawa

2007-01-01

198

Cephalometric comparison of maxillary second molar extraction and nonextraction treatments in patients with Class II malocclusions  

Microsoft Academic Search

This retrospective cephalometric study compared the nature of the skeletodental correction of maxillary second-molar extraction and nonextraction treatments in correcting Class II malocclusions. The sample comprised 50 Class II, deep-bite, low-angle adolescents; half were treated with maxillary second-molar extraction and half were treated without extraction. Pretreatment and posttreatment lateral cephalograms were analyzed. Analysis relied primarily on the method of Lysle

Donihue Waters; Edward F. Harris

2001-01-01

199

Standard molar enthalpy of formation of 4-iodobenzoic acid by static and rotating-bomb calorimetry  

Microsoft Academic Search

The standard (po= 0.1 MPa) molar enthalpy of combustion of 4-iodobenzoic acid, at T= 298.15 K, was measured by static-bomb and rotating-bomb calorimetry, from which the standard molar enthalpy of formation, in the crystalline state, was derived.The values obtained confirm that 4-iodobenzoic acid is a satisfactory test substance for combustion of organo-iodine compounds. Using a literature value for its standard

M. A. V. Ribeiro da Silva; M. L. C. C. H. Ferrão; I. M. S. Costa

1999-01-01

200

A reassessment of the molar volume of silicon and of the Avogadro constant  

Microsoft Academic Search

An “absolute” value for the molar volume of Si in Si single crystals is presented as 12.058 820 7(54) cm3 mol-1 with a relative standard uncertainty of 4.5·10 -7. It is argued that the consistency of most of the molar volume determinations is useful for evaluating the quality of the Si single crystals involved. A value for the Avogadro constant

Paul De Bièvre; Staf Valkiers; Rüdiger Kessel; Philip D. P. Taylor; Peter Becker; H. Bettin; Anna Peuto; Savino Pettorruso; K. Fujii; A. Waseda; M. Tanaka; R. D. Deslattes; H. S. Peiser; M. J. Kenny

2001-01-01

201

Asymmetrical growth, differential cell proliferation, and dynamic cell rearrangement underlie epithelial morphogenesis in mouse molar development  

Microsoft Academic Search

During molar development from the cap to bell stage, the morphology of the enamel knots, inner dental epithelium, and epithelial-mesenchymal\\u000a junction dynamically changes, leading to the formation of multiple cusps. To study the basic histological features of this\\u000a morphogenetic change, we have investigated the cell arrangement, mitosis, and apoptosis simultaneously in the developing first\\u000a lower molar of the mouse by

Nobuko Obara; Hervé Lesot

2007-01-01

202

Sharp mandibular bone irregularities after lower third molar extraction: Incidence, clinical features and risk factors  

PubMed Central

Objectives: The purpose of this study was to determine the incidence and clinical symptoms associated with sharp mandibular bone irregularities (SMBI) after lower third molar extraction and to identify possible risk factors for this complication. Study Design: A mixed study design was used. A retrospective cohort study of 1432 lower third molar extractions was done to determine the incidence of SMBI and a retrospective case-control study was done to determine potential demographic and etiologic factors by comparing those patients with postoperative SMBI with controls. Results: Twelve SMBI were found (0.84%). Age was the most important risk factor for this complication. The operated side and the presence of an associated radiolucent image were also significantly related to the development of mandibular bone irregularities. The depth of impaction of the tooth might also be an important factor since erupted or nearly erupted third molars were more frequent in the SMBI group. Conclusions: SMBI are a rare postoperative complication after lower third molar removal. Older patients having left side lower third molars removed are more likely to develop this problem. The treatment should be the removal of the irregularity when the patient is symptomatic. Key words:Third molar, postoperative complication, bone irregularities, age.

Alves-Pereira, Daniela; Valmaseda-Castellon, Eduard; Laskin, Daniel M.; Berini-Aytes, Leonardo; Gay-Escoda, Cosme

2013-01-01

203

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

204

Molar-incisor hypomineralisation: prevalence and defect characteristics in Iraqi children.  

PubMed

BACKGROUND.? Little prevalence data relating to molar incisor hypomineralisation (MIH) exist for Middle East populations. AIM.? To evaluate the prevalence and the clinical features of MIH in school-aged children residing in Mosul City, Iraq. DESIGN.? A cluster sample of 823 7- to 9-year-old children had their first permanent molars and incisors (index teeth) evaluated using the European Academy of Paediatric Dentistry (EAPD) criteria for MIH. The examinations were conducted at schools by a calibrated examiner. RESULTS.? Of the children examined, 177 (21.5%) had hypomineralisation defects in at least one index tooth, 153 (18.6%) had at least one affected first molar or first molars and incisors and were considered as having MIH. The most commonly affected teeth were maxillary molars. Demarcated creamy white opacities were the most frequent lesion type. Dental restorations and tooth extraction because of MIH were uncommon. Children with three or more affected teeth were 3.7 times more likely to have enamel breakdown when compared with those children having only one or two affected teeth. CONCLUSIONS.? Molar incisor hypomineralisation was common amongst Iraqi children. Demarcated opacities were more prevalent than breakdown. The severity of the lesions increased with the number of affected teeth. The more severe the defect, the greater the involved tooth surface area. PMID:21689174

Ghanim, Aghareed; Morgan, Michael; Mariño, Rodrigo; Bailey, Denise; Manton, David

2011-06-20

205

Conventional root canal therapy of C-shaped mandibular second molar. A case report.  

PubMed

The C-shaped root canal system and treatment implications were first described by Cooke and Cox in 1979. C-shaped canals are most frequently found in mandibular second molars, but they can occur in any mandibular molar, and they have been reported in maxillary molars as well. C-shaped mandibular molars are characterized by a C-shaped groove that connects one or more root canals. This groove can occur anywhere along the root canal system, making it difficult to diagnose and treat. A C-shaped root canal system may appear completely normal at the level of the pulp chamber but can begin to manifest itself in the middle or apical one-third. Furthermore, C-shaped canals are challenging if not impossible to predict radiographically. C-shaped canals in mandibular second molars are found most frequently in the Chinese population, with reports showing up to a 31.5% incidence, as compared to an approximate 7% incidence in the general population. This case report demonstrates an incidence of a C-shaped canal that was unable to be detected radiographically and which contained three separate root canals that communicated in the apical one-third of the root canal system. Canal orifices were located approximately 2 mm below the level of the CEJ, which is in agreement with a recent micro-computed tomography study of C-shaped mandibular molars that found 98% of all C-shaped molars studied had orifices located 1 mm to 3 mm below the CEJ. The CT study also found that all C-shaped canals contained fused roots and confirmed previous findings that the C-shape configuration varies greatly throughout the length of the canal. PMID:17203853

Lynn, Evan A

2006-11-01

206

Ectopic third molar in the mandibular condyle: A review of the literature  

PubMed Central

Objectives: To evaluate the etiopathogenesis, clinical features, therapeutic options, and surgical approaches for removal of ectopic third molars in the mandibular condyle. Study design: MEDLINE search of articles published on ectopic third molars in the mandibular condyle from 1980 to 2011. 14 well-documented clinical cases from the literature were evaluated together with a new clinical case provided by the authors, representing a sample of 15 patients. Results: We found a mean age at diagnosis of 48.6 years and a higher prevalence in women. In 14 patients, associated radiolucent lesions were diagnosed on radiographic studies and confirmed histopathologically as odontogenic cysts. Clinical symptoms were pain and swelling in the jaw or preauricular region, trismus, difficulty chewing, cutaneous fistula and temporomandibular joint dysfunction. Treatment included conservative management in one case and in the other cases, surgical removal by intra- or extraoral approaches, the latter being the most common approach carried out. In most reported cases, serious complications were not outlined. Conclusions: The etiopathogenic theory involving odontogenic cysts in the displacement of third molars to the mandibular condyle seems to be the most relevant. They must be removed if they cause symptoms or are associated with cystic pathology. The surgical route must be planned according to the location and position of the ectopic third molar, and the possible morbidity associated with surgery. Key words:Third molar, ectopic tooth, condyle, mandible.

Iglesias-Martin, Fernando; Torres-Carranza, Eusebio; Prats-Golczer, Victoria-Eugenia; Garcia-Perla-Garcia, Alberto

2012-01-01

207

An evaluation of third molar eruption for assessment of chronologic age: A panoramic study  

PubMed Central

Objectives: The identity of a person can be established by assessing one's age, and in order to be entitled to civil rights and social benefits, verification of the chronological age is required and thereby age estimation has gained an increasing significance in recent years. Tooth eruption is one of the criteria of developmental morphology that can be evaluated by either clinical examination or by evaluation of dental radiographs to determine the dental age. The present study was aimed to evaluate the reliability of the third molar eruption stage as a parameter for forensic age estimation in living subjects. Materials and Methods: The stage of wisdom tooth eruption in 77 male and 73 female Indian subjects aged between 12–26 years was determined by subjecting them to conventional orthopantomograms and was interpreted to assess the third molar eruption stages to evaluate the dental age. Results: Predicted minimum age and mean age of the study sample were found to be significant predictors (P<0.001) of actual age. Minimum age was able to explain 58.3% of the variation in actual age and the mean age was able to explain 60.3% of variation in actual age. Conclusion: Third molar is fairly a reliable indicator to determine the age of alveolar, gingival, and complete emergence of third molar in the occlusal plane in adolescents and young adults. Minimum and most probable ages of examined subjects can also be evaluated using third molar eruption stage.

Tuteja, Monica; Bahirwani, Shraddha; Balaji, P

2012-01-01

208

The prognosis of retained primary molars without successors: infraocclusion, root resorption and restorations in 111 patients.  

PubMed

This study aimed to assess infraocclusion, root resorption and restorations and their importance for the prognosis of retained primary mandibular molars lacking successors. The sample comprised 188 persisting primary mandibular second molars in 111 subjects, 48 males and 63 females, with a mean age of 12.6 years. The patients had been referred to an interdisciplinary clinic because of extensive hypodontia, missing 8.4 teeth on average. All persisting primary mandibular molars were included in the study, as no decision had been made as to whether they should be kept or extracted. Panoramic radiographs were used to assess infraocclusion, resorption of the mesial and distal roots and whether restorations were present.Clinically significant infraocclusion was observed in 43.6 per cent of the patients and classified as severe in 18.8 per cent. The mesial and distal root exhibited no resorption in 18.9 and 33.3 per cent, respectively (P = 0.01). Most primary molars had no restorations (78.4 per cent). A significant correlation was found between root resorption and infraocclusion. Age was found to be weakly but significantly correlated with root resorption and infraocclusion. No significant relationship was observed between gender and either infraocclusion or root resorption.In conclusion, infraocclusion was estimated to be a more critical factor for the prognosis of retained primary molars than root resorption. PMID:23314329

Hvaring, Christina L; Ogaard, Bjørn; Stenvik, Arild; Birkeland, Kari

2013-01-12

209

Natural selection on molar size in a wild population of howler monkeys (Alouatta palliata).  

PubMed Central

Dental traits have long been assumed to be under selection in mammals, based on the macroevolutionary correlation between dental morphology and feeding behaviour. However, natural selection acting on dental morphology has rarely, if ever, been documented in wild populations. We investigated the possibility of microevolutionary selection on dental traits by measuring molar breadth in a sample of Alouatta palliata (mantled howler monkey) crania from Barro Colorado Island (BCI), Panama. The age at death of the monkeys is an indicator of their fitness, since they were all found dead of natural causes. Howlers with small molars have significantly decreased fitness as they die, on average, at an earlier age (well before sexual maturity) than those with larger molars. This documents the existence of phenotypic viability selection on molar tooth size in the BCI howlers, regardless of causality or heritability. The selection is further shown to occur during the weaning phase of A. palliata life history, establishing a link between this period of increased mortality and selection on a specific morphological feature. These results provide initial empirical support for the long-held assumption that primate molar size is under natural selection.

DeGusta, David; Everett, Melanie A; Milton, Katharine

2003-01-01

210

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.

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

2013-01-01

211

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

212

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.

Hassan, Ali H.

2010-01-01

213

A Histologic Study of the Width and Nature of Inter-radicular Spaces in Human Adult Pre-molars and Molars  

Microsoft Academic Search

Serial sections of jaw segments from a human post mortem population of 29 individuals providing 116 posterior interproximal sites were examined at the light microscopic level. Minimum inter-root distances at the locale of closest proximity ranged from more than 4 mm to less than 0.1 mm. They were located in the coronal third of pre-molars and mandibular first and second

P. J. Heins; S. M. Wieder

1986-01-01

214

Radix Entomolaris in Mandibular First Molars in Indian Population: A Review and Case Reports  

PubMed Central

Purpose. The aim of this paper is to present cases of mandibular first molars with an additional distolingual root and their management using appropriate instruments and techniques. Basic Procedures and Main Findings. Mandibular molars can sometimes present a variation called radix entomolaris, wherein the tooth has an extra root attached to its lingual aspect. This additional root may complicate the endodontic management of the tooth if it is misdiagnosed or maltreated. This paper reviews the prevalence of such cases in Indian population and reports the management of 6 such teeth. Principal Conclusions. (1) It is crucial to be familiar with variations in tooth/canal anatomy and characteristic features since such knowledge can aid location and negotiation of canals, as well as their subsequent management. (2) Accurate diagnosis and careful application of clinical endodontic skill can favorably alter the prognosis of mandibular molars with this root morphology.

Attam, Kanika; Nawal, Ruchika Roongta; Utneja, Shivani; Talwar, Sangeeta

2012-01-01

215

Long-term follow-up on C-shaped mandibular molars.  

PubMed

Three cases of mandibular second molars with C-shaped root canal morphology are described. Two of these molars did not radiographically show the usual anatomic configuration of two separated roots, but rather had a single conical root. Only two root canals orifices were observed in the pulp chamber floor: a mesial-lingual orifice in its normal position and a buccal C-shaped fissure that was continuous from the normal location of the mesiobuccal canal to that of the distal canal. The fissure became smaller in the apical third, ending in a distal direction. The third case, a second molar extracted because of severe periodontal involvement showed, after sectioning, a C-shaped root with connections between all three canals. PMID:8935017

Ricucci, D; Pascon, E A; Langeland, K

1996-04-01

216

An evaluation of intraoral molar distalization with nickel-titanium coil springs.  

PubMed

The purpose of this study was to determine dental and skeletal effects of compressed nickel-titanium coil springs used for distal movement of the maxillary molars. Initial and follow-up cephalometric radiographs were taken of 8 patients (2 males and 6 females) in the late mixed or permanent dentition stage with Class II malocclusion. Nickel-titanium coil springs exerting a near constant force of approximately 250 g were compressed against the maxillary molar tubes by Gurin locks. The mean treatment time was 6.95 +/- 0.2 months. Dental and skeletal changes were determined as follows: The mean maxillary first molar distalization was 5.44 mm (right) and 3.75 mm (left), with a mesial tipping of 11.56 degrees (right) and 11.34 degrees (left). Anchorage loss occurred as defined by mesial movement of the first premolars and proclination of the central incisors. Vertical dental and skeletal dimensions were not affected. PMID:16163876

Oztürk, Yildiz; Firatli, Sonmez; Almaç, Levent

2005-10-01

217

[Could the distalization of the mandibular molars be facilitated? A new therapeutic method].  

PubMed

A young patient complained of missing inferior second premolars. Clinical and cephalometric parameters suggested the indication for a prosthetic solution, opening the spaces between first premolars and molars, aiming to correct occlusal relationships. Space closure was thus excluded. After full arch alignment a selective conservative channel-like wedge shaped osteotomy, distal to the second molars, was performed, applying a piezo-microsurgery technique, which uses fine inserts (0.5-0.7 mm) and ultrasound. The method allows for good patient compliance, improved rapid healing, and no secondary adverse effects. Both second and first molars can then be easily and rapidly distalized with a bodily movement, avoiding distal tipping. After space opening implants could be applied and the occlusion finalized. Though further tests will be needed, the method appears a valid improvement to conventional methods, facilitating distalization in selected cases and possibly shortening treatment time. PMID:19954734

Finotti, Marco; Del Torre, Mariarosa; Roberto, Michela; Miotti, Francesca A

2009-12-04

218

In-depth morphological study of mesiobuccal root canal systems in maxillary first molars: review  

PubMed Central

A common failure in endodontic treatment of the permanent maxillary first molars is likely to be caused by an inability to locate, clean, and obturate the second mesiobuccal (MB) canals. Because of the importance of knowledge on these additional canals, there have been numerous studies which investigated the maxillary first molar MB root canal morphology using in vivo and laboratory methods. In this article, the protocols, advantages and disadvantages of various methodologies for in-depth study of maxillary first molar MB root canal morphology were discussed. Furthermore, newly identified configuration types for the establishment of new classification system were suggested based on two image reformatting techniques of micro-computed tomography, which can be useful as a further 'Gold Standard' method for in-depth morphological study of complex root canal systems.

Chang, Seok-Woo; Lee, Jong-Ki; Lee, Yoon

2013-01-01

219

Changes in Apparent Molar Water Volume and DKP Solubility Yield Insights on the Hofmeister Effect  

PubMed Central

This study examines the properties of a 4 × 2 matrix of aqueous cations and anions at concentrations up to 8.0 M. The apparent molar water volume, as calculated by subtracting the mass and volume of the ions from the corresponding solution density, was found to exceed the molar volume of ice in many concentrated electrolyte solutions, underscoring the non-ideal behavior of these systems. The solvent properties of water were also analyzed by measuring the solubility of diketopiperazine (DKP) in 2.000 M salt solutions prepared from the same ion combinations. Solution rankings for DKP solubility were found to parallel the Hofmeister series for both cations and anions, whereas molar water volume concurred with the cation series only. The results are discussed within the framework of a desolvation energy model that attributes solute-specific changes in equilibria to solute-dependent changes in the free energy of bulk water.

Payumo, Alexander Y.; Huijon, R. Michael; Mansfield, Deauna D.; Belk, Laurel M.; Bui, Annie K.; Knight, Anne E.; Eggers, Daryl K.

2011-01-01

220

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

221

Three-rooted mandibular first molar: A consideration in periodontal therapy.  

PubMed

A deep understanding of the relationship between root morphology and periodontal destruction is crucial to successful periodontal care. Most mandibular molars have two roots (one mesial and the other distal) and three canals. The major variant of this tooth type is the presence of an additional third root distally or mesially or a supernumerary lingual root. This article presents a case report of a 14-year-old girl with mandibular first molar having three roots bilaterally which is contributing to the periodontal destruction. There were three walled defect distal to first molar with Grade II furcation involvement distally. Regenerative surgeries were performed and patient was kept under maintenance. The relationship between additional third root and periodontal destruction seldom has been described clearly. This paper has been presented in 34(th) national conference at Dharwad. PMID:23055602

Sachdeva, Shivani; Phadnaik, Mangesh B

2012-04-01

222

Modified lingual split technique for extraction of impacted mandibular third molars.  

PubMed

Critical evaluation of existing chisel and bur techniques for removal of impacted mandibular third molars reveals a high incidence of complications. Both approaches require creation of a buccal defect immediately distal to the second molar for the insertion of an elevator, which may cause pocketing to occur postoperatively. The method described here minimizes periosteal reflection, almost completely avoids loss of bone, and effectively reduces the use of rotary instrumentation. The planning of the soft tissue flaps and bony cuts assists in primary wound closure, obliteration of dead space, and reduction of postoperative morbidity. PMID:6930459

Lewis, J E

1980-08-01

223

Apparent Molar Volume and Viscosity Studies on Some Carbohydrates in Solutions  

Microsoft Academic Search

Summary.  ?The apparent molar volume (?v) and viscosity (?) of L(+)-arabinose, D(+)-galactose, D(?)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function\\u000a of solute concentrations at 308.15, 313.15, and 323.15?K, respectively. The apparent molar volume (?v) of the carbohydrates was found to be a linear function of the concentration. From

Parimal C. Dey; Muhammad A. Motin; Tapan K. Biswas; Entazul M. Huque

2003-01-01

224

The Mandibular First Molar with Three Canals in the Mesial Root- A Case Report  

PubMed Central

The dynamic concept of the root canal system, which describes a variable morphology of the multiple root canals which are inter-connected by anastomoses, has been established as the prevailing state in the mandibular molars. The aim of this case report was to describe the unusual root canal anatomy that was detected in the mandibular first molar during the routine endodontic treatment. The clinical and the radiographic examinations allowed the detection of the middle mesial root canal between the mesiobuccal and the mesiolingual root canals. This report highlights the importance of such examinations and the need to find and treat the additional canals, to achieve a successful endodontic treatment.

Deepalakshmi, Mohanavelu; Anupama, Ramachandran; Khan, Hidayathulla Sulthan Ibrahim Raja; Kumar, Kumarappan Senthil

2013-01-01

225

Nonsurgical Endodontic Retreatment of Maxillary Second Molar with Two Palatal Root Canals: A Case Report  

PubMed Central

Successful endodontic treatment requires thorough knowledge regarding each root canal system of any tooth and probability of extra canals should be considered. Second maxillary molar with two palatal root canals is not frequent and its incidence reported in literatures is about 0.4–2%. The present case report describes non-surgical retreatment of maxillary second mo-lar with two palatal root canals. Radiographic interpretation is difficult in this region; so, very careful examination of pulpal space and using supportive devices such as loupe and operating microscope is recommended to discover any unusual anat-omic features like extra canals.

Eskandarinezhad, Mahsa; Ghasemi, Negin

2012-01-01

226

Unilateral distal molar movement with an implant-supported distal jet appliance.  

PubMed

With the guidance of the basis of the distal jet appliance, we present a new implant-supported distal jet appliance. In this case, we used a modified distal jet appliance that was supported by a palatal implant placed at the anterior edge of the rugae region of the palate for molar distalization. The treatment results were evaluated from lateral cephalometric and panoramic radiographs and dental casts. We conclude that an implant-supported modified distal jet appliance is effective in the correction of a Class II molar relationship. PMID:11999940

Karaman, A I; Basciftci, F A; Polat, O

2002-04-01

227

Long-Term Clinical Performance of Aesthetic Restorations in Primary Molars: A Case Report  

PubMed Central

There is a great diversity of restorative materials and techniques for deciduous molars with significant coronal destruction, including resin composite restorations and biologic restorations (portions of natural teeth). By using 4 evaluation methods, this study aimed at longitudinally evaluating the effectiveness of restorations in the deciduous molars of a patient having high caries activity, using adhesive techniques. The evaluation methods consisted of the fibre-optic transillumination method, clinical evaluation based on the United States Public Health Service criteria, radiographs, and an indirect method, scanning electron microscopy. Despite the patient's poor biofilm control, the restorative techniques were shown to be efficacious, particularly the biologic restorative technique.

Pomarico, Luciana; Neves, Beatriz Goncalves; Maia, Lucianne Cople; Primo, Laura Guimaraes

2011-01-01

228

Measurement equations for the determination of the Si molar mass by isotope dilution mass spectrometry  

NASA Astrophysics Data System (ADS)

A new method applying isotope dilution mass spectrometry to determine the molar mass of a silicon sample, highly enriched with respect to 28Si, has been proposed recently. This paper describes a different way of calculating the molar mass by solving an equation linking the measurement results to the ratio between the amount-of-substance fractions of 28Si and 30Si in the sample. The mathematical model and the final measurement equation are much more straightforward than those previously reported, though fully equivalent.

Mana, G.; Rienitz, O.; Pramann, A.

2010-08-01

229

Size relationships among permanent mandibular molars in Aboriginal Australians and Papua New Guinea Highlanders.  

PubMed

Size relationships among crown units of permanent mandibular molars were investigated in two Sahul-Pacific samples: Aboriginal Australians (Yuendumu) and Papua New Guinea Highlanders (Wabag). Measurements of first, second, and third molars (M1, M2, and M3), including overall mesiodistal and buccolingual diameters as well as the mesiodistal and buccolingual diameters of the trigonid and talonid, were obtained from dental casts using a sliding caliper. Molar reduction was noted in talonid dimensions within both samples, but the trigonid mesiodistal diameter was not reduced in M2 or M3 compared with M1, indicating that the later-developing crown unit (talonid) was more reduced than the early-developing unit (trigonid). M2 was most reduced in size mesiodistally of the three molars, but its buccolingual diameter was not reduced. M3 was the most reduced tooth in trigonid buccolingual diameter. The percentage sexual dimorphism values were greater for the size of the talonid than for the trigonid, indicating that male values exceeded those for females by a greater amount in the later-developing crown unit. Crown dimensions were larger generally in the Aboriginal Australians from Yuendumu than in the Papua New Guinea Highlanders from Wabag, with differences being more evident in M2 and M3 than M1, especially in talonid dimensions. The trigonid, which develops early both phylogenetically and ontogenetically, tended to be relatively stable in size, whereas the later-forming talonid displayed size reduction when comparisons were made both within and between groups. PMID:16136541

Kondo, Shintaro; Townsend, Grant C; Kanazawa, Eisaku

230

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

231

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

232

Structure–properties relationship for resols with different formaldehyde\\/phenol molar ratio  

Microsoft Academic Search

The relationship between the structure and the viscoelastic properties of resol resins was studied. Six phenolic resins (resol) were synthesized with different molar ratios of formaldehyde to phenol. These resols were cured by means of temperature and without catalyst. The characterization of the resol was done by means of infrared spectroscopy and chemical methods. From the viscoelastic properties of fully

L. B. Manfredi; O. de la Osa; N. Galego Fernández; A. Vázquez

1999-01-01

233

Dentoskeletal effects induced by rapid molar distalization with the first class appliance  

Microsoft Academic Search

The purpose of this study was to evaluate the treatment effects of the first class appliance (FCA; Leone, Firenze, Italy), a new intraoral device for unilateral or bilateral rapid molar distalizaton. A retrospective study was conducted to compare the predistalization and postdistalization cephalograms of 17 patients (10 male, 7 female) with Class II malocclusions treated with the FCA. Mean age

Arturo Fortini; Massimo Lupoli; Fabio Giuntoli; Lorenzo Franchi

2004-01-01

234

Multipotent cells from the human third molar: feasibility of cell-based therapy for liver disease  

Microsoft Academic Search

Adult stem cells have been reported to exist in various tissues. The isolation of high-quality human stem cells that can be used for regeneration of fatal deseases from accessible resources is an important advance in stem cell research. In the present study, we identified a novel stem cell, which we named tooth germ progenitor cells (TGPCs), from discarded third molar,

Etsuko Ikeda; Kiyohito Yagi; Midori Kojima; Takahiro Yagyuu; Akira Ohshima; Satoshi Sobajima; Mika Tadokoro; Yoshihiro Katsube; Katsuhiro Isoda; Masuo Kondoh; Masaya Kawase; Masahiro J Go; Hisashi Adachi; Yukiharu Yokota; Tadaaki Kirita; Hajime Ohgushi

2008-01-01

235

Age-Specific Angulation of Unerupted Human Third Molar Teeth in a Cross-Sectional Sample.  

National Technical Information Service (NTIS)

For males aged 18 to 21, the angulation of unerupted third molars was unrelated to age. A counterbalancing loss of data resulting from tooth eruption and extraction accounted for this null finding. The value of age-specific angulation in determining wheth...

M. E. Cohen R. G. Walter J. J. Hyman P. K. Tombasco

1985-01-01

236

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

Microsoft Academic Search

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

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

2010-01-01

237

Summary of: Pulpotomy of human primary molars with MTA and Portland cement: a randomised controlled trial  

Microsoft Academic Search

Objective This study compared the clinical and radiographic effectiveness of mineral trioxide aggregate (MTA) and Portland cement (PC) as pulp dressing agents in carious primary teeth.Methodology Thirty carious primary mandibular molars of children aged 5-9 years old were randomly assigned to MTA or PC groups, and treated by a conventional pulpotomy technique. The teeth were restored with resin modified glass

M. Duggal

2009-01-01

238

Transforming Growth Factor-? Isoform Expression in Mature Human Healthy and Carious Molar Teeth  

Microsoft Academic Search

Transforming growth factor (TGF)- isoforms have been implicated in cellular signalling during tooth development and repair, but little is known of their cellular localisation or distribution within the dental tissues in the mature tooth. This study investigated the presence of TGF-1, 2 and 3 isoforms in tissues of sound and carious human molar teeth, to understand better the expression of

A. J. Sloan; H. Perry; J. B. Matthews; A. J. Smith

2000-01-01

239

Microchemical and structural regular variability of apatites in “overbuilt” enamel and dentin of human molar teeth  

Microsoft Academic Search

The aim of a recent paper was to recognize the chemical and structural changes in apatites, which form both the enamel and the dentin of the human tooth. The aim was achieved by scrutinizing the linear elemental profiles along the cross-sections of human molar teeth. Essentially, the task was accomplished with the application of the Electron Probe Microanalysis method and

A. Kuczumow; J. Nowak; R. Chalas

2011-01-01

240

Pulpotomy of human primary molars with MTA and Portland cement: a randomised controlled trial  

Microsoft Academic Search

Objective This study compared the clinical and radiographic effectiveness of mineral trioxide aggregate (MTA) and Portland cement (PC) as pulp dressing agents in carious primary teeth.Methodology Thirty carious primary mandibular molars of children aged 5-9 years old were randomly assigned to MTA or PC groups, and treated by a conventional pulpotomy technique. The teeth were restored with resin modified glass

A. B. S. Moretti; T. M. Oliveira; A. P. C. Fornetti; C. F. Santos; M. A. A. M. Machado; R. C. C. Abdo; V. T. Sakai

2009-01-01

241

Pulpotomías en molares primarios. Evaluación clínico radiográfica de formocresol o trióxido mineral agregado  

Microsoft Academic Search

Advances in Dentistry could not identify yet an ideal endodontic treatment showing high clinical success rates and allowing maintenance of deciduous molars until its normal exfoliation. Formocresol as a pulpo- tomy medicament has been, and continues being the most popular medication in spite of its local and sys- temic toxicity. The aim of this prospective study was to evaluate the

ANA M. BIONDI; SILVINA G. CORTESE; ANDREA ORTOLANI; CAROLINA BENCHUYA; MABEL TEDESCO

242

Unusual Root Canal Morphology of the Maxillary Second Molar: A Case Report  

PubMed Central

Introduction. This clinical case report presents the successful endodontic treatment of a maxillary second molar that has a mandibular molar-like anatomy with no palatal root and with each of its roots containing two separate root canals. Cone-beam computed tomography (CBCT) was used to confirm this unusual anatomy. Methods. A 34-year-old male patient was referred to the Department of Endodontics at Inonu University's Faculty of Dentistry because of severe pain in his right maxillary second molar. Clinical and radiographic examinations identified unusual roots and root canals anatomy, and CBCT was planned in order to understand the nature of these variations. Cleaning and shaping procedures were performed using the crown down technique with Sybron Endo (Glendora, CA, USA) rotary instruments, and endodontic treatment was completed with gutta-percha cones and AH Plus resin sealers using the cold lateral compaction technique. Conclusions. The maxillary second molar exhibits aberrations and variations in terms of the numbers and configurations of its roots and root canals, and CBCT can be a useful imaging technique in endodontics.

S?msek, Neslihan; Keles, Ali; Bulut, Elcin Tek?n

2013-01-01

243

Molar Tooth Sign in Joubert Syndrome: Clinical, Radiologic, and Pathologic Significance  

Microsoft Academic Search

Joubert syndrome is a rare autosomal-recessive condition characterized by early hyperpnea and apnea, developmental delay, and truncal ataxia. We previously described key ocular motor signs in Joubert syndrome and the molar tooth sign resulting from dysplasia of the isthmic segment of the brain stem, superior cerebellar peduncles, and vermis. In this study, we obtained clinical and developmental data in 61

Bernard L. Maria; Ronald G. Quisling; Louis C. Rosainz; Anthony T. Yachnis; Jill Gitten; Duane Dede; Eileen Fennell

1999-01-01

244

Anxiety Sensitivity as a Predictor of Anxiety and Pain Related to Third Molar Removal  

Microsoft Academic Search

PURPOSE: Anxiety sensitivity (AS) refers to the fear of anxiety-related symptoms resulting from beliefs that such sensations have negative somatic, social, or psychological consequences. The aim of the present study was to investigate whether AS can predict both anticipated and experienced pain and state and trait anxiety related to third molar removal. MATERIALS AND METHODS: Data were collected from 160

Arjen J. van Wijk; Ad de Jongh; Jerome A. Lindeboom

2010-01-01

245

Surface Ultrastructure of Rat Molar Teeth after Experimentally Induced Erosion and Attrition  

Microsoft Academic Search

Young Osborne-Mendel rats were given different diets for 6 weeks. Effects of soft and rough food as well as acidic sport drink on the lingual surfaces of first mandibular molars were studied. In addition, the effect of fluoride on erosion was examined. A Jeol JSM-35 scanning electron microscope was used to visualize tooth surface ultrastructure. Intact surfaces were found in

R. Sorvari; A. Pelttari; J. H. Meurman

1996-01-01

246

The MMP activity in developing rat molar roots and incisors demonstrated by in situ zymography  

Microsoft Academic Search

Matrix metalloproteinases (MMPs) have been expressed during root development and periodontal tissue formation, whereas it is not known if these MMP molecules are enzymatically active to degrade the extracellular matrices (ECMs). The present study was designed to investigate the gelatinolytic and collagenolytic activity in rat molar root and incisor development. Three-week old rat mandibles were frozen and cut without fixation

Ichiro Sakuraba; Junko Hatakeyama; Yuji Hatakeyama; Ichiro Takahashi; Hideaki Mayanagi; Yasuyuki Sasano

2006-01-01

247

Hemostasis and obliteration of mandibular arteriovenous malformation through direct hydroxyapatite cement injection into the molar cavity  

Microsoft Academic Search

A mandibular arteriovenous malformation (AVM) presented with massive molar socket bleeding and was emergently treated by tooth extraction and partial resection of the surrounding alveolar bone. To achieve hemostasis, the resultant cavity was filled with hydroxyapatite bone cement. Not only was hemostasis and alveolar reconstruction achieved, but follow-up angiography demonstrated venous outlet occlusion and retrograde AVM thrombosis requiring no further

Vicko Gluncic; Russell R Reid; Fuad M Baroody; Lawrence J Gottlieb; Sameer A Ansari

2010-01-01

248

Determination of the Molar Volume of Hydrogen from the Metal-Acid Reaction: An Experimental Alternative.  

ERIC Educational Resources Information Center

|Describes an alternative technique for determining the molar volume of hydrogen from the metal-acid reaction in which the metal sample is encased in a specially prepared cage and a pipette filler is used to fill an inverted burette with water. Eliminates some difficulties encountered with the conventional technique. (JRH)|

de Berg, Kevin; Chapman, Ken

1996-01-01

249

Dental Caries Area of Rat Molar Expanded by Cigarette Smoke Exposure  

Microsoft Academic Search

Objectives: Passive smoking is the involuntary inhalation of cigarette smoke (CS) and has an adverse impact on oral health. We examined the effect of CS exposure on caries risk and experimental dental caries. Methods: Experimental dental caries was induced in rat maxillary molars which were inoculated orally with Streptococcus mutans MT8148 and maintained on a cariogenic diet (diet 2000) and

Y. Fujinami; K. Nakano; O. Ueda; T. Ara; T. Hattori; T. Kawakami; P.-L. Wang

2011-01-01

250

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

251

Distal movement of mandibular molars in adult patients with the skeletal anchorage system  

Microsoft Academic Search

The skeletal anchorage system (SAS) consists of titanium anchor plates and monocortical screws that are temporarily placed in either the maxilla or the mandible, or in both, as absolute orthodontic anchorage units. Distalization of the molars has been one of the most difficult biomechanical problems in traditional orthodontics, particularly in adults and in the mandible. However, it has now become

Junji Sugawara; Takayoshi Daimaruya; Mikako Umemori; Hiroshi Nagasaka; Ichiro Takahashi; Hiroshi Kawamura; Hideo Mitani

2004-01-01

252

Size dependence of molar absorption coefficients of CdSe semiconductor quantum rods.  

PubMed

Fundamental properties: The molar absorption coefficients of CdSe quantum rods are determined experimentally as a function of their dimensions (see figure). Far above the band gap a simple dependence on volume is seen. The behavior at the band gap manifests a concentration of oscillator strength with decreased diameter in agreement with strong quantum confinement behavior. PMID:19347917

Shaviv, Ehud; Salant, Asaf; Banin, Uri

2009-05-11

253

Evidence-based Assessment: Evaluation of the Formocresol Versus Ferric Sulfate Primary Molar Pulpotomy  

Microsoft Academic Search

Purpose: Formocresol and ferric sulfate were evaluated as pulpotomy medicaments us- ing evidence-based dentistry principles. Formocresol has been challenged as a potential carcinogen and mutagen, leading to consideration of ferric sulfate. Methods: The PICOT statement was: (P) In human carious primary molars with revers- ible coronal pulpitis, (I) does a pulpotomy performed with ferric sulfate, (C) compared with formocresol, (O)

Alex Loh; Polly O'Hoy; Xuan Tran; Rachael Charles; Andrew Hughes; Kotaro Kubo; Louise Brearley Messer

2004-01-01

254

Biodiesel from Canola Oil using a 1:1 Molar Mixture of Methanol and Ethanol  

Technology Transfer Automated Retrieval System (TEKTRAN)

Canola oil was transesterified using an equimolar mixture of ethanol and methanol with potassium hydroxide (KOH) catalyst. Effect of catalyst concentration (0.5 to 1.5% wt/wt), molar ratio of equimolar mixture of ethanol and methanol (EMEM) to canola oil (3:1 to 12:1) and reaction temperature (25 t...

255

A comparative evaluation of the fracture strength of pulpotomized primary molars restored with various restorative materials.  

PubMed

Sixty extracted primary molars were used in the study. After pulpotomy, these were divided into four groups on the basis of restorative materials to be used. Results showed that the Ormocer had the maximum fracture strength while the posterior Glass Ionomer Cement showed the least fracture strength among the various restorative materials used in the study. PMID:17550039

Passi, Sidhi; Pandit, I K; Srivastava, Nikhil; Gugnani, Neeraj; Gupta, Monika

2007-01-01

256

ENDODONTIC TREATMENT OF A SECOND MAXILLARY MOLAR WITH FIVE ROOT CANALS - A CASE REPORT  

Microsoft Academic Search

ITRODUCTION: Knowledge of the internal dental morphology is a complex and extremely important point for planning and performing of endodontic treatment. CASE REPORT: The subject of this study was a clinical case of a second maxillary molar with five root canals - one canal in the palatal root, one canal in the distobuccal root and three canals in mesiobuccal root.

2009-01-01

257

Molar Mass Determinations for NA (Avogadro) Projects: Present Status and Potential for the Future  

Microsoft Academic Search

The present status of molar mass measurements of silicon is summarized because of their relevance to modern determinations of the Avogadro constant: principles of the measurement, measurement procedures and preparation of the synthetic isotope mixtures used to calibrate the measurements are described. Typical results are shown and the potential for improvements achievable in the near future is outlined.

P. DeBièvre; S. Valkiers

1994-01-01

258

Toward the Avogadro Constant - Preliminary Results on the Molar Volume of Silicon  

Microsoft Academic Search

The silicon molar volume has been measured through Atomic Weight and density measurements. Mass spectrometric determination of the isotopic composition was performed on two differently grown samples. Density of specimens from the same crystals was obtained through mass and direct dimension measurements on single crystal spheres.

A. Sacconi; A. Peuto; G. Lenaers; S. Valkiers; P. De Bievre

1988-01-01

259

Closing anterior open bites by intruding molars with titanium miniplate anchorage  

Microsoft Academic Search

The intent of this study was threefold: (1) to validate true intrusion of molars in adults, (2) to test the stability of miniplates as anchorage for intruding posterior teeth in the maxilla, and (3) to record the skeletal and dental changes of open-bite closure. Four adult patients who had anterior open-bite malocclusions were selected to undergo posterior intrusion with miniplate

Keith H. Sherwood; James G. Burch; William J. Thompson

2002-01-01

260

Molar-Ratio-Dependent Supramolecular Isomerism: Ag(I) Coordination Polymers with Bis(cyanobenzyl)sulfides.  

PubMed

The ratio is the key: On varying the molar ratio of the reactants, AgNO3 and tridentate m-L ligand, supramolecular isomers 1 and 2 comprising a 2D polymeric network were obtained. Conformational differences of m-L play a crucial role in the 2D network structures adopted for isomers 1 and 2. PMID:24014496

Lee, Eunji; Kim, Ja-Yeon; Lee, Shim Sung; Park, Ki-Min

2013-09-06

261

CO 2-clathrate destabilization: a new model of formation for molar tooth structures  

Microsoft Academic Search

Molar tooth structures (MT) are unusual and enigmatic, temporally restricted, calcite bleb- and sheet-like structures hosted almost exclusively in Mesoproterozoic and Neoproterozoic continental ramp and shelf carbonates. Characteristically, MT are sharply bounded, interconnected, often ptygmatically folded or broken structures filled with uniform fine blocky calcite, but with a distinct lack of detrital infill. Collectively, their sedimentological characteristics indicate that the

Dan Marshall; C. D. Anglin

2004-01-01

262

Evaluation of excess molar polarization in binary mixtures of Polar–Nonpolar liquids  

Microsoft Academic Search

Excess molar polarization in the binary mixture of polar solutes (acetic acid, n-tributyl phosphate) in nonpolar solvents (benzene, tetrachloromethane, p-xylene) is evaluated with the help of our proposed equation. The results have been compared with those obtained from a previously proposed equation. It is observed that our proposed equation is more accurate to interpret the liquid structure and molecular association

C. Dwivedy; S. K. Ray

2004-01-01

263

Molar crown formation in the Late Miocene Asian hominoids, Sivapithecus parvada and Sivapithecus indicus.  

PubMed

During the past decade, studies of enamel development have provided a broad temporal and geographic perspective on evolutionary developmental biology in Miocene hominoids. Here we report some of the first data for molar crown development in one hominoid genus, Sivapithecus. The data are compared to a range of extant and extinct hominoids. Crown formation times (CFTs), daily rates of enamel secretion (DSR), Retzius line number and periodicity, and relative enamel thickness (RET) were calculated in a mandibular first molar of Sivapithecus parvada and a maxillary first molar of Sivapithecus indicus from the Siwalik sequence of Pakistan. A CFT of 2.40 years for the protoconid of S. parvada and 2.25 years for the protocone of S. indicus lie within the range of first molar (M1) formation times for the majority of Miocene hominoids (1.96-2.40 years, excluding Proconsul heseloni), and are similar to an M(1) from Gorilla (2.31 years) and M(1)s from Pan (2.22-2.39 years). This is unlike the longer CFTs in modern humans, which appear to be linked with their extended growth period. In contrast to extant great apes and humans, daily rates of enamel secretion are rapid in the Sivapithecus M1s during the early stages of growth, which seems to be a common pattern for most Miocene apes. The rapid accumulation of cuspal enamel in the Sivapithecus molars produced thicker enamel than either Pan or Gorilla in a comparable period of time. Future studies on larger samples of living and fossil hominoids are needed to clarify trends in crown development, which may be better understood in the context of life history strategies coupled with good data on body mass and brain size. PMID:17512035

Mahoney, Patrick; Smith, Tanya M; Schwartz, Gary T; Dean, Christopher; Kelley, Jay

2007-05-23

264

Fluoride in Enamel Lining Pits and Fissures of the Occlusal Groove–Fossa System in Human Molar Teeth  

Microsoft Academic Search

The fluoride (F) distribution in enamel lining the occlusal fissures of human molars and premolars is difficult to investigate by normal microsampling techniques, yet this information is of importance as fissures are particularly susceptible to caries. We have used the proton probe to map the distribution of F and Ca in sections of 17 molar teeth collected from Danish and

E. I. F. Pearce; M. J. Larsen; G. E. Coote

1999-01-01

265

The effect of fiber insertion on fracture resistance of endodontically treated molars with MOD cavity and reattached fractured lingual cusps  

Microsoft Academic Search

In this study, the effect of flowable composite reinforced with a leno wave ultra high modulus (LWUHM) polyethylene fiber (Ribbond) on fracture resistance of endodonti- cally treated molars with MOD cavity and lingual cuspal fracture was evaluated. Sixty sound extracted human mandibular molars were randomly assigned to six groups (n 10). Group 1 served as control. Teeth in groups 2-

Sema Belli; Funda Kont Cobankara; O?uz Eraslan; Gürcan Eskitascioglu; Vistasp Karbhari

2006-01-01

266

Restoration of mechanical strength and morphological features of the periodontal ligament following orthodontic retention in the rat mandibular first molar  

Microsoft Academic Search

SUMMARY Biomechanical properties and morphological features of the periodontal ligament (PDL) in the rat mandibular molars were examined during orthodontic retention. Seventy-three male rats of the Wistar strain, 8 weeks of age, were used for biomechanical analysis and six rats for morphological analysis. An elastic band was inserted between the mandibular first and second molars for 4 days; after removal

Tadayoshi Fukui; Akira Yamane; Koichiro Komatsu; Mototsugu Chiba

267

Loss of molar occlusion and mandibular morphology in adults in an ancient human population consuming a coarse diet.  

PubMed

The purpose of the study is to investigate the link between number of molar teeth retained in occlusion and mandibular morphology in adults in an ancient, high dental wear human population. The study material comprises skeletons from Mediaeval Wharram Percy, England (N = 50 female, 69 male adults). It was hypothesized that adults retaining fewer occluding molars would show reduction in mandibular dimensions, particularly in the ascending ramus and gonial regions where the main muscles of mastication have their insertions. Molar occlusal status is assessed using the concept of functional units. Mandibular morphology is assessed using a suite of ten linear measurements plus the mandibular angle. Results show no evidence for any association between number of molars retained in occlusion and mandibular angle. There was an association between mandibular size and number of molars retained in occlusion, with smaller mandibular dimensions in those retaining fewer occluding molars. Some measurements were affected more than others so that there was also some shape alteration. Alteration of mandibular dimensions was more clearly demonstrable in females than in males. Only in females could significant reduction in the ascending ramus and gonial regions be demonstrated. Reasons for the apparent difference in response to loss of molar occlusion between male and female mandibles are unclear, but sex differences in bony metabolism mediated by hormonal factors may be implicated. Results suggest that care should be exercised when including mandibles from individuals showing loss of molar occlusion in morphological studies. Am J Phys Anthropol 152:383-392, 2013. © 2013 Wiley Periodicals, Inc. PMID:24104725

Mays, Simon A

2013-09-19

268

The influences of molar intrusion on the inferior alveolar neurovascular bundle and root using the skeletal anchorage system in dogs.  

PubMed

The skeletal anchorage system (SAS) was developed as intraoral rigid anchors for open-bite correction by intrusion of molars. Since the application of SAS is a new modality in orthodontic treatment, the influences of radical molar intrusion on the root and the inferior alveolar neurovascular bundle were unknown. The purpose of this research is to verify the effect of molar intrusion on the neurovascular bundle, the level of osseointegration of bone screws, and root resorption. The results of this study showed mandibular molars were intruded 3.4 mm on the average over 7 months in dogs. The miniplates were well stabilized with osseointegrated bone screws and the peri-implant soft tissues showed slight inflammatory changes. Neither nerves nor blood vessels were damaged. Root resorption was observed but was repaired with new cementum. We concluded that the SAS utilizing transmucosal titanium miniplates as an immovable orthodontic anchorage could provide a new modality for molar intrusions without serious iatrogenic problems. PMID:11211300

Daimaruya, T; Nagasaka, H; Umemori, M; Sugawara, J; Mitani, H

2001-02-01

269

A modified device for intraoral radiography to assess the distal osseous defects of mandibular second molar after impacted third molar surgery  

PubMed Central

Purpose This article is to describe a modified device for intraoral radiography which was developed to obtain reproducible radiographic images for assessment of distal osseous defects of the mandibular second molar (2 Mm) after impacted third molar (3 Mm) surgery. Materials and Methods A commercial available alignment system for posterior region was modified by adding a reference gauge pin (millimetric) and threading a hollow acrylic cylinder at the ring of the radiographic positioner to attach the X-ray collimator. The design included customized resin acrylic stent for the occlusal surface of the 2Mm in maximum intercuspal position, individualizing the biteblock positioner. Periapical radiographs were taken before and after surgical extraction of 3 Mm, employing the radiographic technique of parallelism described by Kugelberg (1986) with this modified film holder and inserting the gauge pin on the deepest bone probing depth point. Results This technique permitted to obtain standardized periapical radiographs with a moderate to high resolution, repeatability, and accuracy. There was no difference between the measurements on the pre- and post-operative radiographs. This technique allowed better maintenance of the same geometric position compared with conventional one. The insertion of the gauge pin provided the same reference point and localized the deepest osseous defect on the two-dimensional radiographs. Conclusion This technique allowed better reproducibility in posterior radiographic records (distal surface of 2 Mm) and more accurate measurements of radiographic bone level by the use of a millimetric pin.

Ana, Faria-Inocencio

2011-01-01

270

Crystallization behavior of bisphenol-A polycarbonate: Effects of crystallization time, temperature, and molar mass  

NASA Astrophysics Data System (ADS)

Crystallization and multiple melting behavior of bisphenol-A polycarbonate (PC) was investigated using differential scanning calorimetry (DSC) for the monitoring of thermal behavior and atomic force microscopy (AFM) for the morphology study. The exceedingly slow crystallization kinetics of PC and the feasibility of obtaining near monodisperse fractions provide distinct advantages for the elucidation of the effects of crystallization time, temperature, and molar mass on crystallization kinetics. The effects of molar mass on the glass transition temperature (T g) and heat capacity change at Tg, and the amorphous density of PC were investigated. Similar to many semicrystalline polymers, PC exhibits a multiple melting behavior upon heating. While for each PC sample, the coexistence of low and high temperature endothermic regions in the DSC heating traces is explained by the melting of populations of crystals with different stabilities, melting-recrystallization-remelting effects are observed only for the lowest molar mass samples. The effects of crystallization temperature and molar mass distribution on overall crystallization kinetics were studied for some of the fractions, including the commercial PC-28K (Mw = 28,000 g.mol-1 ) sample. Regarding the kinetics of secondary crystallization, particular attention was placed on understanding the effects of molar mass, initial degree of crystallinity prior to the secondary crystallization, and secondary crystallization time and temperature. The secondary crystallization of PC follows the same laws discovered in previous studies of PEEK, PET, it-PS and ethylene copolymers, and the results are discussed in the context of a bundle-like secondary crystallization model. During isothermal annealing of semicrystalline PC-28K around the high melting endotherm, a significant increase of melting temperature along with peak broadening with time was observed. Independently, morphological studies using AFM showed that mean lamellar thickness increases with time during isothermal annealing. These results are discussed in light of isothermal thickening of lamellar crystals. Lastly, almost 200 DSC melting traces of varying molar mass PC samples thermally treated under various conditions were analyzed to calculate crystallinity (Xc), rigid fraction (RF), and rigid amorphous fraction (RAF). The correlation between RAF vs Xc, Tg, and Tg broadening are discussed.

Sohn, Seungman

271

Computerized Tomography Technique for the Investigation of the Maxillary First Molar Mesiobuccal Root  

PubMed Central

The aim of this paper was to review the literature about the use of computerized tomography to evaluate the presence and characteristics of the second mesiobuccal canal in the maxillary first molar. An electronic search was performed. Frequencies of the presence of second mesiobuccal canal and root anatomy characteristics were extracted from the selected studies. Pooled frequencies were calculated as weighted means. Seven articles were included. A second mesiobuccal canal was present in 59.32% of the teeth, and it was noncommunicating in 58.45% of teeth presenting the canal itself. The most common root canal morphology was single canal or two separated canals. The present paper showed that cone beam CT is a viable radiologic device for the evaluation of the mesiobuccal root of maxillary first molars. In fact, it was observed that the frequency of second mesiobuccal canal detection is similar to those presented by clinical studies or micro-CT evaluations.

Del Fabbro, Massimo; Tsesis, Igor; Taschieri, Silvio

2013-01-01

272

Radiographic survey of third molar development in relation to chronological age among Japanese juveniles.  

PubMed

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 applied for further statistical analysis. Statistically significant differences were noted between the upper and lower jaws and genders. Accordingly, males achieved root developmental grades earlier than females. We assessed the mean ages for all formation grades and predicted the probability that a Japanese juvenile would be older than the relevant ages of 14, 16, and 20 as defined by Japanese Juvenile Law. We determined the likelihood that a Japanese youth is older than the relevant age of 18 as defined by legislation in the United States. PMID:15171172

Arany, Szilvia; Iino, Mitsuyoshi; Yoshioka, Naofumi

2004-05-01

273

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

2007-08-11

274

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.

Ulusoy, Ozgur Ilke Atasoy

2011-01-01

275

Durability of a polyacid-modified composite resin (compomer) in primary molars. A multicenter study.  

PubMed

A polyacid-modified composite resin (compomer) restorative material was evaluated in primary molars in a multicenter study. One hundred and fifty-nine class-II restorations were placed by 6 dentists in 79 children. The restorations were evaluated during a 2-year period, using slightly modified USPHS criteria. After 1 year 151 restorations were evaluated and, after 2 years, 104. The cumulative failure rate after 1 year was 8% and after 2 years, 22%. The main reasons for failure were loss of retention (12%) and secondary caries (5%). The compomer material showed a high failure rate, comparable to that of other adhesive restorative materials currently used in primary molars. A large operator variation in failure rate indicates the technique sensitivity of the material. PMID:9298168

Andersson-Wenckert, I E; Folkesson, U H; van Dijken, J W

1997-08-01

276

The standard molar enthalpy of formation of CdMoO4  

NASA Astrophysics Data System (ADS)

The molar enthalpies of solution of CdMoO4(s), CdO(s), Na2 MoO4(s) and NaF(s) in (10 mol HF(aq) + 4.41 mol H2O2(aq)) dm-3 have been measured using an isoperibol type calorimeter. From these results and other auxiliary data, the standard molar enthalpy of formation of CdMoO4(s) has been calculated to be ?fH°(298.15 K) = -(1034.3 ± 5.7) kJ mol-1. This value of enthalpy of formation of CdMoO4(s) agrees well with the estimated enthalpy of formation of this compound. There is no other report on the thermodynamic property measurements on this compound.

Ali (Basu), M.; Bharadwaj, S. R.; Das, D.

2005-01-01

277

Standard molar enthalpy of formation of monothiodibenzoylmethane by rotating-bomb calorimetry  

Microsoft Academic Search

The standard (p?=0.1 MPa) molar enthalpies of formation of crystalline thianthrene and monothiodibenzoylmethane, HDBMS, at T=298.15 K were measured by rotating-bomb calorimetry and the standard molar enthalpies of sublimation at T=298.15 K of dibenzoylmethane (HDBMO) and monothiodibenzoylmethane (HDBMS) were measured by microcalorimetry.?cUm?(cr)\\/(kJ·mol?1)?fHm?(cr)\\/(kJ·mol?1)?crgHm?\\/(kJ·mol?1)Thianthrene– 7239.1±2.5182.1±3.1HDBMS– 8203.7±2.0– 6.0±2.8125.5±4.9HDBMO113.3±4.8From the present results it could be shown that, in these molecules, the intramolecular hydrogen bond

Manuel A. V. Ribeiro da Silva; Lu??s M. N. B. F. Santos

2004-01-01

278

Age estimation using third molar teeth: A study on southern Saudi population  

PubMed Central

Objective: To estimate the age of an individual between 13 and 23 years, using Demirjian method in Saudi male patients in the southern region of the Kingdom of Saudi Arabia. Materials and Methods: A total of 360 male patient's digital panoramic radiographs were used to evaluate the morphology of mandibular 3rd molar teeth roots according to the Demirjian method. Using descriptive statistical method, age was calculated. Results: Result showed a strong relation of age with stages of root development of 3rd molar teeth. The standard deviation of mean of root development stages is 1.47 years of age. Conclusion: This study suggests that age can be predicted with a statistical significant result for ages between 13 and 23. Further studies with large population are needed for better statistical results and for female age assessment.

Ajmal, Muhammed; Assiri, Khalil Ibrahim; Al-Ameer, Khyrat Yahya; Assiri, Ahmad Mohammed; Luqman, Master

2012-01-01

279

Efficacy of composites filled with nanoparticles in permanent molars: Six-month results.  

PubMed

This study sought to evaluate the clinical performance of composites filled with nanoparticles six months after placement in the occlusal surface of molars with Class I cavities. This study involved 41 patients, each of whom had three molars affected by primary caries or the need to replace restorations. All restorations were performed in accordance with the manufacturer's recommendations and evaluated in accordance with USPHS modified criteria. Based on the results of the present study, composites reinforced with nanoparticles can be used in posterior teeth, although their performance was not superior to that of the microhybrid composite. Long-term re-evaluations are necessary for a more detailed analysis of these composites. PMID:20829151

Andrade, Ana Karina M; Duarte, Rosangela M; Silva, Fabia Danielle S C M; Batista, Andre Ulisses D; Lima, Kenio C; Pontual, Maria Luiza A; Montes, Marcos Ajr

280

Use of cone-beam computed tomography to evaluate root and canal morphology of mandibular first and second molars in Turkish individuals.  

PubMed

Objective: The aim of this study was to investigate the root and canal morphology of mandibular first and second molars in a Turkish population by using cone beam computed tomography (CBCT). Study design: CBCT images of mandibular first (n = 823) and second molar (n = 925) teeth from 605 Turkish patients were analyzed. The root canal configurations were classified according to the method of Vertucci. Results: The majority of mandibular molars (95.8% of first molars, 85.4% of second molars) had two separate roots; however, three roots were identified in 2.06% of first molars and 3.45% of second molars. C-shaped canals occurred 0.85% of first molars and 4.1% of second molars. Three canals were found in 79.9% of first molars and 72.8% of second molars. Most distal roots had a simple type I configuration, whereas mesial roots had more complex canal systems, with more than one canal. The most common root morphology of first and second molars is the two rooted morphology with three canals. Both the mesial and distal roots showed wide variations in canal anatomy with type IV and type I canal configuration predominating in the mesial and distal roots, respectively. Conclusion: Vertucci type I and IV canal configurations were the most prevalent in the distal and mesial roots, respectively, of both the mandibular first and second permanent molar teeth. PMID:23524421

Demirbuga, S; Sekerci, A-E; Dinçer, A-N; Cayabatmaz, M; Zorba, Y-O

2013-07-01

281

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\\u000a of placental villi. Using microsatellite markers amplified by the polymerase chain reaction, we have performed a genetic study\\u000a on eight independent molar tissues occurring in two sisters. Karyotype and genotype data demonstrate a diploid and biparental\\u000a constitution in seven of the analyzed

M. N. Helwani; M. Seoud; L. Zahed; G. Zaatari; A. Khalil; R. Slim

1999-01-01

282

Association between Enamel Hypoplasia and Dental Caries in Primary Second Molars: A Cohort Study  

PubMed Central

The purpose of this study was to assess the longitudinal relationships between enamel hypoplasia and caries experience of primary second molars. The study sample was 491 subjects who received dental examinations at both age 5 and 9 by the calibrated examiners. Four primary second molars (n = 1,892) were scored for the presence of enamel hypoplasia for each participant. Caries presence and number of decayed and filled surfaces (dfs) were determined at age 5 and 9. The relationships between enamel hypoplasia and caries experience were assessed. Among primary second molars, 3.9% of children and 1.7% of primary second molars had enamel hypoplasia. At age 5, 36.8% of children with hypoplasia had caries, while 16.9% of children without enamel hypoplasia had caries. At age 9, the corresponding numbers were 52.6% for children with hypoplasia and 34.5% for children without hypoplasia, respectively. At the tooth level, for age 5, 28.1% of teeth with hypoplasia had caries (mean dfs = 0.40), and 7.6% of teeth without hypoplasia had caries (mean dfs = 0.11). At age 9, the corresponding numbers were 41.9% (mean dfs = 0.76) for teeth with hypoplasia and 18.3% (mean dfs = 0.34) for teeth without hypoplasia. In multivariable logistic regression analyses, teeth of subjects with enamel hypoplasia had a significantly higher risk for caries at age 5 and 9 after controlling for other risk factors. Enamel hypoplasia appears to be a significant risk factor for caries and should be considered in caries risk assessment.

Hong, L.; Levy, S.M.; Warren, J.J.; Broffitt, B.

2009-01-01

283

Light-cured Calcium Hydroxide vs Formocresol in Human Primary Molar Pulpotomies: A Randomized Controlled Trial  

Microsoft Academic Search

Purpose: The purpose of this prospective study was to compare light-cured calcium hydroxide (Ca(OH)2) with diluted formocresol (FC) for its 2) with diluted formocresol (FC) for its 2 success as a primary molar pulpotomy medicament. Methods: Selection criteria included at least 2 matching, asymptomatic, contralateral primary mo- lars requiring vital pulpotomies. Matched teeth in each patient were randomized to receive

Derek Zurn; N. Sue Seale

284

In Vivo Debridement Efficacy of Ultrasonic Irrigation Following Hand-Rotary Instrumentation in Human Mandibular Molars  

Microsoft Academic Search

This study histologically compared the in vivo debridement efficacy of hand\\/rotary canal preparation versus a hand\\/rotary\\/ultrasound technique in mesial root canals of vital mandibular molars. Group 1 consisted of 16 teeth prepared with a hand\\/rotary technique whereas group 2 consisted of 15 teeth prepared in similar fashion but followed by 1 min of ultrasonic irrigation, per canal, utilizing an ultrasonic

Rubin Gutarts; John Nusstein; Al Reader; Mike Beck

2005-01-01

285

Rat wct mutation induces a hypomineralization form of amelogenesis imperfecta and cyst formation in molar teeth  

Microsoft Academic Search

Our previous findings have demonstrated that the rat autosomal-recessive mutation, whitish chalk-like teeth (wct), induces enamel defects resembling those of human amelogenesis imperfecta (AI) in continuously growing incisor teeth. The\\u000a present study clarifies the effect of the wct mutation on the morphogenesis and calcification of rat molar teeth. Formalin-fixed maxillae obtained from animals aged 4-30 days\\u000a were examined by electron probe

Masaru Osawa; Shin-ichi Kenmotsu; Taku Masuyama; Kazuyuki Taniguchi; Takashi Uchida; Chikara Saito; Hayato Ohshima

2007-01-01

286

In Vivo Debridement Efficacy of Ultrasonic Irrigation Following Hand-Rotary Instrumentation in Human Mandibular Molars  

Microsoft Academic Search

This study histologically compared the in vivo debride- ment efficacy of hand\\/rotary canal preparation versus a hand\\/rotary\\/ultrasound technique in mesial root canals of vital mandibular molars. Group 1 consisted of 16 teeth prepared with a hand\\/rotary technique whereas group 2 consisted of 15 teeth prepared in similar fash- ion but followed by 1 min of ultrasonic irrigation, per canal, utilizing

Rubin Gutarts; John Nusstein; Mike Beck

2005-01-01

287

Hunter-Schreger band orientation in interproximal enamel of modern human molars with complex morphological traits  

Microsoft Academic Search

A recent paper concerning characteristic groove-shaped wear in interproximal attritional facets of Neandertal posterior teeth\\u000a correlated groove formation with deep enamel structural traits (Villa & Giacobini, 1995). Further studies were carried out\\u000a on modern human teeth in order to evaluate a possible correlation between deep enamel structure and some crown complex morphological\\u000a features.\\u000a \\u000a Seventy-five isolated molars from medieval and recent

G. Villa

1996-01-01

288

Immunohistochemical localization of calbindin D28k during root formation of rat molar teeth  

Microsoft Academic Search

The present study was undertaken to examine the localization of calbindin D28k (CB)-like immunoreactivity (-LI) during the root formation of the rat molar. In the adult rat, CB-LI was detected in some of the cells of the epithelial rest of Malassez at the bifurcational region and in certain cells between the root dentin and cementum at the apical region. These

T. Onishi; T. Ooshima; S. Sobue; M. J. Tabata; T. Maeda; K. Kurisu; S. Wakisaka

1999-01-01

289

Physiological distal drift in rat molars contributes to acellular cementum formation.  

PubMed

Occlusal forces may induce the physiological teeth migration in humans, but there is little direct evidence. Rat molars are known to migrate distally during aging, possibly caused by occlusal forces. The purpose of this study was to determine if a reduction in occlusion would decrease teeth migration and affect associated periodontal structures such as cementum. To reduce occlusal forces, the right upper first molar (M1) in juvenile rats was extracted. The transition of the position of upper second molar (M2) and formation of M2 cementum was followed during aging. From the cephalometric analyses, upper M2 was located more anterior compared with the original position with aging after M1 extraction. Associated with this "slowing-down" of the physiological drift, cementum thickness on distal surface, but not on mesial surface, of M2 root was significantly increased. The accumulation of alizarin red as vital stain indicative of calcification, was observed in the distal cementum of M2 root only on the side of M1 extraction. Extraction of M1 that results in less functional loading, distinctly attenuates the physiological drift only in the upper dentition. The decreased physiological drift appears to activate acellular cementum formation only on distal surface of M2 root, perhaps due to reduced mechanical stress associated with the attenuated distal drift. In conclusion, the physiological distal drift in rat molars appears to be largely driven by the occlusal force and also affects the formation of acellular cementum. These findings provide additional direct evidence for an important role of occlusal forces in tooth migration. PMID:23775928

Tsuchiya, Shinobu; Tsuchiya, Masahiro; Nishioka, Takashi; Suzuki, Osamu; Sasano, Yasuyuki; Igarashi, Kaoru

2013-06-17

290

Expression of growth hormone receptor by immunocytochemistry in rat molar root formation and alveolar bone remodeling  

Microsoft Academic Search

Growth hormone (GH) may regulate tooth formation and bone remodeling associated with tooth eruption. This study reports the distribution of growth hormone receptor\\/binding protein in developing rat molars and adjacent alveolar bone by immunocytochemistry using well-characterized anti-growth hormone receptor monoclonal antibodies. These tissues represent an excellent model for studying the ontogenic changes that occur in odontogenic and osteogenic cells, as

Chayvis Z. Zhang; W. G. Young; H. Li; A. M. Clayden; J. Garcia-Aragon; M. J. Waters

1992-01-01

291

Risk Indicators of Postoperative Complications following Surgical Extraction of Lower Third Molars  

Microsoft Academic Search

Objective: The aim of this prospective clinical trial was to evaluate the incidence of postoperative complications following surgical extraction of lower third molars (L8) and the risk factors and clinical variables associated with these complications. Subjects and Methods: Three-hundred and twenty-seven consecutive patients (128 men and 199 women, mean age = 23.1 ± 3.9 years, range: 18–40) were recruited to

Ziad Malkawi; Mahmoud K. Al-Omiri; Ameen Khraisat

2011-01-01

292

Sealing Caries in Primary Molars: Randomized Control Trial, 5-year Results  

Microsoft Academic Search

The Hall Technique (HT) is a method for managing carious primary molars. Decay is sealed under pre-formed metal crowns without any caries removal, tooth preparation, or local anesthesia. The aim of this study was to compare HT clinical\\/radiographic failure rates with General Dental Practitioners’ (GDPs) standard (control) restorations. We conducted a split-mouth, randomized control trial (132 children, aged 3-10 yrs,

N. P. T. Innes; D. J. P. Evans; D. R. Stirrups

2011-01-01

293

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.

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

2012-01-01

294

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

295

Expression of galanin receptor-1 (GALR1) in the rat trigeminal ganglia and molar teeth  

Microsoft Academic Search

The expression of galanin receptor-1 (GALR1) was investigated in the rat trigeminal ganglion by using immunocytochemistry and in situ hybridization. In addition, the regional distribution of GALR1-immunoreactive pulpal nerves and their ultrastructure were examined in the molar teeth. In the trigeminal ganglion, the immunoreactivity for GALR1 was recognizable in about 30% of the total number of neurons. Most of the

Hironobu Suzuki; Toshihiko Iwanaga; Hiromasa Yoshie; Jun Li; Kaoru Yamabe; Noboru Yanaihara; Ülo Langel; Takeyasu Maeda

2002-01-01

296

Primary and Secondary Induction of Apoptosis in Odontoblasts after Cavity Preparation of Rat Molars  

Microsoft Academic Search

The death regulation of damaged pulp cells after cavity preparation is not well-known. In this study, we examined whether apoptosis is associated with the death regulation of damaged pulp cells. In normal rat molars, terminal deoxynucleotidyl transferase-mediated labeling (TUNEL)-positive cells were not observed. Just after surgery, odontoblasts under cavities were TUNEL-positive, and these signals disappeared in six hours. One day

C. Kitamura; K. Kimura; T. Nakayama; K. Toyoshima; M. Terashita

2001-01-01

297

Polymer Reference Materials: Round-Robin Tests for the Determination of Molar Masses  

Microsoft Academic Search

This article reports round-robin tests dealing with static light scattering (LS), size exclusion chromatography (SEC), and viscometry measurements of 10 reference materials of various polymer classes: poly(styrene)s (PS), poly(methyl methacrylate)s (PMMA), poly(ethylene oxide)s (PEO), and poly(lactide)s (PLA).In the certificates, molar masses and intrinsic viscosities as well as their uncertainties are specified. Additional values from nuclear magnetic resonance (NMR), infrared spectroscopy

U. Just; S. Weidner; P. Kilz; T. Hofe

2005-01-01

298

Fracture Resistance of Non-Metallic Molar Crowns Manufactured with CEREC 3D  

Microsoft Academic Search

Objectives. To compare fracture strength and fatigue resistance of ceramic (ProCAD, Ivoclar-Vivadent) (C) and resin composite (Paradigm MZ100, 3M\\/ ESPE) (R) crowns made with CEREC-3D. Methods. A prepared ivorine molar tooth was duplicated to produce 40 identical prepared specimens made of epoxy resin (Viade). Twenty (C) crowns and 20 (R) were cemented to their dies using resin cement. Ten of

Dalia A. Madani

2010-01-01

299

Microshear Bond Strength of Resin Composite to Teeth Affected by Molar Hypomineralization Using 2 Adhesive Systems  

Microsoft Academic Search

Purpose: When restoring hypomineralized first permanent molars, placement of cavo- surface margins can be difficult to ascertain due to uncertainty of the bonding capability of the tooth surface. The purpose of this study was to investigate the adhesion of resin composite bonded to control and hypomineralized enamel with an all-etch single-bottle adhesive or self-etching primer adhesive. Methods: Specimens of control

Vanessa William; Michael F. Burrow; Joseph E. A. Palamara; Louise B. Messer

2006-01-01

300

Mandibular second molar with C-shaped canal morphology and five canals: report of a case.  

PubMed

This article reviews a case involving endodontic treatment of a mandibular second molar with C-shaped canal morphology and five separate canals. The C-shaped canal variation of morphology is unusual and can lead to difficulties during treatment. Preoperative radiographs are limited in their ability to detect this entity; for a favorable treatment outcome, knowledge of the C-shaped canal's existence and morphology is essential. PMID:15206259

Benenati, Fred W

301

Molar and Canine Occlusal Changes in Study Casts before and after Treatment with Cervical Headgears  

Microsoft Academic Search

Aim:  We carried out a retrospective study on 246 pairs of casts to compare the extent of changes in occlusal relationship and overjet reduction induced by cervical headgears.Material amd Methods:  Molar-canine occlusal relationships and overjet were determined from study casts made immediately before headgear treatment. Those findings were then compared to another cast made immediately after headgear monotherapy and before multiband-appliance administration.

Arnim Godt; Matthias Kalwitzki; Gernot Göz

2006-01-01

302

The use of intraosseous screw for upper molar distalization: a case report.  

PubMed

The use of implants has made a major change in orthodontic treatment mechanics. They have replaced conventional unaesthetic and compliance dependent extraoral appliances with well accepted intraoral mechanics. Implants can be used in molar and canine distalization, intrusion and in extraoral force applications. In the present case report, treatment of a case using an intermaxillary fixation screw (IMF) will be presented. The treatment results will be evaluated using pretreatment, post distalization and post treatment cephalometric radiographs and dental casts. PMID:19212521

Polat-Ozsoy, Omür

2008-04-01

303

The Use of Intraosseous Screw for Upper Molar Distalization: A Case Report  

PubMed Central

The use of implants has made a major change in orthodontic treatment mechanics. They have replaced conventional unaesthetic and compliance dependent extraoral appliances with well accepted intraoral mechanics. Implants can be used in molar and canine distalization, intrusion and in extraoral force applications. In the present case report, treatment of a case using an intermaxillary fixation screw (IMF) will be presented. The treatment results will be evaluated using pretreatment, post distalization and post treatment cephalometric radiographs and dental casts.

Polat-Ozsoy, Omur

2008-01-01

304

Neonatal hamster molar tooth development: Extraction and characterization of amelogenins, enamelins, and soluble dentin proteins  

Microsoft Academic Search

Summary  Amelogenins, enamelins, and soluble dentin proteins were sequentially separated under dissociative conditions from morphologically\\u000a characterized molar tooth germs of 4-, 6-, and 7-day-old hamsters. Polyacrylamide gel electrophoretic, gel filtration chromatographic,\\u000a and amino acid compositional data of neonatal hamster amelogenin extracts were in general agreement with those obtained from\\u000a fetal bovine enamel under similar extraction conditions. As development progressed (e.g., 4

D. M. Lyaruu; A. Belcourt; A. G. Fincham; J. D. Termine

1982-01-01

305

Determination of the molar extinction coefficient for the ferric reducing\\/antioxidant power assay  

Microsoft Academic Search

The FRAP reagent contains 2,4,6-tris(2-pyridyl)-s-triazine, which forms a blue–violet complex ion in the presence of ferrous ions. Although the FRAP (ferric reducing\\/antioxidant power) assay is popular and has been in use for many years, the correct molar extinction coefficient of this complex ion under FRAP assay conditions has never been published, casting doubt on the validity of previous calibrations. A

William A. Hayes; Daniel S. Mills; Rachel F. Neville; Jenna Kiddie; Lisa M. Collins

2011-01-01

306

Evaluation of a one-appointment formocresol pulpectomy technique for primary molars  

Microsoft Academic Search

The purpose of this study was to evaluate the relative amount of root resorption in nonvital primary teeth after treatment with a 1-appointment formocresol pulpectomy. Thirty-seven children ranging in age from 2 years, 10 months to 8 years, 10 months received 41 pulpectomies in nonvital primary molars. At an initial follow-up examination, 6-36 months posttreatment (mean = 21 months), 80.5%

Jerome S. Casper

1985-01-01

307

Incidence of deep fascial space infection after surgical removal of the mandibular third molars  

Microsoft Academic Search

Nine hundred and ninety-three patients who underwent surgical removal of the mandibular third molars with oral antibiotic\\u000a prophylaxis were examined to determine the incidence of postoperative deep fascial space infection and its background factors.\\u000a Postoperative deep fascial space infection was observed in 8 of the patients (0.8%; 4 males and 4 females), and submandibular\\u000a spaces were involved in all infected

Takashi Yoshii; Yoshihiko Hamamoto; Shigetada Muraoka; Atsushi Kohjitani; Osamu Teranobu; Shungo Furudoi; Takahide Komori

2001-01-01

308

Strategies used to inhibit postoperative swelling following removal of impacted lower third molar  

PubMed Central

Postoperative swelling following different surgical strategies is an area of great interest. The main part of literature on the topic deals with swelling after extraction of low impacted third molar. In this review, we have analyzed publications of the last 20 years with a pubmed search using the following key words: impacted third molar, swelling third molar, wisdom tooth, edema jaw, corticosteroids and extraction third molar, antibiotic prophylaxis and tooth extraction. Attention has often been focused on corticosteroid therapy administered by diverse routes (orally, IV, IM, topically) and at different time schedules (before or after surgery or both). This investigation revealed how the use of different molecules and dosages makes the obtained results hardly comparable. Similar conclusions can be drawn from studies aimed at evaluating the efficacy of antibiotic therapy administered either before or after surgery. A complete review has also to take into account different surgical strategies used including various flaps, no traumatic osteothomy, and primary or secondary closure. The use of pharmacological therapy and application of an ice pack is critical in the postoperative period and has always provided positive results. However, even if it is difficult to come to definite conclusions, due to the variability of the design of studies analyzed, the postoperative discomfort identified with edema, pain and trismus following wisdom tooth removal is influenced by various factors such as the difficulty of the surgical procedure involved, age and gender of the patient, and experience of the surgeon. The pharmacological therapy when performed with corticosteroids seems to improve control of the postoperative swelling related with this kind of surgeries.

Sortino, Francesco; Cicciu, Marco

2011-01-01

309

Distal movement of premolars to provide posterior abutments for missing molars  

Microsoft Academic Search

In 24 patients with missing molar teeth in the upper and\\/or in the lower jaw, 32 premolars were distalized. The mean orthodontic distalizing distance was 9.4 mm (SD 2.6). After distalization all these teeth served as posterior abutments for fixed restorations. The investigation period ranged between 2.5 to 14.1 years, average 9.6 years (SD 3.2). The clinical examination criteria were

Peter R. Diedrich; Robert A. W. Fuhrmann; Heinrich Wehrbein; Heinz Erpenstein

1996-01-01

310

Summary of: The failure rate of NHS funded molar endodontic treatment delivered in general dental practice  

Microsoft Academic Search

Objective To describe the quality and record the outcomes of root canal therapy on mandibular, first permanent molar teeth provided by GDPs working according to NHS contracts.Design Descriptive, retrospective cohort study.Setting Twelve general dental practices in Salford, North West England.Subjects and method All patients aged 20-60 years attending the practices who had received a NHS-funded root filling in a mandibular

P. A. Brunton

2008-01-01

311

The failure rate of NHS funded molar endodontic treatment delivered in general dental practice  

Microsoft Academic Search

Objective To describe the quality and record the outcomes of root canal therapy on mandibular, first permanent molar teeth provided by GDPs working according to NHS contracts.Design Descriptive, retrospective cohort study.Setting Twelve general dental practices in Salford, North West England.Subjects and method All patients aged 20-60 years attending the practices who had received a NHS-funded root filling in a mandibular

K. Milsom; A. Qualtrough; F. Blinkhorn; V. R. Aggarwal; M. Tickle

2008-01-01

312

Radicular cyst associated with a primary first molar: A case report  

PubMed Central

Radicular cysts arising from deciduous teeth are rare. This report presents a case of radicular cyst associated with a primary molar following pulp therapy and discusses the relationship between pulp therapy and the rapid growth of the cyst. The treatment consisted of enucleation of the cyst sac and extraction of the involved primary teeth and 20 months follow up of the patient. Early diagnosis of the lesion would have lead to a less aggressive treatment plan.

Toomarian, L.; Moshref, M.; Mirkarimi, M.; Lotfi, A.; Beheshti, M.

2011-01-01

313

Rinsing with chlorhexidine may reduce incidence of dry socket after third molar surgery  

Microsoft Academic Search

Data sourcesMedline and the Science Citation Index were used and searches were made by hand for studies published in any language.Study selectionStudies included were human clinical trials evaluating the effect of a chlorhexidine (CHX) rinse on the incidence of alveolar osteitis (AO), following extraction of mandibular third molars, if they randomly assigned individuals to control and CHX rinse groups that

Jonathan Shepherd

2005-01-01

314

Odontoblast response to cavity preparation with Er:YAG laser in rat molars: an immunohistochemical study.  

PubMed

This study aimed to examine the dynamics of odontoblast-lineage cells following cavity preparation with erbium:yttrium-aluminum-garnet (Er:YAG) laser in rat molars. Cavity preparation was made with Er:YAG laser in the mesial surface of the maxillary left first molar of 8-week-old Wistar rats. Contralateral first molar served as unirradiated control. Immediately, 6 and 12 h and 1, 2, 3, 5 and 7 days after the lasing (n = 5, each), specimens were collected and processed for immunohistochemistry for heat-shock protein (HSP)-25 and nestin as markers for odontoblast-lineage cells. Cell proliferation assay using bromodeoxyuridine (BrdU) labeling was also performed. Unirradiated teeth showed HSP-25- and nestin-immunoreactivity in odontoblasts. At 6-12 h after irradiation, the odontoblastic layer was disorganized and some of odontoblasts lost the immunoreactivity to HSP-25 and nestin. At 1-2 days, however, HSP-25- and nestin-immunoreactivities in the odontoblast layer showed a noticeable recovery, resulting in the rearrangement of odontoblast-like cells intensely immunoreactive to HSP-25 and nestin at 3-7 days. BrdU-positive cells showed a significant increase at 2 days (P < 0.05 vs. immediate previous time point; one-way analysis of variance and Scheffé post hoc test), peaked at 3 days and then decreased significantly (P < 0.05). It was concluded that under the present experimental condition in rat molars, cavity preparation with Er:YAG laser induced mild and reversible damage to odontoblasts. The reparative process was characterized by the rearrangement of HSP-25- and nestin-immunoreactive odontoblast-like cells, which took place subsequent to the odontoblastic layer disorganization with partial loss of these immunoreactivities. PMID:22736273

Shigetani, Yoshimi; Suzuki, Hironobu; Ohshima, Hayato; Yoshiba, Kunihiko; Yoshiba, Nagako; Okiji, Takashi

2012-06-27

315

Measuring the molar mass of silicon for a better Avogadro constant: increased certainty  

Microsoft Academic Search

Summary form only given. At 3·10-5 combined uncertainty the abundance ratio measurements of Si isotopes in natural Si must still be improved in order for the uncertainty on the molar mass to become smaller than 1·10-7. One of the problems are the isotopic effects which result from adsorption\\/desorption processes of SiF4 in the ion source of the mass spectrometer. In

P. De Bievre; R. Gonfiantini; S. Valkiers; P. D. P Taylor

1996-01-01

316

Dietary molar ratios of phytate: Zinc and millimolar ratios of phytate × calcium: Zinc in South Koreans  

Microsoft Academic Search

The zinc nutritional status in south Koreans was established by evaluation of zinc, calcium and phytate intakes, the molar\\u000a ratio of phytate: zinc, and the millimolar ratio of phytate × calcium: zinc. The intakes of iron and magnesium were also estimated.\\u000a Sampling was designed so that it was representative of the national population. Two-day food records were used for the

In-Sook Kwun; Chong-Suk Kwon

2000-01-01

317

An elevation of the molar growth yield of Zymomonas mobilis during aerobic exponential growth  

Microsoft Academic Search

Elevated values of molar growth yield (Yx\\/s = 14–26 g mol–1) were obtained during exponential growth (? > 0.4 h–1) of Zymomonas mobilis ATCC 29191 by using reduced concentrations of glucose (6.25–100 mM) and increased oxygen supply (E\\u000a h > 300 mV) in the growth medium, as compared to the Yx\\/s of anaerobic exponential growth (8–10 g mol–1). Aerobically grown

Ramona Krú?e

1997-01-01

318

Nonsyndromic Bilateral Multiple Impacted Supernumerary Mandibular Third Molars: A Rare and Unusual Case Report  

PubMed Central

A supernumerary tooth is that which is present additionally to the normal series and can be found in any region of the dental arch. An impacted tooth is defined as the one which is embedded in the alveolus, so that its eruption is prevented, or the tooth is locked in position by bone or the adjacent teeth. The occurrence of multiple supernumerary teeth in only one patient in the absence of an associated systemic condition or syndrome is considered as a rare phenomenon. The occurrence of supernumerary teeth in the lower molar region is rare. A prevalence of less than 2% of cases occurring in this region has been estimated. Their occurrence presents a clinical problem for orthodontists and oral surgeons. The cause, frequency, complications, and surgical operation of impacted teeth are always interesting subjects for study and research. An impacted tooth can result in caries, pulp disease, periapical and periodontal disease, temporomandibular joint disorder, infection of the fascial space, root resorption of the adjacent tooth, and even oral and maxillofacial tumours. The management of impacted wisdom teeth has changed over the past 20 years from removal of nonsymptomatic third molars to simple observation. The aim of this paper is to present a rare case of bilateral multiple impacted supernumerary mandibular third molars.

Reddy, G. Siva Prasad; Reddy, G. V.; Krishna, I. Venkata; Regonda, Shravan Kumar

2013-01-01

319

Molar absorptivity and color characteristics of acylated and non-acylated pelargonidin-based anthocyanins.  

PubMed

The effects of glycosylation and acylation on the spectral characteristics, molar absorptivity, and color attributes of purified acylated and non-acylated pelargonidin derivatives were compared. Pigments were obtained from strawberries, radishes, red-fleshed potatoes, and partially hydrolyzed radish pigments. Individual pigments were isolated by using semipreparative HPLC. Spectral and color (CIELch) attributes of purified pigments were measured. Molar absorptivity ranged from 15 600 to 39 590 for pelargonidin-3-glucoside (pg-3-glu) and pg-3-rutinoside-5-glucoside acylated with p-coumaric acid, respectively. The presence of cinnamic acid acylation had a considerable impact on spectral and color characteristics, causing a bathochromic shift of lambda(max). Sugar substitution also played an important role, with a hypsochromic shift caused by the presence of glycosylation. Pg-3, 5-diglu and pg-3,5-triglu possessed a higher hue angle (>40 degrees ) than the other pg derivatives at pH 1.0, corresponding to the yellow-orange region of the color solid. Acylation with malonic acid did not affect lambda(max) and showed little effect on color characteristics. The solvent system had an effect not only on the molar absorptivity, but also on the visual color characteristic of the pigments. PMID:10552862

Giusti, M M; Rodríguez-Saona, L E; Wrolstad, R E

1999-11-01

320

Permanent molar pulpotomy with a new endodontic cement: A case series  

PubMed Central

The aim of this case series was to determine the clinical and radiographic success rate of pulpotomy, with new endodontic cement (NEC), in human mature permanent molar teeth. Twelve molars with established irreversible pulpitis were selected from patients 14 – 62 years old. The selection criteria included carious pulp exposure with a positive history of lingering pain. After isolation, caries removal, and pulp exposure, pulpotomy with NEC was performed and a permanent restoration was immediately placed. At the first recall (+1 day) no patients reported postoperative pain. One wisdom tooth had been extracted after two months because of failure in coronal restoration. Eleven patients were available for the second recall, with a mean time of 15.8 months. Clinical and radiographic examination revealed that all teeth were functional and free of signs and symptoms. Histological examination of the extracted teeth revealed complete dentin bridge formation and a normal pulp. Although the results favored the use of NEC, more studies with larger samples and a longer recall period were suggested, to justify the use of this novel material for treatment of irreversible pulpitis in human permanent molar teeth.

Asgary, Saeed; Ehsani, Sara

2009-01-01

321

C-shaped canal system in mandibular second molars: Part II--Radiographic features.  

PubMed

The purpose of this study was to investigate the relation between the radiographic features of C-shaped mandibular second molars and the cross-sectional shapes of their root canal system. Fifty-eight extracted mandibular second molars with fused roots were collected from a native Chinese population. The teeth were scanned at 0.5-mm interval thickness by micro-computed tomography (microCT) and observed at 11 levels. The 54 teeth that possessed a C-shaped canal system were further examined. Their radiographic appearances were classified into three types according to discernible radiographic features. The results were subject to the Kruskal-Wallis statistical test. In these 54 molars, 16 teeth (29.63%) showed a type I radiographic image, 22 (40.74%) type II, and 16 (29.63%) type III. In the type I category, the C1 and C4 canal configurations were mostly found in the apical area. Categories C2 and C3 were the main configurations in the middle and apical areas in type II and III. The type III had more C2 canals in middle area than type II. These results suggested that it was possible to predict the presence and the configuration of C-shaped canal system by the radiographic appearance. PMID:15564875

Fan, Bing; Cheung, Gary S P; Fan, Mingwen; Gutmann, James L; Fan, Wei

2004-12-01

322

The Long-Term Effects of Mandibular Distraction Osteogenesis on Developing Deciduous Molar Teeth  

PubMed Central

Background. Many studies have demonstrated the effectiveness of mandibular distraction osteogenesis (MDO) in alleviating the micrognathia-associated upper airway obstruction but very few studies have focused on long-term dental outcomes. Objective. To report the effect of MDO on developing deciduous molars in the distraction area. Methods. A retrospective chart review was performed to identify patients with Pierre Robin sequence who underwent MDO with documented long-term dental assessments. Results. Ten children (mean age at surgery 69.8 days; 6 boys and 4 girls) were included for analysis. All patients underwent bilateral MDO with an inverted L-shaped osteotomy to avoid injuring tooth buds. The dental developmental stage was primary dentition in all children. Overall, 3 patients developed minor dental problems involving 4 molar teeth (2 root malformations and 2 shape anomalies) but they did not require any interventions. Conclusion. Significant primary molar developmental complications were not seen in our patients. The use of internal distractor device with an inverted L-shaped osteotomy seems to be a safe surgical approach in regards to dental outcomes.

Hong, Paul; Graham, Elise; Belyea, James; Taylor, S. Mark; Kearns, Donald B.; Bezuhly, Michael

2012-01-01

323

Bone regeneration after surgical repositioning of impacted mandibular second molars: a case report.  

PubMed

A case is presented where the mesially impacted mandibular second molar teeth were surgically uprighted in an 11-year-old female patient. Bone regeneration is shown in the areas occupied by the impacted second molars with maturation of bone and cortication of the crest of the alveolar bone. The probing depths are also normal with no residual bony defects. This healing was achieved with no bone grafting procedure, emphasizing two important factors: to prevent/minimize any trauma to the tissues at the site of elevation and uprighting of the tooth (i.e. maintaining viable periodontal ligament cells and minimal cementum damage); and to obtain primary closure whilst allowing the tissue in the mesial defect to reorganize against the scaffold of bone. However, the procedure on the one side was complicated with necrosis and infection of the pulp space with external inflammatory root resorption. Endodontic therapy of this tooth proved to be successful with periradicular healing radiographically and re-establishment of the lamina dura. At the 3-year follow-up, the endodontically treated tooth showed no clinical and radiographic signs of pathology. The left second mandibular molar had no pulpal or periodontal postsurgical complications, which may be attributed to apparently more open apices allowing for pulp revascularization after manipulation at the time of surgery. This report illustrates unassisted wound healing that occurs in the area of uprighting with complete reconstitution of periodontal anatomy without additional regenerative procedures to augment bone. PMID:12656843

Shipper, Guy; Thomadakis, George

2003-04-01

324

Molecular representation of molar domain (volume), evolution equations, and linear constitutive relations for volume transport.  

PubMed

In the traditional theories of irreversible thermodynamics and fluid mechanics, the specific volume and molar volume have been interchangeably used for pure fluids, but in this work we show that they should be distinguished from each other and given distinctive statistical mechanical representations. In this paper, we present a general formula for the statistical mechanical representation of molecular domain (volume or space) by using the Voronoi volume and its mean value that may be regarded as molar domain (volume) and also the statistical mechanical representation of volume flux. By using their statistical mechanical formulas, the evolution equations of volume transport are derived from the generalized Boltzmann equation of fluids. Approximate solutions of the evolution equations of volume transport provides kinetic theory formulas for the molecular domain, the constitutive equations for molar domain (volume) and volume flux, and the dissipation of energy associated with volume transport. Together with the constitutive equation for the mean velocity of the fluid obtained in a previous paper, the evolution equations for volume transport not only shed a fresh light on, and insight into, irreversible phenomena in fluids but also can be applied to study fluid flow problems in a manner hitherto unavailable in fluid dynamics and irreversible thermodynamics. Their roles in the generalized hydrodynamics will be considered in the sequel. PMID:19044872

Eu, Byung Chan

2008-09-01

325

Effect of solution molarity on the characteristics of vanadium pentoxide thin film  

NASA Astrophysics Data System (ADS)

Vanadium pentoxide (V 2O 5) thin films have been prepared by spray pyrolysis technique. The influence of solution molarity on the characteristics of the V 2O 5 has been investigated. X-ray diffraction analysis (XRD) showed that, the films deposited at ?0.1 M were orthorhombic structure with a preferential orientation along <0 0 1> direction. Moreover, the crystallinity was improved by increasing solution molarity. The microstructure parameters have been evaluated by using a single order Voigt profile method. The optical band gaps, determined by using Tauc plot, have been found to be 2.50 ± 0.02 and 2.33 ± 0.02 eV for the direct and indirect allowed transition, respectively. Also the complex optical constants for the wavelength range 300-2500 nm are reported. At room temperature, the dark conductivity as a function of solution molarity showed the range of 5.74 × 10 -2 ± 0.03 to 3.36 × 10 -1 ± 0.02 ? -1 cm -1. While at high temperature, the behaviour of electrical conductivity dominated by grain boundaries. The values of activation energy and potential barrier height were 0.156 ± 0.011 and 0.263 ± 0.012 eV, respectively.

Akl, Alaa A.

2006-10-01

326

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

327

Brief communication: dental development and enamel thickness in the Lakonis Neanderthal molar.  

PubMed

Developmental and structural affinities between modern human and Neanderthal dental remains continue to be a subject of debate as well as their utility for informing assessments of life history and taxonomy. Excavation of the Middle Paleolithic cave site Lakonis in southern Greece has yielded a lower third molar (LKH 1). Here, we detail the crown development and enamel thickness of the distal cusps of the LKH 1 specimen, which has been classified as a Neanderthal based on the presence of an anterior fovea and mid-trigonid crest. Crown formation was determined using standard histological techniques, and enamel thickness was measured from a virtual plane of section. Developmental differences include thinner cuspal enamel and a lower periodicity than modern humans. Crown formation in the LKH 1 hypoconid is estimated to be 2.6-2.7 years, which is shorter than modern human times. The LKH 1 hypoconid also shows a more rapid overall crown extension rate than modern humans. Relative enamel thickness was approximately half that of a modern human sample mean; enamel on the distal cusps of modern human third molars is extremely thick in absolute and relative terms. These findings are consistent with recent studies that demonstrate differences in crown development, tissue proportions, and enamel thickness between Neanderthals and modern humans. Although overlap in some developmental variables may be found, the results of this and other studies suggest that Neanderthal molars formed in shorter periods of time than modern humans, due in part to thinner enamel and faster crown extension rates. PMID:18711737

Smith, T M; Harvati, K; Olejniczak, A J; Reid, D J; Hublin, J-J; Panagopoulou, E

2009-01-01

328

Acetaminophen, pesticide, and diethylhexyl phthalate metabolites, anandamide, and fatty acids in deciduous molars: potential biomarkers of perinatal exposure.  

PubMed

The developing fetus is particularly vulnerable to adverse effects from pharmaceutical and exogenous chemical exposure. Deciduous teeth primarily form over specific periods from the second trimester in utero through the months after birth. We hypothesized that organic chemicals or their metabolites circulating in the bloodstream may sorb into forming dental tissues and remain stored in the tooth thereafter. Our aims were to devise analytical and preparation methods for potentially toxic or beneficial organic chemicals or metabolites in deciduous teeth and to estimate their detection frequencies. The analgesic acetaminophen was stored at greater concentration in a child's second molar than a first molar, consistent with intake, suggesting that acetaminophen concentration in molars may be a biomarker of acetaminophen exposure during molar formation. Chemicals detected by liquid chromatography/tandem mass spectrometry in molars of 21 typically developing children include the endocannabinoid anandamide (86% of children), acetaminophen (43%), and specific metabolites mono-2-ethylhexyl phthalate (MEHP, of plasticizer di-2-ethylhexyl phthalate, 29%), 3,5,6-trichloro-2-pyridinol (TCPy, of organophosphate (OP) insecticide chlorpyrifos, 10%), and 2-isopropyl-6-methyl-4-pyrimidinol (IMPy, of OP insecticide diazinon, 10%). None of these chemicals has previously been detected in human teeth. Molars from the two oldest subjects contained the largest concentrations of MEHP, TCPy, and IMPy. Potentially protective fatty acids detected by gas chromatography/mass spectrometry after derivatization include docosahexaenoic (19%), arachidonic (100%), and linoleic (100%). Validation studies are necessary to verify that each detected chemical in molars provides a biomarker of perinatal exposure. PMID:22805989

Camann, David E; Schultz, Stephen T; Yau, Alice Y; Heilbrun, Lynne P; Zuniga, Michelle M; Palmer, Raymond F; Miller, Claudia S

2012-07-18

329

Do erupted third molars weaken the mandibular angle after trauma to the chin region? A 3D finite element study.  

PubMed

It has been suggested that third molars increase mandibular fragility because they do not contribute to its strength. For ethical reasons, a human study design that would permit the elucidation of this interference is not possible. This study evaluated the impact of the presence of erupted third molars on the mandibular angle of resistance when submitted to trauma. A three-dimensional (3D) mandibular model was obtained through finite element methodology using computed tomography (CT) with the geometry and mechanical properties to reproduce a normal mandibular structure. Human mandibles with no, one or two erupted third molars were evaluated. Whenever the third molar was present there was a greater concentration of tensions around the cervical part of its alveolus. Approximated Von Mises equivalent stress of the third molar region was 107.035 MPa in the mandible with teeth and 64.6948 MPa in the mandible without teeth. In the condylar region it was 151.65 MPa when the third molar was present and 184.496 MPa when it was absent. The digital models created proved that the mandibular angle becomes more fragile in the presence of third molars. When they are absent the energy concentrates on the lateral e posterior aspect of the condylar neck. PMID:23158028

Bezerra, T P; Silva Junior, F I; Scarparo, H C; Costa, F W G; Studart-Soares, E C

2012-11-15

330

Absorption of Nickel, Chromium, and Iron by the Root Surface of Primary Molars Covered with Stainless Steel Crowns  

PubMed Central

Objective. The purpose of this study was to analyze the absorption of metal ions released from stainless steel crowns by root surface of primary molars. Study Design. Laboratory research: The study included 34 primary molars, exfoliated or extracted during routine dental treatment. 17 molars were covered with stainless-steel crowns for more than two years and compared to 17 intact primary molars. Chemical content of the mesial or distal root surface, 1?mm apically to the crown or the cemento-enamel junction (CEJ), was analyzed. An energy dispersive X-ray spectrometer (EDS) was used for chemical analysis. Results. Higher amounts of nickel, chromium, and iron (5-6 times) were found in the cementum of molars covered with stainless-steel crowns compared to intact molars. The differences between groups were highly significant (P < .001). Significance. Stainless-steel crowns release nickel, chromium, and iron in oral environment, and the ions are absorbed by the primary molars roots. The additional burden of allergenic metals should be reduced if possible.

Keinan, David; Mass, Eliyahu; Zilberman, Uri

2010-01-01

331

Root canal configuration and the prevalence of C-shaped canals in mandibular second molars in an Iranian population.  

PubMed

A total of 139 extracted mandibular second molars were injected with India ink and demineralized. They were made clear and transparent with methyl salicylate, and the anatomy of their canals was studied. It was found that 86.3% of mandibular second molars had two roots, 9.3% had one root, and 4.3% had three roots. Ninety percent of the mesial roots of the mandibular second molars with two roots had two canals (predominantly with a type II or III configuration), and 77.5% of the distal roots of these teeth had one canal (predominantly with a type I configuration). Among the mandibular second molars, 7.2% had C-shaped canals and these configurations were seen mostly in single-rooted mandibular second molars. The results of this study indicate that mandibular second molar teeth have many variations in the number of roots and the morphology of their canals. Therefore it should not be assumed that all mandibular second molar teeth have two roots and three canals. PMID:18403877

Rahimi, Saeed; Shahi, Shahriar; Lotfi, Mehrdad; Zand, Vahid; Abdolrahimi, Majid; Es'haghi, Reza

2008-03-01

332

Why is RCM favoured over dimerisation? Predicting and estimating thermodynamic effective molarities by solution experiments and electronic structure calculations.  

PubMed

The thermodynamic effective molarities of a series of simple cycloalkenes, synthesised from ?,?-dienes by reaction with Grubbs' second generation precatalyst, have been evaluated. Effective molarities were measured from a series of small scale metathesis reactions and agreed well with empirical predictions derived from the number of rotors and the product ring strain. The use of electronic structure calculations (at the M06-L/6-311G** level of theory) was explored for predicting thermodynamic effective molarities in ring-closing metathesis. However, it was found that it was necessary to apply a correction to DFT-derived free energies to account for the entropic effects of solvation. PMID:21971759

Nelson, David J; Ashworth, Ian W; Hillier, Ian H; Kyne, Sara H; Pandian, Shanthi; Parkinson, John A; Percy, Jonathan M; Rinaudo, Giuseppe; Vincent, Mark A

2011-10-04

333

Diagnosis, classification, and frequency of C-shaped canals in mandibular second molars in the Lebanese population.  

PubMed

C-shaped canals are mostly found in mandibular second molars. Studies have shown that frequency ranges from 2.7 to 31%. This study was undertaken to provide further knowledge of the distribution of such canal anatomy, by determining the frequency of C-shaped canals in a sample representing the Lebanese population. Ninety-four mandibular second molars with scheduled endodontic treatment were examined over a 1-yr period. Of the 94 treated molars, 18 exhibited C-shaped canals that would represent 19.1% of the sample. The geographical position of Lebanon could represent an explanation for this phenomenon. PMID:10425954

Haddad, G Y; Nehme, W B; Ounsi, H F

1999-04-01

334

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.

Duarte, Bruno G.; Assis, Diogo; Ribeiro-Junior, Paulo; Goncales, Eduardo Sanches

2012-01-01

335

Spiral Computed Tomographic Evaluation and Endodontic Management of a Mandibular Second Molar with Four Roots. A Case Report and Literature Review  

PubMed Central

The vast majority of mandibular second molars have two roots with three root canals; however, variations in molar root canal anatomy are not uncommon. To the best of our knowledge, four rooted mandibular second molar with three mesial roots and one distal root has never been reported. Herein, we present the endodontic management of a four rooted mandibular second molar tooth, diagnosed with the assistance of spiral computed tomography (SCT) with a brief review of literature.

Purra, Aamir Rashid; Mushtaq, Mubashir; Robbani, Irfan; Farooq, Riyaz

2013-01-01

336

Thermodynamics for self-association of caffeine in water: apparent molar volumes and apparent molar heat capacities of aqueous caffeine at temperatures from 278.15 to 393.15 K and at the pressure 0.35 MPa  

Microsoft Academic Search

We have determined the apparent molar volumes V? and the apparent molar heat capacities Cp,? for aqueous solutions of caffeine at temperatures T from 278.15K to 393.15K, at the pressure 0.35MPa, and at molalities m from 0.01mol·kg?1 to 0.1mol·kg?1. We used a vibrating tube densimeter (DMA 512P, Anton PAAR, Austria) to determine the densities and volumetric properties, and a twin

M. L Origlia-Luster; B. A Patterson; E. M Woolley

2002-01-01

337

Simulated fatigue resistance of composite resin versus porcelain CAD\\/CAM overlay restorations on endodontically treated molars  

Microsoft Academic Search

Objective: To assess the influence of material selection (porcelain versus composite resin) for overlay-type restoration of endodontically treated molars and its effect on the in vitro fatigue resistance and failure mode. Method and Materials: A standardized tooth prepara- tion was applied to 30 extracted molars, including root canal treatment, 3-mm coverage of all cusps, a mesial box 1.5 mm below

Pascal Magne; Alena Knezevic

338

Root canal morphology of the mesiobuccal root of maxillary first molars: a micro-computed tomographic analysis  

Microsoft Academic Search

Somma F, Leoni D, Plotino G, Grande NM, Plasschaert A. Root canal morphology of the mesiobuccal root of maxillary first molars: a micro-computed tomographic analysis. International Endodontic Journal, 42, 165-174, 2009. Aim To investigate ex vivo, the root canal morphology of the MB root of maxillary first molar teeth by means of micro-computed tomography. Methodology Thirty extracted intact human maxillary

F. Somma; D. Leoni; G. Plotino; N. M. Grande; A. Plasschaert

2009-01-01

339

Incidence of symptoms in previously symptom-free impacted lower third molars assessed in general dental practice  

Microsoft Academic Search

Aim To determine the potential of a pathology-free impacted lower third molar to cause symptoms within a year and whether these symptoms can be linked to clinical characteristics, lifestyle or socio-demographic status.Design One-year prospective cohort study of patients registered in general dental practice in Scotland with at least one asymptomatic impacted lower third molar.Methods All general dental practices with panoramic

G. R. Ogden; N. B. Pitts; S. A. Ogston; D. A. Ruta; M. J. Fernandes

2009-01-01

340

Summary of: 'Incidence of symptoms in previously symptom-free impacted lower third molars assessed in general dental practice'  

Microsoft Academic Search

Aim To determine the potential of a pathology-free impacted lower third molar to cause symptoms within a year and whether these symptoms can be linked to clinical characteristics, lifestyle or socio-demographic status.Design One-year prospective cohort study of patients registered in general dental practice in Scotland with at least one asymptomatic impacted lower third molar.Methods All general dental practices with panoramic

G. R. Ogden; N. B. Pitts; S. A. Ogston; D. A. Ruta; M. J. Fernandes

2009-01-01

341

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

342

Influence of molar mass distribution and long-chain branching on strain hardening of low density polyethylene  

Microsoft Academic Search

Low-density polyethylenes (LDPE) were synthesized in a laboratory-scale autoclave under high pressure. These samples were\\u000a found to possess a high molar mass tail, resulting in a distinctly bimodal molar mass distribution and a lower concentration\\u000a of long-chain branching than typical of commercial LDPEs. Rheological experiments in elongation showed that these samples\\u000a exhibit a very pronounced strain hardening, which could be

Florian J. Stadler; Joachim Kaschta; Helmut Münstedt; Florian Becker; Michael Buback

2009-01-01

343

C-shaped Canal System in Mandibular Second Molars Part III: The Morphology of the Pulp Chamber Floor  

Microsoft Academic Search

The purpose of this study was to investigate the morphology of pulp chamber floors in mandibular second molars with a C-shaped canal system. Forty-four extracted mandibular second molars with C-shaped roots were collected from a native Chinese population. After the teeth were scanned by the micro-computed tomography (?CT), the pulp chamber floors were reconstructed three-dimensionally using three-dimensional software. The reconstructed

Yi Min; Bing Fan; Gary S. P. Cheung; James L. Gutmann; Mingwen Fan

2006-01-01

344

Implantation of an RFID-tag into human molars to reduce hard forensic identification labor. Part 2: Physical properties  

Microsoft Academic Search

Modifying and implanting existing RFID-tags into extracted human molars was described previously [P. Thevissen, G. Poelman, B. Puers, M. De Cooman, G. Willems, Implantation of RFID-tag into human molars to reduce hard forensic identification labor. Part 1. Working principle, Forensic Sci. Int. 156 (2006)]. Maximal vertical occlusal load during which the implanted RFID-tags remain active was evaluated in vitro. The

Patrick W. Thevissen; Guy Poelman; Michel De Cooman; Robert Puers; Guy Willems

2006-01-01

345

Comparison of antibacterial efficacy of intracanal medicaments in multiple visit pulpectomies in primary molars-an in vivo study.  

PubMed

Antibacterial efficacy of formocresol, 2% gluteraldehyde and iodine-potassium iodide was assessed by obtaining cultures at consecutive appointments in multiple visit pulpectomies in primary molars. Formocresol and 2% gluteraldehyde were more effective as intracanal medicaments and caused significant reduction in the counts of aerobic and anaerobic microorganisms, thereby supporting the need for placing intracanal medicaments with antibacterial properties, in multiple visit pulpectomies in primary molars. PMID:20215667

Lele, G S; Subba Reddy, V V

346

Partial Molar and Ultrasonic Properties of Benzoic and Phenyl Acetic Acids in Water and Water + Alcohol Mixtures  

Microsoft Academic Search

Partial molar volumes of Benzoic and Phenylacetic acids have been determined in water and water + alcohol (5 wt% each of methanol, ethanol and propanol) mixtures from density measurements in varying ranges of concentration at four different temperatures in the interval of 10° from 288.15 to 318.15 K. The density data have been used to obtain partial molar volumes, co-efficients

U. N. Dash; B. K. Mohanty

1999-01-01

347

Specific heats of solid natural neon at five molar volumes and of the separated neon isotopes at P =0  

Microsoft Academic Search

Direct measurements of the constant volume specific heatCvare reported for solid natural neon at several molar volumes (13.39–12.39 cm3\\/mole) at temperatures from 1 K to the melting line. All samples were solidified in a high-pressure bomb at the melting line (maximum conditions of 53 K and 2.5 kbar) and molar volumes for the melting line are given. The extrapolations of

R. Q. Fugate; C. A. Swenson

1973-01-01

348

Specific heats of solid natural neon at five molar volumes and of the separated neon isotopes at P=0  

Microsoft Academic Search

Direct measurements of the constant volume specific heat C v are reported for solid natural neon at several molar volumes (13.39 12.39 cm3\\/mole) at temperatures from 1 K to the melting line. All samples were solidified in a high-pressure bomb at the melting line (maximum conditions of 53 K and 2.5 kbar) and molar volumes for the melting line are

R. Q. Fugate; C. A. Swenson

1973-01-01

349

Ionic Molar Conductivities in Solutions of KCl, NaCl and LiCl in Glycerol at 25°C  

Microsoft Academic Search

Conductivities of solutions of KCl, NaCl and LiCl in glycerol at 25°C have been measured for concentrations in the range 0.0005 to 0.5 mol dm, and values of molar conductivity at infinite dilution obtained by extrapolation. Using previously measured transference numbers for KCl dissolved in glycerol, values of ionic molar conductivities at infinite dilution have been deducted for K, Na,

M. C. Blanco; D. C. Champeney; M. Kameche

1989-01-01

350

Third mandibular molar radiological development as an indicator of chronological age in a European population.  

PubMed

Assessing biological age in the youth nearby legal age has always represented a stimulating issue for the Italian forensic scientist as far as he deals with matter of imputability and legal or illegal immigration of uncertain age subjects. Since any method of evaluation should of course be accurate, not invasive, reproducible and, as possible, easily exploitable, radiological investigation of age dependent features is the most appropriate instrument to the purpose. Dental development is slower and delayed compared with skeletal bone one, occurring according to a known, regular pattern from whose evaluation a biological age can be assessed with a reasonably restricted span for a certain radiological image. This is the assumption which inspired since 1941 (Schour e Massler) so many anthropologists and forensic and clinic odontologist in investigating biological age by the study of radiological dental morphology. Demirjian and Goldstein [New systems for dental maturity based on seven and four teeth, Ann. Hum. Biol. 3 (1976) 411-421] obtained no differences between two groups of subjects whose age was extimated by the evaluation of 14 teeth in one case and 7 teeth in another, the last being greatly simpler. Afterwards, Thorson (1991), Mincer et al. [The A.B.F.O. study of third molar development and its use as estimator of chronological age, J. Forensic Sci. 38 (1993) 379], Solari and Abramovitc [The accuracy and precision of third molar development as an indicator of chronological age in Hispanic, J. Forensic Sci. (3) (2002) 531-535] and then Prieto Carrero [Evaluation of Chronological Age Based on Third Molar Development in the Spanish Population, Atti del XIX Congresso IALM, Milano, 2003], developed a method based on the evaluation of the radiological development of the alone third molar, according to Demirjian's schematic definitions of crown and root formation. Eight stages of development of the third molar are defined from the time of mineralization appearance of the cusp tips up to complete closing of the apexes. In order to achieve grater precision in discriminating stages F and G, Solari added two stages (F1 and G1), determining 10 stages of maturation of root and crown. Prieto tested the accuracy and precision of this method by the evaluation of about 1300 orthopantomographs of juveniles and young Spanish adults of known age, divided for gender. We analyzed a total of 400 orthopantograms of young Spanish dental patients to evaluate the chronology of the right mandibular third molar development and to assess its correlation with the biological age of the tested. Biological age is attributed with a maximum standard deviation of 2.47 from the mean in the eight stages outline. The greatest limit of the method seems to be the operator experience in determining the dental stage of development. We think that age data coming from such evaluation method should be clearly explained to the magistrate in their true statistical significance and limits. PMID:15639599

De Salvia, Alessandra; Calzetta, Corinne; Orrico, Marco; De Leo, Domenico

2004-12-01

351

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.

Asahara, Masakazu

2013-01-01

352

Efficiency of noncompliance simultaneous first and second upper molar distalization: a three-dimensional tooth movement analysis.  

PubMed

Objective of this prospective study was the three-dimensional (3D) analysis of tooth movements after the noncompliance simultaneous distalization of the first and second maxillary molars. Ten patients (five girls and five boys; mean age: 13.2 years) with bilateral Class II molar relationships were treated with a noncompliance, fixed intraoral appliance. Upper second molars had already erupted in all cases. Dental casts and lateral cephalometric radiographs were taken immediately before placement and after removal of the appliance. The casts were 3D digitized and superimposed on a predefined area in the palate. The resulting holograms, as well as the cephalometric radiographs, were digitized and analyzed by means of customized cephalometric software. The whole procedure was repeated after a two- to four-week interval to estimate the error of both methods. The cast assessment of 3D sagittal and vertical tooth movements was more reliable than the cephalometric record. The average maxillary first molar distal movement was 2.8 mm. Anchorage loss was expressed by a 1.9-mm proclination of the central incisors. A substantial variation among patients and among the right and left side in the same patient was observed. Noncompliance simultaneous distalization of the first and second maxillary molars can be an efficient treatment option for the correction of Class II molar relationship. However, anchorage loss and individual variation have to be seriously considered. Bilaterally symmetrical effectiveness should not be relied upon. PMID:16097221

Mavropoulos, Anestis; Karamouzos, Andreas; Kiliaridis, Stavros; Papadopoulos, Moschos A

2005-07-01

353

The presence of accessory cusps in chimpanzee lower molars is consistent with a patterning cascade model of development  

PubMed Central

Tooth crown morphology is of primary importance in fossil primate systematics and understanding the developmental basis of its variation facilitates phenotypic analyses of fossil teeth. Lower molars of species in the chimp/human clade (including fossil hominins) possess between four and seven cusps and this variability has been implicated in alpha taxonomy and phylogenetic systematics. What is known about the developmental basis of variation in cusp number – based primarily on experimental studies of rodent molars – suggests that cusps form under a morphodynamic, patterning cascade model involving the iterative formation of enamel knots. In this study we test whether variation in cusp 6 (C6) presence in common chimpanzee and bonobo lower molars (n = 55) is consistent with predictions derived from the patterning cascade model. Using microcomputed tomography we imaged the enamel-dentine junction of lower molars and used geometric morphometrics to examine shape variation in the molar crown correlated with variation in C6 presence (in particular the size and spacing of the dentine horns). Results indicate that C6 presence is consistent with predictions of a patterning cascade model, with larger molars exhibiting a higher frequency of C6 and with the location and size of later-forming cusps correlated with C6 variation. These results demonstrate that a patterning cascade model is appropriate for interpreting cusp variation in Pan and have implications for cusp nomenclature and the use of accessory cusp morphology in primate systematics.

Skinner, Matthew M; Gunz, Philipp

2010-01-01

354

First molar eruption, weaning, and life history in living wild chimpanzees.  

PubMed

Understanding dental development in chimpanzees, our closest living relatives, is of fundamental importance for reconstructing the evolution of human development. Most early hominin species are believed to show rapid ape-like patterns of development, implying that a prolonged modern human childhood evolved quite recently. However, chimpanzee developmental standards are uncertain because they have never been based on living wild individuals. Furthermore, although it is well established that first molar tooth emergence (movement into the mouth) is correlated with the scheduling of growth and reproduction across primates broadly, its precise relation to solid food consumption, nursing behavior, or maternal life history is unknown. To address these concerns we conducted a photographic study of subadult chimpanzees (Pan troglodytes schweinfurthii) in Kanyawara, Kibale National Park, Uganda. Five healthy infants emerged their lower first molars (M1s) by or before 3.3 y of age, nearly identical to captive chimpanzee mean ages (?3.2 y, n = 53). First molar emergence in these chimpanzees does not directly or consistently predict the introduction of solid foods, resumption of maternal estrous cycling, cessation of nursing, or maternal interbirth intervals. Kanyawara chimpanzees showed adult patterns of solid food consumption by the time M1 reached functional occlusion, spent a greater amount of time on the nipple while M1 was erupting than in the preceding year, and continued to suckle during the following year. Estimates of M1 emergence age in australopiths are remarkably similar to the Kanyawara chimpanzees, and recent reconstructions of their life histories should be reconsidered in light of these findings. PMID:23359695

Smith, Tanya M; Machanda, Zarin; Bernard, Andrew B; Donovan, Ronan M; Papakyrikos, Amanda M; Muller, Martin N; Wrangham, Richard

2013-01-28

355

Digital versus conventional panoramic radiography in predicting inferior alveolar nerve injury after mandibular third molar removal.  

PubMed

The aim of the study was to compare the accuracy of conventional and digital panoramic radiography (OPG) in relation to 4 specific high-risk signs (interruption of the superior cortical line, diversion, narrowing of the canal, and dark band of the root), which would indicate a close anatomic relationship between third molar roots and the inferior alveolar canal.Four hundred mandibular third molar surgical removals after conventional and 272 after digital radiographs were evaluated in the study. The association between postoperative inferior alveolar nerve (IAN) paresthesia and the presence of any preoperative high-risk signs in the OPG was investigated. Bivariate and multivariate logistic regression analyses were completed to compare the accuracy of conventional and digital radiographic techniques detecting high-risk signs predicting possible IAN paresthesia.Digital OPG results showed significantly higher sensitivity in diversion (P = 0.014) and narrowing (P < 0.002) of the canal, whereas the specificity of these signs was significantly lower (P < 0.001 and P = 0.035). The likelihood ratio analysis and multivariate logistic regression analysis did not prove the significant difference between digital and conventional imaging according to the examined high-risk signs. Positive predictive values of the signs were found in conventional radiography between 3.6% and 10.9%, whereas in the digital images, it ranged from 2.9% to 7.9%.The results of this study failed to prove significant difference between the accuracy of digital and conventional OPG for predicting IAN paresthesia, whereas low positive predictive values indicate both imaging techniques as inadequate screening methods for predicting IAN paresthesia after mandibular third molar removal. PMID:22446455

Szalma, József; Lempel, Edina; Jeges, Sára; Olasz, Lajos

2012-03-01

356

Venostasis test as a method of choice to evaluate blood fibrinolytic capacity during third molar surgery.  

PubMed

(Full text is available at http://www.manu.edu.mk/prilozi). The aim of our research was to evaluate the fibrinolytic capacity during oral surgical interventions - operative extraction of semi-impacted third molars having caused blood fibrinolysis activity. With the intention of establishing the condition of the blood vessels' endothelium before oral surgical interventions, the influence of surgical procedures upon the endothelium, and the response of the endothelium after interventions, the venostasis test (venous stasis) was conducted in all the subjects. This test measures the global fibrinolytic activity of the plasma, caused by anoxia. In order to realize the aim, the first blood sample was taken before the beginning of the test, and then the indicated oral surgical intervention was performed. Immediately after the completion of the surgery, the venostasis test was carried out, lasting for five minutes, and right after the test a second sample of blood was taken. Using the method of fibrin plates, the level of the activators and inhibitors of the plasminogen was established afterwards. The average values of the pro activators and inhibitors of fibrinolysis from the venostasis test, in all subjects, showed increased values compared to the same ones in the control group, in all researched relations. Statistically, a significant difference was established after interventions were performed. These findings support the fact of possible damage to the blood vessels' endo-thelium and a change of the fibrinolytic capacity in the perioperative period of third molar surgery. Key words: third molar impaction, oral surgery, fibrinolytic system, stress. PMID:23425882

Dimova, C; Evrosimovska, B; Kovacevska, I

2012-12-01

357

Early determination and permissive expression of amelogenin transcription during mouse mandibular first molar development.  

PubMed

The expression of tissue-specific enamel matrix genes is believed to require both instructive and permissive interactions of enamel organ epithelium with dental papilla mesenchyme and/or extracellular matrix during a restricted period of development. Biosynthesis of amelogenin gene products has been found to be associated with the terminal differentiation of inner enamel organ epithelium. The developing mouse first mandibular molar was used for a detailed examination of the temporal initiation and developmental pattern of amelogenin transcription. These studies define temporally instructive versus permissive influences on amelogenin transcription. During in vivo development, amelogenin transcripts were detected in late cap (15 days in utero; E15) through bell stage (E16 through E19) mouse molar tooth formation utilizing reverse transcription coupled to polymerase chain reaction amplification. Alternatively spliced amelogenin transcripts were detected in late bell stage (E18) molars. Amelogenin transcripts were also detected in isolated late cap stage (E15) enamel organ epithelium dissected free of dental papilla mesenchyme and cultured within a substitute basement membrane gel, but not in identical cap stage enamel organ epithelium cultured on plastic or a laminin-coated filter. Amelogenin transcripts were also found in early cap stage (E14) isolated enamel organ epithelium cultured within a basement membrane gel, but were not detected in enamel organ epithelium isolated from earlier stages of odontogenesis and cultured within a basement membrane gel. The results of these experiments indicate that a basement membrane gel is a useful extracellular substrate which provides permissive interactions required for the expression of amelogenin transcripts by enamel organ epithelium and that instructive interactions which determine enamel organ epithelium to become committed to amelogenin transcription occur prior to the early cap stage (E14) of odontogenesis. The results also suggest that continued interactions of enamel organ epithelium with dental papilla mesenchyme serve to regulate amelogenin transcription and post-transcriptional amelogenin RNA splicing in a complex manner during odontogenesis. PMID:8026631

Couwenhoven, R I; Snead, M L

1994-07-01

358

C-shaped canal system in mandibular second molars: Part I--Anatomical features.  

PubMed

The purpose of this study was to investigate the anatomical features of C-shaped root canal system in mandibular second molars using micro-computed tomography (microCT). Fifty-eight extracted mandibular second molars with fused roots were collected from a native Chinese population. The teeth were scanned into layers of 0.5-mm thickness by microCT and measurements were made at eleven levels. The ratio of the depth of the deepest part of the groove to the buccal-lingual thickness of the cross-section of the root was calculated for each tooth. The canal shapes of the scanned cross-sections were assessed and classified according to a modified Melton's method. Results were subject to the Kruskal-Wallis test. Of the 58 molars, 54 had a C-shaped canal system with a mean groove-to-thickness ratio of 47.96%; the four teeth without a C-shaped canal had a mean ratio of 14.82%. Most orifices (98.1%) were found within 3 mm below the cementoenamel junction. Of teeth with a C-shape canal system, a majority demonstrated an orifice with an uninterrupted "C" configuration. Seventeen canals divided in the apical portion, most of which did so within 2 mm from the apex. The cross-sectional shape varied drastically along the length of the canal. Teeth with a high groove-to-thickness ratio had at least one section with C1, C2, or C3 configuration. The canal shape in middle and apical thirds of C-shaped canal systems could not be predicted on the basis of the shape at the orifice level. Section 2 of this paper addressed the correlation between the radiographic appearance and these microCT images. PMID:15564874

Fan, Bing; Cheung, Gary S P; Fan, Mingwen; Gutmann, James L; Bian, Zhuan

2004-12-01

359

First molar eruption, weaning, and life history in living wild chimpanzees  

PubMed Central

Understanding dental development in chimpanzees, our closest living relatives, is of fundamental importance for reconstructing the evolution of human development. Most early hominin species are believed to show rapid ape-like patterns of development, implying that a prolonged modern human childhood evolved quite recently. However, chimpanzee developmental standards are uncertain because they have never been based on living wild individuals. Furthermore, although it is well established that first molar tooth emergence (movement into the mouth) is correlated with the scheduling of growth and reproduction across primates broadly, its precise relation to solid food consumption, nursing behavior, or maternal life history is unknown. To address these concerns we conducted a photographic study of subadult chimpanzees (Pan troglodytes schweinfurthii) in Kanyawara, Kibale National Park, Uganda. Five healthy infants emerged their lower first molars (M1s) by or before 3.3 y of age, nearly identical to captive chimpanzee mean ages (?3.2 y, n = 53). First molar emergence in these chimpanzees does not directly or consistently predict the introduction of solid foods, resumption of maternal estrous cycling, cessation of nursing, or maternal interbirth intervals. Kanyawara chimpanzees showed adult patterns of solid food consumption by the time M1 reached functional occlusion, spent a greater amount of time on the nipple while M1 was erupting than in the preceding year, and continued to suckle during the following year. Estimates of M1 emergence age in australopiths are remarkably similar to the Kanyawara chimpanzees, and recent reconstructions of their life histories should be reconsidered in light of these findings.

Smith, Tanya M.; Machanda, Zarin; Bernard, Andrew B.; Donovan, Ronan M.; Papakyrikos, Amanda M.; Muller, Martin N.; Wrangham, Richard

2013-01-01

360

Inactivation of Tgfbr2 in Osterix-Cre expressing dental mesenchyme disrupts molar root formation.  

PubMed

It has been difficult to examine the role of TGF-ß in post-natal tooth development due to perinatal lethality in many of the signaling deficient mouse models. To address the role of Tgfbr2 in postnatal tooth development, we generated a mouse in which Tgfbr2 was deleted in odontoblast- and bone-producing mesenchyme. Osx-Cre;Tgfbr2(fl/fl) mice were generated (Tgfbr2(cko)) and post-natal tooth development was compared in Tgfbr2(cko) and control littermates. X-ray and ?CT analysis showed that in Tgfbr2(cko) mice radicular dentin matrix density was reduced in the molars. Molar shape was abnormal and molar eruption was delayed in the mutant mice. Most significantly, defects in root formation, including failure of the root to elongate, were observed by postnatal day 10. Immunostaining for Keratin-14 (K14) was used to delineate Hertwig's epithelial root sheath (HERS). The results showed a delay in elongation and disorganization of the HERS in Tgfbr2(cko) mice. In addition, the HERS was maintained and the break up into epithelial rests was attenuated suggesting that Tgfbr2 acts on dental mesenchyme to indirectly regulate the formation and maintenance of the HERS. Altered odontoblast organization and reduced Dspp expression indicated that odontoblast differentiation was disrupted in the mutant mice likely contributing to the defect in root formation. Nevertheless, expression of Nfic, a key mesenchymal regulator of root development, was similar in Tgfbr2(cko) mice and controls. The number of osteoclasts in the bone surrounding the tooth was reduced and osteoblast differentiation was disrupted likely contributing to both root and eruption defects. We conclude that Tgfbr2 in dental mesenchyme and bone is required for tooth development particularly root formation. PMID:23933490

Wang, Ying; Cox, Megan K; Coricor, George; Macdougall, Mary; Serra, Rosa

2013-08-08

361

Effect of submucosal and intramuscular dexamethasone on postoperative sequelae after third molar surgery: comparative study.  

PubMed

We compared the effects of dexamethasone sodium phosphate given submucosally and intramuscularly on postoperative complications after removal of impacted lower third molars in a preliminary randomised prospective clinical trial. Thirty patients, each of whom required removal of a single impacted mandibular third molar under local anaesthesia, were randomly allocated to one of 3 groups of 10 each. The 2 experimental groups were given dexamethasone 4 mg submucosally or intramuscularly, and the control group had no steroid. Facial swelling and maximal interincisal distance were measured by an independent examiner at baseline (preoperatively), and at 1, 3, and 7 days postoperatively. Pain was measured by counting the number of rescue analgesic tablets taken, and from the patients' response to a visual analogue scale (VAS). The mean age of the 16 men and 14 women was 27 years (range 20-48). Both dexamethasone groups showed significant reductions in swelling (p<0.001) and in pain (p<0.05) compared with the control group at all intervals. Submucosal dexamethasone resulted in significantly less trismus than controls on day 1 postoperatively (p=0.04), but there were no significant differences among the groups at the other times. The effects of the two routes of dexamethasone were comparable for all variables. There were no cases of alveolar osteitis or wound infection. Dexamethasone 4 mg given submucosally is an effective way of minimising swelling, trismus, and pain after removal of impacted lower third molars, and is comparable with the intramuscular route. It offers a simple, safe, painless, non-invasive, and cost-effective treatment in moderate and severe cases. PMID:21035237

Majid, Omer Waleed; Mahmood, Waseem Khalid

2010-10-29

362

Radiographic Evaluation of Third Molar Development in 5- to 25 Year Olds in Tehran, Iran  

PubMed Central

Objective: Radiographic evaluation of the third molar tooth to determine its position and degree of development is an important part in diagnosis and treatment planning, as well as in forensic dentistry procedures. The objective was to investigate the developmental stages of third molars in relation to chronologic age, gender and location (maxillary/mandibular) in an Iranian population. Materials and Methods: The data were collected in departments of pediatric dentistry and orthodontics, Tehran Faculty of Dentistry and four private offices. Three calibrated observers visited the centers to examine panoramic radiographs and corresponded patients documents in each age cohort in the range of 5- to-25-years old. Data were analyzed by Generalized Estimating Equation (GEE) in the linear mode and exchangeable correlation structure. The significance level was defined as 0.05. Results: The mean age of emerging third molars’ follicle was 9.29±1.65 years. Early calcification was seen at the mean age of 10.28±1.66 years. The GEE model controlling for age, gender and tooth location (maxillary/mandibular) revealed that besides age (?=0.43, p<0.001), the tooth location had association with the developmental stage (?=0.11, p<0.001) so that maxillary teeth were prior in calcification stages, but no relationship between gender and developmental stages was seen (?=0.03, p=0.69). Conclusion: Maxillary teeth were ahead of mandibular teeth in calcification stages with no gender difference. The present study may provide a reference for oral surgeons, pediatric dentists and orthodontists practicing in Iran and may have implications for the neighboring countries especially those with Caucasian populations.

Jafari, A.; Mohebbi, SZ.; Khami, MR.; Shahabi, M. Shakur; Naseh, M.; Elhami, F.; Shamshiri, AR.

2012-01-01

363

Accidental ingestion of molar band and its management: maintenance is better than management.  

PubMed

Ingestion of a broken part of fixed orthodontic appliance is a potential complication during orthodontic treatment. We report a case of accidental ingestion of molar band and its subsequent diagnosis followed by endoscopic retrieval method. Although prevention of such incidence is the best method at the same time management of such an event is also crucial. The objective of this paper is to draw attention to the potentially serious complications that can occur if preventive techniques are not practiced and also the management of such event. PMID:23476819

Naragond, Appasaheb; Kenganal, Smitha; Rajasigamani, K; Kumar, N Sathish

2013-02-06

364

Prediction of excess molar volumes of binary mixtures of organic compounds from refractive indices  

Microsoft Academic Search

The excess molar volumes of 51 binary mixtures containing diverse groups of organic compounds: alcohols (methanol, ethanol,\\u000a propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol, and heptan-1-ol), (cyclo-) alkanes (hexane, heptane, octane, nonane, decane,\\u000a undecane, dodecane, and cyclohexane), esters (diethyl carbonate and ethyl chloroacetate), aromatics (o-xylene, m-xylene, p-xylene, and ethylbenzene), ketones (acetone), and ethers (anisole), were predicted from the refractive index data, using\\u000a three

Ivona R. Radovi?; Mirjana Lj. Kijev?anin; Marijan Z. Gabrijel; Slobodan P. Šerbanovi?; Bojan D. Djordjevi?

2008-01-01

365

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

366

Treatment of dentoskeletal bimaxillary protrusion: additional extraction of maxillary second molars.  

PubMed

This case report describes the orthodontic treatment of an 18-year-old female patient with Class II malocclusion with dentoskeletal bimaxillary protrusion. An acceptable treatment result was obtained with a four first premolar extraction and an additional maxillary two second molar extraction plan. Standard edgewise appliances were placed after the premolars were extracted. A positive soft tissue response to treatment was achieved, and the patient's profile was improved, with a reduction of lip protrusion and mentalis strain. Dentally, the interincisal angle improved significantly as both the maxillary and mandibular incisors were uprighted after space closure. The occlusion remained stable during 2 years of follow-up. PMID:19639455

Iijima, Shigeki; Yoshida, Mitsuru; Terada, Kazuto

2009-07-29

367

Unerupted Primary Molar Teeth Positioned Inferior to the Permanent Premolar: A Case Report  

PubMed Central

Primary tooth impaction is a rare finding during the development of primary dentition. Several factors contribute to the impaction of a deciduous tooth. This report describes the diagnosis and treatment of a 10-year-old boy who presented an impacted second primary mandibular molar. This tooth, located inferior to the second premolar together with an odontoma, was positioned superior to the premolar teeth. Treatment consisted of surgical removal of the impacted deciduous tooth and odontoma and placement of a passive lower lingual holding arch. Periodic examination was indicated for follow-up. Early intervention was recommended to manage orofacial disfigurement and to avoid consequent problems.

Memarpour, M.; Rahimi, M.; Bagheri, A.; Mina, K.

2012-01-01

368

Primary and secondary closure technique following removal of impacted mandibular third molars: A comparative study  

PubMed Central

Aim: The purpose of this study was to evaluate and compare the post operative healing, using primary versus second closure techniques after impacted mandibular third molar removal. Materials and Methods: The study consisted of twelve patients, Seven males and five females under 30 years of age were divided into two groups as Group A and Group B in the randomized fashion. In the Group A, closure was done by primary intention and in the Group B, by secondary closure. A comparison between both groups was done with a follow-up period of 6 h to 6 days with regards to postoperative pain and swelling. Results: The statistical analysis (analysis of variance for repeated measures, P < 0.05) showed that pain was greater in Group A, although it decreased over time similarly in the two groups. Pain and swelling was less severe with secondary healing than with primary healing. Conclusion: The outcome of this study suggested that secondary closure technique is better than primary closure technique for removal of impacted mandibular third molar with regards to postoperative pain and swelling.

Chaudhary, Manoj; Singh, Manpreet; Singh, Sanjay; Singh, S. P.; Kaur, Gagandeep

2012-01-01

369

On a relationship between molecular polarizability and partial molar volume in water  

NASA Astrophysics Data System (ADS)

We reveal a universal relationship between molecular polarizability (a single-molecule property) and partial molar volume in water that is an ensemble property characterizing solute-solvent systems. Since both of these quantities are of the key importance to describe solvation behavior of dissolved molecular species in aqueous solutions, the obtained relationship should have a high impact in chemistry, pharmaceutical, and life sciences as well as in environments. We demonstrated that the obtained relationship between the partial molar volume in water and the molecular polarizability has in general a non-homogeneous character. We performed a detailed analysis of this relationship on a set of ~200 organic molecules from various chemical classes and revealed its fine well-organized structure. We found that this structure strongly depends on the chemical nature of the solutes and can be rationalized in terms of specific solute-solvent interactions. Efficiency and universality of the proposed approach was demonstrated on an external test set containing several dozens of polyfunctional and druglike molecules.

Ratkova, Ekaterina L.; Fedorov, Maxim V.

2011-12-01

370

Update on coronectomy. A safer way to remove high risk mandibular third molars.  

PubMed

Decoronation of high risk mandibular third molars (M3Ms) has become common practice in parts of UK and USA. With the introduction of Cone Beam CT scanning, there has been an evolution in the practice, with avoidance of unnecessary coronectomies based on CBCT findings. Also, additional anatomical features found only on CBCTs have introduced possible additional indications to undertake intentional coronectomy. Trigeminal nerve injury is the most problematic consequence of dental surgical procedures with major medico-legal implications. Iatrogenic injuries to the third division of the trigeminal nerve remain a common and complex clinical problem. Altered sensation and pain in the orofacial region may interfere with speaking, eating, kissing, shaving, applying make-up, toothbrushing and drinking; namely just about every social interaction we take for granted. Usually after oral rehabilitation, the patient expects and experiences significant improvements, not only regarding jaw function, but also in relation to dental, facial, and even overall body image. Thus these injuries have a significant negative effect on the patient's self-image and quality of life and the iatrogenesis of these injuries lead to significant psychological effects. Clinical Relevance: Coronectomy is an alternative procedure to complete removal of a mandibular third molar in situations where there is high risk of damage to the inferior alveolar nerve. PMID:23909229

Renton, Tara

2013-06-01

371

Evaluation of intra-alveolar chlorhexidine dressings after removal of impacted mandibular third molars.  

PubMed

Chlorhexidine gluconate (CHX) has been investigated for its possible benefit in the prevention of alveolar osteitis complicating third molar removal. In a double-blind, placebo-controlled clinical study, 70 randomly selected healthy patients were subjected to uncomplicated mandibular third molar removal followed by CHX-gelatin sponge and saline solution-gelatin sponge intra-alveolar dressings. Each patient was followed for 6 days for postoperative discomfort and complications, and scored accordingly. The results demonstrated that patients receiving 0.2% CHX intra-alveolar dressings exhibited a significant reduction in postoperative discomfort and complications when compared with saline solution-treated control sites (p less than 0.005). Further, this phenomenon was not found to be related to patient factors including age, sex, and race, nor did any correlation exist between treated or control sites, and surgical factors including performing surgeon, surgeon's dominant hand, time of surgery, surgical site, and difficulty of the removal. These findings warrant further studies concerning the apparent clinical benefit of postextraction intra-alveolar CHX dressings for the reduction of postoperative alveolar osteitis. PMID:1545974

Fotos, P G; Koorbusch, G F; Sarasin, D S; Kist, R J

1992-03-01

372

The chronology of second molar development in Brazilians and its application to forensic age estimation  

PubMed Central

Purpose This study investigated the possible correlation between the mineralization of the second molars and the chronological age of a sample population of the state of Paraiba, Brazil. Materials and Methods One thousand eight hundred fifty-four digitized panoramic images using a scanner of a private dental radiology service were obtained in six months. Of these, 457 were selected from patients aged 4.6 to 16 years who met certain criteria. The images were assessed twice by a radiologist with 5 years experience. A minimum interval of 30 days between the evaluations of the same patient was established. To analyze the relationship between chronological age, calcification level proposed by Demirjian et al in 1973, gender, and tooth, a multiple linear regression model was adjusted, taking age as the response variable (p<0.05). Results The gender and calcification level were significantly correlated with the age of the patients (p<0.05). There was a significant difference between the average age of the patients' upper teeth compared to the lower ones in both genders (p<0.05). The dental development occurred earlier in female individuals than in male ones, and there was no significant difference between the right and left second permanent molars. Conclusion It was observed that ethnic variables are related to certain parameters of age and sex identification in the Brazilian population, providing important information for forensic evaluations.

Pontual, Andrea dos Anjos; Beltrao, Rejane Targino; Beltrao, Ricardo Villar; Pontual, Maria Luiza dos Anjos

2013-01-01

373

Disruptions of the pulp-dentin complex in an investigated case of pink secondary retained molar.  

PubMed

A pink retained left mandibular first molar without carious lesions was diagnosed in a healthy 12-year-old girl presenting normal clinical tests. An orthopantomogram failed to detect other retained teeth. Both periapical radiography and computed tomography showed the absence of a periodontal ligament space in the bifurcation area and the presence of radiolucency or calcifications in the pulp cavity. The coronal part of the removed tooth was subjected to histological and immunohistochemical analysis using anti-PCNA (proliferation marker) and anti-p53 (apoptosis marker) antibodies. Root surfaces were observed by scanning electron microscopy. The pink color of the molar reflected the extension of resorptive tissue into the clinical crown and the underlining proliferation of pulp vessels. Ankylosis observed in the bifurcation area was also detected in the coronal part of the pulp. Whereas odontoblasts secreted tertiary dentin despite no evidence for a carious lesion, only osteocytes in the newly formed bone were apoptotic and the root surfaces were free of resorption lacunae. The etiopathology of the lesion in this case indicated a pulp origin, suggesting that new therapies targeting this tissue should be developed. PMID:20652799

Roy, Véronique; Jamazi, Imene; Jemmali, Badiaa; Ghoul-Mazgar, Sonia

2010-07-23

374

Molar Incisor Hypomineralization: A Study of Prevalence and Etiology in a Group of Iranian Children  

PubMed Central

Objective The aim of this study was to investigate the prevalence of molar incisor hypomineralization (MIH) and its relationship with systemic conditions in a group of Iranian children. Methods The study population comprised of 433 7-9 year olds, from four schools in Zahedan, Iran. Subjects were evaluated clinically by one examiner, and at a separate session, their mothers completed a coded medical history questionnaire. Hypo-mineralized molars and incisors were recorded based on DDE (developmental defects of enamel) index and DMFT (number of decayed, filled and missing teeth) was determined. Statistical analyses were performed using Chi-square and independent sample t-tests. Findings Fifty-five (12.7%) children showed MIH. The overall mean number of affected teeth was 0.2. The mean value of DMFT in MIH children was greater than in normal children. Demarcated opacities were the most frequent (76%) enamel defect. Mother's and child's medical problems during prenatal, perinatal and post natal period were significantly remarkable in MIH children. Conclusion The prevalence of MIH in a group of Iranian children was 12.7%. Prenatal, perinatal and post natal medical conditions were more prevalent in children affected by MIH.

Ahmadi, Rahil; Ramazani, Nahid; Nourinasab, Rahmatollah

2012-01-01

375

Monitoring helical twists and effective molarities in dinuclear triple-stranded lanthanide helicates.  

PubMed

The replacement of terminal benzimidazole-pyridine binding units in the neutral di-tridentate segmental ligand L1 with phenanthroline in L10 reduces the number of torsional degrees of freedom by two units. Reactions of these ligands with trivalent europium or lutetium cations yield structurally similar self-assembled dinuclear triple-stranded [Ln?(Lk)?]?? complexes, thus demonstrating that the increased rigidity of the strand in L10 is compatible with its helical twist. With the larger lanthanum cations, the metallic coordination spheres are completed with two terminal axial triflate counter-anions to give [La?(L10)?(CF?SO?)?]??. Thermodynamic investigations in acetonitrile confirm the minor constraints produced by the planar phenanthroline unit in L10 leading to comparable effective molarities EMEu,L1 ? EMEu,L10 = 10-3.9(4) M with mid-range EuIII cations. The striking minute effective molarities EMLn,Ln-2H ? 10??-10?? M obtained upon the replacement of terminal phenanthrolines with structurally analogous fused hydroxyquinolines in L9 can be thus unambiguously assigned to solvation effects, a new tool for controlling complexity in metal-induced self-assembly processes. PMID:23695775

Ryan, Patrick E; Guénée, Laure; Piguet, Claude

2013-08-21

376

Root and root canal morphology of the human permanent maxillary first molar: a literature review.  

PubMed

The objective of this study was to review the literature with respect to the root and canal systems in the maxillary first molar. Root anatomy studies were divided into laboratory studies (in vitro), clinical root canal system anatomy studies (in vivo) and clinical case reports of anomalies. Over 95% (95.9%) of maxillary first molars had three roots and 3.9% had two roots. The incidence of fusion of any two or three roots was approximately 5.2%. Conical and C-shaped roots and canals were rarely found (0.12%). This review contained the most data on the canal morphology of the mesiobuccal root with a total of 8399 teeth from 34 studies. The incidence of two canals in the mesiobuccal root was 56.8% and of one canal was 43.1% in a weighted average of all reported studies. The incidence of two canals in the mesiobuccal root was higher in laboratory studies (60.5%) compared to clinical studies (54.7%). Less variation was found in the distobuccal and palatal roots and the results were reported from fourteen studies consisting of 2576 teeth. One canal was found in the distobuccal root in 98.3% of teeth whereas the palatal root had one canal in over 99% of the teeth studied. PMID:16934622

Cleghorn, Blaine M; Christie, William H; Dong, Cecilia C S

2006-06-30

377

A Comparison of four pulpotomy techniques in primary molars: a long-term follow-up.  

PubMed

The study evaluated the effects of formocresol (FC), ferric sulphate (FS), calcium hydroxide (Ca[OH](2)), and mineral trioxide aggregate (MTA) as pulp dressing agents in pulpotomized primary molars. Sixteen children each with at least four primary molars requiring pulpotomy were selected. Eighty selected teeth were divided into four groups and treated with one of the pulpotomy agent. The children were recalled for clinical and radiographic examination every 6 months during 2 years of follow-up. Eleven children with 56 teeth arrived for clinical and radiographic follow-up evaluation at 24 months. The follow-up evaluations revealed that the success rate was 76.9% for FC, 73.3% for FS, 46.1% for Ca(OH)(2), and 66.6% for MTA. In conclusion, Ca(OH)(2)is less appropriate for primary teeth pulpotomies than the other pulpotomy agents. FC and FS appeared to be superior to the other agents. However, there was no statistically significant difference between the groups. PMID:18634926

Sonmez, Deniz; Sari, Saziye; Cetinba?, Tu?ba

2008-08-01

378

Histopathologic evaluation of follicular tissues associated with impacted lower third molars  

PubMed Central

Context: Previous studies have reported that the dental follicular tissues associated with impacted lower third molars (ILTMs) may undergo cystic degeneration and/or neoplastic transformation. This is especially likely when the pericoronal space is >2.5 mm on intraoral radiographs and >3 mm on panoramic radiographs and to examine dental follicular tissue for pathological changes in patients with ILTMs and pericoronal radiolucencies of <2.5 mm. Aim: Histopathological evaluation of follicular tissues associated with ILTMs. Materials and Methods: The morphology of the hematoxylin and eosin-stained follicular tissues of 146 such impactions were studied. Results: On microscopy, no cystic structures with fibrous walls were identified. 85 cases (58%) showed fibrous or myxomatous connective tissue and no epithelial elements. 61 cases (42%) showed epithelial elements in addition to fibrocollagenous tissue. Of these, 16 cases exhibited epithelium, of which 13 cases showed reduced enamel epithelium and three cases showed squamous metaplasia/non-keratinized stratified squamous epithelium. Conclusions: All asymptomatic unerupted third molars with pericoronal radiolucency of <2.5 mm should be retained since they do not exhibit cyst formation microscopically.

Tegginamani, Anand S; Prasad, Rajendra

2013-01-01

379

Synthesization of Nanostructured Titanium Dioxide at Low Molarity of Sol-Gel Process  

NASA Astrophysics Data System (ADS)

Titanium dioxide, TiO2 is one of the semiconductor materials. The aim of this paper is to determine the production of TiO2 by sol-gel method. The sol-gel method used because this method is quite simple compare to other methods such as dip-coated and refractive sputtering. The parameter will be used in this paper is the concentration. The sol-gel TiO2 solution then spin coated on the glass substrate to form homogenous and transparent thin film. The thin film was coated at 8 layers to adjust the refractive index characteristics and to get the clear images during characterize by spin coating technique. Other than that, this work also to get the band gap energy similar to the standard bandgap for TiO2. The optical properties such as absorption and transmittance of TiO2 can be done by Ultraviolet-visible Spectroscopy (UV-Vis). The changes on the surface morphology were observed using Atomic Force Microscopy (AFM), Field Emission Scanning Electron Microscopy (FESEM). Based on the result, higher the molarity of TiO2, the uniformity of the surface morphology, and the energy bandgap is much better. Higher the molarity, the bandgap will be lower with 0.1M (3.78 eV) and its too large compare to the standard value (3.2 eV).

Maarof, S. K. M.; Abdullah, S.; Rusop, M.

2013-06-01

380

Refractive index, molar refraction and comparative refractive index study of propylene carbonate binary liquid mixtures.  

PubMed

Refractive indices (n) have been experimentally determined for the binary liquid-liquid mixtures of Propylene carbonate (PC) (1) with benzene, ethylbenzene, o-xylene and p-xylene (2) at 298.15, 303.15 and 308.15 K over the entire mole fraction range. The experimental values of n are utilised to calculate deviation in refractive index (?n), molar refraction (R) and deviation in molar refraction (?R). A comparative study of Arago-Biot (A-B), Newton (NW), Eyring and John (E-J) equations for determining refractive index of a liquid has been carried out to test their validity for all the binary mixtures over the entire composition range at 298.15 K. Comparison of various mixing relations is represented in terms of average deviation (AVD). The ?n and ?R values have been fitted to Redlich-Kister equation at 298.15 K and standard deviations have been calculated. The results are discussed in terms of intermolecular interactions present amongst the components. PMID:24061238

Wankhede, Dnyaneshwar Shamrao

2012-06-01

381

Abrasive, Silica Phytoliths and the Evolution of Thick Molar Enamel in Primates, with Implications for the Diet of Paranthropus boisei  

PubMed Central

Background Primates—including fossil species of apes and hominins—show variation in their degree of molar enamel thickness, a trait long thought to reflect a diet of hard or tough foods. The early hominins demonstrated molar enamel thickness of moderate to extreme degrees, which suggested to most researchers that they ate hard foods obtained on or near the ground, such as nuts, seeds, tubers, and roots. We propose an alternative hypothesis—that the amount of phytoliths in foods correlates with the evolution of thick molar enamel in primates, although this effect is constrained by a species' degree of folivory. Methodology/Principal Findings From a combination of dietary data and evidence for the levels of phytoliths in plant families in the literature, we calculated the percentage of plant foods rich in phytoliths in the diets of twelve extant primates with wide variation in their molar enamel thickness. Additional dietary data from the literature provided the percentage of each primate's diet made up of plants and of leaves. A statistical analysis of these variables showed that the amount of abrasive silica phytoliths in the diets of our sample primates correlated positively with the thickness of their molar enamel, constrained by the amount of leaves in their diet (R2?=?0.875; p<.0006). Conclusions/Significance The need to resist abrasion from phytoliths appears to be a key selective force behind the evolution of thick molar enamel in primates. The extreme molar enamel thickness of the teeth of the East African hominin Paranthropus boisei, long thought to suggest a diet comprising predominantly hard objects, instead appears to indicate a diet with plants high in abrasive silica phytoliths.

Rabenold, Diana; Pearson, Osbjorn M.

2011-01-01

382

Effects of maxillary molar intrusion on the nasal floor and tooth root using the skeletal anchorage system in dogs.  

PubMed

The skeletal anchorage system (SAS) was developed to provide intraoral absolute anchorage for the intrusion or distalization of molars. The purpose of this study was to verify the effects of remarkable molar intrusion on the tooth root and the maxillary sinus floor. Six adult female beagles with fully erupted dentition were used. Titanium miniplates were implanted bilaterally above the maxillary second premolar root apices using pentobarbital anesthesia. The second premolars were intruded for four or seven months after three months of healing after implantation. Standardized dental radiographs were taken periodically to evaluate the amount of tooth movement and root resorption. After the experimental animals were fixed by perfusion at the end of each experimental period, the second premolars were dissected along with the surrounding alveolar bone. Undecalcified (60 microm thick) and decalcified (five microm thick) sections were prepared. The average extent of intrusion was 1.8 mm after four months and 4.2 mm after seven months. The root apices of the intruded molars penetrated into the nasal cavity. Remodeled bone around the intruded molar toots was rich in woven bone on the buccal side, whereas that on the palatal side was rich in lamellar bone. Nasal floor membrane and a thin layer of newly formed bone, which lifted intranasally, covered the intruded molar root. Root resorption partly reached into the dentine without the formation of reparative cementum, and little or no serious pathological changes were seen in the pulp of the intruded molars. SAS effectively intruded maxillary molars, but some moderate root resorption was observed. PMID:12725372

Daimaruya, Takayoshi; Takahashi, Ichiro; Nagasaka, Hiroshi; Umemori, Mikako; Sugawara, Junji; Mitani, Hideo

2003-04-01

383

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

2008-09-27

384

Expression patterns of RNAs for amelin and amelogenin in developing rat molars and incisors.  

PubMed

We have recently identified a novel RNA sequence in ameloblasts, coding for amelin (Cerny et al., 1996). In the present paper, its expression has been compared with that of amelogenin in developing incisors and molars of rats, by means of in situ hybridization of paraffin sections. The RNAs for both amelin and amelogenin were highly expressed in secretory ameloblasts. The expression of RNA for amelogenin gradually decreased in the post-secretory ameloblasts. In contrast, the RNA expression for amelin remained high in post-secretory ameloblasts up to the stage of fusion between dental and oral epithelia at the time of tooth eruption. We suggest that amelin might be involved in the mineralization of enamel or in the attachment of ameloblasts to the enamel surface. The whole-mount in situ hybridization procedure is described for the first time in dental research. It proved to be a useful method and confirmed the results of the conventional in situ hybridization. PMID:9206337

Fong, C D; Hammarström, L; Lundmark, C; Wurtz, T; Slaby, I

1996-11-01

385

Bubble curves and saturated liquid molar volumes for chlorofluorohydrocarbon-hydrocarbon mixtures: Experimental data and modeling  

Microsoft Academic Search

Vapor-liquid equilibria and liquid densities were obtained using a static apparatus fitted with a variable-volume cell which was described in detail by Valtz et al. (1). Results are given at four temperatures for the binary systems butane--1,2,2-trichlorotrifluoroethane, pentane--1,2-dichloro-1,1,2,2-tetrafluoroethane, hexane--1,2-dichloro-1,1,2,2-tetrafluoroethane, heptane--1,12-trichloro-1,2,2-trifluoromethane, heptane--1,2-dichloro-1,1,2,2-tetrafluoroethane, and benzene--1,2-dichloro-1,1,2,2-tetrafluoroethane and the ternary system 1,2-dichloro-1,1,2,2-tetrafluoroethane--1,1,2-trichloro-1,2,2-trifluoromethane--heptane. The best simultaneous representation of pressures and saturated liquid molar volumes at

Serge Laugier; Dominique Richon; Henri Renon

1994-01-01

386

Fracture Resistance of Non-Metallic Molar Crowns Manufactured with CEREC 3D  

NASA Astrophysics Data System (ADS)

Objectives. To compare fracture strength and fatigue resistance of ceramic (ProCAD, Ivoclar-Vivadent) (C) and resin composite (Paradigm MZ100, 3M/ ESPE) (R) crowns made with CEREC-3D. Methods. A prepared ivorine molar tooth was duplicated to produce 40 identical prepared specimens made of epoxy resin (Viade). Twenty (C) crowns and 20 (R) were cemented to their dies using resin cement. Ten of each group were subjected to compressive loading to fracture. The remaining 10 of each group were subjected to mechanical cyclic loading for 500,000 cycles. The survivors were subjected to compressive loading to fracture. Results. No significant difference in mean fracture load was found between the two materials. However, only 30% of the (C) crowns vs. 100% of the (R) crowns survived the cyclic loading test. Conclusions. (R) crowns demonstrated higher fatigue Resistance than (C) crowns in-vitro and might better resist cracking in-vivo.

Madani, Dalia A.

387

The comprehensive characteristics of quaternary AlInGaN with various TMI molar rate  

NASA Astrophysics Data System (ADS)

We demonstrated very thick (~400 nm) AlInGaN quaternary alloy grown on GaN epilayer by MOCVD. The Optical, electronic, crystalline quality and surface morphology of AlInGaN/GaN hetero structures with various TMI molar flow rate were be extensively discussed. With Al0.89In0.02GaN/GaN fully lattice matched structure, less and small V-defect pits and good crystal quality comparing with the other lattice mismatched AlInGaN/GaN hetero-structures were discovered. Finally, the difference AlInGaN quaternary epilayers could be directly applied to high power LED structure in the future by the same barrier growth conditions.

Yu, Sheng-Fu; Chang, Shoou-Jinn; Chang, Sheng-Po; Lin, Ray-Ming

2010-02-01

388

Joubert syndrome: the molar tooth sign of the mid-brain.  

PubMed

Joubert syndrome (JS) is a very rare, autosomal-recessive condition. It is characterized by agenesis of cerebellar vermis, abnormal eye movements with nystagmus, episodes of hyperpnea and apnea, delayed generalized motor development, retinal coloboma and dystrophy and, sometimes, multicystic kidney disease. The importance of recognizing JS is related to the outcome and its potential complications. Prenatal diagnosis by ultarsonography and antenatal magnetic resonance imaging (MRI) is also possible. We have diagnosed a case of JS in a male infant with history of delayed mental and motor milestone development, history of abnormal breathing pattern, abnormal limb movement, generalized hypotonia and abnormal head movements with nystagmus. MRI showed hypoplastic cerebellar vermis with hypoplasia of the superior cerebellar peduncle resembling the "Molar Tooth Sign" in the mid-brain. PMID:23919210

Nag, C; Ghosh, M; Das, K; Ghosh, Tn

2013-04-01

389

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

2007-02-23

390

Characterization of cellulose acetates according to DS and molar mass using two-dimensional chromatography.  

PubMed

A two-dimensional liquid chromatographic method (2D LC) was developed to analyze the heterogeneities of cellulose acetates (CA) in the DS-range DS=1.5-2.9 with respect to both, molar mass and degree of substitution (DS). The method uses gradient liquid chromatography (HPLC) as the first dimension in order to separate by DS followed by separation of the different fractions by size (SEC) in the second dimension. The 2D experiments revealed different correlations between gradient and SEC elution volume. These correlations might arise from differences in the synthetic conditions. The newly developed 2D LC separation therefore provides new insights into the heterogeneity of CAs. PMID:24053824

Ghareeb, Hewa Othman; Radke, Wolfgang

2013-08-06

391

Root canal anatomy of mandibular second molars. Part II. C-shaped canals.  

PubMed

The root canal anatomy of 19 mandibular second molars with C-shaped canals was investigated by rendering the roots transparent and allowing the canal system to be observed by black ink infiltration. The presence of three root canals was most frequent, and lateral canals were found in all roots. Transverse anastomoses were found in 15 of the 19 roots. The apical foramen was most commonly situated away from the apex, and apical deltas were found in 16 of the 19 roots. The C-shaped canals were found more frequently in Asians than in other racial groups (P less than 0.02). The formation of C-shaped roots and their racial predilection is discussed. A case report of the root canal treatment of a C-shaped canal is included and suggestions are made concerning suitable procedures for use in root canal treatment of these complex canal systems. PMID:2391180

Manning, S A

1990-01-01

392

Morphology of apical foramen in permanent molars and premolars in a Turkish population.  

PubMed

Abstract Objective: To determine the number, shape and diameter of minor apical foramina, the distance between apical foramina and anatomical apex and the frequency of accessory foramina in a Turkish population. Materials and methods: Eight hundred permanent maxillary and mandibular teeth were collected. The roots were stained with methylene blue and the apices were examined with a stereomicroscope (×40) and transferred to a computer to perform the measurements using Adobe Photoshop software. Results: The incidence of one apical foramen was highest in distobuccal roots of the maxillary first molars and was lowest in the maxillary first premolars with single roots. The distance of deviation in all the teeth was between 0.271-0.519 mm. The frequency of accessory foramina was between 30-70% for the various tooth types. Conclusions: The results of this in vitro study indicate that the morphology of apical foramina in this Turkish population may present highly complex anatomical variations. PMID:23270574

Ayranci, L Benan; Yeter, Kübra Y; Arslan, Hakan; Kseo?lu, Mustafa

2012-12-28

393

In vivo and in vitro study of /sub 90/Sr in developing rat molar enamel  

SciTech Connect

The uptake patterns of /sub 90/Sr in developing rat molar enamel were studied in vivo and in vitro. Autoradiographic methods were used that preclude loss or translocation of tracers associated with water-soluble compounds in the sections. In eight-day-old rats injected with the tracer, /sub 90/Sr uptake in the enamel was significantly less than for dentin and bone, particularly at early sacrifice times. The uptake pattern of 90Sr was somewhat different from that previously observed for /sub 45/Ca. The in vitro experiments indicated that the viable intact enamel organ limits uptake of /sub 90/Sr by enamel in both the secretory and maturation phases of enamel formation.

White, B.A.; Deaton, T.G.; Bawden, J.W.

1980-12-01

394

Multiple melting peak analysis with gel-spun ultra-high molar mass polyethylene  

SciTech Connect

The multiple melting peaks observed on differential scanning calorimetry (DSC) of ultrahigh molar-mass PE fibers are analyzed as a function of sample mass. Using modern DSC capable of recognizing single fibers of microgram size, it is shown that the multiple peaks are in part or completely due to sample packing. Loosely packed fibers fill the entire volume of the pan with rather large thermal resistance to heat flow. On melting, the fibers contract and flow to collect ultimately at the bottom of the pan. This process seems to be able to cause an artifact of multistage melting dependent on the properties of the fibers. A method is proposed to greatly reduce, or even eliminate, errors of this type. The crucial elements of the analysis of melting behavior and melting temperature are decreasing the sample size and packing the individual fibers in a proper geometry, or to introduce inert media to enhance heat transport.

Boller, A.; Wunderlich, B. [Tennessee Univ., Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States)

1996-12-31

395

Unified analysis of noncomparative methods for measuring the molar absorptivity of triplet-triplet transitions  

SciTech Connect

Noncomparative techniques for the measurement of the molar absorptivity of triplet-triplet absorption transitions, epsilon/sub T/*, are reviewed. The methods covered include singlet depletion, total depletion, intensity variation (and its pulsed analog), partial saturation, and the so-called kinetic method. A critical analysis of the conceptual foundations of these varied approaches is performed. The fundamental equations of each technique are derived from a general three-state kinetic model of excitation and decay. From this unified approach it becomes very clear where assumptions are made in the traditional derivations of the methods. Additionally, one comparative method, that termed relative actinometry, is discussed, since it may be treated in a unimolecular fashion consistent with the above approach. The only major epsilon/sub T/* method excluded from this review is that involving intermolecular energy transfer, a technique which has been thoroughly documented elsewhere.

Carmichael, I.; Hug, G.L.

1987-08-01

396

Raman studies of hydration of hydroxy complexes and the effect on standard partial molar heat capacities  

NASA Astrophysics Data System (ADS)

Raman spectroscopic studies of aqueous hydroxy complexes B(OH) 3 , B(OH) 4 2- , Al(OH) 4 - , Zn(OH) 4 2- , and their deuterated analogues provide compelling evidence for the presence of strong hydrogen bonding of water in the outer solvation sphere to the oxygen of the hydroxy ligand in the first coordination sphere. The deuterated complexes are more strongly hydrogen bonded than the hydrogen complexes. The fact that these hydrogen-bonding effects for the hydroxy borates are much more pronounced than for the aluminate and zincate anions can account for the unexpectedly large differences in the standard partial molar heat capacities of B(OH) 4 - and A1(OH) 4 - . The extension of semi-empirical solvation models based on the Born approximation for aqueous hydrolyzed species will need to consider the rather large and specific effect of hydrogen bonding of water to the hydroxide ion.

Brooker, Murray H.; Tremaine, Peter R.

1992-06-01

397

The C-shaped mandibular second molar: incidence and other considerations. Members of the Arizona Endodontic Association.  

PubMed

Although its most common configuration is two roots and three canals, the mandibular second molar may have many different combinations. Cooke and Cox were the first to describe a single-rooted mandibular second molar with a continuous slit connecting some or all of the canals. If sectioned horizontally through the main portion of the root, this slit had the shape of the letter "C." Other papers were written and lectures were presented on this and similar entities, but its frequency and significance have remained the object of speculation because large numbers of these teeth have not been categorized. By combining the efforts of an endodontic study club, 811 endodontically treated mandibular second molars were evaluated. Sixty-two of these (7.6%) were identified as C-shapes. Other aspects of this configuration were also investigated. PMID:9641116

Weine, F S

1998-05-01

398

Dilemmas pertaining to three canals in the mesiobuccal root of a maxillary second molar: a case report  

PubMed Central

The mesiobuccal root of the maxillary molars is well known to pose a hindrance during endodontic therapy. Presented here is a case of a maxillary left second molar where three canals were located in its mesiobuccal root with the use of visual and diagnostic aids. Difficulties encountered during the process of unveiling the tooth's internal anatomy were discussed. The dilemmas encountered pertained to the root canal configuration, the nomenclature of the extra canals, and the justification for the presence of a third canal. The root canal configuration of 3-2-1 was confirmed for the mesiobuccal root using information gained from clinical, radiographic, and multi-detector computed tomography (MDCT) scan findings. This case demonstrates the need for efforts to locate extra canals in the mesiobuccal root of the maxillary molars as their internal anatomy remains a mystery.

Acharya, Shashi Rashmi; Saraswathi, Muliya Vidya; Sharma, Padmaja; Ather, Amber

2013-01-01

399

Practice-based clinical evaluation of metal-ceramic and zirconia molar crowns: 3-year results.  

PubMed

This practice-based study evaluates the clinical performance of conventionally luted metal-ceramic and zirconia molar crowns fabricated with pronounced anatomical core design and a prolonged cooling period of the veneering porcelain. Fifty-three patients were treated from 07/2008 until 07/2009 with either metal-ceramic crowns (MCC) (high-noble alloy + low-fusing porcelain) or zirconia crowns (Cercon System, DeguDent, Germany). Forty-nine patients (30 women/19 men) with 100 restorations (metal-ceramic: 48/zirconia: 52, mean observational period: 36·5 ± 6 months) participated in a clinical follow-up examination and were included in the study. Time-dependent survival (in situ criteria), success (event-free restorations) and chipping rates (defects of the veneering ceramics) were calculated according to the Kaplan-Meier method and analysed in relation to the crown fabrication technique, using a Cox regression model (P < 0·05). Three complete failures (metal-ceramic: 1, zirconia: 2) were recorded (survival rate after 3 years: metal-ceramic: 97·6%, zirconia: 95·2%). Of the metal-ceramic restorations, 90·9% remained event-free (two ceramic fractures, one endodontic treatment), whereas the success rate for the zirconia was 86·8% (two ceramic fractures, one endodontic treatment, one secondary caries). No significant differences in survival (P = 0·53), success (P = 0·49) and ceramic fracture rates (P = 0·57) were detected. The combination of a pronounced anatomical core design and a modified firing of the veneering porcelain for the fabrication of zirconia molar crowns resulted in a 3-year survival, success and chipping rate comparable to MCC. PMID:23211063

Rinke, S; Schäfer, S; Lange, K; Gersdorff, N; Roediger, M

2012-12-05

400

[Bacteriological findings for endodontical and apical molar dental diseases in the horse].  

PubMed

In most cases the diagnosis of any molar dental disease in horses is made at an advanced stage, so that permanent restoration of the diseased teeth is not feasible. Complications such as bacteraemia and septicaemia due to infections as a result of dentogenous sinusitis and following dentosurgical procedures have been described in human medicine and in veterinary medicine. Twenty patients were available for examination from the Clinic for Horses of the School of Veterinary Medicine Hannover with molar dental disease in upper or lower jaw. As a result of this disease the infected tooth had to be removed surgically. The aim of this study was to determine the presence of and to identify microbes in 20 patients. Swab samples were taken from infected pulpa, from dental abscesses and from involved nasal sinuses. The samples were examined microbiologically and tested for aerobes and anaerobes at the same time. Infectious agents were found in 19 of 20 horses. In all, 27 different species of infectious agents were isolated, including both aerobic and anaerobic microbes. Fifteen patients (75%) showed a mixed flora. Further differentiation indicated a preponderance of the group of gram-negative obligatory anaerobic agents isolated from a total of 17 horses. In all these samples there was a high concentration of infectious agents of these genera, the most common of which were Prevotella spp (n = 16) and Fusobacterium spp. (n = 15). Pre-surgical antibacterial therapy is recommended to reduce the risk of intra- and/or post-surgical bacteraemia and its serious consequences. In light of these microbiological results and considering the high degree of resistance among all anaerobic microbes, all patients in this study were treated with Amoxicillin. PMID:14560441

Bienert, A; Bartmann, C P; Verspohl, J; Deegen, E

2003-09-01

401

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.

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

2013-01-01

402

Evaluation of the Restoration Success of Endodontic Therapy of the Primary Molars  

PubMed Central

Objectives: The aim of this study was to evaluate the clinical and radiographic success rates of pulpotomized primary molar teeth restored with a compomer material with using United States Public Health Service (USPHS) criteria. Methods: In 173 primary molars of 156 child patients, aged within 4–9 years (mean age: 6.1±1.4 years), conventional pulpotomy treatment were performed. The teeth treated using calcium hydroxide, formocresol or ferric sulphate. After pulpotomy procedure, teeth were restored with compomer material. The teeth were evaluated as clinically and radiographically during a period of 12–24 months. Both of success of pulpotomy treatment and also restorative material (compomer material) were evaluated during follow-up period. The data were assessed with chi-square test. Results: At the end of the first year, 45% of initial treated teeth were checked, but only 18% were checked at the end of the second year. The first year success rates in the groups treated with CH, FC, and FS were 87.5%, 95%, and 79%, respectively, and, as the number of controllable patients was lower, the success rates on available teeth were determined to be 88.3% and 80%, respectively, according to the materials at the end of the second year. Restorations having been made, they were analyzed in accordance with USPHS criteria. Conclusions: At the end of the first year, 67.5% of compomer restorations were detected to be original and healthy and at the end of the second year, 57% were deemed healthy. No statistically significant relationships were found between marginal adaptation, secondary caries and pulpotomy success (chi-square test, P>.05). Among the three groups, there is no significant difference in terms of success. The least successful age group was defined as 4–6 years.

Kirzioglu, Zuhal; Gungor, Ozge Erken; Ciftci, Z. Zahit

2011-01-01

403

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

404

Mandibular first molars with disto-lingual roots: review and clinical management.  

PubMed

The purpose of this review was (i) to conduct a literature review on the prevalence and morphologic classification of mandibular first molars with disto-lingual (DL) roots, and (ii) to discuss the clinical approach to diagnosis and root canal treatment of these teeth. A search was carried out on electronic (MEDLINE, PubMed and Cochrane) and hand databases, which covered all publications from 1970 to December 2011. Two reviewers independently assessed the studies and recorded type of study, origin and sample sizes, number of teeth with three roots and type of root canal configuration. Forty-five studies were identified with a total of 19,056 mandibular first molar teeth. The frequency of DL roots was 14.4% and was associated with certain ethnic populations. The most common canal configuration of mesial and distal roots was Vertucci types IV and I, respectively. No significant differences were observed in the prevalence of DL roots according to gender. Variable results related to side were observed as well as a trend in bilateral occurrence. The root length of the DL roots was in general shorter than that of the disto-buccal roots (DB). Most DL roots had a greater angle of curvature and a smaller radius of curvature in a bucco-lingual orientation. The best methods to identify DL roots are a 25° mesial parallax periapical radiograph or cone-beam computed tomography (CBCT). A trapezoidal shape access cavity is desirable to locate the orifice of the DL canal. Clinicians should be aware of the variable furcation levels during coronal pre-flaring or post-space preparation to avoid furcal/strip perforations and a weakening of DL roots. PMID:22681628

Abella, F; Patel, S; Durán-Sindreu, F; Mercadé, M; Roig, M

2012-06-11

405

Comparison of dental measurement systems for taxonomic assignment of first molars.  

PubMed

Morphometrics of the molar crown is based traditionally on diameter measurements but is nowadays more often based on 2D image analysis of crown outlines. An alternative approach involves measurements at the level of the cervical line. We compare the information content of the two options in a three-dimensional (3D) digital sample of lower and upper first molars (M(1) and M(1) ) of modern human and Neanderthal teeth. The cervical outline for each tooth was created by digitizing the cervical line and then sectioning the tooth with a best fit plane. The crown outline was projected onto this same plane. The curves were analyzed by direct extraction of diameters, diagonals, and area and also by principal component analysis either of the residuals obtained by regressing out these measurements from the radii (shape information) or directly by the radii (size and shape information). For M(1) , the crown and cervical outline radii allow us to discriminate between Neanderthals and modern humans with 90% and 95% accuracy, respectively. Fairly good discrimination between the groups (80-82.5%) was also obtained using cervical measurements. With respect to M(1) , general overlap of the two groups was obtained by both crown and cervical measurements; however, the two taxa were differentiable by crown outline residuals (90-97%). Accordingly, while crown diameters or crown radii should be used for taxonomic analysis of unworn or slightly worn M(1) s, the crown outline, after regressing out size information, could be promising for taxonomic assignment of lower M1s. PMID:21302262

Benazzi, Stefano; Coquerelle, Michael; Fiorenza, Luca; Bookstein, Fred; Katina, Stanislav; Kullmer, Ottmar

2010-11-10

406

[The method of esthetic crown restoration with composite resin jacket crown in primary molars].  

PubMed

The term "esthetics" has recently been also used in the dental field, and a field called esthetic dentistry is increasingly being noted. The number of not only adult but also pediatric patients who visit for treatment aiming at esthetic recovery is being increased. Inpedodontics, composite resin of the coronal color is generally used in the restoration of deciduous incisors. However, the method using metal crowns for the deciduous teeth is used for the deciduous molars at present. We applied a composite resin jacket crown to the deciduous molar in a way similar to that of esthetic crown restoration for the anterior teeth. The surgical procedure before crown preparation varied slightly according to the presence or absence of pulpal treatment of vital teeth and with non-vital teeth, but the application was performed as follows: 1) Desensitization of pulp, pulpal treatment and core construction. 2) Preparation of crown. 3) Selection, trial set and occlusal equilibration of a metal crown for the deciduous tooth. 4) Precision impression with a silicone impression material. 5) Removal of the metal crown for the deciduous tooth from the impression material. 6) Making of an under-cut to the abutment tooth on the buccal lingual side. 7) Filling of the impression with chemical polymerization resin. 8) Application of pressure in the oral cavity. 9) Adjustment of edge and crown forms. Thus, the preparation method for the composite resin jacket crown was relatively simple. Since this surgery, the patient has been followed up for 1 year and 6 months, and no specifically troublesome points have been observed clinically. The patient and her parents are satisfied with the results.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2134806

Doi, K; Shibui, N; Suda, M; Uehara, M; Karibe, H; Kondou, K

1990-10-01

407

A Physiological Permeability Study of Third Molar Dentine with Odontoblasts Preserved and Odontoblasts Free Preparations  

PubMed Central

Introduction Dentine a viable biological tissue forms an intimately related complex with the odontoblasts. Much has been question of the barrier properties of dentine within teeth and between teeth.. In human adults the odontoblasts are fully differentiated post-mitotic cells, which send its cytoplasmic processes into the dentinal tubules, yet various studies in the physic of fluid flow in dentine takes little recognition of its presence. The permeability of dentine has been implicated in a possible hydrodynamic mechanism by which rapid fluid movement in the tubules is thought to depolarise the nerve endings. Objective The innovative aim from this pilot investigation is to contribute to the understanding of the influence of odontoblasts on the permeability of human dentine. Methodology This study describes the permeability in odontoblast preserved and odontoblast free preparations in vitro i.e. comparing fluid flow across dentine in human third molars. The pulp tissues were removed from human third molars leaving the odontoblasts attached to the walls of the chamber. The specimens were then either fixed chemically (odontoblast-preserved specimens) or immersed in NaOH (odontoblast free specimens). Occlusal dentine was exposed by removing the enamel. The exposed dentine was placed in contact with water and the ingress of water into the pulp chamber was observed with a binocular microscope. A microlitre syringe was used to measure the volume of water accumulated at time intervals of several hours for up to 70 hours or more. Results The results showed that spontaneous flow continued in both preparations until equilibrium was reached. The relative final volumes were greater in the odontoblast free preparations than in the odontoblast preserved. Conclusion Water movement through odontoblast free dentine was believed to be driven by capillarity and through odontoblast preserved dentine by capillarity and osmotic pressure.

Ghazali, Farid Che

2000-01-01

408

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

2012-03-30

409

Reproducibility of mandibular third molar assessment comparing two cone beam CT units in a matched pairs design.  

PubMed

The aim of this study was to evaluate the reproducibility of the third molar assessment, comparing five observers and two cone beam CT (CBCT) units. 28 patients, each with two impacted mandibular third molars, were included. Each patient was randomly examined with a Scanora(®) 3D (Soredex, Helsinki, Finland) CBCT unit in one mandibular third molar region and with a Cranex(®) 3D (Soredex) CBCT unit in the other region. Five observers with varying CBCT experience assessed all third molars and recorded the following variables: number and morphology of the roots, relation to the mandibular canal in two directions, shape of the canal and whether there was a direct contact between the roots of the molar and the mandibular canal. The radiographic assessments were compared pairwise among all observers for all variables. Wilcoxon's signed-rank test was used to test the differences in observer accordance percentages among the recorded variables in the images from the two units, and kappa statistics expressed interobserver reproducibility. The mean percentages for observer accordance ranged from 65.4 to 92.9 for Scanora 3D and 60.3 to 94.8 for Cranex 3D. There was no significant difference between the observer accordance in the two CBCT units (p?>?0.05), except for assessing root flex in the mesiodistal direction, for which the observer accordance was higher for Scanora 3D (p?molar assessment. Observer variation existed, and experienced radiologists demonstrated the highest interobserver reproducibility for canal-related variables. PMID:24052253

Matzen, L H; Hintze, H; Spin-Neto, R; Wenzel, A

2013-09-19

410

[Dependence of caries protective effect of fluoride varnishes applications on first permanent molars in schoolchildren on the intensity of caries of temporary teeth].  

PubMed

There are four-year clinical research results of the efficacy of the varnishes with different fluoride compounds on first permanent molars in young schoolchildren depending on the lesion of caries of temporary molars. It was determined that for children, whose molars were healthy during the basic examination, the highest caries protective effect was achieved with the help of varnish, containing CaF(2) (the reduction of increase of the intensity of caries of permanent molars formed 59.7%), and for children with initial high lesion of caries of permanent molars the best caries preventive effect was achieved with the varnish "Bifluorid 12®" (the reduction of increase of the intensity of caries of permanent molars formed 52.5%). PMID:22433648

Terekhova, T N; Borutta, A; Shakovets, N V; Klenovskaia, M I; Minchenia, O V

2011-01-01

411

Molar volume, thermal expansivity and isothermal compressibility of trans-decahydronaphthalene up to 200MPa and 446K  

NASA Astrophysics Data System (ADS)

The molar volume isotherms of trans-decahydronaphthalene (C10H18) between 293 and 446 K and at pressures from 10 to 200 MPa have been determined. A modified Tait equation of state is used to fit each experimental molar volume isotherm with a maximum average deviation of 0.029%. The thermal expansivity (cubic expansion coefficient) ? and isothermal compressibility ? were determined by fitting the slopes of the isobaric curves and isotherms, respectively. The coefficients in the equation Vm = C1+C2T+C3T2-C4p-C5pT have been fitted with an average deviation of 1.03%.

Zhu, Hu-Gang; Liu, Zhi-Hua; Tian, Yi-Ling; Xue, Yuan; Yin, Liang

2005-12-01

412

Effect of age, impaction types and operative time on inflammatory tissue reactions following lower third molar surgery  

Microsoft Academic Search

Background  Postoperative mobidity following third molar surgery is affected by a number of factors. The study of these factors is essential\\u000a for effective planning and limitation of morbidity. The aim of this study was to determine the effect of age, type of impaction\\u000a and operative time on immediate postoperative tissue reactions following mandibular third molar surgery.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Consecutive patients with impacted mandibular

Seidu A Bello; Wasiu L Adeyemo; Babatunde O Bamgbose; Emeka V Obi; Ademola A Adeyinka

2011-01-01

413

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.

de Paula, Adrianne Freire; Brito-Junior, Manoel; Quintino, Alex Carvalho; Camilo, Carla Cristina; Cruz-Filho, Antonio Miranda; Sousa-Neto, Manoel Damiao

2013-01-01

414

Excess molar enthalpies for binary mixtures related to supercritical antisolvent precipitation: Carbon dioxide + N-methyl-2-pyrrolidone  

Microsoft Academic Search

An isothermal high-pressure flow calorimeter has been used to measure excess molar enthalpies (HmE) for mixtures of supercritical CO2 and N-methyl-2-pyrrolidone (NMP) under conditions of temperature and pressure typically used in supercritical CO2 antisolvent precipitation (SAS): 313.15 and 338.15K and 9.48, 15.00 and 20.00MPa. Mixtures showed exothermic mixing; excess molar enthalpies exhibited a minimum in the CO2-rich region. The effects

María J. Dávila; Albertina Cabañas; Concepción Pando

2007-01-01

415

Excess molar volumes, viscosity, refractive index, and Gibbs energy of activation of binary biodiesel + benzene, and biodiesel + toluene mixtures at 298.15 and 303.15 K  

Microsoft Academic Search

Excess molar volumes (V\\u000a E), viscosities, refractive index, and Gibbs energies were evaluated for binary biodiesel + benzene and toluene mixtures at\\u000a 298.15 and 303.15 K. The excess molar volumes V\\u000a E were determined from density, while the excess Gibbs free energy of activation G*E was calculated from viscosity deviation ??. The excess molar volume (V\\u000a E), viscosity deviation (??),

Ufuk Sancar Vural; Fatih Durmaz; Ozcan Kocyigit; Hasan Kocyigit; V. Muradoglu; Beril Akin

2008-01-01

416

Analysis of a force system for upper molar distalization using a trans-palatal arch and mini-implant: a finite element analysis study.  

PubMed

The purpose of this study was to analyse distal movements of molars in a force system using a trans-palatal arch (TPA), fixed to the maxillary first molar, and mini-implants placed at the palatal midline, considering the diagnostic standard for placement site in association with variation in upper molar locations, using finite element (FE) analysis. Three-dimensional FE models, divided by the differing direction of traction force, mesiodistal locations of the left and right molars, and the lateral location of the mini-implant were constructed. (1) When a traction force was fixed from the height of alveolar crest to the mini-implant placed at the middle of palate, the molars underwent bodily movement. (2) When the location of the mini-implant was moved to the left of the midline, the amount of distal movement of the left molar increased. When the mesiodistal locations of the left and right molars differed, the amount of distal movement of the molar located mesially was larger than that of the contralateral molar, even when the mini-implant was located on the midline. PMID:22952153

Ueno, Satoshi; Motoyoshi, Mitsuru; Mayahara, Kotoe; Saito, Yoko; Akiyama, Yuko; Son, Seil; Shimizu, Noriyoshi

2012-09-04

417

Soft tissue, skeletal and dentoalveolar changes following conventional anchorage molar distalization therapy in class II Non-growing subjects: a multicentric retrospective study  

Microsoft Academic Search

ObjectivesThe purpose of this retrospective prolective study is to evaluate soft tissue, dentoalveolar and skeletal vertical changes following conventional anchorage molar distalization therapy in adult patients.

Mattia Fontana; Mauro Cozzani; Alberto Caprioglio

418

Abnormal Fossil Upper Molar of Pongo from Thailand: Quaternary Climatic Changes in Southeast Asia as a Possible Cause  

Microsoft Academic Search

We interpret an unusual left M3attributed to Pongo from the Late Middle Pleistocene of Thailand to be an abnormal tooth rather than a supernumerary molar. Its peculiar morphology cannot be related to classical known causes that affect the dental germ: Gemination, schizodontia, synodontia. The ontogenic mechanism that might have led to the morphology of the tooth perhaps reflects stress related

Christelle Tougard; Stéphane Ducrocq

1999-01-01

419

Comparative odontometrical analysis of the first lower molar in Microtus (Terricola) multiplex (Arvicolinae, Rodentia) from western Alps  

Microsoft Academic Search

The morphology of the first lower molar (M1) of Microtus (Terricola) multiplex (Fatio, 1905) was compared amongst 15 populations from the Alps (Switzerland, Italy, France). M. multiplex orientalis from Trentino Alto Adige is close to the nominative subspecies M. multiplex multiplex from Ticino characterised by a great size, a not tilted pitymyan rhombus and an important development of the anterior

Patrick Brunet-Lecomte; Armando Nappi; Sophie Montuire

2010-01-01

420

Effect of mechanical removal of the pulp upon the retention of odontoblasts around the pulp chamber of human third molars  

Microsoft Academic Search

The pulp chambers of 11 freshly extracted human third molars were exposed by cutting off the roots apical to the cervical margin and the pulps were either removed with forceps and discarded or left in situ. The teeth were fixed, demineralized, divided longitudinally, embedded in resin and 2-?m sections stained with toluidine blue were examined by light microscopy. In pulp-removed

S. Chadha; M. A. Bishop

1996-01-01

421

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

422

MOLAR CONCENTRATION ON K2SO4 AND SOIL PH ESTIMATION OF EXTRACTABLE C WITH CHLOROFORM FUMIGATION-EXTRACTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Methods of determining soil microbial biomass need to be reliable and produce consistent results across soils with a wide range of properties. We investigated the effect of extractant molarity (distilled water and 0.001, 0.01, 0.1, and 0.5 M K2SO4) on the flush of C (i.e., the difference between fum...

423

Cephalometric Changes followingSimultaneous First and Second Maxillary Molar DistalizationUsing a Non-Compliance Intraoral Appliance  

Microsoft Academic Search

Aim: The aim of this prospective study was to evaluate the dentoalveolar, skeletal and soft tissue changes induced by a modified minimal-compliance intraoral appliance following the simultaneous distalization of first and second maxillary molars. Subjects and Methods: The study sample consisted of 14 patients with a mean age of 13.4 years treated by one clinician. In all cases a bilateral

Moschos A. Papadopoulos; Anestis Mavropoulos; Andreas Karamouzos

2004-01-01

424

Molar Tooth Sign in Fetal Brain Magnetic Resonance Imaging Leading to the Prenatal Diagnosis of Joubert Syndrome and Related Disorders  

Microsoft Academic Search

Joubert syndrome is a rare autosomal recessive disorder characterized by ataxia, developmental delay, and oculomotor and respiratory abnormalities in relation to cerebellar vermian and midbrain dysgenesis. The midbrain dysgenesis is responsible for the molar tooth sign on axial magnetic resonance imaging (MRI). This classic hallmark of Joubert syndrome has been identified in other disorders sharing overlapping clinical and radiologic features

Joel Fluss; Susan Blaser; David Chitayat; Hani Akoury; Phyllis Glanc; Martin Skidmore; Charles Raybaud

2006-01-01

425

Excess molar volumes for CO(sub 2)-CH(sub 4)-N(sub 2) mixtures.  

National Technical Information Service (NTIS)

Vibrating-tube densimetry experiments are being performed to determine the excess molar volumes of single-phase CO(sub 2)-CH(sub 4)-N(sub 2) gas mixtures at pressures as high as 3500 bars and temperatures up to 500(degrees)C. In our initial experiments, w...

J. C. Seitz J. G. Blencoe D. B. Joyce R. J. Bodnar

1992-01-01

426

Influence of molar ratios of precursor, solvent and water on physical properties of citric acid catalyzed TEOS silica aerogels  

Microsoft Academic Search

The experimental results on the influence of molar ratios of precursor, solvent and water on the physical properties of TEOS silica aerogels are reported. The aerogels have been prepared by hydrolysis and polycondensation of tetraethoxysilane (TEOS) using citric acid as a new catalyst followed by supercritical drying in an autoclave. In order to identify the optimal condition for producing the

P. B. Wagh; A. Venkateswara Rao; D. Haranath

1998-01-01

427

Dental age estimation utilizing third molar development: A review of principles, methods, and population studies used in the United States  

Microsoft Academic Search

When an individual reaches the age of legal majority, their treatment within the criminal and civil legal systems is changed dramatically in the United States. Forensic odontologists are often asked to assist government agencies in estimating the ages of persons who may or may not have reached that legally important age. The third molars are the only teeth useful as

James M. Lewis; David R. Senn

2010-01-01

428

Periodontal healing following orthodontic movement of rat molars with intact versus damaged periodontia towards a bony defect  

Microsoft Academic Search

SUMMARY The aim of this research was to determine whether orthodontic tooth movement infl uences periodontal healing. In 16 male Wistar rats, 12 week of age, a bony defect was created mesial to both maxillary fi rst molars, not including the attachment apparatus (group 1), and in 15 animals, the defect included the periodontal ligament (group 2). In both groups,

Carlos E. Nemcovsky; Merav Sasson; Leah Beny; Miron Weinreb; Alexander D. Vardimon

429

Flare-up Rate in Molars with Periapical Radiolucency in One-Visit vs Two-Visit Endodontic Treatment.  

PubMed

Purpose: The objective of this study was to compare postobturation flare-ups following single and two-visit endodontic treatment of molar teeth with periapical radiolucency. Materials and methods: A total of 100 patients with asymptomatic molar teeth with periapical radiolucency were selected. They were randomly allocated into two groups. Fifty patients received complete endodontic treatment in one-visit. Fifty patients received treatment by debridement and instrumentation at the first visit followed by obturation at the second visit. Results: 10% of patients had flare-ups in the single visit group and 8% of patients had flare-ups in the two-visit group. Number of visits did not affect the success of endodontic treatment (p > 0.05). Age, gender and tooth type had no effects on the occurrence of flare-ups regardless the number of visits (p > 0.05). Conclusion: One-visit endodontic treatment was as successful as two-visit endodontic treatment as evaluated by rate of flareups in asymptomatic molar teeth with periapical radiolucency. Keywords: Chronic periapical periodontitis, Endodontic flare-up, Necrotic teeth, Root canal treatment. How to cite this article: Akbar I, Iqbal A, Al-Omiri MK. Flare-up Rate in Molars with Periapical Radiolucency in One-Visit vs Two- Visit Endodontic Treatment. J Contemp Dent Pract 2013; 14(3):414-418. Source of support: Nil Conflict of interest: None declared. PMID:24171982

Kishore, D Trinath; Bandiwadekar, Tushar; Padma, R; Debunath, Surangama; Gp, Profulla; Reddy, Ajay

2013-05-01

430

Morphometry, scanning electron microscopy and x-ray spectral microanalysis of protostylid pits on human lower third molars  

Microsoft Academic Search

Protostylid pits on 50 lower third molars were studied. The depth and width of the pits, the thickness of the enamel at the pit bottom and the concavity of the dentino-enamel junction under the pit were measured by light microscopy. The pit content was examined by scanning electron microscopy and X-ray spectral microanalysis. The results show that the morphometric variables

Dominik Gašperši?

1996-01-01

431

Maxillary molar distalization or mandibular enhancement: A cephalometric comparison of comprehensive orthodontic treatment including the pendulum and the Herbst appliances  

Microsoft Academic Search

Several methods of Class II treatment that do not rely on significant patient compliance have become popular during the last decade, including several versions of the Herbst appliance and the pendulum or Pendex molar-distalization appliances. Yet, these 2 general approaches theoretically have opposite treatment effects, one presumably enhancing mandibular growth, and the other moving the maxillary teeth posteriorly. This study

Donald R. Burkhardt; James A. McNamara; Tiziano Baccetti

2003-01-01

432

Fixed lingual arch appliance for compliance-free unilateral molar distalization in the mandible. Three case studies.  

PubMed

An asymmetrically activated lingual arch appliance enables rapid, unilateral molar distalization in the mandible without active patient compliance. Using the segmented arch technique, the biomechanics involve only the tooth moved, in accordance with the 2-tooth concept, with a large, multi-rooted tooth segment acting as an anchoring unit. The anchorage system requires no maxillary involvement. PMID:11126019

Kinzinger, G; Gross, U; Diedrich, P

2000-01-01

433

Electrical Insulating and Heat-Resistive Properties of PDMS-TEOS Hybrid with Different Molar Ratio of TEOS to PDMS  

Microsoft Academic Search

The hybrids prepared from polydimethylsiloxane (PDMS) and tetraethoxysilane (TEOS) have been well known to be rubbery hybrid materials. In this report, the authors have investigated the electrical insulating and heat resistive properties of the hybrids by changing the molar ratio of TEOS to PDMS. The electrical insulating properties are evaluated by volume resistivity and AC breakdown strength at room temperature.

Makoto Sugiura; Fumitoshi Imasato; Atsushi Ohno; Yusuke Aoki; Shuhei Nakamura; Tetsushi Okamoto; Takuya Shindou

2007-01-01

434

Light and electron microscopic analysis of the somata and parent axons innervating the rat upper molar and lower incisor pulp  

Microsoft Academic Search

The morphology of intradental nerve fibers of permanent teeth and of continuously growing rodent incisors has been studied in detail but little information is available on the parent axons that give rise to these fibers. Here we examined the axons and somata of trigeminal neurons that innervate the rat upper molar and lower incisor pulp using tracing with horseradish peroxidase

S. K. Paik; K. P. Park; S. K. Lee; S. K. Ma; Y. S. Cho; Y. K. Kim; I. J. Rhyu; D. K. Ahn; A. Yoshida; Y. C. Bae

2009-01-01

435

A Review on Prediction Methods for Molar Enthalpies of Vaporization of Hydrocarbons: The ELBA Method as the Best Answer  

NASA Astrophysics Data System (ADS)

A review on prediction methods for molar enthalpies of vaporization at T = 298.15 K of hydrocarbons is presented. A new method is proposed and compared with six of the most common used ones from the literature. This new method, the extended Laidler bond additivity (ELBA), was applied to the prediction of standard molar enthalpies of vaporization of hydrocarbons (alkanes, alkenes, alkynes, polyenes, poly-ynes, cycloalkanes, cycloalkenes, benzene compounds, biphenyl compounds, and polyphenyl compounds) at T = 298.15 K. A total of 260 experimental standard molar enthalpies of vaporization at T = 298.15 K were used for the parameters optimization. Comparison between the experimental values and those calculated using ELBA led to an average absolute difference of 0.35 kJ mol-1, corresponding to an average relative error of 0.92%. In addition, this new method proves to be better than the ones used for comparison with an independent set of 83 experimental standard molar enthalpies of vaporization at T = 298.15 K.

Santos, Rui C.; Leal, Joa~o. P.

2012-12-01

436

Cytomegalovirus induces stage-dependent enamel defects and misexpression of amelogenin, enamelin and dentin sialophosphoprotein in developing mouse molars.  

PubMed

Of the approximately 8,400 children born each year in the US with cytomegalovirus (CMV)-induced birth defects, more than one third exhibit hypoplasia and hypocalcification of tooth enamel. Our prior studies indicated that CMV severely delayed, but did not completely interrupt, early mouse mandibular first molar morphogenesis in vitro. The aim of the present study was to examine the effects of CMV infection on progressive tooth differentiation and amelogenesis. Since initial CMV infection in human fetuses can occur at different developmental times, we varied the stage of initial viral infection (that is, Cap stage, Early Bell stage and Bell stage), as well as the duration of infection. CMV infection of embryonic mouse mandibular first molars in vitro induces tooth dysmorphogenesis and enamel defects in a developmental stage- and duration-dependent manner. Cap stage- and Early Bell stage-infected molars exhibit enamel agenesis and Bell stage-infected molars exhibit enamel hypoplasia. This viral-induced pathology is coincident with stage-dependent changes in Amelx, Enam and Dspp gene expression, distribution of amelogenin, enamelin and DSP proteins, cell proliferation localization and dedifferentiation of secretory ameloblasts. Importantly, our data indicate that specific levels of Amelx and Dspp gene expression define whether mouse CMV induces enamel agenesis or hypoplasia. PMID:20484882

Jaskoll, Tina; Abichaker, George; Htet, Khine; Bringas, Pablo; Morita, Scott; Sedghizadeh, Parish P; Melnick, Michael

2010-05-18

437

The relation of pericoronal third molar follicle dimension and bcl-2/ki-67 expression: An immunohistochemical study  

PubMed Central

Background: Most common impacted teeth are the mandibular third molars and decision about extraction of them is usually controversial. The presence of pericoronal pathologic changes is an acceptable reason for removal of impacted teeth. Differences in the proliferation rate and apoptosis of odontogenic epithelial cells may influence on the formation of odontogenic epithelial lesions. Therefore, the aim of the present study is to evaluate the immunohistochemical expression of the bcl-2 apoptosis-inhibiting protein and the cell-cycle-related ki-67 antigen in pericoronal follicle of impacted third molars with ?2.5 mm and <2.5 mm radiolucency. Materials and Methods: This was a cross-sectional study that 20 follicles with <2.5 mm radiolucency and 20 follicles with ?2.5 mm radiolucency were selected by a professional radiologist in digital panoramic radiographs and then referred to a surgeon. Formalin fixed paraffin-embedded tissues were immunohistochemical analyzed for immunoreactivity of bcl-2 protein and ki-67 antigen. The data was analyzed using logistic regression, Spearman correlation coefficient and t-test and Mann-Whitney. P<0.05 was considered significant. Results: The findings showed correlation between size of the third molar's follicles and expression of bcl-2 protein (P < 0.001, r = 0.556) but there was no correlation between size of third molar's follicles and staining with ki-67 antigen (P = 0.546, r = 0.098). The follicles with radiolucency ?2.5 mm showed increased immunoreactivity for bcl-2 protein. Conclusion: The results of study suggest that impacted third molars with radiolucency ?2.5 mm may be associated with deregulation of cell death, indicated with increased expression of the anti- apoptotic protein bcl-2, while cell proliferation (ki-67) does not seem to play a significant role.

Razavi, Seyed Mohammad; Hasheminia, Daryush; Mehdizade, Mojde; Movahedian, Bijan; Keshani, Forouz

2012-01-01

438

Corneal Stromal Cell Growth on Gelatin/Chondroitin Sulfate Scaffolds Modified at Different NHS/EDC Molar Ratios  

PubMed Central

A nanoscale modification strategy that can incorporate chondroitin sulfate (CS) into the cross-linked porous gelatin materials has previously been proposed to give superior performance for designed corneal keratocyte scaffolds. The purpose of this work was to further investigate the influence of carbodiimide chemistry on the characteristics and biofunctionalities of gelatin/CS scaffolds treated with varying N-hydroxysuccinimide (NHS)/1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) molar ratios (0–1) at a constant EDC concentration of 10 mM. Results of Fourier transform infrared spectroscopy and dimethylmethylene blue assays consistently indicated that when the NHS to EDC molar ratio exceeds a critical level (i.e., 0.5), the efficiency of carbodiimide-mediated biomaterial modification is significantly reduced. With the optimum NHS/EDC molar ratio of 0.5, chemical treatment could achieve relatively high CS content in the gelatin scaffolds, thereby enhancing the water content, glucose permeation, and fibronectin adsorption. Live/Dead assays and interleukin-6 mRNA expression analyses demonstrated that all the test samples have good cytocompatibility without causing toxicity and inflammation. In the molar ratio range of NHS to EDC from 0 to 0.5, the cell adhesion ratio and proliferation activity on the chemically modified samples significantly increased, which is attributed to the increasing CS content. Additionally, the materials with highest CS content (0.143 ± 0.007 nmol/10 mg scaffold) showed the greatest stimulatory effect on the biosynthetic activity of cultivated keratocytes. These findings suggest that a positive correlation is noticed between the NHS to EDC molar ratio and the CS content in the biopolymer matrices, thereby greatly affecting the corneal stromal cell growth.

Lai, Jui-Yang

2013-01-01

439

Effects of the molar mass of the matrix on electrical properties, structure and morphology of plasticized PANI PMMA blends  

NASA Astrophysics Data System (ADS)

The effects of the molar mass of polymethylmethacrylate (PMMA) on electrical, structural and morphological properties of conductive polyaniline-polymethylmethacrylate blends have been studied. We have plasticized the PMMA matrix by using dioctyl phthalate (DioPh). Three different molar masses of PMMA, 15 000, 120 000 and 350 000 g mol-1, have been used. The x-ray diffraction analysis showed amorphous structure for all our studied PANI-PMMA blend films. The SEM micrographs showed more aggregation with the lowest molar mass of PMMA matrix. The direct current (dc) and alternating current (ac) electrical conductivities have been investigated in the temperature range 20-300 K and frequency range 7-1 × 108 Hz. The results of this study indicate an increase of the conductivity when the molar mass of PMMA decreases. With the lowest molar mass of PMMA (15 000 g mol-1), we obtained the lowest percolation threshold (pc?0.3%). The dc conductivity is governed by Mott's three-dimensional variable range hopping (3D VRH) model; different Mott's parameters have been evaluated. At high frequencies, the ac conductivity follows the power law ?(?,T) = A(T)?s(T,?), which is characteristic for charge transport in disordered materials by hopping or tunnelling processes. The observed decrease in the frequency exponent s with increasing temperature suggests that the correlated barrier hopping (CBH) model best describes the ac conduction mechanism. All our blends are well described by the scaling law ?(?)/?dc = 1+(?/?c)n with n?0.51-0.52.

Gmati, Fethi; Fattoum, Arbi; Bohli, Nadra; Belhadj Mohamed, Abdellatif

2008-03-01

440

The determination of GC-MS relative molar responses of some n-alkanes and their halogenated analogs.  

PubMed

The dependence of relative response factors on the carbon atom number related to naphthalene has been investigated in homologous series by using gas chromatography-mass spectrometry. Relative responses of some straight chain aliphatic n-alkanes and their halogenated derivatives (chlorine, bromine and iodine) were compared in the experiments. Linear correlations were found between the molecular structures; i.e., the carbon atom number and relative molar response in current homologous series. In conclusion, mass spectrometric detection combined with gas chromatography was less sensitive to n-alkanes than to their derivatives containing a chlorine, bromine or iodine atom. After n-alkanes, mass spectrometric responses increase in the order of 1-chloroalkanes, 1-bromoalkanes and 1-iodoalkanes. These results are in accordance with electron ionization cross section data for n-alkyl-derivatives. The relative molar responses of the individual CH(2) groups are between 0.171 and 0.178 in the homologous series. The increments of chlorine, bromine and iodine atoms to the relative molar responses are 0.081, 0.141 and 0.492, respectively. Based on these results, the addivity rule is valid for both halogen atoms and CH(2) groups in the case of mono-substituted n-haloalkanes. The results of this study show a significant departure from the additivity rule in the case of polyhalogenated alkanes and alkenes. However, the relative molar response can be calculated by means of simultaneously measuring other compounds. Further study is needed about how to influence the relative molar responses as a function of various experimental parameters. PMID:22781184

Göröcs, Noémi; Mudri, Dénes; Mátyási, Judit; Balla, József

2012-07-10

441

Guided tissue regeneration demineralized freeze-dried bone allograft: treatment of furcation defects in mandibular molars.  

PubMed

The present study evaluated the effects of combined guided tissue regeneration (GTR) and demineralized freeze-dried bone allograft (DFDBA) therapy on the healing of grade III furcation lesions in mandibular molars of seven periodontitis patients. De novo surgical debridement of furcation roofs by fine diamond bur was introduced. Routine presurgical preparation of teeth and a strict plaque control program were performed for at least six weeks before surgery. A papillary conserved full thickness mucoperiosteal flap was used in all cases. In addition to conventional debridement, odontoplasty was performed on the furcation areas with a diamond bur to eradicate inaccessible fissures or grooves and ensure calculus-free root surfaces. Following debridement, the bony defects were filled with DFDBA and covered with polytetrafluoroethylene (ePTFE) membranes. The flaps were then closed by interproximal sutures coronally positioned through the contact point. The ePTFE membranes were removed 6 to 7 weeks after operation. Clinical parameters such as probing depth (PD), gingival recession (GR), probing attachment level (PAL), tooth mobility (TM), and periapical x-ray were recorded at the baseline and 0, 3, 6, 9, and 12 months after removal of the ePTFE membrane. The results showed a significant increase in the probing attachment level and radiographic evidence of bone fill at the furcation sites. Thus, the addition of fine diamond bur debridement on the furcation in the GTR procedure with DFDBA grafting may be effective in the treatment of grade III furcation involvement. PMID:7549565

Liao, C S; Liu, C M; Wong, M Y; Hou, L T; Chang, W K

1995-07-01

442

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

PubMed

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

2008-11-01

443

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

444

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

445

Activation of Satellite Glial Cells in Rat Trigeminal Ganglion after Upper Molar Extraction  

PubMed Central

The neurons in the trigeminal ganglion (TG) are surrounded by satellite glial cells (SGCs), which passively support the function of the neurons, but little is known about the interactions between SGCs and TG neurons after peripheral nerve injury. To examine the effect of nerve injury on SGCs, we investigated the activation of SGCs after neuronal damage due to the extraction of the upper molars in rats. Three, 7, and 10 days after extraction, animals were fixed and the TG was removed. Cryosections of the ganglia were immunostained with antibodies against glial fibrillary acidic protein (GFAP), a marker of activated SGCs, and ATF3, a marker of damaged neurons. After tooth extraction, the number of ATF3-immunoreactive (IR) neurons enclosed by GFAP-IR SGCs had increased in a time-dependent manner in the maxillary nerve region of the TG. Although ATF3-IR neurons were not detected in the mandibular nerve region, the number of GFAP-IR SGCs increased in both the maxillary and mandibular nerve regions. Our results suggest that peripheral nerve injury affects the activation of TG neurons and the SGCs around the injured neurons. Moreover, our data suggest the existence of a neuronal interaction between maxillary and mandibular neurons via SGC activation.

Gunjigake, Kaori K.; Goto, Tetsuya; Nakao, Kayoko; Kobayashi, Shigeru; Yamaguchi, Kazunori

2009-01-01

446

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

2010-08-19

447

Relationship between cusp size and occlusal wear pattern in Neanderthal and Homo sapiens first maxillary molars.  

PubMed

Tooth wear studies in mammals have highlighted the relationship between wear facets (attritional areas produced during occlusion by the contact between opposing teeth) and physical properties of the ingested food. However, little is known about the influence of tooth morphology on the formation of occlusal wear facets. We analyzed the occlusal wear patterns of first maxillary molars (M(1) s) in Neanderthals, early Homo sapiens, and contemporary modern humans. We applied a virtual method to analyze wear facets on the crown surface of three-dimensional digital models. Absolute and relative wear facet areas are compared with cusp area and cusp height. Although the development of wear facets partially follows the cusp pattern, the results obtained from the between-group comparisons do not reflect the cusp size differences characterizing these groups. In particular, the wear facets developed along the slopes of the most discriminate cusp between Neanderthals and Homo sapiens (hypocone) do not display any significant difference. Moreover, no correlations have been found between cusp size and wear facet areas (with the exception of the modern sample) and between cusp height and wear facet areas. Our results suggest that cusp size is only weakly related to the formation of the occlusal wear facets. Other factors, such as, diet, food processing, environmental abrasiveness, and nondietary habits are probably more important for the development and enlargement of wear facets, corroborating the hypotheses suggested from previous dental wear studies. PMID:21337711

Fiorenza, Luca; Benazzi, Stefano; Viola, Bence; Kullmer, Ottmar; Schrenk, Friedemann

2010-12-31

448

Efficacy of anti-inflammatory drugs in third molar surgery: a randomized clinical trial.  

PubMed

This was a double-blind randomized clinical trial to assess the effect of different pharmacological regimens on the level of prostaglandin E2 (PGE2) in urine and saliva, and to correlate the findings to the clinical course after removal of impacted lower third molars. Eighty patients were randomly divided into four groups: group 1 received placebo; group 2 received preoperative ibuprofen, which was continued for a week; group 3 received intraoperative dexamethasone; and group 4 received preoperative ibuprofen, which was continued for a week, in addition to intraoperative dexamethasone. Saliva and urine samples were taken at scheduled intervals. Patients receiving ibuprofen fared significantly better in most parameters. A single dose of dexamethasone alone had a potent but transient beneficial effect when compared to the results with ibuprofen, which showed significant improvement in both subjective and objective parameters. Use of a single dose of intravenous steroids perioperatively helped reduce untoward sequelae, although to a lesser degree and for a shorter duration than continuous ibuprofen. Combining ibuprofen with perioperative dexamethasone added some benefit in some of the measured parameters, but without a statistically significant advantage over using ibuprofen only. PMID:23535007

Mehra, P; Reebye, U; Nadershah, M; Cottrell, D

2013-03-25

449

Quantification of the effect of conformational restriction on supramolecular effective molarities.  

PubMed

The association constants for a family of 96 closely related zinc porphyrin-pyridine ligand complexes have been measured in two different solvents, toluene and 1,1,2,2-tetrachloroethane (TCE). The zinc porphyrin receptors are equipped with phenol side arms, which can form intramolecular H-bonds with ester or amide side arms on the pyridine ligands. These association constants were used to construct 64 chemical double mutant cycles, which measure the free energy contributions of intramolecular H-bonding interactions to the overall stability of the complexes. Measurement of association constants for the corresponding intermolecular H-bonding interactions allowed determination of the effective molarities (EM) for the intramolecular interactions. Comparison of ligands that feature amide H-bond acceptors and ester H-bonds at identical sites on the ligand framework show that the values of EM are practically identical. Similarly, the values of EM are practically identical in toluene and in TCE. However, comparison of two ligand series that differ by one degree of torsional freedom shows that the values of EM for the flexible ligands are an order of magnitude lower than for the corresponding rigid ligands. This observation holds for a range of different supramolecular architectures with different degrees of receptor-ligand complementarity and suggests that in general the cost of freezing a rotor in supramolecular complexes is of the order of 5 kJ/mol. PMID:23360075

Adams, Harry; Chekmeneva, Elena; Hunter, Christopher A; Misuraca, Maria Cristina; Navarro, Cristina; Turega, Simon M

2013-01-29

450

Importance of molar ratios in selenium-dependent protection against methylmercury toxicity.  

PubMed

The influence of dietary selenium (Se) on mercury (Hg) toxicity was studied in weanling male Long Evans rats. Rats were fed AIN-93G-based low-Se torula yeast diets or diets augmented with sodium selenite to attain adequate- or rich-Se levels (0.1, 1.0 or 15 micromol/kg, respectively) These diets were prepared with no added methylmercury (MeHg) or with moderate- or high-MeHg (0.2, 10 or 60 micromol/kg, respectively). Health and weights were monitored weekly. By the end of the 9-week study, MeHg toxicity had impaired growth of rats fed high-MeHg, low-Se diets by approximately 24% (p < 0.05) compared to the controls. Growth of rats fed high-MeHg, adequate-Se diets was impaired by approximately 8% (p < 0.05) relative to their control group, but rats fed high-MeHg, rich-Se diets did not show any growth impairment. Low-MeHg exposure did not affect rat growth at any dietary Se level. Concentrations of Hg in hair and blood reflected dietary MeHg exposure, but Hg toxicity was more directly related to the Hg to Se ratios. Results support the hypothesis that Hg-dependent sequestration of Se is a primary mechanism of Hg toxicity. Therefore, Hg to Se molar ratios provide a more reliable and comprehensive criteria for evaluating risks associated with MeHg exposure. PMID:17916948

Ralston, Nicholas V C; Blackwell, J Lloyd; Raymond, Laura J

2007-12-01

451

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. Am J Phys Anthropol 152:300-305, 2013. © 2013 Wiley Periodicals, Inc. PMID:23999832

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

2013-09-03

452

Distal movement of premolars to provide posterior abutments for missing molars.  

PubMed

In 24 patients with missing molar teeth in the upper and/or in the lower jaw, 32 premolars were distalized. The mean orthodontic distalizing distance was 9.4 mm (SD 2.6). After distalization all these teeth served as posterior abutments for fixed restorations. The investigation period ranged between 2.5 to 14.1 years, average 9.6 years (SD 3.2). The clinical examination criteria were sensitivity, mobility, probing depth, sulcus bleeding index; the radiologic criteria were root resorption (lateral and apical) marginal bone level and axial position. None of the 32 premolar abutments were lost during investigation period. All the teeth maintained their vitality. The measured probing depths and sulcus bleeding indices were low. Of the teeth tested 40.6% revealed localized lateral root resorption on the pressure side; the average postorthodontic depth of root resorption was 0.7 mm (SD 0.3), and the length 2.3 mm (SD 0.6). The follow-up examination revealed a partial repair of the lateral root lesions. The extent of apical root resorption amounted to 0.9 mm (SD 1.1). The marginal bone level showed a bone loss of 0.5 mm mesially and 0.2 mm distally. The findings confirm that the distalized premolar functioning as a posterior bridge abutment represents a prognostically favorable alternative to an implant. PMID:8638576

Diedrich, P R; Fuhrmann, R A; Wehrbein, H; Erpenstein, H

1996-04-01

453

Indirect pulp therapy in a symptomatic mature molar using calcium enriched mixture cement.  

PubMed

Dental pulp has the ability of repair/regeneration. Indirect pulp therapy (IPT) is recommended for pulp preservation in asymptomatic teeth with extremely deep caries as well as teeth with clinical symptoms of reversible pulpitis. In this case study, we performed IPT with calcium enriched mixture (CEM) cement on a symptomatic permanent molar. After clinical/radiographic examinations the tooth was diagnosed with irreversible pulpitis and associated apical periodontitis. IPT involved partial caries removal, the placement of CEM cement pulp cap and overlying adhesive permanent restoration. At the 1 week follow-up, patient's spontaneous symptoms had resolved. One-year follow-up demonstrated pulp vitality, clinical function, as well as the absence of pain/tenderness to percussion/palpation/cold sensitivity tests; periapical radiograph showed a healing periradicular lesion with newly formed bone, that is normal pulp with normal periodontium. These favorable results indicate that IPT/CEM may be a good treatment option in comparison to endodontic treatment in young patients. IPT of deep-caries lesion is an easier, more practical and valuable treatment plan than complete caries removal. PMID:23349584

Torabzadeh, Hassan; Asgary, Saeed

2013-01-01

454

Indirect pulp therapy in a symptomatic mature molar using calcium enriched mixture cement  

PubMed Central

Dental pulp has the ability of repair/regeneration. Indirect pulp therapy (IPT) is recommended for pulp preservation in asymptomatic teeth with extremely deep caries as well as teeth with clinical symptoms of reversible pulpitis. In this case study, we performed IPT with calcium enriched mixture (CEM) cement on a symptomatic permanent molar. After clinical/radiographic examinations the tooth was diagnosed with irreversible pulpitis and associated apical periodontitis. IPT involved partial caries removal, the placement of CEM cement pulp cap and overlying adhesive permanent restoration. At the 1 week follow-up, patient's spontaneous symptoms had resolved. One-year follow-up demonstrated pulp vitality, clinical function, as well as the absence of pain/tenderness to percussion/palpation/cold sensitivity tests; periapical radiograph showed a healing periradicular lesion with newly formed bone, that is normal pulp with normal periodontium. These favorable results indicate that IPT/CEM may be a good treatment option in comparison to endodontic treatment in young patients. IPT of deep-caries lesion is an easier, more practical and valuable treatment plan than complete caries removal.

Torabzadeh, Hassan; Asgary, Saeed

2013-01-01

455

Extension rates and growth in tooth height of modern human and fossil hominin canines and molars.  

PubMed

The aim of this study was to describe similarities and differences in the way modern and fossil ho