Evaluation of stress in three different fiber posts with two-dimensional finite element analysis.

INTRODUCTION: The primary function of corono-radicular post is to provide retention for the core and to reinforce and to replace the remaining coronal tooth structure. There is considerable controversy regarding optimal choice of the material. An ideal post system should exhibit fracture resistance higher than the average masticatory forces. Finite elemental analysis (FEA) method facilitates precise analysis of the distribution and magnitude of stresses at any point of complex and irregular structures. Thus, this FEA study has been undertaken to evaluate the fracture stress distribution patterns in three fiber posts, viz., carbon, glass fiber, and everStick with an FEA. MATERIALS AND METHODS: The FE stress analysis was performed with the FE software program (CATIA). Three two-dimensional FEA models of central incisor were simulated, and elastic moduli and Poisson's ratio of all the materials were fed to the software. For all the models, a 200 N vertical force was applied on the lingual surface of the tooth at an angle of 45°. Stress concentration and distribution were evaluated and noted down for all the models. To evaluate the stresses within the restored tooth, the modified von Mises failure criterion was used. The equivalent stresses found in the tested models were compared with the tensile strength of the respective materials. Contact stresses in the luting cement-dentin interface were calculated. RESULTS: Finite element method revealed that maximum stress concentration was at the point of stress application. The stress value was highest in carbon fiber post followed by glass fiber post and least stresses found in everStick post. Maximum stress was observed at the labial surfaces of crown. However, the stress values and distribution were more homogenous in everStick post. CONCLUSION: The present findings suggest that everStick post has uniform stress distribution within tooth structure.

Cone Beam Computed Tomography Evaluation of Hand Nickel-Titanium K-Files and Rotary System in Primary Teeth.

PURPOSE: The purpose of this study was to compare canal transportation, centering ability, and removed dentin thickness (RDT) using hand nickel-titanium (NiTi) K-flex files and rotary systems in primary molars and using cone beam computed tomography (CBCT). METHODS: This study was conducted on 20 primary maxillary and 20 primary mandibular molars, which were randomly divided into two groups to be instrumented with hand NiTi K-flex files and a rotary system. Pre- and post-instrumentation slices were taken at three predetermined levels using CBCT to evaluate all the parameters by using Digital Imaging Communications in Medicine (DICOM) software. The results were statistically evaluated. RESULTS: Rotary instruments caused significantly less canal transportation and showed more centering ability than hand NiTi instruments at all levels and in all directions, except at the cervical level in the mesiodistal direction, where the hand group showed significantly superior results. The hand NiTi K-flex files removed significantly more dentin than rotary instrumentation at all levels and in all directions, except at the apical level in the buccodistal direction, where no significant difference between the two groups was observed. CONCLUSION: Rotary files showed less canal transportation, more conservation of tooth structure, and superior centering ability compared to hand nickel-titanium K-flex files.

Assessment of caries status among schoolchildren according to decayed-missing-filled teeth/decayed-extract-filled teeth index, International Caries Detection and Assessment System, and Caries Assessment Spectrum and Treatment criteria.

BACKGROUND: Detection and evaluation of dental caries is of epidemiological importance. Its early detection is important to commence appropriate treatment planning. Cavitated, noncavitated, and initial lesions of dental caries can be detected by various indices. OBJECTIVES: The objective of the study was to assess the caries experience in schoolchildren using decayed-missing-filled teeth (DMFT)/decayed-extracted-filled teeth (deft), International Caries Detection and Assessment System-II (ICDAS-II), and Caries Assessment Spectrum and Treatment (CAST) systems. MATERIALS AND METHODS: An epidemiological survey was carried out among 1550 schoolchildren (37,644 teeth) between the age ranges of 4 and 14 years. American Dental Association type III examination was performed using plane mouth mirrors and community periodontal index probes using DMFT/deft, ICDAS II, and CAST indices. RESULTS: Out of 37,644 teeth examined, 2,718 teeth had shown caries. Caries experience with DMFT/deft index was 5.54%. Highest score of DMFT was observed in deciduous dentition period (59.02%). Overall prevalence of dental caries with ICDAS and CAST system was 6.7% and 6.95%, respectively. The highest percentage of noncavitated lesions (ICDAS - 2.26% and CAST - 3.9%) and greater prevalence of caries among deciduous teeth (ICDAS - 53.2% and CAST - 58.7%) was observed with both ICDAS and CAST systems. CONCLUSION: A high prevalence of noncavitated lesions and less number of sealants and restorations indicates the lack of awareness for prevention and treatment of oral diseases, which suggests a strong need for preventive and operative treatments.

Clinical Evaluation of Conventional Radiography, Radiovisiography, and an Electronic Apex Locator in Determining the Working Length in Primary Teeth.

PURPOSE: This study's purposes were to: (1) compare the accuracy of conventional radiography (CR), radiovisiography (RVG), and the Root ZX mini apex locator (EAL) in determining the working length in primary teeth; and (2) determine the effect of wet/dry conditions on the accuracy of the EAL. METHODS: Twenty-two children (six to 15 years old), with 41 root canals of primary teeth with or without resorption indicated for extraction, were selected. CR and RVG were used to determine the working length, followed by EAL, according to the manufacturer's instructions in both dry and wet fields (saline). Following extraction of the teeth, the actual working length was determined under stereo microscope (2X). The data was tabulated and statistically analyzed using one-way analysis of variance and student's t test. RESULTS: The highest percentage of accurate working length measurements within the acceptable range of ±0.5 mm were for EAL (95.1 percent), followed by RVG (75.6 percent) and CR (75.6 percent). There were no statistically significant differences between the three techniques (P>0.05), and the readings obtained by the apex locator were not affected by resorption or the medium (wet/dry). CONCLUSIONS: The Root ZX mini apex locator showed the most promising results, followed by radiovisiography and conventional radiography.

Prevalence of Malocclusion among 6 to 10 Year old Nalgonda School Children.

BACKGROUND: To evaluate the prevalence of malocclusion among 6 to 10 year old children of Nalgonda District. MATERIALS & METHODS: A total of 3000 children were examined, out of which 2135 children (1009 boys and 1126 girls) who fulfilled the inclusion criteria were included. The selected sample was examined for Class I, Class II, Class III molar relationship, lower anterior crowding, cross bite (anterior and posterior), open bite, and pseudo class III [edge to edge bite] discrepancies after obtaining the written consent from the concerned school authorities. The collected data was tabulated and statistically analysed using chi-square test. RESULTS: Among the selected sample, 648 (30.35%) children had minor tooth alignment discrepancies. Angle's Class I molar relation with and without minor discrepancies was observed in 78.6%, Class II in 13.9%, Class III in 7.8% of the subjects surveyed. Lower anterior crowding in 11.8%, anterior cross bite in 4.5%, posterior cross bite in 3.75%, openbite in 3% and Pseudo class III [edge to edge] in 5.97% was noticed among the studied population. There was no statistical significant difference observed gender wise. CONCLUSION: In the current study, 52% of the studied population had malocclusion with a higher prevalence of Angle's Class I molar relation with lower anterior crowding. How to cite this article: Reddy ER, Manjula M, Sreelakshmi N, Rani ST, Aduri R, Patil BD. Prevalence of Malocclusion among 6 to 10 Year old Nalgonda School Children. J Int Oral Health 2013; 5(6):49-54 .