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.

Early orthodontic treatment of unilateral mandibular left lateral incisor–canine transposition: A Case Report

Among dental anomalies, tooth transposition is considered the most difficult to manage clinically. Distal migration of permanent mandibular lateral incisor happens rarely. It can be discovered radiographically in the early mixed dentition & interceptive treatment is often appropriate. If left uncorrected it may erupt ectopically and the results are often unsatisfactory both esthetically and functionally. When transpositions are detected early the positions of the root apices are important in deciding where to move the transposed tooth. This article reports a case of early orthodontic treatment of a rare unilateral mandibular left lateral incisor – canine transposition.