Evaluation of fracture strength and Analysis of stress distribution using Finite Element Analysis in overflared bovine incisors restored with multi post approach

Abstract

Objectives: The aim of the present study was to evaluate the fracture resistance and stress distribution analysis of overflared bovine endodontically treated central incisors, restored with two geometries of glass fiber posts, using the multi-post approach. Materials and methods: Sixty-eight bovine central incisors were decoronated. The root canals were prepared and obturated. Post spaces were prepared at a length of 10 mm and 1 mm of remaining root canal dentin thickness. The samples were randomly assigned to four groups in terms of fiber post placement. Group 1: two cone-shaped glass fibers; group 2: cone-shaped glass fiber + a braided glass fiber; group 3: two braided glass fibers; group 4: no glass fibers. After core fabrication and thermocycling, the samples underwent a compressive force from the palatal surface at a crosshead speed of 0.5 mm/min and 135º relative to the long axis of the tooth, until fracture occurred. The data were analyzed using one-way ANOVA and post hoc Tukey tests at a significance level of P<0.05. Results: The fracture resistance in groups 3 and 4 were the maximum and minimum, respectively. There was a significant difference between group 4 and the other groups (P<0.001). The difference between the glass fiber groups (1,2,3) was not significant. By the FEA,the greatest stress was observed in the cervical region,regardless of the model. von Mises stress was lower in group 1, than other groups.

Conclusion: Irrespective of the geometry of glass fiber posts, the multi-post approach resulted in a significant increase in the fracture resistance of endodontically treated teeth with overflared root canals. FEA images suggested that the use of fiber post could improved stress distribution in overflared roots canal.