Evaluation of the Effects of Cavity-Margin-Angles on Stress Distribution of Indirect Resin Composite Restorations with Finite Element Analysis

This study was performed to investigate the distribution of stress in indirect resin restorations of class II MOD cavities for obtaining the optimum wall angle and also the effect of axiopulpal angle bevel using 3D finite element analysis (FEA).
Material & A three-dimensional model of normal mandibular first molar and three class II cavity models with different wall angles were created. Also, all models were examined with axiopulpal angle bevel. The vertical occlusal force of 100 N was applied. The characteristics of all materials were defined as isotropic and elastic and, with the aid of a linear analysis; the distribution of stress and the maximum stress created in each model were obtained in mega-Pascal scale. T test was used for statistical of data.
The maximum stress in the simulated normal tooth was 24.63 MPa. Distribution of stress indicates the accumulation of pressure in the center and the furcal region of the first molar, as well as the cusps in the occlusal region. In beveled model of 95-degree angle, maximum stress was 24.90 MPa with a decrease of 0.05 maximum stress compared to the non-beveled model. In the cutting angle of 97.5, the maximum stress was 24.85 in the no-bevel model to the maximum stress of 24.80 in the model compared with axiopulpal angle bevel, which showed achieved a decrease of 0.05 in the maximum stress. At the cutting angle of 100, the maximum stress of 25.30 was in the no-beveled model comparing to maximum stress of 25.20 in the model with axiopulpal angle bevel, which showed red action of MPA.
Considering the limitations of such software studies, it seems that according to the results, the best treatment result is at angle of 97.5. Axiopulpal angle bevel reduces the maximum stress in the restoration and reduces the chance of failure