Stress distribution on various degrees of curved roots with different post systems by finite element analysis

Abstract

To investigate and compare stress distribution in various degrees of curved roots with different post systems by finite element analysis (FEA). 16 3D-FEA models were created and adapted by using computer software based on external anatomy of mandibular second premolar. Two directions of load were applied. The results were expressed as the distribution of tensile and compressive stresses. The stress distribution showed that the degrees of root curvature in this study (15º, 30º and 45º) had a little effect on the stress distribution pattern except when the direction of force was the same as the root curvature. The degrees of root curvature affected both the stress distribution pattern and magnitude in the latter situation. When the modulus of elasticity of post and core materials was closed to the root dentin, the highest tensile stress concentration was found only on the external root surface. In contrast, when the modulus of elasticity of post and core materials was higher than those of root dentin, the highest tensile stress concentration was found both on the post-dentin interface and at post apex. This effect of metal post restoration increased when direction of force was the same as root curvature. Vertical or horizontal root fracture might occur in this condition. This study suggested that the suitable restoration in endodontically treated premolar with limited loss of tooth structure was resin composite that was filled in the coronal third of the root canal. However, when the post and core were indicated, the glass-fiber post and resin composite core were the materials of choice for restoration.