Stress Distribution in Root with Different Post and core Systems

Objective: Root fracture is one of the most disturbing problems for dentists. Especially, sometime vertical or horizontal root fracture occurs in the abutment teeth with flared post hole. The aim of this study was to evaluate the influence of three kinds of post system on stress distributions in an abutment tooth had flared post hole by 3-dimensional finite element analysis. Methods: Three types of 3-dimensional finite element models of endodontically treated premolar with flared post hole were made. In each model, posts and cores were built up with composite resin with prefabricated stainless steel post (SSP), composite resin with glass fiber post (GFP), and cast post and core (CPC). In all models, same occlusal force, which were measured with a small 3-dimensional occlusal force meter during chewing beef jerky in vivo, were applied to the center of occlusal surface (lingual direction:24N,distal direction:29N, apical direction:164N). Then Von Mises stress within the root dentin, composite resin around two kinds of prefabricated post and luting agent around the end of CPC were calculated. Results: The magnitude of stress at the root dentin around the end of post for SSP, GFP, and CPC were 12.8 Mpa, 11.1 MPa, and 13.6 MPa, respectively. On the other hand, the magnitude of stress of composite resin around the two kinds of prefabricated post (SSP, GFP) and luting agent around the end of CPC were 36.9 Mpa, 11.7 MPa, and 26.3 MPa, respectively. Conclusion: Within the limitation of this experiment, GFP thought to be most suitable for endodonticall treated teeth with flared post hole, since this model showed lower stress value within the root dentin and composite resin around the end of prefabricated post, which means less possibility of root fracture.