Three-Dimensional Finite Element Analysis Of Ferrule And Various Material Of Post And Core In Anterior Teeth Residual Root

Objectives:This research draws up from biological mechanics angle, utilizes three dimensional finite element models to study the influence of making ferrule or not and various material of post and core to the stress distribution of the anterior teeth residual root. Analyze stress variation in order to discuss the greatest method of the anterior teeth residual root restoration,and provide reference for the clinical work.Methods:An extracted,intact,caries free maxillary central incisor was scanned by screw CT,exported data directly in BMP form. Using Photoshop7.0 software,Matlab6.5 software and Ansys finite element software to establish three dimensional finite element models of a maxillary central incisor restored with post and PFM crown. Groups were assigned according to make ferrule or not and various material of post and core. Models received a 45 degree oblique load at a constant intensity of 100N static loading to the long axis of the tooth at incisal 1/3. The Von Mises stress and the maximum tensile stress within tooth structure were recorded to analyze the influence of making ferrule or not and material of post and core to stress distribution. Results:1. Using screw CT, Matlab software and Ansys finite element software has established three-dimensional finite element models of normal maxillary central incisor and the residual root restored with different methods.2 Whatever the type of post and core material, The stress in the cervical region of the tooth model with 1.5mm ferrule got by crown lengthening is significantly more than the model with no ferrule.3. The stress in the cervical region decreases as the elastic modulus increase. The stress in the interface of post and dentin and dentin at post apex raises following by the elastic modulus of post and core increasing .Conclusions:1. The Finite Element Method is a simple and convenient way in oral biomechanical analysis.2. Crown lengthening just for making ferrule doesn't mean excellent restoration.3. The materials of post-core demonstrate great influence on the quantity and distribution of stress in dentin.The post with higher elastic modulus can release the stress in the cervical region, makes larger stress concentration in the dentin around post and dentin at post apex. The materials with elastic modulus similar to that of dentin do not makes larger stress concentration in the dentin around post and dentin at post apex. The materials with elastic modules similar to that of dentin, may be well fit to post -core restoration.