Biomechanical Evaluation of the Mandibular First Molar After Simulated Occlusal Wear Using 3D Finite Element Analysis

PURPOSE ：This study aimed to investigate the biomechanical basis of vertical tooth fracture occurring in the mesial root of the mandibular first molar. METHODS： We used 3D finite elements to analyze the stress distribution and transient displacement of the mandibular first molar after occlusal surface wear and tooth tilt. Based on four degrees of wear within each of the surface wear and tooth tilt groups, eight models were established in addition to the control model. A simulated bite force of 200 N was loaded on the occlusal surface, and nonlinear finite element analysis was used to explore the biomechanical basis of vertical root fracture. RESULTS： When the distal tipping angle of the abrasion plane of the mandibular first molar increased from 5° to 15°, the angle between the instantaneous displacement contours and the long axis of the tooth decreased. Meanwhile, the mesial root was found to suffer the highest stress concentration, and the possibility of longitudinal root fracture was increased. CONCLUSION: By evaluating the biomechanical effect of tooth wear and occlusal loading, we are able to identify some clinical interventions that may prevent vertical tooth fracture.