In the past, many tooth FE (finite element) model have been designed, based on the assumption that mandibular trabecular bones are homogeneous. However, the previous methods have the limited accuracy and applicability due to the high degree of material heterogeneity in the trabecular bone structure. The purpose of the present study was to suggest a microstructural model for tooth and to compare the results of the present model with those of previous models by using finite element analysis. In this study, a micro-FE model of tooth within mandibular trabecular bone is generated and analyzed. The elastic modulus of the periodontal ligament was analyzed by finite element method and compared with that of previous model and experiment model.