In this work the mechanical response of tooth supporting structure to the occlusal load was analyzed by means of finite element analysis. The attribution of the cementum-dentine junction (CDJ) and cementum to the stress distribution was investigated. Models of block-shape mandible included a premolar with/without cementum-dentine junction (CDJ) and cementums in the supporting structures were constructed. For each case, a load of 50 N was applied to the crown at a 45-degree angle to the long axis of the tooth. The present finite element analyses indicated that incorporation of CDJ and cementum resulted in decreases in the stress levels. These two tissues are important in absorbing and distributing stress thus they should be considered in analyzing the load transfer characteristics within the tooth supporting structure. In addition, this study proved that it is feasible to simplify the finite element model by employing the modified Young's modulus of PDL to realize the function of CDJ. Moreover, an attempt to correlate the results of the current study with the dental implant designing was made.