Biomechanical studies on shape effect of hydroxyapatite artificial root upon surrounding jawbone. 
To study the shape effect upon surrounding tissue of artificial dental root made of synthetic hydroxyapatite, this paper deals with the numerical analysis of the artificial root on functioning jawbone with the aid of the finite element method (FEM).  The stress distribution around artificial roots in the shape of a cylinder, a cone, and three types of corrugated cone, including the newly tailored type implanted in the mandibular molar region, was analyzed in the plane strain state.  The numerical results showed that the stress distribution was sensitive to the artificial root shape, and that the stress state was distributed in mitigatory way around the roots of the newly tailored form.  The pattern of osteogenesis in the animal experiment and the finite element analysis (FEA) pattern showed a close correlation.  Osteogenesis was assumed to occur in the weak or moderate stress distribution zone.  The principal stress trajectory pattern in the lamina dura around the tailored artificial root was indicated as being either parallel or normal to the root surface.  From this study, the biomechanical property of the tooth can be identified as a vehicle of mastication forces which disperse stresses moderately and equally upon surrounding tissues.  Also, the periodontal ligament can be identified as a converting system of principal stress trajectories.