There are many different types of periodontal diseases. One such disease causes a defect of alveolar bone that is considered serious. Hence, researchers have examined potential treatments for this type of disease using tissue engineering techniques. Periodontal tissues are exposed to mechanical stress caused by occlusion and mastication, and both the cells and extracellular matrix in these tissues undergo architectural modifications to compensate for the applied stress. Therefore, in this study we analyzed the effect of mechanical tension on the osteogenesis of human dental pulp stem cells (DPSCs). To identify osteogenesis induced by mechanical stress in dental pulp, we examined the effects of tension on DPSCs. We evaluated the effects of mechanical stimuli on the osteogenesis of human dental pulp cells grown on silk scaffolds subjected to 10% strain using a bioreactor. The tension was applied with 0.2 Hz over the course of 5 days and was then continuously applied for 10 more days. We evaluated cell differentiation by RT-PCR, Western blotting and immunohistochemistry. Applying 10% tension to the culture resulted in increases in collagen type I, fibronectin, osteoprotegerin, and bone sialoprotein expression and decreases in a-smooth muscle actin expression. These data suggest that mechanical stimulation promotes osteogenesis in DPSCs.