Numerical investigation of the mechanical role in the development of mandibular bone density
In addition to the inherent genetic factors, the acquired mechanical environment is believed to be another significant factor that contributes to the changes in bone morphology in response to changes of functional loading. In that regard, this study is aimed to test the hypothesis that the development of bone structure in the mandible is determined by the bone adaptation to mastication. Assuming a daily stress state that maintains the bone strength exists as the attractor stimulus. The change of bone density is then mediated by the external loads that deviate the local bone stimuli away from the attractor stimuli. This bone remodeling algorithm is incoporated into finite element analysis. Three dimensional finite element models consisting of teeth and jaw bone are constructed according to medical images of human mandible. Masticatory loads considered here include the muscle forces during clenching and the mandibular flexure during jaw open and close. The mandible is initially assumed to have an unrealistically low, uniform density distribution. After 1500 days of remodeling, the predicted bone density distribution forms a tubular structure similar to the observations in medical images, where the surface region of mandible turns into denser cortical bone layer and the inner section is filled with lighter cancellous bone. Such bone architecture is known to provide bone the optimum strength to resist bending and torsion during mastication.