Biomechanical Studies on Trabeculation of Mandible. Part. 1. Trabecular Pattern around Natural Tooth and Load Transmission of Bite Force.

This study was designed to attest the hypothesis that trabecular patterns of mandible are closely related to the stress distribution or the load transmission pattern. Two-dimensional finite element models of transverse sections at molar and the incisor region of the mandible were prepared for the analysis. Loads ranging from vertically to horizontally were applied at the occlusal surface of the tooth. Stress distribution pattern expressed by the maximum and minimum principal stress vectors was compared with trabeculation patterns of human specimens reported by Masuda (1960).The following results were obtained.1. Stress distribution expressed by principle stress vectors in finite element models had patterns similar to the trabeculation in human mandible specimens.2. According to the frequency of trabecular patterns in human specimens, the trabecular formations in the mandibular molar region were heavily influenced by occlusal forces, particularly vertical forces. In the incisor region, biomechanical factors other than occlusal forces could also contribute to trabecular pattern formation.3. Trabeculae in the mandible were divisible into tensile and compressive trabecular groups.4. According to our results, past main loading condition of the tooth can be estimated with the trabeculation patterns.