Measurements of Deformations of Teeth and Mandibles due to Occlusal Forces

Abstract

When occlusal or masticatory forces were applied to teeth and mandibles, three dimensional (3-D) displacements of their deformations were measured quantitatively by double-exposure holographic interferometry. The mandibles were extracted from adult dogs. As measuring places, buccal surfaces of the teeth and mandibles were selected. When vertical load was applied to the first retromolar (M1), a tiltlike deformation was observed. By this the tooth was displaced to the buccal direction. Experimental observation of a sagittal section shows that deformations of the tooth are larger than that of the corresponding mandible. When a lateral load acted on M1, the buccal surface of M1 was displaced into the upper direction of the tooth axis from the dental socket. In these experiments, two kinds of tensile forces, 100 gm and 200 gm were applied to M1. When the buccal surface of the mandible in the neighbourhood of M1 was partly scraped, the same surface of the tooth was displaced further to the upper direction of the tooth axis. The mandible in the neighbourhood of M1 was displaced in the same direction. These results show that the periodontal membrane plays the role of a buffer and will be valuable to considerations of deformations of human teeth and periodontal diseases.