Effects of destructive periodontitis, induced by diet, on the mechanical properties of the periodontal ligament of the mandibular first molar in golden hamsters.

To examine progressive changes in the mechanical properties of the periodontal ligament in the hamster mandibular first molar with experimental periodontitis--induced by feeding a high-carbohydrate diet--load-deformation curves obtained by extracting the tooth from its socket in the dissected jaw were analyzed. The maximum shear load, elastic stiffness and failure energy in shear in the experimental groups decreased significantly during the experimental period. On the other hand, significant differences in the maximum deformation were not found between the experimental and the relevant control groups. Radiographic and histological observations showed that the alveolar bone loss and destruction of the periodontal tissues occurred at the cervical region of the tooth in the experimental animals at 8 and 12 weeks after the start of the experiment. It is suggested that the reduction of the mechanical strength of the periodontal ligament in the experimental animals may be due to the alveolar bone loss, destruction of the periodontal tissues at the cervical region--particularly on the lingual aspect--followed by a decrease in the surface area of the ligament. It is also suggested that degenerative changes in the remaining periodontal ligament occurred in hamsters with periodontal disease, causing a reduction in the mechanical strength of the ligament.