Periodontal tissue changes caused by increased occlusal stress in teeth adjacent to extracted molars in rats

Abstract

In order to establish a model for observing the periodontal tissue changes caused by increased occlusal stress in teeth adjacent to an extraction site in rats, we examined the tissue 4, 7, 12, 24 and 48 weeks after the extraction. Examination was carried out macroscopically, with light microscopy and by confocal laser scanning microscopy (LSM). The rats were divided into two groups. In group A, the mandibular left first molars were extracted under anesthesia. The same treatment was done on the animals in group B, and in addition the crown of the mandibular left second molar was removed. In order to carry out LSM observation, the rats were injected subcutaneously with 0.16% calcein solution every day for 10 days before euthanasia. Both groups were fixed perfusively with 10% buffered formalin solution before removal of the mandibles.
There was a daily reduction in the width of the cortical bone and a decrease in the amount of cancellous bone trabeculae. However, the trabeculae increased at 48 weeks after the first molar extraction and removal of the second molar crown. Although it was not easy to observe the trabeculae of the rat alveolar bone with light microscopy, it was possible with LSM. These results suggest that rats may be used as a model for investigating changes in the periodontal tissues caused by increased occlusal stress in teeth adjacent to an extraction site when suitable observation methods are used. Shika Igaku (J Osaka Odontol Soc) 1997 Jun； 60(2)：159-164．