Healing of periodontal lesions in monkeys following the guided tissue regeneration procedure. A histological study.

The purpose of the present investigation was to study histologically the healing of periodontal lesions in monkeys during the first 9 weeks following periodontal reconstructive surgery according to the principle of guided tissue regeneration. Horizontal interproximal lesions and through-and-through bifurcation defects were surgically produced in 2 adult monkeys. Following removal of granulation tissue and root planing, notches indicating the level of the reduced bone level were prepared in the root surfaces. Sterile teflon membranes were then adjusted to cover the defects, and the gingival flaps were sutured in a coronally displaced position. Sacrifice of the animals was scheduled to allow for observation periods of 1, 3, 4 and 9 weeks. Evaluation of histological specimens revealed a continuous growth of new connective tissue during a period of 4 weeks. The coronal growth of new tissue did not increase significantly between 4 and 9 weeks. New cementum had formed in the most apical part of one notch after 1 week of healing, and following 3 and 4 weeks, new cementum with inserting periodontal ligament fibers were observed in all notches and to a varying degree, also more coronally on the root surfaces of both interproximal and bifurcation defects. Limited regrowth of alveolar bone was observed in the 9-week specimens. Judged from the course of the blood vessels within the newly formed connective tissue in the defects, the tissue in the central part of the defects had originated from the alveolar bone, whereas the tissue adjacent to the root surfaces seemed to have its origin in the residual periodontal ligament.