Periodontal healing after replantation and autotransplantation of incisors in monkeys.

The effect of injury to the cemental or alveolar part of the periodontal ligament upon periodontal healing after replantation and autotransplantation of teeth was studied in green Vervet monkeys. Sixty-six maxillary central incisors were replanted or autotransplanted after extra-alveolar periods of 18 min. saline storage or 120 min. dry storage. The animals were sacrificed after 8 weeks and the teeth examined histometrically. Identical healing was found in the following experimental groups: replantation or autotransplantation after 18 min. and replantation with or without removal of periodontal ligament in the alveolus. A significant increase in replacement resorption (ankylosis) compared to the 18 min. replantation group was found in the following groups: replantation and autotransplantation after 120 min., replantation after removal of periodontal ligament on the root surface and autotransplantation after 120 min. to a socket where the tooth was extracted 18 min. earlier. Autotransplantation after 18 min. to a socket where a tooth had been extracted 120 min. earlier led to a significant increase in the amount of replacement resorption compared to transplantation to an 18 min. socket. Based on these findings, it is concluded that the presence of an intact and viable periodontal ligament on the root surface is the most important factor in assuring healing without root resorption. The length of the extra-alveolar period also seems to exert some influence upon the socket, enhancing the development of ankylosis.