HEALING FOLLOWING SURGICAL-TREATMENT AND ROOT DEMINERALIZATION IN MONKEYS WITH PERIODONTAL-DISEASE

The potential for new attachment to root surfaces which had become devoid of attachment by mechanical removal or in conjunction with experimental periodontal tissue breakdown and subsequently had been conditioned with citric acid, was studied. Three adult monkeys (M. cynomolgus) were used. Periodontal pockets were produced during a 2-6 mo. period around the maxillary central incisors and 1st and 2nd premolars and around the mandibular central incisors by the placement of orthodontic elastics. Surgical treatment of the pockets was carried out with the use of a flap procedure. During surgery, the roots of the premolars on the right side of the jaws were first scaled and planed and subsequently treated with citric acid. Citric acid conditioning was not performed on the premolars of the left side. In the front tooth regions the surgical treatment included citric acid conditioning of the mandibular central incisors in 2 animals and of the maxillary central incisors in 1 animal. Surgical procedures were also carried out around the mandibular 2nd premolars and 1st molars which had not been exposed to periodontal tissue breakdown. Following flap elevation, the buccal bone plate was mechanically removed within an area corresponding to that of bone loss produced by the experimental periodontitis model in the maxillary premolars. The cementum layer of the surgically denuded portion of the roots was removed by root planing. In all treated teeth, a notch was prepared in the buccal root surfaces at the level of the alveolar bone crest. Six mo. following treatment the animals were sacrificed and histologic sections prepared. Linear measurements were made along the root surface from the apical border of the prepared notch to the apical termination of the junctional epithelium and to the crest of the alveolar bone. Cementum formation and new connective tissue attachment did not occur on root surfaces previously exposed to periodontal pockets and subsequently subjected to scaling and root planing or on root surfaces surgically deprived of their supporting bone and previously nonexposed cementum layer. Cementum formation and new connective tissue attachment also failed to occur following citric acid conditioning of root dentin surfaces. In all sections representing all 3 treatment groups, the attachment between the gingiva and the root was established by epithelium.