GUIDED TISSUE REGENERATION - COMPARISON OF BIOABSORBABLE AND NON-BIOABSORBABLE MEMBRANES - HISTOLOGIC AND HISTOMETRIC STUDY IN DOGS

THIS STUDY EXAMINED HISTOLOGIC AND HISTOMETRIC RESPONSES to 2 bioabsor bable membranes made from a synthetic copolymer of glycolide and lacti de. They were tested for their biocompatibility, resorption characteri stics, and ability to support periodontal regeneration. Expanded polyt etrafluoroethylene (ePTFE) was used as control. Nine fox hound dogs wi th no periodontal disease were used. They were sedated and their teeth thoroughly scaled and root planed. Plaque control was maintained. Two weeks later, each dog was anesthetized using gas anesthesia. Buccal a nd lingual mucoperiosteal flaps were reflected in the mandibular premo lar areas. Randomly selected, buccal alveolar bone was reduced on the 2nd and 4th premolars to a level 5 to 8 mm apical to the cemento-ename l junction creating a Class II buccal furcation defect on one quadrant , while the other quadrant received a Class II buccal defect only on t he 4th premolar. Root surfaces were denuded of periodontal ligament an d cementum, and notches were placed at the bone level of each root. In one quadrant, one site received Type I membrane and the other site re ceived Type II. The contralateral quadrant received ePTFE. Flaps were positioned slightly coronally and sutured. Sutures were removed 1 week later. One month after surgery, 3 dogs were sacrificed and ePTFE barr iers were removed from the remaining 6 dogs. Of these, 3 were sacrific ed 3 months after surgery and the other 3 at 6 months. Undemineralized experimental tissues were embedded in methylmethacrylate and 8 to 10 mu m thick sections were cut in a bucco-lingual direction throughout t he mesiodistal extension of the tooth. These sections were evaluated b y descriptive histology and linear measurements of the periodontal tis sues made. A two-factor analysis of variance was carried out on these measurements to test for differences between control and test membrane s within an animal for connective tissue attachment, cementum, bone, a nd epithelium. Analyses were performed on data 1, 3, and 6 months post -healing. Histologic and histometric evaluation demonstrated that, in spite of early resorption of resorbable membranes associated with the normal inflammatory reaction, the reformation of a connective tissue a ttachment was favored by the placement of the membranes. New cementum with inserting collagen fibers was observed on the previously denuded surfaces of test roots, similarly to that seen in the controls. Hence, these findings indicate that, from a clinical and histological stand point, similar results can be achieved in guided tissue regeneration p rocedures, whether bioabsorbable barriers or the non-bioabsorbable ePT FE is applied.