The effects of exclusion of epithelium from healing periodontal pockets.

Epithelium was excluded experimentally from artificially induced periodontal pockets by cutting off the crowns of vital teeth and covering the roots with mucoperiosteal flaps. This procedure was carried out on 58 teeth in eight rhesus monkeys and specimens recovered at from five to 36 weeks postoperatively. Thirty-eight (66%) of the teeth remained completely covered by soft tissue for the duration of the experiment. Up to 4.4 mm (mean = 0.9 mm) of new attachment with cementum and attached collagen fibers was found on both the sides of the roots and the cut ends, but root resorption and downgrowth of epithelium over root surfaces were about equally common. Thus, even when epithelium is excluded from healing periodontal pockets, reattachment with new cementum and attached collagen fibers is not consistently achieved, even after periods of 36 weeks. Root resorption and ankylosis are major complications. Although most new attachment appears to result from cells originating in the periodontal ligament, it can also arise from cells from the gingival connective tissue.