The role of the necrotic periodontal membrane in cementum resorption and ankylosis

Abstract Teeth replanted with non‐vital periodontal membranes demonstrate a high incidence of root resorption and ankylosis. It has been suggested that necrotic periodontal membrane remnants actively stimulate resorption of the resistant cementum layer. The aim of this study was to examine resorption and ankylosis patterns following replantation of teeth with chemically denuded root surfaces and, by extrapolation from these data, to suggest a role for the necrotic periodontal membrane in resorption and ankylosis. Monkey incisors were replanted after endodontic therapy and immersion in 10% sodium hypochlorite. Teeth were either examined with scanning electron microscopy at intervals from 1 day to 8 wk, or subjected to light microscopic examination, using a morphometrical evaluation technique, at 8 wk post‐replantation. Only a few macrophage‐like cells, in relation to shallow resorption lacunae, were observed by 8 wk. Histologically, the alveolar bone had approached an apparently intact cementum surface in 93% of the morphometrically recorded points. This bone appeared to lie in close approximation to the cementum surface. Denuding the root surface of periodontal membrane prior to replantation demonstrated the resistance of the cementum to colonization and resorption in the absence of stimulation from necrotic periodontal membrane remnants. Furthermore, it revealed that bone replacing the periodontal membrane space grew from the alveolus towards the cementum, to which it appeared unable to fuse due to the absence of significant resorption. Thus, removal of a non‐vital periodontal membrane may result in slower destruction of tooth substance following replantation of teeth with severely damaged periodontal membranes.