To elucidate the regenerative capability of the periodontal tissues, we carried out two experiments: (1) Regeneration of the gingival tissue following gingivectomy in rats. Ultrastructurally, regenerating junctional epithelium was similar in morphology to that of untreated animals and appeared to attach to the enamel after five days. Basal lamina and hemidesmosomes were produced faster at the enamel interface than at the connective tissue interface. Gingival tissue was completely regenerated seven days after the gingivectomy. (2) Regeneration of the cementum, periodontal ligament, and alveolar bone following intradentinal cavity preparation in dogs. In the early stages, the cavity was filled with an exudate and granulation tissue. Seven days after the operation, osteoblasts and cementoblasts were arranged regularly on the cut surface of the alveolar bone and dentin, respectively. Newly formed bone and cementum, and periodontal ligament grew to resemble pre-existing bone and cementum after 28-42 days. From these results, it is suggested that the periodontal tissues have an extremely high capability of regeneration.
