[Histopathological observation of periodontal tissue by tipping movement toward the hydroxyapatite-packed socket].

Tipping movement in orthodontic therapy, which is often performed even in the absence of the adjacent tooth, is represented by the movement following tooth extraction. Such tipping movement in the absence of the adjacent tooth depends not only upon the magnitude of orthodontic force as classified into Stoner 4D, but also upon the condition of the extracted wounds. To evaluate the clinical applicability of HAp-packing used in combination with tipping movement, histopathological investigation was performed in the periodontal tissue with tipping movement toward the adjacent to HAp-packed socket. HAp packing into the extracted wound cavity produced no significant changes in quantitative tipping movement compared with non-HAp packing. HAp packing into the extracted wound cavity, followed by tipping movement, produced compressed sides not only for the moved tooth but also for the anchor tooth. Resorption and disappearance of alveolar septum were observed on the compressed sides of both these teeth for all experimental sides. HAp in an amount enough to meet the narrowing of the extracted wound cavity, associated with tipping movement was discharged from the suture surface. In the same region, fibrous connective tissue lay between the dental root and the HAp mass, which were not adjacent to each other. The fibrous connective tissue presented temporal bone regeneration so as to surround the tooth. Apart from the moving distance, the tissue change showed no essential difference either for a weak force or for a strong force. The above results revealed the usefulness of HAp packing into the extracted wound cavity for tipping movement of the adjacent tooth in the direction of the wound cavity and immediate move ability after extraction.