Résumé
The purpose of this study was to evaluate the material for fixed type retainer, allowing physiologic tooth movement. and proper remodeling of periodontal tissue during retention period. The present study was performed to observe the histologic changes of periodontal tissue after application of different types of fixed type retainer after orthodontic tooth movement in young adult dogs. For this study, 4 young adult dogs were used as a experimental animal and experimental group was divided into three groups ; experimental group 1 contained right side maxillary third incisors and canines, experimental group 2 contained contralateral teeth of same animals, and control group contained mandibular premolars. And each dogs were applied the 4 different types of fixed type retainer to experimental group 1. The experimental teeth were ligated on the Sentalloy closed coil spring(R)(Tomy Co., Japan) from maxillary third incisors and canines and applied orthodontic force at initial 200gm-forced during 1 week. All the experimental animals were sacrificed on the 3rd week after the orthodontic teeth movement and then the specimens were taken, fixed in formalin, embeded in parafin, sectioned 6-8micrometer in thickness and stained with Hematoxylin-Eosin staining, and Masson's trichrome staining method. Examined under the light microscopy. The following results were observed. 1. There were observed that decreased infiltration of giant cells in pressure side and increased the new bone forming in tension side on the specimen of 6-stranded 0.0195' Respond(R)(G&H Co., U.S.A.) group. Periodontal ligament fibers were much compressed or elongated in 3-stranded 0.018', 0.020' Dentaflex(R)(Dentarum Co., Germany), and Superbond C&B(R)(Sun Medical Co., Japan) groups. 2. In experimental group 1, necrotic bone inside the alveolar bone of pressure side, forming of the sharpey's fiber in osteoid tissue, and remodeling of the periodontal ligament were observed in all animals. 3. In experimental group 2, it was observed that the amount of bone resorption was equal or decreased in pressure side, and increased new bone forming and significantly decreased infiltration of giant cell than the experimental group 1. By this results, it considered that 6-stranded Respond(R)(G&H Co., U.S.A.) wire was the most useful material allowing early periodontal tissue remodeling.