実験的咬合性外傷のサル歯周組織に及ぼす影響に関する研究

抄録

The purpose of this study is to make clear the effect of long term occlusal trauma on the periodontal tissue in monkeys as compared with the result of the former short term experiment, in addition to observe the influence of occlusal trauma on progression of gingival inflammation to the underlying tissue.
Two adult male Macaca irus monkeys were used. In order to create extra lateral force, cast gold high crowns extended mesially were set on mandibule left second molar (M₂) and contra lateral tooth (₂M) of each animal. The crown margin of M₂ was ill-fitted, and was placed subgingivally to cause gingival inflammation, the other hand the crown margin of ₂M was located coronally to the gingival crest to avoid marginal irritation.
Oral examination was made every four weeks to check gingival condition, and standerdized radiographs were taken to investigate bone and periodontal space changes. Each animal was sacrificed after 12 and 24 weeks and tissue sections were prepared for histological examination.
The results were as follows:
1. Vertical bone resorption was observed radiographically in 8 and 12 weeks after giving extra lateral force using mesially extended high crown.
2. Angular resorption of alveolar bone crest was also observed histologically, but apical-migration of junctional epithelium did not occured.
3. Gingival inflammation was caused by ill-fitted crown which margin was placed subgingivally. However inflammatory cell infiltration always located coronally to the transseptal fiber though affected by occlusal trauma, and did not progress to the periodontal ligament area.
4. From the result of the former short term experiment, it had been observed that periodontal tissue had been severely destructed in 4 weeks by occlusal trauma, but in this long term study the destructed tissue was partially repaired in about 16 weeks because of moving of the test teeth by excessive occlusal force.