Objective: To evaluate the stability of titanium alloy and stainless steel microimplant anchorage after immediate loading. Methods: One titanium alloy microimplant and one stainless steel microimplant were placed in one side of maxilla and the other side of mandible respectively in eight adult male mongrel dogs at random. 1.96 N of constant force was loaded immediately between two micro-implants in maxilla or mandible. Four dogs were sacrificed 4 and 12 weeks respectively after operation. Undercalcified sections longitudinal to the implants were made for histological observation and measurement of the bone contact ratio( BCR) between microimplant and bone interface. Results: All microimplants kept stable. The microimplants had favorable biological consistencies with the fiber and bone around them. The BCR increased with the healing time prolonged. The BCR of titanium alloy group was higher than that of stainless steel group. Conclusion: The healing mode of both microimplants is fibro-osseous integrations when immediate loading is applied. The titanium alloy microimplant is more stable than the stainless steel microimplant as an orthodontic anchorage.%目的:评估钛合金和不锈钢微植体支抗即刻负载的稳定性.方法:选用8只本地成年雄性犬,每只犬任选一侧上颌骨和对侧下颌骨各植入1枚钛合金和不锈钢微植体.同颌2枚微植体间即刻加载1.96 N的力.4周和12周时各随机处死4只实验犬,制作硬组织切片进行组织学研究.结果:所有微植体均没有松动、脱落.微植体与周围组织有良好的生物相容性,种植体周围有纤维组织和骨组织共同包绕.骨结合率随着愈合时间的延长而增高,钛合金微植体骨结合率高于不锈钢微植体.结论:即刻负载下,钛合金和不锈钢微植体支抗的愈合形式都是纤维骨性结合,均可保持稳定,钛合金微植体更为稳定.
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