Effect of inadequate fits of superstructures on surrounding tissue

取2只beagle犬的双侧下颌第四前磨牙和第一磨牙，3个月后各插入3个固定装置。在每个夹具插入4个月后连接基台，然后进行印模。在下颌骨两侧各3个基台上设置连接的上部结构，并以10 Ncm的扭矩拧紧金螺钉。除了实验侧的中间结构外，上部结构被动贴合在基台上，其与基台之间的垂直间隙约为140 ~ 200 μ m。观察5周或14周后取样组织块（包括植入物）进行组织学检查。适合组和不适合组的组织学结果彼此相似，并且大部分夹具表面直接面向骨组织。在适合组和不适合组中，标准化骨造影显示固定装置周围的骨高度没有明显变化。为了进行有限元分析，首先建立了简化模型。然后参照组织块的颊舌部分制作模型。

Bilateral mandibular fourth premolars and first molars from 2 beagle dogs were extracted, and 3 fixtures for each site were inserted 3 months later. Abutments were connected on each fixture 4 months after insertion of the fixture, followed by impression taking. A connected superstructure was set on 3 abutments in each side of mandible and gold screws were tightened with a torque of 10 Ncm. Superstructures were passively fit to the abutments expect for the middle ones of the experimental side, which were given vertical clearance of about 140〜200 μ m between the superstructures and abutments.The tissue blocks including the implants sampled after 5 or 14-week observation were used for the histological examination. Histological findings from both the fit and the misfit groups resembled to each other, and large percentage of the fixture surface directly faced to the bone tissue. In both fit and misfit groups, standardized rentogenographs showed no obvious change in the bone height around the fixtures.For the finite element analysis, the simplified model was created at first. Then the model with reference to the bucco-lingual section of the tissue blocks was made.