Effect of inadequate fits of superstructures on surrounding tissue

拔除2只Beagle犬双侧下颌第四前磨牙和第一磨牙，3个月后各植入3个固定器。在固定装置插入4个月后，将基牙连接到每个固定装置上，然后取印模。在下颌骨两侧各3个基牙上设置一个连接的上层建筑，并以10NCM的扭矩拧紧金螺钉。除实验侧中部外，上层建筑与基牙之间的垂直距离约为14 0~2 0 0μm，其余均与基牙被动配合，观察5周或14周后取材进行组织学检查。适配组和不适配组的组织学结果相似，且大部分固定物表面直接面对骨组织。在配合组和错配组中，标准化的X线片显示固定物周围的骨高度没有明显变化。在此基础上，参照口腔舌部组织块制作模型。

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.