The superstructure desing of a newly developed one-stage zirconia implant

本研究的目的是研究上部结构设计对新开发的一期氧化锆种植体骨界面的影响，并为一期氧化锆种植体的上部结构设计提供有用的信息。在7只雌性猕猴下颌骨臼齿和前臼齿无牙区左右两侧的预备骨窝中，通过轻叩插入置入2颗氧化锆种植体。种植体放置3个月后，将3种金属上部结构粘接在种植体上。种植体按上部结构设计分为3组。在第一组（Gl）中，将单个金属冠粘接在右侧近中种植体上。在第二组（G2）中，用金属桥连接左侧两个种植体。在第三组（G3）中，用金属桥连接右远端种植体和邻近的第二磨牙。加载12个月和24个月后，处死动物，制备植入物未钙化切片，光镜下观察。还进行了组织形态学分析。组织学上，所有种植体均可实现骨与种植体的直接界面，三组间无明显差异。在为期12个月的组织形态学分析中，G1期种植体的骨接触率低于其他组。然而，在24个月的研究中，三组骨接触率无显著差异。结果表明，与邻牙连接的一期氧化锆种植体比采用上部结构连接的单站立种植体具有更高的骨接触率。

The purpose of this study was to examine effects of superstructure designs on bony interface of a newly developed one-stage zirconia implant, and to present useful informations on the superstructure design of one-stage zirconia implant. Two zirconia implants were placed by tapping insertion into the prepared bone socket at left and right sides of molar and premolar edentulous areas of the mandible of each of seven female adalt monkeys (Macaca fuscata). Three months after implant placement, three kinds of metal superstructure were cemented on the implants. The implants were divided into 3 groups according to superstructure designs. In group 1 (Gl), a single metal crown was cemented on the reight mesial implant. In group 2 (G2), a metal bridge was cemented connecting left two implants. In group 3(G3), a metal bridge was cemented connecting right distal implant and neighboring second molar. After 12 months and 24 months of loading, the animals were sacrificed and undecalcified sections involved implants were prepared and examined by light microscopy. Histomorphometric analyzes were also performed. Histologically, direct bone-implant interface was generally achieved in all implants, and there was no clear difference among three groups. In histomorphometric analyzes of a 12-month study, bone contact ratio of the implant in G1 was lower than others. However, in 24-month study, no significant difference of bone contact ratio was obtained among three groups. These results suggest that one-stage zirconia implant connected with neighboring tooth could achieve higher bone contact ratio than single standing implants whichever they were connected by superstructure.