Influence of osteoporosis and aging in the bone structure to biomaterial

本实验以去卵巢大鼠为模型，研究种植后骨质疏松对种植体周围骨结构的影响。本研究选用30~32岁雌性Wistar大鼠的胫骨。将羟基磷灰石(HA)和钛(Ti)棒植入64只大鼠的胫骨内。植入后6周，摘除卵巢28只，假手术26只，处死10只大鼠(对照组)。分别于术后4、8、16周处死大鼠。组织学检查HA和钛种植体周围骨组织的反应。实验结果如下：1)与假手术组相比，去卵巢组大鼠体重明显增加。术后4、8、16周，去卵巢组大鼠股骨远端骨小梁体积百分比明显低于假手术组。这些结果表明，该模型代表了骨质疏松。2)“OVX”中HA周围的成熟松质骨按时间顺序被吸收，但有些在16周时仍保持不变。在“假”组，大量的骨小梁残留在HA周围，并与皮质骨相连，作为“对照”，结缔组织在HA与骨界面上的面积按时间顺序增加。术后16周，种植体表面可见纤维组织形成。3)在“去卵巢”的股骨远端，钛周围仍有少量成熟的松质骨存在，而周围骨的厚度在1~6周时迅速增加。与“OVX”相比，接近“假”的成熟骨数量更多。这些发现表明，在骨质疏松的情况下，HA和Ti的骨反应，特别是在骨-种植体界面的反应是不同的。

The aim of this experimental study was to evaluate the influence of osteoporosis induced after implantation on bone structure around dental implants using ovariectomized rats. Tibiae of 30 to 32-old female Wistar rats were used in this study. Hydroxyapatite (HA) and titanium (Ti) rods were inserted into tibiae of 6 4 rats. Six weeks after implantation, 28 rats were ovariectomized (ovx), 26 rats were sham-operated (sham) and 10 rats were sacrificed (control). Four, 8 and 16 weeks following the operation, the rats were sacrificed. The reaction of the bone tissue surrounding HA and Ti implants was examined histologically. The results can be summarized as follows.1) The body weight of "ovx" rats markedly increased compared with "sham" rats. Trabecular bone volume percent in distal region of femurs of "ovx" was significantly lower than that of "sham" 4, 8 and 16 weeks following the operation. These findings showed that the this model represents osteoporosis.2) Mature trabecular bone around HA in "ovx" was resorbed chronologically, but some remained at 16 weeks. In "sham", a large amount of trabecular bone remained around the HA and was connected to the cortical bone as seen m "control" The area of connective tissue increased chronologically m the HA and bone interface. Sixteen weeks following the operation, fibrous tissue was observed on the implant surface.3) Very small amount of mature trabecular bone remained around Ti in "ovx" as seen in distal region of femurs, whereas the thickness of surrounding bone rapidly increased at 1 6 weeks. A greater amount of mature bone was found close to Ti m "sham" compared to that in "ovx". These findings suggest that the bone reaction, especially in the bone-implant interface, is different between HA and Ti in cases of osteoporosis.