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目的通过组织形态学观察和定量测定,比较拔牙创对种植体—骨界面愈合进程的影响,并对正畸微种植体骨整合的安全范围进行探讨。方法 12只雄性Beagle犬,按不同愈合时间段(1、3、8、12周)随机分成4组,建立邻近拔牙创植入正畸微种植体实验动物模型。在植入微种植体后愈合的第1、3、8、12周处死各组动物,制备含种植钉的硬组织切片,观察组织学形态,并测定微种植体—骨界面骨接触率(BIC)。结果实验组和对照组在植入后第3周开始出现组织学变化的明显差异:实验组骨界面骨吸收活跃;对照组骨界面出现新生骨层,周边存在活跃成骨细胞。对照组在植入后前8周,BIC值随着时间的增加而增加。实验组BIC值在植入3周后有所下降,到第8周达到峰值(80.08%),随后进入平台期。两组BIC差异表现在植入后第3周:实验组BIC(44.35%)小于对照组(55.46%),二者差异有统计学意义(P<0.01)。结论拔牙创对微种植体周围骨重建进程会产生影响,早期表现为加重骨吸收,但在随后的时间里骨形成效应会迅速加强。
Objective To investigate the effect of tooth extraction on the healing process of implant-bone interface through histopathological observation and quantitative determination, and discuss the safety scope of ortho-micro-implant osteosynthesis. Methods Twelve male Beagle dogs were randomly divided into 4 groups according to different healing time (1, 3, 8 and 12 weeks). The experimental animal model of orthodontic micro-implants with adjacent tooth extraction was established. Groups of animals were sacrificed on the 1st, 3rd, 8th and 12th week after the micro implants were implanted, and the hard tissue sections containing implants were prepared. The histological morphology was observed and the bone contact rate at micro-implant-bone interface (BIC ). Results The histological changes of the experimental group and the control group began to show significant difference at the third week after implantation. The experimental group had active bone absorption at the interface and the new bone layer at the bone interface in the control group with active osteoblasts in the periphery. In the control group, BIC values increased with time in the first 8 weeks after implantation. The BIC value of the experimental group decreased after 3 weeks of implantation and reached the peak value of 80.08% by the 8th week, then entered the plateau phase. The difference of BIC between the two groups showed that at the third week after implantation, the BIC in the experimental group (44.35%) was smaller than that in the control group (55.46%), the difference was statistically significant (P <0.01). Conclusion Tooth extraction has an effect on the process of bone remodeling around micro-implants. Early manifestation is to increase bone resorption, but bone formation effect will be strengthened rapidly in the following time.