犬拔牙创愈合对相邻微种植体最大拉拔力值的影响

Effect of wound healing after tooth extraction on maximal pull-out force of adjacent micro-screws

目的探讨拔牙创骨质结构改建对相邻微种植体作为正畸支抗的稳定性的影响,为微种植体的临床运用提供依据。方法 8只雄性Beagle犬按不同愈合时间段(1、3、8、12周)随机分成4组,每只Beagle犬拔除第3和第4双尖牙(P3,P4),实验微种植体邻近拔牙区域,对照微种植体位于第2双尖牙(P2)和第1磨牙(M1)区域,共植入微种植体128枚。选择96个微种植体组织块,通过拉拔试验测定微种植体的最大拉拔力值(pull-out force,POF)并将结果进行统计学分析。结果实验组和对照组POF值在第1周内没有表现显著性差异(P>0.05),在第3周对照组POF显著高于实验组(P<0.05)。两组POF高峰值均出现在第8周组。在前8周里,实验组和对照组的POF均随着时间得延长而增加,到第12周出现回落。实验组POF在各时间段均存在显著性差异(P<0.05)。而对照组仅第12周与第3、8周POF值表现显著性差异。结论邻近拔牙创植入的微种植体在无载荷愈合期可以保持稳定性。但拔牙创的早期愈合可能会加重微种植体-骨界面的炎症反应和骨吸收效应,即刻加载风险较大。

Objective To provide the evidence for the clinical application of micro-screws by studying the effect of bone structure reconstruction after tooth extraction on the stability of its adjacent micro-screws as an implanted anchorage.Methods Eight male Beagle dogs were randomly divided into 4 groups according to the different healing periods of time（1,3,8,and 12 weeks）after tooth extraction.The third and fourth canine teeth（P3 and P4） were extracted from each dog.A total of 128 micro-screws were implanted into the adjacent areas of P3,P4,P2,and the first motor tooth（M1） after extraction.The maximal pull-out force（POF） value for 96 tissue masses of micro-screws was tested and analyzed.Results No significant difference in the POF value was found between the experimental and control groups during the first week after tooth extraction（P〉0.05）.The POF value was significantly lower in control group than in experimental group during the third week after tooth extraction（P〈0.05）.The POF value reached its peak in both groups at week 8.The POF value increased with the prolonged time in the first 8 weeks and began to decrease from week 12.A significant difference in POF value was observed in experimental group at different periods of time and in control group between week 12 and weeks 3 and 8（P〈0.05）.Conclusion Implanted micro-screws adjacent to the extraction wounds can maintain the anchorage stability during the non-load healing period.The early healing of extraction wounds may exacerbate inflammatory reactions on the interface between implanted micro-screws and bone,and promote the bone absorption efficacy,thus increasing the immediate loading risk.