数字化口腔修复(10)——传统印模对游离龈位置影响的三维分析

Digital restorative dentistry and prosthodontics(10)——Three-dimensional analysis of the effect of the traditional impression on the free gingival displacement

目的：利用三维模型分析法比较不同印模材料印模对游离龈位置的变化量。方法：随机选取10位健康人的60颗上前牙为实验对象,实验前后分别行口内光学扫描（CERECAC Omnicam）,获取光学模型数据。用3种印模材料（藻酸盐、聚醚、加成型硅橡胶）取口内印模,分别灌制超硬石膏模型,并扫描石膏模型获取三维数据。将口内扫描的光学模型数据通过软件（Geomagic Qualify 2013）与石膏模型扫描的光学模型数据进行重叠,比较不同印模材料制取印模后游离龈位置变化量。结果：3种印模材料印模后的游离龈位置变化量的差异有统计学意义（P〈0.05）;藻酸盐印模与聚醚印模的游离龈位置的差异无统计学意义（P〉0.05）;而加成型硅橡胶印模与藻酸盐印模和聚醚印模的游离龈位置之间的差异均有统计学意义（P〈0.05）;加成型硅橡胶印模的游离龈位置的变化量最大（P〈0.05）。结论：印模过程所产生的压力会导致游离龈位置发生不同程度的改变,不同印模材导致游离龈位置的改变不一样;口内光学印模可以精确评价游离龈位置。

Objective：Utilizing three-dimensional（3D）model analysis to evaluate the amount of free gingival displacement produced by the impressions with different impression material. Method：60 anterior teeth from 10 healthy volunteers were included randomly as the test subjects. An intraoral digital impression were getted prior to the test by intraoral optical scanning（CEREC AC Omnicam）. Then using three different impression materials（alginate,polyether,and addition silicone） to make impression in mouth. Stone casts were obtained after the impressions,respectively,and then 3D models were got by scanning with CEREC AC Omnicam. The 3D models were superimposed with those of intraoral digital impression by Geomagic Qualify 2013 soft and the amount of free gingival displacement produced by the impression of different impression materials were evaluated. Result：The displacement amount of free gingival among three impressions of different impression materials were significantly different（P〈0.05）. The amount of free gingival displacement between alginate and polyether were not significantly different（P〈0.05）,but the difference were both significant when compared with that of addition silicone and alginate and polyether（P〈0.05）. The free gingival displacement changed mostly in addition silicone among the three kinds of impression materials（P〈0.05）. Conclusion：The pressures produced by different impression materials will make the free gingival displacement,which was different among different impression materials. Intraoral digital impression can be used to evaluate the position of the free gingiva accurately.