几种常用印模材制取固定义齿模型的三维精度比较

Three-dimensional accuracy of four impression materials for fixed denture

目的 :评价硅橡胶类、琼脂类、藻酸盐类 (水粉剂与糊剂 )等 4种临床常用印模材料的取模精度。方法 :分别用 4种模型材料制取 10个同一金属实验模具的石膏模型 ,用测量显微镜测量金属模型和石膏模型上各标志点的距离 ,精度为 0 .0 0 1mm,所得数据进行统计分析。结果 :藻酸盐糊剂印模材料制取的石膏模型在长径方向上与其他组有显著差异 ,且超出了临床允许的精度范围 ;硅橡胶印模材料制取的石膏模型线性变化率最小且比金属模型略大 ;琼脂印模材料与藻酸盐印模材料 (水粉剂 )制取的印模在三维尺寸变化率方面无显著差异。结论 :藻酸盐糊剂印模材料取模精度差 ;硅橡胶印模材料的取模精度最高 ,且可以起到补偿义齿后续操作中的收缩及提供冠桥粘结剂间隙的作用 ;琼脂印模材料具有印模精度高 ,操作比较简单 ,且价格易于接受等优点 ,值得在临床应用中进一步普及和推广。

砄bjective:To investigate the three dimensional accuracy of four impression materials for fixed denture:silicone(OX),hydrocolloid(HT) and two kinds of alginate impression(FC and ZS).Methods:Ten plaster replication models for each impression materials were made on the same metal master cast respectively, vertical and horizontal dimensions between landmarks on the masters and plaster casts were measured with an optical microscope. ANOVA was used to compare the measurements among the materials.Results:The difference between the masters and casts in horizontal distances measured on ZS produced models was bigger than that on other impression material produced ones ( P <0.01) and beyond clinical requirment.The difference between the masters and casts in all measured dimensions on OX produced models was the smallest.Conclusion:Alginate paste is not accurate enough for denture model,while silicone is.The hydrocolloid material is relatively accurate.