不同局部托盘制取藻酸盐印模后的石膏模型精确性研究

目的：系统评价不同局部托盘制取藻酸盐印模后的石膏模型精确性。方法利用局部托盘的方法，通过灌注硬石膏，在上颌部位制作藻酸盐标准模型的印模。而后依次测量龈缘近中边缘至远中边缘（4牙位）距离，以及远中边缘至近中边缘（2牙位）的距离，将上述两种距离与正常标准值进行统计学对比分析。参照局部托盘选择材料的不同，将研究对象分为铝制和钢制局部托盘两组；参照测量时间的不同，划分为1h和12h两组，上述各组依次测量6次。结果在近中边缘至27远中边缘距离测定时，全部的模型组与标准之间的差异均有统计学意义（P＜0.05）；在远中边缘至近中边缘的距离对比分析时，标准与钢制托盘之间差异无统计学意义（P＞0.05），剩余各组模型与标准模型之间的比较差异有统计学意义（P＜0.05）；在时间对比方面，1h和12h两组模型进行统计分析，两个时间段之间的差异无统计学意义（P＞0.05）。结论在藻酸盐印模制取的过程中，远中边缘至近中边缘的距离与标准的实体更相吻合；而近中边缘至27远中边缘钢制与铝制托盘印模的准确性基本一致；在临床中，制作近中边缘至27远中边缘距离，以及远中边缘至近中边缘两种印模，材料以及石膏模型的规格比例之间的差异无统计学意义。

Study on accuracy of plaster model after alginate impression taken through using different trays

Objective To systematically review accuracy of gypsum model after Alginate Impression taken through using different trays.Methods Through perfusion of anhydrite, impression of alginate standard model was made by the method of local tray in the upper. Distance from proximal middle edge to distal middle edge of gingival margin （4 teeth）, and distance from distal middle edge to proximal middle edge （2 teeth） were measured respectively. The two distances were compared and analyzed statistically with normal standard values. Research subjects were allocated to two groups of aluminum local trays and steel local trays according to the different materials used by local trays, and subjects were also allocated to 1-hour group and 12-hour group based on different measuring time. All groups were measured 6 times respectively.Results In the measuring of distance from proximal middle edge to distal middle edge, the differences between all the model groups and the standard model were statistically significant （P〈0.05）. In the comparison and analysis of the distance from distal middle edge to proximal middle edge, the differences between the standard model and steel trays were not statistically significant （P=0.258）, and the differences between the standard model and the rest of the groups were statistically significant （P〈0.05）. In time comparison, the differences between 1-hour group and 12-hour group were not statistically significant （P〉0.05）.Conclusion During the production of alginate impression, the distance from distal middle edge to proximal middle edge is close to that of the standard model, and the precision of steel and aluminum trays impression is similar regarding the distance from proximal middle edge to distal middle edge. In clinical practice, for the production of two types of impressions of the distance from proximal middle edge to distal middle edge and the distance from distal middle edge to proximal middle edge, the differences of material, size and proportion of plaster model a