摘要
目的 本实验旨在观察印模材料对工作模型精度的影响以及模型材料与印模材料间的配伍性。方法 将普通石膏、硬石膏、超硬石膏3种模型材料分别灌入金属印模、硅橡胶印模、藻酸盐印模和琼脂印模中,用激光热膨胀仪(日本产1000型)测量各组试件的凝固时的尺寸变化,将所得数据换算成尺寸变化率并进行统计分析。结果 ①普通石膏在金属印模中呈现为收缩,而在硅橡胶,藻酸盐及琼脂印模中为高度膨胀,其在各种印模材料中的凝固尺寸变化率有显著性差异。②硬石膏在四种印模材料中的凝固尺寸变化率均小于0.15％,尤以在金属及藻酸盐印模中尺寸变化较小,性能较稳定。③超硬石膏在金属印模中呈现为膨胀,在硅橡胶及藻酸盐印模中尺寸变化率稳定,均不超过0.10％。而在琼脂中表现为明显的收缩。结论 各种模型材料在同一种印模中的尺寸变化率不同。同一种模型材料在不同的印模中尺寸变化率也各有差异。提示模型的尺寸变化率同印模材料与石膏的配伍有密切关系。
Objective To study the effect of impression material on the precision of working models. Methods Three kinds of model materials (general stone,hard stone and superhard stone)were poured into four kinds of impressions respectively and their dimensional changes were tested. Dimensional change rates were calculated and analyzed to predict the precision of working models. Results General stone shrinked in the metal die while expanded extensively in the silicone rubber, alginate and agar die. The setting expansion rate of general stone in different model dies differs significantly and unstable,which is not suitable as working models. Setting dimensional change rate of hard stone in all the four dies were less than 0. 15% especially in metal and alginate dies,which is stable and sutable for making general working cast. While showing an apparent expansion trend in metal die and an obvious shrinking behavior in agar die,setting dimensional change rate of superhard stone in silicone and alginate dies were stable and less than 0. 10% which can be used for precision casts. Surface fineness of casts formed in agar impressions by hard and superhard stone were not as good as expected thus can not be used into cast duplication. General stone has the highest expansion rate as well as good surface fineness,so it can be improved to be appropriate duplication materials. Conclusion This study indicated that the dimensional change rates of stone are related with the corresponding elasticities of impressions and the compatibility of stone.
出处
《口腔材料器械杂志》
1999年第2期78-82,共5页
Chinese Journal of Dental Materials and Devices
