2种石膏基包埋料对铸造精度影响的比较研究  

Comparison of casting precision of two kinds of commercially available gypsum-bonded investment with different setting and thermal expansion characteristics

作　　者：童徐[1,2] 赵耀[1] 孟玉坤[3] 

机构地区：[1]口腔疾病研究国家重点实验室,四川大学,四川成都610041 [2]重庆医科大学附属口腔医院修复科,重庆400015 [3]四川大学华西口腔医院修复科,四川成都610041

出　　处：《华西口腔医学杂志》2009年第6期649-652,共4页West China Journal of Stomatology

摘　　要：目的研究2种商品化包埋料Cristo balite MicroⅡ和Cristo Quick的膨胀性能及其对铸件精度的影响。方法选用传统型石膏基包埋料Cristo balite MicroⅡ和快速加热型石膏基包埋料Cristo Quick,按粉液质量比为1∶3的比例混合调拌,分别测定2种包埋料的凝固膨胀率和热膨胀率。以预制标记点的圆盘形蜡型为铸件原型,采用0.45mm陶瓷纤维衬层铸圈,分别用2种包埋料包埋铸造,测量铸件在相应标记点方向上的尺寸变化率。结果1)Cristo balite MicroⅡ的凝固膨胀率、热膨胀率和总膨胀率分别为0.68、1.18和1.86,Cristo Quick则分别为0.94、1.03和1.97。2种材料的凝固膨胀率和热膨胀率的差异有统计学意义(P<0.05),而总膨胀率的差异无统计学意义(P>0.05)。2)在衬层厚度相同的情况下,采用2种包埋料铸造的铸件,其尺寸变化率的差异无统计学意义(P>0.05)。结论本研究选择的2种石膏基包埋料膨胀量相同但膨胀特性不同,对铸造精度都没有影响。Objective To investigate expansion characteristics of two kinds of commercial investment （Cristo balite Micro Ⅱ and Cristo Quick）, and their effects on cast accuracy of a dental Ag-Pd casting alloy. Methods Two kinds of investment were mixed at the ratio of 1：3. The setting and thermal expansion curves of the investment were recorded according to the requirements of ISO7490 and expansion rate calculated, respectively. Plate-like wax-patterns with pre-marked points were invested in casting rings （lined with ceramic fiber liners with thickness of 0.45 mm）. Castwell M.C dental alloy were melted with gas flame and cast with a centrifugal casting machine. The differences between the castings and the wax patterns at corresponding points were calculated to represent the dimensional changes of the investment. Results The setting, thermal and total expansion rates were 0.68, 1.18, 1.86 for Cristo halite MicroⅡ, and 0.94, 1.03, 1.97 for Cristo Quick. The setting and thermal expansion rates were statistically significant between two kinds of investment （P〈0.05）, while not for the total expansion rates （P〉0.05）. Effect of different investment on the precision of castings was not statistically significant（P〉0.05）. Conclusion Within the scope of this study, gypsum-bonded investment with similar total expansion rates but different expansion characteristics has no effect on the casting precision of Ag-Pd dental alloys.

关 键 词：石膏基包埋料 牙科铸造合金 线性膨胀 铸造精度 

分 类 号：R783[医药卫生—口腔医学]