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目的:研究四种不同材料熔模在完成后不同时间边缘浮升量的变化及对铸造冠边缘精度的影响。方法:用统一标准模具翻制40个超硬石膏代型,随机分为四组,每组10个,分别采用日进公司的Casting Pattern Resin,松风Hard嵌体蜡、BEGO牙冠蜡和国产嵌体蜡(分别简称日进、松风、BEGO和国产),于实验室内在石膏代型上分别制作10个熔模,熔模完成10、20、30、60、120、240 min时,在投影测量仪下测量熔模边缘的浮升量,并于熔模完成30 min后采用同一种方法包埋、铸造,比较铸造冠边缘的浮升量。结果:①在10～30 min,各种熔模的边缘浮升量逐渐变大,各时间点间有高度差异性(P<0.01);30～240 min,各种熔模的浮升量变化不明显,各时间点间无差异性(P>0.05)。②在各时间点,日进熔模的边缘浮升量最小,国产熔模的浮升量最大,松风和BEGO熔模居中,四种熔模间有差异性(P<0.05)。③日进熔模制成的铸造冠的边缘浮升量最小,国产熔模铸造冠的浮升量最大,松风和BEGO铸造冠居中,四种熔模铸造冠间有差异性(P<0.05)。结论:不同种类的熔模材对熔模精度的影响不同,在本试验中,日进熔模的边缘精度最高;熔模完成后在10 min时精度最高,30 min后对精度的影响较小;日进熔模制成的铸造冠的边缘精密性最高。
OBJECTIVE: To study the variation of edge lift at different times after the completion of four different types of investment dies and the influence on the accuracy of edge of casting crown. Methods: A total of 40 standard hard cast plaster cast, were randomly divided into four groups of 10, respectively, using the company’s Casting Pattern Resin, Songfeng Hard inlay wax, BEGO dental crown wax and made Inlaid wax (referred to as Riyadh, pine breeze, BEGO and domestic), in the laboratory plaster cast on the production of 10 molds, respectively, 10,20,30,60,120,240 min after melting at Under the projection measuring instrument, the amount of buoyancy on the edge of the investment mold was measured. The same method was used to embed and cast 30 minutes after the completion of the investment, and the amount of buoyancy at the edge of the cast crown was compared. Results: (1) At 10 ~ 30 min, the edge buoyancy of various fuses increased gradually, and there was a high degree of difference between the time points (P <0.01). After 30 ~ 240 min, Not obvious, no difference between the time points (P> 0.05). (2) At each time point, the edge buildup was the smallest in the daily melt buildup, the buildup of the domestic melt buildup was the largest, and the blow mold and BEGO melt buildup were the middle one. There were differences among the four fuses (P <0.05). (3) The rim buoyancy of the casting crown made by Nisshin Molding is the smallest, the buoyancy of the domestic investment casting crown is the largest, and the crown of the breeze and BEGO casting crown is the center, there are differences between the four investment casting crowns (P <0.05 ). Conclusion: Different kinds of melt-infused materials have different effects on the precision of the fuses. In this experiment, the edge precision of the fuels-in-place is the highest. The precision is the highest at 10 minutes after melt-infiltration and the accuracy is less affected after 30 minutes ; Japan into the casting crown made of the highest precision.