不同制作工艺对金属基底边缘适合性影响的实验分析

目的：比较CAD／CAM制作的蜡熔模和树脂熔模与传统滴蜡法制作的蜡熔模对金属基底边缘适合性影响的差异。方法：采用标准模具制作标准代型18个，随机分为A、B、C三组，每组6个，A组代型滴蜡法制作蜡熔模，B组代型CAD／CAM制作蜡熔模，C组代型CAD／CAM制作树脂熔模。每一代型及熔模进行四点标记，分别进行包埋铸造，按标记点就位，对每一个代型就位后的金属基底用Leica显微镜在四个标志点对垂直边缘缝隙进行拍照，用Image-ProPlus6．0进行测量后，使用SAS9．13对结果进行方差分析及t检验。结果：A组：68．20±24．30μm；B组：46．31±23．43μm；C组：60．58±21．87μm。所有试件的垂直边缘缝隙均在120μm以内。经方差分析及t检验，三组之间（P=0．0061）差异有统计学意义，A、C两组（P=0．2600）之间差异无统计学意义，A组与B组（P=0．0027）、B组与C组（P=0．0343）之间差异均有统计学意义。结论：CAD／CAM制作的蜡熔模与CAD／CAM制作的树脂熔模、传统滴蜡法制作的蜡熔模相比，经铸造后的试件具有较好的边缘适合性。CAD／CAM与传统铸造法结合能获得边缘适合性良好的修复体。

A vitro study of marginal adaptation of different fabrication methods on copings

Objective： To compare the marginal adaptation of casting restorations whose wax pattern fabricated by traditional method and CAD/CAM respectively and resin pattern fabricated by CAD/CAM. Methods： Eighteen type IV stone dies were pored with a silicone impression, and divided into A, B, C groups randomly. Six wax patterns for full-coverage coping crowns were fabricated by a traditional method in A group, while six wax patterns and six resin patterns were fabri- cated by a CAD/CAM system in B and C groups, respectively. All the patterns were invested and casted to fabricate crowns. The crowns were seated on the dies according their symbol sites. Their vertical marginal gap was taken pictures by Leica microscope, measured using Image-Pro Plus 6.0, and analysis by ANOVA and t test using SAS9.13. Results： The vertical l marginal gap in A group was 68.20±24.301xm, in B group was 46.31 ±23.43 μm and in C group was 60.58 ± 21.87 μm. All results were below 120μm. Significant differences were found among three groups （P= 0.0061）. There was no significant difference between A group and C group （P=0.2600）, and significant differences were found both between A group and B group （P=0.0027） and between B group and C group（P=0.0343）. Conclusion： Wax patterns fabricated by CAD/CAM had better marginal adaptation. High quality crown casting was obtained using a combination of wax patterns fabricated by a CAD/CAM system and a traditional casting method.