基牙尖锐边缘嵴对铸造冠适合性的影响

Sharp marginal ridge affects the fitness of the metal full crown cast for the abutment tooth

目的:研究牙体制备过程中基牙尖锐边缘嵴对铸造冠适合性的影响。方法:在已设计好的具有尖锐边缘嵴和圆钝边缘嵴的NO.2试验体(ADA)模型上分别制作铸造全冠,并进行分组试验。将轻体硅橡胶注入铸造全冠内后立即戴在各组模型上,待其凝固后测量各组模型与全冠之间的硅橡胶厚度。厚度越小,铸造冠适合性越好。结果:在圆钝边缘嵴模型组测得硅橡胶厚度的平均值为250μm,在尖锐边缘嵴模型组测得硅橡胶厚度的平均值为1 660μm,两者之间差异有显著性统计学意义(P<0.01)。结论:与尖锐边缘嵴相比较,圆钝边缘嵴模型制备出的铸造冠具有更加良好的适合性。

Objective： To study the effect of the sharp marginal ridge of the abutment on the casting of the fit metal full crown in dental preparation. Methods： We established the models of the designed crown-based-teeth （American Dental Association style, No2 trail） with a sharp or smooth marginal ridge, and cast a metal crown for each model. We injected silicone into the crown and immediately fixed it onto each model. Then we took out the solidified silicone and measured its thickness between the crown and the occlusal face of each model. The thinner the thickness, the better the fitness. Results ： The average silicone thickness was 250 μm in the smooth marginal ridge group and 1 660 μm in the sharp marginal ridge group, with significant difference in between （ P 〈 0.01 ）. Conclusion ： Better fitness can be achieved in casting the metal full crown on a smooth marginal ridge than on a sharp one.