Objective:To investigate the effect of tooth preparation design on marginal fitting of CAD-CAM onlay.Methods:Two different methods were used for onlay preparation on two groups of resin teeth (10 teeth each group).Group 1 for the traditional way-MOD cavity,heavy chamfer on functional cusp,contrabevel on non-functional cusp.Group 2 is MOD cavity,"Butt joint" method,which has equal reduction on both functional and non-functional cusps.After preparation,the teeth were scanned with 3Shape intraoral scanner,and final restorations were fabricated with a milling machine.The fitness of the preparations and restorations was evaluated with Silicon replica technique.Results:The mean ± SD:0.1433mm±0.0158mm (Group 1),0.1821mm±0.0176mm (Group 2).These was a significant difference between two groups (P＜0.05),the silicon thickness for traditional preparation methods is less than that for the "Butt joint" method.Conclusion:Comparing to "Butt joint" preparation method,the traditional method has less influence on marginal fitting of CAD-CAM-Fabricated Onlay.%目的:研究高嵌体预备体形态设计与数字化制作边缘密合度是否相关.方法:采用两种不同方法在随机分组的20颗树脂牙上预备高嵌体,组1为传统方法“(牙合)面MOD洞+功能尖(牙合)台+非功能尖反斜面”预备,组2为“(牙合)面MOD洞+功能尖非功能尖平面均匀磨除”预备.使用3Shape口内扫描仪扫描预备体制作最终修复体,并使用间隙印模技术(Silicon replica)模拟粘接后,于同一标志点将模拟粘接剂的硅橡胶印模材料颊舌向一分为二,测量薄层硅橡胶的厚度,比较其区别.结果:Mean±SD:(组1)0.1433mm±0.0158mm,(组2)0.1821mm±0.0176mm,两组间硅橡胶平均厚度存在显著性差异(P＜0.05),传统型高嵌体牙体预备组硅橡胶平均厚度小于端端相接型高嵌体牙体预备组.结论:两种预备体形态对使用数字化制作出的最终修复体边缘密合度均在临床可接受范围内,传统型高嵌体牙体预备方式的数化制作高嵌体边缘密合度优于端端对接型牙体预备方式.
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