MicroCT evaluation for CAD/CAM occlusal veneer fit using two materials and three cement space settings

Abstract This study was aimed to evaluate the fit of occlusal veneer restoration for two CAD/CAM materials with different cement space settings, using microCT scans. Sixty resin dies were made and divided into two groups (n=30) according to the materials, (I): Hybrid all-ceramic, and (II): zirconia-reinforced lithium silicate glass-ceramic. Each group was subdivided into three subgroups (n=10) according to the cement space parameters (30, 40, and 50 µm). Occlusal veneers for the six subgroups were milled. A circle with 20 different sections was placed at the center of every scanned specimen to measure four different locations (Occlusal, Axial, Marginal, and Absolute marginal discrepancy). Data were analyzed using two-way ANOVA at a 0.05 level of significance. There was no statistically significant effect of material type on the mean values of internal and marginal gaps for the three cement space parameters (P>0.05). There were no statistically significant differences in the occlusal and axial gap between the cement space parameters, furthermore, there were statistically significant differences in marginal gap distances and absolute marginal discrepancies (P>0.05). Hybrid all-ceramic showed smaller marginal and internal discrepancies than zirconia-reinforced lithium silicate glass-ceramic without statistically significant differences, and, for both materials, 50 µm cement space significantly improved the marginal fit and absolute marginal discrepancy.

摘要 本研究旨在通过显微计算机断层扫描（microCT），评估两种采用不同粘接间隙（cement space）参数的计算机辅助设计与计算机辅助制造（CAD/CAM）材料用于咬合贴面修复（occlusal veneer restoration）时的适配性能。共制备60颗树脂代型（resin dies），按修复材料分为两组（每组n=30）：组I为混合全瓷材料（Hybrid all-ceramic），组II为氧化锆增强硅酸锂玻璃陶瓷（zirconia-reinforced lithium silicate glass-ceramic）。每组再根据粘接间隙参数（30、40、50 μm）划分为3个亚组（每组n=10），随后为6个亚组的试件铣削制备咬合贴面。在每一个扫描试件的中心设置带有20个不同分区的圆形区域，用于测量四个不同位置的间隙参数：咬合间隙、轴面间隙、边缘间隙以及绝对边缘间隙差。采用双因素方差分析（two-way ANOVA）对数据进行分析，检验水准设定为0.05。结果显示，针对三种粘接间隙参数，材料类型对内部间隙与边缘间隙的均值无统计学显著性影响（P>0.05）。不同粘接间隙参数下，咬合间隙与轴面间隙均无统计学显著性差异；而边缘间隙距离与绝对边缘间隙差则存在统计学显著性差异（P>0.05）。混合全瓷材料的边缘与内部间隙差均小于氧化锆增强硅酸锂玻璃陶瓷，但该差异无统计学显著性；且对于两种材料而言，采用50 μm粘接间隙均可显著改善其边缘适配性与绝对边缘间隙差。