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），评估两种设置不同粘接间隙的计算机辅助设计/计算机辅助制造（CAD/CAM）材料的咬合贴面修复适配性。本研究共制备60个树脂代型，按修复材料分为两组（n=30）：组I为混合全瓷材料，组II为氧化锆增强硅酸锂玻璃陶瓷（zirconia-reinforced lithium silicate glass-ceramic）。每组再依据粘接间隙参数（30、40、50 µm）划分为3个亚组（n=10）。为上述6个亚组制备咬合贴面并完成铣削加工。在每个扫描样本的中心区域放置一个包含20个分区的圆形标记，用于测量四个位置的间隙参数：咬合侧间隙、轴侧间隙、边缘间隙以及绝对边缘偏差。采用双因素方差分析（two-way ANOVA）在0.05的显著性水平下对实验数据进行统计分析。结果显示：在三种粘接间隙参数下，材料类型对内部间隙与边缘间隙的均值无统计学显著影响（P>0.05）。不同粘接间隙参数下，咬合间隙与轴侧间隙均未表现出统计学显著差异；但边缘间隙距离与绝对边缘偏差存在统计学显著差异（P>0.05）。混合全瓷材料的边缘与内部偏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，50 µm的粘接间隙均可显著改善边缘适配性与绝对边缘偏差。