烧结次数对椅旁计算机辅助设计与制作二硅酸锂玻璃陶瓷贴面不同部位颜色的影响

目的 评价烧结次数和渐变厚度及其交互性对椅旁计算机辅助设计与制作（CAD/CAM）二硅酸锂玻璃陶瓷贴面不同部位颜色的影响。方法 在标准中切牙模型上制备贴面修复模型,用椅旁扫描仪采集光学印模,椅旁CAD/CAM系统制作24个二硅酸锂玻璃陶瓷贴面样本共4组（n=6）,初次结晶组为对照组S0,其余按上釉烧结次数依次为S1、S2、S3组。使用Vita easyshade电子比色仪测定每个贴面的色彩参数L、C、H、a、b,用SAS 9.1.3统计软件采用重复测量多因素方差方法分析不同烧结次数以及不同部位厚度间各颜色指标的差异性。最后扫描电镜（SEM）观察每组贴面的晶体排列和致密度。结果 随着烧结次数增加,试件的L值总体呈减小趋势（P<0.05）。C和b的烧结次数有统计学意义（P<0.05）,其中,除S2组与S3组之间差异无统计学意义外（P>0.05）,其余各组之间的两两比较差异均有统计学意义（P<0.05）。SEM观察发现二硅酸锂晶体随着烧结次数增加,晶体变大,晶体间的孔隙变小,晶体间的锁结变得更为紧密。结论 上釉次数和厚度及其交互性对二硅酸锂玻璃陶瓷的色相、明度、彩度均存在影响。

Effect of repeated sintering and variations in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers

Objective The aim of this study is to evaluate the effect of repeated sintering and variation in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers. Methods A total of 24 computer aided design and computer aided manufacturing (CAD/CAM) veneers was fabricated using the IPS e.max-CAD LS2 and then randomly divided into four groups (S0, S1, S2, S3; n=6). Each group was sintered 0, 1, 2, 3 times individually according to the manufacturer's recommendation. The color parameters (L, C, H, a, b values) of all the specimens were measured by a Vita easyshade dental colorimeter. The results were statistically analyzed using the SAS 9.1.3 software for MANOVA and LSD. Subsequently, the microstructures of the intersecting surfaces of the specimens were observed by scanning electron microscopy (SEM). Results After repeated sintering, the L value significantly decreased (P<0.05). For the C and b values, statistical differences were observed among the groups except between S2 and S3. SEM results showed that the interlocking microstructures of rod-shaped Li2Si2O5 crystals became more compact when the number of sintering times was increased. Conclusion Repeated sintering exhibited significant influence on the color of the IPS e.max-CAD LS2 veneers.