Department of Prosthodontics, University of Pittsburgh School of Dental Medicine, Pittsburgh, PA.
J Prosthodont. 2018 Jun;27(5):421-428. doi: 10.1111/jopr.12683. Epub 2017 Nov 16.
To evaluate the marginal fit of CAD/CAM copings milled from hybrid ceramic (Vita Enamic) blocks and lithium disilicate (IPS e.max CAD) blocks, and to evaluate the effect of crystallization firing on the marginal fit of lithium disilicate copings.
A standardized metal die with a 1-mm-wide shoulder finish line was imaged using the CEREC AC Bluecam. The coping was designed using CEREC 3 software. The design was used to fabricate 15 lithium disilicate and 15 hybrid ceramic copings. Design and milling were accomplished by one operator. The copings were seated on the metal die using a pressure clamp with a uniform pressure of 5.5 lbs. A Macroview Microscope (14×) was used for direct viewing of the marginal gap. Four areas were imaged on each coping (buccal, distal, lingual, mesial). Image analysis software was used to measure the marginal gaps in μm at 15 randomly selected points on each of the four surfaces. A total of 60 measurements were made per specimen. For lithium disilicate copings the measurements for marginal gap were made before and after crystallization firing. Data were analyzed using paired t-test and Kruskal-Wallis test.
The overall mean difference in marginal gap between the hybrid ceramic and crystallized lithium disilicate copings was statistically significant (p < 0.01). Greater mean marginal gaps were measured for crystallized lithium disilicate copings. The overall mean difference in marginal gap before and after firing (precrystallized and crystallized lithium disilicate copings) showed an average of 62 μm increase in marginal gap after firing. This difference was also significant (p < 0.01).
A significant difference exists in the marginal gap discrepancy when comparing hybrid ceramic and lithium disilicate CAD/CAM crowns. Also crystallization firing can result in a significant increase in the marginal gap of lithium disilicate CAD/CAM crowns.
评估 CAD/CAM 切削的混合陶瓷（ Vita Enamic）块和锂硅玻璃陶瓷（IPS e.max CAD）块制成的修复体边缘适合性，并评估结晶烧制对锂硅玻璃陶瓷修复体边缘适合性的影响。
使用 CEREC AC Bluecam 对具有 1mm 宽肩台线的标准化金属模具进行成像。使用 CEREC 3 软件设计修复体。使用该设计制作 15 个锂硅玻璃陶瓷和 15 个混合陶瓷修复体。设计和切削由一位操作员完成。使用压力夹将修复体置于金属模具上，压力均匀为 5.5 磅。使用 Macroview 显微镜（14×）直接观察边缘间隙。在每个修复体的四个区域（颊侧、远中侧、舌侧、近中侧）拍摄四个区域的图像。使用图像分析软件在每个表面的 15 个随机点测量边缘间隙的 μm 值。每个样本共进行 60 次测量。对于锂硅玻璃陶瓷修复体，在结晶烧制前后测量边缘间隙。使用配对 t 检验和 Kruskal-Wallis 检验分析数据。
混合陶瓷和结晶锂硅玻璃陶瓷修复体的边缘间隙总体平均值差异具有统计学意义（p < 0.01）。结晶锂硅玻璃陶瓷修复体的平均边缘间隙更大。结晶烧制前后（预结晶和结晶锂硅玻璃陶瓷修复体）的边缘间隙总体平均值差异显示，烧制后边缘间隙平均增加了 62μm。这种差异也具有统计学意义（p < 0.01）。
在比较混合陶瓷和锂硅玻璃陶瓷 CAD/CAM 冠时，边缘间隙差异存在显著差异。此外，结晶烧制会导致锂硅玻璃陶瓷 CAD/CAM 冠的边缘间隙显著增加。
