Chief of Clinical Services, Prosthodontics Department, School of Dentistry, Lebanese University, Hadath, Lebanon.
Professor, Dental Materials Unit, University of Zurich, Zürich, Switzerland.
J Prosthet Dent. 2018 May;119(5):783-790. doi: 10.1016/j.prosdent.2017.07.025. Epub 2017 Sep 29.
The subtractive and additive computer-aided design and computer-aided manufacturing (CAD-CAM) of lithium disilicate partial coverage restorations is poorly documented.
The purpose of this in vitro study was to compare the marginal and internal fit accuracy of lithium disilicate glass-ceramic inlays fabricated with conventional, milled, and 3-dimensional (3D) printed wax patterns.
A dentoform mandibular first molar was prepared for a mesio-occlusal ceramic inlay. Five groups of 15 inlays were obtained through conventional impression and manual wax pattern (group CICW); conventional impression, laboratory scanning of the stone die, CAD-CAM milled wax blanks (group CIDW) or 3D printed wax patterns (group CI3DW); and scanning of the master preparation with intraoral scanner and CAD-CAM milled (group DSDW) or 3D printed wax patterns (group DS3DW). The same design was used to produce the wax patterns in the last 4 groups. The replica technique was used to measure marginal and internal adaptation by using stereomicroscopy. Mixed-model ANOVA was used to assess differences according to the groups and discrepancy location (α=.05).
Group DSDW showed the smallest marginal discrepancy (24.3 μm) compared with those of groups CICW (45.1 μm), CIDW (33.7 μm), CI3DW (39.8 μm), and DS3DW (39.7 μm) (P<.001). No statistically significant differences were detected among groups CICW, CIDW, CI3DW, and DS3DW relative to the marginal discrepancy. The internal discrepancy was significantly larger than the marginal discrepancy within all groups (P<.001).
Lithium disilicate glass-ceramic inlays produced from digital scans and subtractive milling of wax patterns resulted in better marginal and internal fit accuracy than either conventional impression/fabrication or additive 3D manufacturing. Three-dimensional printed wax patterns yielded fit values similar to those of the conventionally waxed inlays.
关于使用减法和加法计算机辅助设计和计算机辅助制造（CAD-CAM）来制作二硅酸锂局部覆盖修复体的文献记载很少。
本体外研究的目的是比较使用传统、铣削和 3 维（3D）打印蜡模制作的二硅酸锂玻璃陶瓷嵌体的边缘和内部适合精度。
制备下颌第一磨牙的近中-远中面陶瓷嵌体。通过传统印模和手动蜡型（组 CICW）；传统印模、石模的实验室扫描、CAD-CAM 铣削蜡坯（组 CIDW）或 3D 打印蜡型（组 CI3DW）；以及口内扫描仪扫描的主预备体和 CAD-CAM 铣削（组 DSDW）或 3D 打印蜡型（组 DS3DW）获得了 5 组每组 15 个嵌体。最后 4 组使用相同的设计制作蜡型。使用立体显微镜通过复制技术测量边缘和内部适应性。根据组和差异位置使用混合模型方差分析评估差异（α=.05）。
与 CICW 组（45.1μm）、CIDW 组（33.7μm）、CI3DW 组（39.8μm）和 DS3DW 组（39.7μm）相比，DSDW 组的边缘差异最小（24.3μm）（P<.001）。CICW、CIDW、CI3DW 和 DS3DW 组之间的边缘差异无统计学差异。与边缘差异相比，所有组的内部差异均显著较大（P<.001）。
与传统印模/制作或加法 3D 制造相比，从数字扫描和蜡模减法铣削制作的二硅酸锂玻璃陶瓷嵌体具有更好的边缘和内部适合精度。3D 打印蜡模的拟合值与传统蜡模嵌体相似。
