Dental Laboratory Technician, 4RD Dental Laboratory, Seoul, Republic of Korea.
J Prosthet Dent. 2022 Sep;128(3):415-420. doi: 10.1016/j.prosdent.2020.08.029. Epub 2021 Feb 11.
Information on the fabrication of metal by selective laser melting (SLM) systems positioned at different angles is sparse.
The purpose of this in vitro study was to evaluate the extent of marginal and internal gaps in metal copings fabricated at different angles by using an SLM fabrication system.
A master metal model was produced and replicated (N=10) with silicone impressions and dental stone. Standard tessellation language (STL) files of the 10 coping designs were then obtained by using a model scanner and a 3D design software program on a scannable working die. Co-Cr alloy metal copings were fabricated by the SLM fabrication system at 45, 90, and 180 degrees. The marginal and internal gaps were measured by the silicone replica technique. The measured data were analyzed by using the nonparametric Kruskal-Wallis H test (α=.05).
The specimens fabricated at 180 degrees showed the best fit in terms of the marginal gap, while the worst fit was observed in the specimens fabricated at 90 degrees. Statistically significant differences were seen among the marginal gaps produced in the 3 groups (P<.001). In terms of internal fit, the axial wall gap showed the best fit, and the occlusal gap the worst. The best fit overall was 66 μm at the axial wall of the 180-degree group, and the worst in the 90-degree group, at 663 μm. Statistically significant differences were observed between the chamfers, axial walls, and the occlusal gaps of the 3 groups (P<.001).
Restorations fabricated by using an SLM system at 180 degrees were clinically acceptable. However, more research is required to investigate the performance of metal copings produced at 45 and 90 degrees to evaluate their clinical acceptability.
关于在不同角度定位的选择性激光熔化（SLM）系统制造金属的信息很少。
本体外研究的目的是评估使用 SLM 制造系统在不同角度制造的金属冠的边缘和内部间隙的程度。
制作并复制（N=10）了一个金属模型，使用硅橡胶印模和牙科石膏。然后通过模型扫描仪和可扫描工作模具上的 3D 设计软件程序获得 10 个冠设计的标准网格语言（STL）文件。通过 SLM 制造系统在 45、90 和 180 度的角度制造 Co-Cr 合金金属冠。通过硅橡胶复制技术测量边缘和内部间隙。使用非参数 Kruskal-Wallis H 检验（α=.05）分析测量数据。
在边缘间隙方面，180 度制造的试件具有最佳的拟合度，而 90 度制造的试件则表现出最差的拟合度。3 组之间的边缘间隙差异有统计学意义（P<.001）。在内部拟合方面，轴向壁间隙具有最佳的拟合度，而牙合间隙则最差。总体而言，180 度组的轴向壁间隙的最佳拟合度为 66μm，90 度组的最差拟合度为 663μm。3 组之间的斜角、轴向壁和牙合间隙存在统计学显著差异（P<.001）。
使用 SLM 系统在 180 度制造的修复体在临床是可接受的。然而，需要进一步研究来评估在 45 和 90 度制造的金属冠的性能，以评估其临床可接受性。
