Graduate student, Dental Materials Laboratory and Department of Prosthodontics, Peking University School of Stomatology, Beijing, PR China.
Assistant Professor, Dental Materials Laboratory, Peking University School of Stomatology, Beijing, PR China.
J Prosthet Dent. 2018 Aug;120(2):319.e1-319.e6. doi: 10.1016/j.prosdent.2018.05.012.
Components fabricated by selective laser melting (SLM) deform because of residual stress, but heat treatment allows the release of that stress and avoids deformation. Although dental cobalt-chromium (Co-Cr) alloy has been specifically designed for SLM, the effects of heat treatment on the metal-ceramic combination of SLM Co-Cr restorations require investigation.
The purpose of this in vitro study was to evaluate the effects of heat treatment on the metal-ceramic combination of SLM Co-Cr alloy.
Following ISO 9693:2012, Co-Cr metal strips (Solibond C Plus cast alloy and SLM powders; YETI Dental) were fabricated with a dimension of 25×3×0.5 mm by casting and SLM. The SLM specimens were divided into 3 subgroups (n=15 for each subgroup). Two subgroups were subjected to heat treatment at 880°C (SLM-880) and 1100°C (SLM-1100). The third subgroup was not subjected to heat treatment and served as a control (As-SLM). Cast specimens (n=15) also acted as a control. A porcelain layer with a thickness of 1.1 mm was fired to the central area (3×8 mm) of each specimen. The 3-point bend test was used to evaluate the metal-ceramic bond strength (τ). The fractured metal surfaces were examined by the naked eye, using a digital camera, and also using a scanning electron microscope. The area fraction of adherence porcelain (AFAP) was determined by measuring the atomic percentage of silicon using energy-dispersive x-ray spectroscopy (EDS). One-way ANOVA and the Kruskal-Wallis test, followed by the Mann-Whitney test (α=.05), were used for statistical analysis.
The 1-way ANOVA found no significant difference in the bond strength among the 4 groups. The EDS analysis indicated that specimens in the groups receiving heat treatment (SLM-880 and SLM-1100) showed higher AFAP values than those in the As-SLM group (P<.05). The SLM-880 also showed significantly higher AFAP values than the SLM-1100. Compared with the cast group, significant differences in AFAP values were also observed, and the specimens in the order of highest to lowest AFAP values were SLM-880>cast>As-SLM; no significant difference was found between the SLM-1100 and cast groups.
Heat treatment at 880°C and 1100°C did not affect the metal-ceramic bond strength of Co-Cr alloy made by SLM but did improve the porcelain adherence. SLM-fabricated and heat-treated Co-Cr alloy shows comparable or more porcelain adherence than cast specimens.
选择性激光熔化（SLM）制造的部件会因残余应力而变形，但热处理可以释放这些应力并避免变形。尽管牙科钴铬（Co-Cr）合金是专门为 SLM 设计的，但热处理对 SLM Co-Cr 修复体的金属-陶瓷组合的影响仍需要研究。
本体外研究的目的是评估热处理对 SLM Co-Cr 合金的金属-陶瓷结合的影响。
根据 ISO 9693:2012，通过铸造和 SLM 制造尺寸为 25×3×0.5mm 的 Co-Cr 金属带（Solibond C Plus 铸造合金和 SLM 粉末；YETI Dental）。将 SLM 试样分为 3 组（每组 15 个试样）。两组试样在 880°C（SLM-880）和 1100°C（SLM-1100）下进行热处理。第三组不进行热处理，作为对照（As-SLM）。铸造试样（n=15）也作为对照。在每个试样的中心区域（3×8mm）烧制厚度为 1.1mm 的瓷层。使用三点弯曲试验评估金属-陶瓷结合强度（τ）。使用数码相机和扫描电子显微镜肉眼检查断裂的金属表面。通过能谱仪（EDS）测量硅的原子百分比来确定附着瓷的面积分数（AFAP）。使用单因素方差分析和 Kruskal-Wallis 检验，然后使用曼-惠特尼检验（α=.05）进行统计学分析。
单因素方差分析发现 4 组间结合强度无显著差异。EDS 分析表明，接受热处理的组（SLM-880 和 SLM-1100）的试样的 AFAP 值高于 As-SLM 组（P<.05）。SLM-880 的 AFAP 值也明显高于 SLM-1100。与铸造组相比，AFAP 值也存在显著差异，AFAP 值从高到低的顺序为 SLM-880>铸造>As-SLM；SLM-1100 与铸造组之间无显著差异。
880°C 和 1100°C 的热处理并未影响 SLM 制造的 Co-Cr 合金的金属-陶瓷结合强度，但改善了瓷的附着性。SLM 制造并经热处理的 Co-Cr 合金显示出与铸造试样相当或更高的瓷附着性。
