Zhou Yanan, Dong Xin, Li Ning, Yan Jiazhen
Lecturer, School of Mechanical Engineering, Shandong University of Technology, Zibo, PR China.
Graduate student, School of Mechanical Engineering, Sichuan University, Chengdu, PR China.
J Prosthet Dent. 2025 Jan;133(1):292-300. doi: 10.1016/j.prosdent.2023.01.030. Epub 2023 Mar 2.
The selective laser melting (SLM) technique has been a promising method of fabricating Co-Cr metal-ceramic restorations; however, the lower metal-ceramic bond properties of SLM Co-Cr restorations have become a major issue in clinical use.
The purpose of this in vitro study was to propose and verify a method of improving the metal-ceramic bond properties of SLM Co-Cr alloy with heat treatment after porcelain firing (PH).
Forty-eight (25×3×0.5 mm) Co-Cr specimens, divided into 6 groups (Control group [CG]; 550 °C; 650 °C; 750 °C; 850 °C; 950 °C) according to PH temperatures, were prepared by using SLM techniques. The 3-point bend tests were performed to evaluate the metal-ceramic bond strengths; subsequently, the fracture feature was assessed by using a digital camera and scanning electron microscope (SEM) coupled with an energy-dispersive X-ray spectroscopy (EDS) detector, to determine the area fraction of adherence porcelain (AFAP). The interface morphologies and element distribution were determined with SEM/EDS detectors. Phase identification and quantification were examined with an X-ray diffractometer (XRD). A 1-way ANOVA and the Tukey honestly significant difference tests were used to analyze bond strengths and AFAP values (α=.05).
The bond strengths were 35.33 ±1.25 MPa for the CG group, 34.53 ±3.20 MPa for the 550 °C group, 38.20 ±2.60 MPa for the 650 °C group, 42.85 ±2.31 MPa for the 750 °C group, 33.28 ±3.85 MPa for the 850 °C group, and 29.09 ±2.86 MPa for the 950 °C group. Significant differences were not observed among the CG, 550 °C, and 850 °C groups (P>.05) but were found among the other groups (P<.05). Fracture and AFAP results displayed a mixed fracture mode of adhesive and cohesive fracture. The thicknesses of native oxide films across the 6 groups were relatively close as the temperature increased, but the thickness of the diffusion layer increased as well. Excessive oxidation and massive phase transformation caused holes and microcracks to appear in the 850 °C and 950 °C groups, reducing bond strengths. XRD analysis evidenced that the phase transformation of γ→ε occurred at the interface during PH treating.
PH treatment significantly affected the metal-ceramic bond properties of SLM Co-Cr porcelain specimens. The 750 °C-PH-treated specimens displayed higher mean bond strengths and improved fracture characteristics among the 6 groups.
选择性激光熔化（SLM）技术一直是制造钴铬金属陶瓷修复体的一种有前景的方法；然而，SLM钴铬修复体较低的金属-陶瓷结合性能已成为临床应用中的一个主要问题。
本体外研究的目的是提出并验证一种通过瓷烧结后热处理（PH）改善SLM钴铬合金金属-陶瓷结合性能的方法。
采用SLM技术制备48个（25×3×0.5mm）钴铬试样，根据PH温度分为6组（对照组[CG]；550℃；650℃；750℃；850℃；950℃）。进行三点弯曲试验以评估金属-陶瓷结合强度；随后，使用数码相机和配备能量色散X射线光谱（EDS）探测器的扫描电子显微镜（SEM）评估断裂特征，以确定附着瓷的面积分数（AFAP）。用SEM/EDS探测器确定界面形态和元素分布。用X射线衍射仪（XRD）进行相鉴定和定量分析。采用单因素方差分析和Tukey真实显著性差异检验分析结合强度和AFAP值（α = 0.05）。
CG组的结合强度为35.33±1.25MPa，550℃组为34.53±3.20MPa，650℃组为38.20±2.60MPa，750℃组为42.85±2.31MPa，850℃组为33.28±3.85MPa，950℃组为29.09±2.86MPa。CG组、550℃组和850℃组之间未观察到显著差异（P>0.05），但其他组之间存在显著差异（P<0.05）。断裂和AFAP结果显示为粘结性和内聚性断裂的混合断裂模式。随着温度升高，6组原生氧化膜的厚度相对接近，但扩散层的厚度也增加。过度氧化和大量相变导致850℃和950℃组出现孔洞和微裂纹，降低了结合强度。XRD分析表明，在PH处理过程中，界面处发生了γ→ε的相变。
PH处理显著影响SLM钴铬瓷试样的金属-陶瓷结合性能。在6组中，750℃ PH处理的试样显示出更高的平均结合强度和改善的断裂特征。
