Assistant Professor, Department of Dental Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan, Republic of Korea.
Associate Professor, Department of Prosthodontics, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea.
J Prosthet Dent. 2022 Mar;127(3):489-496. doi: 10.1016/j.prosdent.2020.07.037. Epub 2020 Dec 7.
Although several manufacturers market soft metal milling blanks and systems, comprehensive comparative studies of differences in properties across commercially available soft metal milling alloys are lacking.
The purpose of this in vitro study was to compare the microstructures and mechanical properties of 3 soft metal milling cobalt-chromium (Co-Cr) alloys (Ceramill Sintron, Soft Metal, and Sintermetall).
Disk-shaped specimens (for surface characterization and hardness test) and dumbbell-shaped specimens (for tensile test as per International Organization for Standardization (ISO) 22674) were prepared by following each soft metal milling manufacturer's instructions. The crystal structures and microstructures of the 3 alloys were evaluated with optical microscopy, X-ray diffractometry (XRD), and scanning electron microscopy with electron backscattered diffraction (EBSD). The mechanical properties were investigated with a tensile test and Vickers hardness test (n=6). The results of the mechanical (tensile and hardness) tests were analyzed with 1-way ANOVA and the post hoc Tukey multiple comparison test (α=.05).
The Sintermetall specimen showed a finer microstructure and more porosity than the other 2 alloys. The XRD and EBSD analyses showed that the γ (face-centered cubic, fcc) matrix phase was predominant in the Ceramill Sintron alloy and the ε (hexagonal close-packed, hcp) matrix phase was predominant in the Soft Metal alloy. The Sintermetall alloy showed a slightly higher amount of ε phase than γ phase, with more chromium carbide formation than the other 2 alloys. The Ceramill Sintron alloy showed a significantly higher tensile strength than the other 2 alloys (P<.05), but a significantly lower 2% offset yield strength than the other 2 alloys (P<.05). The highest elongation was found in the Ceramill Sintron alloy, followed by the Sintermetall and Soft Metal alloys. The elastic modulus was the highest in the Sintermetall alloy, followed by the Soft Metal and Ceramill Sintron alloys. No significant differences in Vickers hardness values were detected among the 3 alloys (P=.263).
The different commercially available soft metal milling blanks and systems produced dissimilar alloys in terms of crystal structures and microstructures and, as a result, different mechanical properties.
尽管有几家制造商销售软金属铣削的坯料和系统，但缺乏对商业上可获得的软金属铣削合金性能差异的全面比较研究。
本体外研究的目的是比较三种软金属铣削钴铬（Co-Cr）合金（Ceramill Sintron、Soft Metal 和 Sintermetall）的微观结构和力学性能。
根据每个软金属铣削制造商的说明，制备圆盘状试件（用于表面特征和硬度测试）和哑铃状试件（用于按照国际标准化组织（ISO）22674 进行拉伸测试）。采用光学显微镜、X 射线衍射（XRD）和电子背散射衍射（EBSD）扫描电子显微镜对三种合金的晶体结构和微观结构进行评估。采用拉伸试验和维氏硬度试验（n=6）对力学性能进行研究。采用单因素方差分析和事后 Tukey 多重比较检验（α=.05）对力学（拉伸和硬度）试验的结果进行分析。
Sintermetall 试件的微观结构比其他两种合金更细，孔隙率更高。XRD 和 EBSD 分析表明，Ceramill Sintron 合金中的γ（面心立方，fcc）基体相占主导地位，Soft Metal 合金中的ε（六方密排，hcp）基体相占主导地位。Sintermetall 合金中ε 相的含量略高于γ 相，且比其他两种合金形成更多的铬碳化物。Ceramill Sintron 合金的拉伸强度明显高于其他两种合金（P<.05），但 2%屈服强度明显低于其他两种合金（P<.05）。Ceramill Sintron 合金的伸长率最高，其次是 Sintermetall 和 Soft Metal 合金。弹性模量在 Sintermetall 合金中最高，其次是 Soft Metal 和 Ceramill Sintron 合金。三种合金的维氏硬度值无显著差异（P=.263）。
不同商业上可获得的软金属铣削坯料和系统在晶体结构和微观结构方面产生了不同的合金，因此具有不同的力学性能。
