Htat Hein Linn, Limpuangthip Nareudee, Lee Jae-Hyun, Lee Sang J
Department of Prosthodontics, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Department of Prosthodontics, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
J Dent. 2025 Sep;160:105856. doi: 10.1016/j.jdent.2025.105856. Epub 2025 May 27.
To investigate the effects of different printing orientations and heat treatment temperatures on the fit and hardness of cobalt-chromium (Co-Cr) crowns fabricated using selective laser melting (SLM) technology.
SLM Co-Cr crowns were printed at 0°, 45°, and 90° orientations and subjected to heat treatment at 750 °C, 980 °C, 1150 °C, or none (n = 10 per group). The silicone replica technique was used to assess marginal and internal gaps at 20 measurement points across five areas: occlusal, axial wall, axio-occlusal, cervical, and marginal gaps (MGs). Vickers hardness was assessed at the occlusal surface of crowns. Statistical analyses included two-way ANOVA (α=0.05).
Crowns printed at a 90° orientation exhibited significantly larger marginal and internal gaps than those printed at 0° or 45° orientation, regardless of heat treatment temperature (p < 0.001). Occlusal region showed the largest discrepancies, while axial walls exhibited the smallest. Clinically acceptable MGs (<120 µm) were observed in crowns printed at a 0° orientation without heat treatment and at 0° or 45° with heat treatment at 1150 °C. Crowns treated at 1150 °C demonstrated the lowest hardness values, while those treated at 750 °C or at 980 °C showed significantly higher hardness but larger, clinically unacceptable MGs at certain locations (p < 0.05).
Printing orientation and heat treatment significantly influenced both fit and hardness of SLM Co-Cr crowns. A 0° printing orientation without post-printing heat treatment, and 0° or 45° with heat treatment at 1150 °C, are preferable for fabricating SLM Co-Cr crowns to achieve favorable fit and hardness.
When single cobalt-chromium crowns are fabricated using selective laser melting technology, a 0° printing orientation without heat treatment, and 0° or 45° orientation with heat treatment at 1150 °C, are considered to achieve acceptable marginal fit, internal adaptation, and appropriate hardness. A 90° orientation may lead to increased marginal gaps.
探讨不同打印方向和热处理温度对采用选择性激光熔化（SLM）技术制作的钴铬（Co-Cr）冠的贴合度和硬度的影响。
将SLM Co-Cr冠分别以0°、45°和90°方向打印，并在750℃、980℃、1150℃进行热处理，或不进行热处理（每组n = 10）。采用硅橡胶复制技术评估五个区域（咬合面、轴壁、轴-咬合面、颈部和边缘间隙（MG））的20个测量点处的边缘和内部间隙。在冠的咬合面评估维氏硬度。统计分析采用双向方差分析（α = 0.05）。
无论热处理温度如何，90°方向打印的冠的边缘和内部间隙均显著大于0°或45°方向打印的冠（p < 0.001）。咬合区域差异最大，而轴壁差异最小。在未进行热处理的0°方向打印的冠以及在1150℃进行热处理的0°或45°方向打印的冠中观察到临床可接受的MG（<120μm）。在1150℃处理的冠显示出最低的硬度值，而在750℃或980℃处理的冠显示出显著更高的硬度，但在某些位置有更大的、临床不可接受的MG（p < 0.05）。
打印方向和热处理显著影响SLM Co-Cr冠的贴合度和硬度。对于制作SLM Co-Cr冠以获得良好的贴合度和硬度，不进行打印后热处理的0°打印方向以及在1150℃进行热处理的0°或45°方向是优选的。
当使用选择性激光熔化技术制作单个钴铬冠时，不进行热处理的0°打印方向以及在1150℃进行热处理的0°或45°方向被认为可实现可接受的边缘贴合、内部适应性和适当的硬度。90°方向可能导致边缘间隙增加。
