Department of Prosthodontics, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, China.
Shanghai Xuhui District Dental Center, Shanghai, China.
J Prosthodont Res. 2022 Jul 30;66(3):459-465. doi: 10.2186/jpr.JPR_D_21_00017. Epub 2021 Oct 6.
Evaluating the fitness accuracy and retentive force of cobalt-chrome (Co-Cr) alloy clasps fabricated using the selective laser melting (SLM) technique.
Premolar and molar abutment models with a 0.5-mm undercut depth, 1.5-mm-thick occlusal rest seats, and guiding planes were designed and fabricated using a milling machine. On these models, Akers clasps with 0.25- and 0.5-mm undercut depths were designed and fabricated with SLM and a traditional lost wax casting method. Based on the manufacturing methods, abutment types, and undercut depths, the clasps were divided into eight groups (10 per group). The fitness accuracy of the clasps was evaluated by measuring the gap distance between the clasps and abutments using a silicone film method. The initial retentive force and changes in retention up to 7,200 insertion/removal cycles of the clasps were also measured. The data were analyzed using multiple linear regression, paired t-tests, and one-way ANOVA (α=0.05).
For both the SLM and cast clasps, the fitness accuracy of the rest was greater than that of the clasp tip and shoulder. No significant difference was found in the fitness accuracy between the SLM and cast clasps, regardless of the abutment type and undercut depth before or after insertion/removal cycles (p>0.05). There was also no significant difference in the initial retentive force between the SLM and cast clasps (p>0.05). After 7,200 insertion/removal cycles, the SLM clasp exhibited a greater residual retentive force (p<0.05).
The SLM technique for manufacturing the clasps of removable partial dentures has promising clinical applications.
评估使用选择性激光熔化（SLM）技术制造的钴铬（Co-Cr）合金卡环的适配精度和固位力。
使用铣床设计并制作具有 0.5mm 底切深度、1.5mm 厚的咬合支托凹和导向面的前磨牙和磨牙基牙模型。在这些模型上，使用 SLM 和传统失蜡铸造法设计并制作了具有 0.25mm 和 0.5mm 底切深度的 Akers 卡环。根据制造方法、基牙类型和底切深度，将卡环分为八组（每组 10 个）。使用硅橡胶膜法测量卡环与基牙之间的间隙距离来评估卡环的适配精度。还测量了卡环的初始固位力以及在插入/取出循环 7200 次前后的保持力变化。使用多元线性回归、配对 t 检验和单因素方差分析（α=0.05）对数据进行分析。
对于 SLM 和铸造卡环，支托的适配精度均大于卡环尖端和肩部的适配精度。在插入/取出循环前后，无论基牙类型和底切深度如何，SLM 和铸造卡环的适配精度均无显著差异（p>0.05）。SLM 和铸造卡环的初始固位力也无显著差异（p>0.05）。经过 7200 次插入/取出循环后，SLM 卡环表现出更大的残余固位力（p<0.05）。
使用 SLM 技术制造可摘局部义齿卡环具有良好的临床应用前景。
