Department of Oral and Maxillofacial Prosthodontics, Faculty of Dentistry, British University in Egypt, Cairo, Egypt.
Department of Oral and Maxillofacial Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
J Prosthodont. 2024 Oct;33(8):801-807. doi: 10.1111/jopr.13765. Epub 2023 Sep 25.
To evaluate the overall adaptation and retention of class I cobalt-chromium (Co-Cr) removable partial denture (RPD) frameworks using three different computer-aided design and computer-aided manufacturing (CAD-CAM) technologies: Indirect wax milling with lost wax technique (LWT), direct milling, and selective laser melting (SLM) technique.
An educational maxillary stone model (Kennedy class I) was scanned after preparing rest seats to create a resin model. The resin model was scanned, and the RPD framework was digitally designed and saved as a standard tessellation language (STL) file. Twenty-four Co-Cr RPD frameworks were then constructed and divided into three groups (n = 8) based on fabrication technique: Group A (indirect wax milling with LWT), Group B (direct milling), and Group C (selective laser melting). In Group A, the STL file was used to mill the design from castable resin blanks which were then cast by the LWT. In Group B, the STL file was used to mill the design from the Co-Cr blank directly. Finally in Group C, the STL file was used to print the design from Co-Cr powder using SLM 3D printed technique. Geomagic Control X software was used to measure the overall adaptation of the fabricated RPD frameworks, Retention was also tested using a universal testing machine. One-way Analysis of Variance (ANOVA) test was used to compare the three groups then the Tukey HSD post-hoc test was used for pair-wise comparisons. The significance level was set at p ≤ 0.05.
Regarding the overall adaptation, Group B (0.71 ± 0.02 mm) showed significantly higher adaptation than Group A (0.96 ± 0.06 mm) and Group C (1.05 ± 0.16 mm). Regarding retention, Group B (2.03 ± 0.34 N) showed significantly higher retention than Group A (1.00 ± 0.13 N) and Group C (0.78 ±0.17 N).
Based on the findings of this in vitro study, Co-Cr RPD frameworks fabricated by direct milling technique revealed the best adaptation and retention.
使用三种不同的计算机辅助设计和计算机辅助制造 (CAD-CAM) 技术评估 I 类钴铬 (Co-Cr) 可摘局部义齿 (RPD) 架的整体适应性和保持力：间接失蜡法蜡模铸造 (LWT)、直接铣削和选择性激光熔化 (SLM) 技术。
在制备休息区后，对教育上颌石模型 (Kennedy 第一类) 进行扫描，以创建树脂模型。扫描树脂模型，数字化设计 RPD 架并保存为标准三角测量语言 (STL) 文件。然后构建 24 个 Co-Cr RPD 架，并根据制造技术将其分为三组 (n = 8)：A 组 (间接失蜡法蜡模铸造)、B 组 (直接铣削) 和 C 组 (选择性激光熔化)。在 A 组中，使用 STL 文件从可铸造树脂毛坯中铣削设计，然后通过 LWT 浇铸。在 B 组中，使用 STL 文件直接从 Co-Cr 毛坯中铣削设计。最后在 C 组中，使用 SLM 3D 打印技术从 Co-Cr 粉末打印设计。Geomagic Control X 软件用于测量制造的 RPD 架的整体适应性，使用万能试验机测试保持力。使用单向方差分析 (ANOVA) 检验比较三组，然后使用 Tukey HSD 事后检验进行两两比较。显著性水平设为 p ≤ 0.05。
就整体适应性而言，B 组 (0.71 ± 0.02mm) 显示出明显高于 A 组 (0.96 ± 0.06mm) 和 C 组 (1.05 ± 0.16mm) 的适应性。就保持力而言，B 组 (2.03 ± 0.34N) 显示出明显高于 A 组 (1.00 ± 0.13N) 和 C 组 (0.78 ± 0.17N) 的保持力。
根据本体外研究的结果，直接铣削技术制造的 Co-Cr RPD 架显示出最佳的适应性和保持力。
