Department of Prosthodontics, Faculty of Dentistry, Jordan University of Science and Technology (JUST), Irbid, Jordan.
Advanced Specialty Education Program in Prosthodontics, Loma Linda University, School of Dentistry, Loma Linda, CA.
J Prosthodont. 2020 Apr;29(4):341-349. doi: 10.1111/jopr.12926. Epub 2018 Jun 13.
The introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) technology to the field of removable prosthodontics has recently made it possible to fabricate complete dentures of prepolymerized polymethyl methacrylate (PMMA) blocks, which are claimed to be of better mechanical properties; however, no published reports that have evaluated mechanical properties of CAD/CAM PMMA. The purpose of this study was to compare flexural strength, impact strength, and flexural modulus of two brands of CAD/CAM PMMA and a conventional heat-cured PMMA.
45 rectangular specimens (65 mm × 10 mm × 3 mm) were fabricated (15 CAD/CAM AvaDent PMMA specimens from AvaDent, 15 CAD/CAM Tizian PMMA specimens from Shütz Dental, 15 conventional Meliodent PMMA specimens from Heraeus Kulzer) and stored in distilled water at (37 ± 1°C) for 7 days. Specimens (N = 15) in each group were subjected to the three-point bending test and impact strength test, employing the Charpy configuration on unnotched specimens. The morphology of the fractured specimens was studied under a scanning electron microscope (SEM). Statistical analysis was performed using one-way ANOVA and Tukey pairwise multiple comparisons with 95% confidence interval.
The Schütz Dental specimens showed the highest mean flexural strength (130.67 MPa) and impact strength (29.56 kg/m ). The highest mean flexural modulus was recorded in the AvaDent group (2519.6 MPa). The conventional heat-cured group showed the lowest mean flexural strength (93.33 MPa), impact strength (14.756 kg/m ), and flexural modulus (2117.2 MPa). Differences in means of flexural properties between AvaDent and Schütz Dental specimens were not statistically significant (p > 0.05).
As CAD/CAM PMMA specimens exhibited improved flexural strength, flexural modulus, and impact strength in comparison to the conventional heat-cured groups, CAD/CAM dentures are expected to be more durable. Different brands of CAD/CAM PMMA may have inherent variations in mechanical properties.
计算机辅助设计/计算机辅助制造（CAD/CAM）技术在可摘义齿领域的引入使得预制聚甲基丙烯酸甲酯（PMMA）块的全口义齿的制作成为可能，据称其具有更好的机械性能；然而，目前尚无研究评估 CAD/CAM PMMA 的机械性能。本研究的目的是比较两种品牌的 CAD/CAM PMMA 与传统热固化 PMMA 的弯曲强度、冲击强度和弯曲模量。
制作 45 个矩形试件（65mm×10mm×3mm）（AvaDent 品牌的 15 个 CAD/CAM AvaDent PMMA 试件、Shütz Dental 品牌的 15 个 CAD/CAM Tizian PMMA 试件、Heraeus Kulzer 品牌的 15 个传统 Meliodent PMMA 试件），并在（37±1°C）蒸馏水中储存 7 天。每组中的 15 个试件（N=15）均采用无缺口夏比配置在三点弯曲试验机和冲击强度试验机上进行测试。用扫描电子显微镜（SEM）观察断裂试件的形态。使用单因素方差分析和 Tukey 多重比较进行统计分析，置信区间为 95%。
Schütz Dental 试件的平均弯曲强度（130.67 MPa）和冲击强度（29.56 kg/m）最高。AvaDent 组的平均弯曲模量最高（2519.6 MPa）。传统热固化组的平均弯曲强度（93.33 MPa）、冲击强度（14.756 kg/m）和弯曲模量（2117.2 MPa）最低。AvaDent 和 Schütz Dental 试件的弯曲性能平均值之间无统计学差异（p＞0.05）。
与传统热固化组相比，CAD/CAM PMMA 试件的弯曲强度、弯曲模量和冲击强度均有所提高，因此预计 CAD/CAM 义齿更耐用。不同品牌的 CAD/CAM PMMA 可能具有固有机械性能差异。
