Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Plattenstrasse 11, 8032, Zurich, Switzerland.
Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece.
Prog Orthod. 2022 Feb 21;23(1):6. doi: 10.1186/s40510-022-00400-z.
Three-dimensional (3D) printing technology is an emerging manufacturing process for many orthodontic appliances, and the aim of this study was to evaluate the mechanical properties of resin-based materials as alternatives for the in-house preparation of orthodontic brackets.
Two types of 3D printed resins used for temporary (T) and permanent (P) crown fabrication were included in this study. Ten blocks from each resin were manufactured by a 3D printer and, after embedding them in acrylic resin, the samples were subjected to metallographic grinding and polishing, followed by instrumented indentation testing (IIT). Martens hardness (HM), indentation modulus (E), and elastic index (η) were determined with a Vickers indenter recording force-indentation depth curves from each specimen. After calculating descriptive statistics, differences between material types were investigated with Wilcoxon rank sum test accounting for clustering of measurements within specimens at alpha = 5%.
No statistically significant differences in the mechanical properties of the two tested materials were seen: HM: median 279 N/mm (interquartile range [IQR] 275-287 N/mm) for T and median 279 N/mm (IQR 270-285 N/mm) for P (P value = 0.63); E: median 5548 MPa (IQR 5425-5834 MPa) for T and median 5644 (IQR 5420-5850 MPa) for P (P value = 0.84); η: median 47.1% (46.0-47.7%) for T and median 46.0% (IQR 45.4-47.8%) for P (P value = 0.24).
Under the limitations of this study, it may be concluded that the mechanical properties of the two 3D printed resins tested are equal, and thus, no differences in their clinical performance are expected.
三维（3D）打印技术是许多正畸矫治器的新兴制造工艺，本研究旨在评估树脂基材料的机械性能，作为正畸托槽内部制备的替代材料。
本研究纳入了两种用于临时（T）和永久（P）冠制作的 3D 打印树脂。每种树脂制造 10 个块体，通过 3D 打印机嵌入丙烯酸树脂后，对样本进行金相研磨和抛光，然后进行仪器压痕测试（IIT）。使用维氏压头记录每个样本的力-压痕深度曲线，确定马氏体硬度（HM）、压痕模量（E）和弹性指数（η）。计算描述性统计量后，使用 Wilcoxon 秩和检验在 5%的水平上考虑样本内测量的聚类，检验两种材料类型之间的差异。
两种测试材料的机械性能无统计学差异：HM：T 组中位数 279 N/mm（四分位距 [IQR] 275-287 N/mm），P 组中位数 279 N/mm（IQR 270-285 N/mm）（P 值=0.63）；E：T 组中位数 5548 MPa（IQR 5425-5834 MPa），P 组中位数 5644 MPa（IQR 5420-5850 MPa）（P 值=0.84）；η：T 组中位数 47.1%（46.0-47.7%），P 组中位数 46.0%（IQR 45.4-47.8%）（P 值=0.24）。
在本研究的限制条件下，可以得出结论，两种测试的 3D 打印树脂的机械性能相等，因此预计其临床性能没有差异。
