Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
Private Practice, Limassol, Cyprus.
Eur J Orthod. 2022 Jan 25;44(1):51-55. doi: 10.1093/ejo/cjab022.
To investigate alterations in the mechanical properties of in-house three-dimensional (3D) printed orthodontic aligners after intraoral ageing.
Sixteen 3D-printed aligners (TC-85DAC resin, Graphy, Seoul, Korea) were used for the purpose of the study, which were divided into 10 control (not used) aligners and 6 materials retrieved from 4 patients after 1-week service (retrieved group). Samples from the control group were analysed by attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) spectroscopy. Samples from control/retrieved groups were embedded resin and subjected to instrumented indentation testing (IIT) to record force-indentation depth curves, calculating the following (as per ISO 14577-1, 2002 standard): Martens hardness (HM), indentation modulus (EIT), and elastic index (ηIT), and the indentation relaxation index (RIT). Differences between control and retrieved 3D-printed aligners were checked with Mann-Whitney/t-tests at an alpha = 5%.
ATR-FTIR analysis showed that aligners were made of a vinyl ester-urethane material. The results of the IIT testing were: HM (control: median 91.5 N/mm2, interquartile range [IQR] 88.0-93.0/as-retrieved: median 90.5 N/mm2, IQR 89.0-93.0); EIT (control, mean 2616.3 MPa, standard deviation [SD] 107.0 MPa/retrieved, mean 2673.2 MPa, SD 149.4 MPa); ηIT (control: median 28.6%, IQR 28.2-30.9%/as-retrieved: median 29.0%, IQR 28.7-29.2%); and RIT (control: median 45.5%, IQR 43.0-47.0%/as-retrieved: median 45.1%, IQR 45.0-45.3%). No differences between as-retrieved and control aligners were found for any of the mechanical properties tested (P > 0.05 in all instances).
The mechanical properties of the in-house 3D-printed aligners tested were not affected after 1 week in service period.
研究口腔内老化对自制 3D 打印正畸保持器力学性能的影响。
本研究使用了 16 个 3D 打印保持器（TC-85DAC 树脂，Graphy，首尔，韩国），分为 10 个对照组（未使用）和 6 个从 4 名患者服务 1 周后回收的材料组。对照组的样本通过衰减全反射傅里叶变换红外（ATR-FTIR）光谱分析。对照组/回收组的样本用树脂包埋，进行仪器压痕测试（IIT），记录力-压痕深度曲线，计算以下参数（符合 ISO 14577-1，2002 标准）：马氏体硬度（HM）、压痕模量（EIT）和弹性指数（ηIT）以及压痕松弛指数（RIT）。对照组和回收 3D 打印保持器之间的差异用曼-惠特尼/t 检验（α=5%）进行检查。
ATR-FTIR 分析表明，保持器由乙烯酯-氨酯材料制成。IIT 测试结果为：HM（对照组：中位数 91.5 N/mm2，四分位距 [IQR] 88.0-93.0/回收组：中位数 90.5 N/mm2，IQR 89.0-93.0）；EIT（对照组，平均值 2616.3 MPa，标准差 [SD] 107.0 MPa/回收组，平均值 2673.2 MPa，SD 149.4 MPa）；ηIT（对照组：中位数 28.6%，IQR 28.2-30.9%/回收组：中位数 29.0%，IQR 28.7-29.2%）；RIT（对照组：中位数 45.5%，IQR 43.0-47.0%/回收组：中位数 45.1%，IQR 45.0-45.3%）。在所有测试的力学性能中，回收组和对照组之间没有差异（所有情况下 P > 0.05）。
在 1 周的使用期内，测试的自制 3D 打印保持器的力学性能没有受到影响。
