State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; Department of Oral Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; University Hospital Tübingen, Section Medical Materials Science and Technology, Osianderstrasse 2-8, Tübingen 72076, Germany.
Department of Orthodontics, University Hospital Tübingen, Osianderstrasse 2-8, Tübingen 72076, Germany.
Dent Mater. 2021 May;37(5):e314-e327. doi: 10.1016/j.dental.2021.01.016. Epub 2021 Feb 18.
Since the post-rinsing time is inconsistently recommended, this study aims to investigate the effect of post-rinsing time on the flexural strength and cytotoxicity of an stereolithographically (SLA) printed orthodontic splint material.
SLA-printed specimens were ultrasonically rinsed with isopropanol (IPA) for 5 min, 12 min, 20 min, 30 min, 1 h, and 12 h, respectively. Surface characterization was conducted by scanning electron microscopy and roughness measurements. Flexural strength was evaluated using a three-point bending test. Cytotoxicity was determined by direct contact test and extract test. For both tests, cell viability (live/dead staining) and cell metabolic activity (CCK-8 assay) were evaluated. Additionally, water sorption and water solubility were tested to analyze the mass loss from immersion.
No apparent surface alterations could be detected on the samples post-rinsed for less than 1 h. In contrast, when the post-rinsing time was prolonged to 12 h, surface fissures could be observed. Flexural strength linearly decreased with increasing post-rinsing time. All post-processed specimens did not show an obvious cytotoxic effect.
The removal of cytotoxic methacrylate monomers by post-rinsing with IPA could be achieved in 5 min. Extending post-rinsing time could not improve the cytocompatibility of the SLA-printed orthodontic splint material, and may result in a decrease in flexural strength.
由于后冲洗时间的推荐不一致，本研究旨在探讨后冲洗时间对立体光固化（SLA）打印正畸夹板材料的弯曲强度和细胞毒性的影响。
SLA 打印的样本分别用异丙醇（IPA）超声冲洗 5 分钟、12 分钟、20 分钟、30 分钟、1 小时和 12 小时。通过扫描电子显微镜和粗糙度测量进行表面特性分析。采用三点弯曲试验评估弯曲强度。通过直接接触试验和提取试验测定细胞毒性。对于这两种测试，都评估了细胞活力（死活染色）和细胞代谢活性（CCK-8 测定）。此外，还测试了吸水率和溶解度，以分析浸泡过程中的质量损失。
冲洗时间少于 1 小时的样本表面没有明显的变化。相比之下，当后冲洗时间延长至 12 小时时，可观察到表面裂缝。弯曲强度随后冲洗时间的增加呈线性下降。所有后处理的样本均未显示明显的细胞毒性作用。
用 IPA 后冲洗 5 分钟即可去除具有细胞毒性的甲基丙烯酸盐单体。延长后冲洗时间不能提高 SLA 打印正畸夹板材料的细胞相容性，反而可能导致弯曲强度降低。
