Graduate student, Gerodontology and Oral Rehabilitation, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Yushima, Bunkyo, Tokyo, Japan.
Assistant Professor, Gerodontology and Oral Rehabilitation, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Yushima, Bunkyo, Tokyo, Japan.
J Prosthet Dent. 2021 Apr;125(4):695-702. doi: 10.1016/j.prosdent.2020.02.023. Epub 2020 May 13.
The appropriate postpolymerization of stereolithography (SLA) resins with the least effect on dimensional accuracy and with optimal polymerization is unclear.
The purpose of this in vitro study was to investigate the dimensional accuracy and degree of polymerization of a photopolymer resin for SLA with different postpolymerizing times and temperatures.
Sixty 1.5-mm-thick specimens were made from clear photopolymer resin with a 3D printer to simulate a maxillary complete denture. They were postpolymerized for different periods (15 and 30 minutes) at 3 different temperatures (40 °C, 60 °C, and 80 °C). Both prepolymerization and postpolymerization gap sizes for each specimen were measured at 5 different locations under a stereomicroscope. The tissue surface was scanned before and after polymerization, and the images were superimposed. The deviation was analyzed by using computer-aided design (CAD) software; root mean square estimates (RMSE) and color map data were obtained. Fourier transform infrared spectrometry was used to determine the degree of conversion (DC) of all specimens. The Kruskal-Wallis and Mann-Whitney tests were used to calculate the difference value of the gap sizes (α=.05). One-way ANOVA and the Tukey test were used for RMSE and DC (α=.05).
The smallest average change in gap sizes was found at 15 minutes and 40 °C, and the largest change at 30 minutes and 80 °C. The lowest RMSE was obtained at 30 minutes and 40 °C (P<.05). On the color map, a uniform deposited layer was created at 15 minutes and 40 °C and 30 minutes and 40 °C. The highest DC was found at 30 minutes and 60 °C, which differed significantly from 15 minutes and 40 °C (P<.05). The lowest degree of polymerization was found at 30 minutes and 40 °C.
The polymerizing temperature exerted a greater effect than polymerizing time, with lower temperatures leading to improved fit and tissue surface accuracy. The recommended parameters for SLA polymerization are 15 minutes and 40 °C. These conditions offered high dimensional accuracy, favorable surface tissue adaptation, and satisfactory DC.
立体光固化（SLA）树脂的后聚合，以达到最小的尺寸精度影响和最佳聚合效果，目前仍不明确。
本体外研究的目的是调查不同后聚合时间和温度下，用于 SLA 的光聚合树脂的尺寸精度和聚合度。
使用 3D 打印机制作 60 个 1.5 毫米厚的样本，模拟上颌全口义齿。将它们在 3 种不同温度（40°C、60°C 和 80°C）下进行不同时间（15 分钟和 30 分钟）的后聚合。在体视显微镜下，在 5 个不同位置测量每个样本的预聚合和后聚合间隙尺寸。聚合前后对组织表面进行扫描，并对图像进行叠加。使用计算机辅助设计（CAD）软件分析偏差；获得均方根估计值（RMSE）和颜色图数据。使用傅里叶变换红外光谱法测定所有样本的转化率（DC）。使用 Kruskal-Wallis 和 Mann-Whitney 检验计算间隙尺寸的差值（α=.05）。使用单向方差分析和 Tukey 检验进行 RMSE 和 DC 的分析（α=.05）。
在 15 分钟和 40°C 时，发现平均间隙尺寸变化最小，在 30 分钟和 80°C 时变化最大。在 30 分钟和 40°C 时，RMSE 最低（P<.05）。在颜色图上，在 15 分钟和 40°C 以及 30 分钟和 40°C 时，形成了均匀的沉积层。在 30 分钟和 60°C 时，发现 DC 最高，与 15 分钟和 40°C 有显著差异（P<.05）。在 30 分钟和 40°C 时，聚合度最低。
聚合温度的影响大于聚合时间，较低的温度可提高拟合度和组织表面精度。SLA 聚合的推荐参数为 15 分钟和 40°C。这些条件提供了高精度的尺寸、良好的表面组织适应性和令人满意的 DC。
