Rizzante Fabio A P, Azzer Michael, Moghaddam Nima G, Watson Thomas, Moura Guilherme F, Furuse Adilson Y
Associate Professor and Assistant Dean for Innovation, James B. Edwards College of Dental Medicine, Medical University of South Carolina (MUSC), Charleston, SC.
Graduate student, James B. Edwards College of Dental Medicine, Medical University of South Carolina (MUSC), Charleston, SC.
J Prosthet Dent. 2025 Apr;133(4):1091.e1-1091.e6. doi: 10.1016/j.prosdent.2025.01.006. Epub 2025 Feb 13.
Fast prototyped, or 3-dimensionally (3D) printed, materials enhance clinical efficiency when compared with other manufacturing methods. Nevertheless, standardization and information regarding the influence of different postprocessing protocols on the final physical and mechanical properties of 3D printed parts is lacking.
The purpose of this in vitro study was to evaluate the effect of different polymerization methods and times on the flexural strength, microhardness, and color stability of a 3D printed resin (OnX; SprintRay).
A total of 40 disks (Ø10×2 mm) and 40 bars (10×2×2 mm) were 3D printed, washed, and subdivided into 4 groups (n=10) according to the polymerization protocol: VALO Grand light polymerization unit for 40 and 120 seconds (VG40s andVG120s) and ProCure 2 polymerization chamber for 1 and 2 cycles (PC×1 and PC×2). The bars were stored in distilled water at 37 °C for 24 hours, and a 3-point bend test was performed with a universal testing machine with an 8-mm span and a downward movement at a rate of 0.5 mm/minute until fracture. The disks were polished with abrasive disks. Color stability was assessed after polymerization (baseline), after 1 and 7 days in dark, dry storage at 37 °C, and after 3 days of artificial aging in deionized water at 60 °C. Values of b* were used to calculate yellow shift/Δb* values after 3 days of artificial aging. Microhardness after 7 days in dark, dry storage was assessed with a Knoop indenter. The data were assessed for homogeneity using the Levene test and for normality using the Shapiro-Wilk test. Two-way ANOVA (flexural strength, microhardness, and Δb* tests) and 3-way repeated-measures ANOVA (color stability test) were followed by the Tukey HSD post hoc test (α=.05 for all tests).
For microhardness, the polymerization unit (P<.001), polymerization cycles (P=.003), and interaction between both factors (P=.005) were significantly different, with VG40s=VG120s>PC×1>PC×2. For flexural strength, the polymerization unit (P<.001), polymerization cycles (P<.001), and interaction between both factors (P<.001) were significantly different, with VG120s=PC×1=PC×2>VG40s. For color stability, the polymerization unit (P=.009), time (P<.001), and interaction between time and polymerization unit (P<.001) and time, polymerization unit, and cycle (P=.01) were significantly different. After 3 days of artificial aging, PC×1=PC×2>VG40s=VG120s. Significantly different Δb* was found for polymerization unit (P<.001) and polymerization cycles (P=.002), with VG120s<VG40s=PC×2≤PC×1.
Resins polymerized using VG120s produced similar or better microhardness, flexural strength, and color stability results than PC while significantly decreasing the postpolymerization time. Specimens polymerized with PC×2 showed the lowest microhardness. Excessively increased polymerization time may jeopardize the properties of 3D printed parts.
与其他制造方法相比，快速成型或三维（3D）打印材料可提高临床效率。然而，目前缺乏关于不同后处理方案对3D打印部件最终物理和机械性能影响的标准化及相关信息。
本体外研究的目的是评估不同聚合方法和时间对3D打印树脂（OnX；SprintRay）的弯曲强度、显微硬度和颜色稳定性的影响。
共3D打印40个圆盘（直径10×2mm）和40个棒材（10×2×2mm），清洗后根据聚合方案分为4组（每组n = 10）：使用VALO Grand光聚合装置分别聚合40秒和120秒（VG40s和VG120s），以及使用ProCure 2聚合腔分别聚合1个循环和2个循环（PC×1和PC×2）。将棒材在37°C蒸馏水中储存24小时，然后使用跨度为8mm、向下移动速度为0.5mm/分钟的万能试验机进行三点弯曲试验，直至断裂。用砂纸对圆盘进行抛光。在聚合后（基线）、在37°C黑暗干燥环境中储存1天和7天后以及在60°C去离子水中人工老化3天后评估颜色稳定性。使用b值计算人工老化3天后的黄变/Δb值。在黑暗干燥环境中储存7天后，用努氏压头评估显微硬度。使用Levene检验评估数据的同质性，使用Shapiro-Wilk检验评估数据的正态性。采用双向方差分析（弯曲强度、显微硬度和Δb*测试）和三向重复测量方差分析（颜色稳定性测试），随后进行Tukey HSD事后检验（所有测试的α = 0.05）。
对于显微硬度，聚合装置（P <.001）、聚合循环次数（P =.003）以及两个因素之间的相互作用（P =.005）存在显著差异，其中VG40s = VG120s > PC×1 > PC×2。对于弯曲强度，聚合装置（P <.001）、聚合循环次数（P <.001）以及两个因素之间的相互作用（P <.001）存在显著差异，其中VG120s = PC×1 = PC×2 > VG40s。对于颜色稳定性，聚合装置（P =.009）、时间（P <.001）以及时间与聚合装置之间的相互作用（P <.001）以及时间、聚合装置和循环次数之间的相互作用（P =.01）存在显著差异。人工老化3天后，PC×1 = PC×2 > VG40s = VG120s。发现聚合装置（P <.001）和聚合循环次数（P =.002）的Δb*存在显著差异，其中VG120s < VG40s = PC×2 ≤ PC×1。
使用VG120s聚合的树脂在显微硬度、弯曲强度和颜色稳定性方面产生的结果与PC相似或更好，同时显著缩短了聚合后时间。用PC×2聚合的试样显微硬度最低。过度增加聚合时间可能会损害3D打印部件的性能。
