Azpiazu-Flores Francisco X, Elfana Ahmed, Yang Chao-Chieh, Morton Dean, Lin Wei-Shao
Department of Restorative & Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, Ohio, USA.
Department of Prosthodontics, Indiana University School of Dentistry, Indianapolis, Indiana, USA.
J Prosthodont. 2024 Oct 8. doi: 10.1111/jopr.13963.
This study evaluated the effect of thermocycling and three different surface finishing protocols on the flexural strength and surface hardness of a novel photopolymer intended for manufacturing monolithic polychromatic dental prostheses using PolyJet 3D printing.
A total of 90 specimens were manufactured using a photopolymer for 3D printing monolithic polychromatic dental prostheses using PolyJet technology (TrueDent; Stratasys USA). The specimens were divided into three groups (n = 30) according to the surface finishing protocol used: The control group Pumice+Moldent (Pumice), Pumice+Optiglaze (Optiglaze), and Polycril+Moldent (Polycril). Half of the specimens of each group (n = 15) were subjected to 5000 thermocycles (Thermocycling Unit OMC350TSX; Odeme Dental Research, Santa Catarina, Brazil), The other half was stored in distilled water at room temperature for 7 days before testing. The flexural strength of the specimens was assessed in a universal testing machine (MTS Sintech ReNew; MTS Systems Corp, Aiden Prairie, MN), and the Vicker's surface hardness was evaluated with a microhardness tester (Micro indentation Hardness Tester LM247AT; Leco Instruments Ltd, Ontario, Canada). The resulting data was analyzed using two-way ANOVA tests, and Fisher's protected least significant differences (α = 0.05) in a professional statistical analysis computer program (SAS v9.4, SAS Institute, Cary, NC) RESULTS: The two-way ANOVA tests suggested a statistically significant effect of thermocycling and the surface finishing protocol on the flexural strength (p = 0.01) but without significant interaction between both independent variables (p = 0.18). The post hoc analysis revealed no significant differences in the flexural strength between groups without thermocycling (p > 0.05). Thermocycling decreased the flexural strength of all groups (p < 0.05), and the Optiglaze group exhibited significantly higher flexural strength than the Polycril and Pumice groups after thermocycling (p < 0.01). Regarding the surface hardness, the two-way ANOVA indicated a significant 2-way interaction between thermocycling and the surface of the finishing protocol (p = 0.01). The post hoc analysis showed that the Optiglaze group had significantly higher hardness than the other groups, both before and after thermocycling (p < 0.01) After thermocycling, a significant decrease in surface hardness was observed in the Polycril and Pumice groups (p < 0.01).
Surface finishing protocols and artificial aging can affect the surface hardness and flexural strength of the dental prostheses manufactured using the photopolymer studied. Careful polishing and surface finishing are required to ensure favorable clinical performance. Coating with a photopolymerizable glaze material seems to be a favorable surface treatment for monolithic polychromatic complete dentures fabricated using PolyJet 3D printing.
本研究评估了热循环和三种不同的表面处理方案对一种新型光聚合物的弯曲强度和表面硬度的影响，该光聚合物用于使用PolyJet 3D打印制造整体式多色牙科假体。
使用一种用于通过PolyJet技术（TrueDent；美国Stratasys公司）3D打印整体式多色牙科假体的光聚合物制造了总共90个试样。根据所使用的表面处理方案，将试样分为三组（n = 30）：对照组为浮石+ Moldent（浮石）、浮石+ Optiglaze（Optiglaze）和Polycril + Moldent（Polycril）。每组的一半试样（n = 15）进行5000次热循环（热循环单元OMC350TSX；巴西圣卡塔琳娜州的Odeme牙科研究公司），另一半在测试前在室温下的蒸馏水中储存7天。在万能试验机（MTS Sintech ReNew；美国明尼苏达州艾登草原市的MTS系统公司）中评估试样 的弯曲强度，并用显微硬度计（显微压痕硬度计LM247AT；加拿大安大略省的Leco仪器有限公司）评估维氏表面硬度。使用双向方差分析测试对所得数据进行分析，并在专业统计分析计算机程序（SAS v9.4，美国北卡罗来纳州卡里市的SAS研究所）中进行Fisher保护最小显著差异（α = 0.05）分析。结果：双向方差分析测试表明，热循环和表面处理方案对弯曲强度有统计学上的显著影响（p = 0.01），但两个自变量之间没有显著相互作用（p = 0.18）。事后分析显示，未进行热循环的组之间的弯曲强度没有显著差异（p>0.05）。热循环降低了所有组的弯曲强度（p<0.05），并且在热循环后，Optiglaze组的弯曲强度显著高于Polycril组和浮石组（p<0.01）。关于表面硬度，双向方差分析表明热循环和表面处理方案之间存在显著的双向相互作用（p = 0.01）。事后分析表明，Optiglaze组在热循环前后的硬度均显著高于其他组（p<0.01）。热循环后，Polycril组和浮石组的表面硬度显著降低（p<0.01）。
表面处理方案和人工老化会影响使用所研究的光聚合物制造的牙科假体的表面硬度和弯曲强度。需要仔细抛光和表面处理以确保良好的临床性能。用可光聚合的釉质材料涂层似乎是对使用PolyJet 3D打印制造的整体式多色全口义齿进行表面处理的有利方法。
