Department of Prosthodontics, University of Marmara, Faculty of Dentistry, Istanbul, Turkey.
J Prosthodont. 2010 Jan;19(1):47-51. doi: 10.1111/j.1532-849X.2009.00495.x. Epub 2009 Dec 3.
Acetal resin has been used as an alternative denture base and clasp material since 1986. The manufacturers claim that acetal resin has superior physical properties when compared to conventional denture base acrylic resins. Limited information is available about transverse strengths of acetal resin. The purpose of this investigation was to compare transverse strengths of pink and white acetal resins to transverse strengths of conventional heat-polymerized polymethylmethacrylate (PMMA) resin in increasing durations of water storage.
A transverse strength test was performed in accordance with International Standards Organization (ISO) specification No 1567. Twenty 65 x 10 x 2.5 mm(3) specimens of each resin were prepared; five specimens of each resin group were subjected to three-point bending test after 50 hours, 30 days, 60 days, and 180 days of water storage in distilled water at 37 degrees C. Experimental groups' transverse strengths were compared by three-way ANOVA and Duncan's multiple range tests.
Transverse strength of PMMA denture base material was found to be in accordance with the requirements of ISO specification No 1567. Transverse strengths of white and pink acetal resin could not be calculated in this study, as white and pink acetal resin specimens did not break at the maximum applied force in the three-point bending test. Flexural strength of acetal resin was found to be within the ISO specification limits. As the water storage time increased, the deflection values of PMMA showed no significant difference (p > 0.05). Both the white and pink acetal resin showed significant increase in deflection as the water storage time was increased from 50 hours to 180 days (p < 0.05).
The results of this study indicated that transverse strength values of PMMA were within the ISO specification limit. Water storage time (50 hours, 30, 60, and 180 days) had no statistically significant effect on the transverse strength and deflection of PMMA. Acetal resin suffered from permanent deformation, but did not break in the three-point bending test. Acetal resin showed significant increase in deflection as the water storage time was increased from 50 hours to 180 days. All materials tested demonstrated deflection values in compliance with ISO specification No 1567.
自 1986 年以来，乙缩醛树脂已被用作替代义齿基托和卡环材料。制造商声称，与传统义齿基托丙烯酸树脂相比，乙缩醛树脂具有更优越的物理性能。关于乙缩醛树脂的横向强度的信息有限。本研究的目的是比较粉色和白色乙缩醛树脂与传统热聚合聚甲基丙烯酸甲酯（PMMA）树脂在不同水储存时间下的横向强度。
根据国际标准化组织（ISO）规范 No 1567 进行了横向强度测试。制备了每种树脂的 20 个 65 x 10 x 2.5mm(3)试件；每组 5 个试件在 37°C蒸馏水中储存 50 小时、30 天、60 天和 180 天后进行三点弯曲试验。通过三因素方差分析和 Duncan 多重范围检验比较实验组的横向强度。
发现 PMMA 义齿基托材料的横向强度符合 ISO 规范 No 1567 的要求。在本研究中，无法计算白色和粉色乙缩醛树脂的横向强度，因为在三点弯曲试验中，白色和粉色乙缩醛树脂试件在最大施加力下没有断裂。乙缩醛树脂的抗弯强度在 ISO 规范范围内。随着水储存时间的增加，PMMA 的挠度值没有显著差异（p > 0.05）。随着水储存时间从 50 小时增加到 180 天，白色和粉色乙缩醛树脂的挠度均显著增加（p < 0.05）。
本研究结果表明，PMMA 的横向强度值在 ISO 规范范围内。水储存时间（50 小时、30 天、60 天和 180 天）对 PMMA 的横向强度和挠度没有统计学上的显著影响。乙缩醛树脂发生永久变形，但在三点弯曲试验中未断裂。随着水储存时间从 50 小时增加到 180 天，乙缩醛树脂的挠度显著增加。所有测试材料的挠度值均符合 ISO 规范 No 1567。
