Hamedi Rad Fahimeh, Ghaffari Tahereh, Tamgaji Raana
Dept. of Prosthodontics, School of Dentistry, Tabriz, University of Medical Sciences, Tabriz, Iran.
Postgraduate Student of Oral Medicine, School of Dentistry, Tabriz, University of Medical Sciences, Tabriz, Iran.
J Dent (Shiraz). 2017 Jun;18(2):136-142.
Evaluation of the color stability of materials used for the fabrication of the base of complete and partial removable dentures provides important information in relation to their clinical service. The color stability of nylon-based polymers as denture bases, compared to that of acrylic resins, has not been extensively evaluated since to date.
The aim of the present study was to evaluate the color stability of conventional polymethyl methacrylate and nylon-based polymer materials used for the fabrication of the base of complete and partial removable dentures.
Twenty samples were evaluated in the present study. One nylon-based polymer and one heat-cured acrylic resin were seleted for the purpose of the study. Ten disk samples, measuring 10 mm in diameter and 2 mm in thickness, were prepared from each material according to the manufacturers' instructions. The samples were evaluted with the CIELAB sysem using spectrophtometery at baseline and after irradiation with UV light for 100 and 200 hours and thermocycling. One-way ANOVA and post hoc paired t-test were used to compare the color stability of the two groups. Statistical significance was set at < 0.05.
After 100 hours of irradiation with UV light and thermocycling, color changes were tangible in both materials. After 200 hours of irradiation with UV light and thermocycling, both materials exhibited a decrease in glaze. In general, chromatic changes in the acrylic resin were more noticeable.
Accelerated aging affected the color stability of the acrylic resin and nylon-based polymer, < 0.05 for Δa200 and Δb200 and ΔL100; however, at the end of the study both materials exhibited clinically acceptable color stability (ΔE<3.7).
评估用于制作全口和局部可摘义齿基托的材料的颜色稳定性，可为其临床应用提供重要信息。迄今为止，与丙烯酸树脂相比，尼龙基聚合物作为义齿基托的颜色稳定性尚未得到广泛评估。
本研究的目的是评估用于制作全口和局部可摘义齿基托的传统聚甲基丙烯酸甲酯和尼龙基聚合物材料的颜色稳定性。
本研究评估了20个样本。为该研究选择了一种尼龙基聚合物和一种热固化丙烯酸树脂。根据制造商的说明，从每种材料制备10个直径为10毫米、厚度为2毫米的圆盘样本。使用CIELAB系统，在基线以及紫外线照射100小时和200小时并进行热循环后，用分光光度计对样本进行评估。采用单因素方差分析和事后配对t检验比较两组的颜色稳定性。设定统计学显著性为<0.05。
紫外线照射100小时并进行热循环后，两种材料均出现明显的颜色变化。紫外线照射200小时并进行热循环后，两种材料的光泽度均有所下降。总体而言，丙烯酸树脂的颜色变化更为明显。
加速老化影响了丙烯酸树脂和尼龙基聚合物的颜色稳定性，Δa200、Δb200和ΔL100的P<0.05；然而，在研究结束时，两种材料均表现出临床上可接受的颜色稳定性（ΔE<3.7）。
