Department of Prosthetic Dentistry, University of Mosul, Mosul, Iraq.
Clin Exp Dent Res. 2024 Feb;10(1):e828. doi: 10.1002/cre2.828.
The second rule of the 4Rs concept (Reduce, Reuse, Recycle, and Recover) was applied in this study using recycled acrylic resin to improve the hardness and study the effect of aging on the hardness of heat cured denture base resins.
Forty heat-cured acrylic resin samples were prepared and divided into control and modified groups. The hardness was tested using a type D durometer hardness tester for evaluating the effect of the thermal aging process on the hardness in the control and modified groups. The samples were either subjected to thermal aging (the specimens thermo-cycled 10 cycles per day between 55°C and 5°C with a 30-s dwell time) or were not.
The mean difference in hardness between specimens with and without aging in the modified group increased with increasing concentrations of incorporated recycled acrylic resin. Independent samples t test revealed that the hardness values of modified groups with aging were significantly higher than in those without aging (p ≤ 0.05). ANOVA revealed that the modified group revealed a significant increase in hardness than that of the control group (p ≤ 0.05).
Recycling and reuse of acrylic resins improved the hardness of denture base resins. The aging period significantly affected the hardness values of the control and modified groups.
本研究应用 4R 原则（减少、再利用、再循环和回收）中的第二条规则，使用回收的丙烯酸树脂来提高硬度，并研究热固化义齿基托树脂老化对硬度的影响。
制备 40 个热固化丙烯酸树脂样本，并分为对照组和改良组。使用 D 型硬度计测试硬度，以评估热老化过程对对照组和改良组硬度的影响。部分样本进行热老化（每天在 55°C 和 5°C 之间进行 10 个热循环，每个循环 30 秒），部分不进行热老化。
改良组中，有老化和无老化的样本之间的硬度平均值差异随回收丙烯酸树脂掺入浓度的增加而增加。独立样本 t 检验显示，有老化的改良组的硬度值明显高于无老化的改良组（p≤0.05）。方差分析显示，改良组的硬度明显高于对照组（p≤0.05）。
回收和再利用丙烯酸树脂提高了义齿基托树脂的硬度。老化期显著影响对照组和改良组的硬度值。
