Department of Operative Dentistry, School of Dentistry, Tehran University of Medical Sciences, Iran.
Department of Periodontology, Dental School, Mashhad University of Medical Sciences, Iran.
Dent Med Probl. 2020 Jul-Sep;57(3):247-253. doi: 10.17219/dmp/118123.
The surface microhardness of dental composites greatly affects the durability of restorations.
The aim of this study was to compare the surface microhardness of a self-adhesive composite with that of other conventional composites. The effect aging has on surface microhardness was also evaluated.
In this in vitro experimental study, the composite resins were poured into molds measuring 3 mm × 3 mm × 6 mm and cured for 40 s. The samples were then immersed in distilled water at 37°C for 24 h. After polishing, the surface microhardness of the samples was measured using the Vickers hardness tester. For this purpose, a 100-gram load was applied to 3 points on the surface of each composite sample for 20 s, and the mean value of surface microhardness was used as the Vickers hardness number. The samples were then subjected to 30,000 thermal cycles at 5-55°C in order to age them; after that, their surface microhardness was measured again. The one-way analysis of variance (ANOVA) was used for the statistical analysis.
The maximum hardness value before and after aging belonged to Filtek® Z250, followed by Premise™ Flow and Vertise™ Flow, with significant differences between them (p < 0.001). After aging, the surface microhardness of all composites decreased significantly (p < 0.001). The effect of aging on surface microhardness was the same in all groups (p > 0.05).
The surface microhardness of composites was significantly different before and after aging. All composites experienced a reduction in their surface microhardness after aging.
牙科复合材料的表面显微硬度极大地影响修复体的耐用性。
本研究旨在比较自粘接型复合材料与其他常规复合材料的表面显微硬度，并评估老化对表面显微硬度的影响。
在这项体外实验研究中，将复合材料树脂浇铸到 3mm×3mm×6mm 的模具中，并进行 40s 的光固化。然后将样本浸入 37°C 的蒸馏水中 24h。抛光后，使用维氏硬度测试仪测量样本的表面显微硬度。为此，在每个复合材料样本表面的 3 个点上施加 100 克的负荷 20s，将表面显微硬度的平均值作为维氏硬度值。然后，将样本在 5-55°C 下进行 30000 次热循环老化；之后，再次测量其表面显微硬度。采用单因素方差分析（ANOVA）进行统计学分析。
老化前后最大硬度值属于 Filtek® Z250，其次是 Premise™ Flow 和 Vertise™ Flow，它们之间存在显著差异（p<0.001）。老化后，所有复合材料的表面显微硬度均显著降低（p<0.001）。老化对所有组的表面显微硬度的影响相同（p>0.05）。
复合材料的表面显微硬度在老化前后有显著差异。所有复合材料在老化后表面显微硬度均降低。
