Musavinasab Seyed Mostafa, Norouzi Zahra
Department of Restorative and Cosmetic Dentistry, Dental School Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran.
Department of Operative Dentistry, School of Dentistry, Shahrekord University of Medical Sciences, Shahrekord, Iran.
Front Dent. 2023 Jun 13;20:20. doi: 10.18502/fid.v20i20.12912. eCollection 2023.
Hardness is relevant to the degree of conversion (DC) and depth of cure (DoC). The aim of this study was to determine the micro-hardness and DoC of conventional and bulk-fill composite resins in class II restorations using metal and clear matrix bands. Twelve specimens of each of the two composite resins, , Filtek Z350 XT bulk-fill and Gradia posterior conventional composite, were prepared in the form of a class II cavity in a tooth mold, using a clear or metal matrix band. All specimens were cured and stored at 37°C for 24 hours. Vickers hardness was measured as a function of DoC at 2mm intervals. Data were analyzed by two-way ANOVA (alpha=0.05). The bulk-fill composite exhibited significantly higher hardness levels than the conventional composite in all tested surfaces (P<0.001). However, while the metal matrix band had a significant impact on the bottom surface (P=0.059) and also on the furthest surface from the matrix and light source (P=0.04), it did not have a consistent effect across all tested surfaces. The simultaneous interaction of the composites and matrix band types in all surfaces, did not show significant differences in hardness values. The highest bottom-to-top surface hardness ratio (73%) was observed in the conventional composite near the metal matrix band. In deep class II cavities, the bottom-to-top surface hardness ratio did not reach the maximum of 80%, neither for bulk-fill nor conventional posterior composites. Therefore, in such cavities extended light-curing and more incremental composite placement is needed.
硬度与固化程度（DC）和固化深度（DoC）相关。本研究的目的是使用金属和透明基质带确定II类修复体中传统复合树脂和大块充填复合树脂的显微硬度和固化深度。使用透明或金属基质带，在牙齿模型中制备两种复合树脂（Filtek Z350 XT大块充填树脂和Gradia后牙传统复合树脂）各自的12个样本，呈II类洞形。所有样本均进行固化，并在37°C下储存24小时。以2mm的间隔测量维氏硬度作为固化深度的函数。数据通过双向方差分析进行分析（α = 0.05）。在所有测试表面上，大块充填复合树脂的硬度水平均显著高于传统复合树脂（P < 0.001）。然而，虽然金属基质带对底面有显著影响（P = 0.059），对距基质和光源最远的表面也有显著影响（P = 0.04），但在所有测试表面上其影响并不一致。复合材料和基质带类型在所有表面上的同时相互作用，在硬度值上未显示出显著差异。在靠近金属基质带的传统复合树脂中观察到最高的从底面到顶面的硬度比（73%）。在深II类洞中，无论是大块充填复合树脂还是传统后牙复合树脂，从底面到顶面的硬度比均未达到80%的最大值。因此，在这种洞形中，需要延长光固化时间并采用更多分层放置复合树脂的方法。
