Effects of erosive challenge on the morphology and surface properties of luting cements

Abstract Introduction Few studies investigated the surface properties of luting cements after erosive challenge. Objective To evaluate the surface roughness (Ra), Vickers hardness (VHN) and morphology of 4 luting cements after erosive challenge. Material and method Twenty specimens of each cement were prepared (4×2mm) and divided into experimental (erosive challenge) and control (artificial saliva) groups (n=10): Rely X U200 (U200); Rely X ARC (ARC); Ketac Cem Easy Mix (Ketac) and Zinc phosphate (ZnP). The erosive challenge was performed by four daily erosive cycles (90s) in a cola drink and 2 h in artificial saliva over 7 days. Ra and VHN readings were performed before and after erosion. The percentage of hardness loss (%VHN) was obtained after erosion. The surface morphology was analyzed by scanning electron microscopy (SEM). ANOVA, Tukey and Student-T tests were used (α=0.05). Result After erosion, all luting cements had increase in Ra values and U200 and ZnP groups had the highest %VHN. After saliva immersion, only U200 and ZnP groups had significant increases in Ra values and there were no significant differences among the groups in %VHN. SEM analysis showed that Ketac and ZnP groups had rough and porous surfaces, and U200 group had higher resin matrix degradation than ARC group. Conclusion Erosive challenge with a cola drink affected the surface properties of all luting cements.

摘要
引言 目前鲜有研究探讨侵蚀性暴露后粘接水门汀（luting cements）的表面特性。
目的 评估4种粘接水门汀经侵蚀性暴露后的表面粗糙度（surface roughness, Ra）、维氏硬度（Vickers hardness number, VHN）及表面形貌。
材料与方法 制备每种粘接水门汀的试件20个（尺寸为4×2mm），分为实验组（接受侵蚀性暴露）与对照组（置于人工唾液中），每组10个样本：Rely X U200（U200）、Rely X ARC（ARC）、Ketac Cem Easy Mix（Ketac）以及磷酸锌水门汀（Zinc phosphate, ZnP）。侵蚀性暴露方案为：每日将试件置于可乐饮料中进行90秒的侵蚀循环，随后置于人工唾液中孵育2小时，持续7天。分别在侵蚀前后检测试件的Ra与VHN值，并计算侵蚀后的硬度损失百分比（%VHN）。采用扫描电子显微镜（scanning electron microscopy, SEM）分析试件的表面形貌。采用方差分析（ANOVA）、Tukey检验与Student-t检验进行统计学分析，检验水准设为α=0.05。
结果 侵蚀后，所有粘接水门汀的Ra值均升高，U200组与ZnP组的硬度损失百分比最高。经人工唾液浸泡后，仅U200组与ZnP组的Ra值出现显著升高，各组间的硬度损失百分比无显著差异。扫描电子显微镜分析显示，Ketac组与ZnP组的表面粗糙且多孔，U200组的树脂基质降解程度高于ARC组。
结论 可乐饮料介导的侵蚀性暴露会影响所有粘接水门汀的表面特性。