Surface roughness and wear of resin cements after toothbrush abrasion

Increased surface roughness and wear of resin cements may cause failure of indirect restorations. The aim of this study was to evaluate quantitatively the surface roughness change and the vertical wear of four resin cements subjected to mechanical toothbrushing abrasion. Ten rectangular specimens (15 × 5 × 4 mm) were fabricated according to manufacturer instructions for each group (n = 10): Nexus 3, Kerr (NX3); RelyX ARC, 3M ESPE (ARC); RelyX U100, 3M ESPE (U100); and Variolink II, Ivoclar/Vivadent (VL2). Initial roughness (Ra, µm) was obtained through 5 readings with a roughness meter. Specimens were then subjected to toothbrushing abrasion (100,000 cycles), and further evaluation was conducted for final roughness. Vertical wear (µm) was quantified by 3 readings of the real profile between control and brushed surfaces. Data were subjected to analysis of variance, followed by Tukey’s test (p < 0.05). The Pearson correlation test was performed between the surface roughness change and wear (p < 0.05). The mean values of initial/final roughness (Ra, µm)/wear (µm) were as follows: NX3 (0.078/0.127/23.175); ARC (0.086/0.246/20.263); U100 (0.296/0.589/16.952); and VL2 (0.313/0.512/22.876). Toothbrushing abrasion increased surface roughness and wear of all resin cements tested, although no correlation was found between those variables. Vertical wear was similar among groups; however, it was considered high and may lead to gap formation in indirect restorations.

树脂水门汀的表面粗糙度提升与磨耗加剧，可能导致间接修复体失效。本研究旨在定量评估四种经机械牙刷磨耗处理的树脂水门汀的表面粗糙度变化与垂直磨耗量。本研究每组设置10个矩形试样（尺寸为15×5×4 mm），依照厂商说明书制备试样（n=10），受试树脂水门汀分别为：Kerr公司的Nexus 3（NX3）、3M ESPE公司的RelyX ARC（ARC）与RelyX U100（U100），以及Ivoclar/Vivadent公司的Variolink II（VL2）。使用粗糙度仪进行5次读数，以获取试样的初始表面粗糙度（Ra，单位：μm）。随后将试样置于牙刷磨耗试验机中进行10万次循环磨耗处理，并再次检测其最终表面粗糙度。通过对比对照组与磨耗组试样的真实轮廓，进行3次读数以量化垂直磨耗量（单位：μm）。采用方差分析对数据进行处理，随后辅以图基多重比较检验（显著性水平设为p<0.05）。针对表面粗糙度变化量与磨耗量进行皮尔逊相关性检验（p<0.05）。各组试样的初始/最终表面粗糙度（Ra，μm）与垂直磨耗量（μm）均值如下：NX3：0.078/0.127/23.175；ARC：0.086/0.246/20.263；U100：0.296/0.589/16.952；VL2：0.313/0.512/22.876。经牙刷磨耗处理后，所有受试树脂水门汀的表面粗糙度与磨耗量均显著升高，但二者未发现显著相关性。各组间垂直磨耗量无显著差异，但磨耗程度较高，可能引发间接修复体出现间隙。