Evaluation of Wear Properties of Four Bulk-Fill Composites: Attrition, Erosion, and Abrasion

Abstract

Purpose. Wear and increased surface roughness are among the reasons for failure of posterior composite restorations. Considering the widespread use of bulk-fill composites in the posterior region, information about their wear resistance is imperative. The aim of this study was to compare the wear and surface roughness of four bulk-fill composite resins with a conventional composite. Methods. Thirty composite discs ( $4\text{mm}\times 10\text{mm}$ ) were fabricated from EverX Posterior (GC), X-tra fil (Voco), Filtek Bulk-Fill Posterior (3M, USA), SonicFill 2 (Kerr), and Z250 (3M) composites. The baseline weight and surface roughness of specimens were measured. For the assessment of the attrition wear, the specimens were placed in a chewing simulator (Mechatronik). pH cycling was performed to erode the composite discs. They were then placed in a tooth brushing simulator machine (Dorsa) for abrasion wear. Finally, the weight and surface roughness of the specimens were measured. Data were compared using one-way ANOVA ( $\text{alpha}\le 0.05$ ). Results. One-way ANOVA showed that the mean weight changes were significant after attrition, abrasion, and erosion ( $P=0.019$ ), but changes in surface roughness were not significant ( $P\ge 0.05$ ). The results of Tukey’s test showed no significant difference between the bulk-fill composites and Z250 regarding weight loss ( $P\ge 0.05$ ), but the weight loss of X-tra fil was significantly greater than that of EverX ( $P=0.007$ ) and Filtek Bulk-Fill ( $P=0.005$ ). Conclusions. Considering the limitations of this study, it appears that the wear and surface roughness of bulk-fill composites are within the acceptable range and are not different from those of a conventional composite.