Wear of Bulk-fill Composite Resins after Thermo-mechanical Loading

Abstract

Statement of Problem: Wear of conventional composite resin presented many challenges when restoring posterior teeth and resulted in clinical complications. Bulk-fill composite resins have been proposed as a more suitable and wear-resistant alternative. Objective: To evaluate and compare the volumetric wear (mm3) of bulk-fill composite resins to a conventional composite resin and enamel after thermo-mechanical loading. Methods and Materials: Five composite resins (n=10) were evaluated: four bulk-fill composite resins (Filtek One Bulk Fill [3M Oral Care], Tetric EvoCeram Bulk Fill [Ivoclar Vivadent], Tetric PowerFill [Ivoclar Vivadent], SonicFill 3 [Kerr Corp]); and one conventional composite resin (Filtek Supreme Ultra [3M Oral Care]). Enamel from recently extracted human teeth was used as a control. Specimens were subjected to a 2-body volumetric wear evaluation using a chewing simulator (CS-4.8, Mechatronik). Disc-shaped specimens (10 mm in diameter × 3 mm in thickness) received 500,000 load cycles against steatite antagonists while simultaneously thermocycled (5000 cycles, 5-55°C). Volumetric wear (mm3) was measured using the Geomagic Control X software (3D Systems) based on digital scans of the specimens obtained before and after thermomechanical loading, with a Trios 3 (3Shape) digital scanner. Scanning electron microscopy analysis of wear facets and composite resin filler shape and size was performed. Volumetric wear was statistically analyzed using the one-way ANOVA and Tukey's post-hoc test (α=0.05). Results: All tested composite resins wore at rates significantly higher than enamel (p<0.05). The mean volumetric wear of the composite resins ranged from 1.01 mm3 to 1.48 mm3, while enamel had a mean volumetric wear of 0.25 mm3. Bulkfill composite resins showed higher wear resistance than the conventional composite resin (p<0.05). Conclusions: Bulk-fill composite resins showed higher wear resistance than the conventional composite resin, and both types of composite resin were not as wear-resistant as enamel.