The effects of toothbrush wear on the surface roughness and gloss of resin composites with various types of matrices

Abstract

Objectives: To evaluate and compare the surface roughness and gloss of a DMA-free composite and a Bis-GMA-free composite with a dimethylacrylate-based composite before and after toothbrush simulation. To evaluate the changes in surface roughness and gloss of the three composite materials after multiple cycles of toothbrushing simulation. Materials and methods: Fifteen dimensionally standardised composite specimens (n=5/ group) from three nano-hybrid resin composites (Tetric EvoCeram, Admira Fusion, and Venus Diamond) were used. The five specimens from each composite material were polished using Sof-Lex discs and subjected to a toothbrushing simulation device. Surface roughness and gloss were measured before toothbrushing and after 5,000, 10,000, 15,000 and 20,000 toothbrushing cycles using a profilometer and a glossmeter respectively. Surface roughness and gloss values were analysed using SPSS, and mean values were compared. Results: For all tested materials, surface roughness increased, and gloss decreased after toothbrushing abrasion. There was no significant cycles-by-material-type interaction (p> 0.05) for surface roughness, but there was a significant cycles-by-material-type interaction (p< 0.05) for gloss. Surface roughness values ranged from 0.14 to 0.22μm at baseline, and increased to between 0.41 and 0.49 μm after 20,000 toothbrushing cycles. Gloss values ranged between 31.9 and 50.6 GU at baseline and between 5.1 and 19.5 GU after 20,000 toothbrushing cycles. The lowest initial Ra value was detected in Venus Diamond, followed by Tetric EvoCeram and then by Admira Fusion. The highest initial gloss value was detected in Tetric EvoCeram, followed by Venus Diamond and then by Admira Fusion. After 20,000 toothbrushing cycles, Admira Fusion had the highest surface roughness values while Venus Diamond had the lowest. Tetric EvoCeram had the highest gloss values while Admira Fusion had the lowest gloss values after 20,000 toothbrushing cycles. Conclusion: Simulated toothbrushing abrasion led to an increase in surface roughness and a decrease in gloss for all tested materials. Venus Diamond had the smoothest surface and Tetric EvoCeram had the glossiest surface after polishing and following 20,000 cycles of toothbrushing abrasion. Admira Fusion demonstrated the roughest surface and had the lowest gloss values before and after toothbrushing abrasion.