Surface properties of universal and flowable nanohybrid composites after simulated tooth brushing

To evaluate gloss and surface roughness (Ra-value) of four universal nanohybrid composites and four flowable nanohybrid composites before and after toothbrush abrasion.

64 dimensionally standardized specimens (n= 8/group) were prepared from four universal nanohybrid composites (i.e. Filtek Supreme XTE Universal, Grandio, Tetric EvoCeram, Venus Diamond) and four flowable nanohybrid composites (i.e. Filtek Supreme XTE Flow, Grandio Flow, Tetric EvoFlow, Venus Diamond Flow). All of the specimens were polished with up to 4000-grit silicon carbide papers. Gloss was measured with a glossmeter and Ra-value was measured with a contact profilometer before and after powered toothbrush abrasion with 70 RDA toothpaste slurry at 12,000 strokes while applying a vertical force of 100 g.

The median gloss values ranged from 80.6 to 93.6 GU before toothbrush abrasion and from 32.8 to 80.0 GU after toothbrush abrasion. The median Ra-value ranged from 0.065 to 0.088 microm before toothbrush abrasion and from 0.076 to 0.277 mirom after toothbrush abrasion. After toothbrush abrasion, Tetric EvoCeram yielded the lowest median gloss value and the highest Ra-value among all eight composites. Filtek Supreme XTE Flowable yielded the highest median gloss value before and after toothbrush abrasion and the lowest Ra-value after toothbrush abrasion. Spearman's rank correlation test revealed that there was negative correlation between the gloss and Ra-value including both before and after toothbrush abrasion (r = -0.681, P < 0.001).