Method: Four disc-shaped specimens were fabricated for each composite resin (40%, 50%, 60%, 70% and 75% filler load per weight) and polished with 120-, 220-, 500-, 1200-, 2400- and 4000- grit SiC abrasive paper, respectively. Gloss measurements were made with a glossmeter (Novocurve GlossMeters, NY, USA) prior to simulated toothbrushing. The specimens were subjected to the simulation for 5, 15, 30 and 60 minutes using an electrical toothbrush with a pressure of 2N while being immersed in a toothpaste/artificial saliva slurry. One additional group, made of natural tooth enamel, represented the control group. A SEM observation was performed on one supplementary sample per group in order to evaluate the causes of gloss decrease. Experimental data were analysed by Anova with a significance level of 0.05.
Result: Composite gloss values ranged from 69.7 (40%) to 81.3 (75%) GU (gloss units) at baseline and from 18.1 (40%) to 32.3 (75%) GU after one hour of brushing. Highest gloss values were obtained by 75%-charged resin, while the lowest values were obtained by the 40%-charged one. In contrast to composites, natural enamel maintained its gloss throughout the brushing simulation.
Conclusion: All tested materials showed a similar behavior concerning gloss decrease. However, the more filler a composite resin has the most shiny it appears. Natural enamel performed better than all tested composite resins.