Laboratory evaluation of the effect of toothbrushing on surface gloss of resin composites.

Purpose: To determine changes in surface gloss of different composite materials after laboratory toothbrushing simulation.

Methods: 40 specimens were fabricated for each material (Filtek Supreme XTE, Renamel, Empress Direct, Gradia Direct, Edelweiss, G-aenial, Venus Pearl and Venus Diamond) and polished with 120-, 220-, 500-, 1200-, 2400- and 4000- grit SiC abrasive paper, respectively. Gloss measurements were made with a glossmeter prior to testing procedures and then subjected to simulated toothbrushing for 5, 15, 30 and 60 minutes by means of an electrical toothbrush with a pressure of 2N while being immersed in a 50 RDA toothpaste slurry. Four samples per group were analyzed under SEM immediately after polishing procedures and four samples after 60 minutes simulated toothbrushing in order to evaluate the causes of the gloss decrease. Human enamel was the control group. Statistical analysis was performed using Kruskal Wallis and Tukey's post-hoc test (P < 0.05).

Results: Resin composite initial gloss values ranged from 78.2 to 100.5 at baseline to 13.8 to 62.4 after 1 hour of brushing. Highest gloss values were obtained by Filtek Supreme XTE and Renamel (P < 0.05), followed by Empress Direct. Lowest values were obtained with Venus Diamond, Venus Pearl, G-aenial and Edelweiss. Human enamel was the only material which maintained its gloss throughout the brushing procedure (110.4 after 60 minutes). SEM analysis revealed different patterns of surface degradation dependant on the material.