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).