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Methods: Three different resin composites were evaluated: Filtek Z250 (Bis-GMA, microhybrid), Filtek Z350 (Bis-GMA, nanofilled) and Filtek P90 (silorane based, microhybrid) (3M-ESPE). For each resin two groups (n=10) of rectangular specimens (15mmX5mmX4mm) were made. After polymerization and polishing, the initial roughness (Ra) was evaluated by the average of three tracings using a roughness tester Hommel T1000 basic. Half of each specimen was protect with nail varnish and one group of each resin was submitted to pH cycling (demineralization-pH 4,3 and remineralization-pH 7,0). For the abrasion test 100.000 strokes of simulated toothbrushing was processed. The protected side was maintained as control. Over the brushed side the final roughness was measured with the same initial parameters and wear was quantified by the average of 3 readings of the real profile between the two surfaces (control and brushed side).
Results: The results (ANOVA, Student “t” test and Tukey, p<0.05) showed significant differences of wear and surface roughness alteration between the materials. Filtek P90 showed the highest wear rate (11.505 ± 5.690μm) compared to Filtek Z250 (4.191 ± 1.725μm) and Filtek Z350 (4.163 ± 0.947μm). The pH cycling significantly affected only the wear of Filtek P90(15.305 ± 5.409 μm). The surface roughness evaluation revealed an increasing on surface roughness for Filtek Z250 and Filtek Z350 after toothbrushing, while Filtek P90 showed an opposite behavior (p<0.05). The scanning electron microscope images were in accordance to the quantitative results obtained.
Conclusions: Silorane based resin showed significant more wear than metacrilate based resin, especially when submitted to pH cycling.
Keywords: Composites, Dental materials, Silorane, Surfaces and Wear