effect of mechanical loads and surface roughness on wear of silorane and methacrylate-based posterior composites

objectives: dental composite wear in posterior restorations is a concern and is affected by different factors. this study was conducted to evaluate the effect of polishing and mechanical loads on wear of silorane-based and methyl methacrylate-based composites resins. materials and methods: of each dental composite (filtek p90 and filtek p60), 40 samples were fabricated in a polyethylene mold (4mm diameter, 10mm height). according to the finishing and/or polishing protocols (180-grit or 2500-grit silicon carbide papers), the samples of each composite were divided into two groups. surface roughness (rₔ) was measured and recorded using a contact profilometer. the weight of each sample was also measured in grams. the wear test was performed in a pin-on-disc device under two different loads (70n, 150n). afterwards, samples were subjected to profilometry and their weight was measured again. data were analyzed using t-test and univariate anova. p <0.05 was considered statistically significant. results: higher mechanical load resulted in greater weight loss (p<0.001). samples polished with 2500-grit papers showed significantly lower ra changes compared to those polished with 180-grit papers (p<0.001). filtek p90 had greater weight loss than filtek p60 except in one condition (180-grit, 70n). conclusions: results showed that wear of posterior composite restorations depends on mechanical load, type of composite resin and surface properties.