in vitro comparison of the effect of aging on discoloration of silorane- and methacrylate-based composite resins

introduction: discoloration of dental composite resins is one of the most common reasons for replacement of these restorations. this in vitro study was carried out to evaluate the effect of aging on discoloration of silorane-based filtek p90 and micro-hybrid z250 composite resins. materials and methods:   this experimental study was carried out on 10 disk-shaped filtek p90 and z250 samples, measuring 9 mm in diameter and 2 mm in thickness. the samples were stored in distilled water for 24 hours after they were prepared for completion of the setting process. initial color measurements were performed with a spectrophotometer. then the samples underwent 384 hours of aging. final color change measurements were then carried out and the results were analyzed with independent-samples t-test and repeated-measures anova (α=0.05).   results: silorane-based composite resin (filtek p90) showed higher δe (14±1.1) in comparison with z250 (10±0.06) (p value < 0.001). the color changes of both composite resins were clinically unacceptable after aging (δe˃3.3). conclusion: under the limitations of the present study, the discoloration of filtek z250 was less than that of filtek p90.