Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 13 2 2016 10 10 92 100 EN Mehdi Shirinzad Associate Professor, Department of Operative Dentistry, Dental School, Hamadan University of Medical Sciences, Hamadan, Iran Loghman Rezaei-Soufi Associate Professor, Dental Research Center, Department of Operative Dentistry, Dental School, Hamadan University of Medical Sciences, Hamadan, Iran Maryam Sadat Mirtorabi Specialist in Operative Dentistry, Gorgan, Iran Farshid Vahatinia Student of Dentistry , Dental School, Hamadan University of Medical Sciences, Hamadan, Iran 2015 12 04 2016 07 10 Objectives: Composite restorations must have tooth-like optical properties namely color and translucency and maintain them for a long time. This study aimed to compare the effect of accelerated artificial aging (AAA) on the translucency of three methacrylate-based composites (Filtek Z250, Filtek Z250XT and Filtek Z350XT) and one silorane-based composite resin (Filtek P90). Materials and Methods: For this in vitro study, 56 composite discs were fabricated (n=14 for each group). Using scanning spectrophotometer, CIE L*a*b* parameters and translucency of each specimen were measured at 24 hours and after AAA for 384 hours. Data were analyzed using one-way ANOVA, Tukey’s test and paired t-test at P=0.05 level of significance. Results: The mean (±standard deviation) translucency parameter for Filtek Z250, Filtek Z250XT, Filtek Z350XT and Filtek P90 was 5.67±0.64, 4.59±0.77, 7.87±0.82 and 4.21±0.71 before AAA and 4.25±0.615, 3.53±0.73, 5.94±0.57 and 4.12±0.54 after AAA, respectively. After aging, the translucency of methacrylate-based composites decreased significantly (P<0.05). However, the translucency of Filtek P90 did not change significantly (P>0.05). Conclusions: The AAA significantly decreased the translucency of methacrylate-based composites (Filtek Z250, Filtek Z250XT and Filtek Z350XT) but no change occurred in the translucency of Filtek P90 silorane-based composite. Keywords: Composite Resins; Silorane Resins; Methacrylates https://fid.tums.ac.ir/index.php/fid/article/view/932 https://fid.tums.ac.ir/index.php/fid/article/download/932/881