The effect of modeling resin on surface microhardness, roughness, and color stability of composite materials depends on the type of resin composite. In clinical practice, the adverse effects of modeling resin might be alleviated by a proper finishing and polishing procedure.

Background:Although most of the studies investigated color stability of different restorative materials, evaluation of color stability of composites after immersion in multiple beverages in the same day by an in vitro oral simulation study is unclear.Objective:To assess color change of different restorative materials at the end of days 1, 14, and 30 of immersion in multiple liquid types to mimic the oral environment in vitro.Method:Ten disc-shaped specimens were made from each of four different resin composites (Filtek Z250, Voco x-tra base, Beautifil Flow Plus, Beautifil II). Baseline color value of each sample was measured using a spectrophotometer. Each composite was respectively immersed in coffee, an orange/pomegranate juice mixture, black tea, and a mouth rinse on the same day to mimic daily liquid consumption of individuals. Color measurements were taken after 1, 14, and 30 days by spectrophotometer and color change values were calculated. Statistical analyses were executed by one-way ANOVA/Tukey HSD and repeated-measures ANOVA.Results:All materials showed significant color change after 1, 14, and 30 days (P < 0.01) of immersion in liquids, with the lowest color alteration observed at the 1st day and the highest observed after the 30th day. Among the materials tested, at each time point (1, 14, and 30 days), the lowest color alteration was detected in Filtek Z250 and the highest color alteration was detected in Beautifil II.Conclusion:Color alteration of composite resins is affected by composite type and storage time. With the exception of 1 day of storage, color changes of all materials were substantial and clinically unacceptable.

Frank and Gilovich (1988) found that teams with black uniforms were penalized by referees more than other teams that did not wear black uniforms in the U.S. National Football League (NFL), and the U.S. National Hockey League (NHL). This finding was examined for the referees in the Turkish Premier Soccer League (TPSL) for the soccer teams wearing or not wearing black uniforms during actual games. 30 male referees' (ages 22-45 years, M = 34.8) decisions were analyzed in a total of 2142 Turkish premier soccer league games played in 7 seasons. Using the number of red and yellow cards and penalty kicks teams drew as a penalty decision criteria, no significant differences were found between Turkish soccer teams wearing black uniforms or those not and the number of penalty kicks. This result, which was different from that of Frank and Gilovich's work, was discussed in relation to the social psychological point of view of different cultures and societies.

Objectives:The aim of this study was to evaluate the effects of time elapsed since bleaching and different bleaching regimens on the microtensile bond strength of resin composite to enamel.Methodology:Forty flattened buccal enamel surfaces were divided into four groups: An unbleached (control) group and three bleaching groups. Control group specimens were not subjected to a bleaching regimen (Group 1), while those in the bleaching groups were bleached as follows: opalescence 10% (Group 2), whiteness perfect 16% (Group 3), and whiteness hydrogen peroxide 35% (Group 4). Thereafter, the bleached specimens were divided into three subgroups (n = 4 teeth each) for restoration according to predetermined posttreatment time intervals (immediately, 1 week, and 2 weeks). Bonded specimens were then sectioned and subjected to μTBS testing. The data were analyzed using Kruskal–Wallis and Mann–Whitney U-tests at α = 0.05.Results:There was a significant difference in the μTBS of the resin composite to enamel in groups that were bonded immediately after bleaching and in the control group (P < 0.05). Compared to the control group, the μTBS in Groups 2, 3, and 4 decreased significantly 1-week postbleaching (P < 0.05). No significant difference in μTBS was observed between the bleached and unbleached groups 2 weeks after treatment (P > 0.05).Conclusions:Adhesive restorative procedures could not be performed immediately or after 1 week irrespective of the type or concentration of bleaching system used. Composite restorations on bleached enamel surfaces should be performed after an interval of at least 2 weeks.