Short and long term effects of additional post curing and polishing systems on the color change of dental nano-composites

The purpose was to determine the short and long term effects of polishing systems and post-heat-light curing on the color stability of nano-composites. The disc shaped samples (empty set=10 mm, h=3 mm) were prepared. Forty subgroups (n=5) were designed according to two different curing conditions and five different polishing methods. Color change measurements were performed on the day of specimen preparation (base) and repeated after 1 and 7 months of water storage. MANOVA and Tukey's post hoc tests were applied (p<0.05). While the color difference values of resin composites were ranked as EXP2>EXP1>CME>XTE after 1 month (p<0.05), after 7 months the ranking was EXP2>EXP1>XTE>CME (p<0.05). Type and compositions of nano-composites may be important on the long-term color stability of the restoration. Additional post-heat-light curing of nano-composites may produce higher color change than the hand-light curing protocol. Consequently, the polishing procedures should be applied to obtain more resistant composite surface to discoloration.