Change of optical properties of contemporary polychromatic resin composites after light curing and finishing

Objectives: To compare color and translucency changes after light curing and finishing in various shades of five contemporary resin composites. Methods: Light and dark (A1 & A4 or equivalents), enamel (e) and dentin (d), shades were selected from the resin composites Enamel Plus HRi (Micerium), Miris 2 (Coltene), IPS Empress Direct (Ivoclar), Filtek Supreme (3M ESPE) and TPH Spectum (Densply). Ten disc-shaped samples (depth = 10 mm, thickness = 1 mm) per material and shade were fabricated. Three colorimetric readings, over white and black background, according to the CIELab system were taken before and after light polymerization and after finishing with wet carbide papers. Color (ΔE) and translucency (ΔTP) differences were calculated. Results were analyzed by ANOVA, post-hoc Scheffe's test and linear regression analysis. Results: Polymerization provided a wide range of color change, ranging from 1.36 (Hri/UD1) to 8.07 (Miris/WB). Translucency increased in all groups, except Miris/NT. Translucency change varied from -0.4 (Miris/NT) to 8.88 (Hri/UE3). After finishing, ΔE ranged from 0.58 (Hri/ UD4) to 3.41 (Miris/NT). ΔE was significantly positively correlated with ΔL, Δb after curing and with ΔL, Δa, ΔTP after finishing. Conclusions: Polymerization caused remarkable color and translucency changes, which were product and shade dependent. Thirteen out of 18 of the tested resin composites exhibited clinically perceptible (ΔE>2.6) color change after light curing and 2 out of 18 after finishing. Clinical significance: Shade matching with non-polymerized resin composite may be erroneous.