Estimation of the surface gloss of dental nano composites as a function of color measuring geometry

To estimate the surface gloss of various dental nano composites by using the correlation between deltaE* specular component excluded (SCE) - specular component included (SCI) and surface roughness (Ra).

Two brands of commercial and two experimental light-cured resin composites were used. Resin composite discs were prepared 10 mm in diameter and 3 mm in thickness. 56 subgroups (n=5) were designed according to two different curing conditions (hand light curing and additional post-heat curing) and seven different polishing methods (Mylar, 4000-, 2400-, 1200- and 320- SiC paper, rubber-based silicone, three-step polishing kit). deltaE*SCE-SCI and Ra measurements were done. Two specimens in each subgroup were analyzed by SEM. Multifactorial ANOVA and post hoc Tukey test were applied for the evaluation of the deltaE*SCE-SCI and Ra data (P<0.05). Moreover, Spearman's rank correlation test was used to determine the correlation between deltaE*SCE-SCI and Ra results (P<0.01).

A strong correlation was found between deltaE*(SCE-SCI) and Ra results indicating the surface gloss of the tested composite resin materials after different curing and surface polishing methods. A three-factor interaction was found between curing conditions, surface polishing methods and resin composites (P<0.05) in deltaE*SCE-SCI and Ra results. Additionally, significant differences were found between composites and between polishing methods (P<0.05). Furthermore, there were significant differences between curing conditions in Ra results (P<0.05).