Comparison of translucency between indirect and direct resin composites

Objectives To measure the translucency of indirect and direct resin composites after curing, and to determine the influence of material and shade group combination on these properties. Methods BelleGlass NG (BG, indirect resin composite) and Estelite Sigma (ES, direct resin composite), each composed in three shade groups (EN, OD and TL for BG; BS, AS and OP for ES) of 16 shades were investigated. Resin composite was packed into a mold (BEC) and was cured with a light-curing unit (CWL). Secondary curing was performed in a proprietary curing chamber (CIC) for BG material. Color was measured at the BEC, CWL and CIC conditions in the CIELAB scale using a spectrophotometer. Translucency parameter (TP) was calculated as the color difference between a specimen over a white and a black background. Results TP values before curing were in the range of 7.7 (BG-OD) to 16.9 (ES-AS), and those after curing were in the range of 10.0 (BG-OD) to 21.5 (BG-EN). TP values of both materials were influenced by curing (p < 0.05). There were significant difference in the TP values by the material and shade group combination, and the following homogenous subsets were found based on Tukey multiple comparison test: BG-OD < ES-OP < BG-TL = ES-AS = ES-BS < BG-EN (p < 0.05). Conclusions BG material showed a wider range of TP values than ES, which would improve shade-matching capability of this material. Translucency should be considered when neighboring teeth are treated with different types of resin composites.