Translucency and Polymerization Ability of Contemporary Resin Composites

Objective: The present study aimed to characterize the translucency and polymerization ability of commercially available contemporary resin composites. Methods: The resin composites considered in this study were Forma (Enamel, Body, and Dentin; Ultradent), Empress Direct (Enamel and Dentin; Ivoclar/Vivadent), Sirius-Z (Enamel and Dentin; DFL), and Orion (Enamel and Dentin; DFL). All photoactivation procedures were performed using the same light source (Valo Cordless, Ultradent, 20 s). The translucency parameter (TP) was determined with a benchtop spectrophotometer (X-Rite, SP60), and the degree of conversion (DC) as a function of thickness was assessed by Fourier transform infrared spectroscopy (FTIR) immediately after photoactivation and again after 1 h. The results were analyzed using analysis of variance (ANOVA) and Tukey’s tests. Pearson’s correlation tests were employed to investigate the relationship between opacity and polymerization ability. Results: Regarding TP, the values obtained among the enamel shades were similar, but a significant variation was observed in dentin shades (p = 0.0023). The degree of conversion (DC) was dependent on the material tested (p = 0.0021 for immediate evaluation and p = 0.0043 for readings taken after 1 h) and the analysis depth (p = 0.0002 for immediate evaluation and p = 0.0038 for readings taken after 1 h). However, the relationship between these two factors was dependent on the time of evaluation. Forma and Empress Direct resin composites exhibited lower polymerization potential for dentin shades. The relationship between opacity and polymerization potential was significant for the baseline evaluation but not significant when considering DC values taken after 1hour. In conclusion, regardless of the brand, enamel shades demonstrated similar TP and curing potential. Conversely, there was a large variation in these parameters for dentin shades. A delayed polymerization can offset slow initial polymerization depending on the resin composite.