Optical Property Stability of Light-Cured versus Precured CAD-CAM Composites

The aim of this study was to evaluate the optical properties changes after staining of pre-cured (PC) and light-cured (LC) composites. Specimens were prepared using different LC composites (GrandioSO - Voco, Filtek Z350 - 3M/ESPE, Opallis - FGM and Kalore - GC) and four PC composites (Grandio Blocs - Voco, Lava Ultimate - 3M ESPE, Brava Block - FGM and Cerasmart - GC) (n=20). Baseline color, gloss, translucency, and fluorescence were evaluated. Staining protocol was performed for 15 days and the final optical properties were reevaluated. The changes on each property were calculate ($\Delta$ Gloss, $\Delta$ Trauslucency, $\Delta$ Fluorescency, $\Delta\mathbf{E}^{*}00)$. Data were analyzed by ANOVA and Tukey's test $(\alpha=5\%)$. Changes on all properties were observed after staining for all materials, with darkening and reduction of gloss, fluorescence and translucency. Non-significant differences were observed between the light-cured and pre-cured materials of the same manufacturer for the $\Delta\mathrm{G}$ and $\Delta\mathbf{T}$, but significant differences existed for $\Delta \mathbf{F}$ and $\Delta\mathbf{E}^{*}00)$. For $\Delta \mathbf{F}$, the only significant differences were observed between Brava Block and Opallis (smaller). For $\Delta \mathbf{E}^{*}{}_{00}$, only the light-cured composites GrandioSO and Z350 showed significant less change than the corresponding blocks. Pre-cured composites were affected the same way than light-cured ones by the staining in relation to the reduction of gloss and translucency. A higher reduction of fluorescence was observed only for one brand of block and was similar for the others. Two brands the light-cured materials showed less staining, while for the others was similar. The effects of staining vary according to the composite formulation.