Influence of coffee on reflectance and chemistry of resin composite protected by surface sealant

Abstract

Purpose: To assess the influence of the light-curing unit type and whether or not it was worth using surface sealant protection on resin composite restorative materials stained by coffee. Another objective was to propose the monitoring of coffee staining by FT-Raman spectroscopy using carbon-hydrogen (C-H) bonds as reference to the composite matrix degradation.

Methods: Sixty cylindrical specimens of resin composite were prepared and divided into six groups: HC (control)--cured with a halogen light; LC (control) cured with a LED; HF--cured with a halogen light + Fortify Plus; LF--cured with a LED + Fortify Plus; HP--cured with a halogen light + PermaSeal; LP--cured with a LED + PermaSeal. After storage for 24 hours at 37% and 100% of relative humidity, the top surface was protected, and the other surfaces isolated. Polishing with paper discs was performed after 24 hours of curing and prior to FT-Raman spectroscopy and reflectance measurements. All specimens were submitted to coffee staining for 14 days and evaluated by both systems. Results were statistically analyzed by ANOVA and Tukey tests.

Results: FT-Raman spectrum only showed significant changes in groups LC and LP (P< 0.05). Reflectance demonstrated that staining was present in all specimens protected by sealants. Sealant staining was larger in the HF (P < 0.001) group.