Effect of Different Light-Curing Modes on Degree of Conversion, Staining Susceptibility and Stain's Retention Using Different Beverages in a Nanofilled Composite Resin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Statement of Problem:It is unknown whether the staining pigment concentration would affect the color of composite resin and whether the absorption of the staining pigment is related to the degree of conversion (DC).Purpose:The purpose of this study was to evaluate the effect of light-curing units (LCUs) on DC, superficial staining (Delta E), and pigment concentration (PC) in a nanofilled composite resin (Z350, 3M ESPE) using different beverages.Materials and Methods:Specimens were polymerized for 20 seconds using four LCUs (N = 50): quartz-tungsten-halogen (QTH)-450 mW/cm2; laser (LAS)-300 mW/cm2; second-generation light-emitting diode (LED)-1100 mW/cm2; and third generation LED-700 mW/cm2. DC (%) was measured using Fourier transform infrared spectroscopy. Specimens concerning each group (N = 10) were then immersed in one of the solutions (distilled water, red wine, whisky, coffee, and cola-40 min/day, for 40 days). Specimen's color was measured before and after exposure to solutions using a colorimeter (Commission Internacionale de I'Eclairaga L* a* b* color scale), and Delta E was calculated. Specimens were then prepared for the spectrophotometric analysis to measure PC. Data were submitted to two-way analysis of variance and Tukey's test (p = 0.05).Results:DC: QTH presented the lowest DC, with statistical differences for LAS, LED 2, and LED 3. Whisky and wine showed lower PC mean values than cola and coffee. No statistical difference was observed for LCUs regarding PC and all staining solutions, except cola. Whisky showed the highest values for Delta E regarding all LCUs. Wine showed statistically lower Delta E than whisky, with water presenting the lowest Delta E. LAS and QTH showed higher values than LED 2 concerning Delta E.Conclusion:LCUs interfered with DC and altered the PC and Delta E of the composite resin submitted to different staining solutions. There was no correlation among DC, PC, and Delta E.CLINICAL SIGNIFICANCELight-curing modes might interfere with staining susceptibility, stain's retention, and DC of a composite resin, compromising the clinical performance. The highest pigment absorption was not associated with the highest superficial staining of the composite resin. Alcoholic drinks lead to greater superficial staining and non-alcoholic solutions lead to a higher pigment concentration.(J Esthet Restor Dent 23:106-115, 2011).