The effect of stain solution and curing units on the color stability of nano composite resins

The aim of this research was to study the effect of two light curing units on the color stability of nano composite resins, as a function of accelerated aging from stain exposure. Two aesthetic light-cured nanocomposite resins (Filtek & Grandio) were cured in polytetrafluoroethylene disc ring (30 each) using two different light-curing units, QTH and PAC. Two beverages (coffee and tea) were used as staining solutions and distilled water was used as a control. The evaluation was made after 1, 7 and 30 days by means of reflectance spectrophotometry. The data were subjected to statistical analysis using one-way ANOVA and post hoc comparison was made using the Tukey test with level of significance of 5%. Krushal-Wallis Multiple Comparison test was performed to evaluate the D E between tea and coffee immersion and water experienced by the two tested nano composite resins .The results showed that there was a Statistical differences between tea and water and tea and coffee at different tested periods; whereas no statistical difference was observed between water and tea for the PAC cured Grandio resin specimens after 1 day immersion period. In conclusion, the PAC cured Grandio resin specimens showed significantly higher discoloration than the other specimens immersed in the tested staining solutions if compared with control.. Nanocomposite resin with lower filler contents (Filtek) was resistant to discoloration over a longer immersion period. Clinical significance: It may be considered prudent for the dentist to avoid the use of PAC curing light for nanocomposite restorations in heavy coffee drinks and it may also be preferable to use high power QTH curing light and composite with lower filler contents.King Saud Universit