Effect of bonding agents used as lubricants on color stability of composite restorations

Abstract

Objective: This in vitro study aimed to evaluate the effect of different bonding agents used as lubricants during composite placement on the color stability of resin-based restorations when exposed to common staining agents over time. Materials and Methods: A total of 120 Tetric EvoCeram composite specimens were prepared and divided into four groups: Control (no lubricant), Scotchbond Universal, Excite F, and Wetting Resin. Each specimen was subjected to staining solutions (water, coffee, or red wine) and stored at 37 °C. Color measurements were recorded using a digital spectrophotometer (VITA Easyshade® V) at baseline, 2 weeks, and 4 weeks, following ISO/TR 28642:2016 guidelines. Color change (ΔE*) was calculated using the CIELAB formula. Statistical analysis was performed using one-way ANOVA, post hoc tests, and paired t-tests (p < 0.05). Results: At 2 weeks, significant differences in ΔE values were observed between groups under coffee staining (p = 0.010), with Wetting Resin showing the lowest discoloration, a followed by Scotchbond Universal and Excite F, while the Control group exhibited the highest color change. Wine caused the highest ΔE values, followed by coffee and water. By 4 weeks, although ΔE values increased in all groups, differences between bonding agents were no longer statistically significant. Time-dependent discoloration was observed across all groups, with the greatest ΔE increases occurring in red wine, followed by coffee and then water. Conclusion: Bonding agents used as lubricants can significantly influence early color stability of composite restorations, particularly under aggressive staining. Wetting Resin provided the best resistance to discoloration, suggesting its potential advantage in esthetically sensitive restorations. However, the protective effect diminishes over time, highlighting the importance of long-term evaluation. Significance: This study suggests that using bonding agents as lubricants during composite placement does not adversely affect color stability and may offer a protective effect under staining conditions. While these findings are limited to in vitro settings, they support the incorporation of this technique with composite restorations.