The effect of different restoration techniques on marginal discoloration in nanohybrid resin composites after immersion in coffee solution

Nanohybrid composite resins are widely used as restorative materials in anterior and posterior teeth. The incremental technique of resin composites is reported to reduce marginal discoloration; however, the effect of re-etching and re-bonding the restoration in order to minimize staining composites remains unclear. Therefore, we aimed to evaluate the effectiveness of the application of the incremental technique along with re-etching and re-bonding on nanohybrid composite restorations after immersion in coffee solution. Twenty-four third molars were divided into four groups where the teeth were restored with nanohybrid composite resins using the incremental (groups I and II) and bulk (groups III and IV) techniques. The re-etching and rebonding technique after finishing was applied to samples in group I. Samples in groups I, II, and III were immersed in coffee solution, whereas those in group IV were immersed in saline (controls). The amount of marginal discoloration was measured in the samples on days 3, 6, and 12. Group I presented with the lowest values of marginal discoloration. Statistically significant (p < 0.05) changes in marginal discoloration were observed on days 6 and 12. In conclusion, incremental technique along with re-etching and re-bonding after finishing is effective in minimizing marginal discoloration in composite resins.