Effect of Flavonoids on Resin Bond Strength Following Tooth Bleaching: A Systematic Review

Abstract

Objective: To evaluate whether application of natural flavonoid-based antioxidants following tooth bleaching would enhance the immediate bond strength of dental adhesives to bleached enamel, through a systematic review of in vitro and in vivo studies.

Materials and methods: A systematic literature search was performed in five electronic databases (Cochrane (CENTRAL), MEDLINE, Scopus, Science Direct and Web of Science) up to from june 2005 to June 2025, available in English language. Studies were selected according to PICOS criteria. Methodological quality was assessed using the Joanna Briggs Institute (JBI) criteria for analytical cross-sectional studies.

Results: A total of 41 studies met the eligibility criteria and were included in the qualitative analysis. The included studies were evaluated a wide range of flavonoids and related plant-derived antioxidants, including grape seed extract (proanthocyanidin), green tea extract (epigallocatechin gallate), quercetin, naringin, cranberry extract, propolis, guava seed extract, strawberry extract, aloe vera, pine bark extract, rosemary extract, and others. Grape seed extract/proanthocyanidin and epigallocatechin gallate (EGCG) showed the most consistent evidence of bond strength restoration to control levels.

Conclusion: The available evidence suggests that the application of flavonoid antioxidants, particularly grape seed extract/proanthocyanidin and EGCG, can restore or significantly improve resin bond strength to bleached enamel, supporting their use to facilitate immediate restorative procedures after bleaching. However, as most evidence is derived from in vitro studies, clinical trials are warranted to confirm these findings.