How universal adhesive systems with nanoencapsulated flavonoids improve long-term bonding to caries-affected dentin

Objectives To evaluate the effect of nano-encapsulated flavonoids in universal adhesives on resin-dentin bond-strength (µTBS) and nanoleakage (NL) on artificial caries-affected dentin (CAD). Materials and Methods Artificial CAD was created on the occlusal dentin surfaces of 60 human third molars by a microbiological assay. Nanoencapsulated quercetin (Q) and naringin (N) were incorporated into Prime&Bond Universal (PBU; Dentsply-Sirona) and Single Bond Universal (SBU, 3M ESPE). The adhesive systems with and without (control) flavonoids were applied to the CAD surface, which was validated by Knoop microhardness (KNH), and a 4-mm resin composite block (TPH Spectrum, Dentsply Sirona) was built up and light-cured. Specimens were sectioned into resin-dentin sticks and tested in tension in a universal testing machine. µTBS and NL tests were performed after 24-h and 6-month water storage (WS). The HL was subjected to micro-raman analysis to detect N and Q. µTBS and NL data were analyzed using a non-parametric three-way repeated measures ANOVA test followed by Bonferroni's test (α = 5%). KNH data was analyzed using a paired Student´s t test. Results CAD exhibited significantly lower KNH values than sound dentin. N and Q nanocapsules increased µTBS and reduced NL values after WS. At 24-h, PBU group showed higher NL values than SBU group, and the values decreased after WS. Q and N were detected within the HL. Conclusions Incorporating nanoencapsulated flavonoids may improve longevity of universal bonding systems applied to CAD. Clinical Relevance: Adhesives restorations with therapeutical compounds might be an option to create stable bonding over time.