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Background: Adhesive monomers are not able to fully encapsulate collagen fibrils in hybrid layer leaving them vulnerable to time-dependent hydrolytic degradation. The current in vitro study was designed for investigation of the remineralization of the resin-dentin hybrid layer using biomimetic analogs by nanoleakage investigation., Material and Methods: Firstly, occlusal enamel of thirty human molars was removed exposing flat surface of dentin, then randomly divided into three main groups according to the different remineralizing protocols (n=10) (R): control group (R0), STMP group (R1), and biomimetic remineralizing group (R2). The dentin surface of the STMP and biomimetic remineralizing groups (R1 and R2) was treated with STMP solution, followed by self-etch adhesive application on dentin surface of all groups, and restored with double 2-mm thick layers of resin composite. Each tooth was sectioned perpendicularly to the resin-dentin interface for producing 1-mm thick slaps. Each group was subdivided into four subgroups according to the incubation time to 24 hours, one month, three months, and 4 months. Retrieved slabs were prepared for nanoleakage for evaluation of metallic silver particles distribution percentage at the resin-dentin interface using digital image analysis software., Results: There was a statistically significant increase in nanoleakage over time in all three groups. However, the third group showed the least increase in metallic silver uptake over time., Conclusions: Hybrid layer could be remineralized by using dual-biomimetic analogs (PAA and STMP). Key words: Hybrid layer, remineralization, nanoleakage, polyacrylic acid, sodium trimetaphosphate., Competing Interests: Conflicts of interest There are no conflicts of interest., (Copyright: © 2022 Medicina Oral S.L.)

This study investigated the effect of phytic acid (IP6) in different concentrations and application times on microtensile bond strength (µTBS) and interfacial integrity of universal adhesive to deep dentin. Flat deep dentin surfaces of 48 human molars were either etched with 37% phosphoric acid (PA) for 15 sec (control); or received no acid treatment and universal adhesive was applied directly in a self-etch mode (SE); or divided according to IP6 concentration (C) into two main groups: C1, 0.5%, and C2, 1%. Specimens of IP6 groups were further subdivided into three subgroups according to application time of IP6 (T) where; T1, 15 sec; T2, 30 sec and T3, 60 sec. Single Bond Universal Adhesive was then applied and resin composite blocks were built-up. Forty Specimens were then sectioned to produce resin/dentin beams that were used for µTBS testing using a universal testing machine. The remaining eight specimens were sectioned into slabs that were immersed into ammonical silver nitrate solution and nanoleakage was observed using a field emission scanning electron microscope (FE-SEM). The results showed that the application of IP6 in 0.5% and 1% produced significantly higher µTBS and less nanoleakage compared to PA and SE groups. Also, the application of IP6 for 60 sec recorded the highest µTBS and the lowest nanoleakage followed by 30 sec, and 15 sec respectively. Therefore, conditioning of deep dentin with IP6 enhances µTBS and interfacial integrity of universal adhesive to deep dentin in comparison to PA etching or using the universal adhesive in SE mode.