Advancing universal dental adhesives: Biomimetic strategies for enhanced hybrid layer remineralisation and bond durability

Abstract Resin–dentine bonds degrade when water‐rich, resin‐sparse collagen persists within the hybrid layer. This study evaluated biomimetic remineralisation strategies that aimed to enhance adhesive durability: polyacrylic acid–stabilised amorphous calcium phosphate–loaded mesoporous silica nanoparticles (PA–ACP/MSN) incorporated at 15 vol% into the primer phases of two commercially available two‐step universal adhesives (G2 Bond Universal and OptiBond eXTRa Universal) applied in etch‐and‐rinse mode, with or without phosphorylation pretreatment (5% PA + 5% sodium trimetaphosphate). Adhesive‐dentine specimens were characterised using microtensile bond strength (µTBS), confocal Raman microscopy (Phosphate peaks; Resin CH 2 peaks; Mineral–Matrix ratio MMR), nanoindentation across the hybrid layer and dye‐assisted micropermeability assays. The incorporation of PA–ACP/MSN did not adversely affect the immediate µTBS of either adhesive. After ageing, the biomimetic treatment group demonstrated enhanced phosphate content, improved micro‐mechanical properties, preservation of resin characteristics, a higher elastic modulus across the hybrid layer and a marked reduction in permeability relative to the control group. Adding the phosphorylation pretreatment step conferred no additional benefit over PA–ACP/MSN alone. These findings indicated that embedding PA–ACP/MSN in universal‐adhesive primers promoted remineralisation, stiffened and sealed the hybrid layer, and preserved bonding effectiveness without adding clinical complexity, supporting a practical path to durable, bioactive/biomimetic resin–dentine interfaces.