Monomer With Dual-Chemical Bonding To Dentin Enhances Bonding Durability

To enhance the long-term stability of light-cured composite resin restorations, this study developed a silane-modified polyurethane acrylate (SPUA) monomer to create a novel etch-and-rise adhesive without primer pretreatment. SPUA establishes dual chemical bonds with dentin hydroxyapatite (HAP) and collagen, aiming to improve bond strength, crosslinking density, hydrolysis resistance, and interfacial stress buffering. SPUA was synthesized via solution polymerization, with structural characterization via FTIR, NMR, and GPC. Interactions between SPUA and HAP/collagen were analyzed using FT-IR, XPS, SEM, and TEM. The adhesive's physicochemical properties (viscosity, double-bond conversion, water sorption) and mechanical performance (thermal stability, tensile strength) were evaluated. Bonding efficacy was assessed through micro-tensile bond strength, nano-leakage, and biocompatibility tests. SPUA formed dual chemical bonds with HAP and collagen (via hydroxyl group). The optimized adhesive (SPUA3) achieved an immediate bond strength of 42.92 MPa (71.75% higher than Bis-GMA controls) and post-aging strength of 31.57 MPa (55.67% higher). It demonstrated superior hydrolysis resistance, stress-absorbing capability, and biocompatibility. The SPUA-based adhesive significantly enhanced hybrid layer quality through dual chemical bonding, high crosslinking, and elastic stress buffering, effectively mitigating interfacial degradation. This strategy addresses key challenges in resin-dentin bonding, including water penetration, multi-stress effects, and insufficient chemical interactions, offering a promising approach to prolonging restoration longevity. The study provides theoretical and practical foundations for advancing dentin bonding technologies.