Amphiphilic Monomers Enhance Dental Adhesion By Improving Adhesive Penetration

To evaluate the effectiveness of pretreatment with the amphiphilic monomer acryloyl-2-glycine (ACG) in enhancing adhesive penetrability to improve dentin adhesion. ACG was synthesized through the acyl chloride reaction and characterized using infrared spectroscopy (IR) and proton nuclear magnetic resonance (1H NMR). It was dissolved in ethanol at various mass fractions, and its biosafety was assessed with the CCK-8 test. The dentin bonding strength after ACG pretreatment was evaluated with the micro-tensile bond strength (µTBS) test. Additionally, the bonding interface was analyzed using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The ACG monomer was successfully synthesized, and its ethanol solutions at different concentrations demonstrated no significant cytotoxicity. Immediate µTBS results indicated a 23.86% increase in the 10wt% group (43.71±7.10 MPa) and a 33.32% increase in the 15wt% group (47.05±5.10 MPa), with aged groups exhibiting comparable trends. CLSM revealed the deepest fluorescence penetration in the 15wt% group. SEM showed longer and denser resin tags in all experimental groups compared to controls, with the 15wt% group exceeding 200 µm. Furthermore, distinct lateral branches were observed in the 10wt% and 15wt% groups, with thicker tags found in the latter. The amphiphilic monomer ACG pretreatment enhances interfacial hybridization by promoting resin penetration and reducing phase separation, significantly strengthening adhesive-dentin bonding. These findings highlight ACG’s potential to improve the performance of the adhesive-dentin interface in restorative dentistry.