Mussel-Inspired Etchant with Catechol-Lys-Methacrylate for Bond Durability

Resin-dentin bonding technology is the primary method for tooth restoration in clinical practice. However, the formation of a defect zone at the bonding interface due to inadequate moisture control at the interface remains a major challenge. Inspired by mussel wet-adhesion mechanisms, this study functionalized phosphoric acid etchants with catechol-lysine-methacrylate (CLM), a polymerizable small-molecule monomer. During dentin demineralization, catechol binding to demineralized dentin was confirmed using an incubation-rinsing technique, while lysine's role in facilitating rapid water release at the bonding interface was validated by freeze-drying mass loss, surface charge distribution, and thermogravimetric analysis. Confocal laser scanning microscopy revealed increased resin tag lengths in the CLM-treated groups, indicating enhanced resin infiltration. Ultimate tensile strength, dry mass loss, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and in situ zymography demonstrated catechol-enabled collagen stabilization via Schiff base/ester bonds and endogenous enzyme inhibition. Micro-tensile testing revealed that the 4- to 5-mg/mL CLM groups maintained bond strength after 10,000 thermal cycles. Thus, CLM-functionalized etchants may enhance bonding durability in vitro by improving moisture control and collagen stability.