A novel dual-reactive primer enhances bond durability and builds chemical interlocking structures at the caries-affected dentin-biomaterial interface.

Dental caries remains a major challenge in clinical dentistry, with successful resin restoration relying on the formation of a durable dentin-resin interface. In minimally invasive dentistry (MID), caries-affected dentin (CAD) is routinely preserved and often becomes the primary bonding substrate. However, bonding to CAD is suboptimal, and current strategies to improve this interface are limited. Here, we present a novel bonding strategy based on a dual-reactive functional monomer, ITCM, in combination with pretreatment application techniques. A simple 5-s ITCM pretreatment significantly enhanced both immediate and aged bond strength to CAD. Acting as a "molecular bridge", ITCM bridges hydrophilic CAD layer with hydrophobic adhesive layer, facilitating the formation of a chemical interlocking structure, increasing CAD surface energy, and promoting deep adhesive infiltration. In addition, ITCM improves collagen enzymatic resistance and functions as a non-zinc-binding inhibitor of MMPs. Biocompatibility assessments demonstrated acceptable in vitro and in vivo safety, supporting its clinical potential. This study addresses a critical challenge in dentistry by introducing a chemical bonding strategy tailored to CAD. The ITCM pretreatment strategy provides a foundation for next-generation adhesives aimed at reinforcing the CAD-resin interface, extending restoration longevity, and preventing secondary caries.