An Anti–saliva contamination Bonding Strategy Based on Polycation Assembly

The high incidence of saliva contamination is a real threat to dentin bonding that underpins contemporary preventive dentistry and clinical dentistry. Saliva contamination can form a nanoscale bacteria-contained adsorption film with high hydration on demineralized dentin matrix (DDM), worsening the insufficient adhesive infiltration into the DDM and causing bacteria load. The resultant bacteria-loaded hybrid layer with more defects aggravates the durability issue of dentin bonding that affects the oral health of billions of people worldwide. To address the issue of saliva contamination, a robust polycation assembly-assisted bonding strategy was developed based on the electrostatic adsorption of bactericidal polycations on the natural template of a 3-dimensional, porous, negatively charged DDM as well as the contaminated DDM to form a stable electrostatic complex via electrostatic adsorption. Both residual bacteria in the biofilm and bacteria from saliva were killed, and the hydrated DDM was dehydrated, causing the release of interface-confined water regardless of the presence of contamination, which greatly improved adhesive infiltration. More interesting, due to the charge reversal caused by polycation adsorption, the polycation/DDM complex actively adsorbed negatively charged saliva proteins continuously and formed a stable polycation/DDM/saliva protein complex, actively erasing the adverse effect of saliva contamination on dentin bonding. This is the first successful construction of a persistently antibacterial and defect-low hybrid layer under saliva contamination.