Investigating the protective effect of phosphorylated chitosan on dentin collagen fibres at the bonding interface

To investigate the ability of improved phosphorylated chitosan (PC) with or without 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) to crosslink dentin collagen, promote remineralization, and resist collagenase-mediated degradation.

PC was characterized using SEM, ATR-FTIR, and zeta potential analyses. PC, EDC, and PC in combination with EDC were treated with the demineralized dentin surfaces, which were analysed for surface properties, remineralization capacity, and collagenase resistance. Molecular dynamics (MD) simulations were performed to explore mineralization mechanisms.

PC was successfully crosslinked with collagen without altering surface wettability. Untreated samples exhibited collagen collapse under enzymatic attack, whereas the structural integrity of the EDC and PC-EDC groups was maintained. SEM revealed mineralization particles on the PC-EDC surfaces. MD simulations demonstrated the role of collagen as a nucleation site and the stabilization of Ca-P_i clusters by PC.

The PC-EDC system forms covalent collagen bonds, preserves surface properties, accelerates remineralization, and significantly enhances enzymatic resistance. This dual-function strategy addresses collagen degradation and insufficient mineralization, providing a foundation for the development of durable dental adhesives with improved clinical performance.