Polyacrylic acid/citrate/amorphous calcium phosphate complex for dentin remineralization and bond durability.

Objective: Dentin bionic remineralization is an effective strategy for enhancing the stability of the resin-dentin bonding interface. Conventional biomimetic mineralization methods still face limitations such as restricted applicability and low mineralization efficiency. Citrate, present at high levels in biological mineralized tissues, plays a significant role in biomineralization. This study prepared polyacrylic acid/citrate/amorphous calcium phosphate complexes (PAA-Cit-ACP) and investigated its ability to promote biomimetic mineralization and improve the stability of the resin-dentin bonding interface.

Methods: Four types of PAA-Cit-ACP complexes, each doped with different contents of citrate (PAA-Cit-ACP-0.5, PAA-Cit-ACP-1, PAA-Cit-ACP-2, and PAA-Cit-ACP-5), were synthesized and characterized. Molecular dynamics simulation was used to clarify the mechanism behind the formation of the PAA-Cit-ACP complexes. Single-layer recombinant collagen fibers and demineralized dentin slices were constructed as mineralization models to validate the mineralization potential of PAA-Cit-ACP. Nanoleakage and in situ zymography were used to evaluate the effect of PAA-Cit-ACP on the durability of resin dentin bonding.

Results: Each group of PAA-Cit-ACP manifested as negatively charged, amorphous spherical nanoparticles with good biocompatibility. After treatment with PAA-Cit-ACP, both single-layer recombinant collagen fibers and demineralized dentin slices demonstrated rapid mineralization, and the resin-dentin bonding interface showed reduced nanoleakage and MMP activity, with PAA-Cit-ACP-1 and PAA-Cit-ACP-2 showing better effectiveness.

Significance: These findings suggest that PAA-Cit-ACP promotes rapid biomimetic remineralization, protecting exposed demineralized collagen fibrils from water- and MMPs-induced degradation, and improving the stability of the hybrid layer.