Multifunctional Primer for Dentin Bonding via Biomimetic Mineralization

Enhancing the durability of dentin bonding remains a significant challenge in dental restoration. This study introduces an innovative approach using aldehyde-grafted polyaspartate (PACA) to achieve spatiotemporal regulation of biomimetic mineralization through collagen cross-linking. The collagen cross-linking capability of PACA was confirmed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis. Its ability to induce intrafibrillar mineralization of collagen fibrils was investigated using a rat tail collagen model through dynamic light scattering, zeta potential measurements, and transmission electron microscopy. In addition, the remineralization efficacy of PACA on demineralized dentin collagen was evaluated using scanning electron microscopy, energy dispersive X-ray spectroscopy, and atomic force microscopy. These analyses revealed that PACA facilitates intrafibrillar mineralization by creating an amorphous calcium phosphate–rich microenvironment in the cross-linked region. Subsequently, the mineralization encapsulates the covalently cross-linked polymer and collagen fibrils within a mineralized matrix, forming an organized crystalline structure. Furthermore, PACA was used as a single-component primer in a dentin bonding model, and its impact on bonding durability was assessed through micro-tensile bond strength testing, nanoleakage analysis, and in situ zymography. These assessments demonstrate that PACA could simultaneously achieve collagen cross-linking, matrix metalloproteinase inhibition, and enhanced adhesive penetration while facilitating temporally regulated mineralization. Due to this multifunctionality, the PACA primer significantly improves micro-tensile bond strength and exhibits favorable durability after the aging experiment. This innovative approach provides a promising solution to the durability limitations of conventional adhesive systems.