Photodynamically crosslinked and chitosan-incorporated dentin collagen.

A lingering concern with restored root-filled teeth is the loss of structural integrity of the dentin and dentin-sealer interface over time. We hypothesized that crosslinking of dentin collagen with simultaneous incorporation of a biopolymer into collagen matrix would improve its structural stability. This study aimed to investigate the effects of combining chemical/photodynamic crosslinking of dentin collagen with the incorporation of carboxymethyl-chitosan (CMCS) on the resistance to enzymatic degradation and mechanical properties of dentin collagen. Ninety-six demineralized dentin collagen specimens (human, n = 72; and bovine, n = 24) were prepared and crosslinked chemically/ photodynamically, with/without CMCS. Glutaraldehyde and carbodiimides were used for chemical crosslinking, while rose Bengal activated with a non-coherent light (540 nm) at 20 J/cm(2) was applied for photodynamic crosslinking. The crosslinked human dentin collagen was subjected to chemical characterization, 7 days enzymatic degradation, and transmission electron microscopy (TEM), while the bovine dentin collagen was used for tensile-testing. Crosslinked collagen showed significantly higher resistance to enzymatic degradation (p < 0.01), stable ultrastructure, and increased tensile strength (p < 0.05). Crosslinking CMCS with collagen matrix as observed in the TEM further improved the mechanical properties of dentin collagen (p < 0.01). This study highlighted the possibility of improving the resistance and toughness of dentin collagen by chemically/photodynamically crosslinking collagen matrix with CMCS.