Biocompatible Multifunctional Polymeric Material for Mineralized Tissue Adhesion

This study develops a biocompatible multifunctional thiol-ene resin system for adhesion to dentin mineralized tissue. Adhesive resins maintain the strength and longevity of dental composite restorations through chemophysical bonding to exposed dentin surfaces after cavity preparations. Monomers of conventional adhesive systems may result in inhomogeneous polymer networks and the release of residual monomers that cause cytotoxicity. In this study, a one-step multifunctional polymeric resin system by incorporating trimethylolpropane triacrylate (TMPTA) and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) is developed to enhance both mechanical properties and adhesion to dentin. Molecular dynamics simulations identify an optimal triacylate:trithiol ratio of 2.5:1, which is consistent with rheological and mechanical tests that yield a storage modulus of ≈30 MPa with or without BMEP. Shear bond tests demonstrate that the addition of BMEP significantly improves dentin adhesion, achieving a shear bond strength of 10.8 MPa, comparable to the commercial primer Clearfil SE Bond. Nanoindentation modulus mapping characterizes the hybrid layer and mechanical gradient of the adhesive resin system. Further, the triacrylate-BMEP resin shows biocompatibility with dental pulp cells and fibroblasts in vitro. These findings suggest that the triacrylate-trithiol crosslinking and chemophysical bonding of BMEP provide enhanced bond strength and biocompatibility for dental applications.