Development of Functional and Hydrolytically Stable Vinyl Monomers as Methacrylate Dental Resin Restorative Alternatives

Current methacrylate (MA)-based dental resin-based restoratives (RBRs) are susceptible to hydrolysis, catalyzed by oral salivary, bacterial, and host immune system derived enzymes, limiting their service-lives in vivo. This work presents a feasible alternative resin system that can be used for improving the clinical service life of restorative materials while not compromising fundamental physical and mechanical properties of contemporary MA-based systems.

Abstract

Dental resin-based restorative (RBR) materials represent the most ubiquitous biomaterials utilized globally. Methacrylate (MA)-ester based monomers – present in RBRs since the 1960s – experience significantly elevated rates of failure compared to previously used silver/amalgam fillings attributed to their hydrolysis reported in both simulated and in vivo environments. There is currently no alternative RBR chemistry that matches the functional and clinical workflow considerations of MA-RBRs while addressing their limited-service lives. The objective of this work is to utilize a systematic framework to develop alternative hydrolytically-stable monomers (HSMs), assessing key physical properties, biostability, and cytocompatibility towards eliminating or reducing the biodegradation of RBRs. This process yielded HSMs (referreed to as 3BE, 3TE) that matched the physical properties of MA-control materials, including viscosity, polymerization conversion, hydrophilicity, water uptake, and surface hardness (p > 0.05), while outperforming MA-based materials in all simulated oral environments, showing improved biostability in reconstituted human saliva, simulated human salivary esterase (SHSE), bacterial culture, and acidic media (p < 0.05). Additionally, HSMs were found to be less cytotoxic than commercial MA-monomers (p < 0.05) and unlikely to be genotoxic. Therefore, the HSMs and associated resins developed in this study have the potential to significantly improve the clinical service life of RBRs, without compromising their fundamental features.