# Quaternary Ammonium Dimethacrylates as an Additive in Dental Composite Resins: A Review of Their Antimicrobial, Mechanical, and Physicochemical Properties

## TL;DR

This paper reviews how adding quaternary ammonium dimethacrylates to dental composites can fight microbes without harming mechanical properties.

## Contribution

The paper provides a critical review of antimicrobial, mechanical, and physicochemical properties of QADMs in dental composites over the past decade.

## Key findings

- QADMs show strong antimicrobial activity against cariogenic and opportunistic pathogens without resistance development.
- QADMs maintain good mechanical and physicochemical properties when added to resin composites.
- Cytotoxicity of QADMs depends on structure and dose, but most are biocompatible at effective concentrations.

## Abstract

Dimethacrylate-based dental materials are dominantly used in restorative procedures for their mechanical and esthetic properties. However, they lack inherent antimicrobial activity, making them susceptible to microbial colonization. This has prompted the development of quaternary ammonium dimethacrylate monomers (QADMs) as a counteractive measure. This review critically assesses the tradeoffs associated with the antimicrobial potential, cytocompatibility, and structural performance of QADMs in the past decade. Across the standardized biological assays studied, QADMs consistently exhibit potent antimicrobial activity against cariogenic and opportunistic pathogens without inducing resistance. QADMs maintain favorable mechanical and physicochemical properties upon incorporation into resin composite formulations. Cytotoxicity is structure- and dose-dependent; nonetheless, most QADMs are biocompatible at antimicrobial concentrations. Notably, quaternary ammonium urethane dimethacrylate monomers (QAUDMAs) offer a balanced combination of antimicrobial and structural properties. Few studies have assessed the long-term mechanical durability of QADM-enhanced composites, leaving clinical relevance inconclusive. Further research is necessary to optimize monomer design and clinically validate these materials.