# Physicochemical and Mechanical Performance of Dental Resins Formulated from Dimethacrylated Oligoesters Derived from PET Recycling via Glycolysis

## TL;DR

This study explores using recycled PET materials to create safer and more sustainable dental resins with better water resistance and lower BPA release.

## Contribution

The study introduces a novel dental resin formulation from recycled PET, offering reduced BPA release and improved water resistance.

## Key findings

- PET-GLY-DM resins showed higher degree of conversion and increased polymerization shrinkage compared to traditional formulations.
- PET-GLY-DM resins exhibited significantly lower water sorption and improved long-term mechanical performance after water immersion.
- PET-GLY-DM resins demonstrated low BPA release, making them a safer alternative to conventional dental resins.

## Abstract

Growing concerns over the toxicity and sustainability of dental materials have driven the search for alternatives to bisphenol A-glycidyl methacrylate (Bis-GMA), a widely used dental resin monomer associated with health risks. This study highlights the potential of less health-hazardous dental formulations by incorporating high-value materials derived from the glycolysis of poly(ethylene terephthalate) (PET). Dimethacrylated oligoesters (PET-GLY-DM), synthesized through the methacrylation of PET glycolysis products, were blended with Bis-GMA and triethylene glycol dimethacrylate (TEGDMA), toward the gradual replacement of Bis-GMA content. The innovative PET-GLY-DM-based resins exhibited a higher degree of conversion compared to traditional Bis-GMA/TEGDMA formulations, as measured by FTIR spectroscopy, accompanied by an increase in polymerization shrinkage, evaluated via a linear variable displacement transducer system. While the incorporation of PET-GLY-DM slightly reduced flexural strength and elastic modulus, it significantly decreased water sorption, resulting in a smaller reduction in mechanical properties after water immersion for 7 days at 37 °C and improved long-term performance. Furthermore, PET-GLY-DM resins exhibited low bisphenol-A (BPA) release measured with HPLC. It was thus confirmed that PET-GLY-DM resins derived from the glycolysis of PET wastes represent a promising alternative to conventional light-cured dental resins, offering reduced BPA release and improved water resistance.