IADR Abstract Archives
The environmental fate of waste microplastics from resin-based dental composite
Objectives: Resin-based composite restorations have become the ubiquitous alternative to dental amalgam. A trend that is set to continue following the Minimata Convention (signed in 2013), that highlighted the environmental impact of Hg. The fate of the microplastics and the eluted chemicals from resin-based dental composites following clinical finishing regimes is unknown. These are released directly into the urban water sewage system.
Aim: To quantify the potential environmental pollutant effect from the release of microplastics and partly polymerised components of dental composite following clinical finishing regimes.
Methods: Two dental composites (one representative of a current commercially available material and one custom-made calibration composite) containing HEMA, TEGDMA, UDMA and BisGMA, were tested. These composites were polymerised and ground to simulate standard clinical finishing regimes.
The microplastic particulates were stored in tap water and sampled at regular intervals. We measured: (i) the particulate size in solution via laser diffraction analysis; (ii) the concentration and release profiles of the eluted monomers with a combined HPLC and SPME method at trace level concentrations below 20μg/L.
Results: Particulate size was found to be in the range of 1-500μm (mean 289μm). Over 6 months the concentration/elution patterns of the monomers varied. The concentration of all monomers (including residual BPA) spiked in the first 48 hours followed by increased leaching of all monomers into solution over 24 hours to 3 days. A decrease in the leaching of all monomers from 72 hours to 14 days was observed, followed by a relatively large increase at 14 days to 1 month (excluding TEGDMA). This consistent leaching remained for 4 months. BPA is detected throughout the 6 month period. Concentrations of eluates were: HEMA 50-450 ppb, BPA 0-275 ppb, TEGDMA 100-1800 ppb, UDMA 0-3000 ppb, BisGMA 0-150 ppb.
Conclusions: Monomers leached out from particulates at quantifiable levels over a prolonged period of time. Molecular weight, hydrophilicity and diffusion rates of the constituent monomers and high surface area of the particulates contribute to the release patterns observed. This study highlights the need to consider responsible waste management strategies for resin-based dental composite.
Aim: To quantify the potential environmental pollutant effect from the release of microplastics and partly polymerised components of dental composite following clinical finishing regimes.
Methods: Two dental composites (one representative of a current commercially available material and one custom-made calibration composite) containing HEMA, TEGDMA, UDMA and BisGMA, were tested. These composites were polymerised and ground to simulate standard clinical finishing regimes.
The microplastic particulates were stored in tap water and sampled at regular intervals. We measured: (i) the particulate size in solution via laser diffraction analysis; (ii) the concentration and release profiles of the eluted monomers with a combined HPLC and SPME method at trace level concentrations below 20μg/L.
Results: Particulate size was found to be in the range of 1-500μm (mean 289μm). Over 6 months the concentration/elution patterns of the monomers varied. The concentration of all monomers (including residual BPA) spiked in the first 48 hours followed by increased leaching of all monomers into solution over 24 hours to 3 days. A decrease in the leaching of all monomers from 72 hours to 14 days was observed, followed by a relatively large increase at 14 days to 1 month (excluding TEGDMA). This consistent leaching remained for 4 months. BPA is detected throughout the 6 month period. Concentrations of eluates were: HEMA 50-450 ppb, BPA 0-275 ppb, TEGDMA 100-1800 ppb, UDMA 0-3000 ppb, BisGMA 0-150 ppb.
Conclusions: Monomers leached out from particulates at quantifiable levels over a prolonged period of time. Molecular weight, hydrophilicity and diffusion rates of the constituent monomers and high surface area of the particulates contribute to the release patterns observed. This study highlights the need to consider responsible waste management strategies for resin-based dental composite.