IADR Abstract Archives
Environmental Pollution From the Microparticulate Waste of CAD/CAM Resin-based Composite
Objectives: To assess the environmental pollutant risk of the waste from CAD/CAM resin-based composite (RBC) via analytical characterisation of the microparticulates released and monomeric eluates.
Methods: Triplicate samples of microparticulate waste from two CAD/CAM RBCs (CompA and CompB) were prepared and placed in microcosms simulating environmental release scenarios. CompA was a commercially available CAD/CAM RBC and CompB an in-house control standard CAD/CAM RBC, both of which contained all monomers of interest. CompB's monomer concentrations were known. Freshly milled and aged (3 months) CAD/CAM RBC microparticulates were characterized via particle size analysis, Fourier-transform infrared (FT-IR) spectroscopy and potentiometry. Eluted monomers: triethylene glycol dimethylacrylate (TEGDMA), urethane dimethacrylate (UDMA), bisphenol-A glycidyl methacrylate (Bis-GMA), hydroxyethyl methacrylate (HEMA) and bisphenol-A (BPA) were quantified via solid phase micro-extraction coupled with high-performance liquid chromatography.
Results: The potentiometric titrated suspensions of RBC microparticulates exhibited a protonation-deprotonation behaviour over the entire pH range studied. These results indicated that the surface groups capable for potential surface binding are sites involving carboxyl (pK≈3-5), silanol/silica (pK≈6-7), and hydroxyl groups (pK>8). Aged microparticulates exhibited markedly different surface characteristics compared with fresh microparticulates.
The point of zero charge (pHzpc) seen at ≈5-6 indicated microparticulates developed a positive net charge at low pH values and a negative charge at pH7 implying the possibility of electrostatic extraction from solution. Eluted concentrations peaked at day 3 for all monomers in both composites with highest monomer concentrations of BPA (5ppm, CompA) and TEGDMA (13ppm, CompB). After 3 days, all monomers in both composites exhibited low-level constant elution patterns over the entire sampling period (180 days).
Conclusions: Microplastic pollution is an emerging environmental concern. Until now RBC usage has not been considered a microplastic pollution source. Characterisation of RBC microplastic microparticulates and eluates will aid understanding, prevention and remediation of this pollution source and potentially other microplastics outside of dentistry.
Methods: Triplicate samples of microparticulate waste from two CAD/CAM RBCs (CompA and CompB) were prepared and placed in microcosms simulating environmental release scenarios. CompA was a commercially available CAD/CAM RBC and CompB an in-house control standard CAD/CAM RBC, both of which contained all monomers of interest. CompB's monomer concentrations were known. Freshly milled and aged (3 months) CAD/CAM RBC microparticulates were characterized via particle size analysis, Fourier-transform infrared (FT-IR) spectroscopy and potentiometry. Eluted monomers: triethylene glycol dimethylacrylate (TEGDMA), urethane dimethacrylate (UDMA), bisphenol-A glycidyl methacrylate (Bis-GMA), hydroxyethyl methacrylate (HEMA) and bisphenol-A (BPA) were quantified via solid phase micro-extraction coupled with high-performance liquid chromatography.
Results: The potentiometric titrated suspensions of RBC microparticulates exhibited a protonation-deprotonation behaviour over the entire pH range studied. These results indicated that the surface groups capable for potential surface binding are sites involving carboxyl (pK≈3-5), silanol/silica (pK≈6-7), and hydroxyl groups (pK>8). Aged microparticulates exhibited markedly different surface characteristics compared with fresh microparticulates.
The point of zero charge (pHzpc) seen at ≈5-6 indicated microparticulates developed a positive net charge at low pH values and a negative charge at pH7 implying the possibility of electrostatic extraction from solution. Eluted concentrations peaked at day 3 for all monomers in both composites with highest monomer concentrations of BPA (5ppm, CompA) and TEGDMA (13ppm, CompB). After 3 days, all monomers in both composites exhibited low-level constant elution patterns over the entire sampling period (180 days).
Conclusions: Microplastic pollution is an emerging environmental concern. Until now RBC usage has not been considered a microplastic pollution source. Characterisation of RBC microplastic microparticulates and eluates will aid understanding, prevention and remediation of this pollution source and potentially other microplastics outside of dentistry.