IADR Abstract Archives
Dental Monomer Release From Respirable Fraction of Composite Dust
Objectives: To determine whether respirable composite dust may release monomers in the respiratory tract.
Methods: Composite sticks of four commercial dental composites (Filtek Supreme XTE, Z100 MP, Grandio, Gradia Direct) were prepared using a metal mold (17.4x5.4x1.6mm) and subsequently light-cured for 20sec (output >1000mW/cm2). Entire blocks were then ground in an enclosed plexiglass chamber (270x270x420mm), with a rough dental bur (grain size 100µm, speed 200,000rpm). Airborne respirable dust was collected using a personal cyclone holding a cassette with a teflon filter (pore size 5µm) connected to a personal pump. Immediately after particle collection, the filter was removed from the cassette and transferred to a glass vial containing 1ml of extraction solvent (ethanol or water) and subsequently rotated for 24h in an overhead rotator. The amount of released monomers (BisEMA, BisGMA, UDMA, TEGDMA) and Bisphenol A was measured with liquid chromatography mass spectroscopy (LC-MS/MS). Characterization of the dust collected on the filters in the cyclone was done by transmission electron microscopy (TEM) and by energy dispersive spectroscopy (EDS).
Results: Ultra-morphological analysis of the respirable particles by TEM showed that most particles were nano-sized, although their size ranged between 6nm and 5µm with a mode value between 12 and 39nm. Elemental analysis by TEM-EDS proved that the particles collected on the filters originated from the dental composites. LC-MS/MS analysis revealed that, irrespective of the type of composite, the respirable fraction of composite dust may release relatively high concentrations of unpolymerized methacrylate monomers, both in water and ethanol.
Conclusions: Resin-coated nano-sized particles could function as a vehicle to transport monomers deeply into the lungs.
Methods: Composite sticks of four commercial dental composites (Filtek Supreme XTE, Z100 MP, Grandio, Gradia Direct) were prepared using a metal mold (17.4x5.4x1.6mm) and subsequently light-cured for 20sec (output >1000mW/cm2). Entire blocks were then ground in an enclosed plexiglass chamber (270x270x420mm), with a rough dental bur (grain size 100µm, speed 200,000rpm). Airborne respirable dust was collected using a personal cyclone holding a cassette with a teflon filter (pore size 5µm) connected to a personal pump. Immediately after particle collection, the filter was removed from the cassette and transferred to a glass vial containing 1ml of extraction solvent (ethanol or water) and subsequently rotated for 24h in an overhead rotator. The amount of released monomers (BisEMA, BisGMA, UDMA, TEGDMA) and Bisphenol A was measured with liquid chromatography mass spectroscopy (LC-MS/MS). Characterization of the dust collected on the filters in the cyclone was done by transmission electron microscopy (TEM) and by energy dispersive spectroscopy (EDS).
Results: Ultra-morphological analysis of the respirable particles by TEM showed that most particles were nano-sized, although their size ranged between 6nm and 5µm with a mode value between 12 and 39nm. Elemental analysis by TEM-EDS proved that the particles collected on the filters originated from the dental composites. LC-MS/MS analysis revealed that, irrespective of the type of composite, the respirable fraction of composite dust may release relatively high concentrations of unpolymerized methacrylate monomers, both in water and ethanol.
Conclusions: Resin-coated nano-sized particles could function as a vehicle to transport monomers deeply into the lungs.