Detection of nanoparticles released at finishing of dental composite materials

Abstract

Newly developed dental composite materials contain increased concentrations of filler particles of the nanometer size to produce materials with high mechanical and wear resistance, improved polishability, and long-lasting gloss. With nanocomposites, however, a question arises on possible health risk caused by filler nanoparticles released during finishing and polishing nanocomposite restorations in dental cabinets. As data in the current literature are conflicting, our study was focused on detailed characterization of aerosol particles released during grinding nanocomposites Filtek Ultimate and Estelite Sigma Quick by diamond and tungsten carbide bladed burs. The results were compared with the aerosol particle size obtained from a composite Charisma reinforced with micrometer-size filler particles and an unfilled resin. Using a scanning mobility particle sizer and aerodynamic particle sizer, the release of nano- and micro-sized particles generated during high-speed grinding was detected. The mode of nanoparticle size distribution ranged not only from less than 16.0 to 51.6 nm for both nanocomposites, but also for the microhybrid composite and the unfilled resin. However, the amount of nanoparticles in the aerosol (5.0–68) × 103 cm−3 was not high exceeding 1–8.5 times their background concentration. The release of nanoparticles independently on the filler particle size and their content might suggest that the aerosol nanoparticles may originate from thermal decomposition of composite polymeric matrix due to friction heat rather than from filler nanoparticles. Due to the potential adverse health effects of nanoparticles, more detailed research is needed to investigate the effect of finishing conditions on the nanoparticle generation and their chemical composition to avoid any potential risk to dental staff. A study of the aerosol formed during grinding with water cooling to avoid heating will also be carried out.