Quantification and characterization of nanometer-sized particles released from dental composite products using a multimodal approach

Dental composites are widely used by dentists as restorative material to restore tooth fractures and dental caries or decay. Dental composites often contain advanced nanomaterials. After restoring a tooth, the dentist may use a high-speed handpiece to contour the surface of the composite through the process of drilling, utilizing various dental burs depending on the situation. Additionally, dentists must often remove existing composite restorations for numerous reasons (e.g., recurrent decay or need for a crown). If appropriate controls, such as water aerosol in conjunction with the grinding process and/or local exhaust ventilation, are inadequately utilized, both the dentist and patient may inhale airborne particles released in the drilling process. This study aimed to identify the potential exposure from dental procedures that utilize advanced nanocomposites and to characterize the particles released from commonly used dental composites. To identify the characteristics and elemental composition of the released particles, a uniquely designed nanoparticle sampler, a Sioutas cascade impactor, and real-time instruments were utilized. Both microscopic and size-fractionated concentration analyses confirmed the release of nanometer-sized particles consisting of various metal components that are potentially concerning for human exposure. These results elucidate the potential nanoparticle exposure that may occur during dental practice with advanced materials, based on simulated restoration grinding situations.