Dental resin composites generate microparticles and impact on gingival keratinocytes-In vitro study

Along with our increased understanding of the spread of microplastic pollution, the awareness of microparticle release from medical and dental materials has increased. Still, their effects on human health are largely unknown. As the use of resin composite materials in dentistry continues to increase, it is essential to understand the formation and biological activities of microparticles generated during material fabrication and use. This study investigated the type and size of microparticles formed from two commonly used restorative resin composite materials, ground with two different dental burs, and their effects on cultured spontaneously immortalized human gingival keratinocytes. Scanning electron microscopy and laser diffraction were used to examine particle morphology and size distribution. Flow cytometry was used to analyze microparticle adhesion to the cell surface and cell viability, and cytokine release was measured. From the two composite materials, microparticles ranging from approximately 4.50 to 137 µm were released. The particles adhered to gingival keratinocytes and induced IL-8 expression of the cells but did not affect the cell viability. The grinding method and the material affected the size of released particles. Further investigation is needed to understand the impact of cellular responses and the dose dependence of the reactions.