Cytotoxic effects of composite dust on human bronchial epithelial cells

Abstract

Introduction: Previous research revealed that during routine abrasive procedures like polishing, shaping or removing of composites, high amounts of respirable dust particles (<5μm) including nano-sized particles (<100nm) may be released.

Objective: To determine the cytotoxic potential of composite dust particles on bronchial epithelium cells.

Methods: Composite dust of five commercial composites (one nano-composite, two nano-hybrid and two hybrid composites) was generated following a clinically relevant protocol. Polymerized composite samples were cut with a rough diamond bur (grain size 100μm, speed 200,000rpm) and all composite dust was collected in a sterile chamber. Human bronchial epithelial cells (16HBE14o-) were exposed to serially diluted suspensions of composite dust in cell culture medium at concentrations between 1.1 and 3.3mg/ml. After 24h-exposure, cell viability and membrane integrity were assessed by the WST-1 and the LDH leakage assay, respectively. The release of IL-1β and IL-6 was evaluated. The composite dust particles were characterized by transmission electron microscopy and by dynamic and electrophoretic light scattering.

Results: Neither membrane damage nor release of IL-1β was detected over the complete concentration range. However, metabolic activity gradually declined for concentrations higher than 660μg/ml and the release of IL-6 was reduced when cells were exposed to the highest concentrations of dust.

Significance: Composite dust prepared by conventional dental abrasion methods only affected human bronchial epithelial cells in very high concentrations.

Keywords: Composite dust; Cytotoxicity; Dental composite; Human bronchial cells; Nano-particle; TEM.