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Published on: November 9, 2014
Effect of dental composite dust on human gingival keratinocytes
Sabrina Himmelsbach1, Thorsten Steinberg2, Pascal Tomakidi2
1Department of Operative Dentistry and Periodontology, Center for Dental Medicine, Faculty of Medicine, Medical Center - University of Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany; Department of Oral Biotechnology, Center for Dental Medicine, Faculty of Medicine, Medical Center - University of Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany.
Objective:
The aim was to investigate the effect of particles released during grinding of dental composites on human gingival keratinocytes (HGK).
Methods:
Specimens from Filtek™ Supreme XTE and ceram.x® universal were prepared and ground to dust. The dust was filtered (≤ 5 µm) and the particle size distribution was examined using NANO-flex®-180° dynamic light scattering (DLS). Suspensions at five concentrations (3, 10, 30, 100 and 300 µg/mL) were prepared using keratinocyte growth medium (KGM). These suspensions, as well as a positive (CuO) and a negative control (KGM) were added to HGK. The cells treated with Filtek™ Supreme XTE suspensions were analyzed by real-time monitoring using RTCA iCELLigence™. In addition, light and scanning electron microscopic images of the exposed cells were taken. Indirect immunofluorescence staining was performed to detect the extracellular matrix protein fibronectin.
Results:
In distilled water, DLS showed similar particles' range (171.9 nm- 2.7 µm) for both composites. In saliva, larger particles were detected (Filtek™ Supreme XTE: 243 nm-6,5 µm; ceram.x® universal: 204 nm- 4,6 µm). iCELLigence™ revealed similar results of cell growth parameters for HGK incubated with composite dust (≤ 5 µm) at different concentrations. The microscopic images indicated unaltered cell structures and formation of large agglomerates with high particle concentration (> 100 µg/mL). Exposure to composite dust resulted in upregulation of fibronectin expression.
Significance:
Grinding of dental composite materials generates dust particles of different sizes. The particle size distribution seems to be more influenced by the suspending medium than the material itself. While cell growth of HGK seem not to be affected by the particles, an upregulation of fibronectin in the intercellular space concomitant by increasing particle concentration may indicate an increase of cell migration/mobility.
