Nano-TiO2 penetration of oral mucosa: in vitro analysis using 3D organotypic human buccal mucosa models
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Published on: December 23, 2022
Victoria Konstantinova1,2,3, Mohamed Ibrahim1,3, Stein A Lie1
1Department of Clinical Dentistry, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway.
Background:
Oral cavity is a doorway for a variety of products containing titanium dioxide (TiO2 ) nanoparticles (NPs) (nano-TiO2 ) such as food additives, oral healthcare products and dental materials. Their potential to penetrate and affect normal human oral mucosa is not yet determined.
Objectives:
To evaluate the ability of nano-TiO2 to penetrate the in vitro reconstructed normal human buccal mucosa (RNHBM).
Methods:
RNHBM was generated from primary normal human oral keratinocytes and fibroblasts isolated from buccal oral mucosa of healthy patients (n = 6). The reconstructed tissues were exposed after 10 days to clinically relevant concentrations of spherical or spindle rutile nano-TiO2 in suspension for short (20 min) and longer time (24 h). Ultrahigh-resolution imaging (URI) microscopy (CytoViva™ , Auburn, AL, USA) was used to assess the depth of penetration into reconstructed tissues.
Results:
Ultrahigh-resolution imaging microscopy demonstrated the presence of nano-TiO2 mostly in the epithelium of RNHBM at both 20 min and 24-h exposure, and this was shape and doze dependent at 24 h of exposure. The depth of penetration diminished in time at higher concentrations. The exposed epithelium showed increased desquamation but preserved thickness.
Conclusion:
Nano-TiO2 is able to penetrate RNHBM and to activate its barrier function in a doze- and time-dependent manner.
