Occurrence and effects of oxidative stress induced by metal materials from fixed orthodontic appliancesKovač, Vito (Avtor) Poljšak, Borut (Mentor) Jamnik, Polona (Komentor) Oxidative stressROSmetal ionsnanoparticleorthodontic applianceSaccharomyces cerevisiaeHGFMisaligned teeth are often corrected with fixed orthodontic appliances. Prolonged stay of the orthodontic appliance in the oral cavity leads to corrosion and wear of the material, from which metal ions and nanoparticles can be released that catalyze reactive oxygen species-generating reactions, which in turn lead to oxidative stress. The objective of this work was to investigate the level of selected systemic oxidative stress parameters during orthodontic treatment, the composition of selected orthodontic alloys, the release of metal ions, and the oxidative consequences that the metal ions may have on the model organism Saccharomyces cerevisiae (S. cerevisiae). The work also aimed to investigate the effects of nanoparticles on the human gingival cell line (HGF). An increase in systemic oxidative stress levels was detected in the capillary blood of orthodontic patients only after 24 hours, after which oxidative stress parameters normalized. The release of metal ions from orthodontic appliances into artificial saliva is constant, but the metal concentrations released are still below the maximum tolerated daily dose. Only high metal ion concentrations were able to generate large amounts of reactive oxygen species in the yeast S. cerevisiae, which the antioxidant system was unable to regulate adequately, resulting in oxidative stress and its damage to biological molecules. The toxicity of nanoparticles and the ability to generate reactive oxygen species in HGF mainly depend on the type, concentration and properties of nanoparticles. We have shown that metal ions from orthodontic appliances are released at such low concentrations that they cannot induce oxidative stress in the yeast S. cerevisiae, although some change in the antioxidant activity of the enzyme was observed. Of the selected nanoparticles, the WS2 nanoparticle was the least toxic to HGF.20222022-10-29 07:15:19Doktorsko delo/naloga142311sl