Occurrence and effects of oxidative stress induced by metal materials from fixed orthodontic appliances

Kovač, Vito (author), Poljšak, Borut (mentor), Jamnik, Polona (comentor)

Misaligned 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.

• Language: English
• Keywords: Oxidative stress, ROS, metal ions, nanoparticle, orthodontic appliance, Saccharomyces cerevisiae, HGF
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: BF - Biotechnical Faculty
• Year: 2022
• PID: 20.500.12556/RUL-142311
• COBISS.SI-ID: 128082947
• Publication date in RUL: 29.10.2022

Secondary language

• Language: Slovenian
• Title: Nastanek in učinki oksidativnega stresa, povzročenega s kovinskimi materiali nesnemnih ortodontskih aparatov

Abstract

Malokluzija se pogosto odpravi s nesnemnimi ortodontskimi aparati. Dolgotrajna izpostavljenost ortodontskega aparata v ustnem okolju vodi do korozije in obrabe materiala, iz katerega se lahko sprostijo kovinski ioni in nanodelci, ki katalizirajo reakcije nastanka reaktivnih kisikovih zvrst in posledično povzročijo oksidativni stres. Namen disertacije je bil raziskati sistemske spremembe parametrov oksidativnega stresa med ortodontskim zdravljenjem, sestavo izbranih ortodontskih zlitin, sproščanje kovinskih ionov in oksidativne posledice, ki jih lahko imajo kovinski ioni na modelni organizem Saccharomyces cerevisiae (S. cerevisiae). Namen disertacije je bil tudi raziskati učinke nanodelcev na celično linijo fibroblastov človeške dlesni (HGF). Povečanje ravni sistemskega oksidativnega stresa je bilo mogoče opaziti v kapilarni krvi ortodontskih pacientov šele po 24 urah, nato pa se parametri oksidativnega stresa normalizirajo. Sproščanje kovinskih ionov iz ortodontskih aparatov v umetno slino je konstantno, vendar so koncentracije sproščenih kovin še vedno pod maksimalno dovoljeno dnevno dozo. Le visoke koncentracije kovinskih ionov so sposobne ustvariti velike količine reaktivnih kisikovih zvrst v kvasovki S. cerevisiae, katerih antioksidativni sistem ni zmožen uravnati, in zato prihaja do oksidativnega stresa in oksidativnih poškodb molekul. Toksičnost nanodelcev in sposobnost ustvarjanja reaktivnih kisikovih zvrsti v celični liniji HGF je odvisna od vrste, koncentracije in lastnosti nanodelcev. Dokazali smo, da se iz nesnemnih zobnih aparatov sproščajo kovinski ioni, čigar koncentracije so prenizke, da bi lahko povečale nivo ROS in inducirale oksidativni stres v kvasovki S. cerevisiae, čeprav so bile opažene nekatere spremembe v aktivnosti antioksidativnih encimov. Izmed izbranih nanodelcev so se nanodelci WS2 izkazali kot najmanj toksični v celični liniji HGF.

• Keywords: Oksidativni stres, ROS, kovinski ioni, nanodelci, ortodonski aparati, Saccharomyces cerevisiae, HGF