Toxicity of Metal Ions Released from a Fixed Orthodontic Appliance to Gastrointestinal Tract Cell Lines

Ksenija Durgo; Sunčana Orešić; Marijana Rinčić Mlinarić; Željka Fiket; Gordana Čanadi Jurešić

doi:10.3390/ijms24129940

Toxicity of Metal Ions Released from a Fixed Orthodontic Appliance to Gastrointestinal Tract Cell Lines

Int J Mol Sci. 2023 Jun 9;24(12):9940. doi: 10.3390/ijms24129940.

Authors

Ksenija Durgo¹, Sunčana Orešić¹, Marijana Rinčić Mlinarić², Željka Fiket³, Gordana Čanadi Jurešić⁴

Affiliations

¹ Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, Universtiy of Zagreb, Pierrotijeva 6, 10000 Zagreb, Croatia.
² Private Orthodontic Practice, Katarine Zrinske 1b, 23000 Zadar, Croatia.
³ Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia.
⁴ Department of Medical Chemistry, Biochemistry and Clinical Chemistry, Faculty of Medicine, Universtiy of Rijeka, B. Branchetta 20, 51000 Rijeka, Croatia.

Abstract

The mechanism of toxicity and cellular response to metal ions present in the environment is still a very current area of research. In this work, which is a continuation of the study of the toxicity of metal ions released by fixed orthodontic appliances, eluates of archwires, brackets, ligatures, and bands are used to test the prooxidant effect, cytotoxicity, and genotoxicity on cell lines of the gastrointestinal tract. Eluates obtained after three immersion periods (3, 7, and 14 days) and with known amounts and types of metal ions were used. Four cell lines-CAL 27 (human tongue), Hep-G2 (liver), AGS (stomach) and CaCo-2 (colon)-were treated with each type of eluate at four concentrations (0.1×, 0.5×, 1.0×, and 2.0×) for 24 h. Most eluates had toxic effects on CAL 27 cells over the entire concentration range regardless of exposure time, while CaCo-2 proved to be the most resistant. In AGS and Hep-G2 cells, all samples tested induced free radical formation, with the highest concentration (2×) causing a decrease in free radicals formed compared to the lowest concentrations. Eluates containing Cr, Mn, and Al showed a slight pro-oxidant effect on DNA (on plasmid φX-174 RF I) and slight genotoxicity (comet assay), but these effects are not so great that the human body could not "resist" them. Statistical analysis of data on chemical composition, cytotoxicity, ROS, genotoxicity, and prooxidative DNA damage shows the influence of metal ions present in some eluates on the toxicity obtained. Fe and Ni are responsible for the production of ROS, while Mn and Cr have a great influence on hydroxyl radicals, which cause single-strand breaks in supercoiled plasmid DNA in addition to the production of ROS. On the other hand, Fe, Cr, Mn, and Al are responsible for the cytotoxic effect of the studied eluates. The obtained results confirm that this type of research is useful and brings us closer to more accurate in vivo conditions.

Keywords: cytotoxicity; gastrointestinal tract cell lines; genotoxicity; metals; orthodontic appliance; prooxidant effect.

MeSH terms

Caco-2 Cells
Gastrointestinal Tract / chemistry
Humans
Ions / analysis
Metals / toxicity
Nickel* / toxicity
Orthodontic Appliances*
Orthodontic Appliances, Fixed
Reactive Oxygen Species

Substances

Reactive Oxygen Species
Nickel
Metals
Ions

Grants and funding

This research was funded by the Croatian Science Foundation within the framework of the Slovenian–Croatian bilateral project (IPS-2020-01-7418): “Determination of the occurrence, cause and harmful effects of oxidative stress caused by the use of fixed orthodontic appliances”.