Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 6 2013 12 15 494 500 Farzin Heravi Dental Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran. Mohammad Reza Abbaszadegan Division of Human Genetics, Immunology Research Center, Avicenna Research Institute, Mashhad University of Medical Sciences, Mashhad, Iran. Mohsen Merati Dental Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran. Nadia Hasanzadeh Dental Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran. Ezzat Dadkhah Division of Human Genetics, Immunology Research Center, Avicenna Research Institute, Mashhad University of Medical Sciences, Mashhad, Iran. Farzaneh Ahrari Dental Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran. 2015 10 16 The release of toxic metal ions from orthodontic alloys has induced concerns regarding the biocompatibility of fixed appliances. This study investigated the genotoxic effect of metal appliances in a sample of patients undergoing fixed orthodontic treatment.The study included twenty-five healthy individuals requiring orthodontic therapy in both jaws. The patients were treated by stainless steel orthodontic brackets and nickel-titanium or stainless steel arch wires. The oral mucosa cells were gathered just before the appliance placement and 9 months later. The cells were centrifuged, fixed and dropped onto slides. After staining, the micronucleus (MN) assay was used to determine genome alteration. The data were analyzed by paired sample t-test.The mean micronuclei frequency in the buccal mucosa was 10.6 ± 5.7 per 1000 cells before the appliance placement and 9.2 ± 6.37 per 1000 cells 9 months later. No significant difference was found in the MN count before and 9 months after therapy (p=0.336).Under the conditions used in this study, application of fixed orthodontic appliances did not expose healthy individuals to increased risk of DNA damage in oral mucosa cells. https://fid.tums.ac.ir/index.php/fid/article/view/595 https://fid.tums.ac.ir/index.php/fid/article/download/595/570