Genotoxic and cytotoxic effects of Haas appliance in exfoliated buccal mucosa cells during orthodontic treatment

Objectives: To evaluate the genotoxic and cytotoxic effects of Haas appliances through micronuclei test and cytogenetic damage analysis in buccal mucosa epithelial cells of patients undergoing orthodontic treatment. Materials and Methods: Twenty-eight patients, 6-12 years of age and of both genders, who required a Haas appliance for the correction of a posterior crossbite were included. Epithelial cells from the mucosa were collected by gently scraping the inside of both the right and left cheeks. The cells were collected before the insertion of the appliance (TO), 1 month after the device was installed (T1), and again 3 months after the appliance was immobilized (T2). The cells were processed to obtain slides. Feulgen/Fast Green was used as the staining method, and the number of normal, karyolytic, pyknotic, nuclear buds, bi/trinucleated, and micronucleus cells were counted under light microscopy. Cellular abnormalities were evaluated with parametric and nonparametric tests for comparison of the means by analysis of variance testing, Tukey posttest, or the Kruskal-Wallis test and then by Dunn's posttest. The significance level was 5%. Results: There were no statistically significant changes in the micronuclei in the evaluated periods (P > .05). Nuclear buds increased at T1 (P < .05), returning to baseline levels at T2. Other abnormalities (cariolytic, pyknotic, and bi/trinucleated cells) showed a significant increase at T1 and T2 (P < .0001). Conclusions: The Haas appliance did not cause an increase in micronuclei in cells of the buccal mucosa. However, statistically significant increases in cariolytic, pyknotic, and bi/trinucleated cells were observed during treatment, suggesting possible DNA damage.