In vivo evaluation of the genotoxic effects of Hyrax auxiliary orthodontic appliances containing silver-soldered joints

Auxiliary appliances consisting of silver-soldered joints may be present in the patient's oral cavity for a long time. The aim of this study was to investigate, in vivo, the potential genotoxic effects of Hyrax-type maxillary expanders containing silver-soldered joints on the cells of the buccal mucosa. Buccal cells were collected from 20 patients and processed to perform the buccal comet assay (BCA) and the buccal micronucleus cytome (BMCyt) assay, to investigate DNA and chromosomal damage, respectively. For the BCA, patients were evaluated before and 14 days after the appliances were installed. For the BMCyt assay, the patients were evaluated longitudinally; before the insertion of the appliance and after one, six, and twelve months. The BCA showed significant increases in damage frequency and damage index in exfoliated buccal cells, following insertion of the appliance. For the BMCyt assay, the endpoints related to cell proliferation, cell death, and chromosomal damage (micronuclei and nuclear buds) resulted in no significant differences over the 12-month study period. In conclusion, the use of orthodontic appliances containing silver-soldered joints can significantly increase DNA damage as measured by the BCA.