The release of metal ions from orthodontic appliances: Animal tests

Objective:To investigate the release of metal ions from an orthodontic appliance in tests on animals (pigs).Materials and Methods:An animal test was conducted on 24 pigs divided equally into an experimental and a control group. In total, 12 sets of experimental orthodontic plates were surgically inserted into pig snouts in the experimental group for 6 months. Noninvasive matrices (hair [0, 3, and 6 months]) and invasive matrices (kidneys, liver, lungs, aorta, and oral mucosa) were collected for multi-elemental analysis (inductively coupled plasma optical emission spectrometry) from the experimental and control groups.Results:The greatest differences in the content of toxic metals were found in the aorta (Ni level was 4.8 times higher in experimental than in the control group), in the cheek (Ni 3.5 times higher), and in the hair sampled after 3 months (Cr 3.4 times higher).Conclusions:The obtained data indicate that the products of corrosion have passed into selected tissues of pigs; however, the doses of toxic metal ions released from the appliance did not reach toxic levels.