Most orthodontic appliances are metal and contain many metal elements, such as nickel, chromium, copper, and silver, which have been confirmed to be cytotoxic at high concentrations. Thus, the biosecurity of these metals needs to be tested. Metal brackets with concentrations of less than 5% nickel have also been confirmed to be cytotoxic. These brackets, such as metal buccal tube with copper and zinc, affect cell morphology and proliferation. The factors affecting the release of metal ions are as follows: metal elements, surface structure, protein, immersing category, immersing time, and immersing potential of hydrogen. Currently, the complementary methods of Comet and micronuclear tests are mainly used to test genotoxicity. This article aimed to discuss the cytotoxicity and genotoxicity of metal orthodontic appliances in terms of ion release, as well as study cytotoxicity and genotoxicity. This article will offer reference for others.
