Cytotoxicity of colored orthodontic bracket and wire

Objective: Investigating the biocompatibility in vitro of a new kind of colored orthodontic bracket and wire, qualitatively and quantitatively evaluating the cytotoxity of metal ions in human gingival cells. Methods: Two groups of stainless steel brackets and wires of 10 brackets (a full set) and 2 wires each (group A is colored; group B is original.) were immersed in artificial saliva for a month, and the chromium ion content was quantified by atomic absorb spectroscopy. The cytotoxicity of the immersed media was investigated with the MTT and flow cytometry assays. Results: Chromium concentrations of group A and group B were 1.49 fold and 3.06 fold higher respectively in the immersion media than in the controls. There is no cytotoxicity of the two group, both of them were similar in terms of cytotoxicity from MTT and the flow cytometry, Conclusion: The colored bracket and wire have good biocompatibility.