In vitro cytotoxic effects of orthodontic appliances.

The objective of this study was to evaluate the effects of an orthodontic appliance and of its components (brackets, bands, and arch wires) on some cell functions. Fibroblasts were cultured either in the presence of one unwashed orthodontic appliance, or one orthodontic appliance immersed in MEM for 28 days before use (washed appliance), or in the presence of MEM in which the appliances had been immersed. At the end of in vitro maintenance, morphological studies were carried out with SEM and TEM. Cell proliferation and GAG synthesis and secretion by radio-labeled precursors were assessed. The data indicated that unwashed appliances were more cytotoxic than washed ones. Moreover, the arch wire was the most biocompatible component of the orthodontic appliance, and the bracket was the least biocompatible. A comparative study into the effects on cell proliferation of the most common metal ions released by the appliances was also carried out. At the concentration released by one orthodontic appliance immersed for 28 days, the highest reduction in DNA synthesis was observed in the presence of Cu(++).