Cytotoxicity of bracket identification dyes

To investigate the potential cytotoxicity of the bracket identification dyes commonly used in orthodontic fixed appliances.

Six bracket brands representing the market in various aspects were selected. Ten sets of each bracket brand were acquired, and the identification dyes on them were scraped. They were tested for cytotoxicity at three different levels of concentration (2.5 mg/mL, 5 mg/mL, and 10 mg/mL), with the aid of a real-time cell analysis system. The results were compared within and between the groups. One-way analysis of variance and Tukey's post hoc test were used for statistical analysis.

None of the six investigated dyes displayed cytotoxicity at the 2.5 mg/mL concentration. Of the investigated brands, three at 5 mg/mL and four at 10 mg/mL displayed cytotoxicity.

Some of the identification dyes in this study did display cytotoxicity at the higher concentrations tested. Alternative methods for bracket identification should be considered.