To: Editor, The Angle Orthodontist
Re: In vitro biocompatibility of nickel-titanium esthetic orthodontic archwires by Rongo Roberto, Rosa Valletta, Rosaria Bucci, et al. The Angle Orthodontist ; 2016;86:789–795.
I would like to congratulate the authors on the theme of their study because it is current and important to take into account the health concerns of patients. I have some questions to clarify the methodology used in the study.
According to the parameters of ISO10993 which regulates in vitro cytotoxicity tests, negative and positive controls shall be included in each assay because they are important for the control of the means in relation to the maximum and minimum response. It does not appear that these two control groups were part of the methodology so how do you think this might affect interpretation of the results?
Additionally, the paper does not specify the length of the wires used. This is important because wire length and thickness must be evaluated in the calculation of the area of contact of the samples with cells in the cytotoxicity assay.
Thank you for publishing this interesting paper.