Overall, the study is clear and interesting. It adds clinically relevant information to the available literature. The major flaws of the article are the lack of transparency in several areas such as the details the conflict of interest and the pilot study done for calibration of the evaluators.

The aim of the study is clear and the approach taken in the clinical trial was clearly outlined in the abstract. The title is clear, informative and relevant. The references appear relevant, referenced correctly and relatively recent with respect to when the paper itself was published. I am unable to comment on whether all relevant key studies have included as I lack the expertise to do so. It is advantageous that the number of references is sizeable.

The background provided surrounding the prevalence and impact of dental fluorosis and the treatment options available are appropriate. The research question at hand is clear and justified in light of the given background. More information about the available literature on the effectiveness of carbamide peroxide and hydrogen peroxide as treatments for dental fluorosis or generally as a bleach would give the aim more justification and support. The introduction was overall brief and could be expanded upon to provide more justification for this particular study.

The process is clearly explained with sufficient detail provided. Justification for the choice of brands and thus concentrations of carbamide peroxide and hydrogen peroxide was not given. Was there a conflict of interest involved? What other relevant concentrations of the solutions could have been compared? What available brands were excluded from the study? The inclusion and exclusion criteria for participants was clear and appropriate. What was the demographic (e.g. ethnicity) of the participants like? What did the process of seeking out these participants look like? Information about the pilot study to calibrate evaluators was not provided; were there measures in place to ensure reliability of the calibration? The statistical tests done for analysis of the results were appropriate.

The data was presented clearly and appropriately. The statistical differences present and not present are clear. Qualitative data was included which enhances meaning and gives more background to the quantitative data.

Much of the discussion surrounds the known research on the potential side effects of the solutions at hand, with some mention of the limitations of the methodology. Much more should have been said about the results of the study itself. The discussion seemed to lack analysis from a range of angles. The conclusions does answer the aim of the study. Direction for further studies is given. Conflict of interest is disclosed under the acknowledgements; the study was sponsored by a government agency in Mexico. The context surrounding this relationship is not known to me but is worth highlighting.