Authors' response

We thank Drs Vitral, Fernandes, Fraga, and Campos for their observant comments on our study.1 We agree that, mainly as a consequence of the study design, the research had some limitations. Most of the ones pointed out in the letter, including the influence of growth, the effect of treatment with fixed edgewise appliances, and the use of the variable "prescribed amount of expansion," are discussed in the article. Some of these limitations were unavoidable, since we used a retrospective design; it was not an "experiment" as suggested by the commentators.

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