No treatment is effective if patients are not compliant. This is an inherent problem when comparing the effects of nonsurgical treatments to those of surgical treatments. Patients can stop taking drugs or, in this case, can stop using a dental appliance. Once operated on, however, they cannot withdraw from treatment. Even in the best-designed, best-managed, short-term clinical trials, there will be patients who withdraw.2 In a clinical trial in which treatment extends over an unusually long period (4 years in our study), the risk of withdrawals from treatment, as expected, increases quite a lot, even though the results of a clinical trial often differ from the those of clinical practice because of the careful monitoring of patients in the trial. Therefore, it might be more appropriate to use the term efficacy instead of effectiveness in clinical trials. The careful description of the number of withdrawals and the exact reasons for them are important issues in interpreting the results in a clinical trial. Such an analysis was performed in our study. That compliance is an important response variable is well-documented in our article and is also included in the conclusion section of the article.