We read the article entitled “Change in the vertical dimension of Class II Division 1 patients after use of cervical or high-pull headgear” by Zervas et al in the November 2016 issue with great interest. The authors are appreciated for their sincere effort. Having said that, as avid readers of your Journal , we want to raise a few questions that might be beneficial to other readers.

The authors said that they chose subjects retrospectively with the groups matched for age (mean, 9 ± 2.5 years), treatment time (mean, 14 months), malocclusion, and similar skeletal features. However, since sex is also an important demographic factor, we feel that a mention of this variable would have contributed more to the methodologic aspects.

Second, the authors mentioned that both study groups were matched with an untreated growth model. Was a significant effort put into matching the untreated control sample to the treatment sample (cervical and high-pull headgears) as closely as possible with respect to sex distribution, age at T1, duration of observation, and skeletal maturity at both times?

Furthermore, the techniques of application of the headgear were not elucidated. The authors mentioned the force and duration of the headgear wear and the angulation of the outer bows for both headgears but failed to note whether the inner bow was fixed to the activator appliance or to the banded maxillary molars directly. Also, it would have been more appropriate to state whether the treatment plan included isolated activator headgear or whether the headgear was combined with a fixed appliance. Since the results of this study are quite promising, we would appreciate it if the authors would share their views on these queries.