To: Editor, The Angle Orthodontist

Re: Short-term effects produced by rapid maxillary expansion and facemask therapy inClass III patients with different vertical skeletal relationships. The Angle Orthodontist. 2015;85:927-933.

Thank you for this interesting article. This was a retrospective study so we realize that the treatment methods used were not necessarily under your control.

When reading the paper, we noted that some of the starting average cephalometric values were not consistent with a diagnosis of Class III skeletal pattern: ANB was >0, A to NPerp and Pg to NPerp values were within normal limits. Also, the groups showed differences in SNB, ANB, Pg-NPerp before treatment with the hypodivergent group displaying more characteristics of mandibular protrusion. Perhaps, as a result of being less Class III skeletally to begin with, therefore, the result was a greater ANB angle of 4.6 on average in the hyperdivergent group after facemask treatment. Usually, facemask therapy is directed at patients with a retrusive maxilla so do you think this was appropriate treatment for all of the patients or could some of the patients have been treated in a different way or to a different extent?

All of the patients in the vertically different groups were treated with elastics angled at 30 degrees to the occlusal plane. Some studies reported that different angulations can cause differences in rotation of the maxilla during protraction. In your groups, there were no differences noted between them for the response to this treatment. However, since they did begin with different vertical relationships, do you think that it might have been beneficial to treat the groups differently? Do you think that the response could have been better if the treatment was individualized based on the characteristics displayed by each patient before treatment? For example, would you consider using the elastics at different angles for different skeletal patterns to get different responses?

Thank you again for stimulating this interesting discussion.