I read an interesting case report in the February issue (Wang H, Feng J, Lu P, Shen G. Correction of a skeletal Class II malocclusion with severe crowding by a specially designed rapid maxillary expander. Am J Orthod Dentofacial Orthop 2015;147:242-51). I have some questions about parts of this case presentation.

First, the title of the article is focused on a newly designed rapid maxillary expander. However, when I read the article, I saw that the authors did not perform a rapid maxillary expansion procedure. Hence, they did not mention the opening of the midpalatal suture in the text. They reported that the activation protocol for the 3 expansion screws was 1 turn every other day. This means 1 turn in 6 days for each screw. I wonder whether this screw-turning protocol for the expansion (1 turn in 6 days) is sufficient for the sutural opening and the orthopedic effect. Is this appliance a maxillary expander or a rapid maxillary expander?

Second, the authors mentioned that the orthopedic forces generated by this appliance created spaces to provide relief of crowding in the labial segment and moved molars distally to achieve a Class I molar relationship. In the first 6 months of the treatment, the anterior teeth were protruded and then leveled with the help of fixed appliances. In the second phase of treatment, they used a microimplant to reinforce the anchorage during the retraction of the anterior teeth. They protruded the anterior teeth in the first 6 months and then retracted them in the second phase. When I focused on the posttreatment panoramic radiographs, I observed a serious root shortening of anterior teeth, especially at the lateral incisors, which may be considered an apical root resorption. What are the possible reasons for this apical root resorption?

Finally, the effects of this newly designed expander are mostly dental and dentoalveolar. The authors mentioned that they moved the maxillary molars distally and corrected the molar relationship from Angle Class II to Class I. On the other hand, they mentioned that the patient’s skeletal base changed from Class II to Class I. The authors should explain how they were able to manage the correction of a skeletal Class II malocclusion into a Class I.