We read the article “Effect of maxillary protraction with alternating rapid palatal expansion and constriction vs expansion alone in maxillary retrusive patients: a single-center, randomized controlled trial” in the October 2015 issue with great interest. The study compared the effects of facemask protraction combined with alternating rapid palatal expansion and constriction (Alt-RPE/C) vs rapid palatal expansion alone in maxillary retrusive patients and concluded that Alt-RPE/C with maxillary protraction positively affects the forward movement of the maxilla compared with rapid palatal expansion alone. The confounding factors such as age and sex were not mentioned in the article.
Whereas we do accept that this study was a well-designed randomized control trial providing considerable evidence for clinicians to adopt the new expansion regimen, we request the authors to consider the following.
In this study, the achievement of a positive overjet was the treatment completion criterion. The authors concluded that Alt-RPE/C with maxillary protraction might result in a greater orthopedic-orthodontic ratio in maxillary movement with similar treatment times. We wonder whether the pretreatment overjet considerations would have altered the duration of time required for different patients and whether this would have made a difference and altered the secondary outcome.
The authors correctly observed that the elastic protraction direction is 1 cause for maxillary rotation. They concluded that the palatal plane rotated more counterclockwise in the Alt-RPE/C group, and this was attributed to the expansion protocol. We humbly submit that the pretreatment occlusal plane also has a role to play in the perceived effect.
With the mandibular plane angles (MP-SN) of 33.11° and 35.14° in the RPE and Alt-RPE/C groups, respectively, we would like to know why a bonded rapid maxillary expander was not considered. The results also showed a statistically significant increase in the mandibular plane angle after treatment in both groups.
Although the anteroposterior and vertical planes of space were considered, a note on the dimensional changes brought about in the transverse plane by both regimens would have enabled readers to make an informed decision.