Letter to the Editor

To: Editor, The Angle Orthodontist

Re: Effects of rapid maxillary expansion on upper airway volume: A three-dimensional cone-beam computed tomography study. Yousef Abdalla, Louise Brown, Liselotte Sonnesen. Angle Orthod. 2019; 89: 917-923.

This paper investigated the effects of RME on upper airway volume utilizing CBCT. However, there are still a few questions remaining:

1. Patients with previous adenotonsillectomy were excluded from the treatment group. However, adenoid hypertrophy was not discussed. Was this part of the exclusion criteria? Based on previous research, adenoid hypertrophy would obstruct the upper airway¹. If adenoid hypertrophy was not excluded, the results on upper airway volume were possibly biased.

2. There were no significant differences in the skeletal measurements between the RME and matched control groups pre-treatment. This could imply that patients in the RME group did not have skeletal maxillary transverse deficiency. Additionally, mandibular width before treatment was within the normal range. Therefore, the posterior crossbite in the treated group may not have been skeletal but dental in origin. Accordingly, the conditions of the patients assigned to the treated group may not have met the indications for requiring RME.