We read the article by Dr Tomonori Iwasaki et al (Iwasaki T, Sato H, Suga H, Takemoto Y, Inada E, Saitoh I, et al. Relationships among nasal resistance, adenoids, tonsils, and tongue posture and maxillofacial form in Class II and Class III children. Am J Orthod Dentofacial Orthop 2017;151:929-40) about differences of upper airway factors between Class II and Class III children.

We were interested in the study since the influence of the upper airway on developing children has begun to draw more attention. Many studies also have shown that the impact of respiratory obstruction on facial growth could be prominent in growing patients. As shown in the Material and methods section, subjects between 7 and 12 years of age were chosen. Since the size of adenoids might change as children in the mixed dentition grow up, was there any other consideration for choosing them as the subjects? Could children in the early permanent dentition be subjects?

Constriction of the maxillary dentition was found in the study to be associated with nasal obstruction, inferior tongue posture, and enlarged tonsils. Since young children might not be cooperative, was there an optimal time to correct tongue posture and nasal obstruction to prevent the maxillary dentition constriction?

Upper airway changes between preorthodontic and postorthodontic treatment in the subjects also attracted our attention. Might there be any correlation between the upper airway and the fine retention? We appreciated the authors’ efforts to share the experience with the readers.