Dear editor

I read with interest the recent article entitled ‘Extra-oral appliances in orthodontic treatment’ by Almuzian M, Alharbi F, McIntyre G (Dent Update 2016; 43: 74–82).

Whilst this article provided a comprehensive review of the subject, it omitted any consideration of the airway. Recent concerns have been raised about the impact of orthodontic treatment on the airway. In particular, the reduction of overjet by upper premolar extractions and retraction of incisors.^1,2

A number of authors have found that extra-oral traction to the maxilla reduces the depth of the oropharyngeal airway.^3,4,5 This has greater impact because it is generally used in Class II cases, which already have a reduced oropharyngeal airway compared to Class I or Class III cases.^6,7,8