Dear editor

I should like to thank the authors for their reply to my letter (Dent Update 2016; 43: 193) regarding their article ‘Extra-oral appliances in orthodontic treatment’ Almuzian M, Alharbi F, McIntyre G (Dent Update 2016; 43: 74–82).

They cite the publication ‘Upper airway dimension in Class II malocclusion: effects of headgear treatment’ Kirjavainen M, Kirjavainen T Angle Orthod 2007; 77: 1046–1053. They correctly quote these authors findings that ‘The retropalatal area was widened by treatment, whereas the rest of the oropharynx and hypopharynx remained narrower than in controls’. This by itself is misleading and requires additional comment. To quote from these authors again ‘The important feature of the headgear used was a 10 mm expanded inner bow’. The increase in retropalatal airway space was more likely to be due to the upper arch expansion and the observed increase in lateronasal width rather than the distalizing effect of the headgear on the maxilla. The authors recognize this by the fact that they quote six references on the effects of rapid maxillary expansion on the nasal airway.^1,2,3,4,5