References

Singh D Impact on airway. Br Dent J. 2015; 218

Trenouth MJ Impact on airway. Br Dent J. 2015; 219

Pirila-Parkkinen K, Pirttiniemi P, Nieminen P, Lopponen H, Tolonen U, Uotila R, Huggare J Cervical headgear therapy as a factor in obstructive sleep apnea syndrome. Pediatr Dent. 1999; 21:39-45

Hiyama S, Ono T, Ishiwata Y, Kuroda T Changes in mandibular position and upper airway dimensions by wearing cervical headgear during sleep. Am J Orthod Dentofacial Orthop. 2001; 120:160-168

Godt A, Koos B, Hagen H, Goz G Changes in upper airway width associated with Class II treatment (headgear vs activator) and different growth patterns. Angle Orthod. 2011; 81:440-446

Claudino LV, Mattos CT, Ruellas ACO, SantAnna EE Pharyngeal airway characterization in adolescents related to facial skeletal pattern: a preliminary study. Am J Orthod Dentofacial Orthop. 2013; 143:799-809

Hakan E, Palomo JM An airway study of different maxillary and mandibular sagittal positions. Eur J Orthod. 2013; 35:262-270

Abdelkarim A A cone beam CT evaluation of oropharyngeal airway space and its relationship to mandibular position and dentocraniofacial morphology. J World Fed Orthod. 2012; 1:e55-59

Pae EK, Lowe AA, Fleetham JA A role of pharyngeal length in obstructive sleep apnoea patients. Am J Orthod Dentofacial Orthop. 1997; 111:12-17

Battagel JM, Johal A, Kotecha B A cephalometric comparison of subjects with snoring and obstructive sleep apnoea. Eur J Orthod. 2000; 22:353-365

Pracharktam N, Nelson S, Hans MG, Broadbent BH, Redline S, Rosenberg C, Strohl KP Cephalometric assessment in obstructive sleep apnea. Am J Orthod Dentofacial Orthop. 1996; 109:410-419

Letters to the Editor

Dear editor

M J Trenouth

From Volume 43, Issue 2, March 2016 | Page 193

Authors

M J Trenouth

Consultant Orthodontist (Retired)

Articles by M J Trenouth

Article

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

There is a well established relationship between reduced oropharyngeal airway and obstructive sleep apnoea.^9,10,11 Hence, the indiscriminate use of extra-oral traction could increase a patient's susceptibility to sleep disordered breathing and obstructive sleep apnoea and, for this reason, would be contra-indicated.