title: The effect of teeth extraction for orthodontic treatment on the upper airway: a systematic review.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of teeth extraction for orthodontic treatment on the upper airway.
  
  
  METHODS
  Relevant trials assessing the effect of orthodontic extractions on the upper airway were retrieved electronically through PubMed, Embase, Medline, Web of Knowledge, and the Cochrane Library. The processes of literature search, selection, quality assessment, and data extraction were performed by two authors independently.
  
  
  RESULTS
  Seven articles were included in this systematic review. They were categorized into three groups according to their indications for extractions, namely anteroposterior discrepancy (group 1), crowding (group 2), and unspecified indications (group 3). In group 1, enrolled patients were diagnosed with class I bimaxillary protrusion and had four first premolars extracted, with a significant decrease in upper airway dimension. In group 2, increase in the upper airway dimension was reported in patients who were diagnosed with class I crowding and four first premolars extracted. In group 3, all patients were adolescents and no significant change in the upper airway dimension was observed.
  
  
  CONCLUSIONS
  Currently, it is difficult to draw evidence-based conclusions because of the exceeding heterogeneity among included studies, and more qualified trials are required to provide reliable evidence. Extractions followed by large retraction of the anterior teeth in adult bimaxillary protrusion cases could possibly lead to narrowing of the upper airway. Mesial movement of the molars appeared to increase the posterior space for the tongue and enlarge the upper airway dimensions. Although the effect of teeth extraction on upper airway dimension seems to be related to indications for extraction, accepted scientific evidence is still insufficient owing to the limited number of included studies. The relationship between the upper airway size and the respiratory function has not been demonstrated. While there may be a decrease in the upper airway volume, there is no evidence that this would turn an airway more collapsible. None of the studies assessed in this review had actual functional assessment of breathing. Additional qualified trials are necessary to verify reliability.
authors: Department of Orthodontics, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, 14#, 3rd Section of Renmin South Road, 610041, Chengdu, People's Republic of China.
authors: Zhiai
authors: Z
authors: Hu
authors: Xing
authors: X
authors: Yin
authors: Jing
authors: J
authors: Liao
authors: Chenchen
authors: C
authors: Zhou
authors: Zhenjin
authors: Z
authors: Yang
authors: Shujuan
authors: S
authors: Zou
mesh_terms: D000293:Adolescent; D000402:Airway Obstruction / Q000175:diagnosis / Q000601:surgery; D006801:Humans; D008311:Malocclusion, Angle Class I / Q000601:surgery; D009972:Orthodontics, Interceptive; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000601:surgery*; D014081:Tooth Extraction
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