title: The relationship between nasal airway size and nasal-oral breathing.
abstract: Most clinicians agree that impaired nasal breathing results in obligatory mouth breathing. Some believe that mouth breathing influences dentofacial growth; others disagree. The term mouth breathing is confusing because total mouth breathing rarely occurs. A combination of nasal and oral breathing is more usual. The purpose of the present study involving 116 adult subjects was to (1) assess the relationship between nasal impairment and nasal-oral breathing, (2) determine the switching range from nasal to nasal-oral breathing, and (3) quantify the term mouth breathing. The pressure-flow technique was used to estimate nasal airway size; inductive plethysmography was used to assess nasal-oral breathing in normal and impaired breathers. Analysis of the date showed a Pearson rank correlation of 0.545 (P less than 0.001) between nasal area and nasal-oral respiration. Ninety-seven percent of subjects with a nasal size less than 0.4 cm2 were mouth breathers to some extent. About 12% of subjects with an adequate airway were assumed to be habitual mouth breathers. The findings indicate that the switching range from nasal to nasal-oral breathing is very narrow (0.4-0.45 cm2). These results also confirm our contention that in adults an airway less than 0.4 cm2 is impaired.
authors.affiliation: School of Dentistry, University of North Carolina, Chapel Hill.
authors.forename: D W
authors.initials: DW
authors.lastname: Warren
authors.forename: W M
authors.initials: WM
authors.lastname: Hairfield
authors.forename: D
authors.initials: D
authors.lastname: Seaton
authors.forename: K E
authors.initials: KE
authors.lastname: Morr
authors.forename: L R
authors.initials: LR
authors.lastname: Smith
mesh_terms: D000328:Adult; D000402:Airway Obstruction / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D009058:Mouth Breathing / Q000503:physiopathology*; D009666:Nose / Q000033:anatomy & histology* / Q000502:physiology; D011312:Pressure; D012123:Pulmonary Ventilation; D012119:Respiration; D012212:Rheology