title: The effect of mouth breathing on chewing efficiency.
abstract: OBJECTIVE
  To examine the effect of mouth breathing on chewing efficiency by evaluating masticatory variables.
  
  
  METHODS
  Ten adult nasal breathers with normal occlusion and no temporomandibular dysfunction were selected. Subjects were instructed to bite the chewing gum on the habitual side. While breathing through the mouth and nose, the glucide elution from the chewing gum, number of chewing strokes, duration of chewing, and electromyography (EMG) activity of the masseter muscle were evaluated as variables of masticatory efficiency.
  
  
  RESULTS
  The durations required for the chewing of 30, 60, 90, 120, 180, and 250 strokes were significantly (P < .05) longer while breathing through the mouth. There was no significant difference in the glucide elution rate (%) for each chewing stroke between nose and mouth breathings. The glucide elution rates for 1- and 3-minute chewing were significantly (P < .05) lower while breathing through the mouth. However, there was no significant difference in the glucide elution rate for 5-minute chewing between nose and mouth breathings. While chewing for 1, 3, and 5 minutes, the chewing stroke and EMG activity of the masseter muscle were significantly (P < .05) lower during mouth breathing.
  
  
  CONCLUSIONS
  It takes a longer amount of time to complete chewing to obtain higher masticatory efficiency when breathing through the mouth. Therefore, mouth breathing will decrease the masticatory efficiency if the duration of chewing is restricted in everyday life.
authors.affiliation: a  Postgraduate Student, Division of Orofacial Functions and Orthodontics, Department of Health Improvement, School of Dentistry, Faculty of Kyushu Dental University, Kitakyushu, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Nagaiwa
authors.affiliation: b  Assistant Professor Division of Orofacial Functions and Orthodontics, Department of Health Improvement, School of Dentistry, Faculty of Kyushu Dental University, Kitakyushu, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Gunjigake
authors.affiliation: c  Emeritus Professor, Kyushu Dental University, Kitakyushu, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yamaguchi
mesh_terms: D002638:Chewing Gum; D004576:Electromyography; D006801:Humans; D008406:Masseter Muscle / Q000502:physiology*; D008409:Mastication / Q000502:physiology*; D009058:Mouth Breathing
chemical_list: D002638:Chewing Gum
keywords: Chewing duration; Chewing gum; Chewing stroke; Glucide elution rate; Mouth breathing