title: X-ray examination of the stomach bubble after frequent experimental swallowing of saliva: the mechanism of aerophagia.
abstract: BACKGROUND
  While the mechanism of aerophagia remains unclear, the frequency of clenching has been reported to be increased when under stress. We hypothesized that, via the swallowing reflex, chronic air swallowing was induced through a "learned habit" of the oral cavity, which was acquired through psychological factors. This study examined whether the habitual repeated swallowing in the oral cavity was a process of aerophagia.
  
  
  METHODS
  After continuous experimental saliva swallowing, changes in the stomach bubble were examined by abdominal X-rays in a standing position. The subjects included 9 males and 10 females aged 20 to 36 years that were without organic disease in the pharynx and nasal cavity. X-ray images were digitized, and the area of the stomach bubble was measured by tracing.
  
  
  RESULTS
  A close correlation was revealed in the stomach bubble area between posteroanterior and lateral views in six males (p<0.001, r = 0.910). In 3 males and 10 females, the area of the stomach bubble by posteroanterior view after 30 swallows was significantly increased compared with that before swallowing (p = 0.004).
  
  
  CONCLUSIONS
  In the present study, abdominal X-rays confirmed that frequent saliva swallowing expanded the stomach bubble.
authors: Head and Neck Psychosomatic Medicine, Department of Comprehensive Oral Health Care, Division of Comprehensive Patient Care, Graduate School, Tokyo Medical and Dental University, Japan. ogami.ompm@tmd.ac.jp
authors: Junya
authors: J
authors: Ogami
authors: Shigeru
authors: S
authors: Ono
authors: Naoko
authors: N
authors: Naka
authors: Kei
authors: K
authors: Watanuki
authors: Satoshi
authors: S
authors: Ishida