Several studies have reported that the most effective breathing pattern is nasal breathing during wakefulness and open-mouth breathing induce upper airway narrowing by the morphological changing of the upper airway. The aim of the present study was to conduct an objective investigation of upper airway morphological changes corresponding with changes in breathing patterns using sleep endoscopy and three-dimensional imagery of the upper airway by a volume rendering technique with MDCT images. Result: The endoscopic findings of tongue retreating during wakeful mouth breathing were obtained with both obstructive sleep apnea syndrome (OSAS) patients and a normal control. It was confirmed that the narrowing of the upper airway with OSAS patients worsened. Three-dimensional images of the upper airway by a volume rendering technique with MDCT images was also successful in obtaining findings in changes of breathing patterns using endoscopy. It was very helpful to be able to observe from any angle. Conclusion: These methods have potential in establishing an objective evaluation method, as well as being very useful in providing a visually descriptive explanation to patients.
