Impact of Open-Mouth Breathing on Upper Airway Anatomy in Patients with Sleep-Disordered Breathing

ABSTRACT

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate the impact of open-mouth breathing on the upper airway anatomy of patients with sleep-disordered breathing (SDB) based on polysomnography. MATERIALS AND METHODS: A total of 114 subjects (101 males and 13 females) with a mean age of 42.7 years and a mean body mass index (kg/m2) of 26.2 were enrolled in this study. All subjects were divided into four groups (simple snoring, mild obstructive sleep apnea syndrome[OSAS], moderate OSAS and severeOSAS) according to the apnea-hypopnea index. Lateral cephalometric radiograms (retropalatal, retroglossal, and hypopharyngeal distance, and pharyngeal length) were taken with the mouth closed and open. RESULTS: The lateral cephalometric variables were compared between the mouth closed and open positions, and it was found that the retropalatal and retroglossal distances and pharyngeal length were significantly changed in all groups. However, the hypopharyngeal distance did not change significantly in any of the groups. CONCLUSION: Open-mouth breathing significantly reduces the retropalatal and retroglossal distance and lengthens the pharynx in patients with SDB. Since these anatomical changes may worsen SDB or decrease positive airway pressure treatment compliance, ENT doctors should attempt to convert SDB patients from open-mouth breathing to nasal breathing.