Tooth loss and obstructive sleep apnoea

Complete tooth loss (edentulism) produces anatomical changes that may impair upper airway size and function. The aim of this study was to evaluate whether edentulism favours the occurrence of obstructive sleep apnoea (OSA). Polysomnography was performed in 48 edentulous subjects on two consecutive nights, one slept with and the other without dentures. Upper airway size was assessed by cephalometry and by recording forced mid-inspiratory airflow rate (FIF50). Exhaled nitric oxide (eNO) and oral NO (oNO), were measured as markers of airway and oropharyngeal inflammation. The apnoea/hypopnoea index (AHI) without dentures was significantly higher than with dentures (17.4 +/- 3.6 versus 11.0 +/- 2.3. p = 0.002), and was inversely related to FIF50 (p = 0.017) and directly related to eNO (p = 0.042). Sleeping with dentures, 23 subjects (48%) had an AHI over 5, consistent with OSA, but sleeping without dentures the number of subjects with abnormal AHI rose to 34 (71%). At cephalometry, removing dentures produced a significant decrease in retropharyngeal space (from 1.522 +/- 0.33 cm to 1.27 +/- 0.42 cm, p = 0.006). Both morning eNO and oNO were higher after the night slept without dentures (eNO 46.1 +/- 8.2 ppb versus 33.7 +/- 6.3 ppb, p = 0.035, oNO 84.6 +/- 13.7 ppb versus 59.2 +/- 17.4 ppb, p = 0.001). These findings suggest that complete tooth loss favours upper airway obstruction during sleep. This untoward effect seems to be due to decrease in retropharyngeal space and is associated with increased oral and exhaled NO concentration.