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Effects of Denture Removal on Expiratory Upper Airway Patency during Mask Ventilation in Complete Denture Wearers under General Anesthesia

Background: Some anesthetized patients present with expiratory airway obstruction (EAO) during mask ventilation (MV). EAO may occur more frequently among edentulous patients for whom a firmer grip of the mask and the mandible is needed to avoid gas leakage. We compared EAO grades before and after denture removal and identified predictors of EAO during MV in edentulous patients. Methods: One hundred and eight denture-wearing edentulous patients were anesthetized, their mouths were wrapped with film, their nasal masks and mandibles were held with two hands, and their lungs were ventilated in a pressure-controlled mode. Their dentures were subsequently removed, mouths were re-wrapped, and nasal MV was reapplied. EAO was graded based on capnography waveforms as follows: Grade I, normal waveform (no obstruction); II, loss of the alveolar plateau of the waveform (partial obstruction); and III, no waveform (total obstruction). EAO grades were compared before and after denture removal. Predictive demographic variables for occurrence of total EAO were identified using a multivariate analysis. Results: The proportions of Grades I, II, and III were 43.5%, 26.9%, and 29.6% when dentures were worn and 35.2%, 15.7%, and 49.1%, respectively, when dentures were removed. A significant difference was observed in EAO grades before and after denture removal (P = 0.000034). Age ≥ 75 years (adjusted odds ratio 3.41; 95% confidence interval 1.31 - 8.87; P = 0.012) and body mass index ≥ 25 kg/m2 (adjusted odds ratio 2.61; 95% confidence interval 1.07 - 6.40; P = 0.036) were independently associated with an increased incidence of total EAO in patients with their dentures removed. Conclusion: Denture removal impaired expiratory upper airway patency in edentulous patients, particularly in older or obese patients, during MV.