D

History of snoring, presence of a beard, and age > 55 years were all identified as independent predictors of difficult mask ventilation in large prospective studies, whereas lack—not presence—of teeth increases difficulty; therefore a patient with a full set of teeth is least associated with difficult mask ventilation [Langeron et al., 2000, PMID 10781266; El-Orbany & Woehlck, 2009, PMID 19923516].