Protrusion of the mandible (prognathism): Ask the patient to put their lower teeth in front of their upper teeth. There are three classes of prognathism:

Class A	Able to protrude the lower incisors anterior to the upper incisors
Class B	Lower incisors can just reach the upper incisors
Class C	Lower incisors cannot even protrude to the upper incisors

Table 1 Classes of Prognathism

Classes B and C are associated with increased risk of difficult laryngoscopy.