Assessment of Facial Measurements, the Length of Mouth Corner-mandible Angle and Incisors-mandible Angle, for Determining the Proper Sizes of Oropharyngeal Airway

The purpose of this study is to assess the facial measurements for determining the proper sizes of oropharyngeal airway. Investigators hypothesized that the length between incisors and mandible angle is more appropriate to estimate the size of oropharyngeal airway compared with the length between mouth corner and mandible angle.

Inclusion Criteria:

• adult patients undergoing surgery that requires general anesthesia

Exclusion Criteria:

• anticipated difficult intubation
• patients without teeth or with loose teeth
• cervical spine disease
• upper airway disease
• body mass index over 35 kg/m2
• pregnancy