The nasotracheal intubation is preferred for oral surgery; it provides an easier view of the surgical field. However, nasotracheal tubes are produced by foreign countries. Tubes are often not fitted in anatomy of Korean people because of small nostril. When the size of the tube is chosen by nostril size, the length of nasotracheal tube is not appropriate to the glottis. The aim of this study is to evaluate the appropriateness of the tube depth and to suggest the ideal length of the nasotracheal tube during the intubation of the selected tracheal tube in consideration of the size of the nasal cavity in Koreans. 146 patients (73 males and 73 females) who are scheduled for nasal intubation for general anesthesia will be enrolled. The primary outcome is the ideal length of tube that allows the distance from the vocal cords to the proximal portion of the tube cuff to be greater than 2 cm and the tip of the intubated tube to be located 5 ± 2 cm above the tracheal carina. The size of nostril, length from the nare to the carina and vocal cord are measured.

Inclusion Criteria:

1. Patients who are scheduled for nasotracheal intubation for general anesthesia

Exclusion Criteria:

1. age<20 years
2. ASA class III or more
3. pregnancy
4. emergency surgery
5. nasal airway disease
6. expected difficult intubation (difficult intubation history, Modified Mallampati score 4, mouth opening <2cm, facial anomaly)
7. cervical movement disorder (cervical disease, cervical pain)

Patients who are scheduled for nasotracheal intubation for general anesthesia