In this study, the subjects are divided into two groups (group I: intervention group = the nasotracheal tube inserted with the bevel of the nasal tube facing the direction of the patient's head, and Group II: conventional group = the bevel of the tube toward the left side of the subject). After the endotracheal tube is introduced, a flexible endoscope is used to evaluate whether the tube is located below the inferior turbinate, i.e. in the lower pathway.

Primary outcome

• incidence of tracheal tube passing through the lower pathway (beneath the inferior turbinate and immediately above the nasal floor of the nostril) Secondary outcome
• intubation time
• incidence of epistaxis
• severity of bleeding
• Resistance during Insertion of the tracheal tube

Inclusion Criteria:

• a patient who will take operation which needs nasotracheal intubation under general anesthesia

Exclusion Criteria:

• a patient who didn't agree to participate in this study
• a patient who has a deformity of the nose
• a patient who has a history of severe epistaxis
• a patient who has coagulation problem
• a patient who has a history of the fracture or surgery of the skull base