The goal of this prospective randomized controlled study is to investigate the effect of head tilting on tracheal tube passing during nasotracheal intubation.

The question which the investigators are trying to answer is: If patient's neck is extented on inserting tracheal tube via nostril, will the E-tube be more easily to pass through nasopharynx to oropharynx without trapping?

For nasotracheal intubation, clinicians do sometimes experience tube trapping at naso/oro-pharyngeal tissue. Application of force to overcome resistance can cause tissue injury leading to bleeding, which can disturb tracheal intubation.

The hypothesis of this study is that the method of 'head tilting' can help easy passing of tracheal tube at naso/oro-pharyngeal pathway without trapping in nasotracheal intubation. The purpose of the present study is to investigate the effect of 'head tilting' on the incidence of trapping of tracheal tube at naso/oro-pharynx when tracheal tube is being advanced into oropharynx via nostril during nasotracheal intubation.

Inclusion Criteria:

• The patients who need to nasotracheal intubation for surgery.

Exclusion Criteria:

• Who doesn't agree to enroll
• Who has a problem to head tilting position such as C-spine injury.