Experimental: fiberoptic bronchoscope fiberoptic bronchoscope is used to facilitate for nasotracheal intubation.

Experimental: video-stylet video-stylet is used to facilitate for nasotracheal intubation.

Nasotracheal intubation is assisted by a video-stylet may be performed in patients undergoing Limited Mouth Opening following induction of anesthesia (fentanyl 2 micro-gram/kg, thiamylal 5 mg/kg) and is facilitated by cis-atracurium 0.2 mg/kg administration. propofol 1 mg/kg intravenously to blunt hemodynamic responses while intubation.

a modified intubation difficulty scale to evaluate the difficulty of fiber-scope guided or trachway assisted nasotracheal intubation

time of Intubating the nasotracheal tube (NT) from selected nostril to trachea is continuously calculated but separately into two parts. part one: from leaving off mask ventilation (mask removal from face), to the NT tip on the nasopharynx. part two: advancing NT from nasopharynx, through vocal cord into trachea, to present of 3 end tidal carbon dioxide waveforms.

Events of intubating related nasal bleeding are recorded on selected nostril and oral cavity at 3 minutes post-intubation and post-operatively. Incidences of sore throat and hoarseness are evaluated before patients out of recovery room and the following morning