To the Editor:—

The left molar approach of laryngoscopy  is an unconventional technique in which the blade is inserted from the left corner of the mouth. The approach has been shown to provide a better view of the glottis than the conventional midline approach in cases of difficult intubation. 1We appreciate this approach for another reason, that is, to spare the incisor teeth, and would like to present our case.

A 58-yr-old woman was scheduled to undergo upper lobectomy of the right lung. The preoperative visit by an anesthesiologist revealed that her upper incisors (numbers 7–9) were mobile, even with a light touch, and her other upper teeth, with the exception of number 4, were dentures. The patient was informed that her incisors could be damaged during laryngoscopy and tracheal intubation, and verbal consent was obtained for possible damage, but she also requested that we make our best effort to spare her incisor teeth. In the operating room, general anesthesia was induced with intravenous propofol supplemented with fentanyl. After muscle relaxation was obtained with intravenous vecuronium, direct laryngoscopy was performed with a Macintosh blade. On the first attempt, approaching from the right of her incisor teeth, her tongue could not be appropriately displaced leftward because her loose upper incisors prohibited liberal use of the laryngoscopic blade. Only a part of glottis could been seen (Cormack and Lehane 2grade II) with manual external manipulation of the larynx, and several attempts to put a left-sided endobronchial tube (35-French Bronchocath®; Mallinckrodt Japan, Tokyo, Japan) through her glottis were unsuccessful. Next, we tried the left molar approach because the patient had no left upper teeth with her dentures removed. Because the incisor teeth did not limit the manipulation of the Macintosh blade with this approach, upward force to visualize the glottis could be optimally applied. With external laryngeal manipulation, most of the glottis was visible (Cormack and Lehane grade I). The endobronchial tube was advanced from the left side of the tongue without disturbing the incisor teeth. The tube was successfully placed in her trachea after a couple of attempts to align the tube tip to the glottic opening. Her incisor teeth did not undergo any damage during laryngoscopy and tracheal intubation.

Dental injury is a well-known complication of laryngoscopy and tracheal intubation. Teeth on the patient's right side or in the middle are injured in most cases, with the upper incisors at the highest risk. 3,4To prevent injury, tooth guards or mouth protectors can be used, but they may make the intubation difficult. 5Protectors, which should be attached on the laryngoscope blade, are also reported, 6but they must be prepared beforehand. The left molar approach with a Macintosh blade has the advantages that it may facilitate the laryngoscopic view of the glottis 1and that no special preparation is needed. Considering that avoidance of the maxillary structure may be the reason for an improved glottic view in the left molar approach, 1it is logical that the approach spares the upper incisors at the same time. We conclude that the left molar approach of laryngoscopy may be a good choice when the incisor teeth or teeth on the right side are vulnerable or valuable.

Yamamoto K, Tsubokawa T, Ohmura S, Itoh H, Kobayashi T: Left-molar approach improves the laryngeal view in patients with difficult laryngoscopy. A nesthesiology 2000; 92: 70–4
Cormack RS, Lehane J: Difficult tracheal intubation in obstetrics. Anaesthesia 1984; 39: 1105–11
Gaiser RR, Castro AD: The level of anesthesia resident training does not affect the risk of dental injury. Anesth Analg 1998; 87: 255–7
Warner ME, Benenfeld SM, Warner MA, Schroeder DR, Maxson PM: Perianesthetic dental injuries: frequency, outcomes, and risk factors. A nesthesiology 1999; 90: 1302–5
Aromaa U, Pesonen P, Linko K, Tammisto T: Difficulties with tooth protectors in endotracheal intubation. Acta Anaesthesiol Scand 1988; 32: 304–7
Ghabash MB, Matta MS, Mehanna CB: Prevention of dental trauma during endotracheal intubation. Anesth Analg 1997; 84: 230–1