Despite progress in intubation techniques, dental trauma is one of the most common complications of general anesthesia. As the flange of the Macintosh blade appears responsible for most dental injuries, we modified the ordinary Macintosh blade by partially removing its flange and evaluated the effectiveness of the modified blade in terms of reducing potential of dental injuries.

Four hundred and eighty-three patients scheduled for elective surgery requiring general anesthesia with endotracheal tube placement were included in this prospective study. Laryngoscopy was performed twice, once using an ordinary Macintosh No. 3 blade and once using the modified Macintosh blade. The modification consisted of reducing the height of the flange by partial removal, as described by Callander et al. When optimum visibility of the glottis was obtained, the distance between the flange of the blade and the upper incisor was measured. We compared blade-tooth distances and laryngoscopic views for the two blades.

The modified blade with low-height flange provided more distance than the ordinary type of blade (P<0.01). The incidence of direct contact between the blade and the upper tooth was 20.3% when the ordinary blade was used, and nearly 80% of these did not involve direct contact when using the modified blade. In addition, the modified blade provided a greater field of view than the ordinary blade (P<0.01).

The modified Macintosh blade used in this study proved to be a useful device, which could reduce dental injuries and provide a better laryngoscopic view during laryngoscopy.