[Determination of the distance between the upper incisors and the laryngoscope blade during laryngoscopy: comparisons of the McCoy, the Macintosh, the Miller, and the Belscope blades].

We compared the distance between the upper central incisors and the laryngoscope blade with the four different types of laryngoscope blade (McCoy, Macintosh, Miller, Belscope). Twenty-three patients scheduled for general anesthesia were studied. The tooth-blade distance was measured when optimum visibility of the glottis was obtained. The visibility was determined according to the Cormack and Lehane grading. The distance with the McCoy and the Belscope was greater than that with the Macintosh or the Miller. The visibility grade was significantly worse with the Macintosh than with the other types of laryngoscope. The results indicate that the McCoy and the Belscope provide less incidence of upper dental injuries and greater visibility than either with the Macintosh or the Miller. Furthermore, the force applied to the handle is thought to be smaller with the McCoy than with the Belscope.