Abstract
The vertical positions of teeth on mandibular tooth arrangement were measured by newly devised clinical method. Combining the results with the measured data of mesio-distal positions of teeth, the average radius of Spee's curve was obtained by drawing in actual dimensions. As the result, it was shown that the circular arc with the radius of 180 mm matches well with the curve drawn through incisal point, second premolar and second molar, and the circular arc with the radius of 220mm matches well with the curve drawn through incisal point, second premolar and first molar. By this study, the average radius of Spee's curve among Japanese was first measured.
