Comparison of cast positions by using four face-bows.

The positions that the maxillary right and left first molars occupy when a maxillary cast is mounted in the three-dimensional space of a semiadjustable articulator (Hanau H2) were studied. Mountings were made by using four face-bows, the Hanau Kinematic Face-bow, the Hanau Facia-bow, the Hanau 159 Earpiece Face-bow, and the Hanau Twirl Earpiece Face-bow. A kinematically determined hinge-axis was used arbitrarily as the baseline for comparisons among the three other bows. Deviations from the baseline were measured along the X, Y, and Z axes by using a contour meter (Fig. 1). The deviations showed great variability (Table I), and because maxillary casts are mounted in relation to anatomic landmarks that differ from subject to subject, it was not possible to establish clinical superiority of one face-bow over another.