Location of the terminal hinge axis and its effect on the second molar cusp position.

Incorrect location of the terminal hinge axis of 5 and 8 mm to the anterior, posterior, superior, and inferior was examined. With jaw relation records 3 and 6 mm thick at the incisors, the errors in cusp height at the second molar ranged from 0.15 mm open space to 0.4 mm excess height. The mesiodistal error ranged from 0.51 mm toward the distal to 0.52 mm toward the mesial. While the mesiodistal component to the error has been calculated in the past with some accuracy, the values obtained have varied because different anatomic dimensions were used. In addition, the vertical component of the error in cusp height as illustrated in Fig. 2 was not considered and/or not subjected to in-depth calculation.