Figure 3. Effects of helical axis parameters on contact shape. Occlusal contacts are shown for a 2.3° rotation of the mandible from maximum intercuspation based on the standard helical axis parameters and helical axis parameters calculated from 0.5°, 0.7°, 1.0° and 1.5° of jaw rotation. We calculated contacts by identifying the points on the aligned computer models of the maxillary and mandibular casts that were within 0.050 mm of each other. Contacts are shown as black regions on the occlusal surfaces of the teeth, and are identified by the black ovals on the full-arch standard image. Seven contacts were identified for the standard helical axis alignment of the casts. Visually, there is little difference between the contacts for the helical axis parameters calculated from 0.7° and larger jaw rotations.