Unit 5 of 7
The dentition
Four incisor points, two molar edges, and what the teeth are doing about the skeleton.
The card
The skeleton sets the problem and the teeth answer it — usually by leaning. Each incisor takes two points, a tip and an apex, because what is being measured is an axis rather than a position. The two molar edges give the back of the occlusal plane.
- Take the more anterior of the two centrals every time, upper and lower, so the axis means the same thing on every ceph.
- The apex is the end of the canal, not the end of the visible shadow — stopping short shortens the axis and flattens the angle.
- U1 to the palatal plane and IMPA are the two inclinations that matter, and they are measured against planes you already own.
- The molar edges give the occlusal plane its back end, which is what makes the Wits appraisal computable.
What you will place