Measurement · U1OP
U1 to occlusal plane
Loading the reference ceph.
Definition
The angle between the upper incisor's long axis and the occlusal plane.
How
Draw the occlusal plane (from the incisal overlap point — midpoint of the upper and lower incisal tips — back to the posterior occlusal contact OP) and the U1 long axis; measure the angle between them (norm ≈ 65°, i.e. the incisor meets the biting plane obliquely).
Purpose
Reads incisor inclination against the functional (biting) plane rather than a skeletal base — useful for planning incisor display and anterior guidance after leveling.
High
Above the norm reads as the incisor stands more perpendicular to the biting plane (upright/retroclined crown).
Low
Below the norm reads as the incisor meets the plane more obliquely (proclined crown).
This is a reviewed tracing on one real cephalogram — the same ceph on every page in Learn — so U1 to occlusal plane here is a real reading and not a diagram.