Measurement · U1
U1 to palatal plane
Loading the reference ceph.
Definition
The inclination of the upper central incisor to the palatal plane (ANS–PNS): the posterior-superior angle between the incisor's long axis and the plane.
How
Draw the palatal plane (ANS–PNS) and the upper incisor long axis (apex U1A → tip U1T); read the posterior angle where the axis crosses the plane (~110° normally, i.e. the crown tips labially).
Purpose
Reads upper-incisor torque against the maxilla's own reference plane — unaffected by where the maxilla sits. Distinguishes dental compensation (flared or upright incisors masking a skeletal discrepancy) from true skeletal cause.
High
Above the norm reads as proclined (labially tipped) upper incisors — dental protrusion or Class III compensation.
Low
Below the norm reads as retroclined upper incisors — Class II div 2 pattern, or retraction-type compensation.
This is a reviewed tracing on one real cephalogram — the same ceph on every page in Learn — so U1 to palatal plane here is a real reading and not a diagram.