Measurement · U1NA
U1 to N–A (angle)
Loading the reference ceph.
Definition
Steiner's upper-incisor inclination: the angle between the upper incisor's long axis and the N–A line.
How
Draw N→A and the U1 long axis (U1A→U1T); measure the angle between them (norm ≈ 22°). Read together with the U1–NA mm distance: angle = tip/torque, mm = bodily position.
Purpose
Positions the upper incisor against the maxilla's own diagnostic line. Steiner's treatment goal ('acceptable compromises') was set in exactly these terms — deciding whether to torque, tip, or bodily move the upper incisors.
High
Above the norm reads as proclined upper incisors relative to N–A.
Low
Below the norm reads as upright/retroclined upper incisors relative to N–A.
This is a reviewed tracing on one real cephalogram — the same ceph on every page in Learn — so U1 to N–A (angle) here is a real reading and not a diagram.