Measurement · PFHAFH
Posterior:anterior face height ratio (S-Go : N-Me)
Loading the reference ceph.
Definition
Posterior face height (Sella→Gonion) as a percentage of anterior face height (Nasion→Menton). Jarabak's facial-height ratio (norm ≈ 62–65%).
How
Measure S→Go and N→Me; report S-Go ÷ N-Me × 100.
Purpose
The cleanest single predictor of growth rotation: below ~59% the posterior face is losing the race (clockwise/vertical rotation, open-bite trend); above ~65% posterior height dominates (counterclockwise/horizontal rotation, deep bite). Watching it across visits shows which way the face is actually rotating.
High
Above the norm reads as posterior height dominant (>65%) — horizontal/counterclockwise grower, deep-bite tendency.
Low
Below the norm reads as posterior height deficient (<62%) — vertical/clockwise grower, open-bite tendency.
This is a reviewed tracing on one real cephalogram — the same ceph on every page in Learn — so Posterior:anterior face height ratio (S-Go : N-Me) here is a real reading and not a diagram.