Measurement · SCONVEX
Soft-tissue facial convexity (N′-Sn-Pog′)
Loading the reference ceph.
Definition
How much the soft-tissue profile bends at Subnasale: the angle between the upper-face line (N′→Sn) extended and the lower line Sn→Pog′. (Glabella is classic for the upper ray; soft Nasion is used here — approximate.)
How
Draw N′–Sn and Sn–Pog′. Extend N′–Sn beyond Sn; the deviation of Sn→Pog′ from that extension is the convexity (0° = straight profile; positive = convex).
Purpose
The whole-profile verdict in soft tissue — the number that matches what you see standing at the chairside. Convex reads Class II, concave Class III, regardless of what the skeleton is doing under compensated lips.
High
Above the norm reads as a convex soft-tissue profile (Class II facial appearance).
Low
Below the norm reads as a straight-to-concave profile (Class III facial appearance).
This is a reviewed tracing on one real cephalogram — the same ceph on every page in Learn — so Soft-tissue facial convexity (N′-Sn-Pog′) here is a real reading and not a diagram.