Profile measurement
Facial Convexity (Nasion)
Profile convexity using the nasal root instead of the forehead: the angle at subnasale between nasion and chin. It isolates the midface-to-chin relationship.
At a glance
- Ideal
- 163–171°
- Unit
- degrees
- Weight in the overall score
- 3
- Area
- Profile
How it is measured
∠ N–Sn–Pog, measured on the face side
- N Nasion — The deepest point of the dip between the forehead and the bridge of the nose.
- Sn Subnasale — The point where the underside of the nose meets the upper lip.
- Pog Pogonion — The most forward point of the chin.
Ideal range and tiers
Each value falls into a tier (T1 = ideal). Comfortably inside T1 the rating is 10, easing to 9.5 at the edges of the ideal range; beyond it the rating falls with the deviation — fastest in the first tiers outside the ideal — down to −5 (below 0 where the original tier sheet takes points away) at the far end of the worst tier.
| Tier | Range | Rating |
|---|---|---|
| T1 Ideal | 163–171° | 9.5–10 |
| T2 Near ideal | 160–163° or 171–174° | 6.7–9.5 |
| T3 Mild deviation | 158–160° or 174–176° | 4.3–6.7 |
| T4 Moderate deviation | 156–158° or 176–178° | 2.1–4.3 |
| T5 Severe deviation | < 156° or > 178° | −5 to 2.1 |
Related measurements
References
- Legan HL, Burstone CJ. Soft tissue cephalometric analysis for orthognathic surgery. J Oral Surg. 1980;38(10):744–751.