Lips measurement
Ricketts E-Line
The esthetic line runs from the nose tip to the chin. Ideally both lips sit behind it — the upper lip about 4 mm and the lower lip about 2 mm, give or take 2 mm. Lips crossing the line read as protrusive; lips far behind it read as flat.
At a glance
- Ideal
- Upper −4 ± 2 mm · Lower −2 ± 2 mm
- Unit
- millimetres
- Weight in the overall score
- 3
- Area
- Lips
How it is measured
Distance of Ls and Li from the Prn–Pog line (negative = behind)
- Prn Pronasale (nose tip) — The most forward point of the nasal tip.
- Pog Pogonion — The most forward point of the chin.
- Ls Labrale superius (upper lip) — The most forward point of the upper lip.
- Li Labrale inferius (lower lip) — The most forward point of the lower lip.
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 0 at the far end of the worst tier.
| Tier | Range | Rating |
|---|---|---|
| T1 Ideal | −6.0 to −2.0 mm | 9.5–10 |
| T2 Acceptable | −8.0 to −6.0 mm or −2.0 to 0.0 mm | 4.3–9.5 |
| T3 Poor | < −8.0 mm or > 0.0 mm | 0–4.3 |
| Tier | Range | Rating |
|---|---|---|
| T1 Ideal | −4.0 to 0.0 mm | 9.5–10 |
| T2 Acceptable | −6.0 to −4.0 mm or 0.0–1.0 mm | 4.3–9.5 |
| T3 Poor | < −6.0 mm or > 1.0 mm | 0–4.3 |
Differences between populations
Optional population norms move this range by the difference reported between groups measured the same way:
- East Asian: upper lip men +6 mm, women +6.5 mm; lower lip +5.5 mm.
- African descent: upper lip +4.5 mm; lower lip +4 mm.
Individual faces vary far more within any group than between groups; these are averages, not targets.
Related measurements
References
- Ricketts RM. Esthetics, environment, and the law of lip relation. Am J Orthod. 1968;54(4):272–289.