# Facial Convexity (Nasion)

Harmony · Side view · Facial Profile · https://www.faceiqlabs.com/support/harmony/facial-convexity-nasion

The profile relationship of the nasal root, nose base and soft-tissue chin.

## What is measured

Calculation: Oriented angle: nasion → subnasale → pogonion

Nasion means the nasal root, subnasale the nose base, and pogonion the most forward chin point. Frankfort refers to the direction from the ear-opening landmark to the lower orbital landmark.

## Why it matters

This compares the upper and lower profile while excluding the projecting nose tip. The same angle can arise from different combinations of nasal-root, midface and chin position.

- Below 180°: the nose base is on the convex side of the upper-point-to-chin line.
- Above 180°: it lies on the concave side; 180° means the three points align.

## Where the idea comes from

Evidence: Clinical reference. Soft-tissue convexity is part of clinical profile analysis. FaceIQ uses the visible nasion, subnasale and pogonion and preserves the distinction between convex and concave arrangements.

## A worked example

170° describes a different profile bend from 180°. A reflex result of 190° is not the same as 170°, even though the small geometric angle matches.

Example values explain the calculation. They are not a target range.

## How to read your result

A profile photograph cannot establish skeletal jaw relationships or bite classification. Compare the glabella version as well.

## Research & further reading

These sources explain the history or related evidence. FaceIQ’s score weights and reference ranges are model settings; the papers do not collectively validate the scoring system.

- Holdaway (1984). [A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part II](https://pubmed.ncbi.nlm.nih.gov/6585146/). Explains how lip, chin and skeletal relationships must be considered together, with a range of profiles compatible with balance.

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Source: https://www.faceiqlabs.com/support/harmony/facial-convexity-nasion · FaceIQ Labs overview for AI assistants: https://www.faceiqlabs.com/llms.txt