Point A
A cephalometric landmark (also called subspinale) representing the deepest concavity on the anterior surface of the maxillary alveolar process in the midsagittal plane.
Full Definition
Point A, or subspinale, is identified on a lateral cephalogram as the most posterior point on the concave outline of the maxillary alveolar process between the anterior nasal spine and the alveolar crest of the upper central incisors. It is used in key angular measurements such as the SNA angle and the ANB angle to evaluate maxillary sagittal position relative to the cranial base. Because Point A can be altered by orthodontic tooth movement, some clinicians prefer skeletal landmarks less susceptible to dental change. Editors must render this term as 'Point A' (capital P, capital A) and use 'subspinale' when the full anatomical name is required.
Usage
Usage note: Capitalise both words (Point A); do not abbreviate to 'A' in isolation without defining context. Distinguish from the ANS (anterior nasal spine).
In Context
- "A retrusive Point A value suggested maxillary deficiency as the primary aetiology of the Class III malocclusion." — Cephalometric analysis report
- "The author used Point A rather than the anterior nasal spine to measure the sagittal position of the maxilla." — Peer-reviewed journal article