SNB Angle
Pronunciation: S-N-B angle
Also written as: SNB — Sella-Nasion-B Point Angle
A cephalometric measurement expressing the anteroposterior position of the mandibular base relative to the cranial base. It is read in conjunction with SNA to determine skeletal discrepancy.
Full Definition
The SNB angle is measured on a lateral cephalogram from the sella turcica (S) through nasion (N) to point B, the deepest point on the anterior surface of the mandibular symphysis. A normative value of approximately 78° is accepted in many analyses. Values below this suggest mandibular retrusion; values above suggest mandibular prognathism. When editing orthodontic reports, SNB must always appear alongside SNA and the ANB difference. It should be styled as a three-letter uppercase abbreviation followed by the degree symbol and numeral.
Usage
Usage note: Always capitalise all three letters. Do not expand to 'sella-nasion-B' in body text unless in a methodology section; the abbreviation is standard in clinical prose.
In Context
- "The patient's SNB angle of 74° confirmed significant mandibular retrusion relative to the cranial base." — Clinical case report
- "Editors should verify that SNB values are presented to one decimal place and followed by the degree symbol." — Style guide note