Skip to content

Anbangleskullxr

Published: August 9, 2026Updated: August 16, 2026

The SNB angle is a measurement taken from a skull X-ray (cephalogram) to evaluate the position of the lower jaw relative to the upper jaw and facial structure.

Quick summary

{"Measures the angle between the nose bridge, chin point, and base of the skull","Helps orthodontists assess jaw alignment and facial growth","Used to diagnose overbite, underbite, and other bite problems","Guides treatment planning for braces, aligners, or jaw surgery","A normal SNB angle typically ranges between 78-82 degrees"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
32928-4
Short code
ANB Angle Skull XR
Synonyms
ANB Angle Skull XR
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-measured
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

The SNB angle (Sella-Nasion-B point angle) is a measurement taken from a special X-ray called a cephalogram, which captures a side view of the skull and face. This test measures the angle formed by three key points on the skull: Sella (the center of the skull base), Nasion (the bridge of the nose), and B-point (the deepest part of the lower jaw). It helps doctors see how the lower jaw is positioned compared to the upper jaw and the rest of the face.

How is the test performed?

You will be positioned in front of a cephalometric X-ray machine with your head held steady by a special support. The machine will take a side-view X-ray of your skull and jaw. The entire process takes only a few seconds and is painless. The resulting image allows the orthodontist or oral surgeon to draw lines and measure specific angles to analyze your jaw structure.

Why is this test important?

The SNB angle helps healthcare providers understand the relationship between your upper and lower jaws. This information is crucial for planning orthodontic treatment, evaluating facial growth in children and teenagers, and determining if jaw surgery may be needed. It provides a precise, objective measurement that goes beyond what can be seen by simply looking at the face.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings2

Frequently asked questions

Does the X-ray expose me to harmful radiation?
The radiation exposure from a cephalogram is very low, similar to the amount you might receive from natural background radiation over a few days. Modern digital X-ray equipment further minimizes exposure. The benefits of getting an accurate diagnosis far outweigh the minimal risks.
Who needs this test?
This test is commonly ordered for patients undergoing orthodontic treatment, those with jaw alignment issues, people considering jaw surgery, and children whose facial growth is being monitored. Your orthodontist or oral surgeon will determine if this test is necessary for your specific case.
How long does it take to get results?
The X-ray itself takes only seconds. Your healthcare provider will typically analyze the images during your follow-up appointment, which may be scheduled a few days to a week after the X-ray is taken.
Is the test painful?
No, the cephalometric X-ray is completely painless. You may need to stay still for a few seconds while the image is captured, and a chin rest may feel slightly uncomfortable, but there is no pain involved.
  1. 1
    American Association of Orthodontists - Cephalometric X-raysSource
  2. 2
    Mayo Clinic - Orthodontic TreatmentSource
  3. 3
    National Institutes of Health - Cephalometry in OrthodonticsSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy