1usenaangleskullxr
This test measures the angle between the upper front tooth and a line connecting the skull base landmarks on a skull X-ray, used to evaluate jaw relationship and facial growth.
{"Measures the angle between upper incisor and sella-nasion line on skull X-ray","Helps assess jaw alignment and facial growth pattern","Used in orthodontics and oral surgery treatment planning","Normal angle ranges from 82-84 degrees in adults","Abnormal angles may indicate jaw protrusion or retrusion"}
Key facts at a glance
- LOINC
- 60611-1
- Short code
- UCI-SN Angle
- Synonyms
- 1U-SeNa Angle Skull XR
- Category
- chemistry
- Sample
- serum
- Container
- Not applicable (imaging study)
- Units
- N/A
- Ref low
- 102
- Ref high
- 110
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- xr-measured
- CPT
- 70350
- SNOMED
- 3631008
- Specimen volume
- Not applicable (radiographic imaging)
- Stability
- Not applicable (imaging study)
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 1–24 hours
- Order
- routine
What is this test?
The Sella-Nasion to Upper Incisor (SNA) angle test is a cephalometric analysis performed on a skull X-ray (cephalogram). It measures the angle formed between the line connecting the sella (center of the pituitary gland) to the nasion (bridge of the nose) and a line drawn through the upper central incisor tooth. This measurement helps dentists and oral surgeons understand the positional relationship of the upper jaw to the skull base.
During the test, a specialized X-ray machine takes a side-view image of your head. The dentist or orthodontist then uses specific landmarks on the X-ray to draw lines and measure the angle. This is a routine diagnostic procedure in orthodontic treatment and jaw surgery planning.
Reference range
Normal angle typically ranges from 102° to 110° in Caucasian adults; may vary by ethnicity and population normsN/A
Patient should remove all metallic objects, jewelry, and dental appliances before X-ray exposure. Inform patient about radiation exposure precautions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The SNA angle is a key measurement in orthodontics and oral-maxillofacial surgery. A normal SNA angle ranges from 82-84 degrees in adults. An angle greater than 84 degrees may indicate maxillary protrusion (upper jaw too far forward), while an angle less than 82 degrees suggests maxillary retrusion (upper jaw too far back). This information helps in diagnosing malocclusions, planning orthodontic treatment, and determining if jaw surgery is necessary.
This test is also important for monitoring facial growth in children and adolescents, evaluating treatment outcomes, and assessing sleep apnea patients. The measurement is often used together with other cephalometric angles (such as SNB and ANB) to get a complete picture of jaw relationships.
Frequently asked questions
Does this test require blood draw?
Is the X-ray safe?
How long does the test take?
Do I need to prepare anything before the test?
Sources
- 1
- 2
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.
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