Steiner Analysis
The Steiner analysis is a cephalometric method developed by Dr. Cecil C. Steiner and presented in 1953. It was one of the first analyses to use the Sella-Nasion (S-N) line — a reference formed by two points inside the skull base — instead of the Frankfort Horizontal plane used by earlier methods. Because the S-N line proved highly reproducible and stable across patients, Steiner's approach became, and remains, the most widely taught cephalometric analysis in orthodontic education worldwide.
Steiner organized his method into three parts: a skeletal analysis (how the jaws relate to the skull and to each other), a dental analysis (how the incisors relate to their supporting jaws), and a soft-tissue analysis (the profile of the lips and chin). This structure makes it a practical, chairside framework for diagnosing anteroposterior (front-to-back) skeletal and dental discrepancies.
What It Evaluates
Steiner's analysis answers three core diagnostic questions: Is the maxilla positioned normally relative to the cranial base? Is the mandible positioned normally relative to the cranial base? And how do the two jaws relate to each other? It then extends this skeletal picture to the incisors, checking whether the upper and lower teeth are angled and positioned correctly over their respective jaw bones, and finally looks at the soft-tissue profile to judge overall facial balance.
Learn more: Steiner Analysis — Skeletal, Dental, and Soft-Tissue Framework
Key Measurements
- SNA — the angle between the S-N line and point A (the deepest point on the maxillary bone), describing how far forward or back the maxilla sits relative to the skull base. Normal value: 82° ± 2°.
- SNB — the angle between the S-N line and point B (the deepest point on the mandibular bone), describing the anteroposterior position of the mandible. Normal value: 80° ± 2°.
- ANB — the difference between SNA and SNB, summarizing the sagittal relationship between the two jaws. Normal value: 2° ± 2°. Values above 4° suggest a skeletal Class II tendency (mandible relatively behind the maxilla); values below 0° suggest a skeletal Class III tendency (mandible relatively ahead of the maxilla).
- U1-NA (angle and distance) — the inclination and forward protrusion of the upper incisor relative to the N-A line. Normal values: 22° ± 2° and 4 mm ± 2 mm.
- L1-NB (angle and distance) — the inclination and forward protrusion of the lower incisor relative to the N-B line. Normal values: 25° ± 2° and 4 mm ± 2 mm.
- Interincisal angle (U1-L1) — the angle between the long axes of the upper and lower incisors, reflecting overall incisor proclination. Normal value: 131° ± 6°.
- Pog-NB distance — how far the chin (Pogonion) sits relative to the N-B line, used to judge chin prominence. Normal range: 1-4 mm.
Learn more: Steiner's Cephalometric Analysis — Measurement Breakdown
Clinical Interpretation
An orthodontist reads Steiner's numbers as a chain: SNA and SNB first establish where each jaw sits individually, and ANB then tells the story of how they relate to each other. A high ANB with a normal SNA but low SNB points to a retrusive (underdeveloped or set-back) mandible, while a low or negative ANB with a normal SNB but high SNA suggests a maxilla that is too far forward, or a genuinely prognathic mandible. The incisor angles are then checked against this skeletal base — for example, a large U1-NA angle indicates upper incisors that are proclined (tipped forward) rather than upright, which may be compensating for an underlying skeletal discrepancy rather than reflecting the true jaw relationship. This distinction between skeletal and dental compensation is central to deciding whether a case can be treated with tooth movement alone or requires growth modification or surgical input.
Learn more: Steiner's Analysis Explained