Steiner analysis explained: measurements, norms and how to read them
Key points
- The Steiner analysis relates the jaws, the incisors and the soft tissue profile to the S-N line, from sella to nasion.
- Its best-known readings are SNA, SNB and their difference, ANB.
- Steiner’s mean values include SNA 82°, SNB 80° and ANB 2°, with the upper incisor 4 mm ahead of N-A at 22° and the lower incisor 4 mm ahead of N-B at 25°.
- Steiner presented these values as averages to be adjusted for the individual, not as numbers every patient should match.
What the Steiner analysis is
Cecil Steiner described his cephalometric analysis in 1953 [1] and wrote about its clinical use in 1959 and 1960 [2, 3]. He brought together a small set of readings that are quick to take on a lateral cephalogram. Steiner credited many of them to earlier authors, among them Downs, Riedel, Thompson, Wylie and Holdaway [2].
Most readings are taken from the S-N line, which runs from the centre of sella turcica (S) to nasion (N), the front of the frontonasal suture. The analysis has three parts: skeletal, dental and soft tissue.
Landmarks and lines
- A point: the deepest point on the front of the maxilla, between the anterior nasal spine and the upper incisor.
- B point: the deepest point on the front of the mandible, between the lower incisor and the chin.
- Pogonion (Pog): the most anterior point of the bony chin.
- Gonion (Go) and gnathion (Gn): the angle of the mandible and the lowest front point of the chin. The line Go-Gn is Steiner’s mandibular plane. Steiner noted that both points are hard to locate [2].
- D point: the centre of the cross-section of the symphysis, leaving out the alveolar process. Steiner added it in 1959 [2].
- Lines N-A and N-B: from nasion through A point and through B point. The incisors are measured against them.
The measurements
Skeletal
- SNA: the angle between S-N and N-A. It describes the front-to-back position of the maxillary apical base relative to S-N.
- SNB: the angle between S-N and N-B, the same for the mandibular apical base.
- ANB: SNA minus SNB, the angle between N-A and N-B. It compares the two apical bases with each other.
- SND: the angle between S-N and N-D. Steiner proposed it in 1959 as a measure of the position of the mandible as a whole [2].
- Occlusal plane to S-N and Go-Gn to S-N: the inclination of the occlusal plane and of the mandibular plane.
Dental
- Upper incisor to N-A: the angle between the long axis of the upper central incisor and N-A, and the distance from its labial surface to N-A in millimetres.
- Lower incisor to N-B: the same for the lower central incisor and N-B.
- Interincisal angle: the angle between the long axes of the upper and lower central incisors.
- Pogonion to N-B: the distance of the chin from N-B. Steiner reported Holdaway’s view that this distance and the lower incisor to N-B distance should ideally be equal [2].
Soft tissue
The S-line, described by Steiner, runs from soft tissue pogonion to the midpoint of the S-shaped curve between subnasale and the tip of the nose (pronasale) [4]. The distance of the most prominent point of each lip from this line is measured in millimetres.
Steiner’s values and their sources
| Measurement | Steiner’s value | Source |
|---|---|---|
| SNA | 82° | Steiner 1959, chart [2]; Jha [5] |
| SNB | 80° | Steiner 1959, chart [2]; Jha [5] |
| ANB | 2° | Steiner 1959, text [2] |
| SND | 76° | Jha [5] |
| Occlusal plane to S-N | 14° | Steiner 1959, chart [2]; Jha [5] |
| Go-Gn to S-N | 32° | Jha [5] |
| Upper incisor to N-A | 4 mm, 22° | Steiner 1959, text [2] |
| Lower incisor to N-B | 4 mm, 25° | Steiner 1959, text [2] |
| Interincisal angle | 131° | Jha [5] |
| Pogonion to N-B | No fixed value; equal to lower incisor to N-B | Holdaway, in Steiner 1959 [2] |
| Upper and lower lip to S-line | 0 mm | Jha [5] |
“Text” means the value is stated in the body of Steiner’s 1959 paper; “chart” means it is printed in that paper’s cephalometric appraisal chart. “Jha” means the value is listed as Steiner’s in a 2021 study that compared its sample with Steiner’s values; we could not read it in Steiner’s own papers.
Steiner gave single mean values, without standard deviations. He described them as his concept of “a normal average American child of average age”, and wrote that they can and should be varied for the individual [2].
The incisor values and ANB fit together. The interincisal angle equals 180° minus the upper incisor to N-A angle, the lower incisor to N-B angle and ANB. With Steiner’s values that gives 180 − 22 − 25 − 2 = 131°.
Worked example
These readings are invented for this example; they are not from a patient. Each one is compared with Steiner’s value.
| Measurement | Reading | Steiner’s value | Difference |
|---|---|---|---|
| SNA | 84° | 82° | +2° |
| SNB | 79° | 80° | −1° |
| ANB | 5° | 2° | +3° |
| Upper incisor to N-A | 6 mm, 27° | 4 mm, 22° | +2 mm, +5° |
| Lower incisor to N-B | 7 mm, 31° | 4 mm, 25° | +3 mm, +6° |
| Interincisal angle | 117° | 131° | −14° |
| Pogonion to N-B | 1 mm | Equal to lower incisor to N-B | 1 mm vs 7 mm |
- ANB is SNA minus SNB: 84 − 79 = 5°, which is 3° above Steiner’s value.
- Both incisors are further forward and more inclined to their lines than Steiner’s values.
- The interincisal angle follows from the other readings: 180 − 27 − 31 − 5 = 117°.
- The chin is 1 mm ahead of N-B and the lower incisor 7 mm, so the two distances are not equal as in Holdaway’s 1:1 comparison.
The table describes how far each reading is from Steiner’s value. On its own, it does not say why. The limits below explain why a single reading, ANB in particular, can mislead.
Limits of the Steiner analysis
- ANB depends on more than the jaws. Hussels and Nanda showed that ANB changes with rotation of the jaws or the occlusal plane relative to S-N, with the front-to-back position of nasion, with vertical growth and with dental height. In their calculations, ANB varied widely even when the jaws were in the same Class I relation [6].
- Another view of the same question. Jacobson’s Wits appraisal avoids nasion. It projects A and B onto the occlusal plane. In adults with excellent occlusion the two points coincided on average in females, and B was 1 mm ahead of A in males [7].
- Populations differ. Kuwaiti adolescents differed from white adolescents in most of the measurements tested, with fuller lips, greater dental protrusion and a more retruded mandible; SNA did not differ [8]. Adults from Bihar, India, had a mean interincisal angle of 121° against Steiner’s 131° [5]. Steiner’s values come from his own concept of an average American child [2].
- Landmarks are not always clear. Steiner himself noted that gonion and gnathion are hard to locate [2]. A small error in a point changes every angle that uses it.
- Treatment planning is outside this article. Steiner also published charts of incisor positions for ANB values other than 2° [2]. They are part of planning treatment and are not covered here.
Do this in Simplified Ceph
Simplified Ceph includes the Steiner analysis: skeletal, dental and soft tissue readings on the S-N line, with SNA, SNB, ANB and the incisor angles and distances. You place the landmarks on a lateral cephalogram, and each reading is shown next to its published norm. There is a Free plan for lateral cephalometric analysis.
Educational content for clinicians and students. Reference values vary between populations. This page does not replace clinical judgement.
References
- Steiner CC. Cephalometrics for you and me. Am J Orthod. 1953;39(10):729-55. doi: 10.1016/0002-9416(53)90082-7
- Steiner CC. Cephalometrics in clinical practice. Angle Orthod. 1959;29(1):8-29. Publisher’s page
- Steiner CC. The use of cephalometrics as an aid to planning and assessing orthodontic treatment. Am J Orthod. 1960;46(10):721-35. doi: 10.1016/0002-9416(60)90145-7
- Singh AV, Mahamuni A, Gaharwar JS, Rai R, Yadav K, Sirishkusum C. Evaluation of change in the facial profile and aesthetics in relation to incisor position in both maxillary and mandibular arches. Cureus. 2023;15(1):e34403. doi: 10.7759/cureus.34403. PMID: 36874653
- Jha MS. Cephalometric evaluation based on Steiner’s analysis on adults of Bihar. J Pharm Bioallied Sci. 2021;13(Suppl 2):S1360-4. doi: 10.4103/jpbs.jpbs_172_21. PMID: 35017989
- Hussels W, Nanda RS. Analysis of factors affecting angle ANB. Am J Orthod. 1984;85(5):411-23. doi: 10.1016/0002-9416(84)90162-3. PMID: 6586080
- Jacobson A. The “Wits” appraisal of jaw disharmony. Am J Orthod. 1975;67(2):125-38. doi: 10.1016/0002-9416(75)90065-2. PMID: 1054214
- Behbehani F, Hicks EP, Beeman C, Kluemper GT, Rayens MK. Racial variations in cephalometric analysis between Whites and Kuwaitis. Angle Orthod. 2006;76(3):406-11. PMID: 16637719