Intelligence artificielle en céphalométrie, atouts et limites
Comment l’intelligence artificielle détecte les points céphalométriques, ses performances, ses pièges et pourquoi le praticien doit vérifier chaque point.
Online cephalometric analysis: Steiner and Tweed
Place the landmarks on your lateral cephalogram: SNA, SNB, ANB, FMA, IMPA, FMIA and the other measurements are calculated instantly, with their interpretation.
- Free
- No sign-up
- Your radiograph stays on your computer
Drop a lateral cephalogram here
JPG or PNG. The image is read by your browser and is not sent anywhere.
How to perform an online cephalometric analysis
- Load the lateral cephalogram (JPG or PNG), or try the example tracing.
- Calibrate if you want the measurements in millimeters: click both ends of the ruler on the radiograph and enter the distance.
- Place the landmarks in the suggested order: the instructions give the definition of each one. Zoom in for greater precision.
- Read the results: each measurement is compared with its norm, and the summary shows the skeletal class, the facial divergence and the Tweed target.
The cephalometric landmarks to place
| Landmark | Name | Definition |
|---|---|---|
| S | Sella | Center of the sella turcica |
| N | Nasion | Most anterior point of the frontonasal suture |
| A | Point A | Deepest point of the anterior concavity of the maxilla |
| B | Point B | Deepest point of the anterior concavity of the symphysis |
| Po | Porion | Highest point of the external auditory meatus |
| Or | Orbitale | Lowest point of the orbital rim |
| Go | Gonion | Most posterior and inferior point of the mandibular angle |
| Gn | Gnathion | Point on the symphysis between Pogonion and Menton |
| Me | Menton | Lowest point of the symphysis |
| UIE / UIA | Upper incisor | Incisal edge, then apex, for the long axis of the tooth |
| LIE / LIA | Lower incisor | Incisal edge, then apex, for the long axis of the tooth |
| UIL / LIL | Labial surfaces (optional) | Most labial points of the crowns, for U1-NA and L1-NB in mm |
The calculated measurements and their norms
The reference values are the usual means of the Steiner and Tweed analyses. They vary with the author, the patient’s age and ethnic background: they guide the reading, they do not make the diagnosis.
| Measurement | What it assesses | Reference value |
|---|---|---|
| SNA | Position of the maxilla relative to the cranial base | 82° ± 2° |
| SNB | Position of the mandible relative to the cranial base | 80° ± 2° |
| ANB | Discrepancy between the jaws: skeletal Class I, II or III | 2° ± 2° |
| SN-GoGn | Facial divergence according to Steiner | 32° ± 5° |
| U1-NA (° and mm) | Inclination and position of the upper incisor | 22° ± 2° and 4 mm ± 1 |
| L1-NB (° and mm) | Inclination and position of the lower incisor | 25° ± 2° and 4 mm ± 1 |
| Interincisal angle | Angle between the long axes of the incisors | 131° ± 5° |
| FMA | Frankfort–mandibular plane angle (divergence according to Tweed) | 25° ± 3° (22 to 28°) |
| IMPA | Lower incisor to mandibular plane | 88° ± 3° |
| FMIA | Lower incisor to Frankfort plane (180 − FMA − IMPA) | 67° ± 3° |
Next step: calculate Steiner’s chevrons from ANB, U1-NA and L1-NB. Further reading, in French: the Steiner analysis step by step, the Tweed triangle and what AI changes in cephalometrics.
Frequently asked questions
Is my radiograph sent to a server?
No. The image is opened directly by your browser and is not sent anywhere: the calculations run on your computer. Still, use an image without the patient’s name if you share it afterwards.
Which image formats are accepted?
JPG and PNG images (and most formats your browser can read). A DICOM radiograph must first be exported to JPG or PNG from your imaging software.
Why calibrate?
Angles do not depend on the image scale, but distances (U1-NA and L1-NB in millimeters) do. Calibration means clicking both ends of a known distance, for example the ruler visible on the cephalogram, then entering its length.
Which norms does the tool use?
The usual mean values of the Steiner and Tweed analyses, listed in the table above. They vary with the author, age and ethnic background: interpretation remains the practitioner’s.
Can it be used for teaching?
Yes, that is what it is designed for: free and with no sign-up, it lets a student practice landmark identification and immediately see the effect of a misplaced landmark on the measurements.
Does the tool replace cephalometric software?
No. It is a learning and quick-check tool. In GS Ortho, AI places 29 landmarks automatically (including the soft-tissue profile), the tracing is saved in the patient’s record and the measurements feed into the diagnosis.
Our cephalometrics guides (in French)
Analyse de Tweed et triangle FMA, IMPA, FMIA en orthodontie
Comprendre l’analyse de Tweed, FMA, IMPA et FMIA, valeurs de référence, lecture de la divergence et lien avec l’encombrement et la décision d’extraction.
Analyse de Steiner en céphalométrie, mesures et interprétation
L’analyse de Steiner pas à pas, points, plans, SNA, SNB, ANB, position des incisives, valeurs moyennes, limites de l’ANB et apport du Wits en pratique.