The cephalometric chart
1. Sagittal craniofacial relationships:
- The SNA angle: Determines the anteroposterior position of the maxilla/at the base of the skull, average value: 80°+/- 2.
- The SNB angle: Determines the anteroposterior position of the mandible/base of the skull, average value: 78°+/- 2.
- The ANB angle: This is the difference between the two previous angles, determines the skeletal class according to Ballard, average value: 2.5°+/- 2.
- Class I: ANB=2.5°+/- 2.
- Class II: ANB greater than 2.5°+/- 2.
- Class III: ANB less than 2.5°+/- 2 or negative value.
- Glenoid cavity – Sellion: This is the distance between point S and the most distal point of the condyle projected onto the Frankfurt plane, average value: 17 – 18 mm, this measurement specifies the location of the condyle in the sagittal direction / at the base of the skull.
- Sellion – Pterygomaxillary cleft (PMF): This is the distance between point S and the center point of the PMF projected onto the Frankfurt plane, average value: 17 – 18 mm, this measurement specifies the location of the maxilla in the sagittal direction / at the base of the skull.
- SE / SL: these measurements specify the location of the mandible in the sagittal direction / at the base of the skull.
- S/E: This is the distance between point S and the most posterior point of the condyle projected on the SN line, average value: 22 mm.
- S/L: This is the distance between point S and the most anterior point of the mandible projected on line SN, average value: 51 mm.
- Ricketts convexity: This is the distance between Downs point A and its orthogonal projection on the Na-pog facial plane. Average values according to age:
- From 3 to 6 years: 5.5 mm.
- From 7 to 10 years: 4.4 mm.
- From 11 to 14 years: 3.7 mm.
- From 15 to 18 years old: 2.5 mm.
- In adults: 1.7 mm.
These values are given in positive numbers if point A is in front of the facial plane and the bone profile is said to be: convex, and in negative numbers if point A is behind the facial plane and the bone profile is said to be: concave.
2. Basal measurements:
2.1. At the maxillary level:
- FPM-ENA: This is the distance between the ENA point and the center of the FPM projected orthogonally on the Frankfurt plane, average value: 52 mm at 11 years, this measurement specifies the overall length of the maxilla in the sagittal direction.
- A-T of Château: Point T represents the intersection between the bispinal plane and the axis of the FPM, the distance A-T represents the length of the maxilla, Average values according to age:
- 8 years: 46 mm
- 12 years: 49 mm
- 16 years: 51 mm
- In adults: 52 mm.
The cephalometric chart
2.2. At the mandibular level:
- Overall length of the mandible: This is the distance between the most anterior and most posterior points of the mandible projected onto the mandibular plane, Mean value; 103 mm (boys), 101 mm (girls).
- Xi-Pm measurement: Xi: This is the center of the ascending branch of the mandible , Pm: midpoint between Downs’ B and the Pog, the distance between these two points represents the length of the mandible, Average values according to age:
- 9 years : 64-70 mm
- 10 years: 65 – 71 mm
- 11 years: 67-73 mm
- 12 years: 68-74 mm
- 13 years: 70-76 mm
- 14 years: 72-78 mm
3. Growth direction:
3.1. Direction of facial growth:
- Brodie y-axes: This is the antero-inferior angle formed by the Frankfurt plane and the line S – Gn. Average value: 59°
- Ricketts facial axis:
- The Pt (pterygoid) point is located in the middle of the supero-distal quadrant of the FPM
- The intersection of the Pt-Gn line with Na –Ba gives the point cc (center of the skull).
- The facial axis represents the infero-posterior angle formed by the Na-Ba and CC-Gn lines
- Average value: 90°+/-3.
3.2. Direction of mandibular growth:
- Tweed FMA: This is the antero-inferior angle formed by the Frankfurt plane and the mandibular plane. Average value: 27° +/-4.
4. Vertical measurements:
- Anterior facial height: this is the divergence of the two jaws represented by the angle ENA-Xi-Pm. Average value: 47° +/-4.
- Total height of the face: it is measured between the points Na and Me, this height is itself divided into lower and upper floors by a perpendicular from the ENA on the line Na –Me. The proportion of the lower or upper floor is given by the following formula:
Upper floor height / Total facial height x 100.
– Upper floor: 45%
– Lower floor: 55%
- Ramal length: The distance between the two points Co and Go is measured, the latter compared with that of the total facial height given by the Na-Me line. The average value is given by percentage: 47%.
5. Tooth/skeleton ratios:
- Position of the first upper molar (6-PTV) : it is the distance between the distal face of the first upper molar and the tangent of the FPM, it allows to determine the mesio or disto position of the 6 upper. Average value: age of the patient +3 mm +/-3.
- I/F: This is the posteroinferior angle formed by the intersection of the axis of the upper central incisor with the Frankfurt plane; an increased angle indicates a vestibuloversion of the incisor. Average value: 107° +/- 2.
- i/m: it is the posterosuperior angle formed by the intersection of the axis of the lower central incisor with the mandibular plane, an increased angle indicates a vestibuloversion of the incisor. Average value: 107° +/- 2.
- I/A-Pog:
- Angular value: This is the angle formed by the axis of the upper incisor and the A-Pog line. Average value: 26°+/- 4
- Linear value, it is the distance between the free edge of the upper incisor and the A-Pog line. Average value: 2mm +/- 2
- i/A-Pog:
- Angular value: This is the angle formed by the axis of the lower incisor and the A-Pog line. Average value: 22°+/- 4
- Linear value, it is the distance between the free edge of the lower incisor and the A-Pog line. Average value: 1mm +/- 2
- Angle of attack (inter-incisal): Formed by the intersection of the axes of the two upper and lower incisors. Average value: I/i = 125°.
The cephalometric chart
Cephalometric chart table:
| Measurements | Average value | Value found | Interpretation | |
| Sagittal craniofacial relationships | SNA | 80° + 2 | ||
| SNB | 78° + 2 | |||
| ANB | 2° + 2 | |||
| Convexity | According to age | |||
| SE | ||||
| SL | ||||
| S-CG | 17-18 | |||
| S-FPM | 17-18 | |||
| Basal measurements | FPM-ENA | 52mm | ||
| A-T of Chateau | According to age | |||
| WW Length | 101-103mm | |||
| Xi-Pm | Depending on age 68-74mm | |||
| Growth direction | Tweed FMA | 27° + 4 | ||
| Brodie Y Axis | 59° + 2 | |||
| Ricketts facial axis | 90° + 3 |
| Vertical measurements | HES | 45% | ||
| HEI | 55% | |||
| Ramale Height | 47% | |||
| Height facial ant ENA XI PM | 47°+ 4 | |||
| Tooth-skeleton relationships | 6 PTV | Age+3+ 3mm | ||
| I/F | 107° + 2 | |||
| i / M | 90° + 3 | |||
| I / A-Po | 26° + 4 | |||
| I / A-Po | + 2 mm | |||
| i / A-Po | 22° + 4 | |||
| i / A-Po | 1.5 mm + 2 | |||
| Dental-dental reports | I / i | 125° + 6 | ||
| Aesthetic | LS / Line E | – | ||
| LI / Line E | ||||
| Z angle | 78° |
Cephalometric diagnosis:
- The Skeletal Class
- Clinical forms
- Facial typology
- The direction of facial growth
- The direction of mandibular growth
- Associated anomalies
The cephalometric chart
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