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CEPHALOMETRIC LANDMARKS
Na (nasion): the most anterior point of the fronto-nasal suture.
Ba (basion): the most anterior-inferior point of foramen magnum.
Po (porion): the most superior point of EAM.
Or (orbitale): the most inferior point of the external margin of the orbit.
ANS : the most anterios point of ANS.
PNS : the most posterior point of PNS.
A : the most posterior point of the maxillary concavity.
B : the most posterior point of the mandibular concavity.
Pg (pogonion): the most anterior point of the mandibular symphysis.
Pm (suprapogonion): between Pg and B.
Gn (gnation): the most anterior-inferior point of the mandibular symphysis.
Me (menton): the most inferior point of mandibular symphysis.
Go (gonion): the most posterior-inferior point of the mandible at the gonial angle level. (lo trovi
tracciando le tangenti al posterior border of the ascending ramus e all’inferior border of the body
of the mandible rispettivamente e tracciando poi la perpendicolare al loro punto di incontro sulla
mandibola).
Pt (pterygoid): the most posterior-superior point of the pterygopalatine fossa.
Ag (antegonion): the highest point of antegonial notch.
STEINER ANALYSIS
S : midpoint of sella turcica.
L : punto di incontro tra SN line e la perpendicolare che passa per Pg sulla SN line.
E : punto di incontro tra SN line e la perpendicolare che passa per il più posterior point of the
condyle of the mandible).
D : midpoint of the mandibular symphysis.
Mandibular plane : Go-Gn.
Skeletal analysis
Antero-posterior position of maxilla (relationship maxilla-cranial base)
S𝑁𝑎
A=82°∓2° class I
S𝑁𝑎
A > 8 4 ° class II (maxillary origin) (max prognatism)
S𝑁𝑎
A < 8 0 ° class III (maxillary origin) (max retrognathia)
Antero-posterior position of mandible (relationship mandible-cranial base)
S𝑁𝑎
B =80°∓2° class I
S𝑁𝑎
B > 8 2 ° class III (mandibular origin)^ (mand progn.)
S𝑁𝑎
B < 78 ° class II (mandibular origin)^ (mand retrogn.)
S𝑁𝑎
𝐷 =76°∓2° class I
S𝑁𝑎
𝐷 > 76° class III (mandibular origin)
S𝑁𝑎
𝐷 < 76° class II (mandibular origin)
Linear measurements
ES= 22∓2 mm
SL=51∓2 mm
Antero-posterior relationship maxilla-mandible
A𝑁𝑎
B=2°∓1° class I
A𝑁𝑎
B > 3° class II skeletal
A𝑁𝑎
B < 1° class III^ skeletal
Vertical relationship mandible-cranial base
Mandibular plane-SN line angle=32°∓2° mesofacial
Mandibular plane-SN line angle > 34° dolichofacial
Mandibular plane-SN line angle < 30° brachyfacial
Relationship occlusal plane-cranial base
Occlusal plane-SN line angle=14°∓2° normal
Occlusal plane-SN line angle > 14° inclined plane
Occlusal plane-SN line angle < 14° straight plane
XY axis
Union between S and Gn
Na𝑆
Gn=66° normal
Na𝑆
Gn > 66° dolichofacial
Na𝑆
Gn < 66° brachyfacial
Teeth analysis
Angular measurements
Trace the axis of the upper and lower incisors
UI-NA=22°∓2°
LI-NB=25°∓2°
normal
If > buccal inclination
If < lingual inclination
Down’s interincisal angle
135° - > bi-retrusion
<127° - > bi-protrusion
Linear measurements
Trace the most buccal point of the crown of upper and lower incisors
Distance of this point from NaA in upper
incisors=4∓1 mm
Distance of this point from NaA in lower
incisors=4∓1 mm
normal
If > protrusion
If < retrusion
Profile analysis
Line from S point of the nose to Dt (soft tissue of the chin).
If the lips are to the left of the line - > retrusion
Upper first molar position :
distance from distal of upper
first molar and VPt line
Age+3mm ∓ 3mm - > class I
molar
If > - > class II upper molar
If < - > class II lower molar
Lower lip protrusion : distance
from LI to En-Dt line
- 2 ∓2mm If > - 2 - > lip retrusion
If <- 2 - > lip protrusion
RELATION MEASURE NORMAL VALUES
Maxilla-cranial base S𝑁𝑎
A (Steiner) 82°∓2° - > class I, II, III
Mandible-cranial base S𝑁𝑎
B (Steiner)
Facial axis (Ricketts)
Mandibular plane (Steiner)
80°∓2° - > class I, II, III
90°∓3° - > facial pattern
32°∓2° - > facial pattern
Maxilla-mandible A𝑁𝑎
B (Steiner)
Lower facial height (Ricketts)
2°∓1° - > class I, II, III
47°∓4° - > facial pattern
Mandibular arch Mandibular arch (Ricketts) 26°∓4° - > facial pattern
Superior arch-maxilla Distance of the most buccal
point of the upper incisor
from NaA (Steiner)
Inclination of upper incisor
(Steiner)
4mm∓1mm - > protrusion or
retrusion
22°∓2° - > buccal or lingual
Inferior arch-mandible Distance of the most buccal
point of the lower incisor from
NaB (Steiner)
Inclination of lower incisor
(Steiner)
4mm∓1mm - > protrusion or
retrusion
25°∓2° - > buccal or lingual
Superior-inferior arches Down’s interincisal angle 131°∓4° - > bi-retrusion or bi-
protrusion
Soft tissue profile Distance between lower
incisor and aesthetic line
Protrusion or retrusion of the
lips
INTERPRETATION
- Skeletal class and origin: facial deepness for the position of the mandible and maxillary
deepness (angle between Frankfurt plane and Na-A kine)
- Skeletal pattern
- Upper incisor position and inclination
- Lower incisor position and inclination
- Aesthetic upper lip and lower lip
The normal one should be 90°∓3°
If > - > maxillary retrusion
If < - > maxillary protrusion
