3. Reference points used in Rakosi’s analysis
• N - most anterior point of the frontonasal suture in the
median plane.
• S–geometric center of the pituitary fossa.
• Se Midpoint of entrance to sella-midpoint of the line
connecting the posterior clinoid process and anterior
opening of the sella turcica.
• A point – deepest point in the concavity from the ANS to
the maxillary alveolar process.
• B point– deepest point in the concavity from the chin to
the mandibular alveolar process.
• Pog – most anterior point of the bony chin.
• Me – the most inferior point of the chin
• Gn – point midway between Pogonion and Menton.
4. Reference points used in Rakosi’s analysis
• Ar – Intersection of the posterior border of the ramus
and the inferior border of the cranial base.
• Cd Condylion – most superior point on the head of the
condyle.
• ANS– the anterior tip of the sharp bony process of the
maxilla at the lower margin of the anterior nasal
opening.
• PNS– the posterior spine of the palatine bone
constituting the hard palate.
• Ba – the lowest point on the anterior rim of the foramen
magnum.
5. REFERENCE PLANES USED IN RAKOSI’S
ANALYSIS
• SN plane
• Frankfort plane
• Palatal plane
• Occlusal plane
• Mandibular plane
6. The Rakosi’s analysis can be divided into 3
divisions:
1- analysis of facial skeleton analysis
2- analysis of jaw bones
3- analysis of dento-alveolar relationship
7. Analysis of Facial Skeleton
• Saddle angle
• Articular angle
• Gonial angle
• Facial hieght
• Extent of anterior and posterior cranial
base length.
8. SADDLE ANGLE
Cranial base (saddle) angle (130° ±
5°): The saddle angle is so termed as
the angle’s centres at sella, which is
the midpoint of the sella turcica (Latin
for ‘ Turkish saddle ’ ).
The saddle angle (N - S - Ba) is the
angle formed between the anterior and
posterior cranial base; it is effectively a
measure of the ‘ bend ’ between the
anterior and posterior cranial base.
It is measured as the anterior inferior
angle formed by the intersection of the
SN line, which represents the anterior
cranial base and the S-Ba line, which
represents the posterior cranial base.
9. SADDLE ANGLE
An increased saddle angle indicates a
posterior position of the glenoid fossa and
mandibular condyle, thereby a posteriorly
positioned mandible (mandibular retrognathia)
in relation to the cranial base, unless
compensated by a more acute gonial angle and
increased mandibular length;
conversely, a reduced saddle angle indicates
an anterior position of the glenoid fossa and
mandibular condyle, thereby leading to
mandibular prognathism, unless compensated
by an increased gonial angle and reduced
mandibular length.
(If basion is difficult to identify on a lateral
cephalometric radiograph, articulare may be
used instead; normal value for N-S-Ar is
125°±5°.)
10. ARTICULARE ANGLE
It is formed by joining the points S, Ar, and
Go.
It is the constructed angle between the
upper and lower contours of the facial
skeleton.
It depends on the position of the mandible .
If the mandible is retrognathic, it increases,
and it decreases in cases of prognathic
mandible.
It decreases with anterior positioning of the
mandible, deep bite and mesial migration of
the posterior segment.
Increases with posterior relocation of the
mandible, opening of the bite and distal
deviation of posterior segment.
• Mean value is 143±6°
11. GONIAL ANGLE
This is a measure of the angle formed by the tangents to the body of the mandible and
posterior border of the ramus. It helps to describe the form of the mandible, in particular
the relationship between the ramus and the body. It is highly correlated with the
mandibular plane angle.
It does not only give the form of the mandible but also gives informtion about the
direction of growth of the mandible. An increased gonial angle is associated with
posterior (backward) mandibular growth rotation, and a reduced gonial angle is
associated with anterior (forward) mandibular growth rotation and is favourable
condition for anterior positioning of the mandible using an activator. Mean value is 128±
7°.
12. UPPER AND LOWER GONIAL ANGLES OF JARABAK
The gonial angle may be
divided by a line drawn from
nasion to gonion.
This gives an upper and lower
gonial angle of Jarabak.
The upper angle is formed by
the ascending ramus and the
line joining nasion and gonion.
A larger upper angle indicates
horizontal growth.
• The mean value is 50-55°.
13. UPPER AND LOWER GONIAL ANGLES OF JARABAK
The lower angle is formed by
the line joining nasion and
gonion and the lower border of
the mandible.
A larger lower angle indicates
vertical growth pattern.
• The mean value is 72-75°.
14. SUM OF POSTERIOR ANGLES
Sum of posterior angles is
Saddle angle + Articulare angle
+ Gonial angle:
• If the sum is more than 396°
then it is clockwise direction
of growth.
• If the sum is less than 396°
then it is anticlockwise
direction of growth.
• If the sum is less than 396°
then it is favourable for
functional appliance therapy.
15. FACIAL HIEGHT
POSTERIOR FACIAL
HEIGHT is measured from S
to Go.
It is more in patients having
horizontal growth pattern
than patients having vertical
growth pattern.
ANTERIOR FACIAL
HEIGHT is measured from N
to Me.
It is more in patients having
vertical growth pattern than
patients having horizontal
growth pattern.
16. JARABAK’S RATIO
• It is given by the formula :
Posterior facial height x 100
Anterior facial height
• A ratio of less than 62%
expresses a vertical growth
pattern whereas more than
65% expresses a horizontal
growth pattern.
17. EXTENT OF ANTERIOR CRANIAL BASE LENGTH
It is taken from N to Se.
It is increased in
horizontal growth
pattern and reduced in
vertical growth pattern.
Mean value is 75mm.
18. EXTENT OF POSTERIOR CRANIAL BASE LENGTH
It is measured from S to Ar.
Also called as lateral cranial base
length.
It is based on posterior facial
height and position of the fossa.
Short cranial bases are seen in
vertical growth pattern and
skeletal open bites.
• Mean value is 32-35mm.
19. Analysis of jaw bases
• SNA
• SNB
• BASE PLANE ANGLE
• INCLINATION ANGLE
• EXTENT OF MAXILLARY BASE
• EXTENT OF MANDIBULAR BASE
• LENGTH OF ASCENDING RAMUS
20. SNA angle
• SNA expresses the sagittal
relationship of the anterior limit
of the maxillary apical base to
the anterior cranial base.
• It is large in prognathic maxilla
and small in retruded maxilla.
• Mean value is 82°.
21. SNB angle
• SNB expresses the sagittal
reltionship between the
anterior extent of the
mandibular apical base and
anterior cranial base.
• The mean value is 80 degree.
• It is large with a prognathic
mandible and small with a
retrusive mandible.
22. BASE PLANE ANGLE
The base plane angle is the angle
between the palatal plane and the
mandibular plane.
It is large in vertical growth pattern
and small in horizontal growth
patterns.
• Mean value is 25° .
The base plane angle is divided into
2:
Upper – between the palatal plane
and the occlusal plane. Mean
value is 11°.
lower – between the occusal plane
and the mandibular plane . Mean
value is 14°.
23. INCLINATION ANGLE
It is the angle formed by the
perpendicular line dropped from Se-
N at N‛ and the palatal plane.
A large angle expresses upward and
forward inclination whereas small
angle indicates down and back
tipping of the anterior end of the
palatal plane and maxillary base.
• Mean value is 85° .
Red= anterior rotation
Red= anterior rotation
Blue= posterior rotation
24. LINEAR MEASUREMENT OF THE JAW
BASES
• EXTENT OF MANDIBULAR BASE
• EXTENT OF THE MAXILLARY BASE
• LENGTH OF ASCENDING RAMUS
25. EXTENT OF MANDIBULAR BASE
The extent of the mandibular
base is determined by
measuring the distance
between Go and Pog.
More in patients having
horizontal growth pattern than
patients having vertical growth
pattern.
Ideally it should be 3 mm more
than (N-Se) distance.
26. EXTENT OF MAXILLARY BASE
It is determined by measuring
the distance between the PNS
and a perpendicular drawn
from point A to the palatal
plane.
The difference of the
measurement between
horizontal and vertical growth
pattern is slight.
27. LENGTH OF ASCENDING RAMUS
The length of the ascending
ramus is done by measuring
the distance between the
gonion and the condylion.
The length of the ramus is more
in patients having horizontal
growth pattern than vertical
growth pattern.
28. Linear analysis of the jaw bases
The dimensions of the jaw bases are
assessed in relationship to the N-Se
distance in the form of a
proportional analysis as discribed by
Schwarz.
The ideal value for the length of the
mandibular base in relationship to
ant. Cranial base is 3 mm greater
than the N-Se distance.
The relationship of the upper to
lower jaw base length in in the ratio
of 2:3, and the average relation of the
ramus to mandibular base 5:7.
30. UPPER INCISORS
The long axis of the upper incisors is
extended to intersect the S-N line and
the posterior angle is measured.
It is used to determine the position of
the maxillary incisors.
In cases of proclined upper incisors the
angle increases.
Mean value is 104° .
A smaller angle indicates the incisors
are lingually tipped which is
advantageous for functional appliance
treatment.
31. LOWER INCISORS
The long axis of the lower incisors is
extended to intersect with the
mandibular plane and the posterior
angle is measured.
Smaller angle indicates lingual
tipping of the incisors.
If the lower incisors are labially
tipped, the reposition of the mandible
anteriorly as well as lingually tip the
incisors and these two things are in
the opposite direction so functional
applince therapy ,may be difficult.
• Mean value is 90°±5º.
32. POSITIONS OF INCISORS
Position of the incisors is the
distance of the incisal edges from
the N-Pog line the so called facial
plane.
The average position of the
maxillary incisors is 2 to 4mm
anterior to the N-Pog line
The average position of the
mandibular incisors is 2mm
anterior or posterior to the N-Pog
line.
