Rakosis analysis
54
Dr sooraj s pillai 1 st Yr PG.
Transcript of Rakosis analysis
Dr sooraj s pillai
1st Yr PG.
The Rakosis analysis is an important diagnostic
tool in planning functional appliance therapy.
N Nasion - most anterior point of the frontonasalsuture in the median plane.
S Sella –geometric center of the pitutary fossa.
Se Midpoint of entrance to sella - midpoint of the line connecting the posterior clinoid process and anterior opening of the sella turcica.
A Subspinale – deepest point in the concavity from the ANS to the maxillary alveolar process.
B Supramentale – deepest point in the concavity from the chin to the mandibular alveolar process.
Pog Pogonion – most anterior point of the bony chin.
Me Menton – the most inferior point of the chin
Gn Gnathion – point midway between Pogonion and Menton.
Ar Articulare – 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 Anterior nasal spine – the anterior tip of the sharp bony process of the maxilla at the lower margin of the anterior nasal opening.
PNS Posterior nasal spine – the posterior spine of the palatine bone constituting the hard palate.
Ba Basion – the lowestpoint on the anterior rim of the foramen magnum.
• Frankfort plane
• Occlusal plane
• Palatal plane
• Mandibular plane
• SN plane
Analysis of facial skeleton
Analysis of jaw base.
Analysis of Dento-Alveolar relationship.
SADDLE ANGLE:
ARTICULAR ANGLE:
GONIAL ANGLE:
FACIAL HEIGHT:
EXTENT OF ANTERIOR AND POSTERIOR CRANIAL BASE LENGTH:
Analysis of facial skeleton:
SADDLE ANGLE
• Angle formed by joining points N S and Ar.
• Saddle angle increases when the condyle and
mandible are posteriorly positioned w.r.t cranial
base and maxilla.
• Unless there is deviation in position of the
mandible compensated by the linear and angular
measurements like ramal length and articulare
angle.
• A non compensated saddle angle caused by
posterior positioning of the mandible is very
difficult to be influenced by functional appliance
therapy.
• Mean value is 123±6°
• 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°
• The angle formed by the tangents to the body of
the mandible and posterior border of the ramus .
• It not only gives the form of the mandible but also
gives informtion about the direction of growth of
the mandible.
• If the angle is small it signifies horizontal growth
pattern and is favourable condition for anterior
positioning of the mandible using an activator.
• If the angle is large it signifies vertical growth
pattern.
• Mean value is 128± 7°.
• 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°.
• 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°.
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.
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.
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.
It is taken from N to Se.
It is increased in horizontal growth pattern and
reduced in vertical growth pattern.
Mean value is 75mm.
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.
SNA
SNB
BASE PLANE ANGLE
INCLINATION ANGLE
EXTENT OF MAXILLARY BASE
EXTENT OF MANDIBULAR BASE
LENGTH OF ASCENDING RAMUS
• 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 81°.
• In cases of very large SNA,like in Class II Div
1, Activator therapy is contraindicated.
• SNB expresses the sagittal reltionship between the
anterior extent of the mandibular apical base and
anterior cranial base.
• It is large with a prognathic mandible and small
with a retrusive mandible.
• If SNB is small and mandible is retrognathic
functional appliance therapy is indicated.
• 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°.
S’
N’
• It is the angle formed by the perpendicular line
dropped from N- Se 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° .
EXTENT OF MANDIBULAR BASE
EXTENT OF THE MAXILLARY BASE
LENGTH OF ASCENDING RAMUS
• 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 3mm more than the anterior
facial height until 12 yrs and 3.5mm more after
12 yrs.
• 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.
• Mean value is 44mm.
• 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.
• Mean value is 46mm.
• UPPER INCISORS
• LOWER INCISORS
• POSITION OF THE 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 102° .
• A smaller angle indicates the incisors are lingually tipped which is advantageous for functional appliance treatment.
.
• 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 then u
have reposition 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° .
• 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.
Mean value Patient
value
Inference
ANALYSIS OF FACIAL
SKELETON
1) Saddle Angle 123° + 5° 125 Mandible is post.
positioned w.r.t
cranial base and
maxilla.
2) Articular Angle 143° + 6° 148°
3) Gonial Angle 128° + 7° 128° average growth
pattern.
4) Sum of posterior angles 394° 401° Vertical growth
pattern.
5) Jarabak ratio 62 – 65% 56.29% Vertical growth
pattern.
6) Anterior cranial base
length
75 mm 74mm average growth
pattern.
7) Posterior cranial base
length
32 – 35 mm 35mm Average growth
pattern.
PARAMETERS MEAN
VALUE
PATIENT
VALUE
INFERENCE
1)SNA 82 + 2° 85° Forwardly placed
maxilla w.r.t
cranial base.
2)SNB 80±2° 75° Backwardly
placed mandible
w.r.t cranial
base.
3) Base plane angle 25° 31 Vertical growth
pattern
4) Inclination angle 85° 88° Upward and
forward
inclination of the
maxillary base.
5) Extent of maxillary
base
44mm 48mm
6)Extent of mandibular
base
67mm Average growth
7)Length of ascending
ramus
46mm 46mm Average growth
PARAMETERS MEAN
VALUE
PATIENT
VALUE
INFERENCE
UPPER INCISORS 102° 104° Labially tipped
upper incisors
LOWER INCISORS 90° 102° Labially tipped lower
incisors
POSITION OF UPPER
INCISORS
2-4mm 20mm Proclined upper
incisors
POSITION OF LOWER
INCISORS
-2-2mm 10mm Proclined lower
incisors
