Rakosis analysis

RAKOSIS ANALYSIS

Dr sooraj s pillai 1st Yr PG.

INTRODUCTION:

The Rakosis analysis is an important diagnostic tool in planning functional appliance therapy.

REFERENCE POINTS USED IN RAKOSIS ANALYSIS

N Nasion - most anterior point of the frontonasal suture 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.

REFERENCE PLANES USED IN RAKOSIS ANALYSIS.

• Frankfort plane• Occlusal plane• Palatal plane• Mandibular plane• SN plane

THE RAKOSIS ANALYSIS CAN BE DIVIDED INTO 3 DIVISIONS:

Analysis of facial skeleton

Analysis of jaw base.

Analysis of Dento-Alveolar relationship. 

ANALYSIS OF FACIAL SKELETON

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°

ARTICULAR 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°

GONIAL ANGLE

• 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°.

UPPER AND LOWER GONIAL ANGLE 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°.

• 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:

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.

FACIAL HEIGHT

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.

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.

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.

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.

ANALYSIS OF JAW BASES

SNA SNB BASE PLANE ANGLE INCLINATION ANGLE EXTENT OF MAXILLARY BASE EXTENT OF MANDIBULAR BASE LENGTH OF ASCENDING RAMUS

SNA

• 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

• 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.

BASE PLANE ANGLE: (PAL – MP)

• 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’

INCLINATION ANGLE

• 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° .

LINEAR MEASUREMENT OF THE JAW BASES

EXTENT OF MANDIBULAR BASE

 EXTENT OF THE MAXILLARY BASE

LENGTH OF ASCENDING RAMUS

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 3mm more than the anterior facial height until 12 yrs and 3.5mm more after 12 yrs.

EXTENT OF THE 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.

• Mean value is 44mm.

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.

• Mean value is 46mm.

ANALYSIS OF DENTOAVEOLAR RELATIONSHIP

• UPPER INCISORS

• LOWER INCISORS

• POSITION OF THE INCISORS

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 102° .• A smaller angle indicates the incisors are

lingually tipped which is advantageous for functional appliance treatment.

.

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 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 UPPER INCISOR:

POSITION OF THE LOWER INCISOR:

• 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.

RAKOSIS ANALYSISMean 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.

ANALYSIS OF JAWBANALYSIS OF JAW BASESASES

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

ANALYSIS OF DENTOALVEOLAR RELATIONSHIP

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

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