Rakosi’s analysis

Rakosi’s analysis is an important diagnostic tool in planning functional appliance therapy.

1. RAKOSI’s ANALYSIS Prof . Maher Fouda By. Mohamed Al.khawlani Mansoura University Faculty of Dentistry Orthodontics Department Egypt

2. INTRODUCTION The Rakosi’s analysis is an important diagnostic tool in planning functional appliance therapy.

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.

29. ANALYSIS OF DENTOALVEOLAR RELATIONSHIP UPPER INCISORS LOWER INCISORS POSITIONS OF THE INCISORS

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.

33. Thank you for attention