Mc namara analysis

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Mc namara analysis

  1. 1. AJEESHA NAIR
  2. 2. INTRODUCTION  Dr JAMES A McNAMARA  1984
  3. 3.  A method of cephalometric analysis that is sensitive not only to the position of the teeth within a given bone but also to the relationship of the jaw elements and cranial base structures one to another.  In short, the method of analysis described here represents an effort to relate teeth to teeth, teeth to jaws, each jaw to the other, and the jaws to the cranial base.
  4. 4. Skeletal and dental components of the face in normal occlusion
  5. 5. Maxillary skeletal protrusion
  6. 6. Maxillary dentoalveolar protrusion
  7. 7.  The method of analysis described here represents an effort to relate  teeth to teeth,  teeth to jaws,  each jaw to the other, and  the jaws to the cranial base.
  8. 8. THE COMPOSITE NORMATIVE STANDARDS DERIVED FROM 3 SAMPLES 1 2 3 • Lateral cephalograms of the children comprising the Bolton standards • Selected values from a group of untreated children from the Burlington Research Centre • A sample of 111young adults from Ann Arbor, having good to excellent facial and dental configurations and good skeletal balance with an orthognathic facial profile
  9. 9. Soft tissue evaluation NASOLABIAL ANGLE CANT OF UPPER LIP Hard tissue evaluation
  10. 10. DRAWING A LINE TANGENT TO THE BASE OF THE NOSE AND A LINE TANGENT TO THE UPPER LIP FORMS THE NASOLABIAL ANGLE
  11. 11. CANT OF UPPER LIP
  12. 12. Hard tissue evaluation NP FH .A Relationship of point A to nasion perpendicular
  13. 13. 0 mm in mixed dentition 1 mm in adult male& female
  14. 14.  In well – balanced faces,this measurement is: 0 mm in mixed dentition 1 mm in adult females and males.
  15. 15. Exceptions
  16. 16. MAXILLA TO MANDIBLE
  17. 17. Maxilla To Mandible Anteroposterior relationship Midfacial length Effective mandibular length Maxillomandibular differential Any effective midfacial length corresponds to an effective mandibular length .
  18. 18. MID-FACIAL LENGTH  measuring a line from Condylion to point A. Condylion- most posterosuperior point on the outline of mandibular condyle MANDIBULAR LENGTH  -measuring a line from Condylion to anatomic Gnathion Gnathion – most anteroinferior aspect of the mandibular symphysis.
  19. 19. Condylion Point A Gnathion
  20. 20.  The effective lengths of max & mand are related to the size of the component parts . Thus termed: small for mixed dentition medium for adult female large for adult male The Maxillomandibular Difference : In small individuals: 20-24 mm, In medium sized individuals: 25-28 mm In large individual : 29-33 mm
  21. 21. •A Gn
  22. 22. VERTICAL RELATIONSHIP LOWER ANTERIOR FACIAL HEIGHT MANDIBULAR PLANE ANGLE FACIAL AXIS ANGLE
  23. 23. measured from). anterior nasal spine(ANS) to Menton(Me Increases with age. If LAFH retrognathic mandible. Correlated to the effective length of the midface. If LAFH prognathic mandible
  24. 24.   It is the angle between anatomic FH and the line drawn along the lower border of the mandible through constructed Gonion(Go) and Menton(Me). Average is 22 ± 4 degrees.  - Excessive lower facial height  - Deficiency in lower facial height.
  25. 25.    It is formed by a line constructed from the posterosuperior aspect of the pterygomaxillary fissure (PTM) to gnathion(Gn) and a line perpendicular to cranial base (ie a line from basion(Ba) to nasion(N). An ideal relationship is when PTM-Gn lies on the perpendicular(0 degrees). If PTM-Gn lies anterior to the perpendicular, the angle is positive, suggesting deficient vertical development of face and vice versa.
  26. 26. MANDIBLE TO CRANIAL BASE
  27. 27.  Is determined by measuring distance from pogonion to nasion perpendicular.  In mixed dentition 6-8 mm (behind N per)  In adult female 0-4 mm (behind N per)  In adult male 2 mm(behind to 5 mm fwd of N per)
  28. 28. DENTITI0N Helps in determining the antero-posterior position of both upper and lower incisors
  29. 29. Ideal distance measured horizontally from point A to the facial surface of maxillary incisors is 4 to 6 mm
  30. 30.  Anteroposterior position: Measurement of the facial surface of the lower incisor to the A-Pogonion line. Normal = 1 - 3 mm
  31. 31. In vertical position mandibular incisors are related to functional occlusal plane.  If curve of Spee is excessive incisors intruded or molars Extruded LAFH is the determining factor 
  32. 32. AIRWAY ANALYSIS
  33. 33.  Two measurements are used to examine the possibility of airway impairment. Upper pharynx Lower pharynx
  34. 34. It is measured from a point on the posterior outline of the soft palate to the closest point on the posterior pharyngeal wall.  Normal(adults) - 17.4 mm  Increases with age
  35. 35. It is measured from the intersection of the posterior border of the tongue and the inferior border of the mandible to the closest point on the posterior pharyngeal wall.  Normal – 10 – 12mm  Does not change with age
  36. 36. SIGNIFICANCE  Adenoid obstruction of upper airway – upper pharyngeal width decreases.  Lower pharyngeal width –greater than 15 mm -anterior positioning of tongue – habitual or enlargement of tonsils .
  37. 37. McNamara Analysis 1. Maxilla to cranial base Normal Patient Inference Nasolabial Angle 102±8˚ 110˚ Normal upper lip Cant of upper lip 14±8˚ 8˚ Normal upper lip Point A to Nperpendicular 0-1mm -9mm retrusive maxilla
  38. 38. 2.Maxilla to mandible Normal Patient value Inference Maxillary Length 100.9 103mm Maxillary length normal Mandibular Length 131mm 127mm decreased mandibular length (136-139) Anteroposterior Maxillomandibula 30mm r differential 24mm decreased Vertical LAFH(ANS-Me) 71.6mm 67mm Reduced Mandibular Plane Angle(FH-Go-Me) 22± 4˚ 34˚ VGP Facial Axis Angle 0±3.5˚ -7˚ VGP
  39. 39. Normal Patient Value Inference 0-4mm -13mm Backwardly placed chin Maxillary incisor to point A 4-6mm 7mm Protrusive upper incisor Mandibular incisor to A-p0g 1-3mm 5mm Protrusive lower incisor 3.Mandible to cranial base Pog to Nperpendicular 4.Dentition 5.Airway Upper pharynx 15-20mm 17mm Normal upper pharyngeal width L0wer pharynx 11-14mm Normal lower pharyngeal width 12mm
  40. 40. References  Radiographic Cephalometry-Jacobson 2nd edition  AJO-DO 1984 Dec (449-469)-McNamara

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