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Postero anterior cephalometric analysis /certified fixed orthodontic courses by Indian dental academy

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Postero anterior cephalometric analysis /certified fixed orthodontic courses by Indian dental academy

  3. 3. INTRODUCTION Malocclusions and dentofacial deformities constitute three-dimensional conditions or pathologies. Orthodontic patients requires comprehensive three- dimensional diagnostic examination. The assessment of postero-anterior and basilar cephalometric views are particularly important for dento- alveolar and facial asymmetries; dental and skeletal crossbites and functional mandibular displacements
  4. 4. A postero anterior cephalogram can be analysed so that the vertical, transverse, and sagittal dimensions can be evaluated .Vertical asymmetry can be observed readily in a postero anterior cephalogram by connecting bilateral structures or landmarks, by drawing the transverse planes, and by observing their relative orientation
  7. 7. RICKETT’S ANALYSIS  Given by:Robert M. Ricketts., Ruel W. Bench, James J. Hilgers,and Robert Schulhof in1972  The frontal & lateral films should be correlated together to evaluate the patient three- dimensionally.  According to them, in order to provide a better method of communication, a new classification system for each parameter was devised.  The normal value represented by the mean & the amount of variation around that mean was established which was acceptable from a clinical point of view :
  8. 8.  Nasal cavity width - measured from NC to NC  Mandibular width - measured Ag to Ag (at eminence above notch);
  9. 9.  Maxillary width - two frontal lines, left and right, are constructed from the medial margins of the zygomaticofrontal sutures to Ag points,and the maxillarv width is evaluated on left and right sides separately by relating J point or point jugale (defined as the crossing of the outline of the tuberosity with that of the jugal process) to these lines. In this way the maxillary width is evaluated in relation to the mandible;
  10. 10.  Symmetry - a midsagittal plane is constructed by dropping a line through the top of the nasal septum or crista galli, perpendicular to the line connecting the centres of the zygomatic arches.  Asymmetry is evaluated by relating point ANS and pogonion to this midsagittal plane;
  11. 11.  Intermolar width - measured from the buccal surface of the first permanent molars transversely;  Intercuspid width - the width between the tips of the lower cuspids;
  12. 12.  Denture symmetry - the midpoints of the upper and lower central incisor roots are related to the midsagittal plane;  Upper to lower molar relation - the differences in width between the upper and lower molars.  The measurement is made at the most prominent buccal contour of each tooth.
  13. 13.  FIELD I :The denture problem (Occlusal Relation) Factor Measured value (mm) Clinical norm (mm) Clinical deviations from norm Molar relation Left 0 1.5 -1.0 Molar relation Right -0.5 1.5 -1.3 Intermolar width 54.8 54.5 .2 Intercanine width 22.7 23.9 -0.4 Denture midline .5 0 .3
  14. 14.  FIELD II:The Skeletal problem (Maxillo-Mandibular Relation) Factor Measured value Clinical norm Clinical deviations from norm Max-Mand width Left -10.7 mm -10.8 mm .0 Max-Mand width right -11.4 mm -10.8 mm -0.2 Max-Mand midline .7 deg 0 deg .3
  15. 15.  FIELD III: Denture to Skeleton Factor Measured value (mm) Clinical norm (mm) Clinical deviations from norm Molar to Jaw Left 5.6 6.2 -0.3 Molar to Jaw Right 6.2 6.2 -0.0 Denture Jaw midline .5 0 .3 Occlusal Plane Tilt -0.7 0 -0.4
  16. 16.  FIELD V: The Determination Problem (Craniofacial Relation) Factor Measured value Clinical norm Clinical deviations from norm Postural Symmetry 1.1 deg 0 deg .5
  17. 17.  FIELD VI: The Internal Structure Problem (Deep Structure) Factor Measured value Clinical norm Clinical deviations from norm Nasal Width 24.6 mm 24.9 mm -0.2 Nasal Proportion 53.7 deg 59.0 deg -1.2 Maxilla Proportion 99.6 deg 103.1 deg -0.7 Mandible Proportion 87.2 deg 88.6 deg -0.4 Facial Proportion 95.1 deg 97.5 deg -0.8
  18. 18. HEWITT ANALYSIS  Given by:A.B.Hewitt in 1975  The facial complex consists of numerous constituent parts it is therefore the degree of harmony between the parts which determines the symmetry of the whole.  This study was devised to establish a method for the analysis of overall facial symmetry in terms of its component, each of which is capable of individual variations between the right and left sides.
  19. 19. Method:  63 cephalometric PA radiograph of normal children  Age range: 9 to 18 years with a mean of 14 years.  20 males, 43 females.  No child with a degree of clinically evident or unacceptable facial asymmetry or gross deviation of dental occlusion was included.  Facial disharmony may be expressed as variation in shape or of size.  Deviations in the shape of the face may be assist by determining the angle of divergence of two facial axis that is the anatomical axis of the middle and lower third of the
  20. 20.
  21. 21.  A line was drawn between the following points to form an axis X which represents the middle third of the face: 1. Sella 2.Bisector of line joining the medial extent of orbits. 3.Bisector of line joining the right and left orbitale.
  22. 22. 4. Bisector of line joining the right and left mastoidale. 5. Anterior nasal spine. 6. Bisector of line joining bilateral zygomatic points. 7. Bisector of lines joining right and left molar points.
  23. 23.  The following points were joined by a line to form an axis N which represents the lower third of the face: 1. Bisector of line joining condylar points. 2. Menton. 3. Bisector of line joining bilateral gonial points.
  24. 24.  The angle of divergence of the axes is proportional to the degree of asymmetry between the middle and lower third of the face.  The angle between the two axis can be bisected to give the arbitary anatomical axis of the face.  In order to assist the relative asymmetry of the component areas of the facial complex, a method of triangulation was used.
  25. 25.  Triangles are drawn on both sides of the tracing: 1. Triangle A: between the extreme superior extent of the head of condyle, exteme mesial extent of the head of the condyle and sella to represent the cranial base region. 2. Triangle B: between sella, mastoidale and the root of zygoma representing the lateral maxillary regions.
  26. 26. 3. Triangle C: joining sella, anterior nasal spine and the root of zygoma representing the upper maxillary region. 4.Triangle D: drawn between the root of the zygoma, upper molar points and the anterior nasal spine representing the right and left middle maxillary region.
  27. 27. 5. Triangle E: joining ANS, upper molar points and the point of intersection of a line drawn between the bilateral upper molar points and the arbitary anatomical axis representing the right and left lower maxillary region.
  28. 28. 6.Triangle F: drawn between upper molar points, upper incisal points and the point of intersection of a line joining the upper molar points and the anatomical axis, representing the right and left dental regions. 7.Triangle G: drawn between the condylar points, gonion and menton to represent the mandibular component of the face.
  29. 29.  Conclusion: He concluded that the cranial base regions and the maxillary regions exhibit an overall asymmetry with a larger side being the left where as the mandibular and dentoalveolar regions exhibit a greater degree of symmetry.
  30. 30. SVANHOLT & SOLOW ANALYSIS  Given by: SVANHOLT.P & SOLOW.B in 1977  Aim: To analyse one aspect of transverse craniofacial development, namely the relationships between the midlines of the jaws and the dental arches
  31. 31.  Lo- latero orbitale- the intersection of the lateral orbital contour with the innominate line  ORP- orientation plane  Om- orbital midpoint- the projection on the line lo-lo of the top of the nasal septum at the base of the crista galli
  32. 32.  Mx- maxillare- the intersection of the lateral contour of the maxillary alveolar process and the lower contour of the maxillozygomatic process of the maxilla  M- mandibular midpoint- located by projecting the mental spine on the lower mandibular border, perpendicular to the line Ag-Ag
  33. 33.  CPL-compensation line  MXP-maxillary plane  Iif- incision inferior frontale- the midpoint between the mandibular central incisors at the level of the incisal edges
  34. 34.  MLP-mandibular plane  Isf- incision superior frontale- the midpoint between the maxillary central incisors at the level of incisal edges
  35. 35. 1. Transverse maxillary position - mx-om/ORP; 2. Transverse mandibular position - m-om/ORP; 3. Transverse jaw relationship - CPL/MXP;
  36. 36. 4. Upper incisal position - isf-mx/MXP; 5. Lower incisal position — iif-m/MLP; 6. Upper incisal compensation - isf- mx/m; 7. Lower incisal compensation - iif-m/mx.
  37. 37.  Dentoalveolar compensations will move the midpoint of the dental arch away from the symmetry line within one jaw towards the compensation line CPL.  If the dental arch midpoint reaches the compensation line, the compensation is complete.  If the midpoint of the dental arch does not reach the compensation line,there is incomplete dentoalveolar compensation.  Displacements of the midpoints of the dental arch in a direction opposite to the direction from the jaw symmetry line to the compensation line are called Dysplastic
  38. 38. GRAYSON ANALYSIS  Given by:Barry H. Grayson,, Joseph G. McCarthy,, and Fred Bookstein in 1983  It’s a three-dimensional, multiplane cephalometric analysis  This analysis permits the visualization of skeletal midlines at selected depths of the craniofacial complex.  This localizes craniofacial asymmetry in the posteroanterior and basilar views.
  39. 39.  Three separate acetate tracings are made on the same radiograph, corresponding to structures of the lateral view in or near the three planes
  40. 40.  A- orbital rims are outlined  B- pyriform aperture  C-maxillary and mandibular incisors  D- midpoint of the symphysis.  This represents the anatomy of the most superficial aspects of the face as transected by line A First tracing
  41. 41.  A- greater and lesser wings of the sphenoid  B- most lateral cross section of the zygomatic arch  C-coronoid process  D- maxillary and mandibular first permanent molars Second tracing
  42. 42.  E- body of the mandible  F- mental foramina .  These structures, all located on or near plane B , represent a deeper coronal plane. Second tracing
  43. 43.  A- upper surface of the petrous portion of the temporal bone  B- mandibular condyles with the outer border of the ramus down to the gonial angle  C- mastoid processes with the arch of temporal and parietal bones connecting them . Third tracing
  44. 44.  In the A plane (the pyriform aperture, orbits, and incisors), the centrum of each orbit is located , and the point Mce halfway between them is identified.  The most lateral point on the perimeter of each pyriform aperture is marked, and the point Mp halfway between them is marked.
  45. 45.  The midpoint Mi, between the maxillary and the mandibular central incisors, and the gnathion Mg are identified.  To view the midline , straight lines are constructed connecting Mce with Mp, Mp with Mi, and Mi with Mg. This results in a segmented construct whose angles express the asymmetry of the structures of this plane.
  46. 46.  A midline is constructed for the B plane (the sphenoid, zygomatic arch etc.).  Intersection of the shadows of the greater and lesser wings of the sphenoid, are identified, and their bisector Msi is recorded  Midpoints Mz for the centre of the zygomatic arches
  47. 47.  Mc for the tips of the coronoid processes  Mx for maxillare on the left and right zygomas  Mf for the left and right mental foramina.  Vertical line segments are constructed to link these points
  48. 48.  In plane C  Md- heads of the condyles  Mm-innermost inferior points on the mastoid processes  Mgo- gonions  This yield bisecting points  Segments Md – Mm, Mm – Mgo
  49. 49.  If the midline constructs of A, B, and C planes are superimposed on the posteroanterior tracing, one can observe a phenomenon we call warping within the craniofacial skeleton  The midline constructs deviate progressively laterally as one passes from plane C, through plane B, to plane A toward the anterior of the face to the P-A composite.
  50. 50.  Three horizontal planes of the face were drawn  In the basilar-view planes, key triangles are constructed A, B, and C, each of which may be referred to this primary (posterior) midsagittal plane.
  51. 51.
  52. 52.  Superpositioning of the triangles clearly demonstrated the warping of the craniofacial complex  The craniofacial skeleton is most severely deviated from the midsagittal plane at the level of the mandible; the severity of asymmetry decreased in a cephalic direction.
  53. 53. The study of structures in various coronal and transverse planes makes it possible to measure and record the three-dimensional relationship of anatomic structures to one another.
  54. 54.  Given by: Chierici G in 1983 This method focuses on the examination of the asymmetry in the upper face  A line connecting the lateral extent of the zygomaticofrontal sutures on each side (line zmf-zmf) is constructed  Line X is drawn through the root of the crista galli perpendicular to zmf-zmf Line line X
  55. 55.  Examination of the different structures & landmarks on both right & left sides on the same plane & the deviation of the midline structures can identify asymmetry
  56. 56. GRUMMON’S ANALYSIS  Given by:Duane C. Grummons, & Martin A. Kappeyne Van De Coppello in 1987  Since the advent of cephalometric radiography, orthodontists have focused on the lateral x-ray as their primary source of patient skeletal and dentoalveolar data.  However, the frontal (PA) and basilar views also contain valuable information for diagnosis and treatment planning procedures.  Various dental and skeletal widths and skeletal asymmetries that are not available from the lateral cephalogram can be quantified from a frontal radiograph
  57. 57.  Such frontal and asymmetry information is vitally important in: 1. Orthodontic surgery planning 2. Differential tooth eruption with segmental TMJ splint therapy 3. Functional jaw orthopedics including three dimensional improvements in facial or dental proportions or symmetry. Limitations of Previous Analyses:  Angular measurements and ratios are absent from previous frontal analyses.  Nor do they measure mandibular morphology, which can be seen clinically to play the major role in asymmetries.
  58. 58.  A new PA analysis has been developed to provide clinically relevant information about specific locations and amounts of facial asymmetry.  There are two forms of this Grummons analysis— Comprehensive frontal asymmetry analysis Summary frontal asymmetry analysis  Parameters : 1. Horizontal planes 2. Mandibular morphology 3. Volumetric comparison 4. Maxillomandibular comparison of asymmetry 5. Linear asymmetry assesment 6. Maxillomandibular relation 7. Frontal vertical proportions
  59. 59.
  60. 60.  Four planes are drawn to show the degree of parallelism and symmetry of the facial structures  First plane connect the medial aspects of the zygomatic frontal sutures (Z-Z)
  61. 61.  Second plane connects the centers of the zygomatic arches (ZA)  Third plane connects the medial aspects of the jugal processes (J).  Fourth plane is drawn at menton parallel to the Z plane.
  62. 62.  MSR has been selected as a key reference line because it closely follows the visual plane formed by subnasale and the midpoints between the eyes and eyebrows. MSR
  63. 63.  MSR normally runs vertically from Cg through ANS to the chin area, and nearly perpendicular to the Z plane.  The relation of MSR to the center of the cervical vertebrae can alert the clinician to possible head rotation when the PA headfilm was taken.
  64. 64.  Construction of MSR may have to be modified if the patient has anatomic variations  If the location of Cg is in question, an alternative method of drawing MSR is to draw a line from the midpoint of the Z plane through ANS.  If there is upper facial asymmetry, MSR can be drawn as a line from the midpoint of the Z plane through the midpoint of an Fr-Fr line.
  65. 65.  Left and right triangles are formed from the heads of the condylar processes or the condyles (Co),the antegonial notches (Ag), and menton. These are split by the ANS-Me line and compared  ANS-Me parallels the visual dividing line from subnasale to soft tissue menton in the lower face.
  66. 66.  Two "volumes" (polygons) are calculated from the area defined by each Co-Ag- Me and the intersection with a perpendicular from Co to MSR  Superimposition of both the polygons done to know the asymmetry
  67. 67.  Perpendiculars are drawn to MSR from J and Ag, and connecting lines from Cg to J and Ag  This produces two pairs of triangles, each pair bisected by MSR.  If perfect symmetry is present, the four triangles become two, J-Cg-J and Ag-Cg-Ag.
  68. 68.  The vertical offset as well as the linear distance is measured from MSR to Co, NC, J, Ag, and Me  Difference between the left and right values will indicate asymmetry
  69. 69.  To allow tracing of the functional posterior occlusal plane, an .014" wire is placed across the mesio-occlusal areas of the maxillary first molars.  The wire should extend about 3mm buccally to make it easy to recognize on the headfilm
  70. 70.  Distances are measured from the buccal cusps of the upper first molars (on the occlusal plane) along the J perpendiculars.
  71. 71.  The Ag plane, MSR, and the ANS-Me plane are also drawn to depict the dental compensations for any skeletal asymmetries in the horizontal or vertical planes (maxillomandibular imbalance)
  72. 72.  Midline asymmetries of the upper and lower incisors and Me-MSR are also provided
  73. 73.  Skeletal and dental measurements are made along the Cg-Me line with divisions at ANS, A1, and B1 . The following ratios are calculated 1. Upper facial ratio— Cg- ANS/Cg-Me 2. Lower facial ratio— ANS-Me/Cg-Me 3. Maxillary ratio— ANS- A1/ANS-Me
  74. 74. 4. Total maxillary ratio— ANS-A1/Cg-Me 5. Mandibular ratio— B1- Me/ANS-Me 6. Total mandibular ratio— B1-Me/Cg-Me 7. Maxillo-mandibular ratio— ANS-A1/B1-Me
  75. 75.  The comprehensive fontal asymmetry analysis consists of all the data described & three tracings.  The horizontal planes, mandibular morphology, and maxillo-mandibular comparisons have been combined to produce the Summary Facial Asymmetry Analysis  Conclusion: They concluded that head rotation and improper construction of MSR can reduce the effectiveness of this analysis  This analysis is intended to provide a practical, functional method of determining the locations and amounts of facial asymmetry. It is of greatest clinical value when integrated with data from lateral and submental vertex radiograph.
  76. 76. Many articles & analyses have been published on normative data related to the facial structures that have been studied by means of lateral cephalograms. However, publications describing the use of posteroanterior cephalometric radiography are relatively few. In recent years there has been a growing demand for extended roentgenocephalometric control material as a result of the refinements in syndrome identification & the advances in the treatment of craniofacial anomalies All the existing cephalometric data are of value for the diagnosis of various types of craniofacial anomalies & for monitoring growth of persons or groups of corresponding age & race.
  77. 77. BIBLIOGRAPHY  Athanasios E Athanasiou and Aart JW Van der Meij: Orthodontic Cephalometry , Mosby-Wolfe Publications,1997 ,3rd edn. , 162-172.  Robert M. Ricketts, Rue W. Bench, James J. Hilgers, Robert Schulhof, An overview of Computerized Cephalometrics. Am J Orthod 61:1-28  Grummons Dc, Kappeyne van de Coppello MA. A Frontal asymmetry analysis. J Clin Orthod 21:448-65  Grayson BH, McCarthy JG, Bookstein F. Analysis of craniofacial asymmetry by multiplane cephalometry. Am J Orthod 84: 217-24  Hewitt Ab. A Radiographic study of facial asymmetry . Br J Orthod 21: 37-40