Cephalometrics

Types of cephalogram, uses of cephalogram, technical aspects, cephaometric- soft tissue, hard tissue & PA landmark, lines and panes in cephalometrics, Analysis- Downs, Steiner,Tweed. Wits appraisal, computerized cephalometric system, errors in cephalometry, cephalometric superimposition.

1. Cephalometrics in Orthodontics Dr. Shweta Kolhe BDS, MDS(Orthodontist)

2. The Assessment of cranio -facial structure forms a part of orthodontic diagnosis. Earliest method – artistic standards, harmony, symmetry and beauty. Now, using standardized skull radiograph – facial, dental and skeletal relationships as well as airway analysis Introduction

3. Roentgen 1895 – Discover X-ray. Paccini 1922 – standerdized radiographic head images at 2meterfrom X-ray tube. Boardbent 1931 USA & Hofrath in Germany – standerdizzed cephalometric technique. History

4. CEPHLO means head , METRIC means measurement. Cephalometric Analysis - a collection of data intended to compress as much of information from the cephalogram into a usable form for diagnosis, treatment planning and/or assessment of treatment effects. According to Moyer , cephalometrics is a radiographic technique for abstracting the human head into a geometric shape . DEFINITION

5. Types of cephalograms Lateral Cephalogram Lateral view of skull X-ray beam perpendicular to the patient's sagittal plane Frontal Cephalogram Anteroposterior view of skull X -ray beam perpendicular to the patient’s coronal plane

6. Uses of cephalograms In orthodontic diagnosis and treatment planning . Assesment of horizontal/vertical skeletal relationship, incisor position/inclination, soft tissue profile Orthognathic surgery Helps in classification of skeletal and dental abnormalities. Helps in evaluation of treatment results . Post-functional to assess skeletal/dental relationship Plan retention and monitor post retention phase Helps in predicting growth related changes . Research purpose

7. Technical Aspects Collimated X-ray source - 5 feet from mid-sagittal plane of patient Cephalostat - head positioner(with 2 ear rods and forehead clamp ) Aluminium wedge/ Barium paste - increases soft tissue definition Film - placed 1.5-1.8 foot behind mid-sagittal plane of patient with rare earth metal intensifying screen

8. Cephalostat Ear rods Forehead clamp

9. Positioning of the patient Frankfurt Horizontal plane should be parallel to floor. Ear rods stabilize the patient on the horizontal plane. Forehead clamp should be fixed for vertical plane stabilization of patient. Patient is made to close the mouth in centric occlusion.

10. Evaluation of Cephalometric Radiograph Digitizing Specialized software used to produce tracing Hand Tracing Carried out in a darkened room with (X-ray viewer) Acetate sheets used as transparency facilitates landmark identification and secured using masking tape Sharp pencil used ( 0.3mm leaded propelling pencil) Bilateral landmarks , unless directly super imposed, an average of two should be taken

11. Cephalometry Tracing Hand tracing D igital tracing

12. TRACING EQUIPMENTS : A lateral cephalogram , the usual dimensions of 8x10 inches. Acetate matte tracing paper ( 0.003 inches thick, 8x10 inches). A sharp 3H drawing pencil or a very fine felt-tipped pen. Masking tape. View box. A protractor.

13. A landmark is a point serving as a guide for measurement. An ideal landmark is located reliably on the skull and behaves consistently during growth. The reliability (reproducibility, dependability) of a landmark is affected by: 1. The quality of the cephalogram 2. The experience of the tracer 3. Confusion with other anatomic shadows. The validity (correctness or use as proof) of the landmark is determined largely by the way the landmark is used. Cephalometric Landmarks

14. Cephalometric landmarks and measure points should have the following attributes 1 . Landmarks should be easily seen, uniform in outline, easily reproducible. 2. Lines and planes should have significant relationship to the vectors of growth of specific areas of the skull. 3. Landmark should permit valid measurements of lines and angles projected. 4. Measurements should be amenable to statistical analyses .

15. Anatomic landmarks – actual anatomic structure. 2. Implants 3. Derived landmarks –obtained secondarily from anatomic structure. a. External points b. Intersections of edges of regression c. Intersections of constructed lines POINTS AND LANDMARKS—CLASSIFIED Soft tissue landmark Hard tissue landmark Points/landmarks Planes/line Horizontal plane Vertical plane

16. Implants are artificially inserted radio-opaque markers. They are "private points" and their position can vary. They may be located more precisely than traditional points and provide precise super positioning Ideal for longitudinal studies on the same subject. Anatomic "points" are really small regions, Each point has its own scale and its own uncertainty in one or two dimensions. Examples - the anterior nasal spine (ANS). Infradentale ( ID) and Nasion (Na). TRUE ANATOMIC POINTS IMPLANTS

17. Derived or created for the purpose of comparison or calculations of the cephalograms . These are of the following three types . External Points These points are extremes of curvature, e.g. incision superius (Is) Points whose coordinates are largest or smallest of all points on a specific outline, (e.g. "A point", "B Point". Gnathion ( Gn ), or Condylion (Co ) These points have less precision of location than true anatomic points . Derived Points

18. Intersection of Edges of Regression as "Points" "Points" defined as the intersection of images For instance, articulare ( Ar ) and - Pterygomaxillary fissure (PTM) Such "points" exist only in projections and are dependent on subject positioning . Intersection of Constructed Lines Intersection of constructed lines are used as points. e.g . Gonion sometimes is defined as the intersection of the ramal and mandibular lines.

19. Landmarks and planes Nasion Orbitale Porion Sella Point A Point B Basion Anterior Nasal Spine Posterior Nasal Spine Gonion Condylion Articulare Pogonion Menton Gnathion Ptm point Bolton Point

20. Landmarks

21. SOFT TISSUE PROFILE Glabella Nasion soft tissue Pronasale Subnasale Labrale superius Superior labial sulcus Stomion superius Stomion inferius Stomion Labrale inferius Pogonion soft tissue Menton soft tissue

22. SOFT TISSUE PROFILE G (glabella) - Most prominent point in the midsagittal plane of forehead ILS (inferior labial sulcus) - Point of greatest concavity in the midline of the lower lip Li ( labrale inferius )- Median point in the lower margin of lower membranous lip Ls ( labrale superius )- Median point in the upper margin of the upper membranous lip Ms ( menton soft tissue)- Constructed point of intersection of a vertical coordinate from menton and the inferior soft tissue contour of the chin Ns ( nasion soft tissue )- Point of deepest concavity of the soft tissue contour of the root of the nose Pn ( pronasale )- Most prominent point on the nose Pos ( pogonion soft tissue)- Most prominent point on the soft tissue contour of the chin Sls (superior labial sulcus)- Point of greatest concavity in the midline of upper lip Sn ( subnasale )- Point where the lower border of the nose meets the outer contour of upper lip St ( stomion )- Midpoint between stomion superioris and stomion inferius Sti ( stomion inferius )- Highest point on lower lip Sts ( stomion superioris )- Lowest point on upper lip.

23. POSTEROANTERIOR CEPHALOMETRIC LANDMARKS Antegonion ( ag ) Anterior nasal spine ( ans ) Condylar (cd) Coronoid ( cor ) Incision inferior frontale ( iif ) Incision superior frontale ( isf ) Lateral piriform aperture ( lpa ) Mandibular midpoint (m) Maxillary molar (um) Mandibular molar (lm) Mastoid (ma) Maxillare (mx) Medio - Orbitale ( mo ) Mental foramen (mf) Pont zygomatic arch ( za ) Zygomaticofrontal medial suture point in ( mzmf ) Zygomaticofrontal lateral suture point out ( lzmf )

24. Horizontal planes S.N . Plane – sella to nasion . F.H . Plane – orbitale to porion . Occlusal Plane – bisecting posterior occlusion of M & PM Palatal plane – ANS to PNS of palatine bone . Mandibular plane – gonion to gnathion . Basion-nasion plane / Cranial base Bolton’s plane- Bolton pt & nasion Lines & Planes Bo

25. Vertical planes A- Pog line – Point A on maxilla to pogonion on mandible. Facial plane – nasion to pogonion , F acial axis – ptm point to gnathion . E plane / esthetic plane – most anterior point of soft tissue nose & chin. Planes

26. Downs was derived from 20 Caucasian. 12 to 17 years with an equal number of boys and girls. Dental casts, models, photographs, cephalometric and intraoral radographs were taken of each . All individuals possessed clinically excellent occlusion . Consist of 10 parameter – 5 skeletal and 5 dental. According to Downs, “Balance of face is determined by position of mandible.” Frankfurt Horizontal plane used as reference plan to degree of retrognathism or prognathism . DOWN'S ANALYSIS (1948)

27. Skeletal Perimeters Facial angle Angle of convexity A-B Plane angle Y- axies Mandibular plane angle Dental Perimeters Can’t of occlussion Inter incisal angle Incisal occusal plane angel Incisal mandibular plane angle Upper incisal to A- pog line

28. Significance: Indication of antero - posterior positioning of mandible in relation to upper face. Increased in skeletal class III with prominent chin. Decreased in skeletal class II. Inside Inferior angle formed by intersection of nasion-pogonion plane and F.H. plane. Average value: 87.5 o ( 82 o - 95 o ) Facial angle

29. Angle of convexity Nasion -point A to point A – pogonion . Average value : 0 o ( -8.5 o - 10 o ). Significance : Revels convexity and concavity of skeletal profile Positive angle suggest a prominent maxillary dental base in relation to mandible. Convexity or Negative angle is indicative of prognathic profile

30. Point A – point B to nasion – pogonion (facial plane). Average value: -4.6 o ( -9 to o ) Significance : Indicative of maxillo mandibular relationship in relation to facial plane . Negative since point B is positioned behind point A. Positive in class III malocclusion or class I malocclusion with mandible prominence A-B plane angle

31. Sella gnathion to F.H. plane . Average value: 59 o ( 53 to 66 o ) Significance: Indicates growth pattern of a individual Increased in Class II facial patterns – Vertical growth pattern of mandible Decreased in Class III facial patterns – Horizontal growth pattern of mandible Y-Axis

32. Intersection of mandibular plane with F.H. Plane . Average value: 21.9 o ( 17 to 28 o ) Significance: Increased angle suggestive of vertical grower/ hyper divergent growth pattern Mandibular plane angle

33. Occlusal plane to F.H. plane Average value: 9.3 o ( 1.5 o - 14 o ) Significance: Gives a measure of slope of occlusal plane relative to F.H. Plane . Dental Parameters Cant of occlusal plane

34. Angle between long axes of upper and lower incisors. Average value: 135.4 o ( 130 o - 150.5 o ) significance: decreased in class I bimaxillary protrusion & class II div I. Increased in class II div II. Inter incisal angle

35. Inside inferior angle formed by the intersection between the long axis of lower central incisor and the occlusal plane read as a plus or minus deviation from a right angle Average value: 14.5 o ( 3.5 o - 20 o ) Significance: An increase in this angle is suggestive of increased lower incisor proclination . Incisor occlusal plane angle

36. This angle is formed by intersection of the long axis of the lower incisor and the mandibular plane. Average value: 1.4 o (-8.2 o - 7 o ) Significance: An increase in this angle is suggestive of increased lower incisor proclination . Incisor mandibular plane angle

37. linear measurement between the incisal edge of the maxillary central incisor and the line joining point A to pogonion . Average value: 2.7 mm(-1 - 5 mm ) Significance: The measurement is more in patients presenting with upper incisor proclination . Upper incisor to A- pog line

38. STEINER ANALYSIS (1930) Cecil C. Steiner evolved a composite analysis Anlysis provide the maximum information with least number of measurements. Steiner divided his analysis into three parts- 1. Skeletal 2. Dental 3. Soft tissues.

39. Skeletal analysis Relating the maxilla to the skull Relating the mandible to the skull Relationship of maxilla to mandible Occlusal plane angle Mandibular plane angle Dental analysis Maxillary incisor position Upper Incisor to NA Linear Mandibular incisor position Inter-incisor angle Lower incisor to chin Soft tissue analysis S line

40. 1. RELATING THE MAXILLA TO THE SKULL Significance: Angular reading is more than 82 degrees, protrusion of maxilla. Angular reading is less than 82 degrees, backward or retruded position of maxilla SNA angle - the lines S-N and N-point A. Mean value : 82 .

41. 2. RELATING THE MANDIBLE TO THE SKULL Significance: Angular reading is more than 80 degrees, protrusion of mandible. Angular reading is less than 80 degrees, backward or retruded position of mandible. SNB angle - the lines S-N and N-point B. Mean value : 80 .

42. 3. RELATIONSHIP OF MAXILLA TO MANDIBLE ANB angle - provides a general idea of the anteroposterior discrepancy of the maxillary to the mandibular apical bases. Mean value : 2 degrees. Significance: Angle greater than 2 0- - class II skeletal tendency . Angles less than 2 - class III skeletal relationship .

43. 4. OCCLUSAL PLANE ANGLE The occlusal plane - overlapping cusps of the first premolars and first molars. The occlusal plane to S-N plane is measured . Mean value: 14 . Significance: The angle is increased in long face or vertically growing and skeletal overbite cases . Decreased in horizontal growers or cases with skeletal deep bite .

44. 5. MANDIBULAR PLANE ANGLE S-N plane & mandibular plane (Go- Gn ). Mean Value- 32 degrees . Significance: Excessively high or low mandibular plane angles suggest unfavorable growth patterns and these are likely to affect treatment results .

45. THE DENTAL ANALYSIS This part of the analysis is designed to confirm the clinical observations already made and to determine the position of the dentition with respect to their respective bony bases and to each other.

46. 1. MAXILLARY INCISOR POSITION The maxillary incisor (intersection of long axis of central incisors) is related to the N-A plane by angular measurements. Inclination/angular relationship of U1 Normal value- 22 . Significance: Increased both angular measurement proclined upper incisor as class II div 1

47. 2. Upper Incisor to NA Linear Linear measurement between the labial surface of upper incisor and the line joining Nasion to Pt A. Normal value : 4mm Significance: Increased with increased proclination .

48. 3. MANDIBULAR INCISOR POSITION The relative antero -posterior angulation of the lower incisor teeth is determined Most protruding incisor to the N-B line Normal value: 25 Significance: Shows forward or backward positioning of these teeth. lower incisor to N-B in degrees indicates their axial inclination.

49. 4 . LOWER INCISOR TO N-B (linear) L inear distance between the labial surface of lower central incisor & line joining N aion to point B Normal value: 4mm Significance: Measurement helps in assessing the lower incisor inclination. Increased in this measurement indicate proclined lower incisors.

50. 5 . INTER-INCISAL ANGLE The relative position of the upper incisor to that of the lower incisor. Mean value : 130 Significance: Acute or less than 130 degree- proclined . Greater than 130 degree/more obtuse - retroclined .

51. THE SOFT TISSUE ANALYSIS The analysis laid emphasis on the soft tissue profile as well as the underlying skeletal infrastructure. The profile is mainly affected by the chin, nose and the lips . The shape and the posture of the lips is partially governed by the underlying dentition and thus can be modified orthodontic ally.

52. STEINER’S S-LINE According to steiner , the lips in balanced faces , should touch a line extending from the soft tissue contour of the chin to the middle of an S formed by the lower border of the nose. This line is referred to as the S-line. Significance: Lips located beyond this line -protrusive. L ips located behind this line - concave profile. Orthodontic correction of teeth or jaws are required to approximate lips to the S-Line.

53. TWEED ANALYSIS Aid to treatment planning, anchorage preparation and determining the prognosis of orthodontic cases. This analysis is based primarily on the deflection of the mandibular plane angle (FMA) and the posture of the lower incisor.

54. To determine the final position of lower incisors should occupy at the end of treatment so space requirement is calculated and decision regarding extraction is made. As an aid in treatment planning and anchorage preparation. Determining the prognosis of orthodontically treated cases. Objectives

55. DESCRIPTION Frankfort horizontal plane The mandibular plane long axis of lower incisor The three angles formed are: Frankfort-mandibular plane (FMA ). - 25 Lower incisor to mandibular plane (IMPA ).- 90 Lower incisor to FH plane (FMIA ). - 65 Tweed’s triangle formed by: Frankfort horizontal plane The mandibular plane The long axis of lower incisor

56. The basis is the FMA angle, and the following can be derived from the change in its value as: FMA 16 to 28: good prognosis ( 60 percent of malocclusions) at 16, IMPA should be 95 at 22, IMPA should be 90 at 28, IMPA should be 85 2. FMA from 28 to 35 : prognosis fair at 28, IMPA should be 85 extactions necessary majority of cases at 35, IMPA should be 80 to 85. 3. FMA above 35, prognosis bad, extractions frequently complicate problems. Tweeds stressed the importance of the FMIA angle, recommending that it be maintained at 65 to 70.

57. WITS APPRAISAL Wits appraisal is not analysis is diagnostic aids to easure AP relation. Alexander Jacobson was the head of orthodontic department at university of Witwatersrand Johannesburg, South Africa that’s why name “wits” There are many situations in which ANB reading cannot be relied upon e.g. position of Nasion , rotation of jaw.

58. Applications of wits appraisal The ANB angle is shown to be affected by several enviornmental factors , diagnosis based on this angle may give false results , in certain cases . Factors affecting ANB angle- 1) Patient’s age- ANB has a definite tendency to reduce with increasing age . 2) Change in spatial position of nasion . 3) Rotational effect of jaws 4) Change in the angle SN to occlusal plane . 5) The degree of facial prognathism .

59. Effect of position of Nasion Normal relationship Nasion forward due to long cranial base. Nasion retropositioned due to short cranial base.

60. Effect of angulation of jaws, occlusal plane on ANB angle Normal relationship. Effect of counterclockwise rotation of face . Effect of clockwise rotation of face.

61. Occlusal plane is drawn through the region of overlapping cusps of premolars & molars. Perpendiculars are drawn on occlusal plane from points A & B. Contact points labelled as AO & BO. WITS APPRAISAL

62. Clinical Significance – In skeletal class II,BO located well behind AO. In skeletal class III,BO would be forward of point AO. Greater the wits reading – Greater the jaw discrepancy.

63. Computerized cephalometic systems Computers are widely used in cephaometrics . Allow quick digitizing landmark & generate analysis. Superimposition of serial radiograph possible. Easy storage and retrieval of cephalometric tracing & value. Combination of cephalometric data with other patient records & photographs.

64. Errors In Cephalometry Radiographic projection errors – Magnification & distortion of image. Errors within measuring system – human error. Errors in landmark identification - quality of radiograph, precision of landmark identification & reproducibility, operator bias.

65. Cephalometric superimposition Involves analysis of lateral cephalogram o f same patient taken at different time intervals. Helps to evaluate patient growth pattern, changes produced by orthodontic & surgical procedures.

66. Cephalometric superimposition involve Changes to the overall face. Changes to the maxilla & maxillary dentition. Changes to mandible and mandibular dentition Amount and direction of condylar growth Mandibular rotation.

67. Superimposition technique Done by superimposing serial film on a stable registration point that chges little during the growth period. Broadbent triangle Sella - Nasion line Basion horizontal Basion – nasion plane Maxilary superimposition Mandibular suprimposition

68. Broadbent triangle (1931) Triangle is obtained using nasion (N), sella (s) & B oltons point (Bo). R point is midpoint of perpendicuar from the center of sella to Bolton plane. Serial tracing is done on R point keeping BO-Na plane parallel to each other.

69. Sella - Nasion line Method was described by American Board of orthodontics 1990 Tracings are oriented on the sella - nasion plane using sella as registration point

70. Basion horizontal By Coben 1986. Constructed at the level of anterior border of foramen magnum parallel to FH plane. Basion used as registration point.

71. Basion – Nasion Plane By Ricketts in 1979. Tracing is superimposed on Basion – Nasion plane point CC used as registration point. CC point is the intersection of the basion – nasion plane and facial axis.

72. Maxillary superimpositions Used to determined the movement of maxillary teeth in relation to the basal part of maxilla. Method include: Superimposition along the palatal Plane using anterior nasal spine (ANS) as reference point. Superimposition at the nasal floor & registered at the anterior surface Of the maxilla. Superimposition along the palatal plane using pterygomaxillary fissure as the registration point. Superimposition on best fit of internal palatal surface. Superimposition on the outline of infratemporal fossa & posterior portion of hard palate

73. Mandibular superimposition Used to determined the movement of mandibular teeth in relation to the basal part of mandible. Superimposition includes: Lower border of mandible Constructed mandibular plane between menton and gonion . Anterior contour of chin Anterior contour of cortical plates at the inferior border of symphysis . Contours of mandibular canal posteriorly & lower contours of mineralized molar tooth germs.

74. Thank You