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.
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
1) Lateral Cephalogram
• Lateral view of skull
• X-ray beam perpendicular to the patient's sagittal plane
2) 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
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
12. TRACING EQUIPMENTS:
1. A lateral cephalogram, the usual dimensions of 8x10 inches.
2. Acetate matte tracing paper (0.003 inches thick, 8x10 inches).
3. A sharp 3H drawing pencil or a very fine felt-tipped pen.
4. Masking tape.
5. View box.
6. 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. 1. 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
1. Soft tissue landmark
2. Hard tissue landmark
1. Points/landmarks
2. Planes/line
a. Horizontal plane
b. 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.
a. 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. b. 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.
c. 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.
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.
25. 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
26. Vertical planes
A-Pog line –
Point A on maxilla to
pogonion on mandible.
Facial plane –
nasion to pogonion,
Facial axis –
ptm point to gnathion.
E plane / esthetic plane –
most anterior point of
soft tissue nose & chin.
Planes
27. • 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)
28. Skeletal Perimeters
1. Facial angle
2. Angle of convexity
3. A-B Plane angle
4. Y- axies
5. Mandibular plane angle
Dental Perimeters
1. Can’t of occlussion
2. Inter incisal angle
3. Incisal occusal plane angel
4. Incisal mandibular plane angle
5. Upper incisal to A-pog line
29. 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: 87.5o ( 82o - 95o)
Facial angle
30. Angle of convexity Nasion-point A to point A –
pogonion.
Average value: 0o ( -8.5o - 10o).
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
31. Point A – point B to nasion – pogonion
(facial plane).
Average value: -4.6o ( -9 to 0o)
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
32. Sella gnathion to F.H. plane.
Average value: 59o ( 53 to 66o)
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
33. • Intersection of mandibular
plane with F.H. Plane.
Average value:
21.9o ( 17 to 28o)
Significance:
• Increased angle suggestive
of vertical grower/ hyper
divergent growth pattern
Mandibular plane angle
34. Occlusal plane to F.H. plane
Average value:
9.3o ( 1.5o - 14o)
Significance:
Gives a measure of slope of
occlusal plane relative
to F.H. Plane.
Dental Parameters
Cant of occlusal plane
35. Angle between long axes of
upper and lower incisors.
Average value: 135.4o ( 130o -
150.5o)
significance:
• decreased in class I bimaxillary
protrusion & class II div I.
• Increased in class II div II.
Inter incisal angle
36. 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: 14.5o ( 3.5o - 20o)
Significance:
• An increase in this angle is suggestive
of increased lower incisor
proclination.
Incisor occlusal plane angle
37. This angle is formed by intersection of
the long axis of the lower incisor and the
mandibular plane.
Average value: 1.4o (-8.2o - 7o)
Significance:
• An increase in this angle is suggestive
of increased lower incisor
proclination.
Incisor mandibular plane angle
38. 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
39. 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.
40. Skeletal analysis
1. Relating the maxilla to the
skull
2. Relating the mandible to the
skull
3. Relationship of maxilla to
mandible
4. Occlusal plane angle
5. Mandibular plane angle
Dental analysis
1. Maxillary incisor position
2. Upper Incisor to NA
Linear
3. Mandibular incisor
position
4. Inter-incisor angle
5. Lower incisor to chin
Soft tissue analysis
1. S line
41. 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: 820.
42. 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: 800.
43. 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 0- class III skeletal
relationship.
44. 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 0.
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.
45. 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.
46. 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.
47. 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- 220 .
Significance:
Increased both angular measurement
proclined upper incisor as class II div 1
48. 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.
49. 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 0
Significance:
• Shows forward or backward positioning of
these teeth.
• lower incisor to N-B in degrees indicates
their axial inclination.
50. 4. LOWER INCISOR TO N-B (linear)
Linear distance between the labial surface of lower
central incisor & line joining Naion to point B
Normal value: 4mm
Significance:
• Measurement helps in assessing the lower incisor
inclination.
• Increased in this measurement indicate proclined
lower incisors.
51. 5. INTER-INCISAL ANGLE
The relative position of the upper incisor to
that of the lower incisor.
Mean value : 1300
Significance:
• Acute or less than 130 degree- proclined.
• Greater than 130 degree/more obtuse -
retroclined.
52. 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.
53. 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.
• Lips located behind this line - concave
profile.
• Orthodontic correction of teeth or jaws
are required to approximate lips to the S-
Line.
54. 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.
55. • 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
56. DESCRIPTION
Frankfort horizontal plane
The three angles formed are:
1. Frankfort-mandibular plane
(FMA). - 250
2. Lower incisor to mandibular
plane (IMPA).- 900
3. Lower incisor to FH plane
(FMIA). - 650
Tweed’s triangle formed by:
1. Frankfort horizontal plane
2. The mandibular plane
3. The long axis of lower incisor
57. The basis is the FMA angle, and the following can be derived
from the change in its value as:
1. 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.
58. 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.
59. 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.
60. Effect of position of Nasion
A) Normal relationship
B) Nasion forward due to
long cranial base.
C) Nasion retropositioned
due to short cranial base.
61. Effect of angulation of jaws, occlusal
plane on ANB angle
A) Normal relationship.
B) Effect of counterclockwise
rotation of face .
C) Effect of clockwise
rotation of face.
62. • 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
63. 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.
64. 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.
65. 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.
66. Cephalometric superimposition
• Involves analysis of lateral cephalogram of same patient taken
at different time intervals.
• Helps to evaluate patient growth pattern, changes produced
by orthodontic & surgical procedures.
67. Cephalometric superimposition involve
1. Changes to the overall face.
2. Changes to the maxilla & maxillary dentition.
3. Changes to mandible and mandibular dentition
4. Amount and direction of condylar growth
5. Mandibular rotation.
68. 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
69. Broadbent triangle (1931)
• Triangle is obtained using nasion
(N), sella (s) & Boltons 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.
70. 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
71. Basion horizontal
• By Coben 1986.
• Constructed at the level of
anterior border of foramen
magnum parallel to FH
plane.
• Basion used as registration
point.
72. 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.
73. Maxillary superimpositions
• Used to determined the movement of maxillary
teeth in relation to the basal part of maxilla.
Method include:
1. Superimposition along the palatal Plane using
anterior nasal spine (ANS) as reference point.
2. Superimposition at the nasal floor & registered at
the anterior surface Of the maxilla.
3. Superimposition along the palatal plane using
pterygomaxillary fissure as the registration point.
4. Superimposition on best fit of internal palatal
surface.
5. Superimposition on the outline of infratemporal
fossa & posterior portion of hard palate
74. Mandibular superimposition
• Used to determined the movement of mandibular
teeth in relation to the basal part of mandible.
Superimposition includes:
1. Lower border of mandible
2. Constructed mandibular plane between menton
and gonion.
3. Anterior contour of chin
4. Anterior contour of cortical plates at the inferior
border of symphysis.
5. Contours of mandibular canal posteriorly & lower
contours of mineralized molar tooth germs.
