2. A. History of cephalometrics
B. Uses of cephalograms
C. Types of cephalograms
D. Cephalometric landmarks and planes
E. Cephalometric tracing technique
F. Tissue analysis:
i. Downs’ analysis
ii. Steiners analysis
iii. Ricketts analysis
G. Conclusion
H. References
CONTENTS
3. HISTORY
The first truly scientific attempt at cranial measurements was done by SPIGEL in 16th
century by publishing “ LINAE CEPHALOMETRICAE”
He mentioned
facial
occipital
frontal
sincipital lines
Wilhelm Conrad Roentgen invented X-Rays in 1895, which revolutionised the
diagnostic medicine.
The measurement of the head from the shadows of bony and soft tissue landmarks on the
radiographic image became known as “Roentgenographic cephalometry”
4. 1ST Introduced cephalogram to
orthodontics.
VAN
LOON
1ST identified Nasion, Sella,
Pogonion,Gonion,ANS.
A J
PACINI
1st to give method of obtaining
profile radiograph.
SIMPSON
HOLLY BROADBENT
Redefined cranio-stat and
standardized cephlometric
technique
6. WHY CEPHALOGRAM?
• An accurate appraisal of jaw relationship, can only be determined radiographically and not
dental cast alone.
• Degree of incisor inclination cannot be ascertained from plaster casts.
• Vertical jaw discrepancies can be ascertained from cephalogram.
• For proper diagnosis and treatment planning. Eg – in differential diagnosis in Class II and
Class III.
• For study of growth and maturation.
9. CEPHALOMETRIC LANDMARKS
A conspicuous point on a cephalogram that
serves as a guide for measurement or
construction of planes – Jacobson
ANATOMIC LANDMARK -
TWO TYPES
ANATOMIC CONSTRUCTED
Are really small regions which
might be located on solid skull
even better than cephalogram.
Eg – ANS ,Na,Point A , Point B
,etc
Obtained secondarily from anatomic
structures in the cephalogram.
Eg- Gn,Go,Se, Point A revisted,Xi
point
10. REQUISITES FOR A LANDMARK
Should be easily seen on the roentgenogram
Be uniform in outline
Easily reproducible
Should permit valid quantitative measurement of lines and angles
Lines and planes should have significant relationship to the vectors of
growth
33. TRACING TECHNIQUE
Tracing supplies & equipments
Lateral ceph, usual dimensions of 8 x 10
inches (patients with facial asymmetry requires
antero posterior head film)
Acetate matte tracing paper (0.003 inches
thick, 8 X 10 inches)
A sharp 3H drawing pencil or a very fine felt-
tipped pen
34. •Masking tape
•A few sheets of cardboard (preferably black), measuring approximately 6 x 12
inches, and a hollow cardboard tube
• A protractor and tooth-symbol tracing template for drawing the teeth (optional)
• Dental casts trimmed to maximal intercuspation of the teeth in occlusion
• Viewbox (variable rheostat desirable, but not essential)
• Pencil sharpener and an eraser
36. Section 2 : Cranial base, internal border of cranium, frontal
sinus, ear rods
internal border of
cranium
Trace orbital roofs
Sella turcica
Planum sphenoidale
Bilaterally present
frontal sinuses
Dorsum sella
Superior, midline of
occipital bone
Floor of middle cranial
fossa
Ear rods
Section 2 : Cranial base, internal border of cranium, frontal sinus, ear rods
37. Section 3 : Maxilla & related structures including nasal bone &
pterygomaxillary fissures
nasal bone
Thin nasal maxillary bone surrounding
piriform aperture
Lateral orbital margins
Bilateral key ridges
Bilateral pterygomaxillary fissures
ANS
Superior outline of nasal floor
PNS
Anterior outline of maxilla
Outline of maxillary incisors
Maxillary first molars
38. Anterior border, symphysis
Marrow space of symphysis
Inferior border of mandible
Posterior aspect of rami
Mandibular condyles
Mandibular notches & coronoid
process
Anterior aspect of rami
Mandibular first molars
Mandibular incisors
Section 4 : The mandible
40. Cephalometric planes
Used for measurements, separation of anatomic divisions, definition of
anatomic structures of relating parts of the face to one another.
HORIZONTAL VERTICAL
1. Frankfurt Horizontal Plane
2. Sella Nasion Plane
3. Basion Nasion Plane
4. Palatal Plane
5. Occlusal Plane
6. Mandibular Plane
1. Facial Plane
2. A-Pog Plane
3. Facial Axis
4. E Plane (esthetic plane)
43. Mandibular plane: Several mandibular planes are used in cephalometries, based on
the analysis being done. The most commonly used ones are:
1. Tangent to the lower borer of the mandible (Tweed).
2. A line connecting gonion and gnathion (Steiner).
3. A line connecting gonion and menton (Downs).
60. DOWNS ANALYSIS
Down's in 1948
Reason for formulating this analysis: Racial profile could be retrusive or protrusive yet
be harmonious in proportions.
Sample: 20 subjects compromising of only Caucasian subjects.
Age group of 12 to 17 years
Equal number of boys and girls
61. He deduced that there are four types of faces as viewed on lateral profile:
1. Retrognathic with a recessive lower jaw
2. Mesognathic with an ideal or average lower jaw
3. Prognathic with a protrusive lower jaw
4. True prognathism with a pronounced protrusion of the lower face.
66. • Angle increased in case of prominent chin.
• Angle decreased in case of a retruded chin.
67. ANGLE OF CONVEXITY
• Formed by the intersection of the line
from Nasion to Point A and Point A to
pogonion.
Range: -8.5° to 10°
Mean: 0°
68. Positive angle suggests prominence of the
maxillary teeth relative to the mandible.
Negative angle is associated with a
prognathic profile.
69. A B PLANE ANGLE
A-B plane angle is a measure of the
relation of the apical bases of the
maxilla and mandible to each other
relative to the facial line.
RANGE : 0 TO -9 degree
MEAN : -4.6 degree
70. point B is usually behind point A, this angle is usually negative.
Positive angle is seen in case of Class III or in cases of mandibular
prominence.
A large negative value is indicative of a Class II pattern.
71. MANDIBULAR PLANE ANGLE
• RANGE : 17 – 28 degree
• MEAN : 21.9 degree
• High mandibular plane angles are
suggestive of unfavourable
hyperdivergent facial pattern.
72. Y – AXIS
• Range: 53 to 66°
• Mean: 59.4°
• This angle is greater in
Class II tendencies than
in Class III tendencies.
73. • A decrease in the y-axis in serial radiographs can be taken
to be an indication of greater horizontal than vertical facial
pattern.
• An increase in the y axis is suggestive of vertical growth
exceeding horizontal growth of the mandible.
74. CANT OF OCCLUSAL PLANE
• The cant of occlusal plane is
a measure of the slope of the
occlusal plane to the Frankfort
Horizontal plane.
• Range: 1.5 to 14°
• Mean: 9.3°
75. INTERINCISAL ANGLE
• In cases where the
incisors are tipped forward
on the denture base, the
angle is seen to be small.
• Range: 130-150°
• Mean: 135.4°
76. • The inferior inside angle is read as a
positive or negative deviation from a
right angle.
• The positive angle increases as the
teeth incline forwards.
• Range: 3.5 to 20°
• Mean: 14.5°
INCISOR OCCLUSION PLANE ANGLE
77. INCISOR – MANDIBULAR PLANE ANGLE
• Range: -8.5° to 7°
• Mean: 1.4°
• This angle is positive
when the incisors are
tipped forward on the
denture base.
80. THE POLYGON
• The polygon / wiggle.
• Developed by Vorhies
and Adams (1951)
• It is a graphical
representation of large
group of cephalometric
readings.
81. Drawbacks of Down’s Analysis :
Sample size is very small
Studies conducted by Sheldon Baurind in 1971, using "Scattergrams"
considerable variations ….. Frankfort Horizontal plane i.e. the porion and orbitale.
Errors of interpretations should be avoided ….in cases of unusual locations
E.g., Nasion in small orbitale cavities or when anomalies lie in the temporal bone.
It is difficult to locate porion as it is a variable point,
always advisable to use …. true ear hole (locate a point at the top of the external auditory
meatus)
82. Location of the occlusal plane …. bisects the overlapping cusp of the 1st molars and the incisal overbite
grossly malpositioned teeth & in cases of crowding ….. Difficult
85. SNA ANGLE
• It indicated the relative
anteroposterior
positioning of the maxilla
to the cranial base.
• Mean: 82°
86.
87. SNB ANGLE
• Mean: 80°
• If the angle is greater than
80°: protrusive mandible
• If the angle is less than 80° :
retrusive mandible.
SNB ANGLE
• Mean: 80°
• If the angle is greater than 80°:
protrusive mandible
• If the angle is less than 80° :
retrusive mandible.
88. ANB ANGLE
• Mandible to maxilla
• Mean: 2°
• Reading greater than 2° : class
II tendency
• Reading less than 2°: class III
tendency
89. OCCLUSAL PLANE ANGLE
• Mean: 14°
• Gives an indication of the
growth pattern of an
individual
90. MANDIBULAR PLANE ANGLE
• Mean: 32°
• Excessively high or low
mandibular angles are
indicative of unfavourable
growth patterns.
91. MAXILLARY INCISOR POSITION
• Whereas the linear measurement of
the same, provides the relative
forward or backward positioning of the
incisor teeth to the N-A line.
• Mean: 4mm
92.
93. MANDIBULAR INCISOR POSITION
• Linear measurement –
relative forward or
backward positioning of
teeth
• Angle – relative axial
inclination.
• Mean:
Linear- 4mm
Angle : 25°
94. INTER INCISAL ANGLE
• Mean: 130°
• If the angle is less than 130° -
indicative of need for uprighting of
maxillary incisors, mandibular incisors
or both.
• If the angle is greater than 130° - the
incisors often require advancing
anteriorly (as in the case of class II div
1)
95. LOWER INCISOR TO CHIN
• Ideally according to Holdaway, the
distance between labial surface of
lower incisor to NB line should be
equal to chin prominence (i.e 4mm)
• 2mm discrepancy – acceptable
• 3mm – less desirable
• >4mm – corrective measures indicated
96. SOFT TISSUE ANALYSIS
• Steiner gave a soft tissue line –
“S line” for determining soft
tissue facial balance.
• Lips extending beyond the S –
line - protrusive
• Lips falling short of this line –
retrusive
97. Drawbacks of Steiner’s Analysis :
The reference plane (S-N plane) ….. discrepancies due to the points constructing the plane.
Although nasion bears anatomic significance to the face,
sella - housing for the hypophysis of the brain and the pituitary gland,
totally unrelated to the face / the jaws in particular.
However, it bears little significance to the mandible and its morphology.
98. The nasion point, …may deviate from its mid sagital plane due to asymmetry of the nasal bones.
variations cannot be detected in the radiographs …relative broadening of the image at the nasion point
The mean values of the SNA angles …. male and female samples agree quite closely but the variance are
consistently significantly greater for females.
The significance of angle ANB varies according to the size of the angle SNA
99. The point A … varies invariably
(outline of the alveolar bone extending from the central incisor composing the inferior aspect which is
usually not very clearly visible in the radiograph)
The anterior nasal spine …. can affect the vertical and anteroposterior location of point A and its
variation reflect heavily on the location of point A.
The point B - varies considerably in its vertical relationship
determination in relation to the mandibular border places the point more in the region of the apices.
100. Shortcomings of ANB Angle :
Taylor, C.M., 1969. Changes in the relationship of nasion, point A and point B and the effect upon ANB. Am J Orthod., 56: 143-63
101. RICKETTS ANALYSIS
Ricketts produced his analysis in 1960s
Sample: 1000 people
Female- 546
Male-454
Mean age -8.9yrs
107. Planes:
Facial axis (Pt to Gn)
Condylar axis (DC to Xi)
Corpus axis (Xi to PM)
108. PARAMETERS
• These landmark points, planes and axis are used to describe the face in
terms of depth, height, width, and bony profile contour.
1. Locate the chin in face
2. Locate the maxilla through the convexity of face
3. Locate the denture in the face
4. Evaluate the profile
109. CHIN IN SPACE
1. Facial axis
2. Facial (depth) angle
3. Mandibular plane angle
CONVEXITY
4. Convexity of point A
TEETH
5. Lower incisor to A-Pog
6. Upper molar to PtV
7. Lower incisor to A-Pog inclination
Parameters
110. Facial axis:
The angle formed between the basion-nasion plane
and the plane from foramen rotundum (PT) to
gnathion.
Mean: 90⁰ ± 3.5⁰
< 90° : Retro-positioned chin
> 90° : Protrusive / Forward growing chin
111. Facial (depth) angle:
• The angle between the facial plane (N-Pog) and the FH.
• Mean: 87⁰ ± 3⁰ (Adjust +1⁰ every 3 years)
• Changes with growth
• Indicates the horizontal position of the chin &
• Suggests whether a Class II / Class III pattern due to the
position of the mandible.
112. Mandibular plane:
• The angle between the mandibular plane and the FH.
• Mean: 26⁰ ± 4.5⁰ (Adjust -1⁰ every 3 years)
• High / Steep MP angle: Open bite
• Low MP angle: Deep bite
113. CONVEXITY
Convexity at point A:
• The convexity of the middle face is measured from point A to
the facial plane (N-Pog).
• Mean: 2 mm ± 2 mm (Adjust -1 degreeevery 5 years)
• High convexity: Class II skeletal pattern( convex profile)
• -ve convexity: Class III skeletal pattern(concave profile)
114. TEETH
Lower incisor to A- Pog:
• A-Pog plane / Dental plane – Refence line to
measure the position of anterior teeth.
• Idealy mandibular incisors should be positioned
1mm ahead of A-Pog line.
• Mean: +1 mm
• Used to define the protrusion of the lower arch.
115. Upper molar to PtV:
• The distance from the pterygoid vertical (back of the maxilla) to
the distal of the upper molar
• Mean: Age + 3 mm
• Assists in determining whether the malocclusion is due the
position of upper & lower molar.
• Useful in deciding whether extractions are necessary.
116. Lower incisor inclinations (l to A-PO):
• The angle between the long axis of the lower
incisor and the A-PO plane (l to A-PO)
• Mean: 22⁰ ± 4⁰
• It provides idea of lower incisor procumbency.
117. PROFILE
LOWER LIP TO E-LINE
• Distance between lower lip and E-line
• Indication of soft tissue balance between lip and
the profile
• Lower lip is 2mm behind and Upper lip is 4 mm
behind
118. CLINICAL RELAVANCE OF E LINE
A patient with significant crowding of both upper and lower arches. The clinician must
decide whether to consider extracting teeth, such as first premolars or expanding the
arch
• If the lips in profile were on or in front of the “E” plane, the decision would be
extraction and anterior retraction, improving the lip to “E” plane relationship.
• If on the other hand the lower lip is 6 mm behind the “E” plane, the decision would
be to align the teeth and expand the arch, moving the anterior teeth and lips to a
more anterior and prominent position
119. Shortcomings of Rickett’s Analysis:
It is not consider the position & the inclination of maxillary incisors.
It does not clearly define the sagittal maxillomandibular relationship.
Anteroposterior position of the jaws is not given much importance as the
vertical relationship.
120. CONCLUSION
There are numerable cephalometric analysis given by different people each expressing
their ideas and ways to analyse, classify, and treat the face
All these analysis are still a two dimensional representation of the three dimensional
structure. Each has inherent deficiencies associated with the analysis itself and those
because of radiological errors and clinician’s experience
The future of cephalometrics depends on the three dimensional analysis, their accuracy,
validity and reproducibility. Still the value of the information and insight given by these
traditional analyses should not be ignored or taken lightly
121. REFERENCES
McNamara, J A Jr: A method of Cephalometric evaluation. AJO 1984, Dec Vol 86 pg 449- 469
William Proffit: Contemporary Orthodontics 3rd Edition, 2000pg 179- 181
Athanasio E Athanasiou: Orthodontic Cephalometry, 1995 pg 269
A Jacobson, PW Caufield: Introduction to Radiographic Cephalometry, 1988
The Wits appraisal of jaw disharmony. Alexander Jacobson. AJODO-2003 Volume 124, Number-5
Wylie. L Windell. The assessement of anterioposterior dysplasia. Angle Ortho 1947 17-109
122. Thomas G M, Valiathan A: A Cephalometric comparison of South Indian and North Indian population using six
analysis. Dissertation submitted to mangalore university, June 1993
Bhat M, Sudha P, Tandon S: Cephalometric norms for Bunt and Brahmin children of Dakshina Kannada based on
McNamara’s analysis. J Indian Soc Pedo Prev Dent ,June 2001 pg 41- 51
Johnston LE Jr: An objective evaluation of the pitchfork analysis (PFA), EJO 2002 vol 24 page 121- 123
R Mannchen: A critical evaluation of the pitch fork analysis , EJO 2001 vol 23 pg 1- 14
CDJ Rushforth, PH Gordon, JC Arid: Skeletal and Dental changes following the use of Frenkel Functional
Regulator , BJO June 1999 pg 127- 134
Johnston LE Jr :Balancing the Books on Orthodontic Treatment: An integrated Analysis of Change, BJO 1996 pg
93- 102
Editor's Notes
The most anterior point of the frontonasal suture in the median plane
This is the tip of the bony anterior nasal spine in the medial plane. It corresponds to the anthropometrical point acanthion.
The intersection of a continuation of the anterior wall of the pterygopalatine fossa and the floor of the nose marking the dorsal surface of the maxilla
The point at the deepest midline concavity between the two central on the maxilla midway between the anterior nasal spine and prosthion (Downs 1948)
The lowest and most anterior point on the alveolar portion of the premaxilla. in the median plane. between the upper central incisors
The lowest point in the inferior margin of the orbit, midpoint between right and left images (Arne Bjork 1947)
The height of curvature of bone overlying the frontal sinus
The most anteroinfeior point on the tips of the nasal bones as seen from norma lateralis (Spiro J Chaconas 1969)
This is the point representing the midpoint of the pituitory fossa (sella turcica). It is a constructed point in the median plane.
midpoint of the line connecting the posterior clinoid process and the anterior opening of the sella turcica. It is independent of depth of the sella (Schwartz).
A bilateral teardrop-shaped area of radiolucency the anterior shadow of which represents the posterior surfaces of the tuberosities of the maxilla (Robert E Moyers 1978).
intersection of the inferior border of the foramen rotundum with the posterior wall of the pterygomaxillary fissure. Usually 110clock position istaken as point ptm.
The median point of the anterior margin of the foramen magnum
can be located by following the image of the slope of the anterior border of the basilar part of the occipital bone to its posteiror limit (Coben).
The highest point in upward curvature of the retrocondylar fossa (Broadbent 1931). i.e.. the highest point at the post condylar notch of the occipital bone.
The highest bony point on the upper margin of external auditory meatus.
The highest and most anterior point on the alveolar process in the median plane between the mandibular central incisors.
The point at the deepest midline concavity on the mandibular symphysis between infradentale and pogonion (Downs 1948).
most anterior point of the bony chin in the median plane.
most antero-inferior point on the symphysis of the chin. It is constructed by intersecting a line drawn perpendicular to the line connecting menton and pogonion.
The most inferior midline point on the mandibular symphysis.
The constructed point of intersection of the ramus plane and the mandibular plane.
The point of intersection of the images of the posterior border of the condylar process of the mandible and the inferior border of the basilar part of the occipital bone (redefined by Coben after Bjork).
Hence a wide variation can be expected between different races and people.
it may not be very well applicable to the adults, as age changes can be also be expected.
sella and the nasion are both situated in the interiors of the skull and cannot be visualized clinically and therefore cannot be utilized as a tool for actual direct clinical communications.
it has been suggested that for every one degree that SNA falls below the standard value half a degree should be substracted from the ANB of 3° and half a degree should be added to every degree of increase.
CF: point of intersection of pterygoid root vertical to FH
Functional occlusal plane
Also varies with position of pogonion
Helps to find out the overjet is due to malpositioning of upper or lower incisors or both
