cephalometric landmarks

1. Made By: JUBIN BABU
4th YEAR BDS
Guided By: Dr. HITEN KALRA
Dr. PRAFFUL KUMAR

2. HISTORY OF CEPHALOMETRIC RADIOGRAPHY
o In 1895, Prof. Wilhelm Conrad Roentgen made a
remarkable contribution to science with the
discovery of x-rays

3. o On December 28, 1895 he submitted a paper “On A New Kind
of Rays, A Preliminary Communication” to the Wurzburg
Physical Medical Society.
o Prof. Wilhem Koening & Dr. Otto Walkhoff simultaneously
made the first dental radiograph in 1896.
o It was clear that the use of x-rays provided the means of
obtaining a different perspective on the arrangement and
relation of bones thus expanding the horizons of craniometry
& cephalometry .

4. o In 1922 Paccini standardized radiogrpahic head images by
positioningthe subjects against a film cassette at a distance of 2
meters from the X-ray tube.
o In 1931 Boardbent in USA and Hofrath in Germany
simultaneously presented a standardized cephalometric
technique using a high powered X-ray machine and a head
holder called cephalostat.
o The term CEPHALOMETRICS is used to describe the analysis
and measurements made on the cephalometric radiographs.

5. TECHNICAL ASPECTS
o The patient’s head was centred in the cephalostat with
the superior borders of the external auditory meatus
resting on the upper parts the two ear rods.
o The lowest point on the inferior bony border of the left
orbit, indicated by the orbital marker, was at the level of
the upper parts of the ear rods.
o Nose clamp was fixed at the root of the nose to support
the upper face.

6. o The focus film distance was set at 5 feet (152.4 cm)
and the subject film distance could be measured to
calculate image magnification.
o With the two X ray tubes at right angles to each
other in the same horizontal plane, two images
(lateral & PA) could be simultaneously produced.

7. CEPHALOGRAM CAN BE OF TWO TYPES:
a) LATERAL CEPHALOGRAM: this provides a
lateral view of the skull. It is taken with the
head in a standardized reproducible
position at a specified distance from the
source of the X ray.
b) FRONTAL CEPHALOGRAM: this provides an
antero-posterior view of the skull.

10. CEPHALOMETRIC LANDMARKS
o Cephalometric landmarks are readily recognizable
points on a cephalometric radiograph or tracing,
representing certain hard or soft tissue anatomical
structures (anatomical landmarks) & (derived
landmarks).
o Anatomic landmarks represent actual anatomic
structures of the skull.
o Derived landmarks are the landmarks obtained
secondarily from anatomic structures in the
cephalogram.

11. REQUIREMENTS
o Should be easily seen on the roentgenogram,
o Be uniform in out line, and easily reproducible.
o Should have significant relationship to the vectors of
growth.
o Should permit valid quantitative measurements of
lines and angles projected from them.
o Measurements should be amenable to statistical
analyses.

14. LATERAL CEPHALOMETRIC LANDMARKS
Nasion (N,Na) : the most anterior on the frontonasal sutures
in the midsagittal plane
Orbitale (Or) : the lowest point on the inferior margin of the
orbit.
Porion (Po): the most superior point on the outline of the
external auditory meatus (anatomic). The superior most
point of the ear rods (machine porion) sometimes is used.

16. Gonion (Go): the most posterior inferior point on the
outline of the angle of the mandible.
Pogonion(pog): its is the most anterior point of the
boney cin in the median plane.
Gnathion (Gn) : the most anterior inferior point on the
bony chin in the midsagittal plane.
Menton (Me) : the most inferior point of the
mandibular symphysis in the midsagittal plane.

18. A-point (Point A, Subspinale, SS) : the most posterior
midline point on the concavity between the ANS
and prosthion.
Anterior nasal spine (ANS): the anterior tip of the
sharp bony process of maxilla at he lower margin
anterior nasal opening.

20. Articulare (Ar) a point at the junction of the posterior
border of ramus of mandible and inferior border of
posterior cranial base (occipital bone).
B-point (Point B, Supramentale, sm): the most
posterior midline point in the concavity of the
mandible between the most superior point on the
alveolar bone overlying the mandibular incisors
(infradental) and Pog.

22. Basion (Ba): the lowest point on the anterior rim of the
foramen magnum.
Bolton (Bo): the intersection of the outline of the
occipital condyle and the foramen magnum at the
highest point on the notch posterior to the occipital
condyle.

24. Pterygo-maxillary fissure (PTM) : bilateral inverted tear drop
shaped radiolucency whose anterior border represents
the posterior surfaces of the tuberosities of the maxilla.
Sella (S) : the geometric centre of the pituitary fossa (sella
turcica), determined by inspection – a constructed point
in the midsagittal plane.
Posterior nasal spine (PNS) : the most posterior point on the
bony hard palate in the midsagittal plane, the meeting
point between inferior & superior surfaces of the hard
palate at its posterior aspect.

26. POSTERO-ANTERIOR CEPHALOMETRIC
LANDMARKS
ag - antegonion - the highest point in the antegonia/ notch (left and right)
cd - condylar - the most superior point of the condylar head (left and right)
cor - coronoid — the most superior point of the coronoid process (left and
right)
iif- incision inferior frontale - the midpoint between the mandibular central
incisors at the level of the incisal edges
isf - incision superior frontale - the midpoint between the maxillary central
incisors at the level of the incisal edges
m - mandibular midpoint - located by projecting the mental spine on the
lower mandibular border, perpendicular to the line ag-ag

28. Ipa - lateral piriform aperture - the most lateral aspect of the
piriform aperture (left and right)
lo - latero-orbitale - the intersection of the lateral orbital contour
with the innominate line (left and right)
Im - mandibular molar - the most prominent lateral point on the
buccal surface of the second deciduous or first permanent
mandibular molar (left and right)
mo - medio-orbitale - the point on the medial orbital margin that
is closest to the median plane (left and right)
mf - mental foramen - the centre of the mental foramen (left and
right)

30. tns - top nasal septum - the highest point on the superior aspect
of the nasal septum
ma - mastoid - the lowest point of the mastoid process (left and
right)
mx - maxillare - the intersection of the lateral contour of the
maxillary alveolar process and the lower contour of the
maxillozygomatic process of the maxilla (left and right) . Aka
JUGAL POINT
um - maxillary molar - the most prominent lateral point on the
buccal surface of the second deciduous or first permanent
maxillary molar (left and right)