Posterio anterior cephalometric analysis

POSTERIO-ANTERIOR
CEPHALOMETRIC ANALYSIS
By:
Dr Jasmine Arneja
Precepted by:
Dr Shalaj
Dr vishal

 Introduction
 Setup
 General landmarks
 MSR
 Ricketts analysis
 Grummons analysis
 Hewitts analysis
 Svanholt and Solow analysis
 Grayson analysis
 conclusion
Contents:

 In orthodontics, the primary indication for obtaining a
posteroanterior cephalometric film is the presence of
facial asymmetry.
 it is also important in cases of dentoalveolar
asymmetries, dental and skeletal crossbites, and
functional mandibular displacements. (transverse
discrepancies)
 The posteroanterior cephalometric projection, also
called as the Caldwell projection.
Introduction

 A headholder or a cephalostat that can be rotated
90° is used, so that the central X-ray beam penetrates
the skull of the patient in a posteroanterior direction
and bisects the transmeatal axis perpendicularly.
 The standard distance from X-ray source to patient is
5 feet (152.4 cm)
 The tip of the nose and forehead should lightly touch
the cassette and the FHP should be parallel to the
floor
Cephalometric set-up

 No double shadows
 The top of the petrous portion of the temporal bone
should lie near the center of the orbit
Sign of a good PA cephalogram

 Being a more reproducible position, NHP is now
frequently used. Natural head position is a
standardized orientation of the head, which is readily
assumed by focusing on a distant point at eye level
(Moorrees, 1985).
 Reproducibility of natural head position, assessed as
the error of a single observation, has been found to
be close to 2°, which supports its use in cephalometry
(Lundstrom and Lundstrom, 1992).

 ag - antegonion - the highest point in the
antegonia/ notch (left and right)
 ans — anterior nasal spine 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

 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)

 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)

 za - point zygomatic arch - point at the most
lateral border of the centre of the zygomatic
arch (left and right)
 mzmf - zygomatic ofrontal medial suture point-
in - point at the medial margin of the
zygomaticofrontal suture (left and right)
 Izmf - zygomaticofrontal lateral suture point-out
- point at the lateral margin of the
zygomaticofrontal suture (left and right)
 A1 point- point selected at the interdental
papilla of the upper incisors at the junction of
crown and gingiva
 B1 point- point selected at the interdental
papilla of the lower incisors at the junction of
crown and gingiva

 B1- most reliable skeletal landmark
 Mandibular canine- most reliable dental landmark
 Mandibular 6 and maxillary 3- least reliable dental
landmarks
 ZF suture- least reliable skeletal landmark
(Gravely JF, Benzies PM. The clinical significance of tracing error in cephalometry. Br
J Orthod 1974)
Most and least reliable landmarks

 The MSR normally runs vertically
from crista galli to the through the
anterior nasal spine to the chin
area and typically nearly
perpendicular to the Z plane
 If the location of Cg is in question:
midpoint of the Z plane an be
connected to the ANS
 If there is upper facial asymmetry,
midpoint of the Z plane can be
connected to the midpoint of the
Fr- Fr line
MEDIAN SAGGITAL REFERENCE
PLANCE in PA Ceph

 Most of the posteroanterior cephalomctric analyses described in the literature are
quantitative, and they evaluate the craniofacial skeleton by means of linear absolute
measurements of:
 width or height (Solow, 1966; Ricketts et al, 1972; Ingerslev and Solow, 1975; Movers
et al, 1988; Nakasima and Ichinose, 1984; Grummons and Kappeyne van de Coppello,
1987; Athanasiou et al, 1992);
 angles (Ricketts et al, 1972; Svanholt and Solow, 1977; Droschl, 1984; Grummons and
Kappeyne vande Coppello, 1987; Athanasiou et al, 1992);
 ratios (Costaras et al, 1982; Grummons and Kappeyne van de Coppello, 1987;
Athanasiou et al, 1992); and
 volumetric comparison (Grummons and Kappeyne van de Coppello, 1987).
 The different structures of the craniofacial complex can also be analysed using
qualitative methods (Sollar, 1947; Grayson et al, 1983; Proffit, 1991).
 The analysis proposed by Grummons and Kappeyne van de Coppello (1987) contains
quantitative assessment of vertical dimensions and proportions.
PA ceph analysis

 Ricketts gave a normative data of parameters
measured, which is helpful in determining the vertical
transverse skeletal and dental problems
 It has the following components:
 Dental realtions
 Skeletal relations
 Dental to skeletal
 Jaw to cranium
 Internal structures
RICKETTS ANALYSIS

Dental relations:
 Molar relations (a6-b6):
difference in width between
the upper and lower molars
measured at the most
prominent buccal contour of
each tooth. Used to describe
bucco-lingual relation of
molars

Dental relations:
 Intermolar width (b6-b6):
from buccal surface of
mandibular left to right
molar. Helpful in
determining the eitiology
of crossbite.

Dental relations:
 Intercanine width (b3-b3) : from tip
of mandibular right to left canine.
 Normal value: 22.7 mm at age 7 (non
erupted teeth). The distance widens
0.8 mm per year until age 13 when it
reaches the adult value of 27.5 mm
 Denture midline: midline of upper
arch to lower arch

Skeletal relations:
 Maxillomandibular width
right: from the Jugal
process to the frontofacial
plane (Ag to MZF- j). Useful
in determining the skeletal
crossbite.
 Maxillomandibular width
left

Skeletal relations:
 Maxillomandibular midline:
angle formed by the ANS-
Me plane to a plane
perpendicular to ZA-AZ
 Interpretation: Determines
the mandibular midline
deviation with respect to the
midsagittal plane. This
asymmetry might be the
consequence of functional
or skeletal problems

Skeletal relations:
 Maxillary width : J-J’
 Indicates transverse maxillary
growth and should be taken into
account for planning and
evaluation of palatal disjunction
 Mandibular width: Ag-Ag’

Dental to Skeletal relations:
 Lower molar to jaw left: B6 to
J-Ag line
 Lower molar to jaw right: B6
to J- Ag right
 Interpretation: An increased
measure indicates the
likelihood of a buccal
mandibular expansion

 Denture- jaw midline: midline
of denture to ANS-Me

 Occlusal plane tilt: difference
of the height of the occlusal
plane to the ZFL-ZFR plane

Jaw to cranium relations:
 Postural symmetry :
Difference between angles
ZAG-ZA on left and Z-AG-ZA
on right side.
 Normal value: 0°.
 Standard deviation : ± 2°.
 Interpretation: Used for the
diagnosis of asymmetry.

Inner structural problems
 Nasal width : The maximum width
of the nasal cavity.
 Normal value: 25 mm at age 8½. It
increases 0.7 mm per year.
Standard deviation: ± 2 mm.
 Interpretation: Used for the
analysis of the airways. Sometimes
mouth breathing might be due to
a narrow nasal cavity or to
insufficient transverse growth of
the maxilla.

 Nasal height :The distance
between the anterior nasal
spine (ANS) and the Z - Z plane.
 Normal value: 44.5 mm at age
9, increases 1 mm per year.
Standard deviation : ± 3mm
 Facial width :The distance
between points ZA and ZA.
Normal value: 116 mm at age 9.
 It increases 2.4 mm per year.
Standard deviation: ± 3 mm.

 This is a comparative and quantitative posteroanterior
cephalometric analysis. It is not related to normative data.
 The analysis is presented in two forms:
 the comprehensive frontal asymmetry analysis
 summary frontal asymmetry analysis.
 The analyses consist of different components, including
horizontal planes, mandibular morphology, volumetric
comparison, maxillomandibular comparison of asymmetry,
linear asymmetry assessment, maxillomandibular relation,
and frontal vertical proportions
GRUMMONS ANALYSIS
(Grummons and Kappeyne van de Coppello, 1987)

 1. Construction of horizontal
planes
 one connecting the medial
aspects of the
zygomaticofrontal sutures
(Z);
 one connecting the centres of
the zygomatic arches (ZA);
 one connecting the medial
aspects of the jugal processes
(J); and
 one parallel to the Z-plane
through menton.

 2. A midsagittal reference line
(MSR) is constructed from crista
galli (Cg) through the anterior
nasal spine (ANS) to the chin
area
 An alternative way of
constructing the MSR line, if
anatomical variations in the
upper and middle facial regions
exist, is to draw a line from the
midpoint of Z-plane either
through ANS or through the
midpoint of both foramina
rotundum (Fr-Fr line)

 Mandibular morphology
analysis - leftsided and
rightsided triangles are
formed between the head
of the condyle (Co) to the
antegonial notch (Ag) and
menton (Me).
 A vertical line from ANS to
Me visualizes the
midsaggital plane in the
lower face.

 4. Volumetric comparison - four
connected points determine an area,
and here a connection is made
between the points:
 condylion (Co);
 antegonial notch (Ag);
 menton (Mc)
 the intersection with a perpendicular
from Co to MSR
 The two polygons (leftsided and
rightsided) that are defined by these
points can be superimposed with
the aid of a computer program, and
a percentile value of symmetry can
be obtained

 5. Maxillomandibular comparison of
asymmetry –
 four lines are constructed,
perpendicular to MSR, from Ag and
from J, bilaterally.
 Lines connecting Cg and J, and lines
from Cg to Ag, are also drawn.
 Two pairs of triangles are formed in
this way, and each pair is bisected by
MSR. If symmetry is present, the
constructed lines also form the two
triangles, namely J-Cg-J and Ag-Cg-
Ag.

 6. Linear asymmetry assessment
- the linear distance to MSR and
the difference in the vertical
dimension of the perpendicular
projections of bilateral
landmarks to MSR are calculated
for the landmarks Co, NC, J, Ag,
and Me.
 With the use of a computer, left
and right values and the vertical
discrepancies between bilateral
landmarks can be listed

 7. Maxillomandibular relation - during the
X-ray exposure, an 0.014-inch (0.356-cm)
Australian wire is placed across the
mesioocclusal areas of the maxillary first
molars, indicating the functional
posterior occlusal plane.
 The distances from the buccal cusps of
the maxillary first molar to the J-
perpendiculars are Imeasured.
 Lines connecting Ag-Ag and ANS-Me, and
the MSR line, are also drawn to reveal
dental compensations for any skeletal
asymmetry, the so-called
maxillomandibular imbalance.

 8. Frontal vertical proportion analysis
 The following ratios are taken into
consideration (Al: upper central incisor
edge, Bl: lower central incisor edge):
 upper facial ratio - Cg-ANS:Cg-Me= 42%;
 lower facial ratio - ANS-Me:Cg-Me= 58%;
 maxillary ratio - ANS-A1:ANS-Me= 54%;
 total maxillary ratio - ANS-Al:Cg-Me= 31%;
 mandibular ratio - Bl-Me:ANS-Me= 55%;
 total mandibular ratio - Bl-Me:Cg-Me=
32%;
 maxillomandibular ratio - ANS-Al:Bl:Me=
97%

 A method of analysing craniofacial asymmetry with the use
of multiplane posteroanterior cephalometry has been
developed by Grayson et al (1983).
 Landmarks are identified in different frontal planes at
selected depths of the craniofacial complex and
subsequent skeletal midlines are constructed.
 In this way, the analysis enables visualization of midlines
and midpoints in the third (saggital) dimension. The
midpoints and midlines may be combined and a 'warped
midsaggital plane' can be the outcome of this analysis.
GRAYSON ANALYSIS

 In practice, the analysis is
performed on three
different acetate tracing
papers using the same PA
ceph

 On the first acetate sheet,
the orbital rims are outlined,
along with the pvriform
aperture, the maxillary and
mandibiilar incisors, and the
midpoint of the symphysis.
 In this first drawing, the
anatomy of the most
superficial aspect of the
craniofacial complex, as
indicated by plane A, is
presented.

 On the second acetate sheet
the greater and lesser wings of
the sphenoid, the most lateral
cross-section of the zygomatic
arch, the coronoid process, the
maxillary and mandibular first
permanent molars, the body of
the mandible, and the mental
foramina are traced.
 These structures are located
on or near the deeper coronal
plane B.

 The third tracing, containing
structures and landmarks
corresponding to plane C,
includes the upper surface of
the petrous portion of the
temporal bone, the mandibular
condyles with the outer border
of the ramus down to the
gonial angle, and the mastoid
processes with the arch of
temporal and parietal bones
connecting them .

 The midlines of these tracings
are made by connecting the
midpoints of the traced bilateral
points
 If the three tracings are
superimposed, the phenomenon
of warping within the
craniofacial skeleton can be
observed. In most asymmetric
patients, the craniofacial
asymmetry will appear less
severe in the most posterior and
in the deep-lying cranial
structures.

 According to this method (Hewitt, 1975), analysis of
craniofacial asymmetry is performed by dividing the
craniofacial complex in constructed triangles, the so-
called triangulation of the face. The different angles,
triangles and component areas can be compared for
both the left side and the right side
HEWITT ANALYSIS

 The regions that can be
described in this way are:
 the cranial base
 the lateral maxillary region;
 the upper maxillary region;
 the middle maxillary region
 the lower maxillary region
 the dental region; and
 the mandibular region.

 Cranial base region:
Between the extreme
upper extent of the head
of the condyle, extreme
mesial extent of the head
of the condyle and sella
to represent the cranial
base region;

 Lateral maxillary region:
Between sella, mastoidale
and the root of the zygoma
representing the lateral
maxillary region;
 Upper maxillary region:
Joining sella, anterior nasal
spine and the root of the
zygoma representing the
upper maxillary region;

 Middle maxillary region: Drawn
between the root of zygoma, upper
molar points and the anterior nasal
spine representing the right and left
middle maxillary regions;
 Lower maxillary region: Joining
anterior nasal spine, upper molar
points and the point of intersection
of a line drawn between the bilateral
upper molar points and the arbitrary
anatomical axis representing the
right and left lower maxillary regions

 Dental region: Drawn between
upper molar points, upper
incisal point and the point of
intersection of a line joining
the upper molar points and the
anatomical axis representing
the right and left dental
regions;
 Mandibular region: Drawn
between the condylar points,
gonion, and menton to
represent the mandibular
component of the fact

SVANHOLT AND SOLOW ANALYSIS
 This method aims to
analyse one aspect of
transverse craniofacial
development, namely the
relationships between
the midlines of the jaws
and the dental arches

SVANHOLT AND SOLOW ANALYSIS
 This analysis incorporates variables
that have been designed to be zero
in the symmetrical subject
 transverse maxillary position -
mx-om/ORP;
 transverse mandibular position -
m-om/ORP
 transverse jaw relationship -
CPL/MXP
 upper incisal position - isf-
mx/MXP;
 lower incisal position — iif-
m/MLP;
 upper incisal compensation - isf-
mx/m
 lower incisal compensation - iif-
m/mx.

Method of magnification correction for posterioanterior
radiographic cephalometry
Hsiao, chang
angle orthod 1997;67(2):137-142

Posterio anterior cephalometric analysis

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Posterio anterior cephalometric analysis