Cephalometric Analysis Sassouni Analysis The Sassouni analysis was the first to emphasize vertical, as well as horizontal, relationships and the interaction between vertical and horizontal propo

Cephalometric
Analysis

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Sassouni Analysis
The Sassouni analysis was
the first to emphasize vertical,
as well as
horizontal, relationships
and the interaction
between vertical
and horizontal proportions.

Sassouni pointed out that the horizontal
anatomic planes
1.the inclination of the anterior cranial base
2.Frankfort plane
3.palatal plane
4.occlusal plane
5.mandibular plane
tend to converge toward a single point in
well-proportioned faces
The inclination of these planes to each other reflects the
vertical proportiona

If the planes it
ntersect relatively close to the face and diverge
quickly as they pass anteriorly,
the facial proportions are
long anteriorly and short posteriorly.
which predisposes the individual to an open
bite malocclusion.
If the planes are nearly parallel so that they
converge far behind the face and diverge only
slowly as they pass anteriorly, there is a
skeletal predisposition toward anterior deep
bite, and the condition is termed skeletal deep
bite.

as a face becomes more disproportionate,
it is more and more difficult to establish the center for the arc, and the AP evaluation becomes
more and more arbitrary.
Although the total arcial analysis described by Sassouni is no longer widely used, his analysis
of vertical facial proportions has become an integral part of the overall analysis of a patient.
Sassouni evaluated
from the area of intersection of the planes.
Sassouni evaluated the AP position of the
face
and dentition by noting
the relationship of various points to arcs
drawn
from the area of intersection of the planes.

Harvold
using data derived from the growth study
, developed
standards for
the unit length of the maxilla and mandible.
The maxillary unit length is measured from
the anterior border of the mandibular
condyle to the anterior nasal
Diagnosis and Treatment Planning
the mandibular unit length is measured from
the same point to the anterior point of the chin.

The difference between these numbers provides an indication of the size
discrepancy between the jaws.
In analyzing the difference between
maxillary and mandibular unit lengths.
the shorter the vertical distance
between the maxilla and mandible,
the more anteriorly the chin will be placed for any given unit difference,
and vice versa.

The Wits analysis was conceived primarily as a
way to overcome
the limitations of ANB as an indicator of jaw
discrepancy. It is
based on a projection of points A and B to the
occlusal plane,
along which the linear difference between these
points is measured.
If the AP position of the jaws is normal, the
projections from
points A and B will intersect the occlusal plane at
very nearly the
same point. The magnitude of a discrepancy in
the Class II direction
can be estimated by how many millimeters the
point A projection
is in front of the point B projection, and vice
versa for Class III
Wits analysis

The Wits analysis, in contrast to the Harvold
analysis, is influ-
enced by the teeth both horizontally and
vertically horizontally
because points A and B are somewhat
influenced by the dentition
and vertically because the occlusal plane is
determined by the
vertical position of the teeth. It is important for
Wits analysis
to use the functional occlusal plane, drawn
along the maximum
intercuspation of the posterior teeth, not the
Downs analysis
functional plane influenced by the vertical
position of the incisors.

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Even so, this approach fails to distinguish
skeletal discrepancies
from problems caused by displacement of
the dentition, and
it does not specify which jaw is at fault if
there is a skeletal
problem. If the Wits analysis is used, these
limitations must be
kept in mind.

the McNamara analysis (McNamara analysis) which was first published in 1984. The
analysis combines elements from previous analyses such as Ricketts (Ricketts) and
Harvold (Harvold), as well as new measurements to more accurately determine the
position of the jaws and teeth. The main points are explained below
1. References used in the analysis:
" The analysis is based on:
" Anatomical Frankfort Plane: a reference line between the two parts of the orbit
(orbitale) and the exact point of the external ear canal (porion).
" Basion Nasion Line: a line taken from the base of the asyut (basion) to the point of the
nasion (nasion), a reference point at the junction of the nose with the frontal bone.
McNamara Analysis

2. Assessment of the anterior-posterior (AP)
position of the maxilla and mandible:
" The optimal and lower product position is
determined in relation to:
" The vertical line descending from the nasion
(Nasion vertical): The vertical line originates
from the nasion (Nasion) and extends to the
level of the nasion.
" Ideal positions:
" The original perfection (Maxilla): It should be
on or draw attention to this line.
" The mandible (Mandible): It should be some
way behind this line.

3. Comparison of maxillary and
mandibular lengths:
" Harvold s Approach is applied
to compare the lengths of the
maxilla and mandible.
" This comparison helps
determine the proportionality
between the lengths of the jaws
and their compatibility, which is
an important factor in identifying
malocclusion problems or
differences in facial structure.

" The position of the mandible in space is determined based on the
anterior inferior elevation of the face (the distance between the
anterior border of the nasal bone column ANS and the point of the
chin menton).
" The relationship of the maxillary incisor (upper front tooth) is
determined in relation to the maxilla using a line passing through
point A (which represents a reference point in the maxilla) and
perpendicular to the Frankfurt plane. This is very similar to the
Steiner analysis but with a slight difference in the relationship
between the tooth and the NA line.
" For the mandibular incisor (lower front tooth), it is analyzed using
the A-pogonion line, which is the same method used in the Ricketts
analysis.

Strengths of McNamara analysis
(a) Use of the Nasion Perpendicular:
" McNamara analysis links the positions of the jaws using a vertical line starting from the Nasion
point.
" This line shows the anterior-posterior (AP) difference between the jaws in a manner that
approximates the true vertical line, giving a more realistic picture of the jaw position.
" Although the use of a true vertical line is considered more accurate, reliance on an anatomic
reference plane (such as the Frankfurt plane) was necessary due to the use of conventional
radiographs that were not taken in the natural head position (NHP).
b) Use of reliable reference data from the Bolton Sample:
" The analysis is based on standard data from the Bolton sample, a reliable and common data set in
orthodontics.
" The Bolton sample provides reference templates that can be used for initial comparison, making the
results of McNamara analysis very consistent with these templates.

Bolton s Analysis
Bolton analysis gives significance to tooth size. According to Bolton, there exists a ratio
between the mesiodistal width of maxillary and mandibular teeth. Malocclusion occurs
when there is disparity between the mesiodistal dimensions of maxillary and mandibular
teeth. Bolton s analysis helps in determining disproportion in size between maxillary and
mandibular teeth.
The Bolton s ratio can be determined for 6 teeth (Anterior ratio) or for 12 teeth (Overall
ratio).
Abstract:
McNamara analysis focuses on the position of the jaws and teeth in three dimensions using
accurate reference methods, making it a useful tool for diagnosing differences in the jaw
relationship and determining appropriate treatment plans.

A major problem with any analysis based on individual measurements is that any one
dimension is affected by others within the same face.
Not only are the measurements not independent, but it is also quite possible for a
deviation in one relationship to be compensated for wholly or partially by changes in
other relationships.
This applies to both skeletal and dental relationships.
Compensatory changes in the dentition to make the teeth fit, although the jaws do not,
are often the goal of orthodontic treatment.
Counterpart Analysis

The basic idea of interrelated vertical and horizontal dimensions
leading to a balanced or unbalanced facial pattern was first
expressed by Enlow et al in counterpart analysis
_If anterior face height is long, facial balance and proper proportion
are maintained if posterior face height and mandibular ramus height
are also relatively large
_A short posterior face height can lead to a skeletal open bite
tendency, even fanterior face height is normal, because the
proportionality is disturbed.

If both the maxilla and
mandible are normal in length
but the cranial base is long,
the maxilla will be pushed
forward relative to the
mandible, causing maxillary
protrusion.
The same applies
to AP dimensions

Normal Template: Comparing the patient s
proportions to a standard template of average
population norms.
Floating Point Norms: Evaluating the patient s
measurements based on their unique facial type and
the relationships between those measurements.
There are two main methods to apply counterpart
analysis in clinical practice:

The "normal template" refers to comparing the patient s
proportions to a standard template representing average
population norms, used to assess whether the proportions are
normal or abnormal.
Floating point analyzes craniofacial measurements based on
their relationships and the patient s facial type, rather than
comparing individual values to population averages.
It helps identify patterns, even if some values are outside the
normal range, making it useful for growth modification or
orthognathic surgery cases.

Template analysis in cephalometrics involves the graphic
representation of norms to identify patterns and deviations in
craniofacial structures
serve as visual tools for direct comparison of patient structures
with normative data.
Individual cephalometric tracings are digitized onto an (x, y) grid
Group data is converted into composite tracings or templates,
representing average norms.

Schematic Templates (e.g., Michigan, Burlington): Show age-related
changes of specific landmarks.
Anatomically Complete Templates (e.g., Broadbent-Bolton, Alabama):
Provide detailed, age-specific visual references.
Types of Templates:
Steps in Template Analysis
Selecting the Appropriate Template
. Superimpositions for Analysis

Cranial
Base
Superimposition:

Maxillary
Superimposition

Mandibular
Superimposition

Direct Visualization
Age-Specific Comparisons
Complement to Numerical Analysis
Growth Prediction
Diagnosis and Treatment Planning
Computer Integratio
Advantages of
Template
Analysis

Cephalometric Methodology in a Digital Age
In the modern
world with digital images, it is still important to follow a sequence
of steps in cephalometric analysis:

1. Cephalometric Analysis in the Digital Age
(Overview Image)
Cephalometric Analysis in the Digital Age refers to the study and analysis of
cephalometric X-rays using modern digital technologies.
Explanation
â ¬¢ Cephalometric analysis is a method used in dentistry, particularly in orthodontics, to
evaluate the structural relationships of the skull, jaw, and teeth.
â ¬¢ In the digital age, these analyses have evolved from manual measurements on
traditional X-rays to computer-based and AI-assisted techniques, making the process
faster and more accurate.
â ¬¢ Digital imaging enables automated measurements, easy data analysis, improved
diagnostic accuracy, and seamless sharing of information among healthcare professionals
.

A modern digital cephalometric X-ray displayed on
a computer screen
A comparison between traditional (film-based) analysis on one
side and digital analysis with AI-assisted measurements on the
other.
Data overlays, floating measurement lines, and cephalometric
points labeled on the image.
A subtle AI or deep-learning element, such as an algorithm
analyzing the X-ray in the background.
Evolution of Cephalometric Analysis: From Traditional Film to
AI-Assisted Digital Precision

2. Checking for Head Positioning Errors
â ¬¢ Proper patient positioning is crucial to
avoid false interpretations.
â ¬¢ Key indicators of misalignment:
â ¬¢ Car rods (ear rods) should be concentric
unless
the image was intentionally taken
asymmetrically.
â ¬¢ Asymmetry in the upper structures
(orbits, sphenoid wings, key ridges) vs. lower
structures â Likely skeletal asymmetry.
â ¬¢ Even spacing of structures but at an
abnormal scale â Suggests a positioning
error rather than true asymmetry.

Counterpart Analysis
â ¬¢ A method that compares symmetrical anatomical structures (e.g., right and left sides of the
mandible) to detect asymmetries.
â ¬¢ Helps differentiate between true skeletal asymmetry and errors in patient positioning.
â ¬¢ Ensures that discrepancies are due to growth or pathology rather than radiographic
distortion.
Floating Norms
â ¬¢ Unlike fixed cephalometric norms, floating norms adapt to the patientâ ¬!"s individual
characteristics.
â ¬¢ Factors influencing floating norms include:
â ¬¢ Age, gender, and ethnicity (since craniofacial structures vary across populations).
â ¬¢ Skeletal pattern and facial type (e.g., a long-face individual may have different acceptable
vertical measurements than a short-face individual).
â ¬¢ Improves diagnostic accuracy and personalized treatment planning.
3. Counterpart Analysis and Floating Norms

Counterpart AnalysisFloating Norms

Axial CT and Spiral CT have been used for over 40 years but were too
expensive and had high radiation exposure for routine orthodontic use
¬ ¬ CBCT (Cone Beam Computed Tomography) revolutionized
cephalometric analysis by providing
Lower radiation doses compared to medical CT
More accurate 3D assessments of craniofacial structures

Improved visualization of asymmetries and airway spaces
4. The Role of 3D Imaging in Modern Orthodontics

3D Imaging in Modern Orthodontics

Key Takeaways
¬ Cephalometric analysis is more than just numbers understanding the clinical meaning of
measurements is crucial.
¬ Mandibular superimposition helps assess vertical tooth displacement and growth
.changes
.Counterpart analysis ensures accurate symmetry assessment
Floating norms allow for a more individualized approach rather than relying on rigid ¬
.standard values
¬ CBCT has transformed cephalometric evaluation, offering better diagnostic accuracy
.with lower radiation risks

Thank
you