Facial asymmetry

Introduction:
Perfect bilateral body symmetry is more of a theoretic concept that
seldom exists in living organisms
Man frequently experiences functional as well as morphological
asymmetries. For example right and left handedness as well as a
preference for one eye or one leg.
Some of these asymmetries are embryologically rooted and are
associated with asymmetry in the central nervous system.
www.indiandentalacademy.com

Definition of symmetry:
According to Dorland’s medical dictionary symmetry
is”The similar arrangement in form and relationships of
parts around a common axis or on each side of a plane of
the body”
Clinically, symmetry means balance, whereas significant
asymmetry means imbalance.

HISTORY AND STUDIES CONDUCTED:
 Facial asymmetry, being a common phenomenon, was
probably first observed by the artists of Greek statuary.
 Peck and Peck evaluated bilateral facial asymmetry in 52
“exceptionally well-balanced” white adults and observed
that there is less asymmetry and more dimensional stability
as the cranium is approached.
 Woo evaluated ancient Egyptian skulls and found that the
bones of the cranium showed asymmetry with the right
frontal, temporal, and parietal bones being larger. The contra
lateral side of the facial complex exhibited an asymmetry
with the left Zygoma and maxilla being larger.www.indiandentalacademy.com

 Vig and Hewitt evaluated 63 posterioanterior
cephalograms of normal children (i.e no clinical
asymmetry) of contemporary population between the age
of 9-18 yrs,evidenced with, asymmetry found in most of the
children,with the left side being larger.
The cranial base and mandibular regions exhibited a left
side excess. Whereas the maxillary region showed a larger
right side. The dento-alveolar region exhibited the greatest
degree of asymmetry.
Vig and Hewitt concluded that compensatory changes
seem to operate in the development of dento-alveolar
structures.
These changes enable bilateral symmetric function and
maximum intercuspation to occur, thus minimizing the
effects of the underlying asymmetry in the arrangement
and size of the jaws. www.indiandentalacademy.com

 In his longitudinal study, Melnik found no
significant gender deference's by the age of 14 yrs.
They also observed that relative to six years of age
there was an equal probability for mandibular
asymmetry to improve by the age of 16 yrs.
 Study conducted by Lundstorm explained
that asymmetry can be genetic or non-genetic in
origin or may be a combination of both.
 Some of the right –left asymmetry in the
oral cavity could be the result of environmental
factors. (e. g Sucking habits or asymmetric
chewing habits caused by dental caries, extractions
and trauma ). www.indiandentalacademy.com

Lundstrom
Qualitative asymmetry: could
be differences in the size of teeth ,
the location of teeth in the arches, or
the overall position of the arches in
the head.
QualitativeQuantitative
Quantitative asymmetry:
could be differences in the
number of teeth on each side or
the presence of cleft lip or
palate

ETIOLOGY
Genetics Environmental

 Diseases like multiple neurofibromatoses
and hemifacial microsomia which are
having familial incidence associated with
dominant gene, was found to cause facial
asymmetry.
 Clefts of lip or palate are genetically
influenced and result in a facial deformity
with an associated collapse of the maxillary
dental arch.
Genetics:

Severe mandibular deficiency in a 9yr old boy, who was noted at birth
to have a very small mandible and cleft palate and was diagnosed of
having Pierre Robin-Syndrome. Despite considerable postnatal growth
the mandible, mandibular deficiency has persisted.

Environmental:
1. Intra uterine pressures.
2. Pathologic changes.
3. Trauma &infection.
4. Nerve injury.

1. Intra uterine pressure:
During pregnancy and significant pressure at the
birth canal during parturition can have observable
effects on the bones of the fetal skull. The molding of
the parietal and facial bones from these pressures
can result in facial asymmetry. These effects are
generally transient with a rapid restoration of the
normal relationships of the skull within a few weeks
to several months.
Mid face deficiency in a 3 yr old
child, still apparent though much
improved from the severe
deficiency that was present at birth
because of the intra-uterine
molding

2. Pathological changes:
Craniofacial asymmetry can be caused by
environmental factors including pathological changes
that are not necessarily congenital in nature.
osteochondroma of the mandibular condyle results in
facial asymmetry, open-bite on the involved side, and
mandibular deviation.
Acromegaly leading to
facial asymmetry,
because of the differential
growth of the mandible.

3. Trauma & Infection:
Trauma & Infection within the T.M.J could result in
ankylosis of the condyle to the temporal bone,
ankylosis in the growing child causes unilateral
mandibular underdevelopment on the affected side
leading to facial asymmetry.
Unilateral fractures of the mandible can display
varying degrees of facial disfigurement and
asymmetry.
Facial asymmetry developed in this boy
after fracture of the left mandibular
condylar process at age of 5, because
scarring in the fractured area, prevented
normal translation of the mandible on
the side during growth. Trauma is the
frequent cause of asymmetry of this typewww.indiandentalacademy.com

4. Nerve injury:
Damage to nerve may indirectly lead to
asymmetry from loss of muscle function and tone.

V. Structural classification of dentofacial
asymmetries:
Asymmetries can be classified according to the
structures that are involved.
A. Dental asymmetries
B. Skeletal asymmetries
C. Muscular and soft tissue asymmetries
D. Functional asymmetries

A. Dental asymmetries:
Dental asymmetries can be caused by local factors
such as early loss of primary teeth, congenitally
missing teeth, and habits such as thumb sucking.
Lack of exactness in genetic expression affects the
teeth on the right and left sides, causes asymmetries
in mesio-distal crown diameters.
According to Garn, Lewis, Kerewsky asymmetry
generally does not involve an entire side of the
arch. On the other hand, teeth in the same
morphologic class tend to have the same direction
of asymmetry. For example, if the maxillary first
premolar is larger on the right side, but the molars
need not be larger on that side.www.indiandentalacademy.com

In addition, asymmetry tends to be greater for
the more distal tooth in each morphologic
class. (i e, the lateral incisors, second
premolars,and third molars). Asymmetry may
also be confined to the shape of the dental
arches.
B. Skeletal Asymmetries:
The skeletal asymmetries may involve one
bone such as the maxilla or the mandible, or
they may involve a number of skeletal and
muscular structures on one side of the face e.g-
Hemifacial microsomia.www.indiandentalacademy.com

C. Muscular and soft tissue Asymmetries.
Facial disproportions and midline discripancies could be the
result of muscular and soft tissue asymmetry such as with
Hemifacial Atrophy or cerebral palsy.
Sometimes muscle size is ill proportioned as in Masseter
Hypertrophy, or Dermatomyositis and also from neoplasms.
Abnormal muscle function often results in skeletal and dental
deviations.(Wry Neck)
TORTICOLLIS: Excessive tonic
contraction of the muscles such as
sternocleidomastoid, leads to the facial
asymmetry because of the growth
restriction on the affected side.

D. Functional Asymmetry.
Functional asymmetries can result from the
mandible being deflected laterally or
anterioposteriorly, occlusal interferences
prevent proper intercuspation in centric
relation.

These functional deviations may be
caused by a constricted maxillary arch or by a
more localized factor such as a mal-posed
tooth.
The abnormal initial tooth contact in
centric relation results in subsequent
mandibular displacement in centric occlusion.
T.M.J derangements and co-ordination
accompanied by an anteriorly displaced disk
without reduction may result in a midline shift
during opening caused by interferences in
mandibular translation on affected side.www.indiandentalacademy.com

Diagnosis
CLINICAL
EXAMINATION
RADIOGRAPHIC
EXAMINATION
PHOTOGRAPHIC
ANALYSIS
In diagnosing facial and dental asymmetries, a thorough
clinical examination and radiographic surveys are
necessary to determine the extent of the soft tissue,
skeletal,dental, and functional involvement.www.indiandentalacademy.com

An important aspect of diagnosing Asymmetry is
obtained with a thorough medical and dental history
including:
History of trauma,
Arthritis,
Progressive changes in the occlusion
VI. Diagnosis:

Evaluation of dental midlines.
Vertical occlusal evaluation.
Transverse and anteroposterior occlusal
evaluation.
Transverse-facial, skeletal, and soft
tissue evaluation.
Clinical examination:
Clinical examination can reveal asymmetry in the
Vertical, Anteroposterior or Lateral directions.

Evaluation of dental midlines:
Mouth Open.
In Centric Relation.
At Initial Contact.
In Centric Occlusion.
Clinical examination should include an evaluation of
the dental midlines in the following positions:

True asymmetries of skeletal or dental origins, if
uncomplicated by other factors, exhibit similar
midline discrepancies in centric relation and in
centric occlusion.
On the other hand, asymmetries caused by occlusal
interferences may result in a mandibular functional
shift following initial tooth contact.The shift can be
either in the same or opposite direction of the dental
or skeletal discrepancy and may either accentuate or
mask the asymmetry. The patient should also be
evaluated to detect functional asymmetries related to
T.M.J derangements.www.indiandentalacademy.com

Vertical occlusal evaluation:
Increase in the vertical length of the condyle and ramus will
usually lead to canted occlusal plane. Similarly, the maxilla or
temporal bone supporting the glenoid fossa could be at different
levels on each side of the head may also lead to canted occlusal
plane.
The severity of the canting of mandibular and maxillary occlusal planes is
assessed by asking the patient to bite on a tongue blade and relating it to the
interpupillary plane. www.indiandentalacademy.com

Vertical skeletal asymmetries associated with progressively
developing unilateral open-bites may be the result of condylar
hyperplasia or neoplasia.

Transverse and anteroposterior occlusal evaluation:
Asymmetry In the buccolingual relationship should be
carefully diagnosed to determine if it is Skeletal, Dental,
or Functional. (e.g. a unilateral posterior crossbite)
If there is a mandibular deviation from centric relation to
centric occlusion, the lower dental midline and chin point
should be compared with other mid sagittal dental,
skeletal, and soft tissue land marks in the open, initial
contact, and closed mandibular positions.

In some long standing cases of functional shift, where the
assessing of functional shift is difficult, occlusal splint may be
constructed for the patient to wear, which allows the
musculature to freely guide the mandible to its proper
relationship without the distracting influence of the occlusal
interferences.

Lundstrom found that using the maxillary raphe as a
reference line for the median plane is not reliable in
determining maxillary asymmetries in either the
anteroposterior or lateral directions.
Therefore each dental arch should be evaluated
separately clinically, and using oriented dental casts to
accurately determine the bilateral symmetry of the
molar and canine positions.
Placing a transparent ruled grid
over the dental cast that the grid
axis is in the midline makes it easier
to spot asymmetries in arch form
and in tooth position

NOTE: Examination of the overall shape of the maxillary and
mandibular arches from an occlusal view may disclose not only
side-side asymmetries but also differences in the buccolingual
angulation of the teeth.
NOTE: Expansion of the dental units to correct a cross-
bite in the presence of a skeletal constriction may
adversely influence the stability of the correction.
NOTE: Moving already tipped posterior teeth further
buccally to correct the cross-bite will be associated with
greater relapse .

Arch asymmetry could also be caused by rotation of
the whole maxilla or mandible. The diagnosis of a
rotary displacement of the maxilla may require
further evaluation by mounting the dental casts on
an anatomic articulator using a face bow transfer.

Transverse facial, skeletal, and soft tissue evaluation.
The evaluation of facial asymmetry is one of the
most important aspect of the clinical evaluation.
It includes-
1. Comparison of bilateral structures in both
the transverse and vertical directions.
2. Check the presence of other abnormalities.
3. Observe for the body posture.

4. Deviations in the dorsum and tip of the nose as well
as the philtrum and chin point, need to be
determined.
5. Asymmetries in the mandible may be observed
clinically from a frontal view by observing the point
of the chin as it relates to the rest of the facial
structures.
6. Looking at the mandible from an inferior view
sometimes helps to determine the extent of its
involvement in relation to the rest of the face.

Sagittal facial proportions: “The rule of fifths”
From the midsagittal plane the ideal face is comprised of
equal fifths, all approximately equal to one eye width.
Medial limbus commisure
“RULE OF FIFTHS”
FRONTAL FACIAL ANALYSIS
INNER CANTHI- ALAR BASES

For ideal proportions from the frontal view,the
width of the base of the nose should be approximately
the same as the inter-inner-canthal distance, while the
width of the mouth should approximate the distance
between the irises.

Radiographic examination:
Lateral cephalograms.
Panoramic radiograph.
Posteroanterior projection
T.M.J imaging.

Radiographic examination
Lateral cephalograms:
Interpretation of the lateral cephalogram in diagnosing
the asymmetries is of limited value.
Provides little useful information on asymmeties in
Ramal height, Mandibular length, and Gonial angle.
DRAW BACKS:
 Super-imposing of right and left structures and
magnification of structures.
 In addition ear rods are oriented to the external
auditory meatus, assuming it as a symmetric
anatomic structure, but in reality it may vary in
more than one plane of spacewww.indiandentalacademy.com

Panoramic radiograph:
Panoramic radiograph is a useful projection to survey
the dental bony structures of the maxilla and
mandible to determine the presence of-
1.Gross pathologic condition
2.Missing or supernumerary teeth.
3.Gross comparison of shape of mandibular
ramus and condyles on both sides.

Posteroanterior projection:
Is a valuable tool in diagnosing the asymmetry
as the structures are located at relatively equal
distances from the film and X-ray source there
by minimizing the magnifications and distortion.
Posteroanterior cephalograms can be obtained
in centric occlusion as well as with the mouth
open. The latter position might help determine
the extent of functional deviation,if any is
present.

Posteroanterior and basilar cephalometric views are useful in
evaluating the cases of dentoalveolar and facial
asymmetries,dental and skeletal cross-bites, and functional
mandibular displacements.
Various analysis are:
 Rickett’s analysis
 Svanholt and solow analysis
 Grummon’s analysis
 Grayson’s analysis
 Hewitt analysis
 Chierici method www.indiandentalacademy.com

GRUMMONS ANALYSIS
This is a comparative and quantitative
posteroanterior analysis.
It is not related to normative data.
GRUMMONS ANALYSIS
Maxillomandibular
comparison of
asymmetry.
Linear
asymmetry
assessment.

MAXILLO-MANDIBULAR COMPARISON OF
ASYMMETRY.
Four lines are constructed:
 Lines connecting CG and J and
CG to AG
 Perpendicular to MSR from
AG(Antegonial notch)
Two pairs of triangles are
formed and each pair is
bisected by MSR.
If asymmetry is present, the constructed lines also
form the two triangles namely J-CG-Jwww.indiandentalacademy.com

The linear distance to MSR and the difference in the
vertical dimension of the perpendicular projections of
the bilateral landmarks to MSRare calculated for the
landmarks CO, NC, J, AG, and ME.
LINEAR ASYMMETRY ASSESMENT

SUBMENTO VERTEX VIEW
Sub-mento-vertical projections made on 10 subjects by
CLIFFTON. T. FORSBERG, and CHARLES.J.BURSTONE
and the resulting publication of AJO 1984 March, infers
that the Sub-mento-vertical projection is particularly more
useful than the PA projection.
The S-V projection allows the utilization of anatomic
landmarks on the cranial base,remote from the facial bones,
for determination of the mid-sagittal axis,which is more
reliable.

Infraorbital pointer is used to position
patient's Frankfort horizontal plane
parallel to the film cassette.
Asymmetry is noted in the
cranial base and maxilla. The
mandible is relatively
symmetric.www.indiandentalacademy.com

T.M.J imaging:
Comprehensive T.M.J imaging may include one or more of
the following procedures:
 Conventional Radiographs.
 Conventional Tomography.
 Computerized Tomography.
 Arthroscopy and Videofluroscopy.
 Magnetic Resonance Imaging.
 Radionuclide imaging to determine bone turnover
activities.

Photographic analysis rules out the major
disproportions and asymmetries of the face in
the transverse and vertical planes.
It is absolutely essential for the camera to be
placed perpendicular to the facial midline
during the exposure, otherwise it might lead to
major discrepancies between the relative
patterns of the right and left facial contours.
Photographic analysis:

Photographic analysis:
VERTICAL REFERENCE PLANE:
Soft tissue nasion-Subnasale
UPPER HORIZONTAL PLANE:
Bipupillary plane
LOWER . HORIZONTAL PLANE:
Parellel to Bipupillry
plane through
the Stomion.
BILATERAL MARKING OF ORBITAL
POINT.
Various reference planes:

PHOTOGRAPHIC REPRESENTATION OF FACIAL ASYMMETRY:
TRUE FRONTAL PICTURE
11 yr –old boy with a noticeable difference
between the right and left sides of the face.
FIRST COMPOSITE FRONTAL PICTURE
Altered facial form after photomontage of the
two right sides of the face.
SECOND COMPOSITE FRONTAL PICTURE
Frontal view after photomontage of the two left
sides.
THE PHOTOGRAPHIC METHOD ILLUSTRATES THE DIFFERENCE IN
THE CONFIGURATION OF THE TWO SIDES OF THE FACE.

SYSTEMATIC SEQUENCE OF
EVALUATION OF DENTAL AND FACIAL
ASYMMETRY
 Nasal tip to mid sagittal plane.
 Maxillary Denatal Midline to Midsagittal plane
 Maxillary Dental midline to mandibular Dental
midline.
 Mandibular dental midline to Midsymphysis.
 Midsymphysis to Midsagittal plane

 Nasal tip to mid sagittal plane:
 The evaluation of the nasal tip is best
visualized by having the patient elevate the head
slightly and evaluating the position of the tip by
visualizing the midsagittal plane along the long
axis of the face.
Deviation of the nasal tip from the mid-sagittal plane
may be secondary to the following:
 Traumatic injury to the nose.
 Deviation of the nasal septal cartilage,
sometimes including vomer.

 Unfortunate stigmata of nasal plastic
surgery.
 Congenital nasal stenosis, which in the vestibule
can affect the lateral angle.
 Nasal deformities that occur in unilateral cleft-
lip nose.

Maxillary Denatal Midline to Midsagittal plane
This relationship is best visualized by looking at the patient with
his or her head slightly elevated.
Deviations of the maxillary dental midline from the midsagittal
plane may include the following:
Maxillary dental midline discrepancy
Missing tooth/teeth
 Such as congenitally missing lateral incisors,
 extracted cuspids.
Maxillary rotation:
-Associated with the post-traumatic maxillary reconstruction.
-Maxillary rotation generally exhibits dental cross-bites.

It is desirable that these midlines should be coincident.
A discrepancy between these two midlines may be a result of
the following:
Maxillary dental midline shift.
Mandibular dental midline shift.
Mandibular asymmetry.
Functional shift of the mandible laterally.
 Maxillary Dental midline to mandibular
Dental midline.

Mandibular dental midline to Midsymphysis.
 The relationship is best visualized
by standing behind the patient and
viewing the lower arch from above.
 Having the patient open his or her
mouth to see the lower arch and its
midline relation to the body of the
mandible and the symphsis.

Lower dental midline descripancies from the midsymphysis are
generally a result of :
 Dental crowding with a shift of the lower
incisors.
 Prematurely missing primary canines or other
primary or other primary teeth in the
adolescent.
 Congenitally missing teeth or premature loss
of teeth with a resultant midline movement.
 A missing lower incisor.

Midsymphysis to Midsagittal plane
 The relationship of the midsymphysis to the
midsagittal plane is best visualized through a
submental view.
 By asking the patient to elevate his or her head so
that we can see straight up the midsagittal plane.
 Deviation of the midsymphysis from the
midsagittal plane is most often a result of a
functional mandibular shift or a true mandibular
asymmetry.

LOCALIZATION OF ASYMMETRY:
ANATOMIC
APPROACH
TRIANGULATION
APPROACH
BISECTION
APPROCH

 Once a posteroanterior film has been obtained ,
it must be quantitatively evaluated to
determine the extent of the asymmetry
present. The structures to be used in the
construction of the midsagittal reference plane
need to have a relatively high degree of
symmetry.
LOCALIZATION OF ASYMMETRY:

ANATOMIC APPROACH:
Harvold found that Zygomatico –frontal structures
and crista galli are relatively symmetric structures
as compared to other facial land marks that are
further distant from the cranial base.
Construction of the horizontal line through the
zygomatico frontal sutures to act as the horizontal
axis.
A vertical line perpendicular to the horizontal axis
is constructed to pass through and bisect the base of
the crista galli. This vertical line aprroximates the
anatomic midsagittal plane of the head.

Perpendiculars from bilateral structures can
now be constructed to this mid-sagittal vertical
reference line.
The differences between the the projections
from the two sides are then measured and
compared to quantify discrepancies in height as
well as in the distances between the bilateral
structures and the midline. In addition, the
maxillary and mandibular dental midlines are
compared to the skeletal midline.

BISECTION APPROACH:
In cases where it is difficult to accurately identify
Crista Galli or the Zygomatico-frontal sutures,the
bisection approach may be used.
With the bisection approach bilateral landmarks are
located and bisected. A reference line is then
constructed, passing through as many of the mid-points
of these bilateral landmarks.
If a mid-point is obviously off in relation to most other
midpoints of the cranium and face, it may be advisable
to exclude such a point when constructing the
midline.Evaluation of the bilateral asymmetry then
follows the same principles as with the anatomic
approach.

TRIANGULATION APPROACH:
The triangulation approach can be used to
a study the relative asymmetry of the
component areas of the facial complex.
Following the identification of bilateral
structures and the midline on the
radiograph, triangles are constructed that
divide the face in to various components.
The right and left triangles are then
compared for symmetry.

TREATMENT:
TREATMENT FOR DENTAL ASYMMETRIES:
True dental asymmetries such as cases with a congenitally
missing lateral incisor or a second premolar are often
treated orthodontically.
Asymmetric extraction sequences and asymmetric
mechanics (e.g ., Cl-III elastics on one side and Cl-II
elastics on the other with oblique elastics anteriorly) can
also be used to correct dental arch asymmetries.Composite
build ups or prosthodontic restorations may be indicated
with pronounced tooth irregularities.

TREATMENT FOR FUNCTIONAL ASYMMETRIES:
 Mild deviations caused by functional shifts are
sometimes corrected with minor occlusal
Adjustments
 More severe deviations need orthodontic treatment
to align the teeth and to obtain proper function.
 Occlusal splints may be necessary to properly
evaluate the presence and extent of the functional shift
by eliminating the habitual posturing and de-
programming the musculature.
 Because functional shift can also be the result of a
skeletal asymmetry, rapid maxillary expansion,
orthognathic surgery, and orthodontic treatment may
be indicated in the management of these cases.www.indiandentalacademy.com

TREATMENT FOR SKELETAL ASYMMETRIES:
 In growing Individuals, orthopedic appliances in
conjunction with orthodontics are used to help improve or
correct the developing imbalance.
 Asymmetries of a skeletal nature treated with
orthodontics alone may dictate certain compromises that
need to be explained to the patient before treatment is
initiated.
 Severe discrepancies may require a combination of
surgery and orthodontics.
 Abnormalities of the coronoid and condylar processes
as well as in the position and shape of the articular
disks should be considered when limited opening, acute mal-
occlusions, or mandibular deviations are found.

TREATMENT FOR SOFT TISSUE ASYMMETRIES:
 Deformities caused by sift tissue imbalance
can be treated by either augmentation or
reduction surgery.
 Augmentations include the use of bone
grafts and silicone implants to re-contour the
desired areas of the face.
 With the mild dental, skeletal, and soft
tissue deviations the advisability of treatment
should be carefully considered.

CONCLUSION
Asymmetry in the craniofacial areas can be recognized
as differences in the size or relationships of the two
sides of the face. This may be the result of
discrepancies either in the form of individual bones or a
mal-position of one or more bones in the craniofacial
complex. The asymmetry may also be limited to the
overlying soft tissues.
The point at which normal asymmetry becomes
abnormal cannot be easily defined and is often
determined by clinicians sense of balance and the
patients perception of the imbalance.

SPECIAL THANKS TO MY
GUIDE……….

Facial asymmetry

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Facial asymmetry