Management of deviated midline

anagement Of
Deviated Midline
INDIAN DENTAL ACADEMY
Leader in continuing dental education
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Contents
Introduction
Definition
Classification
Etiological factors causing the midline
deviation
Diagnosis of the midline deviation
Management of the deviated midline

Introduction
Perfect bilateral symmetry is largely a
theoretical concept that seldom exists in the
living organisms. Asymmetry of the face
and dentition is a naturally occurring
phenomenon.
Relative symmetry and midline
coordination are basic to an appreciation of
facial harmony and balance.www.indiandentalacademy.com

Definition
Symmetry is defined as equality or correspondence in forms
of parts distributed around a centre or an axis at the two
extreme pole or on the two opposite sides of the body.
Asymmetry in craniofacial areas can be recognized as
difference in size or relationship of the two sides of the face.
This may be a result of discrepancies in the form of
individual bones or malposition of one or more bones in the
craniofacial complex, or the asymmetry may be confined to
the soft tissue.

Classification
Sarver evaluates the facial symmetry under the
following reference planes
Nasal tip to the mid sagittal plane
Maxillary dental midline to the mid sagittal plane
Maxillary dental midline to mandibular dental
midline
Mandibular dental midline to mid symphysis
Mid symphysis to the mid sagittal plane

Midlines can also be classified as
Dental midline – related to the symmetry of the
dentition of the maxilla and mandible
Functional midline - related to the functions of
the stomatognathic system
Skeletal midline – related to the symmetry of the
osseous structures of the craniofacial region
Soft tissue midline – related to the symmetry of
the soft tissue of the craniofacial regionwww.indiandentalacademy.com

Functional midline
Centric relation is the relationship of the mandible
to the cranium when the condyles are in an
orthopaedically stable position. It is the most
retruded position of the condyle.{superoanterior
position}
Centric occlusion is the maximum intercuspation of
the teeth
Postural rest position - the synergistic and the
antagonistic muscular components are in dynamic
equilibrium. The balance is maintained with
minimal basic muscle tonus.www.indiandentalacademy.com

Postural rest position
Postural rest position
Myostatic anti stretch
reflex
Permanent
exogenous factors
Gravity Dependent and
altered with the head
positionwww.indiandentalacademy.com

Movement of the mandible
During the closing maneuver from the rest position
to the habitual occlusion two phases of the
movement can be observed
The free phase - from the postural rest position to the
point of initial contact or occlusal prematurity
The articular phase - from the initial contact position to
the centric occlusion or habitual occlusal position

Laterocclusion
When the occlusal prematurity is present
Midline shift observed only during the centric occlusion
or intercuspation.
During the postural rest position the midlines are
coincident and well centered .
The mandible slides laterally from the rest position into a
cross bite and is caused by the tooth guidance,after the
initial contact of the free phase
LATEROCCLUSION
also called the pseudo cross bitewww.indiandentalacademy.com

Mandibular dental midline
coincident with the facial
midline in postural rest position
Mandibular dental
midline shifted to the
right in habitual
occlusion

Postural rest position
Initial contact
Habitual occlusion

Laterognathy
Midline shift is present in both centric occlusion and
in the postural rest position
This condition is generally seen in the true
asymmetry of the mandible
Functional appliances have poor prognosis
Surgical correction required
LATEROGNATHY

Mandibular dental midline not
midline in postural rest position
Mandibular dental midline not
midline in habitual occlusion

Etiology
One of the common etiologic factor for the
deviation of midline, irrespective of the type of the
midline shift is GENETICS – due to the genetic
imperfections in the mechanism which was meant to
create symmetry and environmental factors
producing decided right and left differences
Examples –
 multiple neurofibromatosis- familial incidence
associated with dominant gene
Hemifacial microsomia
Cleft lip and palatewww.indiandentalacademy.com

Lundstorm classified the etiological factors as
Genetic
Non genetic
combination
Another classification by the same author
Qualitative –
Size of the teeth
Location in the arches
Position of the arches
Quantitative
Differences in the number of teeth on each side or the presence
of cleft lip or palatewww.indiandentalacademy.com

Midline diastema
Mesiodens
Generalized spacing
Frenal attachments
Congenital absence of a tooth
Morphological variation of a tooth eg. Microdontia or macrodontia
Asymmetrical exfoliation
Retained deciduous teeth
Early loss of primary teeth
Crowding
Trauma
Habits such as thumb sucking and tongue thrusting
Traumatic occlusion leading to pathological migration
Pathological condition such as cysts
EtiologyDental midline shift

The upper right central incisor
has shifted to the right due to the
congenital absence of lateral
incisor
The contact point upper central
incisor do not coincide with the
center of the philtrum

Functional midline shift
Neurological disturbances
Disturbances in the tooth – tooth inter relationship
Anterior cross bite
Posterior cross bite
Contracted maxillary arch
Any other occlusal prematurity preventing the smooth
closure from the free phase to the articular phase
Compensation of a skeletal discrepancy
Etiology

Skeletal midline shift
Genetics
Local
Trauma
Ankylosis
Damage to nerve – loss
of muscle function and
tone
Pathological state in
the form of cysts and
tumors
Unilateral posterior
edentulous area
Post operative sequale
of orthognathic surgery
Etiology
Temperomandibular
joint
Systemic
Intrauterine pressure
during pregnancy and
significant pressure in the
birth canal
Condylar resorption
Rheumatoid arthritis
Systemic Lupus
Erythamatosis
Sjogren’s syndrome
Marfan’s syndromewww.indiandentalacademy.com

Soft tissue midline shift
Neurological disturbances such as cerebral palsy
and Hemifacial microsomia
Massetric hypertrophy
Trauma
Scars including surgical scars
Dermatomyositis
Neoplasm
Adaptation to the existing skeletal asymmetries
Etiology

Diagnosis
Asymmetry of the face is one of the more difficult problems
with which the orthodontists have to contend and which
presents serious diagnostic problems. The recognition of
actual site of asymmetry is essential for correct treatment
planning.
The point at which normal symmetry becomes abnormal
cannot be easily identified and is often identified by the
clinician’s sense of balance and patient’s perception of their
imbalance.
Vig and Hewitt studywww.indiandentalacademy.com

Diagnostic aids
History
Clinical examination
Photographic evaluation
Radiographic examination
Orientation of the cast
Occlusograms
Computed tomography
Video cepalometry
Multi view fluoroscopy

History
Patient history is important for the diagnosis, as it
aids in the knowledge of
Exfoliation of the primary teeth
Extractions undergone if any
Trauma
Familial tendencies
Congenital problems
Surgical procedurewww.indiandentalacademy.com

Clinical examination
Frontal view evaluation
Nasal tip to mid sagittal plane
Maxillary dental midline to midsagittal plane
Mandibular dental midline to midsagittal plane
Mandibular dental midline to midsymphysis
Midsymphysis to midsagittal plane
Evaluation of dental midline in the
Mouth open
Centric relation
At initial contact
Centric occlusion www.indiandentalacademy.com

Other features to be noted during clinical
examination are
Missing and supernumerary teeth
Tooth shape and size
Arch form symmetry
Frenal attachments

Photographic evaluation

Advantages
Inexpensive
No exposure to potentially harmful radiation
Better evaluation of the harmony relationship
among the craniofacial structure including the
contribution of muscle and adipose tissue
Readily used to posture the head and face and to
compare these with the relationship existing among
the different craniofacial structureswww.indiandentalacademy.com

Study cast analysis

Occlusograms
 1992, JCO, Occlusograms in Orthodontic Treatment Planning -
RICHARD D. FABER,
Lower occlusal tracing
placed over arch
symmetry chart to
establish midline and
perpendicular
reference crosshairs.

Radiographs
OPG
Posteroanterior view (PA view)
Submento vertex
Lateral cephalometric radiograph
IOPA

Orthopantamogram
Temperomandibular joint can be viewed
 Asymmetry of the body or ramus of the mandible
Missing or supernumerary teeth
Pathological condition like cysts and neoplasmwww.indiandentalacademy.com

Rickett’s analysis
Svanholt and Solow
Grummons analysis
Grayson analysis
Hewitt analysis
Posteroanterior view

Landmarks of Grummons analysis
JCO, 1987, A Frontal Asymmetry Analysis – Duane et alwww.indiandentalacademy.com

HORIZONTAL
PLANE
MANDIBULAR
MORPHOLOGY
LINEAR
ASYMMETRY
VOLUMETRIC
EXPANSION

MAXILLO
MANDIBULAR
FRONTAL
VERTICAL
PROPORTION

JCO 1982: Orthognathic and Craniofacial Surgical Diagnosis
and Treatment Planning: A Visual Approach. Farhad et al
Horizontal and vertical lines are drawn to indicate areas of
asymmetry. www.indiandentalacademy.com

Posteroanterior view
Disadvantages
Midline assessment is difficult
Difficulty in reproducing head posture
Difficulty in identifying landmarks because of
superimposition of structures
Exposure to radiation

Submentovertex (SV)
Berger was the first to suggest the use of SV (problems and
promises of basilar view cephalogram) in orthodontics.
Gibert associated the film cassette parallel to the FH plane
Pearson found exceptional degree of symmetry in the
sphenoid bone
Keith and Campion used sphenoid bone as a fixed reference
in comparing the development of growth of skull
Marmary and associates showed that perpendicular bisector
of a line joining the foramina spinosa was a reliable and
accurate midline
Ritucci and burstone developed the ceph system for the
assessment of craniofacial regionwww.indiandentalacademy.com

Diagnosis and treatment planning of skeletal asymmetry
with submento vertex radiograph, 1984 AJO, Forsberg et al

Basilar multi plane cephalometric analysis
Put forward by Grayson et al 1985, AJO
Developed to facilitate the measurement of the
craniofacial complex from the submento vertex
view.
Basilar view is a two dimensional representation of
a three dimensional object
The cranium can be reconstructed in 3 dimensions
from the basilar view cephalograph by separately
tracing each of the three suggested horizontal plane

Multi View Fluoroscopy
Permits three dimensional analysis of the
oropharyngeal components in motion
Combines the lateral, frontal and basal projection
Contrast medium is used to define the soft tissue
landmarks and to determine their function during the
variety of functions of the stomatognathic system.

Management
Differential diagnosis and appropriate inter arch and
intra arch mechanotherapy is necessary to determine
and correct the midline problem.
Review of literature
Breakspear advocates adapting the occlusion by
‘stoning’- occlusal equilibration. This mode of
treatment allows the settling of occlusion to
function better but not to correct the dental or
facial asymmetry.

Paul Lewis – dental asymmetries are more
commonly seen with class II malocclusion
The correction of mid line caused by the shift of the
mandible or rotation of the mandible is attempted only
after teeth in both arches are put into quite ideal
occlusion.
In midline deviation that occurs with posterior cross
bite,the narrow maxillary arch must be expanded first.
A class II elastic worn from a hook or sliding yoke on
the side towards which the mandible has shifted. A
second elastic is worn across the anterior teeth to swing
or pivot the mandible until midline correction is
achieved. www.indiandentalacademy.com

Angle’s treatment modality
. From Angle EH. Malocclusion of the teeth, 1907.
 Angle suggests
Class III elastic with
tandem anterior
diagonal elastic in
conjunction with
area expansion for
correction of midline
discrepancies.

Begg mechanotherapy
. From Begg PR, Kesling P. Begg orthodontic
theory and technique, 3rd ed.
Space-closing elastics
and Class II
intermaxillary elastics
applied at start of
second stage of
treatment.
Anterior diagonal
elastics,class II elastics
and class III elastics
and Uprighting springs
(Mollenhaeur) www.indiandentalacademy.com

Wick Alexander
Midline is corrected during the finishing stages
 ¼ inch, 6 ounce elastic ,one end attached to maxillary
lateral bracket and adjacent central bracket. The other end
attached to mandibular lateral incisor bracket on the
opposite side.
 In case of class II tendency, a class II elastic is worn and in
class III tendency,class III elastics are worn.
 The class II elastic is attached to the maxillary lateral
incisor and mandibular second molar. The two elastics
impart roughly parallel force vectors.

 In cases of midline discrepancy in class I buccal
relationship, only the midline elastic is worn, extra class II
or class III elastics are not worn.
Midline elastics are worn during the finishing stages of
active treatment with one exception. In an extraction case
during space closure the midline may be shifted
significantly, during space closure the elastic can be
attached to the closing loops. This will help to control the
direction of space closure, thus improving the midline.
Over correction
Ideal occlusion and midline

Correction of midline in class II subdivision
Suppose class II on right and class I on left, the
midline is generally shifted to the left
To re establish the midline the extraction pattern
would be
Upper arch – left side – second premolar
right side – first premolar
Lower arch - left side – first premolar
right side – second premolar
4 5
5 4

Gianelly
Introduced a biomechanical system with second
order bends to move the teeth distally and create
space for the midline correction
Class II and class III elastics are used to enhance the
couple force systems
Gianelly AA, Paul IA.
A procedure for midline correction. AJO 1970www.indiandentalacademy.com

Strang
 Double vertical spring loop auxiliary adjusted for the mass
movement of the four incisor teeth to the left. From strang
R, Thompson W. A textbook of orthodontia, 1958.

Source: AJO-DO , 1990 Jun : The midline – diagnosis
and treatment, Jerrold

Profitt
Minor midline discrepancy can be corrected during
the finishing stages
Large discrepancy correction becomes difficult after
the closure of extraction spaces
A correct maxillary midline is more important for
good facial aesthetics and mild mandibular midline
creates no esthetic difficulty
Use of class II or class III elastics bilaterally with a
heavier force on one side
Combination class II and class III elastics

Parallel cross elastics used to correct mild tranverse
discrepancy leading to the lateral mandibular shift
late in the treatment
Anterior diagonal elastics with rectangular arch wire
in the lower arch and a round wire in the upper to
shift the maxillary arch

When midlines are
deviated to the opposite
side,correction
accomplished with
Uprighting springs
Functions are normal
Not healthy from
periodontal point of view
Esthetic results are poor

Careful attention to midline coordination and
attendant facial symmetry helps to achieve
Maximum intercuspation
Normal function with anterior disocclusion and without
any loading of the anteriors
Stability in the finished result
Promotion of anterior dental and facial esthetics
Decreased potential for Temperomandibular joint
dysfunction

Functional midline deviation
The functional midline shift can be corrected
by unlocking the mandible
Removal of the occlusal prematurities
Expansion of the upper arch
Functional appliances
Inter arch elasticswww.indiandentalacademy.com

Surgical options
Nasal tip to midsagittal plane
Rhinoplasty
Camouflaging grafting of the tip of and /or the dorsum
Maxillary dental midline
Subapical procedure to rotate midlines
Mandibular dental midline to symphysis
Subapical procedures to rotate the mandible
Mandibular asymmetry{functional mandibular
shift}
Two or three piece maxillary expansion via Le fort I
osteotomy
Surgically assisted maxillary expansionwww.indiandentalacademy.com

True mandibular asymmetry
Distraction osteogenesis
Bilateral ramal osteotomies
Camouflage through bone grafting or alloplastic
augmentation
Transverse cant of the maxilla
Maxillo mandibular surgery
Chin asymmetry
Rotational genioplasty
Lateral or vertical movement of chin via inferior border
osteotomy
Camouflage via bone graft,ostectomy or alloplastic
augmentation www.indiandentalacademy.com

Soft tissue asymmetry
Augmentation with bone grafts, alloplastic material and
silicone implants to re contour the desired areas of the
face
Muscular stripping

Thank you

Transient malocclusion

 Source: Angle Orthodontist on CD-ROM (Copyright © 1998 Angle Orthodontist, Inc.), 1995 No. 3, 233 -
239: Figures.
 Figure 4 Schematic picture of a face including reference plane A which is positioned between the bilateral
landmarks Exocanthion, while it is defined perpendicular in all directions to the line through these
landmarks.

Ajo 1991 Assessment of structural and displacement mandibular asymmetries - Schmid,
Mongini, and Felisio The following conclusions may be drawn:
 1. In the growing patient, craniomandibular asymmetry with transverse deviation of
the mandible and the chin, with no genetic or congenital origin and without a
history of trauma, infection, or tumor, is possibly the result of mandibular
displacement consequent to occlusal alterations.
 2. If the mandibular displacement is not detected and treated in a timely manner,
adaptive mandibular asymmetry may develop.
 3. Depending on the elapsed time between the onset of mandibular displacement
and the examination, the patient can show displacement asymmetry, structural
asymmetry, or a combination of both. The last possibility may be the most frequent
in a population of growing patients.
 4. The different patterns of asymmetry can be identified and to some extent
quantified in each patient.
 5. Successful treatment during the growing period is possible in some patients. If
the subject remains untreated, asymmetry can become a permanent feature in the
adult.
 6. However, mandibular displacement may not be all or even part of the cause of a
craniomandibular dysfunction. In such cases any kind of orthopedic treatment may
be completely or partially ineffective.
 7. Because the symmetry in one of the control subjects improved in the absence of
intervention, other factors besides treatment may be responsible for the different

Correction of arch asymmetries as suggested by
Lewis
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Management of deviated midline

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