Position of condyle in cl ii & iii /certified fixed orthodontic courses by Indian dental academy

POSITION OF CONDYLE IN THE
GLENOID FOSSA IN CLASS II &
CLASS III MO
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


Introduction
Orthodontists are constantly being challenged
with the task of providing their patients with
acceptable esthetics and masticatory function.
Although for the patient, esthetics is the immediate
and primary goal, function becomes far more
important
in
the
lifetime.
Developing
a
sound, functional masticatory system is the primary
goal of all orthodontic therapy.


Functional anatomy of the TMJ
The TMJ is a typical diarthrosis.
It is classified
anatomically as the gingilymoarthroidal joint which means
that the joint has relative sliding or gliding movement between
the bony surfaces in addition to the hinge movement common
to the diarthroidal joints. This is a synovial joint of the condylar
variety.
The joint consists of the upper and lower articular
surfaces.
The upper articular surface is formed by the
Articular eminence
Anterior part of the mandibular fossa

The inferior part of the articular fossa is formed by the
mandibular condyle.

The joint is divided into upper and lower parts by the
interarticular disc.
The articular fossa is on the inferior surface of the
squamous part of the temporal bone that forms a small part
of the floor of the middle cranial fossa.
The posterior limit of the joint is formed by the
squamotympanic fissure and the medial relation is the
petrotympanic fissure.


The disc is slightly thicker
medially than laterally.
LP, Lateral pole; MP. Media
pole
Articular disc, fossa, and condyle ( lateral view)

The mandibular condyle is basically ellipsoid connected
to the ramus of the mandible by a narrow bony isthmus or neck.
The condyle is longer lateromedially than in the other
dimensions. The average composite shape of the condyle has
a superior surface that is markedly convex from front to back
and gently convex from side to side.

The condyle is the portion of the mandible that
articulates with cranium, around which movement occurs.
From the anterior view it has a medial and a lateral
projection, called poles.
The medial pole is generally
more prominent than the lateral. From above, a line drawn
through the centres of the poles of the condyle will usually
extend medially and posterioly toward the anterior border
of the foramen magnum. The total mediolateral length of
the condyle is 15 to 20mm, and the anteroposterior with is
between 8 and 10mm. The actual articulating surface of
the condyle extends both anterior and posteriorly to the
most superior aspect of the condyle.


The posterior articulating surface is greater than the
anterior surface. The articulating surface is greater of the
condyle is quite convex anteroposterioly and only slightly
convex mediolaterally. The mandibular condyle articulates at
the base of the cranium with squamous portion of the temporal
bone is made up of a concave manibular, in which the condyle
is situated and which has also been called the articular or
glemoid fossa.


Inter articular disc or the meniscus
Is a fibrous connective tissue wafer filling most of the
space between the condylar head and the articular fossa and
dividing the joint cavities into 2 compartments. The disk itself
normally occupies only half of the joint space, with its
posterior attachments filling the posterior half. The disc and
its posterior attachments are generally referred to as the soft
tissue component of the TMJ.


Sagitally a biconcave structure, the thin portion in the
center serves as the articulating cushion between the
condyle and the articular eminence. The anterior border of
the disc is attached to the superior head of the lateral
pterygoid. As the condyle translates forward, the disk also
moves forward. So that the thin central part remains
between the articulating convexities of the condylar head
and the articular eminence. As the moves forward, the
tension is produced in the elastic portion of the posterior
attachment. This tension is thought to be responsible for the
smooth recoil of the disc posteriorly as the jaw closes.


According to Dr. Upton it shouldn’t be forgotten that
the disc also facilitates the gliding of the condyle along the
articular eminence, because of its slick surfaces.

Joint bony relationship
Joint space is the radiographic term for the cresent
shaped radiolucency between the bony structures of the
TMJ when the teeth are in occlusion. The soft tissue
structure of the joint projected as uniform radiolucency over
and around the condyle.
A comparison of the radiographic dimension of the
several portions of the joint space is often used by the
clinician as a guide by which the position of the condyle is
determined.


Condylar concentricity is the term for that condylar
position around which the anterior and posterior aspects of the
radiolucent joint space are uniform in width.
The condyle is said to be protruded when the posterior
joint space is larger.
The condyle is said to be retruded if the posterior joint
space is less than the anterior.


Normal posisiton of the condyle
• Williamson-Superior-anterior fossa position
• Stuart-Rearmost, midmost & uppermost position

of condyles in their respective fossae with the
mandible in the closed position

• The mandible should be able to close into

maximum intercuspation without deflecting the
condyles from their most ideal relationship in the
fossae

Centric Relation
• An idealized treatment goal
• CR of the mandible is a superior limit

position of the condyles in the fossae with
the mandible centered and its most closed
position


Inferior and superior
lateral pterygoid muscles

Function of the inferior lateral
pterygoid: protrusion of the mandible


Medial pterygoid muscle

Function: elevation of the mandible


Temporal muscle, AP, Anterior portion
MP – Middle portion, PP – Posterior portion

Temporal muscle, AP, Anterior portion
MP – Middle portion, PP – Posterior portion


Masseter muscle. DP, Deep portion:

Function: elevation of the mandible


Mandible, temporomandibular joint, and accessory ligaments


Muscles of mastication

A: Diagnostic muscle,

B-Function : depression of the mandible

Four movements of the mandible
Posterior opening border
Anterior opening border
Superior contact border
Functional movements
Posterior opening border – in slight opening of the
mouth there is rotational movement of the mandible with the
codyles in the terminal hinge position. This pute rotational
opening can occur until the anterior teeth are some 25 mm
apart. There is no translation of the condyle.


In the maximal opening of the mouth the
temporomandibular ligament tightens after there is an anterior
and inferior translation of the condylealong with the gliding of
the disc. Maximum opening is reached when the capsular
ligaments present further movement of the condyle. Maximal
opening is between 40 to 60mm when measured between the
Incisal edges of the maxillary and mandbular teeth.


With the mandible opened, the closure accompanied
by contraction of the inferior lateral pterygoid. Due to the
tightening of the ligaments there is posterior movement of the
condyle during closure. There is not a pure hinge movement
but there is some eccentricity during closure. The disc also
moves along.


Diagnosis
The diagnosis of the temporomandibular disorder
or the fit of the joint is very important to determine the
harmony of the stomatognathic system.
The diagnosis includes
Anscultation
Palpation
Functional analysis


Anscultation is done in the joint area to determine if
there is any creptius or clicking in the joint area.
Palpation includes the palpation of the joint which
also includes the palpation of the muscles to rule out the
possibility of any masticatory muscle tenderness.
The functional analysis includes the checking of the
various functional movements of the mandible.


It also includes the dental examination which will
determine the presence of the following due to the close
relationship of the joint and the occlusion. The dental
examination includes the
Occlusal and incisal wear
Restorations
Mobility of the teeth
Periodontal status of the teeth
Cross bite or scissor bite
Occlusion


Other diagnostic aids
Radiographic technique
Conventional radiography – TMJ is technically one of
the most difficult areas of the body to visualize well because
of multiple superimposition.
Transcranial projection – posterior auricular approach.
The central beam is projected across the cranium
through the petrous ridge of the temporal bone on the film
side and finally through the TMJ with the long axis of the
obliquely oriented condyle.

It is taken in both open mouth and centric occlusion.
To determine the bony relationship between the condyle and
the glenoid fossa when the mouth is closed and the degree
of anterior condylar movement as the mouth is opened.
It helps to detect,
The changes in the lateral aspect of the articulating
surface.
Position of the condyle in the fossa.


Disadvantage
Only the changes in the lateral aspect of the condylar
head can be seen.
Abnormal changes in the condylar neck is obsured by
the ipsilateral petrous ridge.
Stereoscopic transcranial projection-provides depth
prescription differentiating the multitude of the
superimposition bony shadows in this area.

Advantages
- The crest of the ipsilateral petrous ridge can be
dissociated from the condylar neck.

Infracranial projection – transpharyngeal or
Mc Queen projection
X ray film positioned against the side of the
patient head, parallel to the sagittal plane next to the TMJ of
the interest. The X ray tube head is placed on the skull
opposite the TMJ to be imaged.

Central beam through the tube side sigmoid notch
(window between the condylar and coronoid process) below
the base of the skull.
Open mouth view – move the condyle away from
dense superimposing base of the skull into a soft tissue
region, providing far from the greater radiographic contrast.

Enlarge the tube side window between the mandibular
notch and zygomatic process.


Disadvantage
In taken in closed mouth, the condylar head
superimposed by articular eminence.
Can be done only in the open mouth.
No diagnostic information about articular fossa of the
TMJ.

Uses
Gross visualization of the condylar process from
mandibular ramus to the condylar apex.
Diagnosis of the fracture of the condylar neck.


Transorbital view-Zimmer’s or transmaxillary view
Central beam passes throught the ipsilateral orbit and
through TMJ of interest.
Advantages
Lack of major superimposition over the most of the
condylar process.
Entire latero medial of convex articulating surface of the
condyle and the articular eminence.
Demonstration of the convex articulating surface of the
condyle and the slightly concave or flat, broad ridge of
the articular eminence.


Facial Projection
Panoramic View
With slight variations in the standard technique it can
provide screening of the condyles. To view the condyle best it
is often necessary for the patient to open the mouth
maximally so that the structures can be seen without any
superimposition on the condyle. Since the panoramic
radiograph is a transpharyngeal view the lateral pole of the
condyle becomes superimposed over the condylar head.
Therefore the area that appears to represent the superior sub
articular surface of the condyle is actually only the sub
articular surface of the medial pole.
Water view – with petrous ridge depressed, the
condylar and temporal surfaces of the TMJ may be seen by
clearly. Bulk of the inferior portion of the condyle will be
superimposed by the petrous part of the temporal bone.

Submentovertex
Reverse towne view unilateral or bilateral condylar
fracture superomedial displacement of the condylar
fragments.
Tomography these are true lateral projections.
Tomography used controlled movement of the head of the X
ray tube and the fill to obtain a radiograph of the desired
structure that deliberately blurs out other structures.


Advantages
More accurate than panoramic or transcranial
radiographic for identifying bony abnormalities or
changes.
Elevates the condylar position in the fossa more
accurately than in the transcranial view.
Disadvantages
Expensive
Inconvenient
Patient exposure to radiation increased
Uses
Lateral view of the cortical margin of TMJ.
Position of the condyle in the mandibular fossa.
Range of translatory movement.

Arthrography
On a conventional radiograph the image is formed as a
result of differential attenuation
Of an X ray beam passing through the structures. If the
structure lack density to attenuate the beam then they do not
appear on the radiograph. If the density of the structure is too low
or if the subject contrast is too low to meet the diagnostic records
the contrast and the density can be improved artificially.
Compounds of iodine are used for the contrast as the dye
material.
Water soluble compound are preferred in the joint
examination.
They supply information about the soft tissue structures of
the joint which is one of the major advantages of the technique.
The main contraindication is hypersensitivity reactions and
exacerbates the irritation of an already existing joint disease.

Uses
Displacement of the disc.
Herniation of the disc or loss of integrity of the
attachments.
Scarring and fibrosis of the joint.
Post operative evaluation.

Disadvantages
Invasive procedure.
Special training required.
Expensive.
High level of radiation.

Computerd tomography – was introduced in the year 1970.
CT scan provides a digital data measuring the extent of
X-ray transmission through an object. This numerical
information is transformed into a density scale and used to
generate or reconstruct an image.
The greatest advantage of the CT scan is that it images
of both soft tissue and hard tissue. This the condyle disc
relationship can be observed and evaluated without disturbing
the existing anatomy relationship.
For imaging the TMJ the GE system produces slices 1.5
mm thick in an axial, sagittal or coronal plane. The sagittal is
the best for the evaluation of the TMJ. The TMJ disc composed
of high density fibrous tissue will appear white on the CT scan.
Anteriorly dislocated disc is seen as a whiter projection anterior
to the condyle in the closed mouth view.

Disadvantages
Increased radiation exposure.

Equipment very expensive.
Time consuming and expensive
procedure.
Do not offer benefits of dynamic joint
movements.

TMJ Video Tape (Angle Orthodontist, 1988 No. 2, 101 104: TMJ Diagnosis and Treatment in a Multidisciplinary
Environment – a follow-up study. Michael C. Alpern,
Douglas)
Video tape provides an effective method of
patient/parent education and informed consent. This video
tape assists in education the patient in what TMJ pathology
is, what its causes are (heredity, stress, and function)
(GLLB 1977), and introduces the idea that if a patient
comes to an orthodontist with a hereditary or
developmental or congenital problem of bad bite of the
teeth or jaws, this problem also could involve the
temporomandibular joint. In other worlds, not everyone is
born with a perfect temporomandibular joint.

Any joint can be subject to a hereditary predisposition
toward joint disease; everyone is familiar with these variations
in the joints of the extremities and the spine, and the TMJ is not
immune. Finally, joints are subjected to the stresses of life, and
the TMJ is especially vulnerable to physical stress arising from
the emotional stresses of our society. Such stress can be a
direct cause of the patient chronically cracking or moving the
jaw or excessively using and abusing the jaw or teeth.


The video tape is repetitive, using a series of
vignettes, and tends to say the same thing that the
orthodontist wants to tell the patient. The patient begins to
understand that, as the orthodontist approaches the bite

problem, he is not just going to be moving teeth around. He
is, instead, going to be approaching the total facial problem
from the incisal edges of the teeth to and including the

temporomandibular joints, the airway, and the swallowing
mechanism.


The patient is informed initially that because of their
TMJ problem, treatment must be multidisciplinary. Altering
heredity is impossible, but can alter stress and function.
Stress will be approached by a psychological
examination. The patient will be referred to a competent TMJ
team psychologist for testing with an MMPI (Minnesota
Multiphasic Personality Inventory) as well as other
psychological evaluations. The patient and/or parents will be
informed of the level of stress that the patient is under and
appropriate recommendations for stress counseling and
therapy will be made if indicated. The patient is also give a
score of 1 through 5 using the Wharton psychological rating
scale.

The patient is told that if there is headache or head

pain not directly associated with the temporomandibular joint,
that the orthodontist may refer them for examination by a
competent board-certified neurologist to identify or rule out

any neurological problems.

The patient is informed that in addition to complete

orthodontic diagnostic records, the orthodontist may find it
necessary to prescribe direct parasagittal CT or MRI scans to
evaluate pathology in the temporomandibular joints.

Finally, the patient is told that orthodontic therapy may
include some form of splint therapy. With splint therapy, there
are three things that can happen:

The patient’s temporomandibular joint dysfunction will
improve and continue to improve, and no other
treatment
will be needed.
The TMJ symptoms will continue and at or nearing the
end
of orthodontic therapy, temporomandibular joint
arthroscopic surgery may be necessary.
A crisis may be precipitated in the temporomandibular
joint.
Arthroscopic surgery may be required, followed by
continued splint therapy.

Magnetic Resonance Imaging
MRI has emerged as the prime diagnostic modality for
imaging assessment of patients with suspected internal
derangement had soft tissue abnormalities of the TMJ. This is
the result of the surface coil hat allows high quality imaging of
superficially located parts of the musculoskeletal system.
MRI provides an image of both the soft tissue and hard
tissue components of the joint and its surrounding structure.
There is no radiation.
No harmful biological effects.
MRI can be achieved in multi plane which is a significant
advantage for the detection of medial and lateral
displacements of the TMJ.

Absolute contra indication
Cerebral Aneurysms
Cardiac pace makers

Relative contraindication
Uncooperative patients
Pregnant women
With metallic prosthetic heart valves
Femo magnetic foreign bodies


Thermography
Electronic thermography has shown promise as an
objective tool for assessing TMJ disorders. It is a tool for
selecting normal subjects from subjects with TMD symptoms.
Thermography can measure the skin surface temperature
overlying TMJ with an accuracy of 0.1ºc. Thermography has
been recently applied to the assessment of TMD.


CEPHALOMETRIC KEYS TO INTERNAL DERANGEMENT OF
TEMPOROMANDIBULAR JOINT SOUNDS AND CONDYLE /
DISK RELATIONS ON MAGNETICREASONANCE IMAGES

AJO (101) : 70-8; 1992 (Sug Joon Ahn, Woo Kin and
Dond Seok Natim)
Sug –Joon Ahn et al (2004) determined the
association between the progression of internal derangement
and the alterations in dento facial morphology in women with
Class II malocclusion by analyzing routine lateral
cephalograms.
Lower
facial
height
and
ramus
height, backward rotation of ramus and mandible and relative
protrusion of upper and lower lips were found in patients with
internal derangement of the TMJ.


backward rotation of ramus and mandible and
relative protrusion of upper and lower lips were
found in patients with internal derangement of the
TMJ.
These changes became increasingly severe as
internal
derangement
progressed
to
disc
displacement without reduction (DDNR) via disc
displacement with reduction (DDR).


COMPUTED TOMOGRAPHY EVALUATION OF
TEMPOROMANDIBULAR JOINT ALTERATIONS IN

PATIENTS WITH CLASS II DIVISION 1
SUBDIVISION MALOCCLUSIONS: CONDYLEFOSSA RELATIONSHIP AJO 126:48-52; 2004.

( Robert Willer Farinazzo Vitral, Carlos de Souza
Telles, Marcelo Reis Fraga, Robert Sotto Major Fortes
de Oliveira, Orlando Motohiro Tanaka)
Robert Willer Farinazzo Vitral et al (2004)
assessed the depth of the mandibular fossa angulation of


the articular tubercle, condyle-fossa
relationship and the concentric position of the
condyles in persons with Class II Division 1
malocclusions using computed tomography (CT).
They concluded that it is feature of Class II
malocclusion to exhibit more anteriorly placed
condyles.


The treatment prognosis for class II
malocclusion depends on the analysis of
relationship and the determination of path

of closure.


In the malocclusions without functional
disturbance the path of closure from rest to
occlusion is straight up and forward, with a hinge
movement of the condyle in the fossa. These
are true Class II malocclusions

Hinge movement from the rest (A) to occlusal (B) position in a functionally
correct Class II relationship with a normal path of closure.

In Class II malocclusions with
functional disturbances a rotary
action of the condyle in the fossa
from postural rest to occlusion is
evident. From initial contact to full
occlusion, condylar action is both
rotary and translatory up and
backward (posterior shift). Thus the
movement combines rotary and
sliding components as Boman
(1952) and Blume (1952) showed in
their research, this type of activity is
the most common, particularly in
cases of excessive overbite. This
functional
type
of
Class
II
malocclusion appears more severe
than it actually is sagittally


In Class II malocclusions with
functional disturbances in which the
path of closure is up and forward from
rest to initial contact (usually in the
molar region), the mandible may be
anteriorly displaced from initial contact
as the cusps guide the mandible into a
forward position, with translatory
movement of the condyle down and
forward on the posterior slope of the
articular eminence.
The path of
closure appears more up and forward
than it is without tooth interference.
This condition has been illustrated by
Woodside
(1984) in his research.
This malocclusion is more severe than
it appears with the teeth in occlusion.
However, this variation of path of
closure is least frequent for Class II
malocclusions

Temporomandibular joint growth changes in
hyperdivergent and hypodivergent Herbst subjects. A
long-term roentgenographic cephalometric study
- Hans Pancherz, AMJ

The aim of this long-term study was to assess the
amount
and
direction
glenoid
fossa
displacement,
condylar
growth,
and
“effecive”
temporomandibular joint (TMJ) changes in 3 vertical
facial-type groups of Class II Division 1 malocclusions
treated with the Herbst appliance.


Glenoid fossa displacement
During normal growth, the glenoid fossa is displaced
in a posterior-inferior direction. During Herbst treatment
the fossa in all groups was displaced in an anterior and
inferior direction. This was most likely the result of
remodeling processes at the posterior fossa wall.


Condylar growth
In
untreated
subjects
having
different vertical facial morphologies, Bjork
and Skieller demonstrated a vertical condylar
growth pattern (predominantly superiordirected condylar growth) in hypodivergent
subjects and a sagittal condylar growth
pattern
(predominantly
posterior-directed
condylar growth) in hyperdivergent subjects.


Conclusion
The amount and direction of TMJ grouth changes (fossa
displacement, condylar growth, and “effective” TMJ changes) were
only tmporarily affected favorably in the sagittal direction by Herbst
treatment. For glenoid fossa displacement changes, no differences
existed between hypodivergent and hyperdivergent subjects t any
examination period. But condylar growth and “effective” TMJ
changes, on the other hand, were directed more posteriorly in
hyperdivergent than in hypodivergent Herbst subjects during
treatment and post treatment.


Roth (1970) described that in certain
malocclusions it is difficult to achieve a satisfactory
functional result. These could range from simple dental
problems like tooth size discrepancy, crowding, poor tooth
structure etc. to severe skeletal problems like severe
Class II / III situations and facial asymmetry cases. An
unstable occlusion produces joint compression during
interdigitaion.
Coexisting remodeling stimuli (Para
functional habits, macrotrauma, systemic diseases) may
accentuate condylar remodeling producing dysfunction.
Articular disc displacement may be a sign of dysfunctional
remodeling.


However,
these
changes
may
remain
asymptomatic depending on the patient’s tolerance
level and adaptive capacity. As the adaptive capacity
reduces with age, psychological stress may dominate
and precipitate symptoms.


RICKETTS (1953) conducted a radiographic study of
180 pathologic TMJ cases and observed that four distinct
types of traumatic joint disturbances seemed to stem from
four different types of clinical malocclusions. These were
described as follows :

TYPE 1
Abnormal overjet characterized by the typical Class
II, division 1 relationship.
Such patients move their mandibles forward in
compensation for the protruding teeth during incision and
speech, but the condyle usually is drawn backward to a
normal position in the fossa during forced closure.

Ricketts did observe some patients who
sustained this forward postured position even during
closure of the teeth. This abnormal range of function was
felt to stress the joint and result in joint trauma.

TYPE 2.
This is identified as true distal or posterior
displacement, characterized by the typical class II division 2
patient. As the condyle is displaced distally, it is said to
lodge behind the bulbous portion of the articular
disc, resulting in clicking on opening as it moves onto the
disc and closing as it slips off the disc.

TYPE 3
is related to bicuspid and molar interferences.
Balancing side interferences represent the classic example
of this phenomenon. Other examples are seen in cases
with extruded molars (i.e 3rd molars) and posterior cross
bite.

TYPE 4
is represented by cases with a loss of posterior
support, as occurs with loss of posterior teeth. This is said
to allow the condyles to seat more superiorly in the
joints, so the joints receive stresses that should normally be
borne by the teeth.

• Since that original study, RICKETTS(1983) has observed

other types of conditions that were associated with
concurrent TMJ pathologies and categorized these into
the following aquired occlusal functional disorders;

•
•
•
•
•
•
•
•

Loss of posterior support
Abnormal levering against the joints
Distal displacvement of the condyle
Interferences of the teeth
Mandibular eccentricity
Third molar effects
Failure of long term growth prediction
Post-surgical complications


Although this list of factors serves as
an excellent starting point for further evaluation and
better understanding of the relationship between
malocclusion and joint pathology, there appear to be
areas of overlap among the categories.
For
example, third molar effect is also a form of abnormal
levering againstthe joint, a category which has also been
extensively described by ROTH (1970). A failure of longterm growth prediction can result in distal condyle
displacement and could therefore be considered a
subcategory of distal displacement


• Finally interferences of teeth may be found in all over the
other seven categories, and categories 1 through 5 are
frequently seen as results of postsurgical complications.

• The above categories do not relate speciafically to the
diagnosis and treatment of orthodontic patients.
Such
diagnosis and treatment is usually related to the vertical (high
angel versus low angle), the horizontal (Class III versus Class
II), and the lateral (functional side shift versus true skeletal
asymmetry) discrepancies. Hence, the following developed
by the author may be more appromitely utilized the
evaluation of the skeletal and dental component of TMJ
dysfunction


• Vertical Discrepancy
Lack of posterior support
Molar or bicuspid fulcruming

• Horizontal Discrepancy
Anterior skids or anterior posturing
Distal displacement

• Lateral Discrepancy
Functional side shift
True vertical asymmetry
These categories reflect disharmony in centric
position, and when supplemented with the eccentric
disharmonies of lateral and postrusive interferences provide an
overall perspective of the extra-articular skeletal and dental
components of TMJ dysfunction

AJO-DO1987 Preventing adverse effects on TMJ through orthodontic
treatment Wyatt
In the Class II malocclusions with deep interlocking cusps
headgear and/or Class II elastics are often used in an effort to get the
patient into a Class I cuspal relationship. As the maxilla is moved
backward, the muscles of mastication will attempt to retract the mandible
when the patient closes into maximum intercuspation. This compensating
movement by the mandible can put distal pressure on the condyles and
conceivable cause an anterior dislocation of the disk.

To correct this problem in orthodontic
treatment , a possible solution is a flat palen of acrylic, which can be
bonded on the occlusal surfaces of the lower molars and premolars after
the fixed appliance has been placed.

• When

cusps get past a “point-to-point”
contact, the flat oclusal acrylic plate is removed.
Now the cuspal inclines tend to move the
mandible forward and the maxilla backward on
maximum closure.
This ,may aid in the
retraction of the maxilla, but since the mandible
moves forward, one could assume it might also
alleviate TMJ problems.


CORRELATIONS BETWEEN CONDYLAR

CHARACTERISTICS AND FACIAL MORPHOLOGY IN
CLASS II PREADOLESCENT PATIENTS
AJO 114(3):328-336; 1998. (Gail Burke, Paul
Major, Kenneth Glover, Narashimha Prasad)
Most Class II, division 1 patients exhibit distraction of the
condyle during various functions. This sustained forward
posture position could lead to abnormal stresses and trauma
in the joint. This joint trauma is accentuated in high angle
cases-which manifest as decreased disk spaces with
posteriorly angled condyles in a tomographic assessment by
Burke and co-workers. This increased prevalence of internal
derangements in class II high angle cases has lead us to
select these cases for CT assessment of the
temporomandibular joint.

Correlations Between Condylar Characteristics and
Facial morphology in Class II preadolescent
patients
336;1998

- Gail Burke, Paul Major, Kenneth Glover,
Narashimha Prasad, AJO, 114(3):328-

Gail Burke et al (1998) determined
correlations between condylar characteristics measured
from preorthodontic tomograms of preadelescents and
their facial morphologic chaacteristics. They concluded
that patients with vertical facial morphologic
characteristics displayed decreased superior joint spaces
and posteriorly angled condyles which could be due to
remodeling and degenerative changes of the disc with
thinning of the posterior band.

Cephalometric keys to internal derangement of
temporomandibular joint in women with class ii
malocclusion
- Sug Joon Ahn, Woo Kin and Dond Seok Natim,
AJO,486-495;2004

Sug –Joon Ahn et al (2004) determined the
association between the progression of internal
derangement and the alterations in dento facial
morphology in women with Class II malocclusion by
analyzing routine lateral cephalograms. Lower facial
height and ramus height, backward rotation of ramus and
mandible and relative protrusion of upper and lower lips
were found in patients with internal derangement of the
TMJ.

These
changes
became
increasingly
severe
as
internal
derangement progressed to disc
displacement without reduction (DDNR)
via disc displacement with reduction
(DDR).


CLINICAL EXPERIENCE WITH MRI IN INTERNAL
DERANGEMENTS OF THE TMJ
AO (1) : 21-32; 1988 (Raphael T Schach, Lionel Sadowsky
P)
Rapheal T Schach et al (1988) evaluated MRI images of
50 symptomatic temporomandibular joints in twenty six
individuals. They concluded that MRI diagnosis of disc /
condyle relationship was satisfactory in 89.5% of the cases
as compared to arthrography.


TMD STATUS OF JUVENILE PATIENTS
AJO (101) : 54-9; 1992
(Hans, Liberman, Gold Berg, Rozencweig and Bellon)

Hans
et
al
(1992)
compared
clinical
examination, history and MRI for identifying TMJ
disorders in orthodontic patients who presented with
primary compliant of malocclusion. MRI was selected
for use because of its high specificity for identification of
abnormal condyle-disk relationships. They concluded
that thorough history and clinical examination are the
diagnostic tests of choice because they identify
potential temporomandibular disorders.

AJO (101): 88-96; 1992
(Sakuda, Tanne, Tanaka and Takasugi)
Sakuda et al (1992) utilized polytomography, which
takes hypocycloidal motion (POLYTONE-U, Philips Co.
Ltd., The Netherlands) to evaluate a three dimensional
position of the condyle relative to the glenoid fossa in the
TMJ space and to investigate the accuracy of the method.
In addition, clinical application of this technique was
attempted to elucidate its availability for diagnosis of
TMD before orthodontic treatment.


TEMPOROMANDIBULAR JOINT SOUNDS AND
CONDYLE / DISK RELATIONS ON
MAGNETIC RESONANCE IMAGES
AJO (101): 70-8; 1992 (Sutton, Sadowsky,
Bernreuter, Mccutcheon & Lakshminarayanan)
Sutton et al (1992) compared the condyle / disk
relationsthip on magnetic resonance images (MRI’s) in a
group of subjects with completely silent TMJ when tested
clinically with those in subjects with readily discernible TMJ
sounds. Of the silent joints, 89% were found to have
sounds when tested with accelerometer.


MRI scanning was used to determine the
relationship of the disk to the head of condyle, the
relationship of condyle / disk complex to the slope of
the eminence. They concluded that the clinically
discernable joint sound group had a change in the
condyle / disk position in the image immediately after
the position of the joint sounds.


PREVALENCE OF TMJ DISC DISPLACEMENT
IN A PRE ORTHODONTIC ADOLESCENT
SAMPLE
AO (70) 6: 454-463; 2000 (Nebbe B, Major PW)
Nebbe B et al (2000) evaluated the prevalence of the
TMJ disc displacement in 194 preadolescents by means of
MRI. Unilateral and bilateral normal disc position was
more prevalent in boys compared to girls. All forms of
anterior, rotationally and medial disc displacement were
more prevalent in the female sample.


OBSERVATION OF THREE CASES OF TEMPOROMANDIBULAR JOINT OSTEOARTHRITIS AND
MANDIBULAR MORPHOLOGY DURING
ADOLESCENCE USING HELICAL CT, J ORAL
REHABIL 31.(4):298-305; 2004
(Yamada K, Saito I, Hanada K, Hayashi T)
Yamada et al (2004) used helical computed tomography and
ceogalometry to analyse relationships between the pattern and
location of condylar remodeling and the changes in craniofacial
morghology in three patients with temporomandibular joint
osteoarthritis and found that the mandible usually rotates
posteriorly, resulting in an unsatisfactory profile, especially in
patients with pre-treatment mandibular retrusion

CONDYLAR BONY CHANGE AND CRANIOFACIAL
MORPHOLOGY IN ORTHODONTIC PATIENTS

WITH TEMPOROMANDICULAR DISORDERS (TMD)
SYMPTOMS : A PILOT STUDY USING HELICAL
COMPUTED TOMOGRAPHY AND MAGNETIC

RESONANCE IMAGING CLIN ORTHOD RES.2(3) :
133-42 ; 1999 Yamad K, Hiruma Y, Hanada K,
Hayashi T, Koyama J, Ito J
Yamada et al (1999) investigated how condylar bony
changes relate to craniofacial morphology using helical
CT and MRI in 29 orthodontic patients.

Craniofacial morphology of orthodontic
patients with condylar bony changes was compared
with Japanese standard. Disk displacement without
reduction was seen in 90.6% of the bilateral group, and
in 76.9% of the unilateral group.
Retrognathic
mandibles were shown in the bilateral group. All
subjects exhibited a lateral shift of the menton toward
the condylar bony changed side in the unilateral group.
They concluded that condylar body changes may be
related to a lateral shift of the mandible and a
retrognatic mandible in orthodontic patients with TMD
symptoms.


Hinge-type condylar function is often associated with
Class III malocclusions with straight paths of closure. If the path
of closure is up and back (an anterior postural rest position), the
prognosis is even poorer. In Class III malocclusions with anterior
displacement that creates an up and forward path of closure with
combined rotary and translatory action of the condyle from
postural rest to habitual occlusion, the prognosis is much better
and treatment success is possible, even in the permanent dentition.

A: Anterior rest position in a severe Class III malocclusions
B: Posterior rest position in a forced bite type of Class III malocclusion

In cases of class III, the condyle that is
forwardly placed has a good prognosis, and the
condyle that is posteriorly placed has a better
prognosis.
The wear of the functional appliances
causes a remodeling of a glenoid fossa. Both the
removable and fixed functional appliances are
known to have remodeling effect on the glenoid
fossa.

Chin cup therapy


• The effects on chin cup therapy on the TMJ are as
follows (1988, AJO, Tosho et al)

• Forward bending of the condylar neck
• Enlargement of the joint cavity

• Closing of the angle of the mandible
• Force distribution on the lateral surface of the
temporal bone may affect the size and position of
the craniofacial structures.


Sometimes a skeletal Class III relationship is partially
compensated by labial tipping of the maxillary incisors and lingual
tipping of the mandibular incisors. Because of the extreme tipping
possible, an anterior sliding movement into occlusion can occur.
Uprighting the incisors into their proper axial inclinations results in a
severe Class III sagittal tooth relationship. Treatment of this type
of malocclusion by orthodontic means is difficult because
dentoalveolar compensation is not possible; the incisors are already
overcompensated before treatment. Orthognathic surgery should
be considered and discussed with the patient. This type of
malocclusion is referred to as a pseudo-forced bite or displacement


Magnetic Resonance Imaging assessment of the
positional relationship between the disk and
condyle in asymptomatic young adult mandibular
prognathism: AO 73:550-555; 2003

Hatice Gokalp (2003) studied the disk position
relative to condyle and condylar position relative to
glenoid fossa in clinically asymptomatic and
orthodontically untreated young adult Class III
patients by MRI.
They concluded that clinically
asymptomatic Class III patients may be candidates for
TMJ derangements and the anterior positioning of the
articular disk could be due to anterior pull of the
superior lateral pterygoid

Midline switch / cross
elastics
Midline switch or cross elastics have a
more subtle effect. As the jaw is pulled to one
side, distal pressure is put on one condyle only.
If this creates a TMJ problem, midline elastics
should be worn only during waking hours so
that muscle can help to hold the mandible
forward.


RPHG and Class III
elastics
RPHG and Class III elastics produce a distal
driving force of the mandible and condyle. This would
produce a reciprocal forward displacement of the disc
and pressure on retrodiscal tissues.
• It is better to have the patient wear lower or reverse headgear and
Class III elastics only during waking hours.
• Muscle tone (tension) positions the mandible forward.
• When worn at night, the muscles are relaxed and there is more distal
pressure on the condyle because compensating muscle activity is not
in play.


Treatment effects of Frankel functional
regulator III in children with Class III
malocclusions
- Hyoung
S.Baik, AJO, 2004

The purpose of this study was to evaluate the
skeletal and dental effects produced by the Frankel
functional regulator III appliance in growing children
with Class III malocclusions.
The treatment efects found were mainly from
backward and dwonward rotation of the mandible
and linguoversion of the mandibular incisors.


TMDs


Definition
Temporomandibular disorders (TMDs) are defined as
“either functional or anatomic damage to the joint, leading to
uncoordinated condyle-fossa relationships in static and dynamic
phases or alterations in the spatial positions of the mandible.
The etiology of TMDs is complex and multifactorial
The etiologic classification as given by Roth in the year
1980, Jco is given below along with the exacerbating features
as given by Bishara
Systemic

(Wyatt, 1987, AJO)

Acquired


Cluster of related disorders in the stomatognathic system Perpetuating
factors (Samir E. bishara)
Behaviroal factors
Social factors
Emotional factors
Congnitive factors
Etiology of the TMD, as given in Angle Orthodontist, Inc.), 1988 :
Malocclusion and the Temporomandibular Joint – An Historical Perspective
Richard P.McLaughlin.

The relationship between dental malocclusion
and TMJ
dysfunction has been discussed in dentistry for over sixty years.
Historically, the greatest emphasis has been placed on malocclusion as
the primary etiologic factor in TMJ dysfunction. More recently, while
malocclusion has continued to be accepted as an important element in
many of these problems, other conditions have also been recognized as
important etiologic factors.

The challenge for dentistry today is to differently
diagnose patients who present with TMJ dysfunction. It is
essential to look beyond the occlusion to identify all of the
etiologic factors that may be involved, and then establish the
extent to which each contributes to the problem

COSTEN (1934) contended that loss of vertical

dimension leads to compression of the joint structures, causing
symptoms of pain and dysfunction within the temporomandibular
joints. He recommended bite opening procedures to correct the
problem.

SCHUYLER (1935) contended that occlusal
disharmony, and not a “closed bite” was the chief
cause of TMJ problems.
He rejected Costen’s
hypothesis, and recommended correction of occlusal
disharmony for the treatment TMJ pain and
dysfunction.

SICHER (1949), an anatomist, presented
studies on the functional anatomy and biomechanics of the
temporomandibular joint. Sicher contended that it was
anatomically impossible for Costen’s proposed theory to be
correct, and shortly thereafter “Costen’s Syndrome” was
rejected by the profession.
In
1956,
SCHWARTZ
discussed
the
importance of the musculature relative to TMJ disorders, and
introduced the “Myofascial Pain Dysfunction (MPD)
Syndrome”. He contended that occlusal disharmony led to
muscle dysfunction in many patients and this in turn was
responsible for subsequent pain and damage to the
temporomandibular joints.

Internal Derangement
The term “internal derangement” (ID)
is defined as an abnormal positional and
functional
relationship
between
the
disk, mandibular condyle and the articulating
surface of the temporal bone, resulting in soft
tissue interference of joint function. The most
common
abnormality
encountered
when
imaging patients of TMDs is different forms of
disk displacement. Disk displacement can occur
in any anatomic direction

Cephalometric keys to internal derangement of
temporomandibular joint in women with Class II
malocclusions
-Sug-Joon Ahn, AJO,Oct,2004
The aim of this study was to find cephalometric keys to provide
imformation on the progression of tempromandibular internal
derangement. The sample consisted of 58 women with Class II
malocclusions.
They were examined with routine lateral
cephalograms and magnetic resonance imaging of the
temporomandibular joint (TMJ) before orthodontic treatment. They
were classified into 3 groups according to the results of the
magnetic reasonance imaging: normal disk position, disk
displacement with reduction and disk displacement without
reduction.

INTERNAL DERANGEMENT OF TEMPORO- MANDIBULAR JOINT
- Isberg, Widmalm and Ivarsson, AJO 453-460;

1985
Isberg et al (1985) examined fifteen patients with
internal derangement of the temporomandibular joint
(TMJ) clinically and radiographically. Electromyographic
activity of temporails and masseter muscles were also
assessed. All the patients with internal derangement
demonstrated interferences on the ipsilateral side. This
was interpreted as the result of the disc displacement
producing a reduced joint space and, consequently, a
decreased verticaldimension on the symptomatic side.

In
association
with
disc
displacement, electromyographic activity of the temporalis
and masseter muscles occurred when the condyle slid over
the posterior band of the disc and could be interpreted as
an arthrokinetic reflex caused by distraction. Anterior disc
displacement without reduction (closed lock) could cause
spastic activity in the temporalis muscle on the affected
side. Spastic activity of the masseter and temporalis
muscles occurring on the same side as a joint with anterior
disc displacement hinders or inhibits the condylar
movement necessary to achieve reduction.


Skeletal and dental patterns in patients with
alterations of TMJ,
- Stringent AND Worms, AJO:285-297;1986

Stringent et al (1986) examined skeletal and
dental characteristics of subjects with documented
internal derangements of the TMJ and compared these
characteristics to those of a matched control group.
Specific attention was given to skeletal variations in the
anteroposterior and vertical planes as well as overbite
and overjet. Cephalometrically, there was a tendency of
hyperdivergency,
increased
horizontal
skeletal
discrepancy and no difference in the angular
relationships of the anterior teeth in each arch to their
respective skeletal bases.

Internal
Derangement
of
The
TMJ-changes
associated
with mandibular repositioning and orthodontic
therapy,
- Stephen D Keeling, Charles Gibbs, Matthew B Hall,
Stephon Lupkiewics

Stephon Keeling et al (1989) assessed the
chronic painful internal derangement of patients using
transcranial
radiographs,
arthrograms,
lateral
cephalometric radiographs and recordings of mandibular
movements. The patients were treated with anterior
positioning splint therapy and orthodontic treatment.
Post treatment findings revealed a decrease in ANB,
more anterior positioning of the mandible and more
confined sagittal envelope of motion in Posselt’s diagram

TMJ and craniomandibular disorders
-Paesani, westesson, Hatala, and tallents:
AJO,(101):41-47’1992

Paesani et al (1992) determined the prevalence of
temporomandibular joint internal derangement in
patients with signs and symptoms of craniomandibular
disorders, bilateral imaging was performed in a
consecutive series of 115 patients with signs and
symptoms of craniomandibular disorders.
The TMJ
arthrography was performed bilaterally on 51
patients, and magnetic resonance imaging (MRI) was
performed bilaterally on 64 patients. 78 % had different
stages of unilateral or bilateral internal derangements.
The study indicates that almost 80% of patients with
signs and symptoms of craniomandibular disorders have
different forms of internal derangement.

Pediatric TMJ Derangement: Effect on Facial
Development,
- Schellhas, Pollei and Wilkes: AJO:51-59;1993

Schellhas et al (1993) evaluated the
relationship between internal derangement of TMJ and
disturbed facial skeletal growth (dysmorphogenesis) in
128 children aged fourteen years or younger using
combined radiographic & MR imaging studies of both
TMJs. Of 60 retrognathic patients, 56 were found to
have TMJ derangement, generally bilateral and often of
advanced stage. In cases of lower facial asymmetry, the
chin was uniformly deviated towards more degenerated
TMJ.
They concluded that TMJ derangements are
common in children and may contribute to development
of retrognathia with or without asymmetry.

Relationship between TMJ disk displacement
and skeletal facial form
- Brand, Nielson, Tallents, Nanda, Currier, and Owen,
AJO 121-128;1995

Brand et al (1995) compared skeletal and
dental relationships in a group of twenty four females
with clinical evidence of internal derangements and a
group of twenty three females with evidence of
normal disk position using magnetic resonance
imaging and cephalometric radiography, and
concluded that patients with ID had significantly
smaller lengths of maxillary and mandibular bodies.


Subluxation
Subluxation of the TMJ represents a sudden
fowrard movement of the condyle during the
latter face of mouth opening.
When the
condyle moves beyong the crest of the
eminence, it appears to jump forward to the
wide open position.
This occurs because the steep eminence
requires a great deal of rotational movement of
the disc on the condyle when the condyle
translates out of the fossa.

Spontaneous dislocations
Spontaneousl dislocation represents a hyperextension of the TMJ
resulting in a condition that fixes the joint in the open
position, preventing any translation. This condition is clinically referred to
as an open lock because the patient cannot close the mouth. Like
subluxation, it can occur in any joint that is forced open beyond the
normal restrictions provided by the ligaments.
When the condyle is in the full forward translatory position, the disc
is rotated to its fullest posterior extent on the condyle and firm contact
exists between it. The condyle, and the articular eminence. In this
position the strong retracting force of the superior retrodiscal
lamina, along with the lack of activity of the superior lateral
pterygoid, prevents the disc from being anteriorly displaced. The
superior lateral pterygoid normally does not become active until the turn
around phase of the closing cycle

Clinical features of TMD
Clicking:
• Always reciprocal.

• A product of the anatomical shape of the disc and its stereoscopic
relationship of the head of the condyle at the beginning of the opening
movement.

• 2 are heard-one on mouth opening and the other at the same point on
mouth closing.

• Opening click is loud and audible; closing click may or may not be
audible.

• Due to continuous abuse of the ligaments, the disc may be pushed ahead
of the condyle during the entire course anterior recess of the capsule
becomes distorted and enlarged to accommodate the conglomeration of
the discal and associated ligamentous tissues referred to as “balled-up
disk”. It represents a disc that is perpetually jammed ahead of the
translating condyle, thus limiting the range of translocation itself. This
condition is referred to as “clinical closed-lock”.

Crepitus:

• Sound of denued bone on bone.
• Chronic abuse of the disc by superior posterior
displacement of condyle can cause perspiration of the
disc.

• The noise of the crepisus results from contact of the
head of the condyle with either the dome or slope of the
articular eminence without any intervening shock
absorbing disc due to perforstation.

• Creptus is always a sign of long standing and severe
posteriosuperior displacement of the condyle and an
advanced level of intra-articular degeneration.

Axiography
The most valuable use of axiography is in
the early detection of subclinical discopathies
and factors capable of causing dysfunction.
It provides data necessary to substantiate
other clinical findings and to make a differential
diagnosis temporomandibular joint pathology
By comparing hinge-axis pathways of
patients with dysfunctions with those of healthy
patients without dysfunctions it is possible to
develop a classification differential diagnosis

Rotation of the jaw bases


Base plane angle and inclination angle
are used to evaluate the rotation of the upper
and lower jaw bases. These rotations are of
special interest in treatment with functional
appliances because they show whether such
appliances are indicated and provide the criteria
for appliance construction.


The rotation of the mandible is
growth conditioned and depends on the
direction and mutual relations of growth in
crements in the posterior and anterior facial
skeleton. If condylar growth proceeds at a
greater rate, horizontal rotation results. If
growth increments are balanced, paralled
growth down the Y-axis occurs.


Bjork (1962) differentiates the two processes
involved in rotational growth of the mandible.
Remodeling of the mandible in the symphyeal and
gonial areas – this remodeling is called matrix and often results in
subsequent rotation. More apposition in the gonial area and
resorption in the symphyseal area lead to horizontal rotation.
Greater apposition in the symphseal area and resorption in the
gonial area causes vertical rotation.
Vertical or horizontal rotation of the mandible in its
neuromuscular envelope – This rotation is called matrix
rotation, or relocation of the functional matrix, according to Moss
and Enlow (1962). Rotation observed cephalometrically is called
total rotation, it consists of both intermatrix and matrix rotation.


The following types
of rotations can be
differentiated, as shown
by Laverangne
and
Gasson (1982) in human
implant studies:
Covergent rotation of
the jaw bases – This

rotation
creates
a
severe, deep overbite
that is difficult to man
age
using
functional
methods.


Divergent rotation of the jaw
bases
This rotation can cause
marked
open-bite
problems.
In severe
cases,orthognathic surgery
is required for correction


Cranial rotation of both bases
In this horizontal
growth
pattern
a
relatively
harmonious
rotation of both jaws
occurs in an upqard and
forward direction. This
rotation of the maxilla
compensates for upward
and forward mandibular
rotation, offsetting a deep
bite.
The result is a
normal overbite

Caudal, or down and back, rotation of
both bases
This
rotation
occurs in a relatively
harmonious manner.
The down and back
maxillary
rotation
offsets the open bite
created by down and
back
mandibular
rotation.

Importance of condyle in orthognathic
surgery
All procedures, however, that involve
movement of the entire maxilla or mandible
must
have
some
influence
on
the
temporomandibular
joints.
Segmental
osteotomies may also influence the occlusion so
that TMJ function is altered


Open-bite with the condyle seated

Proper positioning of the condyles during
surgery by autorotating the maxilla and
mandible wired together permits recognition
of posterior bony contact . Note that the
direction of finger pressure is upward and
forward


Thank you


INTERNAL DERANGEMENT OF TEMPORO- MANDIBULAR JOINT
AJO 453-460; 1985 (Isberg, Widmalm and Ivarsson)
Isberg et al (1985) examined fifteen patients with internal
derangement of the temporomandibular joint (TMJ) clinically
and radiographically. Electromyographic activity of temporails
and masseter muscles were also assessed. All the patients
with internal derangement demonstrated interferences on the
ipsilateral side. This was interpreted as the result of the disc
displacement
producing
a
reduced
joint
space
and, consequently, a decreased verticaldimension on the
symptomatic side.

In
association
with
disc
displacement,
electromyographic activity of the temporalis and masseter
muscles occurred when the condyle slid over the posterior
band of the disc and could be interpreted as an arthrokinetic
reflex caused by distraction. Anterior disc displacement
without reduction (closed lock) could cause spastic activity
in the temporalis muscle on the affected side. Spastic
activity of the masseter and temporalis muscles occurring on
the same side as a joint with anterior disc displacement
hinders or inhibits the condylar movement necessary to
achieve reduction.


DETECTABILITY OF ANTERIOR DISPLACEMENT
OF THE ARTICULAR DISK IN THE
TEMPOROMANDIBULAR JOINT ON HELICAL
COMPUTED TOMOGRAPHY : THE VALUE OF
OPEN MOUTH POSITION, ORAL SURG ORAL
MED ORALPATHOL ORAL RADIOL ENDOD.
1999 (1): 106-11.

(Hayashi T, Ito J, Koyama J, Hinoki A, Kobayashi
F, Torikai Y, Hiruma Y)
Hayashi et al (1999) examined ninety-four consecutive
patients through use of both computed tomography and
magnetic resonance imaging.

They found that in evaluation of articular disk
position, the sensitivity, specidicity and accuracy for
helical computed tomography were 91% , 100%, and
97%, respectively in the closed mouth position and
96%, 99% and 98%, respectively, in the open mouth
position and concluded that the detectability on axial
helical computed tomography of anterior displacement of
the articular disk in the temporomandibular joint in the
open mouth position was almost equal to that on the
magnetic resonance imaging.


COMPARISON OF SKELETAL AND DENTAL
MORPHOLOGY IN ASYMPTOMATIC
VOLUNTEERS AND SYMPTOMATIC
PATIENTS WITH UNILATERAL DISC
DISPLACEMENT WITH REDUCTION.

AO 74:212-219; 2004 (Ioanna K
Gidarakou, Ross H Tallents, Stephanos
Kyrkanides, Scott Stein, Mark E Moss)
Ioanna K Gidarakou et al (2004) evaluated the effect of
unilateral disk displacement with reduction on the skeletal
and dental patterns of the affected individuals using MRI
and lateral cephalogram.

They concluded that alterations in the
skeletal morphology with unilateral disk displacement
with reduction (UDDR) include short anterior and
posterior cranial base, short posterior ramus height

and retro positioned upper and lower denture bases.


Thank you
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