Tmd part i

Manifestations of TMD and
Orthodontic interrelationships-I
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

Contents - I
• Introduction.
• Structural and functional anatomy of the TMJ.
• Biomechanics of movements.
• Prevalence and frequency of TMD`S
• Etiology.
• Signs and symptoms of TMD`S
• Condyle-disc fossa relationships in various malocclusions.
• Malocclusion and TMD`S.
• Functional disorders of the TMJ.
• TMJ imaging.

Contents -II
• TMD`S and occlusal disharmony.
• TMD`S and orthodontic treatment
- extraction of premolars.
- joint sounds.
• TMD`s and orthopedic appliances
- Mandibular advancement appliances
(Does bite jumping effect the TMJ?)
- Herbst, twin block, frankel etc
- Headgears
- Chincup
• TMD`s and orthognathic surgery

• Different condylar modifications.
• Management of TMD`S.
• Treatment modalities.
• Splint therapy.
• Conclusion.
• References.

Introduction
• Temporomandibular disorders (TMD) is a collective
term embracing a number of clinical problems that
involve the masticatory musculature, the TMJ, and
associated structures or both.
• TMD`S are characterized by facial pain in the region
of the TMJ and/or muscles of mastication, limitation
or deviation in the mandibular range of motion and
TMJ sounds during jaw movement and function.
• Causes of most TMD remains unknown, numerous
hypotheses have been proposed however.

• In 1934, James Costen described a group of
symptoms that centered around the ear and TMJ.
Because of his work the term Costen`s syndrome
developed.
• In 1959 Shore introduced the term “TMJ dysfunction
syndrome”.
• In 1971, Ramfjord and Ash coined the term,
“Functional TMJ disturbances”.
• McNeill et al 1980, have suggested a broader term
“Craniomandibular disorders”
• ADA in 1983 adopted the term “Temporomandibular
Disorders”.

Structural and functional anatomy of
the TMJ.
• TMJ -TMJ -
• Ginglymos – hinge type movements.Ginglymos – hinge type movements.
• Synovial jointSynovial joint
• Arthroidal joint – gliding movements.Arthroidal joint – gliding movements.
• Compound + complex joint ( upto 3 bones)Compound + complex joint ( upto 3 bones)
• The articular disc serves as a non ossified thirdThe articular disc serves as a non ossified third
bone which permits complex movements.bone which permits complex movements.
• BicondylarBicondylar
• ““ GINGLYMO ARTHROIDAL JOINT ”GINGLYMO ARTHROIDAL JOINT ”

• Non-ossified bone permits complex movements.Non-ossified bone permits complex movements.
• Composed of dense fibrous connective tissue.Composed of dense fibrous connective tissue.
• Devoid of blood vessels & nerves.Devoid of blood vessels & nerves.
• Divided into 3 regions-Divided into 3 regions-
- Anterior zone- Anterior zone
- Intermediate zone- Intermediate zone
- Posterior zone- Posterior zone
• During movement disc adapts to functionalDuring movement disc adapts to functional
demands of articular surfaces.demands of articular surfaces.
• Disc maintains its morphology unless destructiveDisc maintains its morphology unless destructive
forces occur in joint.forces occur in joint.
Articular DiscArticular Disc

• Articular disc divides the joint into upper and lower
compartments. Passive volume of upper compartment
is 1.2ml and of lower compartment is 0.9ml.
• Two mechanisms of lubrication of the synovial joint.
• Boundary lubrication – it is the primary mechanism
of lubrication. When the joint is moved, synovial fluid
located in border or recess areas is forced on the
articular surfaces and thus provides lubrication and
prevents friction in moving joint.
• Reservoir of synovial fluid.

• Weeping lubrication – during joint function forces
created between the articular surfaces drive small
amounts of synovial fluid in and out of articular
surfaces. Metabolic exchange mainly occurs by this
mechanism. small amounts of friction is eliminated in
compressed joints. prolonged forces exhaust this
supply.
• Momentary high pressure even with extensive
movement is harmless.

• Overloading in occluded position (Bruxism) has the
potential to exceed the protective effect of weeping
lubrication and may predispose to damage.
• Occlusal conditions (normal or abnormal) that
operate prior to intercuspation of the teeth are not
damaging to articular structures, because they do not
violate the limits of weeping lubrication.

Retrodiscal tissue
• Mass of soft tissue that occupies the space behind the
disc and condyle.
• Arises from the posterior band of the disc and
attaches to the squamo-tympanic fissure at the
inferior margin of posterior articular slope of the
condyle.
• Rich blood and nerve supply.
• Made of elastin.

Biomechanics of movements.
• Two types of movements are possible-
• Rotational or hinge movements in the lower
compartment.
• Sliding movements or translation in the upper
compartment.
• During movement stability within each TMJ is
maintained by anterior and posterior disc rotation that
keeps the intermediate zone of disc between the
condyle and eminence.

• Superior retrodiscal lamina rotates the disc
posteriorly and superior lateral pterygoid moves
disc in anterior direction.
• Normal biomechanical function of TMJ must
follow certain orthopedic principles.
- Ligaments do not actively participate in normal
function of TMJ, they act as guide wires restricting
certain movements while permitting others.

• Articular surfaces must be maintained in constant
contact.
• This is achieved by muscles ( elevators, temporalis,
masseter and medial pterygoid) that pull across the
joints and produce this contact.

Prevalence and frequency of
TMD`S

• The prevalence of TMJ signs and symptoms has been
noted in several reports and ranges from 35% to 72%.
• Riolo in AJO (1987) confirmed the surprisingly high
frequency of signs and symptoms of TM Dysfunction
in children and young adults.
• The percent frequency of clicking associated with
overjet was only significant above 6 mm. This is
interesting since traditionally a normal range for
overjet has been loosely defined as being in the 1 to 4
mm range.

• Cusp-to-cusp relationship represented a greater risk
factor for clicking than Class I .Female subjects older
than 12 years with cusp-to-cusp relationships
exhibited higher percent frequencies of clicking than
their Class I cohorts.
• Class II relationship did not consistently appear to be
a greater risk factor for clicking than Class I.
• Buccal crossbite was significantly associated with
clicking, particularly within the oldest ages studied
(15 to 17 years).

• Acc to Montegi et al (AO1992), prevalence of
symptoms in Japanese children is lower about 12 to
20 pc.
• Agerberg (1991) noted incidence of joint sounds to
be 17.5 pc over 2 years in young adults.
• Although epidemiologic data are inadequate, the
number of TMD sufferers in the United States is
estimated at more than 10 million.

Prevalence, Study of Signs and Symptoms of TMD`S
in a Turkish Population. Ozan etal, jcdp 2007
• Women were reported to have signs of TMDs more
than men with as much as a 10-15% greater
frequency of TMJ clicking and more mandibular
osteoarthrosis.
• Compared to Scandinavian and Arab populations the
tenderness or pain in the TMJ was higher while joint
sounds were shown to be of a lower prevalence.

• Epidemiologic studies show that TMD symptoms are
most prevalent among patients between 15 and 25
years old; symptoms then level out as patients
approach age 35.
• Pullinger, Ericksson and Carlson (1987,90)
independently have reported that signs and symptoms
of TMD generally increase in frequency and severity
beginning in the second decade of life.

• Because of the longitudinal nature of orthodontic
treatment an understanding of the changes in the
signs and symptoms of TMD in a healthy population
is essential.
• The occurrence of joint sounds during treatment must
be considered within the context of longitudinal
changes in a comparable untreated population studied
during the same interval.

• The great drive in epidemiologic studies on TMD
came about with Helkimo who developed a clinical
Helkimo index (1974) and the Fonesca`s Anamnestic
index (1992) that quantitatively measured the severity
of TMD symptoms.
• The Craniomandibular Index (
CMI, Friction and Shiffman, 1986)
• The Research Diagnostic Criteria for TMD (
RDC/TMD, Dworkin and LeResche, 1992).

Anamnestic Questionnaire
• Do you find it difficult to open your mouth?
• Do you find it difficult to move your jaw sideways?
• Do you feel discomfort or muscular pain on chewing?
• Do you have frequent headaches?
• Do you have pain in the neck and/or shoulders?
• Do you have earache or pain close to your ears?
• Do you notice any TMJ noise?
• Do you consider your bite "normal"?
• Do you chew on only one side of your mouth?
• Do you have facial pain on waking?

Etiology of TMD`S

• The cause of TMD`S is multifactorial and complex.
• There are numerous factors that can contribute to
TMD.
• Predisposing factors – increase the risk. These
include a mixture of morphological, physiological,
psychological, and environmental variables that
heighten an individual's susceptibility to develop a
certain problem.
• Precipitating factors – cause the onset. These include
various combinations of trauma, stress,
hyperfunction, and possibly failure of natural
inhibiting factors, all of which lead to the onset of
symptoms.

• Perpetuating factors – enhance the progression. These
include poor healing capacity, failure to control
etiologic factors, secondary gains from staying sick,
and negative effects from inappropriate treatments.
(Greene, Seminars in Orthod 1995)

• Occlusal disharmony.
• Malocclusion.
• Orthodontic treatment.
• Malposition or malformation of the condyle
• Abnormal form or position of the glenoid fossa
• Previous trauma
• Bruxism
• Diet
• Stress
• Muscle parafunction
• Oral posture

• Abnormal form or position of the glenoid fossa – it
has been suggested that the fossa itself may be at fault
and certainly there is evidence to suggest that the
temporal bone together with the glenoid fossa, may
be displaced during orthodontic treatment. (Agronin
and Kokich, 1987)
• Studies related to functional appliances show that
glenoid fossa remodels by several mms after the
mandible is held forward. In all these instances the
joint remodels so that the ball was returned to the
centre of the socket.

• Because the joint seems so adaptable in both adult
animals and man , it seems illogical to suggest that
these deformations are the cause of TMD, as they
clearly follow displacement of the joint.
• They should therefore be classified as “resultant”
and not “precipitating”.
• Previous trauma – Wilkes (1989) suggested that
trauma was the single most frequent cause of
subsequent TMD. This explanation is at odds with the
low incidence of TMD in primitive population who
are equally if not more, exposed to damage.

• Follow up of patients who have had fractured
condyles, which must involve substantial trauma to
the joint has shown that they subsequently have few
objective symptoms. (Dahlstrom et al, 1989)
• Bruxism- Intermittent clenching or grinding can
inflict heavy loads on the teeth and joints. However
many people brux and yet have no TMD problems,
and so it would seem that additional factors such as
irregular contacts or previous damage, need to be
present before symptoms will appear.

• Diet – it seems that food either by its consistency or
content could have an influence on the joint. A hard
diet seems to be no disadvantage (Helkimo,1979) but
this is a relatively poorly researched area.
• Stress- it is recognized that emotional stress can
precipitate episodes of TMD (Wadhwa et al,1993)
• It is claimed that there is association between TMD
symptoms, muscle tension, trigger points, headaches
and migraine (Higson,1985)

• Muscle parafunction- EMG studies show that TMD
patients often have abnormal patterns of activity
(Moss, 1975). However this may be the result of
patient`s attempts to avoid premature contacts, rather
than the cause.
• Oral posture- Costen put forward the opinion that
overclosed bites resulted in retropositioning of the
head of the condyle and were associated with TMD.
• Dibbets (1996) have found that increased forward
growth was associated with reduced signs of TMD.

Signs and Symptoms

• Temporomandibular Disorder (TMD) is a term
generally applied to a condition or conditions
characterized by pain and/or dysfunction of the
masticatory apparatus.
• Its characterization has been difficult because of the
large number of symptoms and signs attributed to this
disorder and to variation in the number and types
manifested in any particular patient.
(Cooper BC, Cranio 2007 )

• Symptoms most commonly reported on the
questionnaire included (i) pain (96.1%), (ii) headache
(79.3%), (iii) TMD (75.0%) and (iv) ear discomfort
or dysfunction (82.4%).
• In the 4,338 patients who showed signs, the most
prevalent was tenderness to palpation of the pterygoid
muscles (85.1%), followed by tenderness to palpation
of the TMJ (62.4%).
• Pain symptoms and signs were often accompanied by
compromised mandibular movements, TMJ sounds
and dental changes, such as incisal edge wear and
excessive overbite.

• Clearly prevalence of pain disclosed by the symptoms
and signs examinations was high.
• Patients showed variable prevalence and
nonprevalence of eight categories of painful
symptoms and seven categories of painful signs.

Signs and symptoms of temporomandibular disorders in
adolescents.
Bonjardim LR Braz Oral Res. 2005
• Joint sound during opening was present in 19.8% of
the sample and during closing in 14.7%.
• The most prevalent symptoms were joint sounds
(26.72%) and headache (21.65%).
• There was no statistical difference between genders
except for the tenderness of the lateral pterygoid
muscles, which presented more prevalence in girls.
• In conclusion, clinical signs and symptoms of TMD
can occur in adolescents; however, gender influence
was not perceived.

• An epidemiological study of an African population by
Beighton et al (1973) showed female TMJs are more
mobile than men at any age and general joint mobility is
age-dependent and diminishes most rapidly in childhood.
• Previous studies (Gray 1994,Klienberg 1998) reported
the occurrence of a higher prevalence of signs associated
with mandibular disorder among women.
• The highest prevalence of women classified with some
degree of TMD may be related to typical physiologic
differences between females and males such as regular
hormonal variations, muscular structure, and different
characteristics of the conjunctive tissue.

Malocclusion and TMD`S.

• Malocclusion has been associated with TMD, when it
is believed that the alteration of form might cause
alteration in the stomatognathic system function.
• With the intention of elucidating this relation, several
authors have studied Class I, II malocclusion,
posterior crossbite, anterior open bite, horizontal
overlap and vertical overlap, suggesting that these
alterations are responsible for the onset of TMD
symptoms.
• Corotti et al. (J. Appl. Oral Sci. 2007)

TMD in relation to malocclusion and orthodontic
treatment
Mohlin B, Axelsson S AO 2007
• Associations between certain malocclusions and TMD
were found in some studies, whereas the majority of the
reviewed articles failed to identify significant and
clinically important associations.
• TMD could not be correlated to any specific type of
malocclusion, and there was no support for the belief that
orthodontic treatment may cause TMD. Obvious
individual variations in signs and symptoms of TMD over
time according to some longitudinal studies further
emphasized the difficulty in establishing malocclusion as a
significant risk factor for TMDwww.indiandentalacademy.com

Unilateral posterior crossbite is not associated with TMJ clicking
in young adolescents.
Farella M JDR 2007
• Unilateral posterior crossbite has been considered as
a risk factor for temporomandibular joint clicking,
with conflicting findings. The aim of this study was
to investigate a possible association between
unilateral posterior crossbite and temporomandibular
disk displacement with reduction, by means of a
survey carried out in young adolescents
• Posterior unilateral crossbite does not appear to be a
risk factor for temporomandibular joint clicking, at
least in young adolescents.

• Unilateral posterior crossbite was found in 157
participants (12.2%).
• Fifty-three participants (4.1%) were diagnosed as
having disk displacement with reduction.
• Logistic regression analysis failed to reveal a
significant association between unilateral posterior
crossbite and disk displacement with reduction

Malocclusion traits and symptoms and signs of
temporomandibular disorders in children with severe
malocclusion.
Sonnesen L EJO 1998
• Symptoms and signs of TMD were significantly
associated with distal molar occlusion, extreme
maxillary overjet, open bite, unilateral crossbite,
midline displacement, and errors of tooth formation.
• There is a higher risk of children with severe
malocclusions developing TMD.
• Errors of tooth formation in the form of agenesis or
peg-shaped lateral teeth showed the largest number of
associations with symptoms and signs of TMD
• These associations have not previously been reported in
the literature. www.indiandentalacademy.com

Condyle-disc fossa relationships in
different malocclusions

• TMJ morphology has not been studied adequately in
subjects with various types of malocclusion, and it is
not known if TMJ morphology and facial
morphology are related.
• Such knowledge might assist in the establishment of
biological treatment strategies, especially when the
TMJ is the target of the treatment plan.

Condyle and fossa shape in Class II and Class III
skeletal patterns: a morphometric tomographic study.
Katsavrias EG, Halazonetis DJ.AJO 2005
• Condylar and fossa shapes were found to be different
between the groups; the Class III group had a more
elongated and anteriorly inclined condylar head and a
wider and shallower fossa.
• In the Class III group, the condyle was closer to the
roof of the fossa.
• The 2 Class II divisions differed only in the position
of the condyle in the fossa, which was situated more
anteriorly in the Class II Division 1 group.

Relationship between fossa-condylar position, meniscus position,
and morphologic change in patients with Class II and III
malocclusion.
Zhou D, Hu M, Liang D, Zhao G, Liu A.Chin Den Res 2000
• The variation of condyle-fossa positions for identical
types of malocclusion was very large.
• Skeletal and functional Class III malocclusion
patients demonstrated significantly more anteriorly
positioned condyles.
• Class II division 1 patients showed concentrically
positioned condyles, but with slightly anterior
displacement.
• Class II division 2 patients demonstrated more
posteriorly positioned condyles.
• When condyles were in anterior or concentric
positions, meniscus positions and morphology were
normal and in concavoconcave shapes.www.indiandentalacademy.com

• When condyles were in posterior positions, most
meniscus positions were in normal or slightly anterior
range and their shapes were also concavoconcave.
• The rest were significantly more anterior and their
shapes were abnormal, as evidenced by thickened
anterior bands.
• Class III and Class II division 1 malocclusion
demonstrated normal structure and function of the
TMJ. Class II division 2 malocclusion was obviously
associated with abnormal structure and function of
the TMJ.

Temporomandibular joint morphology and disc position
in skeletal class III patients.
Ueki K J Crani Surg 2000.
• The purpose of this study was to investigate the
relationship between TMJ morphology, including
discal tissue and clinical symptoms in class III
dentofacial deformity patients.
• They were divided into two groups, consisting of a
class III symmetry and a class III asymmetry group.
• The incidence of internal derangement in
asymmetrical class III patients is higher than in
symmetrical mandibular prognathism, and this
difference is associated with a difference in TMJ
morphology of both sides.www.indiandentalacademy.com

• Anteriorly displaced discs in the asymmetry group
(56.8%) occurred significantly more frequently than
in the symmetry group (18.2%)
• TMJ symptoms (clicking, crepitus, closed lock, pain)
were seen in 17/44 joints (38.6%) of the symmetry
and 24/44 joints (54.5%) of the asymmetry group

The relationship between temporomandibular joint disc
morphology and stress angulation in skeletal Class III
patients.
Ueki K EJO 2005.
• There was also a significant correlation between disc
position and stress angulation.
• Stress angulation was higher at the deviation side as
compared to the non deviation side.
• In the asymmetry group, a significant correlation
between the difference in stress angulation (between
the deviation side and the non-deviation side) and the
degree of asymmetry (measured by the angle of
asymmetry).

Computed tomography evaluation of temporomandibular joint
alterations in patients with class II division 1 subdivision
malocclusions: condyle-fossa relationship.
Vitral RW, Telles Cde S, Fraga MR, de Oliveira RS, Tanaka OM
.AJO 2004
• No statistically significant asymmetries were found in
the depth of the mandibular fossa, the angulation of
the posterior wall of the articular tubercle, or the
condyle-fossa relationship.
• However, a statistically significant (P <.05) anterior
positioning of the condyles was observed.

Morphology of the temporomandibular joint in subjects with
Class II Division 2 malocclusions.
Katsavrias EG.AJO 2006
• The results suggest that fossa morphology and
condylar length attain their final sizes early.
• articular eminence and ramus morphology (height,
inclination) have great variability
• some joint components such as eminence height with
eminence inclination, eminence height with ramus
inclination, eminence inclination with ramus
inclination, and fossa anteroposterior dimensions are
highly correlated with each other
• the most prevalent condylar and fossa anteroposterior
shape is oval.

Condylar position and Class II deep-bite, no-overjet
malocclusions.
Gianelly AA, Petras JC, Boffa J. AJO 1989
• By means of corrected tomography, the positions of
the condyles in 19 click-free persons with Class II
malocclusions characterized by a bite depth greater
than 50%, no overjet, and an interincisal angle of
greater than 140 degrees were compared with a
positions of the condyles in 21 control subjects.
• Average condylar position in both groups was
concentric and no significant differences between
groups were found. In addition, no significant
correlation was noted when condylar position was
related to bite depth.

Comparison of deep bite and open bite cases: normative
data for condylar positions, paths and radiographic
appearances.
Ari-Demirkaya A .J Oral Rehab 2004
• Results of this study showed that open bite cases
show larger vertical CR-CO slides and, shorter
protrusion paths than normal and deep overbite cases.
• Open bite cases had significantly shorter condylar
paths.
• The erosion rates were higher in the open bite group,
but flattening was seen more often in the deep bite
group
• This study indicates that the clinician should be
paying special attention to the TMJ status of open
bite patients.

An evaluation of mandibular asymmetry in adults with
unilateral posterior crossbite. ajo 1995
O'Byrn BL, Sadowsky C, Schneider B, BeGole EA.
• A retrospective study was conducted to determine
whether mandibular symmetry in adults with
untreated unilateral posterior crossbite was different
from that found in adults with untreated Class I
malocclusions.
• Skeletally, the mandible showed no asymmetry.
Relative to the cranial floor, the mandible was
"rotated" so that the condyle on the crossbite side was
positioned relatively posteriorly in comparison to the
contralateral side.

• A relative posterior positioning of the glenoid fossa
was inferred, since there was no demonstrable
mandibular skeletal asymmetry or condylar
displacement within the fossa as shown on corrected
tomograms in the crossbite group as compared with
the Class I group
• The results question whether it is appropriate to
correct unilateral posterior crossbites in adults by
orthodontic tooth movement alone, given the skeletal
remodeling in the temporomandibular joint, which
may have already occurred.

Transverse skeletal and dental asymmetry in adults with
unilateral lingual posterior crossbite.
Langberg BJ, Arai K, Miner RM.ajo 2005
• A statistically significant difference in mandibular
transverse dental asymmetry was observed between
adults with PUXB and the control group.
• However, no significant differences were found in
the right-left skeletal asymmetry, although the PUXB
group showed more positional deviation of the
mandible.
• Moreover, condylar position analysis indicated that
the crossbite group did not show any greater
functional shifts than the control group.

• We concluded that PUXB in adults is primarily due
to dentoalveolar asymmetry and positional deviation
of the mandible and not simply to right-left skeletal
asymmetry of the mandible.
• These data suggest that untreated PUXB in children
might lead to progressive asymmetric compensation
of the condyle-fossa relationship and result in a
positional deviation of the mandible, which, along
with a distinct dentoalveolar asymmetry, maintains
the crossbite occlusion in adults.

Functional disorders of the TMJ.

• They can be broadly divided into 3 categories,
• Derangements of the condyle- disc complex. Internal
derangement of the TMJ can be defined as an
abnormal relationship between the intra-articular disc
and the condyle when the teeth are in occlusion.
- disc displacements with reduction
- disc displacements without reduction.
• Structural incompatibility of the articular surfaces.
- deviations, adhesions, subluxation and dislocation.
• Inflammatory joint disorders.

Disc displacements with reduction

Disc displacements without reduction

• Considerable attention has been given in the literature to
the clinical significance of reciprocal clicking of the
TMJ, with the implicationthat it is a more serious
situation than the mere presence of a click on opening of
the mouth.
• Actually, the same changes in the disc Condyle
relationship occur whether or not a click is heard on
mouth closure. In patients whose TMJ clicks every time
they open their mouth, the disc has to slip off the
condyle during mouth closure so that the process can
repeat itself.

• The difference is that, in some patients, the passage of
the condyle over the posterior band as the disc again
slips forward during closure is associated with a
clicking sound, but in others it occurs silently and can
only be detected by the slight jarring sensation felt by
palpation over the joint or the mandibular angle.
• Thus, the presence or absence of reciprocal clicking
does not seem to have any real clinical significance.

TMJ imaging
• Although many of the disorders involving the TMJ
and associated structures can be diagnosed clinically
on the basis of the history and physical findings, there
are others that require the use of various imaging
techniques to make an accurate diagnosis or to
determine the extent of involvement.
• To take maximum advantage of the benefits of these
procedures, however, it is not only important for the
clinician to be able to select the correct methods, but
also to understand their limitations as well as their
capabilities.

Transcranial Radiographs
• Transcranial radiography (TR) has been used
extensively as a diagnostic aid for TMDs, partly
caused by the technique's simplicity and the wide
availability of the required equipment.
• Historically, transcranial radiographs have been used
to evaluate the status of joint hard tissue and the
spatial relationship of the condyle to the fossa.

Transmaxillary Radiography
• This technique provides a frontal view of the TMJ,
sometimes referred to as the transantral, transorbital,
or infraorbital projection. The entire mediolateral
profile of the condyle is imaged, making this view a
very useful supplement to a saggital view, such as the
transcranial projection. Used together, the views
provide a three-dimensional perspective not possible
with either of the views alone.

Computed tomography
• CT has good validity for diagnosing osseous
abnormalities. However, tomography should be
considered for this purpose because it costs much less
and its validity is comparable with that of CT.
Probably the best use of CT is for diagnosing
intraosseous lesions.
• Moreover, CT has a large area of coverage that is not
only useful for diagnosing tumors in theTMJ, which
are very rare, but also in adjacent anatomic regions.

Arthrography
• Arthrography is a technique used to highlight or
outline joint structures by using a radiopaque contrast
medium to enhance their images on plane or
tomographic films.
• In the case of the TMJ, the contrast medium is
injected into the upper or lower joint space or both.
The disc then appears as a radiolucent mass against
the background of contrast medium on conventional
radiographs, tomography, or fluoroscopy.

Magnetic Resonance Imaging
• Magnetic resonance imaging (MRI) has several
distinct advantages over previously discussed
imaging techniques.
• Chief among these advantages is the substitution of
relatively harmless superconducting magnets and
radio wave energy for the well known hazards of
ionizing radiations.
• Method of choice to assess disc position in open and
closed mouth positions.

References
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Bondemark L, Brattström V, Hansen K, Holm AK
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Feb;86(2):137-41
3. Ueki K, Nakagawa K, Takatsuka S, Shimada M,
Marukawa K, Takazakura D, Yamamoto E
.Temporomandibular joint morphology and disc
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4. Katsavrias EG, Halazonetis DJ Condyle and fossa
shape in Class II and Class III skeletal patterns: a
morphometric tomographic study. AJO
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5. Katsavrias EG Morphology of the TMJ in subjects
with Class II Division 2 malocclusions.
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6. Gianelly AA, Petras JC, Boffa J Condylar position
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