- Most TM disorders are idiopathic,
that is, of unknown origin, some TMD complaints have been associated
with serious organic diseases.
- factors including external trauma, intubation
during general anesthesia, difficult dental extractions,
and orthodontic procedures were evaluated in 195
TMD cases and 50 non-TMD controls.
factors mainly involved developmental abnormalities of the jaws.
Most reports recognized abnormal maxillomandibular relations,
dental or skeletal malocclusions, malalignment of the mandible,
and improper position of the head and the spinal column.
Certain skeletal and dental malocclusions have been suggested as
causing neuromuscular disturbances
in the masticatory system, including TMJ disorders.
The aberrant functions may be either a direct result of
the morphologic malocclusion of and indirect result of
functional occlusal interferences. Potential causes
have been categorized into vertical, horizontal, and lateral
Angle class ¥±, especially division 2, have been
considered particularly vulnerable to TMD. Morphologic
malocclusion, class ¥± and class ¥² occlusions, frontal open bite,
and cross bite if correlated with functional malocclusion,
may predispose to dysfunction bite, if correlated with functional
malocclusion, may predispose to dysfunction. abnotmal
overbite and overjet were associated with condylar DIF.
Excessive overjet was associated with DIF of the disk, patricularly
* DIF-deviation in fom
Functional Malocclusion and Occlusal Disharmonies
Malalignment of the mandible
dysfunction derives from a developmental problem concomitant with
a dental malocclusion. According to this theoretical cause,
and unstable occlusion resulting from either premanture tooth contacts
of parafunctional oral habits causes malaignment of the mandible.
Usually posterior displacement of the mandible results in
compression of the mandible.
Undue stress is placed on muscles, ligaments, and bones. Pain,
impairment of the blood supply, and degeneration of the joint
Based on this malaignment, TMD and malocclusion have been
Condylar displacement originating from occlusal changes was endorsed
as the probable cause of TMD, vertigo, tinnitus, and associated
Significance : A conclusion that condylar displacement caused by
altered occlusion leads to TMD symptomatology must be regarded cautiously.
Improper position of the Head and spinal Column
the TMJ are anatomically close to the spine, it is logical to argue
that the complex of TMJsymptoms includes head, neck and
shoulder problems. There is unsubstantiated opinio that subjects
presenting with forward head posture and protracted shoulders
are prone to TMD.
pathology may derive from various sources.
derangement of the TM joint is defined as an abnormal relation of
mandibular condyle, fossa, and articular eminence. Joint noise or
a history of joint sounds is the key symptom of this
disorder. The most common disk displacement was anteromedial, but
posterior displacement also occurred. Perforations were found
in advanced stages.
Advanced disk displacement characterized Cases of steoarthritis.
Three models have been proposed a causing disk isplacement: hyperextension
of the mandible, condylardisplacement caused by trauma, and chronic
muscular hypertonicity. Hyperextension of the mandible may
result from minor of majo events.
Sudden yawning of prolonged mouth opening are potential minor causes.
An acceleration-deceleration force comparable to the force of whiplash
hyperextend the mandible and induce displacement. A mechanism
has been proposed for disk displacement resulting from
whiplash. incisal clenching has been suggested as a major
etiologic factor in anterior disk displacement.
etiology of TMJ arthritis is unknown. A strong argument has
been made that prior internal derangement leads to TMJ osteoarthritis.
Osteoarthritis may create insidious skeletal changes, simultaneous
intrusion of the teeth, realignment on the ipsilatera side.
changes, caused by the decreased vertical dimension, may include
contralateral anterior open bite with ipsilateral premanture
contact of the molars. Ultimately, these hanges produce facial
deformity and lateral shift of the mandible towards the affected
joint on mouth opening. Potential triggers may
include trauma, iatrogmanipulation, ystemic inflammatory
ilness, of administration of exogenous steroids
is loss of convexity or flattening of the contour of surfaces. remodeling
is charactosseous remodeling and resorption with eventual
decrease in condylar size. The process is slow developing,
insidious, and without hypertrophic changes. Loss of vertical
dimension is probably accomplished by osteoporosis.
5) RHEUMATOID ARTHRITIS.
arthritis is an example of an inflammatory synovitis of unknown
Inflammation develops mainly within the synovial membranes
of the joints. As in osteoarthritis, the major TMD symptoms
are masticatory muscle tenderness and joint crepitation.
A chief difference is that rheumatoid arthritis is a
symmetric synovitis affecting joints bilaterally. Usually
joints of the hands and feet are affected first. The cervical spine
may become involved late in the course of the disease. Patients
may suffer from lateral neck pain as inflammation develops
at the C1-C2 articulation. Orofacial pain may be referred from
of the jaw muscles has long been considered a primary etiologic
factor in TMD. Theoretically, excessive emotional stress
promotes the hyperactivity.
patients with TMD present with widespread tenderness of the muscles
may be a significant factor in causing muscle pain. Levels of tension
may build in the musculature, leading to chronic fatigue
and, potentially, to dysfunction.
trigger point is a tender area in a firm band of muscle tissue.
They populate the muscles of the head, neck, shoulders,
and lower back. Trigger points are thought are thought
to be activated by acute or chronic muscular overload,
fatigue, or trauma.
trigger points of MPD are unilateral.
spinal disorders may lead to complaints often associated with TMD.
Pain may be felt along the side of the head from
disorders of the C2 to C3 vertebrae. A possible mechanism
whereby pathology of the cervical spine could lead to
pain in the trigeminal system would include the
input by way of the upper cervical nerve roots. Cervical spine disorders
may, in fact, in fact, result in bizarre symptoms. These disorders
may involve pain of the head, sinuses, face, ear, and throat.
Sensory disturbances of the pharynx, vertigo, tinnitus, diminished
hearing, sweating, flushing, lacrimation, and salivation are
two different groups of 80 patients, the frequency of recurrent
headache correlated with the frequency of masticatory muscle
pain and TMJ pain on palpation. There is considerable evidence that
headache may arise from myofacial trigger points of masticatory, neck,
and back muscles.
disease may disguise as TMD. A review of the literature found 42
cases of malignancy hat mimicked TMD.
including trigeminal, glosspharyngeal, or atypical(vascular)neuralgias,
contribute little to TMD symptoms. significance:No firm relation
has been established between TMD and neuralgias.
2) VASCULAR DISORDERS.
of TMD-like pain from cardiac origin are rare. Simultaneous presence
of jaw and vascular pain explained by overlap
of cervical nerve C©ý-spinal nerve T©û with the trigeminal
nerve. Significance: Vascular disorders, exclusive
of headache, generallycontribute little to TMD symptoms.
or overbreathing, has been documented as a cause of orofacial pain.
Light-headedness, dizziness, and shortness of
breath were described as classic symptoms
CONNECTIVE TISSUE DISORDERS.
patients with TMD symptoms have connective tissue disease.
> PRECIPITATING FACTORS
as a potential precipitating factor in TMD has created much inspeculation.
Precipitating trauma was identified as the major factor
in causing TMD pain. Trauma may cause specific disturbances
of the TMJ area. Direct injury to the joint has been
proposed as a cause of TMJ osteoarthritis. Sudden changes in the
vertical dimension, caused by disk derangement, have been
suggested as capable of altering the occlusion.
may produce disturbances at specific anatomic sites of the head,
TMJ, and cervical musculature.
often ask if a particular dental treatment causes adverse effects
or improves a preexisting TMD condition. Loss of teeth,
orthodontics, prosthetic treatment, or root canal therapy
are the most frequently asked about procedures.
Loss of Teeth
The overclosure causes the
mandible to be malaligned, resulting in joint disturbances. This
malalignment alters the position of the condyle in the fossa,
which tends to "overload" the joint. Unilateral tooth
loss was common on the side opposite the dysfunction but was identified with the
same side in another study.
Extraction of Teeth
of the mandible during the extraction of molars has been considered
a factor in producing TMD problems.
Although the loss of tooth support or overmanipulation
of the mandible might be detrimental to health
of the TMJs and surrounding soft tissues.
Restoration of the Occlusion
occlusal support is necessary to avoid TMD, then restoration of
the occlusion should reduce or eliminate
If dysfunction is present, restoration should
help lessen the severity.
anecdotal remarks have been made about orthodontics and TMD. Evaluations
of condyle position and vertical overlap of anterior
teeth were made in patients who had the premolars
extracted for orthodontic purposes and in patients without
xtractions. Although some authors argue that orthodontic
treatment superimposed on preexisting subclinic symptoms
may lead to a full blown TMD condition.
Root Canal Therapy
pain may be eliminated by root canal therapy.
It is generally agreed that prolonged
mandibular hyperextension may elicit new or agpreexisting TMD
symptoms. Significance: Although prolonged hyperextension during
root canal therapy may be considered
significant as an etiologic factor.
for the concept that bruxing contributes to dysfunction appears
widespread. Complaints about the masticatory
muscles have received the most attention. TMD symptoms
have been reported among adult bruxers. Positive associations have
been found betweenbruxing and TMD symptoms
Oral Behavioral Patterns
few incidental remarks have been made about chronic chewing of gum
and TMD symptoms.
Jutting of the mandible forward of prolonged lip
biting induced pain in the anterior temporalis muscle.
Interesting associations have been found between oral habits,
muscular changes, facial pain, and different kinds
Reclassification of groups into subjects with
TMJ pain, TMJ and muscle pain, or no facial pain showed
That nocturnal bruxism was more frequent in the combined TMJ
and muscle pain subjects than in other subjects.
3. Emotional Factors
Emotional factors have been suggested as being
involved in the genesis of TMD pain. Patients
with headache, facial pain, or abdominal pain were
less accurate in remembering their pain
than patients with cervical and low back pain. Individuals
who had histories of emotional
stress or home conflicts, who were less active, and
who relied on medication were
most inaccurate in remembering their pain. significance:
Many factors besides pain quality
and quantity influence the discomfort and suffering
associated with recurrent pain.
* This articles from p 87-118 " THE TEMPROMANDIBULAR JOINT
RELATED OROFACIAL DIRORDERS " by Francis M. Bush &