Tmd / dentistry orthodontics

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Contents
Introduction
History
Definitions
Classification
Epidemiology
Etiology
Development of functional disturbances in
masticatory system
Predisposing factors
Initiating factors
Perpetuating factors.

Occlusal conditions
Parafunctional habits
Trauma
Emotional stress
Deep pain output
Signs and symptoms of TMDS
Functional disorders of muscles
Functional disorders of TMJ
Functional disorders of teeth
Other signs and symptoms
Summary
Conclusion
References

 Introduction:
 The masticatory apparatus is specialized unit that
performs multiple functions including those of speaking,
cutting & grinding food & swallowing.
 TMJ disorder (TMD) are among the most misdiagnosed &
mistreated maladies in medicine.
 Multifactorial origin
 The term TMD are collective term embracing a member
of clinical problems that involve the masticatory
musculatures, the TMJ & associated structure or both

This disorders are characterized by
 Facial pain in the region of the TMJ & for the muscle of
mastication.
 Limitation or deviation in the mandibular range of
motion.
 TMJ sounds during jaw movements & function.
 History:
 348 BC: Hippocrates described a condition of TMJ
dislocation.
 1814: Hey had described internal derangement for a
localized mechanical fault interfering with smooth
articular function.

1842: Cooper reported on subluxation of the TMJ as a
distinct entity. He observed patients with snapping jaw &
registered this symptom as an “ internal derangement of
the jaws”
1887: Surgical correction was described by Annandale.
1918: Pringle explained clicking & popping of the TMJ as a
sign of anterior displacement of the meniscus.
1934: Costen was first to indicate an occlusal etiology in
TMJ pain. He reported association of the bite over closure
with symptoms like ear pain, sinus pain, decreased
hearing, tinnitus, dizziness, burning & vertigo & occipital
headache.

1947: Norgaard used orthographic techniques to
radiographically demonstrate anterior disc displacement
in clicking or popping TMJ.
1950-60: muscular cause not directly related to occlusion
was proposed
Schwartz coined the term Temporomandibular pain
syndrome.
1970: advances in diagnostic imaging have resulted a
better understanding of the intracapsular problem
associated with TMD.
Farrar & McCarthy rejuvenated the concept of internal
derangement with meniscus displacement.

Definition of TMD
Acc to Schiffman, Haley, Shapiro (1990)
the TMD encompasses many disorders of the masticatory
musculature (i.e. myositis, muscle spasm, muscle
contracture, & myofascial pain syndrome)
and TMJ ( internal derangements with or without
reduction and degenerative joint disease)
The AAOP ( in 1993 & 1996) refined TMD as a
collective term embracing a number of clinical problems
that involve the masticatory musculature, the
temporomandibular joint and associated structures or
both.

GPT - 8
Conditions producing abnormal , incomplete or impaired
function of the temporomandibular joint.
A collection of symptoms frequently observed in various
combinations first described by Costen (1934) which he
claimed to be reflexes due to irritation of the
auriculotemporal nerve and / or corda tympanic nerve as
they emerged from tympanic plate.

It is caused by altered anatomic relations and
derangements of the TMJ associated with loss of
occlusal vertical dimension, loss of posterior tooth
support, and / or other malocclusions. The symptoms
can include headache about the vertex and occiput,
tannitus, pain about the ear, impaired hearing and
pain about the tongue.

Classification of diseases of Temporomandibular
joint
 Bell in 1960
 3 subgroups:
 Intracapsular conditions
 Capsular conditions
 Extracapsular conditions
 In 1982, 5 subcategories
 Masticatory muscle disorder
 Disk interference disorder
 Inflammatory disorder
 Chronic hypomobilities
 Growth disorders

Acc. to American Academy of Orofacial Pain
Diagnostic category Diagnosis
Cranial bones Congenital & developmental disorders
Aplasia
Hypoplasia
Dysplasia(1st
& 2nd
brachial arch
anomalies, hemifacial microsomia,
Pierre syndrome, Treacher Collin
syndrome)
Condylar hyperplasia
Prognathism, fibrous dysplasia.
Acquired disorders
Neoplasia
Fracture

Temporomandibular joint
disorders
Deviation in form
Disk displacement
(with reduction; without reduction)
Dislocation
Inflammatory conditions (synovitis,
capsulitis)
Arthritides (osteoarthritis,
osteoarthrosis polyarthritides)
Ankylosis (fibrous, bony)
Neoplasia
Masticatory muscle
disorders
Myofascial pain
Myositis
Spasm
Protective splinting
Contracture 15www.indiandentalacademy.com

Epidemiology
Between 65 and 85% of people experience some symptoms
of TMD during their lives, and approximately 12% experience
prolonged pain or disability that results in chronic
symptoms.
Only about 5 to 7% have symptoms severe enough to need
treatment.
TMD patients are similar to headache and back pain patients
with respect to disability, psychosocial profile, and pain
intensity, chronicity, and frequency.

The lower prevalence of TMD signs and symptoms in
older age groups supports the probability that most TMD
are self-limiting.
TMD are most prevalent between the ages of 20 and 40
years and predominantly affect women.
The reason why women make up the majority of patients
presenting for treatment is still unclear.
In a community-based study, a greater likelihood of
developing TMD was found if oral contraceptives were
used and, in women over 40 years of age, if estrogen
replacement was used.

While the prevalence of TMD is highest in the 20-
to 40-year age range, signs and symptoms of masticatory-
muscle and joint dysfunction are commonly observed in
children.
The cause may be acute reactive depression, disk
displacement, with or without reduction, internal
derangement due to previous injury.

Development of functional
disturbances in the masticatory
system
TMD symptoms
Normal
function
+
event
>physiologic tolerance
=

Normal fuction
Chewing
swallowing
speaking
carried out by the complex neuro muscular control
system.

Events
During normal function of the masticatory system,
events can occure that may influence function.
Local events
systemic events.

Local events
Any change in sensory or proprioceptive input.
Placement of improperly occluding crown
or it may be secondary to trauma involving local
tissues e.g. post injection response of L.A.
trauma due to wide opening (i.e. strain) or
unaccustomed use (i.e. bruxisum).

systemic events
The entire body and CNS are involved.
E.g. emotional stress.

Physiologic tolerence
All individuals do not respond in the same manner to
the same event.
Each patient has the ability to tolerate certain events
without any adverse effect this is called physiologic
tolerance which can be influenced by both local and
systemic factors.

Local factors
Lack of occlusal stability- genetic, developmental, or
iatrogenic causes.
TMJ instability- alteration in normal anatomic form
e.g.- disc displacement, arthritic conditions, lack of
harmony between stable intercuspal position (ICP)
and musculoskeletally stable (MS) position of the
joint.

Systemic factors
Systemic factors which influence the patient’s
physiologic tolerance are, genetic, gender, diet, acute
and chronic diseases, overall physical condition of the
patient.

Structural tolerance and
development of symptoms.
When functional change exceeds a critical level,
alteration of tissues begins this level is called
structural tolerance level.
The initial breakdown is seen in the structures with
the lowest structural tolerance.
Therefore the breakdown sites varies from individual
to individual.

 The etiology of TMD remains mired in
controversy. It is generally agreed that the
etiology of symptoms of TMD is
multifactorial. That is several different
factors acting alone, or in varying
combinations may be responsible.

 Predisposing factor – factors that increase the risk
of TMD or orofacial pain developing.
 Initiating factors – factors that cause the onset of
disorder.
 Perpetuating factors – factors that interfere with
healing and complicate management .

 Predisposing factors can be subdivided into :
Systematic factors – medical conditions such as
rheumatic infections, nutritional and metabolic
disorders can influence masticatory system to an
extent that TMD may emerge.
Psychologic factors - Personality, behaviour can
affect masticatory system.

Structural factors – All types of occlusal
discrepancies, improper dental treatment,
postural abnormalities ,skeletal deformation, past
injuries etc.
Genetic factors.

 Direct precipitating or initiating
component:
Trauma from hyperextension (e.g. dental procedure,
oral intubation for G. A., yawning, hyperextension
associated with cervical trauma)
Micro & macro trauma
Adverse or overloading of joint structures
Parafunctional habits (nocturnal bruxing, tooth
clenching, lip or cheek biting)

 Perpetuating factors or sustaining factors:
Mechanical & muscular stress
Metabolic problems
Mainly behavioral, social & emotional
difficulties

Five major factors associated with TMD
1) Occlusal condition
2) Trauma
3) Emotional stress
4) Deep pain input
5) Parafunctional activities.

occlusal condition.
Pullinger et al. (j prosthet dent 2000,83:66-75),
studied 11 possible occlusal factors.
Concluded that,
 No single occlusal factor was able to differentiate
patient from healthy subjects.
Four factors, however occurred mainly in TMD
patients and were rare in normal subjects

1) The presence of a skeletal anterior open bite.
2) Retruded contact position (RCP) and ICP slides of
greater than 2mm.
3) Overjets of greater than 4mm.
4) Five or more missing and unreplaced posterior
teeth.

Dynamic relationship between
occlusion and TMD
Occlusal conditions affects TMD by one of the two
ways
1) Occlusal conditions affects the orthopedic stability
of the mandible.
2) Acute changes in occlusion .

41
Occlusion and
orthopedic
stability

Occlusion and orthopedic stability

Degree of orthopedic instability- discrepancy more
than 1-2 mm
Amount of loading- bruxers are affected more than
nonbruxers

Acute changes in occlusion and
TMD
Mainly affects the activities of masticatory muscles.
Muscle activities are basically divided in to
 1) Functional (chewing, speaking, swallowing)
2) Parafunctional (clinching and bruxism)

Occlusal contacts and muscle
hyperactivity
Precise effect of the occlusal condition on muscle
hyperactivity has not been clearly established.
Williamson and Landquist demonstrated that
certain posterior contacts can increase activity of
the elevator muscles.
But Rugh et al. Shown that premature occlusal
contacts do not increase bruxing activity (no
correlation between occlusal contacts and muscle
activities).

The difference between first and second study:- first
study assesed the effects of occlusal contacts on
conscious and controlled, voluntary mandibular
movements (controlled by peripheral nervous system)
while the second study assessed subconscious and
uncontrolled, involuntary muscle activity (bruxisum)
(controlled by CNS).

Thus sudden changes that disrupts the ICP can lead
to a protective response of the elevator muscles (i.e.
protective co-contraction) in conscious state which
may lead to pain.
But this increased tonus or change in ICP do not
cause any increase in bruxing activity which is
controlled by CNS.

Chronic occlusal interferences
1) Most common way is to alter muscle engrams so as
to avoid the potentially damaging contacts and get on
with the task of function.
2) Tooth movement to accommodate heavy loading.
Bruxism never occurs or accentuates because of
occlusal problems.

Problems with bringing the teeth into occlusion are
answered by muscles. However, once the teeth are in
occlusion, problem with loading the masticatory
structures are answered in the joints.
Therefore if one of these conditions exists, dental
therapy is likely indicated.

Trauma
Trauma seems to have greater influence on
intracapsular disorders than muscular disorders.
Two types
1) Macrotrauma- any sudden force that can result
in structural alteration e.g. blow on the face.
2) Microtrauma:- any small force that is repeatedly
applied to the structures over a long period of time
e.g. bruxism, clinching.

Macro trauma
Sudden force on the condyle.
It can be direct or indirect.
The direct macro trauma can be open mouth trauma
or closed mouth trauma.

Open mouth direct macro
trauma
Blow to the chin, when the teeth are separated (i.e.,
open-mouth trauma)- the condyle can be suddenly
displaced from the fossa - ligaments resist this sudden
displacement.
If the force is great, the ligaments can become
elongated - resulting increased looseness can lead to
discal displacement and to the symptoms of clicking
and catching.
Unexpected macrotrauma to the jaw (as might be
sustained during a fall or in a motor vehicle accident)
may lead to discal displacement, dislocation, or both.

Closed mouth direct macro trauma
Macrotrauma can also occur when the teeth
are together (i.e., closed-mouth trauma) - the
intercuspation of the teeth maintains the jaw
position, resisting joint displacement.
Closed-mouth trauma is therefore less injurious to
the condyle-disc complex.
Athletes who wear soft, protective mouth
appliances have significantly fewer jaw-related
injuries than those who do not.

Although ligaments may not be elongated,
articular surfaces can certainly receive sudden
traumatic loading. This type of impact loading may
disrupt the articular surface of the condyle, fossa
or disc, which may lead to alterations in the
smooth sliding surfaces of the joint, causing
roughness and even sticking during movement.
Therefore this type of trauma may result in
adhesions.

Indirect macro trauma
Indirect trauma refers to injury that may occur to the
TMJ secondary to a sudden force, but not one that
occurs directly to the mandible. The most common
type of indirect trauma reported is associated with a
cervical flexion-extension injury (i.e., whip-lash
injury).

Microtrauma
Microtrauma refers to any small force that is
repeatedly applied to the joint structures over a long
period of time loading exceeds the function-al limit of
the tissue, irreversible changes or dam-age can result.
When the functional limitation has been exceeded,
the collagen fibrils fragmented, resulting in a
decrease iness of the collagen network. This allows
proteoglycan-water gel to swell and flow out the joint
space, leading to a softening of articular surface. This
softening is called chondromalacia.

Regions of fibrillation can begin to develop, resulting
in focal roughening of the articular surfaces. This
alters the frictional characteristics of the surface and
may lead to sticking of the articular surfaces, causing
changes in the mechanics of condyle-disc movement.
Continued sticking, roughening, or both leads to
strains on the discal ligaments during movements
and eventually to disc displacements.
Another way in which micro trauma affects is the
hypoxia-reperfusion theory.

Another type of microtrauma results from
mandibular orthopedic instability. As previously
described, orthopedic stability exists when the stable
ICP of the teeth is in harmony with the
musculoskeletally stable (MS) position of the
condyles
Bruxing patients with orthopedic instability are more
likely to create problems than nonbruxers with the
same occlusion.

Emotional stress
The emotional centers of the brain have an influence
on muscle function
Stress - activates hypothalamus - increase the activity
of the gamma efferents - the intrafusal fibers of the
muscle spindles contract.
Stress releasing mechanisms:- external and internal

Deep pain input
Deep pain input- centrally excites the brain stem-
produces muscle response (protective co-contraction)
It is normal body response to pain.
Intraoral pains like tooth pain, sinus pain, ear pain or
even remote facial pains like cervical pain input may
restrict the mouth opening.

Parafunctional activities
Two types
1) Diurnal- occurs during day.
2) Nocturnal - occures during night.
DIURNAL ACTIVITIES - clinching and grinding,
cheek and tongue biting, finger and thumb
sucking, unusual postural habits, occupation
related habits e.g. holding nails, pen in mouth,
holding objects like telephone, violin under the
chin.

Nocturnal activities
Clinching (single episode of muscular contraction)
Bruxing (rhythmic contractions)
causes of bruxing activities
emotional stress, certain medications, genetic
predisposition, CNS disturbances, occlusal
interferences ???

Etiological concepts :
 Mechanical displacement theory:
 Neuromuscular theory:
 Muscle theory:
 Psycophysiological theory:
 Psychological theory:

A sign is an objective clinical finding that the
clinician uncovers during a clinical examination.
A symptom is a description or complaint reported by
the patient
patients are acutely aware of their symptoms yet may
not be aware of their clinical signs.

Clinical signs and symptoms of TMDs can be grouped
according to the structures affected
1) the Muscles.
2) the TMJs
3) the Dentition

Functional disorders of the
muscles
Two major symptoms
1) Pain
2) Dysfunction.

Pain
Pain felt in musculature is called myalgia.
Often associated with fatigue and tightness.
It is related to vasoconstriction of the relevant
nutrient arteries and accumulation of metabolic waste
products. Within the ischemic area of the muscle,
certain algogenic substances (e.g. bradykinin,
prostaglandins) are released, causing muscle pain

The severity of muscle pain is directly related to the
functional activity of the muscle involved. Therefore
patients often report that the pain affects their
functional activity.
When a patient reports pain during chewing or
speaking, these functional activities are not usually
the cause of the disorder.

Myogenous pain is a type of deep pain and, if it
becomes constant, can produce central excitatory
effects. These effects may present as sensory effects
(i.e.referred pain or secondary hyperalgesia) or
efferent effects (i.e. muscle effects), or they may even
present as autonomic effects.
Muscle pain can reinitiate more muscle pain (i.e., the
cyclic effect).
Another very common symptom associated with
masticatory muscle pain is headache.

Dysfunction
A decrease in the range of mandibular movement.
When muscle tissues have been compromised by
overuse, any contraction or stretching increases the
pain. Therefore to maintain comfort, the patient
restricts movement within a range that does not
increase pain levels. Clinically this is seen as an
inability to open widely.

An acute malocclusion may result from a sudden
change in the resting length of a muscle that controls
jaw position. When this occurs the patient describes
a change in the occlusal contact of the teeth.
The mandibular position and resultant alteration in
occlusal relationships depend on the muscles involved.
For example, slight functional shortening of the
inferior lateral pterygoid will cause disocclusion of the
posterior teeth on the ipsilateral side and premature
contact of the anterior teeth (especially the canines)
on the contralateral side.

With functional shortening of the elevator
muscles (clinically a less detectable acute
malocclusion), the patient will generally complain
of an inability to occlude normally. It is important
to remember that an acute malocclusion is the
result of the muscle disorder and not the cause

Masticatory muscle model

Events
Various types of events can interrupt normal muscle
function. These events can arise from either local or
systemic factors
Local events that acutely alter sensory or pro-
prioceptive input in the masticatory structures .
Systemic factors may also represent events that can
interrupt normal muscle function.

Local events
1) Fracture of tooth
2) Restoration in supraocclusion
3) Trauma to local tissues e.g. L.A. inj
4) Chewing hard food
5) Chewing for long period
6) Opening mouth too widely e.g. yawning, dental
treatments

Systemic events
1) Emotional stress
2)Acute illness.
3)Viral infections
4)Age
5)Gender
6)Diet
7)Genetic predisposition

Protective co-contraction
Protective co-contraction is a CNS response to injury or
threat of injury. This response has also been called
protective muscle splinting.
 In the presence of an injury or threat of injury, normal
sequencing of muscle activity seems to be altered to
protect the threatened part from further injury.
 This coactivation of antagonistic muscles is thought to be
a normal protective or guarding mechanism . If protective
co-contraction continues for several hours or days, the
muscle tissue can become compromised and a local
muscle problem may develop.

Local muscle soreness
Local muscle soreness is a primary, noninflammatory,
myogenous pain disorder (i.e., noninflammatory myalgia).
It is often the first response of the muscle tissue to
prolonged co-contraction.
Although co-contraction represents a CNS-induced
muscle response, local muscle soreness represents a
condition characterized by changes in the local
environment of the muscle tissues.
These changes are characterized by the release of certain
algogenic sub-stances (i.e., bradykinin, substance P, and
even histamine) that produce pain.

Along with protracted co-contraction, other causes of
local muscle soreness are local trauma or excessive use
of the muscle.
 When excessive use is the cause, a delay in the onset
of muscle soreness can occur
Local muscle soreness presents clinically with muscles
that are tender to palpation and reveal increased pain
with function. Structural dysfunction is common, and
limited mouth opening results when the elevator
muscles are involved.

CNS EFFECTS ON MUSCLE PAIN
Activities within CNS either influence or
originates muscle pains
The CNS responds in this manner secondary to
one of three factors:
(1) the presence of ongoing deep pain input,
(2) increased levels of emotional stress (i.e., up-
regulation of the autonomic nervous system), or
(3) changes in the descending inhibitory system that
lead to a decrease in the ability to counter the
afferent input.

CNS induced muscle pain disorders are
1) Myospasm
2)Myofacial pain (trigger point myalgia)
3)Centrally mediated myaligia (chronic myocitis)
4)Chronic systemic myalgic disorders (fibromyalgia)

Perpetuating factors in myalgia
Local perpetuating factors
1) Protracted cause
2)Recurrent cause
3)Therapeutic mismanagement.

Systemic perpetuating factors
1) Continued emotional stress
2)Sleep disturbances
3)Learned behavior
4)Secondary gain
5)Depression

They generally fall into three broad categories:
(1)derangements of the condyle-disc complex,
(2)structural incompatibility of the articular surfaces,
and
(3)inflammatory joint disorders

The two major symptoms of functional TMJ problems
are pain and dysfunction.
PAIN
Pain in any joint structure (including the TMJs) is
called arthralgia .
Three periarticular tissues contain such nociceptors:
(1) the discal ligaments, (2) the capsular ligaments,
and (3) the retrodiscal tissues.

Stimulation of the nociceptors creates inhibitory
action in the muscles that move the mandible.
Therefore when pain is suddenly and unexpectedly
felt mandibular movement immediately ceases (i.e.,
nociceptive reflex).
When chronic pain is felt, movement becomes
limited and very deliberate (i.e., protective co-
contraction).

Arthralgia from normal healthy structures of the joint
is a sharp, sudden, and intense pain that is closely
associated with joint movement. When the joint is
rested, the pain resolves quickly.

DYSFUNCTION
It presents as a disruption of the normal condyle-disc
movement, with the production of joint sounds .
 The joint sounds may be a single event of short
duration, known as a click.
If this is loud it may be referred to as a pop.

Crepitation is a multiple, rough, gravel-like sound
described as grating and complicated.
Dysfunction of the TMJ may also present as catching
sensations when the patient opens the mouth.
Sometimes the jaw can actually lock.

CONTINUUM
OF FUNCTIONAL
DISORDERS OF
THE
TMJ

CONTINUUM OF FUNCTIONAL
DISORDERS OF THE TMJ
Disorders of the TMJs may follow a path of pro-
gressive events, a continuum, from the initial signs of
dysfunction to osteoarthritis

1. Normal healthy joint
2. Loss of normal condyle-disc function the result of
either:
a. Macrotrauma that resulted in elongation of the
discal ligaments
b. Microtrauma that created changes in the articular
surface, reducing the frictionless movement between
the articular surfaces
3. Significant translatory movement begins between disc
and condyle (resulting in displacement of disc)
4. Posterior border of disc becomes thinned
5. Further elongation of discal and inferior
retrodiscal ligaments

6. Disc becomes functionally displaced
a. Single click
b. Reciprocal click
7. Disc becomes functionally dislocation
a. Dislocation with reduction (i.e. catching)
b. Dislocation without reduction (i.e. closed lock)
8. Retrodiscitis
9. Osteoarthritis

CONTINUUM
OF FUNCTIONAL
DISORDERS OF
THE
TMJ

Derangements of the Condyle-Disc
Complex
If the morphology of the disc is altered and the discal
ligaments become elongated, the disc is then
permitted to slide (i.e., translate) across the articular
surface of the condyle.

Alteration in the morphology of the disc accompanied by
elongation of the discal ligaments can change this normal
functioning relationship. In the resting closed joint position
the interarticular pressure is very low. If the discal ligaments
become elongated, the disc is free to move on the articular
surface of the condyle. Because in the closed joint position
the superior retrodiscal lamina does not provide much
influence on disc position, tonicity of the superior lateral
pterygoid muscle will encourage the disc to assume a more
forward position on the condyle.
The length of the discal ligaments and the thickness of the
posterior border of the disc will limit forward movement of
the disc.

If the pull of this muscle is protracted, over time
the posterior border of the disc can become more
thinned
This is called as functional disc displacement.

Reciprocal click 105www.indiandentalacademy.com

1)During mandibular opening a sound is heard that
represents the condyle moving across the posterior
border of the disc to its normal position on the
intermediate zone. The normal disc-condyle
relationship is maintained through the remaining
opening movement.
2)During closing the normal disc position
is maintained until the condyle returns
to very near the closed joint position.
Characteristics of reciprocal click

3)As the closed joint position is approached, the
posterior pull of the superior retrodiscal lamina is
decreased.
4)The combination of disc morphology and pull of the
superior lateral pterygoid allows the disc to slip back
into the more anterior position, where movement
began. This final movement of the condyle across the
posterior border of the disc creates a second clicking
sound and thus the reciprocal click.

As the disc becomes more flat, it further loses its
ability to self-position on the condyle, allowing more
translatory movement between condyle and disc.
 The more freedom of the disc to move, the more
positional influence from the attachment of the
superior lateral pterygoid muscle.
Eventually the disc can be forced through the discal
space, collapsing the joint space behind.

When this occurs, interarticular pressure will
collapse the discal space, trapping the disc in the
forward position.
Then the next full translation of the condyle is
inhibited by the anterior and Medial position of
the disc.
The person feels the joint being locked in a limited
closed position because the articular surfaces have
actually been separated, this condition is referred
to as a functional dislocation of the disc

Functional dislocation Vs functional displacement
As previously described, a functionally displaced disc
can create joint sounds as the condyle skids across the
disc during normal translation of the mandible .If the
disc becomes functionally dislocated, the joint sounds
are eliminated because no skidding can occur.

Some persons with a functional dislocation of the
disc are able to move the mandible in various
lateral or protrusive directions to accommodate
the movement of the condyle over the posterior
border of the disc, and the locked condition is
resolved. If the lock occurs only occasionally and
the person can resolve it with no assistance, it is
referred to as a functional dislocation with
reduction. The patient will often report that the
jaw "catches" when opening wide.

Functional dislocation of the disc with reduction

when person is unable to return the dislocated disc to its
normal position on the condyle. The mouth cannot
be opened maximally because the position of the disc
does not allow full translation of the condyle .
Typically the initial opening will be only 25 to 30 mm
interincisally, which represents the maximum rotation of
the joint.
The person usually is aware of which joint is involved
and can remember the occasion that led to the locked
feeling. Because only one joint usually becomes locked,
a distinct pattern of mandibular movement is
observed clinically.

The joint with the functionally dislocated disc
without reduction does not allow complete
translation of its condyle, whereas the other joint
functions normally. Therefore when the patient opens
wide, the midline of the mandible is deflected to the
affected side. The dislocation without reduction has
also been termed a closed lock.

Closed lock / functional dislocation without reduction

Structural Incompatibility of the
Articular Surfaces
Smooth articulation of the TMJ is ensured by two
mechanisms: (1) boundary lubrication and (2) weeping
lubrication.
If static loading continues for a prolonged time, however,
weeping lubrication can become exhausted and sticking of
the articular surfaces can result. When the static loading is
finally discontinued and movement begins, a sense of
stiffness is felt in the joint until enough energy is exerted
to break apart the adhering surfaces.
This breaking apart of adherences can be felt as a click,
and it denotes the instant return to normal range of
mandibular movement

If however, the adherence remains for a significant
period of time, fibrous tissue can develop between the
articular structures ,and a true adhesion can develop.
This condition represents a mechanical connection
that limits normal condyle-disc-fossa function.
Another cause of adhesions is hemarthrosis (i.e.,
bleeding within the joint). The presence of blood by-
products seems to provide a matrix for the fibrous
unions found within adhesions.
 Hemarthrosis can occur when the retrodiscal
tissues are disrupted by either external jaw trauma or
surgical intervention.

The morphologic characteristics of the surfaces
usually conform to each other closely. If the
morphology of the disc, condyle, or fossa is altered,
joint function can be impaired. For example, a bony
protuberance on the condyle or fossa may catch the
disc at certain degrees of opening, causing alterations
in function.
The disc itself may become thinned (as with disc
displacement) or even perforated, causing significant
changes in function.
These alterations in form can create click-ing and
catching of the jaw similar to that seen with
functional disc displacements.

Subluxation (hypermobility)
Some joint reveal that as the mouth opens to its
fullest extent, a momentary pause occurs, followed by
asudden jump or leap to the maximally open position.
This jump does not produce a clicking sound but
instead is accompanied by more of a THUD.
The examiner can readily see it by watching the side
of the patient's face. During maximum opening the
lateral poles of the condyles jump forward (i.e.,
subluxation), causing a noticeable preauricular
depression.

The cause of subluxation is usually not pathologic.
Subluxation is more likely to occur in a TMJ with an
articular eminence that has a short, steep posterior
slope followed by a longer, flatter anterior slope. The
anterior slope is often more superior than the crest of
the eminence

Spontaneous dislocation.
On occasion the mouth is opened beyond its normal
limit and the mandible locks. This is called
spontaneous dislocation or an open lock
With spontaneous dislocation the patient cannot
close the mouth. Wide opening (e.g., from an
extended yawn or a long dental procedure) almost
always produces this condition.
Spontaneous dislocation typically occurs in a patient
who has the fossa anatomy that permits subluxation.

Concept by Bell
Concept by Kai

Synovitis
Synovial tissues that lines the recess area of the joint
become inflamed.
Characterised by constant intracapsular pain that
enhances with joint movements.

Capsulities
Capsular ligament becomes inflamed.
Tenderness when the lateral pole of the condyle is
palpated.
Pain even in static position but joint movement
generally increase the pain.

Retrodiscities
Inflammation of retrodiscal tissues.
Constant dull aching pain that often increased by
clinching.
swelling may occur and force the condyle slightly
forward, down the Posterior slope of the articular
eminence.
 This sum can cause an acute malocclusion. Clinically
such an acute malocclusion is seen as disengagement
of the ipsilateral posterior teeth and heavy contact of
the contralateral canines

As the disc is thinned and the ligaments become
elongated, the condyle begins to encroach on the
retrodiscal tissues. The first area of break-down is
the inferior retrodiscal lamina,which allows even
more discal displacement. With continued
breakdown, disc dislocation occurs and forces the
entire condyle to articulate on the retrodiscal tissues.
If the loading is too great for the retrodiscal tissue,
breakdown continues and perforation can occur.
With perforation of the retrodiscal tissues, the
condyle may eventually move through these tissues
and articulate with the fossa.

Arthritides.
Joint arthritides represent a group of disorders in
which destructive bony changes are seen.
Osteoarthritis: most common types of TMJ
arthritides represents a destructive process by which
the bony articular surfaces of the condyle and fossa
become altered. It is generally considered to be the
body's response to increased loading of a joints.
surface becomes softened (i.e., chondromalacia) and
the subarticular bone begins to resorb. Progressive
degeneration eventually results in loss of the
subchondral cortical layer, bone erosion, and
subsequent radiographic evidence of osteoarthritis.

Osteoarthritis is often painful, and jaw movement
accentuates the symptoms.
Crepitation (i.e., grating joint sounds) is a common
finding with this disorder. Osteoarthritis can occur
any time the joint is overloaded, but it is most
commonly associated with disc dislocation or
perforation
Although osteoarthritis is in the category of
inflammatory disorders, it is not a true inflammatory
condition. Often once loading is decreased, the
arthritic condition can become adaptive. The adaptive
stage has been referred to as osteoarthrosis

Headache
Otologic signs and symptoms
ear pain
fullness in the ear or ear stuffiness
tinnitus (ear ringing)
vertigo (dizziness)

Management of TMDs and Occlusion. Jeffrey Okeson 5th
edt.
Functional occlusion from TMJ to smile design.
Dawson- 3rd
ed.
Color atlas of TMJ surgeries. Peter Quinn.
DCNA 2007, Jan, vol 51, no. 1 -TMDs and orofacial pain
Temperomandibular disorders – Weldon Bell
TMDs an evidence based approach to diagnosis and
treatment – Danial Laskin

www.indiandentalacademy.com 147

Tmd / dentistry orthodontics

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