Effects of orthodontic & orthopedic treatment on TMJ /certified fixed orthodontic courses by Indian dental academy

Effects of Orthodontic &
Orthopedic Treatment on
TMJ

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Contents
Introduction
History
Major reviews
Physiology of TMJ
Effect of some occlusal conditions
Effect of orthopedic appliances
-growth relativity
-reviews of various orthopedic
appliance effects

Introduction
DO NO HARM
The harmony of the interface between
the teeth ,muscles ,nerves, supporting
tissue, and temporomandibular joint all
must be in balance to provide health
,functional efficiency,esthetics and
stability to entire stomatognathic system

The methods and means of orthodontic
treatment are a factor of the dentist education
and personal preference based on
experience,objectives and skills.the
comparison of cephalometric records ,facial
and dental photographs,as well as the
alveolar –periodontal status are the usual
means of clinical assessment.
the functional component of occlusal
interdigitation has entered the picture more
emphatically in the past two decades

Numerous suppositions ,hypotheses,
and theories concerning the function
and dysfunction of the TMJ and the
total stomatognathic system have been
given ,the recommendations have
ranged from “do nothing” to “do
everything” to prevent or correct
dysfunction and to ensure proper
maxillary/mandibular stability

There continues to be a clash between
the research community and certain
clinicians regarding the relation
between the functioning dentition and
the temporomandibular joints


History
Prentiss & Summa 1918-studied relation
between loss of teeth and jaw dysfunction
and reported pressure atrophy of meniscus
Hildebrand recorded mandibular & condylar
movements in frontal and sagittal plane &
discussed the influence of various food types
on different mandibular movements


Costen 1934 ,described a group of
symptoms associated with marked
overbite or mandibular overclosure
“Costen’s Syndrome”
Shultz 1947, presented a theory that lax
ligaments could result in subluxation
followed by complete luxation

In late 1940s through 1960s ,a
neuromuscular component of normal and
abnormal jaw function began to appear
Schwartz presented the theory that pain
associated with mandibular dysfunction
perhaps had its origin in musculature.pain
could be caused by muscle spasm


Bonica was among the first to describe the
etiology and treatment of myofascial pain
syndrome ,he also described hypersensitive
trigger areas
Later Schwartz concluded that
predisposition ,psychologic as well as
physiologic is more important than the
particular form of the precipitating factor itself

Moulton reported that significant and
complicating emotional factors can be strong
differential diagnosis for facial pain
Laskin 1969,questioned the role of occlusion
in creating symptoms with the exception of
frank iatrogenic factors .his studies supported
the idea that muscle fatigue was the prime
cause of pain

Brodie stressed the importance and
relation of the temporomandibular joints
to orthodontic therapy
Thompson ,one of brodie’s student
studied the clinical importance of the
temporomandibular joints to the
orthodontic specialty

Brodie ,Thompson &Ricketts were the
leaders in the American orthodontic
community in emphasizing the
interrelation of occlusion to the TMJ


Does a malocclusion contribute to or cause
TMD ?
Different groups exist –for it and against it
And some are of the view that certain
orthodontic procedures could produce TMD
symptoms
Some authors concluded as the relationship
of the TMDs to occlusion and orthodontic
treatment is minor

What majority concluded ?
Probable explanation .
Some important correlations.


Some questions to be answered
Does orthodontic treatment lead to a greater
incidence of TMD?
Does type of appliance make a difference?
Does the extraction as part of orthodontic
protocol lead to greater incidence of TMD?
Can orthodontic treatment lead to a posterior
displacement of the condyle?
Does orthodontic treatment prevent TMD?

Effect of orthodontic treatment on TMJ
Studies from mid 1960s onwards
Two studies were done as part of a National
Institutes of Dental Research (NIDR)
research contract on the long-term effects of
orthodontic treatment.
Sadowsky and BeGole reported on the findings
from 75 adult subjects who were treated with
full fixed appliances as adolescents
approximately 20 years previously and
compared them with a similar group of 75
adults with untreated malocclusions.

Another independent study, also part of the
NIDR research contract, performed at the
Eastman Dental Center on 111 subjects who
received orthodontic treatment a minimum of
10 years previously and were compared with
111 adults with untreated malocclusions.
Nonextraction and extraction cases were well
represented in both the above studies.


Findings were
prevalence of symptoms varying between 15% to
21% and 29% to 42% for signs ( joint sounds),
there was no statistically significant difference
between treated and untreated subjects in either of
the studies.
The conclusion from the above two studies was that
orthodontic treatment performed during adolescence
did not generally increase or decrease the risk of
developing TMD in later life.

Larsson and Ronnerman studied 23 Swedish
adolescent patients who were treated orthodontically
10 years previously, 18 of whom had fixed appliances
and 5 of whom had a functional appliance (activator).
In 31% of the subjects mild dysfunction was
recorded clinically and only one subject (4%) had
severe dysfunction recording
. In comparing their results with other published
epidemiologic studies, they concluded that extensive
orthodontic treatment can be performed without fear
of creating complications of TM dysfunction.


Janson and Hasund in Norway studied 60
patients with Class II, Division 1
malocclusions who were treated as
adolescents an average of 5 years out of
retention, 30 of whom were treated with a four
premolar extraction strategy; the 30
nonextraction patients received a
combination of headgear and activator
initially, followed by fixed appliances.
A sample of 30 untreated patients were used
as a control.

. Anamnestic symptoms were found in 42% of
subjects overall (treated and untreated), with
similar findings for the clinical dysfunction
index, which were mostly of a mild-tomoderate degree.
The findings supported the conclusion that
there was not a significant risk of developing
TM dysfunction when treating orthodontic
patients with relatively severe malocclusions

Lieberman et al in a survey of 369
Israeli school children 10 to 18 years of
age,. found no association between
previous orthodontic treatment and
increased symptoms of mandibular
dysfunction


In a prospective longitudinal study, Dibbets and van
der Weele in the Netherlands studied 63 orthodontic
patients who were treated with a modified functional
activator and 72 patients who were treated with fixed
appliances (Begg technique) mostly with an
extraction treatment strategy during childhood and
adolescence.
The patients were followed over a 10-year period. A
subsample of patients at the pretreatment stage
served as an internal control group.


Objective signs increased from 21% to 41% overall;
however, the authors attributed the increase to age
rather than orthodontic treatment on the basis of an
internal control group
. The findings for subjective symptoms, objective
signs and radiographic changes in the condyles
supported the conclusion that orthodontic treatment
does not induce TM dysfunction.
the fixed appliance group as compared with the
functional appliance group had higher percentages of
objective symptoms after retention, no differences
existed at the 10-year follow-up.


Dahl et al. conducted a retrospective study of 51
Norwegian subjects who were 19 years of age and
an average of 5 years after orthodontic treatment.
Signs and symptoms of craniomandibular disorders
(CMD) were compared with 47 untreated 19-year-old
persons. The clinical dysfunction index showed mild
symptoms in 43% and moderate symptoms in 28% of
the treated group and 40% and 13% in the untreated
group. They concluded that there were no substantial
differences between these two groups.


Smith and Freer in Australia examined 87 patients
who received full fixed appliances during
adolescence, approximately two-thirds involving
extractions, and who were an average of 52
months(4.5 years) after retention and compared them
with an untreated control group of 28 subjects.
Symptoms were found in 21% of the treated subjects
and 14% of the controls, which was not statistically
significant
. Their results rejected the hypothesis of a significant
association between orthodontic treatment and
occlusal or TMJ dysfunction.


In a report of a survey of 568 dental students
ages 20 to 43 years at the Medical College of
Georgia, Loft et al. found a significant
association between facial discomfort and
pain as reported by the female subjects only,
who had received orthodontic treatment.


Nielsen et al. evaluated 706 Danish children of whom
295 (37%) had completed orthodontic treatment and
were between 14 and 16 years of age. The 388
untreated subjects served as controls.
Approximately one-third of the subjects had signs of
TM dysfunction.
It was found that the functional status was not related
to the type of orthodontic treatment or the use of
removable or fixed appliances, including extraction
therapy.


According to Thompson faulty intercuspation of the
teeth and dental intrusions into the freeway space are
two of the many etiologic factors that may lead to
joint dysfunction and its sequelae.
Dysfunction of the joints and musculature may occur
before orthodontic treatment, during treatment, or
anytime after treatment has been completed.
Whether related directly to treatment or not, the
orthodontist must be alert to recognize such
dysfunction and intervene whenever it may occur.

If the condyles are not growing upward and
backward at the time of orthodontic tooth
movement, the body of the mandible will not
be projected downward and forward with the
rest of the face, and the normal dental
freeway space can be lost. The result is
downward and backward rotation of the
mandible, which may cause clicking and other
symptoms in the joint.

Additional condyle growth after other
facial growth has stopped is a special
concern because it can alter the
occlusion and joint function. There may
be no joint clicking or other symptoms
at 12 or 14 years of age, yet
pronounced symptoms 5 years later.

in a dental malocclusion with shortened arch length
and insufficient space for canine eruption, the
incisors may be intruding into the freeway space. The
resultant incisal interference can cause posterior
displacement of the mandible with possible clicking of
the joints.
bilaterally narrow maxillary dental arch, as may be
caused by thumb or finger sucking can cause the
mandible to be displaced into a crossbite relation,
often combined with a Class II molar relation on the
side of the crossbite. In this situation, clicking is often
found in the joint on the side of the crossbite


A prospective longitudinal study of 238 subjects in
three different age groups (7, 11, and 15 years) was
conducted over a 4 to 5-year period by EgermarkEriksson et al. in Sweden.
Corrective orthodontic treatment had been done on
35 subjects. Approximately 20% of subjects in the
older age group had clinical signs of CMD. No
differences were found in the prevalence of signs or
symptoms of CMD between orthodontically treated
and untreated subjects.


Dibbets and van der Weele reported the findings
from their prospective longitudinal study in the
Netherlands over a 15-year period for 111 of the
original 172 orthodontically treated patients of the
average age of 12.5 years who were enrolled in the
study.
Removable appliances (functional) were used in
39%, fixed appliances (Begg) in 44%, and chin cups
in 17% of cases. A nonextraction approach was used
in 34% of cases, four premolars were extracted in
29%, and other extractions in 37%.


They evaluated subjectively perceived symptoms,
which increased from 20% to 62%;
objectively identified clicking/crepitation, which
increased from 23% to 36% after 4 years and then
stabilized;
and the radiographic appearance of the condyle,
which increased slightly during the first 4 years and
then stabilized at around 25%.
It was found that during the first years of the study,
age probably accounted for the statistical differences
in percentages between the three types of treatment;


the influence of age disappeared after 10 years. For
the first 10 years there was no difference between
the three treatment groups with regard to subjective
clicking., after 15 years it was greater for the four
premolar extraction group
Objective clicking was always more frequent in the
four-premolar extraction group at all time points,
Clicking frequency, subjective or objective, was
always higher in the four premolar extraction group
even before treatment was started.


They concluded that the original growth
pattern, rather than an extraction treatment
strategy, was the most likely factor
responsible for the frequency of CMD
reported many years posttreatment.


Sadowsky et al. reported on their prospective
longitudinal study of 160 patients of average age of
14 years 6 months (range 9 to 41 years), treated with
full fixed appliances for an average of 35 months
(range 14 to 53 months).
Of the 160 patients, 54% were treated with an
extraction treatment strategy and 42.5% were treated
with nonextraction (3.1% had missing data).
In addition to recording symptoms, joint sounds were
objectively recorded with an audiovisual videotape
system.


Before treatment 25% of patients had joint sounds,
whereas 16.2% had sounds after treatment.
In 27 patients the sounds were not evident after
treatment, in 13 patients there was no change in
occurrence, and sounds developed in 13 patients by
the end of treatment.
The findings did not indicate a progression of
signs/symptoms to more serious problems.
The conclusions were that orthodontic treatment did
not pose an increased risk for the development of TM
joint sounds irrespective of whether extraction or
nonextraction treatment strategies were used.


Lotika Wadhwa,, Ashok Utreja,, and Amrit Tewari,
compared the status of signs and symptoms of TM
disorders in three groups of adolescents and young
adults. The groups consisted of 30 persons with
normal occlusions, 41 with untreated malocclusions,
and 31 with treated malocclusions.
The clinical status and subjective symptoms of TM
dysfunction were recorded The results showed that
the normal occlusion group had the maximum
number of persons free from any dysfunction,


but the differences between the groups in the
distribution of persons according to the anamnestic
and clinical dysfunction indices were not significant.
The only statistically significant finding was the
difference in the clinical dysfunction index scores of
the persons with normal occlusions and untreated
malocclusions. According to anamnesis, the most
frequently reported symptoms were related to periods
of stress.


Among the clinical signs and symptoms, the most
commonly occurring were crepitations on palpation
and sounds on auscultation of the joints in all the
three groups.
In conclusion, the absence of substantial differences
between the three groups indicates that the role of
orthodontic treatment in either precipitation or
prevention of TM dysfunction is questionable.


O'Reilly,. Rinchuse, Close, studied effect of classII
elastic and extraction on TMJ
The experimental group comprised 60 subjects, 30
girls and 30 boys, with a mean age at the start of
treatment of 15.3 years (range 14.3 to 16.1 years).
These subjects received orthodontic treatment with
edgewise straight wire appliances, extractions, and
retraction of the anterior maxillary teeth with Class II
elastics from canines to mandibular second molars.
The teeth extracted were the maxillary first premolars
in 48 patients and the maxillary and mandibular first
premolars in 12 subjects.


The control group consisted of 60 orthodontically
untreated subjects.
The only significant finding in this study was pain
(mild) on palpation "lateral to the TMJ capsule" at the
8- to 10-month period during orthodontic treatment;
this was present for 40% of the orthodontically
treated subjects. There is no logical explanation for
this finding.
this study demonstrated that edgewise straight wire
orthodontic treatment involving extractions and Class
II elastics have no effect, or little effect (i.e., mild pain
"lateral to TMJ capsule"), on TMJ signs and
symptoms.


CONDYLAR POSITION AND
ORTHODONTIC TREATMENT

Orthodontic treatment, particularly involving premolar
extractions, has also been implicated in producing a
posteriorly positioned condyle.
It has been reported anecdotally that an internal
derangement may therefore result.
In a cross-sectional study, Gianelly et al. evaluated
condylar position with corrected tomograms before
orthodontic treatment in 37 consecutive patients ages
10 to 18 years and compared them with 30
consecutively treated four premolar extraction cases
at the completion of treatment.


All patients were treated with fixed appliances, 23
with the edgewise technique and 7 with the Begg
technique.
They could find no difference in condylar positions
between the extraction and the untreated groups. It
was concluded that extraction therapy did not appear
to be an iatrogenic cause of distally positioned
condyles.
Condylar position tended to be centered on average;
a wide variation in position was noted. Similar wide
variations in normal condylar position has been
reported by several authors as discussed by Tallents
et al.


William E. Wyatt,reported
In Class ll malocclusions with deep interlocking cusps
headgear and/or Class 11 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 in to maximum
intercuspation. This compensating movement by the
mandible can put distal pressure on the condyles and
conceivably cause an anterior dislocation of the disk


. Midsagittal section through TMJ. 1, Superior joint space. 2, Cortical
plate of eminence. 3, Superior articulating surface of disk. 4, Articular
surface of eminence. 5, Avascular portion of disk. 6, Articular surface of
condyle. 7, Inferior joint space. 8, Cortical plate of condyle. 9, Fibers of
superior head of lateral pterygoid muscle. 10, Fibers of inferior head of
lateral pterygoid muscle. 11, Bilaminar zone of disk. 12, Elastin fibers
attaching disk to rear wall of fossa (in posterior attachment). 13, Inelastic
distal ligament. 14, Vascular complex (retrodiskal tissue). 15, Auditory
canal. 16, Attachment of distal ligament to condyle.

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 muscles can help to hold
the mandible forward
Lower headgears or reverse headgears that exert
distal pressure on the chin and Class lll elastics are a
very important part of orthodontic treatment, but they
too can put distal pressure on the mandible..


If there is a developing problem, it is better to
have the patient wear lower or reverse
headgear and Class III elastics only during
waking hours. During this period lower or
reverse headgears have little effect on the
TMJ because muscle tone (tension) positions
the mandible forward.


R S Nanda & Carlton 2002 conducted a followup prospective longitudinal study to
determine what changes occurred in the
condyle/fossa relationship after treatment.
Orthodontic posttreatment records, including
corrected tomograms of 106 white patients
(58 Class I and 48 Class II Division 1), from a
pretreatment sample of 232 patients, were
analyzed. The average pretreatment age was
13.6+ 3.0 years. The average length of
treatment was 2.3 years for the Class I
group and 2.8 years for the Class II Division
1 group.

With orthodontic treatment, the condyle
became more concentrically positioned,
There was no statistically significant
correlation between changes in the
condyle/fossa relationship based on age,
gender, skeletal or dental variables, signs or
symptoms of temporomandibular disorder,
headgear use, type of elastics, or
nonextraction vs extraction treatment.

TMJ SOUNDS AND ORTHODONTIC TREATMENT
Temporomandibular joint sounds are a common
finding and occur in approximately 20% to 30% of the
population including patients before orthodontic
treatment.
Wabeke et al. on TMJ clicking in 1989- joint sounds
are the most frequent sign of TMD and are often
present in the absence of symptoms. Treatment to
eliminate joint sounds is usually unsuccessful. In the
absence of pain or significant discomfort, patients
with joint sounds should be reassured and monitored
over time.

Approximately half of the patients with joint sounds
have a reciprocal click, which is often associated with
disk displacement with reduction.
In many patients the reciprocal clicking may be
explained by condylar dislocation anterior to the disk
or the articular eminence. Joint sounds or other
symptoms may change in character or disappear
over time and do not usually progress to joint
degeneration.


PROGRESSION OF SIGNS/SYMPTOMS OF TMD
Wanman and Agerberg studied 258 subjects from 17
to 19 years of age and found no change in symptoms
in 60%, whereas 20% improved, and 20% got worse.
In a study of 70 patients with reciprocal clicking
whose mean age was 30 years (range 10 to 69
years) Lundh et al. found that over 3 years 71%
showed no change, 29% decreased, and 9%
progressed to locking.


Magnusson et al., in following 119 subjects
longitudinally from age 15 to 20 years, found
no change in clinical signs in almost half the
subjects, with almost equal rates of
improvement and impairment.


clicking is generally benign and does not progress to
more serious clinical dysfunction or disease, even in
subjects who previously had symptoms., subjects
with symptomatic clicking can be successfully treated
without addressing the position of the disc
joint sounds alone are not pathognomonic of disease
and may be present for up to 10 years without
progression.
joint sounds do not necessarily indicate a "problem"
but may represent a "risk" factor; however, no
treatment should be considered in the absence of
symptoms.


If painful symptoms arise during
orthodontics, therapy may have to be
modified, gross occlusal interferences
relieved, and forces tending to distalize the
mandible eliminated


Niler &Kulor studied the occlusal changes in girl
subjects with classII malocclusion undergoing
treatment and compared with normal subjects
Orthodontic treatment did not increase the risk for or
worsen pretreatment signs of TMD in a 2 years
perspective
Class II Patients with TMD symptoms before
treatment benefited from treatment
The normal group had lower prevalence of signs of
TMD as compared to orthodontic and untreated
classII groups


Inger Egermark, Magnusson,. Carlsson, 20Year Follow-up of Signs and Symptoms of
Temporomandibular Disorders and
Malocclusions in Subjects With and Without
Orthodontic Treatment in Childhood
402 randomly selected 7-, 11-, and 15-yearold subjects were examined clinically and by
means of a questionnaire for signs and
symptoms of TMDs. The examination was
repeated after five and ten years. After 20
years, 320 subjects (85% of the traced
subjects) completed the questionnaire.

The oldest age group, 35 years of age, was
invited to a clinical examination, and 100
subjects were examined. The correlations
between signs and symptoms of TMD and
different malocclusions were mainly weak,.
Lateral forced bite and unilateral crossbite
were correlated with TMD signs and
symptoms at the 10- and 20-year follow-ups.
Subjects with malocclusion over a long period
of time tended to report more symptoms of
TMD and to show a higher dysfunction index,
compared with subjects with no malocclusion
at all.

There were no statistically significant
differences in the prevalence of TMD signs
and symptoms between subjects with or
without previous experience of orthodontic
treatment.
This 20-year follow-up supports the opinion
that no single occlusal factor is of major
importance for the development of TMD,.
subjects with a history of orthodontic
treatment do not run a higher risk of
developing TMD later in life, compared with
subjects with no such experience.

Mohlin, Derweduwen, Pilley, Kenealy,
examined total of 1018 subjects at the age of 11
years, 791 were reexamined at 15 years, 456 at 19
years, and 337 at 30 years. Anamnestic and clinical
recordings of temporomandibular disorder (TMD)
were made. Morphology, including calculation of peer
assessment rating (PAR) scores, was recorded.
Previous history of orthodontic treatment was
assessed.
The subjects completed four measures. The
malocclusion prevalence, occlusal contacts,
psychological factors, and muscular endurance in
subjects with no recorded signs and symptoms of
TMD were compared with those with the most severe
dysfunction at 19 years of age.

The further development of TMD to 30 years
of age was followed. PAR scores were
significantly higher in the subjects with the
most severe dysfunction. Apart from crowding
of teeth, no other significant differences were
found between the groups with regard to
separate malocclusions, tooth contact pattern,
orthodontic treatment, or extractions.
Significant associations between TMD and
general health and psychological well-being
as well as the personality dimension of
neuroticism and self-esteem were found.

During the period from 19 to 30 years, the
prevalence of muscular signs and symptoms
showed considerable reduction, whereas
clicking showed a slight increase. Locking of
the joint showed a decrease from 19 to 30
years. One-quarter of the TMD subjects
showed complete recovery.
Thus, orthodontic treatment seems to be
neither a major preventive nor a significant
cause of TMD.

Probable Explanation


TMJ = ginglymoid diarthrodial joint
Ginglymoid =hinge movement
Diarthrodial =discontinous articulation
that permits greater freedom of
movement
It is a simple type of synovial joint


Functional demands require extensive
movement
The articulating surfaces must be
completely disconnected yet firmly held
in place
Therefore articulating surfaces are
composed of tissue that is neither
innervated nor vascularized

In absence of vasculature ,nutritional
and metabolic activities must be
provided for by way of a special joint
fluid that is supplied by vessels free
from interarticular pressure
Encapsulation is required to contain the
joint fluid –synovial fluid

The disconnected bones of synovial joint are
supported by
1. system of ligamentous structures that
passively limit the amount of separation
permitted by the articular surfaces and that
restrain the degree and direction of joint
movement
2. a system of skeletal muscles that actively
hold the parts in sharp contact during all
functional activities and that furnish power
for working movements

Encapsulation –fibrous capsule is attached
near the periphery of the articular surface
Capsule is well vascularized and innervated
The vessels supply tissue fluid which has free
metabolic interchange with the synovial fluid
within joint cavity
Synovial membrane that secretes the fluid
lines the inner surface of fibrous capsule

It also serves as a joint lubricant and
shock absorber
Capsule is innervated with nociceptors
with a high threshold, so that pain is
usually not felt unless the strain
,distortion, or distension is considerable


Articular surfaces
Noninnervated ,nonvascularized
articular tissue in most synovial joints is
hyaline cartilage ,but in TMJ it is slightly
different from hyaline cartilage ,it is
more of fibrous nature


Retrodiscal tissue
Highly vascularized tissue it is the main source
of synovial fluid to both compartments of the
TMJ
Any damage at retrodiscal tissue will be
manifested at articular surface of the joint


Weeping lubrication
Described by DuBrul
Under all non compressive situations the
articular tissue takes up synovial fluid
Under compressive force ,this fluid is
expelled onto the surface in tiny droplets and
forms a layer of liquid that acts as a
lubricating film
Articulating surfaces may be moved under
pressure without sustaining damage

This effect makes extensive joint
movement ,even under considerable
pressure harmless to the joint
But when all the fluid is expelled out ,further
movement is without adequate lubrication
,and resultant friction is potentially damaging
to the articular surfaces


3 factors are important
Length of time
Degree of pressure
Extent of movement


Momentary high pressure even with
extensive movement is harmless as
well as limited sustained pressure
without movement


Boundary lubrication
it pertains to the reservoir of synovial fluid
in the joint cavity which lubricates the articular
tissues by surface contact and is the means
of replenishing that which enters into the
weeping lubricating mechanism
When synovial fluid becomes too viscid its
lubricating qualities are seriously impaired –
Gelation

Interarticular pressure {passive & active}
Passive
It provides continuous sharp contact of the
articulating surfaces in the resting joint and
during unstressed movements.It results from
muscle tonus as affected by gravitational
force which varies with posture.
It also varies with emotional stress ,tension
,activities ,fatigue,time of day,age and illness

Active
It results from the contraction of skeletal
muscles as required to overcome resistance
and accomplish the intended task –the
stresses and forces of musculoskeletal
activity
It is extremely variable


Loading
It refers to the effect of active interarticular
pressure on the joint surfaces due to muscle
action as affected by resistance
Proteoglycans found in the collagen matrix of
superficial layers of articular tissue is a
measure of resilience of that tissue and is
indicative of location and degree of loading

Overloading
static
dynamic


Remodeling –if overloading occurs at a
tolerable rate
Degeneration –if the requirement for
change exceeds the capability of the
articular surface to remodel
,degenerative changes may occur


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

Important question that still remains is how
this minor contribution can be identified within
the population of TMD patients
The key word is to reach to an accurate
diagnosis before any treatment is begun
Then only a treatment regime should begin to
deal with each specific signs and symptoms


For orthodontic patients all the pretreatment
records and documenting ranges of
motion ,muscle tenderness,evidence of joint
sounds, locking or irregular movements and
patients subjective location of percieved pain
are to be recorded
Always avoid promising the patient that you
will relieve the signs and symptoms with
treatment

Precipitating factors of TMD symptoms
can be dental procedures including
orthodontic extra and intra-oral
appliances as well as mechanics which
result in inadvertent and rapid occlusal
table alteration


the benefits of orthodontic treatment in
the management of temporomandibular
disorders (TMD) is questionable, since
the occlusion is considered as having a
limited role in the cause of TMD as
recently stated by Seligman and
Pullinger.

Pullinger and associates applied multiple
factor analysis which indicated the low
relation of occlusion to TMD ,some of the
factors having a slight relationship are
Apertognathia
Overjet more than 6-7mm
CR-CO discrepancy more than 4mm
Unilateral lingual crossbite
Five or more missing posterior teeth

Anterior open bite –predominantly associated
with osteoarthrosis and myalgia
For an anterior open bite to be etiological
factor in for arthrosis ,some evidence of
preceding derangement should be present
that will lead to arthrosis
It is hypothesized that the tendency to
develop anterior open bite in osteoarthrosis is
a consequence of and secondary to condylar
osseous changes instead of etiology

TMJ condylar changes should be ruled
out in any adult patient presenting with
anterior open bite or rapid bite changes


Overjet –overjet more than 5 mm is
associated with myalgia and arthrosis
It is also considered a effect rather than
etiology


Unilateral posterior maxillary lingual
crossbite
Considered as most common type of
crossbite
Individuals have a greater risk of
internal derangement of the TMJ


Functional unilateral crossbite in childhood
produces a displacement of the mandible
resulting in right to left side differences in
condyle fossa position at intercuspal position
This leads to functional adaptation in the TMJ
,but in some individuals it is less than optimal
and might be accomplished at the expense of
the articular disc by development of internal
derangement

Skeletal crossbite in adults does not
appear to provoke TMJ
symptomatology or disease


Posterior tooth loss
There is a increased likelihood of
patients with posterior tooth loss
belonging to disease group (disc
displacement and arthrosis )
A minimum of 5 posterior teeth need to
be missing for correlation

Missing 2 or 4 premolars for orthodontic
treatment had minimum contribution
that is negligible


CR-CO discrepancy –discrepancy of
about 1mm is almost seen in all groups
Slides more than 2mm may accompany
intracapsular problems
For more serious derangments to occur
a slide of 5mm may have to be present


Studies fail to demonstrate any association
between occlusal interferences and TMD
signs or symptoms
Because contribution of occlusal slides is
minor ,prophylactic elimination of slides
through coronoplasty is difficult to support
Even in the presence of symptoms removal of
larger slides could be ill-advised until
diagnosis is clarified ,because the slide may
be consequence of TMJ articular disorder

Although contribution of occlusal
features is not zero ,the importance
should not be overstated ,since this
may lead to neglect of many other
causes of orofacial pain and
dysfunction in a biologically
multifactorial system

Effect of orthopedic treatment
Mandibular advancement appliances
- Herbst,twin block,frankel etc
Headgears
Chincup


It was previously thought that increased
activity in the postural masticatory muscles
was the key to promoting condyle-glenoid
fossa growth.
3 conditions that often overlap:
normal condyle-glenoid fossa (CGF) growth,
orthopedic remodeling as a result of condylar
advancement,
pathosis at the condyle.

Pathologic adaptations , show the C-GF
region’s ability to be modified significantly.
This type of growth is distinctly different from
the limited short term growth modification
observed with orthopedic displacement
therapy.


HOW CONDYLAR MODIFICATIONS OCCUR
the genetic theory, suggests the condyle
is under strong genetic control like an
epiphysis that causes the entire mandible to
grow downward and forward.
this may be related more to development of
the prenatal than postnatal condyle, the
theory does indirectly question the
effectiveness of orthopedic appliances in
condylar growth

long-term investigations actually showed
clinically insignificant condylar growth
modification after continuous mandibular
advancement with a reasonable retention
period in human.
general growth of the condyle appears
relatively unalterable in long-term studies.


LATERAL PTERYGOID
HYPERACTIVITY HYPOTHESIS
The LPM hyperactivity theory brought forward
by Charlier et al, Petrovic, and later
McNamara, It suggests that hyperactivity of the
lateral pterygoid muscles (LPM) promotes
condylar growth.
. Attachments of the LPM to the condylar
head or articular disk may be expected to
cause condylar growth,

Anatomic research has not found
evidence that significant attachments
actually exist
The LPM tendon is observed attaching,
to the anterior border of the fibrous
capsule that attaches to the fibrocartilage
of the condylar head and neck anteriorly
Recently , permanently implanted
longitudinal muscle monitoring
techniques have found that the condylar
growth is actually related to decreased
postural and functional LPM activity.


The functional matrix theory,
The principal control of bone growth is not
the bone itself, but rather the growth of soft tissues
directly associated with it.
this was supported in part by investigations testing
the different growth and developmental responses
between the condyle and epiphysis,
there has been no explanation as to exactly how
condylar growth would be stimulated. Thus, this
theory’s validity has been questioned.


GROWTH RELATIVITY HYPOTHESIS
Growth relativity refers to growth that is relative
to the displaced condyles from actively relocating
fossae.
Three Main Foundations
The glenoid fossa promotes condylar growth
with the use of orthopedic mandibular
advancement therapy.
displacement affects the fibrocartilaginous
lining in the glenoid fossa to induce bone
formation locally

This is followed by the stretch of nonmuscular
viscoelastic tissues.
Third is the new bone formation some distance from
the actual retrodiskal tissue attachments in the fossa
The glenoid fossa and the displaced condyle are both
influenced by the articular disk, fibrous capsule, and
synovium, which are contiguous, anatomically and
functionally, with the viscoelastic tissues., condylar
growth is affected by viscoelastic tissue forces via
attachment of the fibrocartilage that blankets the
head of the condyle

viscoelasticity addresses the viscosity and
flow of the synovial fluids, the elasticity of the
retrodiskal tissues, the fibrous capsule and
other nonmuscular tissues including LPM
perimysium, TMJ tendons and
ligaments,other soft tissues, and bodily fluids.


Microscopic examination of TMJ- revealed
direct connective tissue attachments of the
retrodiskal tissues into the unique
fibrocartilaginous layer of the condylar head .
This fibrocartilage that caps the condyle in 3dimensions is not found on epiphyses.


During orthopedic mandibular
advancement, there is an influx of
nutrients and other biodynamic
factors into the region through the
engorged blood vessels of the
stretched retrodiskal tissues that
feed into the fibrocartilage of the
condyle. This gives rise to
metabolic pump-like action of the
retrodiskal tissues.


. This TMJ pump may initially act similar to a
suction cup placed directly on the displaced
condylar head to activate growth.
The negative pressures, initially below
capillary perfusion pressures, permit the
greater flow of blood into the C-GF region
This increases the flow to the synovial
capillaries near the condyle and the fossa.

The concept suggests that -modification first occurs
as a result of the action of anterior orthopedic
displacement.
Second, the condyle is affected by the posterior
viscoelastic tissues anchored between the glenoid
fossa and the condyle, inserting directly into the
condylar fibrocartilage.
Finally, it is hypothesized that displacement and
viscoelasticity further stimulate (or turn on the light
switch for) normal condylar growth by the
transduction of forces over the fibrocartilage cap of
the condylar head


The increase in new endochondral bone
formation appears to radiate as
multidirectional finger-like processes beneath
the condylar fibrocartilage, and significant
appositional(periosteal) bone formation is
seen in the fossa


Growth restriction of glenoid fossa
Popovich and Thompson in healthy patients from the
Burlington Growth Center, have found that the
glenoid fossa grows in a posterior and inferior
direction.
the anterior slope of the articular eminence
undergoes extensive resorption in a posterior and
inferior direction and the posterior slope undergoes
compensatory endosteal deposition until 7 years of
age.


The condyles and fossae in individuals with average
FMA grow generally in a posterior and inferior
direction based on the cranial base superimposition.
the fossa is reported to grow in the reverse direction,
relocating anteroinferiorly to meet active condylar
modification and to restore normal function during
orthopedic treatment. This is a relative restriction of
normal fossa growth, and it contributes toward Class
II correction.


Epiphysis Versus Condyle
the condyle appears to act like a light bulb on
a dimmer switch. It lights up during
advancement, dimming back down to near
normal levels in retention. Its growth potential
diminishes with age, whereas the glenoid
fossa remodeling “lighting” potential lasts long
into adulthood


Several investigations of relapse have said that C-GF
growth modification cannot be maintained.
. This does not prove, however, that growth of the condyle
is strongly predetermined by genetic factors, like an
epiphyseal growth center. The condyle can restore its
relational position within individual limits.


The tissue-separating force of the epiphyseal growth
center, is a main factor in determining length of long
bones. epiphyseal cartilage has relatively little
adaptive potential over the short-term and has no
fibrocartilaginous cap.
In contrast, the condyle does not have significant
tissue-separating force and is dissimilar to the
epiphysis functionally, anatomically immunologically,
chemically, ontogenetically, or phylogenetically.
Condylar cartilage is capable of both a degree of
healthy intrinsic growth and significant adaptive
growth with short-term mechanical stimulation.


Does Bite-Jumping Damage the TMJ?
Due to the interference of the Herbst
appliance with normal stomatognathic
function, bite-jumping has been blamed of
causing TMD.
A report by Foucart et al in which 3 of 10
Herbst patients developed a disc
displacement in 1 or both joints during
treatment.

Pancherz evaluated the effects of the Herbst
fixed functional appliance in the treatment of
22 growing patients with Class II, Division 1
malocclusions
reported that the number of subjects with
tenderness to palpation doubled during the
initial 3 months of treatment.
after appliance removal, most muscle
symptoms disappeared and 12 months
posttreatment the number of subjects with
symptoms was the same as before treatment.

In a study done by Pancherz & Ruf on 62
consecutively treated Class II malocclusion it
was found that
A temporary capsulitis of the inferior stratum
of the posterior attachment was induced
during treatment.
during the period from before treatment to 1
year after treatment, bite jumping with the
Herbst appliance: (1) did not result in any
muscular TMD

(2) reduced the prevalence of capsulitis and
structural condylar bony changes,
(3) did not induce disc displacement in subjects with
a normal pretreatment disc position
(4) resulted in a stable repositioning of the disc in
subjects with a pretreatment partial disc displacement
with reduction;
(5) could not recapture the disc in subjects with a
pretreatment total disc displacement with or without
reduction .A pretreatment total disc displacement with
or without reduction did not, however, seem to be a
contraindication for Herbst treatment.


In another study long-term effects of the
Herbst appliance on the temporomandibular
joint were assessed in 20 patients (10 girls
and 10 boys) who had completed treatment
an average of 4 years previously. The TMJ
analysis comprised of:
The results revealed that the incidence of
clinical signs and symptoms of
temporomandibular disorders was within the
range of “normal” reported in the literature.
The frequency of disk displacement was not
higher than in asymptomatic populations.

Major limitation of the study was that
pretreatment status of TMJ condition
was not known


Effect of Chin Cup Therapy
Posterior displacement of the condyle may be
expected to occur with chin cup therapy that
may displace the disc anteriorly ,but this has
not been documented yet
During active treatment TMJ pain is the most
significant symptom
This pain could be attributed to local muscle
dysfunction due to deranged posterior
occlusion

In the retention phase TMJ sounds are
more common and pain reduced
drastically
If the chin cup therapy is 6 months or
shorter the symptoms vanish faster as
compared to longer treatment time


Study of temporomandibular joint
laminagraphs indicate that chincup-treated
subjects show significant forward bending of
condyle, deepened-widened glenoid fossa,
and decreased space between the condyle
and fossa in comparison with those of nonchincup subjects.
Another study concluded that chin-cup
therapy may improve not only Class III jaw
relationship but also change TMJ

It was found that a force direction to the
condyle induced a higher compressive
strain at the medial surface of the
condylar head and tensile strain on the
distal surface, and also supported a
possibility of decreased angle of the
mandible.

Arat,. Akcam, and H. Gokalp studied long term
effects of chin cup therapy on a treatment group of 32
patients with skeletal Class III malocclusion treated
with chincup therapy. The mean age of this group
was 18.4 years (range, 13.9 to 22.5 years). The
mean postretention follow-up period was 5.6 years
(range, 2 to 11 years), and the average treatment
time was 1.8 years.
The findings were compared with 2 control groups—
an untreated skeletal Class III control group
comprising 39 subjects (20 male, 19 female), mean
age 15.5 years (range, 12.5 to 31.1 years), and a
normal occlusion control group consisting of 53
subjects.

A functional examination was conducted on
all subjects. Those with at least 1 sign or
symptom (clicking, pain, or deviation) were
identified as the “symptomatic” subgroup.
The results of the study showed that chincup
therapy is neither a risk factor for nor a
prevention of TMD.


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