In reality, T.M.D. has been reported to occur in
35% of all children in America under twelve years
of age.There is also abundant evidence in both the
dental and medical literature that incorrect
restoration and orthodontic procedures can
complicate and even initiate severe T.M.D.
The objective of the presentation is to teach the
clinician to first recognize and properly diagnose
the various stages of T.M.D.Second, to stabilize
the T.M.J.’s and eliminate the systemic side
effects such as pain and vertigo.And third, to
permanently stabilize the case with T.M.J.
orthodontics, reconstruction, equilibration or a
combination of these procedures.
Let us first address the question of
diagnosis.All T.M.D. patients should be divided
into two basic classifications.These are internal
derangement cases and external derangement
cases.The internal derangement case simply means
that there is a mechanic problem within the T.M.J.
capsule. The external derangement indicates that
there is a problem within the muscle-skeletal
system outside of the T.M.J. capsule. Another type
of classification is intra-capsular and
extra-capsular dysfunction.All external
derangements are the result of internal
derangements with the exception of problems such
as an abscess within the muscle, direct trauma to
musculo-skeletal complex, or neuro-muscular
problems such as Meniere’s syndrome – these are
unique situations that should be treated as
independent problems.Therefore the side effects of
most T.M.D. external derangement cases should
subside when the internal derangement is correctly
addressed.
At this point, it is appropriate to discuss
normal T.M.J. function before we address any
pathology. First, there should be no opening or
closing deviations of the mandible. There should
be no noise or pain when the mandible is extended
through a full range of motion.Normal vertical
opening should be at least 50mm from centric
relation. Normal lateral excursion should be 12mm
to 15mm per side when the skeletal midlines are
correctly aligned at an edge-to-edge relationship
of the incisors.
Internal Derangements
Internal derangements are sub-divided into two basic
categories. There are self-reducing and non-reducing
anterior displacements of the meniscus.The
self-reducing anterior displacement of the meniscus
means that as the patient begins to open their mouth
the mandibular condyle is trapped distal to the
meniscus relative to the articular surface of the
glenoid fossa. As the patient continues to open,
tension builds within the joint capsule. At some point
in the opening process, then tension within the
capsule is sufficient to point in the opening process,
the tension within the capsule is sufficient to pull
the head of the mandibular condyle into its correct
position upon the meniscus. From that point onward,
the T.M.J. function is normal because the condyle and
meniscus are operating correctly as a unit.
There are two basic clinical observations that
confirm the diagnosis of a self-reducing anterior
displacement of the meniscus. First, there is an
opening deviation of the mandible ipsy lateral to the
joint problem.As the condyle relocates itself properly
upon the meniscus, the mandibular deviation returns to
normal.When the problem is bilateral, the opening
deviation of the mandible is sigmoid deviating from
side to side and returning to correct alignment,
depending upon which joint complex returns to normal
function first.
The second very diagnostic clinical characteristic is
an audible pronounced sound within the joint capsule
which usually presents itself as a “click”. This sound
is generated by the mandibular condyle relocating
itself correctly upon the meniscus.The earlier this
“click” occurs the less serious is the damage within
the joint capsule.So an “early” click will be much
easier to treat than a “late” click. It is possible
for the patient to develop a closing click, also
called a reciprocal click.This noise is generated by
the mandibular condyle sliding off of the meniscus and
striking the genoid fossa, and usually presents itself
as a dull “thud”.
The self-reducing anterior displacement of the
meniscus will have a full range of normal motion. Very
simply, at some stage in the opening cycle, one or
both mandibular condyles return to their correct
relationship with the meniscus, and from that point
onward, function is totally normal.
The anterior self-reducing displacement of the
meniscus is usually best treated with an anterior
repositioning orthotic.These devices are commonly
referred to as “pull forward splints” and can be
placed on either the upper or lower arch depending
upon the individual malocclusion. We shall discuss the
details of the splint therapy later in this
presentation.
If the damage to the joint complex continues, most
patients advance into what is called a non-reducing
anterior displacement of the meniscus. This means that
no matter how hard the patient attempts to open their
mouth, or manipulate their mandible, the mandibular
condyles remain trapped distal to the meniscus.
The clinical ramifications are obvious.The patient
will have an opening deviation of the mandible ipsy
lateral to the problem with no return to a normal
skeletal midline.They are usually able to obtain the
normal 50mm or more of bite opening, but the opening
is displaced obliquely ipsy lateral to the
derangement. When the problem is bilateral, there is
no significant opening or closing deviation of the
mandible, but the patient will have limited vertical
opening. This limitation will be less than the normal
50mm but not less than 30mm. This is very important
because if the vertical opening is less than 30mm the
patient is in the acute phase if an external
derangement problem irregardless of the internal
derangement.We will address this problem later in our
discussion.
Another key diagnostic test is to align the skeletal
midlines and check the patient’s lateral motion. There
will be limited lateral excursion to the side
contra-lateral to the non-reducing anterior
displacement of the meniscus. The limitation of the
lateral excursion is bilateral when the non-reducing
displacement of the meniscus is bilateral. The limited
movement is usually 5mm to 7mm.
There is no joint noise when the patient has the
non-reducing anterior displacement of the meniscus
since the condyle is unable to “snap” into its correct
position on the meniscus. The joint noise has stopped.
Therefore a patient who reports that their joint
clicked at one point in time and has now stopped
clicking has probably passed from the self-reducing
into the non-reducing stage of the dysfunction.
The non-reducing anterior displacement of the
meniscus is usually best treated with a pivot-splint.
The pivot splint must be placed upon the lower arch.
We will again discuss the pivot splint later in the
presentation.
The most complicating factor in treating T.M.D.
patients is the effect of the external derangement on
the diagnostic procedure.Simply stated, the muscles
attempt to keep the mandibular condyles correctly
positioned on the meniscus when the patient is in full
occlusion.When the malocclusion prevents the correct
condyle relationship the muscles attempt to compensate
the problem by trying to hold they condyle in its
proper position.As they are unable to do so they can
go into a condition of continued contraction know as a
state of hyperactivity.The muscle primarily
responsible for maintaining the correct
condyle-meniscus relationship is the lateral head of
the pterygoid.
Eventually other muscle groups, such as the massiter
and the temporalis, attempt to assist the lateral head
of the pterygoid and they also begin to undergo a
state of hyperactivity. This condition when one muscle
group attempts to support another muscle group is
known as “muscle splinting”.This muscle splinting in
turn can cause severe head, neck and back pain.
>This muscle hyperactivity, the external
derangement, is always present as a result of the
internal-derangement and usually remains at a chronic
level clinically.This means that the patient can have
any number of head and neck muscle sore and eliciting
pain, but the muscles do not prevent normal mandibular
motion.If the hyperactivity of the muscles become
extreme, the patient passes into the acute phase of
the external derangement.At this point the patient’s
vertical opening is limited to 30mm of less. In most
acute phase they cannot even separate their teeth.
The acute phase of the external derangement can occur
at any stage in the internal derangement. It is
sometimes seen at the very early stages of the
dysfunction when the condyle simply slides on and off
of the meniscus, to the extreme internal derangement
that is non-reducing.This acute external derangement
is primarily dependant upon the individual patient’s
systemic physiology which includes oestrogen level,
inter-cellular magnesium level and cell wall poisoning
created by agents like nicotine and caffeine.
The acute phase of the external derangement creates a
very difficult diagnostic situation. Since this
condition can occur at any point in the internal
derangement sequence, it can make diagnosis of the
internal derangement impossible. The logical treatment
procedure is to convert the acute phase of the
external derangement to the chronic phase, then
correctly diagnose the internal derangement.The flat
plane splint is best suited to treat the acute phase
of the internal derangement.This splint can be placed
on either the upper or lower arch, and will again be
discussed in detail further in the presentation.
Let us now discuss the sequence of T.M.D. and its
treatment as it progresses from the child to the
mature adult. In doing so, we will start with the
typical skeletal class II – Division Two malocclusion
which is the most common cause of T.M.D. This type of
malocclusion holds the mandibular condyles back and
possibly up depending upon the posterior vertical
dimension.
In the early years of the disease the upper arch can
be developed sagittally and transversely. This
relieves the entrapment of the maxilla upon the
mandible and the condyles spontaneously relocate into
their proper position on the meniscus. This is known
as “tracking”.This tracking can also occur on an adult
T.M.D. patient depending upon the damage that has been
created within the joint complex. Many clinicians
treat a skeletal Class II – Division two by first
developing the maxilla, which is the correct therapy,
and they note the mandible moving forward towards a
Class I relationship. They assume that the mandible is
growing forward, translation, when they are actually
observing the mandibular condyles tracking.
As the disease process progresses, the patient
masticates with the condyles incorrectly pushed back
on the meniscus.The smooth biconcave form of the
meniscus begins to distort and erode. And, over a
period of time, the mandibular condyles no longer
track into their proper position on the meniscus.This
condition is known as an anterior displacement of the
meniscus when the patient is able to relocate the
condyle on the meniscus the condition is self-reducing
and is treated with anterior mandibular repositioning
orthotic sometimes referred to as a pull forward
splint.
The Anterior Mandibular Repositioning Splint
The A.M.R.S. can be placed on either the upper or
lower arch. The construction bite is taken at an
edge-to-edge relationship of the upper and lower
incisors with a 4mm vertical thickness between the
incisors.This routine mandibular position is
sometimes modified through clinical experience,
transcranials radiographs, and electro-myography,
but it is a very practical starting position for
most T.M.D. patients suffering from self-reducing
anterior displacements of the meniscus.
The acrylic covering all of the teeth is fully
indexed to allow the patient only vertical motion.
This is an extremely important point. If the
patient is wearing a pull forward splint, there
should be no rotary motion of the mandible when
the patient is in full occlusion. Any rotary
motion will irritate the lateral head of the
pterygoid muscle and make the external derangement
more acute.
This is the point in the treatment when the use
of muscle relaxants, hot and cold packs, and the
Alpha-Stim can of great value. Anything that
reduces muscle splinting, myofibril neuroalgia and
hyperactive muscular contraction aids in the
treatment of the external derangement. The key to
using the pull-forward splint is to understand
that the lateral head of the pterygoid muscle can
pull the meniscus off of its correct position on
the articular surface of the mandibular condyle.
These muscles must be totally passive before the
splint is adjusted to allow for rotary motion.
Sometimes the patient’s external derangement will
not subside at the standard edge to edge, 4mm
mandibular position. If this occurs, the clinician
should increase the vertical dimension of the
A.M.R.S. splint by approximately 2mm and the
forward repositioning by 2mm. The re-setting of
the splint should be made every 7-14 days until
all external derangement has been eliminated. All
of the side effects of the T.M.D. problem should
have been totally corrected at this point in the
treatment as well.
Once the lateral heads of the pterygoid muscles
have become passive the full indexing is adjusted
to allow for forward and lateral excursion of the
mandible. The acrylic holding the mandible forward
is not removed. Thus the patient can chew in a
rotary motion in the A.M.R.S. with the condyles
held forward and down in their correct
relationship with the menisci.
Active therapy can now be initiated such as upper
and lower arch development and the use of a
reverse pull headgear. It is also possible to
place a permanent orthotic at this point in order
to stabilize the mandibular condyles.
The Pivotal Splint
The pivotal splint is used to treat the
non-reducing anterior displacement of the
meniscus. This orthotic should always be made on
the lower arch and usually is nothing more than a
flat plane splint.
The pivot is created by adding composite to the
mesial lingual cusp of the maxillary first molar.
This composite should be thick enough so that it
is the only point of contact in the quadrant no
matter how hard the patient bites. If the first
molar is missing the second best point to create
the composite pivot is the mesial lingual cusp of
the maxillary second molar. Should that tooth be
missing also, then the pivot can be placed on the
lingual cusp of the maxillary second bicuspid.
Should the patient be edentulous distal to the
maxillary first bicuspid, an artificial pivot
should be created in the area of the maxillary
first molar by constructing some type of removable
prosthesis.
If the non-reducing anterior displacement of the
meniscus is unilateral the pivot is made
unilaterally with the opposite side constructed
with flat plane occlusion. The patient must eat in
the pivotal splint until the displacement becomes
self-reducing. At that point the patient is
immediately placed into a pull-forward splint and
treated in the appropriate sequence.
Sometimes the pivotal splint does not create a
self-reducing anterior displacement of the
meniscus. These patients require either manual
manipulation of the mandibular condyles or surgery
to secure the correct condyle-meniscus
relationship.
The Flat Plane Splint
The primary use of a flat plane splint is to treat
the acute phase of an external derangement
problem. During this acute phase the muscles of
mastication are in a hyperactive stage and prevent
the correct diagnosis of the underlying internal
derangement. The objective is to allow the acute
external derangement to become passive so that the
appropriate internal derangement orthotic can be
fabricated.
The flat plane splint is usually best tolerated
by the patient when it is placed on the lower
arch. However, it can be placed on the upper arch
when mechanics dictate. Minimum thickness for the
occlusal acrylic is 1.5mm clearance between the
most posterior teeth.
The splint should be adjusted so that all
posterior teeth are in balanced contact no matter
how the patient occludes. This allows the
hyperactive musculature a chance to rest and
become more passive.
If the flat plane splint is placed on the upper
arch it is very critical that there is no lower
cuspid guidance into the acrylic. This principle
applies to any appliance on the upper arch that
utilizes occlusal coverage of acrylic that has
been adjusted flat plane such as a Schwarz
appliance.
Sometimes the patient’s acute external
derangement is so severe that they are unable to
open their mouth to make an impression for
fabrication of the splint. In this situation a
temporary splint should be constructed chairside
using the crown and bridge acrylic. As the
treatment progresses and the patient gains more
vertical opening, a more accurate flat plane
splint can be made using models.
There are a number of clinical points that are
critical for successful splint therapy. These
include:
-
The patient must eat with the splint in place
-
The patient must not bite their teeth together
when the splint is removed for hygiene.
-
The patient should eat relatively soft food
placed on the posterior teeth.
-
The patient should not incise with the front
teeth
-
The patient must not open their mouth
excessively wide.
The general health of the patient is a critical
element in the success or failure of T.M.D.
therapy. Basic nutrition must include a daily
multiple vitamin as well as 1,000 mgs. of Vitamin
C twice a day, 1,000 mgs. of Vitamin E once a day
and chelated magnesium.
In addition, the patient must eliminate all
caffeine from their diet, limit their consumption
of alcohol, and refrain from using any tobacco
products. It is very important that the clinician
assists the patient in making these changes in
lifestyle.
Oestrogen plays a critical role in the patient’s
ability to compensate for T.M.D. This is the
reason the acute phase of T.M.D. is observed more
frequently in the female patient. Oestrogen, via
the parasympathetic nervous system, effects blood
flow to the tempro-mandibular joints. This in turn
reduces the patient’s ability to repair the damage
caused within the joint capsule.
A lack of oestrogen effects cell wall
permeability of magnesium. Magnesium is the trace
mineral involved in the production of synovial
fluid. Therefore the female patient experiences a
dramatic reduction in synovial fluid which
obviously means that the joints have less
lubrication.
Reduced oestrogen levels lower the pain threshold
of the patient and makes them more sensitive to
discomfort. This results in the female patient’s
reduced ability to tolerate the various side
effects associated with T.M.D. Therefore, all
female patients should be evaluated by their
physician for oestrogen maintenance therapy.
Phase Two – Stabilization
Once all external and internal derangements have
been resolved the patient is ready for phase two
treatment, stabilization of the occlusion, the
most common is T.M.J. orthodontics.
T.M.J. orthodontics usually involves three basic
steps. First the arches must be properly developed
to insure that all entrapment of the maxilla upon
the mandible is totally eliminated.
The second step involves transferring the splint
position to a finishing orthodontic appliance.
This is typically accomplished by using an
anterior bite ramp to hold the forward position of
the mandible and composite build up on posterior
teeth to support the vertical direction.
The third step usually entails the placement of
fixed orthodontic appliances to finalize the
occlusion to co-ordinate with the correct position
of the mandibular condyles on the menisci. The
third step is sometimes accomplished by using
finishing splints that allow the teeth to
passively erupt into their correct relationship.
The severity of the malocclusion and economics
must be considered when making a final decision on
finishing the case.
The second most common solution to phase two
stabilization is reconstruction. The same
principles apply in that the mandibular condyles
must be supported horizontally and vertically
until the final fixed or removable reconstruction
is placed.
A third option is a permanent splint. These are
usually made of chrome-cobalt and are simply
exchanged for the acrylic splint. The permanent
splint is frequently the best option for the
geriatric patient or when economics is the primary
concern of the patient.
Sometimes the difference between the patient’s
original occlusion and the desired final occlusion
is very minimal. These cases lend themselves quite
well to equilibration as a solution to final
stabilization.
In some situations the patient’s original
occlusion was not the cause of the T.M.D. problem.
A classic example of this is the trauma created by
whiplash injuries in automobile accidents. These
cases are treated by using the same splint therapy
to allow the joint complex to “heal”, then slowly
removing the acrylic stops that are supporting the
mandible forward and down. This technique is known
as a “walk-back” procedure and must never be used
if the patient’s original malocclusion was the
underlying cause of the T.M.D. problem. The Tanner
type splint is ideally suited for this walk-back
technique.
It should be obvious at this point that correct
diagnosis of the actual cause of T.M.D. is
critical in its treatment. Minimal diagnostic
records should include:
-
Medical and dental history
-
Clinical examination
-
T.M.J. radiographs
-
Cephalometric analysis
-
Mounted study cast analysis
-
Extra-oral and intra-oral photographs
-
Panoramic radiograph
Additional diagnostic aids:
-
Sacro-cranial evaluation
-
Jaw tracking machines
-
Recording the level and type of joint sounds
-
Electronic evaluation of the musculature
The clinician should have a very strict protocol
that allows for thorough evaluation and diagnosis
of each T.M.D. patient. The enclosed examination
form is an excellent guide to successful T.M.D.
therapy.
Summary
In summary, it is best to divide each T.M.D. case
into three distinct categories. First, diagnose
the external and internal derangements that are
the cause of the problem. Second, select the
appropriate orthotic to treat the problem. Third,
stabilize the case in the appropriate fashion.
Following these simple steps will allow the
clinician to successfully treat the vast majority
of patients suffering from T.M.D. and all of its
related side effects.
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