to treat the muscular disturbance in TMJ dysfunction
Note: the deep overbite prevents the mandible from moving forward
during swallowing. The "hollow out" or "sink
in" effect on the posterior restorations and the buccal
prominence of the mandibular alveolar bone indicates the clenching
nature of patient.
Note: the splint design does not include the mandibular anterior
coverage. This will help tremendously in patient compliance
and speech. Upon functioning, there should be only one point
contact bilaterally on the posterior portion of the splint.
This will allow the mandible to "rock" forward as
the muscle became balancing. Patient should wear this at all
times initially if possible.
the splint increases the vertical dimension and position the
mandible in such the way that allow the jaw to move forward
as the muscle relaxed. The patient now can proceed to second
phase of the TMJ treatment.
Case treated by Dr. Bui at Cosmetic
Dentist of Katy
Dinh X. Bui, D.D.S., M.S.
is muscular disturbance?
Muscular disturbance plays a major role in Temporomandibular
(TMJ) joint dysfunction. In many cases of TMJ syndrome, inflammation
and muscle spasm occurs give rise to pain, inability to open
the mouth wide(trismus), and in sever cases, jaw lock. TMJ
joint dysfunction is a term to describe a collection of signs
and symptoms pertaining to the Temporomandibular joint degneration
and/or the disturbance of the muscle of mastications. Patient
most often referred to these symptom as clicking, crepitus,
tinitus, headache pains for a period of time, sore muscle
and jaw. Occasionally, these symptoms come and go, and may
be disappear after a while. This "silent stage"
may be a precursor to the more serious joint degeneration,
or just part of the adaptation which the joint-occlusion-muscle
complex adapt to operate at the satisfactory threshold, borderline
level. Nevertheless, patient will almost always benefit from
early intervention in order to avoid possible joint degeneration.
In many cases, symptom can be relieved or reduced greatly
For more information on TMJ, please
check out our article, TMJ-Pathology,
Diagnostic, Treatment and Splint Construction.
What are the muscles
involved with the TMJ joint-occlusion complex?
The muscle of mastication work
synchronously in pairs to help guiding masticatory movement
such as opening and closing of the mandible.
The major muscle pairs that involve
with opening (depressor muscles) are:
- Digastric: This is a sling muscle,
arises from the mastoid notch, attached to the tendon on
the hyoid bone, and sling forward to the digastric fossa
of the mandible. Its contraction pulls the mandible down
and back. This muscle will be exquisitely sensitive to palpation
if the mandible is chronically posteriorized
- Inferior head of lateral pterygoid
muscle: originates from the lateral surface of the lateral
pterygoid plate and inserts at the neck of the condyle.
Its contraction pulls the neck of condyle and cause the
mandible to glide forward (This occurs after the condyle
has rotated and mandible open about 21mm). This muscle will
exhibits soreness and pain to palpation upon chronic dysfunction
The major muscle pairs that involve
with the closure(elevator muscles) of the mandible are:
- Temporalis: Divided into the anterior portion which
elevates the mandible and the posterior portion which retracts
the mandible. Its middle portion both elevates and retracts.
This muscle can be palpated and show tenderness in TMJ patient
- Masseter: Originates from the medial surface of zygomatic
arch and inserts into the lateral surface of the ramus and
angle of the mandible. Its contraction produces a powerful
force to elevate the mandible. This muscle shows excessive
tonus in clenching or bruxing patient
- Medial Pterygoid: Originates from the medial surface
of the lateral pterygoid plate and inserts on the medial
surface of the angle of the ramus of mandible forming the
fascial sling with the masseter muscle
There are the suprahyoid muscles which plays minor role
(except for the digastric muscles which depress the mandible)
in guiding the movement of mandible and swallowing. They are:
Geniohyoid, Mylohyoid, Platysma, and the Digastric.
The superior head of the lateral pterygoid muscle arises
from the infratemporal surface of the greater wing of sphenoid
and inserts on the anteromedial portion of the TMJ disc. In
TMJ patient that exhibits clenching and bruxism, the superior
head of the lateral pterygoid muscle contracts at the end
of power stroking during closure of the mandible. Unilateral
contraction of the inferior head of the lateral pterygoid
contributes to the lateral movement of the mandible.
What happen to the muscle
surrounding the osteroarthitic TMJ?
The primary purpose for the muscle is to keep the parts
of the joint they straddle in contact. With the disc no
longer interposed between the condyle and eminence, these
bones articulates against each other and degenerate. The
degeneration brings about wearing down the articular surface
and shorten, which causes the muscles straddling the joint
to shorten its contracting length (the muscle pull distance
is shortened). When the muscle pull distance is shortened,
the strength increases and further rub the bones against
each other and further wear down its articulating surface.
This vicious cyle of shortening, break down, shortening,
How is the splint designed to help
balance the muscle involved in TMJ dysfunction patient?
The splint is designed to:
- position the mandible such that the muscle involved
can be function in harmony by eliminating all the interference
and stimulatory factor from the occlusion.
- artificially decompresses the tissue of the TMJ and
allow the disc to function between the articulating surfaces
of the condyle and the glenoid fossa.
- by discluding the teeth, the splint help to reduce
the proprioception into the central nervous system and thus
"deprogram" the mandible from its position. Now
the mandible is positioned by the balancing and harmonious
functioning of the muscles, not by the occlusion of the
- restores foreshortened masticatory muscles to their
resting length. As this occurs, the electrical activity
of muscles will decrease since the muscles are allowed to
rest more between function.
- restores the component parts of the TMJ to the normal
physiological position, allows for a normal range of function
concerning condyle-disc-eminence complex, and stabilizes
and limits TMJ functional movements to promote
healing to the tear or fibrosed ligaments.
What are the various splint designs
and their application?
Maxillary appliances are popularized by
crown and bridge restorative dentist due to the fact that
they usually restored the mandibular teeth first and therefore
want this arch to be unencumbered by the presence of the splint.
However, it binds up with the maxillary and palatine bones
and interfering with their movement. I always try to place
the splint on the mandibular arch for this very reason. It
is also unesthetic and therefore poor patient compliance.
The followings are the available splint designs:
- Smooth surfaces - myalgia patients
- Central occlusion
- Pull forward (SVED)
- Distalization of the mandible
- Thompson (pivot) - for closed lock
- Palatal expansion
- Sagittal - for incisal interference
- Entirely flat - myalgia patients
- Pull forward - for bilateral reciprocal clicks, unilateral
reciprocal clicks, and unilateral closed locks
- Pivot - for bilateral closed-lock TMJs
- Flexible nightguard
- Preformed nightguard
- Fillings on second molar or second premolar to increase
- Posture erector or correct forward head posture and
chronic cervical extension
If the problem is musculature in nature with no joint
derrangement (no clicking or popping or crepitus), a flat
mandibular splint is used. In the case of unilateral or bilateral
reciprocal clicks, a pull forward splint should be used, constructed
at the point anterior to that at which the click occurs. In
the case of bilaterally closed locked TMJ joints, pivotal
splint is used to move both condyles inferiorly simultaneously.
When the patient begin to click, the splint is converted to
a pull forward splint constructed slightly anterior to the
point of the click. Whenever patient exhibits a closed lock
unilaterally, the pull forward splint will be deliverred with
the use of the molt retractor with local anesthesia or manually
to allow decompression of the tissues or in some case the
disc will be able to pop into place. Finally, flat or pivotal
splint for the unilateral or bilateral reciprocal clicking
joint should be avoid because the mandible drops posteriorly
during sleep causing the clicking joint to become closed-locked.
How do we know that the splint
is working as expected?
Often we need to change our splint design as the joint
complex evolves into different stage during healing. Overally,
these are the positive signs of a "working" splint
- No joint noise
- Interincisal opening of 48 mm or more
- No deflection or deviation from opening
- Working excursion of 12 mm or more
- Condyle centered or anterior of center of fossa, radiologically
- Condyle travel past eminence and is separated from
it radiologically by 2mm (average thickness of the disc)
- New cortical bone formation if previously degenerated,
What else do we need to do after
the splint therapy has deemed successful?
The next phase of TMJ treatment usually involves orthodontic
therapy and crown and bridge. In extreme case, we may need
orthonagthic surgery and/or orthodontics and crown and bridge.
Rarely will the post treatment stabilization only require
equilibration. Equilibration usually will only effective in
short symptomatic period, young patient whom the joint complex
has not undergone osseous change and his or her dentition
does not develop compromising and pathological malocclusion.
What are the contraindication in
long term usage of the splint without moving forward to reconstructing
In many case, due to financial limitation, patient is
unable to move forward into the second phase of reconstructive
treatment. The splint will then act as part of the palliative
treatment (supportive treatment) and the symptom may relapse
due to many factors to be mentioned below. Long term usage
of the splint will:
- Posterior open bite: this phenomena happened when
the patient continously function with the splint and depressed
the mandibular posterior teeth. Anterior disclusion will
cause the anterior teeth to supraerupt and further worsen
the posterior open bite.
- Fremitus: the phenomena which the anterior teeth contact
prematurely during swallowing or functioning, results in
traumatic occlusion to the opposing maxillary anterior teeth
due to supraeruption of the mandibular anterior teeth. The
fremitus will cause localized vertical bone loss, inflammation
to the periodontium of the anterior teeth, and may result
in periodontal abscess.
- Clicking, popping, and headache may return due to
loss of vertical dimension (due to intruding mandibular
posteriror) and supraeruption of anterior introducing interference
I believe if the patient is unable to move to second
phase, the splint should be worn intermittently to provide
the teeth with antagonistic action and thus avoid these complications
to occur. The splint now is function palliatively to alleviate
the symptoms of TMJ dysfunction.
These are the protocol of which Dr. Bui, D.D.S., M.S.,
follows in his treatment modality. It is not necessary the
same or equivalent with other operator. Our method may be
different, but the final result should be toward eliminating
or relieving the TMJ dysfunction. I would like to extend my
gratitude to Dr. Brendan C. Stack, D.D.S, M.S. and Dr. John
E. Scott, D.D.S., M.S. for all my trainings and educations.
On the right hand column is an example of a
case using splint construction to treat TMJ. Patient presented
to the clinic complaining of pain radiated to the ear and
the periorbital region. She also experienced chronic headache,
tinnitus, sore in the jaw, and clicking and popping. The splint
was constructed to increase the vertical dimension and eliminate
the deep overbite and allow the mandible to move forward as
the muscles relax. Moreover, the jaw without teeth touching
is deprogrammed and allowed the muscle to position the mandible
at the most favorable physiologic position. Patient no longer
experiences these symptoms of TMJ disturbance. The next stage
is the treatment which includes orthodontic therapy (please
select TMJ/Orthodontic Therapy
under services menu)to eliminate overbite, erupting the mandibular
posteriors to increase vertical dimension, replacement of
broken or leakage restoration with crowns. For more information
about TMJ, please refer to our article, TMJ-Pathology,
Diagnostic, Treatment and Splint Construction.
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Dysfunction, Splint Construction"