OCCLUSAL SPLINTS IN TMJ DISORDERS

INTRODUCTION: An occlusal appliance which is often called as a splint, is a removable device, usually made of hard acrylic that fits over the occlusal and incisal surfaces of teeth in one arch, creating precise occlusal contact with the teeth of opposing arch. It is commonly referred to as bite guards, night guard, inter occlusal appliances, intra-oral arthotic, or even orthopedic device. These are extensively used in management of TMJ disorders. They had shown considerable control in myofacial pain, however no clear hypothesis about the mechanism of action has been proved. It has more of diagnostic value, for example, if a patient responds favorable to an occlusal device then the response to the same restorative permanent treatment should be positive. So it serves as an important diagnostic value before going to a fixed prosthodontic therapy.

DEFINITIONS Temporomandibular joint:

The articulation between the temporal bone and the mandible. It is a diarthroidal, bilateral ginglymus arthroidal joint.

The articulation of the condylar process of the mandible and the interarticular disk with the mandibular fossa of the squmous portion of temporal bone; movement in upper joint compartment is mostly translational, whereas in the lower joint compartment is mostly rotational.

The joint connects the mandibular condyle to the articular fossa of the temporal bone with the temporomandibular disc interposed.

Temporomandibular Disorders:“Abnormal, incomplete, or impaired function of TMJ”.

Occlusal Splint/ Occlusal Device/ Orthotics:“Any removable artificial occlusal surface used for diagnosis or

therapy affecting the relationship of the mandible to the maxillae. It may be used for occlusal stabilization, for treatment of TMJ disorders, or to prevent wear of the dentition.”

Occlusal Pivot:“An elevation placed on the occlusal surface, usually in the molar

region, designed to act as a fulcrum, thus limiting mandibular closure and inducing mandibular rotation”.

Occlusal Prematurity:“Any contact of opposing teeth that occurs before the planned

articulation”.

Bruxism/ Tooth Grinding/ Occlusal Neurosis:“The parafunctional grinding of teeth”.“An oral habit consisting of involuntary rhythmic or spasmodic

non-functional gnashing, grinding or clenching of teeth, in other than chewing movements of mandible, which may lead to occlusal trauma”.

PURPOSE:The purpose of occlusal treatment is to make the teeth conform to a

correct skeleton-related position of the condylar axis. The purpose of occlusal splints is to provide an indirect method for

altering the occlusion until the correctness of the condylar axis position can be determined and confirmed.

ADVANTAGES OF OCCLUSION SPLINT:1. Stabilization of weak teeth: An occlusal splint can effectively

stabilize weak or hypermobile teeth by the adaptation of the splint material around the axial surfaces.

2. Distribution of occlusal forces3. Reduction of wear 4. Stabilization of unopposed teeth

Occlusal splints cannot cause effects that are in violation of mechanical laws. Thus an occlusal splint does not unload the condyles. The popular claim that a posterior occlusal splint serves as a pivot for distraction of the condyles is in violation of facts of anatomy, laws of physics, and clinical data.

VARIOUS UNEXPLAINED THERAPEUTIC CLAIMS1. Occlusal splints increase the wearer’s strength 2. Occlusal splints cause remission of unrelated diseases3. Occlusal splints can cause a ‘purging of system poisons’4. Occlusal splints cause a ‘regulation of multiple bodily functions’.

TYPES OF OCCLUSION SPLINT:According to Okeson

1) Muscle relaxation appliance/ stabilization appliance used to reduce muscle activity

2) Anterior repositioning appliances/ orthopedic repositioning appliance

Other types:

a) Anterior bite planeb) Pivoting appliance c) Soft/ resilient appliance

According to Dawson:1. Permissive splints/ muscle deprogrammer2. Directive splints/ non-permissive splints 3. Pseudo permissive splints (e.g Soft splints, Hydrostatic splint)

MORA – mandibular orthopedic repositioning appliance

Types of Occlusal Splints:1. Permissive splint or 2. Directive splint

Permissive Splints: Are designed to unlock the occlusion to remove deviating tooth inclines from contact. The condyles are then allowed to return to their correct seated position in centric relation if the condition of the articular components permits.

Permissive splints are often referred to as muscle deprogrammers. A properly made centric relation occlusal splint is a permissive splint.

If a centric relation splint is made with deep fossae and inclines that are too steep, it can be turned into a directive splint that limit condylar access to centric relation only.

Directive splints: Are designed to position the mandible in a specific relationship to the maxilla. The sole purpose of a directive splint is to position or align the condyle-disk assemblies. Thus directive splints should be used only when a specifically directed position of the condyles is required.

Contraindications for Directive Splints:1. The condyle and the disk can be aligned correctly. 2. The correctly aligned condyle-disk assemblies can move to the

most superior position against the eminentiae without derangement.

3. The disks can maintain their alignment with the condyles during function.

Verification that the condyle-disk assemblies are capable of normal function in the most superior position can be achieved on a tentative basis by testing in the following manner:

1. Load testing the joints with bilateral pressure2. Clench testing with the teeth separated3. Doppler auscultation

Superior Repositioning Splints:The purpose of anterior repositioning therapy is fulfilled when the

retrodiskal tissues have healed sufficiently to regain a backward pull on the disk. However, either the condyle or the disk may have difficulty moving back to centric relation after being held forward. There is reason to suspect that the inferior lateral pterygoid muscle is shortened by long-term use of anterior repositioning devices. This makes it more difficult for the muscles to release the condyles to their most superior position. Deformity of the displaced disk may also require time to adaptively remodel to a stable contour.

The purpose of a superior repositioning splint is to eliminate the effect of the neuromuscular reflex that directs the mandible to close repetitively into the maximum intercuspation position. By covering the occlusal surfaces with plastic to provide a smooth surface, you can eliminate the reflex and the mandible can have free access to the seated position.

The goal is a true skeletal relationship of the mandible to the maxilla and not one that is influenced by the maximum intercuspation of the teeth. The purpose of the superior repositioning splint is to establish the correct skeletal relationship before the correct occlusal relationship is determined.

The fabrication of a superior repositioning splint is identical to the centric relation splint. It is especially important that the anterior guidance on the splint must disclude all posterior teeth in all jaw positions except centric relation.

The time required to achieve superior positioning of the condyle-disk assembly varies from patient to patient. It may occur in a few days, or it may take several months. The determining factors appear to be related to the amount of deformity of the recaptured disk, and the condition of the inferior and superior bellies of the lateral pterygoid muscles.

Prolonged anterior disk displacement often results in shortening of the superior lateral pterygoid muscle, which controls the alignment of the disk.

Even when the disk will not be released all the way to centric relation, the superior repositioning splint may be beneficial. It offers an alternative when the disk cannot stay aligned and the patient elects against reparative surgery.

GENERAL CONSIDERATIONS:Appliance therapy has several favorable qualities that render it

extremely helpful for the treatment of many TM disorders. An appliance can affect a patient’s symptoms in several ways. It is extremely important that when it reduces symptoms the precise cause-and-effect relationship be identified before irreversible therapy is begun.

Occlusal appliances are equally helpful in ruling out certain etiologic factors. When a malocclusion is suspected of contributing to a TM disorder, occlusal appliance therapy can quickly and reversibly introduce a more desirable occlusal condition.

They are a reversible non-invasive modality that can help manage the symptoms of many TM disorders. The success or failure of occlusal appliance therapy depends on the selection, fabrication, and adjustment of the appliance and on patient cooperation.

MUSCLE RELAXATION APPLIANCE / Flat Plane, Share (maxillary), Tanner (mandibular), Superior repositioning Muscle Deprogramming, or CR Splint:

Description and Treatment Goals:The muscle relaxation appliance is generally fabricated for the

maxillary arch. When it is in place, the condyles are in their most musculoskeletally stable position at the time that the teeth are contacting evenly and simultaneously. Canine disocclusion of the posterior teeth during eccentric movement is also provided. Treatment goal eliminate any orthopedic instability between the occlusal position and the joint position.

Indications:1) Treat muscle hyperactivity 2) Decrease the parafunctional activity 3) Bruxism4) Local muscle soreness or myositis 5) Retrodiscitis secondary to trauma.

Simplified fabrication technique:An alginate impression is made of the maxillary arch. It is poured

immediately with a suitable gypsum product. With a pressure or vacuum adapter, 2-mm-thick hard, clear resin sheet of material is adapted to the cast.

The outline of the appliance is then cut off the cast with a separating disk. The cut is made at the level of the interdental papilla on the buccal and labial surfaces of the teeth.

The lingual border of the appliance extends 10 to 12 mm from the gingival border of the teeth throughout the lingual portion of the arch. The labial border of the appliance terminates between the incisal and middle thirds of the anterior teeth.

A small amount of clear self-curing acrylic resin is mixed in a dampen dish. It is added to the occlusal surface of the anterior portion of the appliance. This acrylic will act as the anterior stop. It is approximately 4 mm wide and should extend to the region where a mandibular anterior central incisor will contact.

Locating the musculoskeletally stable position: Bilateral manual manipulation technique.

In the other technique, a stop is placed on the anterior region of the appliance and the muscles are used to locate the musculoskeletally stable position of the condyles. (This technique uses the same principles employed with the leafgauge).

The contact on the anterior stop is marked with articulating paper and adjusted so it provides a stop that is perpendicular to the long axis of the mandibular tooth being contacted.

If a distal inclination exists on the stop, clenching will force the mandible posteriorly away from the musculoskeletally stable position. The anterior stop should not be mesially inclined and create a forward shift or slide of the mandible, because the clenching will tend to reposition the condyle forward, away from the most musculoskeletally stable position.

Developing the Occlusion:When the CR position has been located, the patient should become

familiar with it by wearing the appliance for a few minutes. Instructions are given to tap on the anterior stop.

The appliance is removed from the mouth and self-curing acrylic is added to the remaining anterior and posterior regions of the occlusal surface.

The appliance is then returned to the mouth, and the patient either closes or is guided into CR. The mandibular teeth should sink into the soft acrylic until the incisors contact the anterior stop.

Adjusting the CR Contacts:The occlusal surface of the appliance is best adjusted by first

marking the deepest area of each mandibular buccal cusp tip and incisal edge with a pencil.

The acrylic surrounding the pencil marks is removed so the relatively flat occlusal surface will allow eccentric freedom.

All contacts, both anterior and posterior, should be carefully refined so they will occur on flat surfaces with equal occlusal force.

Adjusting the eccentric guidance:The acrylic prominences labial to the mandibular canines are

smoothed. They should exhibit about a 30- to 45-degree angulation to the occlusal plane and allow the canines to pass over in a smooth and continuous manner during protrusive and laterotrusive excursions.

It is important that the mandibular canines move freely and smoothly over the occlusal surface of the appliance. If the angulation of the prominences is too steep, the canines will restrict mandibular movement and may aggravate an existing muscle disorder.

Eccentric contacts of the mandibular central and lateral incisors also must be eliminated so the predominant marks are those of the mandibular canines.

During a protrusive movement, guidance by the maxillary canines, not the mandibular central and lateral incisors, is the goal.

Final criteria for the muscle relaxation appliance:The following eight criteria must be achieved before the patient is

given the muscle relaxation appliance: 1. It must accurately fit the maxillary teeth, with total stability and

retention when contacting the mandibular teeth and when checked by digital palpation.

2. In CR all posterior mandibular buccal cusps must contact on flat surfaces with even force.

3. During protrusive movement the mandibular canines must contact the appliance with even force. The mandibular incisors may also contact it but not with more force than the canines.

4. In any lateral movement only the mandibular canine should exhibit laterotrusive contact on the appliance.

5. The mandibular posterior teeth must contact the appliance only in the CR closure.

6. In the alert feeding position the posterior teeth must contact the appliance more prominently than the anterior teeth.

7. The occlusal surface of the appliance should be as flat as possible with no imprints for mandibular cusps.

8. The occlusal appliance is polished so it will to irritate any adjacent soft tissues.

Instructions and adjustments:The patient is instructed in proper insertion and removal of the

appliance.

Finger pressure is used to align and seat it initially. Removal is most easily accomplished by catching it near the first molar area with the fingernails of the index fingers and pulling the distal ends downward.

When bruxism is the problem nighttime use is essential while day use may not be as important. When the disorder is retrodiscitis, the appliance may need to be worn most of the time. It has been demonstrated that myogenous pain disorders respond best to part-time use (especially nighttime use) while intracapsular disorders are better managed with continuous use. If wearing causes increased pain, the patient should discontinue wearing and report the problem immediately for evaluation and correction.

On certain occasions fabrication of a mandibular muscle relaxation appliance may be desirable. Evidence suggests that maxillary and mandibular appliances reduce symptoms equally. The primary advantages of the mandibular type are that it affects speech less and aesthetics may be better.

ANTERIOR REPOSITIONING APPLIANCE:Description and Treatment Goals:

The anterior repositioning appliance is an interocclusal device that encourages the mandible to assume a position more anterior than the intercuspal position. Its goal is to provide a better condyle-disc relationship in the fossae so normal function will be reestablished. The goal of treatment is not to alter the mandibular position permanently but only to change the position temporarily so as to enhance adaptation of the retrodiscal tissues.

Indications:To treat disc derangement disorders. Patients with joint sounds

(e.g., a single or reciprocal click) can sometimes be helped by it. Intermittent or chronic locking of the joint (e.g., retrodiscitis).

Simplified fabrication technique:Like the muscle relaxation appliance, the anterior repositioning

appliance is a full-arch hard acrylic device that can be used in either arch. However, the maxillary arch is preferred because a guiding ramp can be more easily fabricated to direct the mandible into the desired forward position.

Fabricating and fitting the appliance:The initial step in fabricating a maxillary anterior repositioning

appliance is identical to that in fabricating a muscle relaxation appliance. The anterior stop is constructed and the appliance is fitted to the

maxillary teeth. Acrylic extending over the labial surfaces of the maxillary teeth is not needed for occlusal purposes.

Locating the correct anterior position:The key to successful anterior repositioning appliance fabrication

is finding the most suitable position for eliminating the patient’s symptoms. The anterior stop is used to locate it.

The patient is instructed to protrude slightly and to open and close in this position. The joint is reevaluated for symptoms and the anterior position that spots the clicking is located and marked with red marking paper as the patient taps on the stop.

Once this has been marked, the appliance is removed and the area of the contact is grooved approximately 1 mm deep with a small round bur. The appliance is then returned to the mouth and the patient locates the groove and taps into it.

There should be no joint sounds during opening and closing. Joint pain during clenching should also be reduced or eliminated. Myogenous pain originating from the superior lateral pterygoid, however, will not be eliminated since this muscle is active during clenching.

When the joint symptoms have been eliminated and verified by the anterior stop, the appliance is taken out of the patient’s mouth and self-curing acrylic is added to the remaining occlusal surface so all occlusal contacts can be established.

The anterior stop must not be covered by the acrylic. When the anterior teeth are felt to contact in the groove on the

anterior stop, the position is verified by opening and closing a few times. With the teeth resting together, the patient should gently place his tongue on the setting resin lingual to the anterior teeth and press. This will adapt the resin to the lingual surfaces of the mandibular anteriors and provide the needed ramp for guiding the mandible into the forward position.

Adjusting the occlusion:The difference with this appliance is the anterior guiding ramp,

which requires the mandible to assume a more forward position to ICP.Flat occlusal contacts are developed for the posterior teeth, and the

large lingual ramp in the anterior region is only smoothed. The ramp is developed into a smooth sliding surface so as not to promote catching or locking of the teeth in any position.

Final criteria for the anterior repositioning appliance: The following four criteria should be met by the anterior

repositioning appliance before it is given to the patient:

1. It should accurately fit the maxillary teeth, with total stability and retention when in contact with the mandibular teeth and when checked by digital palpation. In the established forward position all the mandibular teeth should contact it with even force.

2. The forward position established by the appliance should eliminate the joint symptoms during opening and closing to and from that position.

3. In the retruded range of movement the lingual retrusive guidance ramp should contact and upon closure direct the mandible into the established forward position.

4. The appliance should be smoothly polished and compatible with adjacent soft tissue structures.

Instruction and Adjustments:Instructions regarding insertion and removal of the anterior

repositioning appliance are given. Instructed to wear the appliance at night and during the day as needed to reduce symptoms. On occasion a patient may need to wear this appliance all the time depending on the severity of the symptoms.

ANTERIOR BITE PLANE/ ANTERIOR JIG LUCIA JIG, HAWLEY WITH BITE PLANE/ ANTERIOR DEPROGRAMMES:

Description and Treatment Goals:The anterior bite plane is a hard acrylic appliance worn over the

maxillary teeth providing contact with only the mandibular anterior teeth. It is primarily intended to disengage the posterior teeth and thus eliminate their influence on the function of the masticatory system.

Indications:Muscle disorders related to orthopedic instability or an acute

change in the occlusal condition.

Disadvantages:If the appliance is worn continuously for several weeks or months,

there is a great likelihood that the unopposed mandibular posterior teeth will supraerupt. When this occurs and the appliance is removed, the anterior teeth will no longer contact and the result will be an anterior open-bite.

Anterior bite plane therapy must be closely monitored and used only for short periods.

POSTERIOR BITE PLANE:

Description and treatment goals:The posterior bite plane is usually fabricated for the mandibular

teeth and consists of areas of hard acrylic located over the posterior teeth and connected by a cast metal lingual bar. The treatment goals of the posterior bite plane are to achieve major alterations in vertical dimension and mandibular repositioning.

Indications:Severe loss of vertical dimension or when there is a need to make

major changes in anterior repositioning of the mandible. Some therapists have suggested that this appliance be used by athletes to improve athletic performance. However, scientific evidence does not support this theory.

Disadvantages:Potential supraerutpion of the unopposed teeth and/or intrusion of

the occluded teeth. Constant and long-term use should be discouraged.

PIVOTING APPLIANCEThe pivoting appliance is a hard acrylic device that covers one arch

and usually provides a single posterior contact in each quadrant. This contact is usually established as far posteriorly as possible. When superior force is applied under the chin, the tendency is to push the anterior teeth close together and pivot the condyles downward around the posterior pivoting point.

Indications:The pivoting appliance was originally developed with the idea that

it would lessen interarticular pressure and thus unload the articular surfaces of the joint.

Unfortunately, the forces of the elevator muscles are located primarily posterior to the pivot, which therefore disallows any pivoting action.

In fact, the pivoting appliance has been advocated for the treatment of symptoms related to osteoarthritis of the TMJs. For the treatment of an acute unilateral disc dislocation without reduction.

SOFT OR RESILIENT APPLIANCE

Description and Treatment Goals:

The soft appliance is a device fabricated from resilient material that is usually adapted to the maxillary teeth. Treatment goals are to achieve even and simultaneous contact with the opposing teeth.

Indications:1) Protective device for persons likely to receive trauma to their

dental arches 2) Protective athletic splints decrease the likelihood of damage to the

oral structures when trauma is received. 3) Clenching and bruxism

Okeson demonstrated that nocturnal masseter EMG activity was increased in 5 to 10 subjects with a soft appliance; in the same study 8 of the 10 subjects had significant reduction of nocturnal EMG activity with a hard muscle relaxation appliance.

Common Treatment Considerations of Appliance Therapy:However, much controversy exists over the exact mechanism by

which occlusal appliances reduce symptoms. Most conclusions are that they decrease muscle activity (particularly parafunctional activity).

Before any permanent therapy is begun, one needs to be aware that there are six general features common to all devices that may be responsible for decreasing muscle activity and symptoms.

1. Alteration of the occlusal condition 2. Alteration of the condylar position 3. Increase in the vertical dimension 4. Cognitive awareness 5. Placebo effect: 40% of the patients suffering from certain TM

disorders respond favorably to such treatment. 6. Increased peripheral input to the CNS: Any change at the

peripheral input level seems to have an inhibitory effect on this CNS activity.

SUMMARY AND CONCLUSIONDespite the unanswered questions on the physiologic mechanisms

that explain the effectiveness of intra-oral appliances on reducing symptoms of TMD, there is still a plethora of documentation that intra-oral appliance when used in the management plan accurately, can contribute to the relief of TMD symptoms. The clinician is encouraged to evaluate fully each particular patient case in an effort to develop a differential diagnosis that leads to effective management plan.

Before commencing any appliance therapy for a TMD, the clinician should be confident that the patient will benefit from the

therapeutic approach. If the symptoms reduced that will provide additional diagnostic information.

The clinician also needs to consider that 40% of patients suffering from TMD demonstrate favorable response to therapy from a placebo effect. As with any treatment, a good patient-dentist relationship and concomitant with patent education, can alloy patient feelings and anxieties.

It can contribute to a positive and favorable response to intra-oral occlusal splint therapy.

REFERENCES:1. Shillingburg: Fundamentals of Fixed Prosthodontics, ed 3, Chicago,

Quintessence Publication Co 1997.

2. Stephen Rosenstiel, Martin Land: Contemporary Fixed Prosthodontics. USA, Mosby Co 1998, ed 2.