C HAPTER 11 Occlusion and Temporomandibular Disorders Copyright © 2014, 2007, 2001, 1996 by Saunders, an imprint of Elsevier Inc.

CHAPTER 11

Occlusion and Temporomandibular Disorders Copyright © 2014, 2007, 2001, 1996 by Saunders, an imprint of Elsevier Inc.

INTRODUCTION

The masticatory system is a complex apparatus with an adaptive capacity to function. When that adaptive capacity is exceeded,

dysfunction can range from discomfort to debilitating pain.

Temporomandibular disorders (TMDs) occur as a result of problems with the masticatory system.

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Copyright © 2014, 2007, 2001, 1996 by Saunders, an imprint of Elsevier Inc.

BIOLOGICAL BASIS OF OCCLUSAL FUNCTION

The oral cavity in occlusal function (during talking, chewing, and swallowing) is in a dynamic (ever-changing) state rather than in a static state.

Orthofunction (physiologic occlusion) is a state in which the masticatory forces are within an adaptive physiologic range. In orthofunction, no pathologic changes occur in

the oral tissues.

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BIOLOGICAL BASIS OF OCCLUSAL FUNCTION (CONT.)

Dysfunction is a state of morphofunctional disharmony in which the forces during function cause pathologic changes in the tissues. These changes result in abnormal function or

pain. The degree of dysfunction can be slight, with no

great disturbance to the patient; or the degree of dysfunction can be significant, making daily activity difficult or impossible.

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In normal function, axial forces directed along the tooth and periodontium meet functional demands.

Parafunctional activity, such as grinding or clenching, can stress this system.

Antiaxial forces directed along the tooth and periodontium can cause resorption or a hypertrophic response. Some areas will break down, whereas other

areas will not show any injury.

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Certain factors affect the response of the teeth and periodontal structures to normal and abnormal function. These factors include the size and shape of the

roots, the quantity and quality of the alveolar bone, and the presence of microbial plaque biofilm.

Oral habits and/or missing or shifting teeth can also increase force on the teeth.

When periodontal disease has weakened the periodontium, these forces may exceed the individual’s adaptive capability, causing injury.

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When the condyles rest in a normal closed superoanterior position, the mandible has a well-distributed and even contact with the maxilla.

The masticatory system can tolerate a certain amount of functional change known as hyperfunction.

When functional changes exceed a certain level, alteration to the tissues may begin. This structural breakdown will vary, depending

on the individual and systemic and local factors.7


TRAUMA FROM OCCLUSION

A traumatic occlusion is an occlusion that has caused injury to the teeth, the muscles, or the temporomandibular joint (TMJ).

A classification of primary traumatic occlusion is made when heavy occlusal forces cause injury to tissues and bone.

A classification of secondary traumatic occlusion is made when normal occlusal forces exceed the capability of a periodontium that is already affected by periodontal disease.

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TRAUMA FROM OCCLUSION (CONT.)

Traumatic occlusion does not refer to a malocclusion as described by Angle’s three classifications. Angle’s Class I, II, and III occlusions classify and

describe the skeletal relationship of the maxillary to the mandibular teeth.

The occlusal relationship of the teeth is not a predictor of pain or problems in the TMJ.

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Trauma associated with orthodontic movement of teeth is self-limiting. Self-limiting means that mobility is greater than

normal but is handled through periodontal adaptation without causing trauma from occlusion.

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True trauma from occlusion, that is, trauma that exceeds the adaptive capacity of the periodontium, increases bone loss and pocket depth formation. Trauma from occlusion may occur with bruxism

in a patient with periodontal disease.

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Open or faulty contacts between teeth can cause areas of food impaction. Impaction is the forceful wedging of food into the

periodontium by occlusal forces. It can be a contributing factor in periodontal disease.

In the past, recession, clefting, or thickening of the gingival margin were thought to be caused by trauma from occlusion. Research has not supported these causative

relationships.

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TEMPOROMANDIBULAR DISORDERS

TMDs are a grouping of musculoskeletal conditions that produce pain or dysfunction in the masticatory system. When the muscles, not the joint, are involved,

the condition is referred to as extracapsular. A problem occurring within the TMJ is known as

intracapsular.

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CAUSES OF TEMPOROMANDIBULAR DISORDERS

The cause of TMDs is multifactorial. Stress is often a factor. Arthritis and psychologic problems can also be

involved. A history of macrotrauma or microtrauma may

exist. Macrotrauma is a single event. Microtrauma is a number of minor

habits or events.

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CATEGORIES OF TEMPOROMANDIBULAR DISORDERS

Four main diagnostic categories for TMD are listed:

1. Muscle and fascial disorders of the masticatory system

This group includes myalgia, trismus, spasm, dyskinesia, bruxism, and other muscle disorders.

2. Internal derangements that impair mechanical function of the TMJ

Arthritis conditions

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CATEGORIES OF TEMPOROMANDIBULAR DISORDERS (CONT.)

Four main diagnostic categories for TMD: (cont.)

3. Disorders of mandibular mobility This group includes ankylosis, muscular fibrosis,

internal derangement, and adhesions in the joint.

4. Disorders of maxillomandibular growth Neoplastic and nonneoplastic conditions Less common disorders

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ORAL HABITS

Oral habits can contribute to periodontal and dental damage in the oral cavity. The amount of damage is related to the intensity

and duration of the habit. Oral habits are repetitive masticatory

activities outside the normal range of function and can involve tooth-to-tooth contact or contact with foreign objects.

These habits can lead to tooth damage, muscular hypertrophy, muscular pain and tenderness, and periodontal tissue injury.

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BRUXISM

Bruxism is the most frequently described oral habit.

This oral habit is described as the clenching or grinding of the teeth when the individual is not chewing or swallowing.

Bruxism can occur as rhythmic side-to-side movements or through a sustained clench.

Clenching is the continuous or intermittent closure of the jaws under vertical pressure.

Grinding and clenching are parafunctional habits that are involuntary and may be destructive.

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BRUXISM (CONT.)

Bruxism is classified into one of two categories: Nocturnal (nighttime) Diurnal (daytime)

The results of bruxism may be tooth wear, tooth fracture, restoration fracture, myalgia, hypertrophy of the masticatory muscles, and headache. The presence of wear facets that are not caused

by masticatory function are indicative of tooth wear.

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BRUXISM (CONT.)

Bruxism treatments include: Occlusal splints Pharmacologic therapy Physical therapy Behavioral modification therapy

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BRUXISM (CONT.)

Bruxism can be a significant problem with patients who have advanced loss of periodontal support as demonstrated in the following figure.

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BRUXISM (CONT.)

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SIGNS AND SYMPTOMS OF TEMPOROMANDIBULAR DISORDERS

Four primary symptoms are commonly reported in patients with TMDs and include the following: 1. Pain and tenderness in the muscles of

mastication2. Pain and tenderness in the TMJ3. Painful clicking of the joint during function4. Limitation of mandibular motion

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SIGNS AND SYMPTOMS OF TEMPOROMANDIBULAR DISORDERS (CONT.)

A number of additional symptoms are found in patients with TMDs: Uncomfortable bite Incoordination of the jaw (dyskinesia) Ringing in the ears Muscle swelling

In the dentition, signs include tooth wear, tooth mobility, and pulpitis.

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Pain in the masticatory muscles (myalgia) is the most common symptom reported by patients with a muscle disorder.

Myalgia pain is usually dull, aching, and continuous or recurrent.

A reduction in mandibular function, usually the inability to open the mouth widely, is associated with muscle pain.

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Tenderness or pain in the TMJ (arthralgia) is another common finding in TMDs.

The pain arises from the soft tissues surrounding the joint because the articular surfaces of the joint are not innervated.

Arthralgic pain is sharp, sudden, and associated with the jaw in function.

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A common dysfunction observed in the TMJ is a joint sound caused by a disruption of the normal movement of the condyle and articular disk in the joint. A single sound is known as a click or a pop. A grating sound is known as crepitus.

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Other inflammatory joint disorders include osteoarthritis and polyarthritis. The pain of these disorders in the TMJ is dull,

aching, and constant, and is increased with function.

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SCREENING FOR TEMPOROMANDIBULAR DISORDERS

A TMD screening examination will lead to one of three conclusions:

1. The jaw system is in orthofunction; no contraindications to proceeding with dental hygiene treatment are revealed.

2. Problems exist in the jaw system; dental hygiene and dental treatment should proceed with caution, and the patient should be informed.

3. The patient should be referred for a comprehensive evaluation before any dental hygiene or dental treatment is administered.

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SCREENING FOR TEMPOROMANDIBULAR DISORDERS (CONT.)

The screening examination has subjective and objective components.

The subjective component is a series of questions that the patient is asked while the medical history is taken or during the examination of the oral cavity.

The clinician completes the objective portion; it is divided into the assessment of clinical jaw function and the assessment of occlusion.

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MUSCLE PALPATION

The temporalis and masseter muscles are bilaterally examined by palpating the origin, body, and insertion of the muscle.

Gentle finger pressure along the muscle, lasting a few seconds, is applied. This pressure may elicit a response from the

patient. The patient should be instructed to

differentiate pressure from pain.

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MUSCLE PALPATION (CONT.)

The muscle palpation examination is illustrated in the following figure.

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MUSCLE PALPATION (CONT.)

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MANDIBULAR MOVEMENT

The normal opening and closing of the jaw should be smooth and symmetrical. The patient should be able to achieve a

minimum of a 40 mm opening distance. If the clinician can passively increase the

interincisal distance for a patient, that is, use the thumb and finger to open the jaw wider, then a muscular problem may exist.

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MANDIBULAR MOVEMENT (CONT.)

The interincisal opening (incisal edge to incisal edge) is measured after the patient is asked to open the mouth as wide as possible as illustrated in the following figure.

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The normal mandibular movement from side to side and forward, with the teeth not in contact, should be approximately 8 mm.

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The left lateral, right lateral, and protrusive movements are demonstrated in the following figure.

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JOINT FUNCTION

Opening and closing should be observed for any alteration from the midline. A deviation is a shift in the midline during

opening that disappears later in the opening movement.

Interference in the disk of the joint may cause this deviation.

A deflection is a shift in the midline that becomes greater as opening continues.

A restriction in one joint causes a deflection.

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JOINT FUNCTION (CONT.)

The joint function movements are demonstrated in the following figure.

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JOINT FUNCTION (CONT.)

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JOINT SOUNDS

On opening, the condyle and disk of the TMJ move forward (anteriorly) to the articular eminence.

If a sound is elicited, then it is either a click or crepitus. A click is a short sound. Crepitus is a grating sound.

A sound that occurs on opening and closing is called a reciprocal click.

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JOINT SOUNDS (CONT.)

The examination of joint sounds is demonstrated in the following figure.

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JOINT SOUNDS (CONT.)

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INTERCUSPAL POSITION

The normal position of the teeth in maximum intercuspation is called centric occlusion. A normal position should be a well-distributed

pattern of occlusal contact. The posterior teeth should have firm, even

contact. The anterior teeth may have only light or no

contact.

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INTERCUSPAL POSITION (CONT.)

To evaluate anterior contact, polyester film (Mylar) or occlusal indicator (shim stock) paper is placed between the teeth at small intervals.

The patient is asked to close and hold on the Mylar while the operator tugs slightly outward. If the Mylar strip holds, then contact exists. If the Mylar strip slips through the teeth, then no

contact exists.

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INTERCUSPAL POSITION (CONT.)

The presence or absence of intercuspation contact should be noted for the incisors, canines, premolars, and molars on the right and left sides of the mouth as demonstrated in the following figure.

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PROTRUSIVE, LATERAL, AND MEDIAL EXCURSIVE MOVEMENTS

Lateral movement of the jaw is examined starting from the intercuspal position.

The patient protrudes the jaw as far as possible and moves the jaw toward the right shoulder and then toward the left shoulder.

A supracontact (high spot) is an area on a tooth that prevents well-distributed stable contact between the maxillary and the mandibular teeth.

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PROTRUSIVE, LATERAL, AND MEDIAL EXCURSIVE MOVEMENTS (CONT.)

Medial movement is also examined starting from the intercuspal position.

Mylar film is placed between the molars on the right side and the patient moves the jaw 2 mm toward the opposite side. If the Mylar does not hold, then no contact

exists. If it holds, then a mediotrusive contact exists.

This test is repeated on the left side.

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The test for medial movement is illustrated in the following figure.

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TOOTH MOBILITY AND WEAR

Slight mobility of the teeth, especially the lower incisors, is normal.

This ability to move is called physiologic mobility and occurs because the conical roots of single-rooted teeth are suspended in the periodontal ligament, which allows them to move very slightly.

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TOOTH MOBILITY AND WEAR (CONT.)

A classification of primary traumatic occlusion is made when heavy occlusal forces exceed the adaptive range in a normal periodontium.

A classification of secondary traumatic occlusion is made when normal occlusal forces exceed the capability of a periodontium that is affected by periodontal disease.

The visible and palpable movement of a tooth during function or parafunction is called fremitus. 54



To feel the movement, the dental hygienist places a finger over the tooth root on the attached gingiva as demonstrated in the following figure.

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Wear caused by tooth-to-tooth contact is called attrition.

A facet is a type of attrition where the tooth surface is worn by functional or parafunctional causes. A facet is smooth and shiny as a result of the

enamel rods that become fractured and polished. Shiny facets are known as active facets.Nonshiny or velvetlike facets are termed passive facets.

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When the facet is angular, the occlusal forces are directed laterally and increase the risk of periodontal injury.

To determine whether the wear is from functional or parafunctional use, the dental hygienist asks the patient to close his or her mouth and then observes the position of the mandible.

If an occlusal pattern for the wear cannot be established, then other factors must be considered.

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Oral habits, such as nail biting or foreign substance abrasion, can also cause tooth wear as demonstrated in the following figure.

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RADIOGRAPHIC EVALUATION

Changes observed in periapical radiographic images include: Widening of the periodontal ligament

This is caused by the resorption of bony support from excessive occlusal forces.

Increased density of the surrounding bone (osteosclerosis)

Increased cementum at the apical areas of the root (hypercementosis) Osteosclerosis and hypercementosis are hypertrophic responses to occlusal forces. 59


RADIOGRAPHIC EVALUATION (CONT.)

Examples of these changes in conditions are demonstrated in the following figure.

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A temporomandibular screening form is demonstrated in the following figure.

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TREATMENT OF TEMPOROMANDIBULAR DISORDERS

Three criteria are used as guidelines for selecting a TMD treatment:

1. Corrects the differential diagnosis2. Is selected with reason and purpose3. Is directed toward eliminating or neutralizing the

cause of the symptoms

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TREATMENT OF TEMPOROMANDIBULAR DISORDERS (CONT.)

A commonly used approach is conservative, using simple, noninvasive methods.

Initial therapy consists of a soft diet, limited movement of the jaw, application of moist heat to the affected area, and a nonnarcotic analgesic. Stronger drugs may be prescribed if symptoms

do not respond to the nonnarcotic analgesic agents.

Patients frequently improve after 2 to 3 weeks of initial therapy. 64



Home Therapy Home therapy includes a soft diet, heat or ice

packs, nonnarcotic analgesics, rest, and some jaw movement exercises. The jaw movement exercises are demonstrated

to the patient, and a daily program is recommended.

The exercises both relax and stretch the sore muscles to enable them to regain their original function.

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Physical Therapy Physical therapy treatments include:

Ultrasound Massage Electrical stimulation of the muscles Soft-tissue manipulation Exercise programs

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Occlusal Appliances Occlusal appliances are made of hard acrylic

resin. They fit over the occlusal and incisal surfaces

of the maxillary or mandibular teeth. The appliance may be called a splint, night

guard, or bite guard. An occlusal appliance protects the teeth and

provides a stable position for them.

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Occlusal Adjustment Limited occlusal adjustment may be

appropriate in some patients, but it is rarely considered a primary treatment for TMDs.

Behavioral Therapy Behavioral methods include:

Stress or anxiety counseling Depression counseling Psychiatric therapy

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Pharmacologic Therapy Groups of medications prescribed include:

Analgesic medications Antianxiety drugs Antiinflammatory agents Muscle relaxants Local anesthetic medications

Administered orally or by injection

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Surgical Therapy Arthroscopic and arthrocentesis surgeries

can help patients with acute TMJ derangement–induced hypermobility to gain a full range of jaw motion.

A condylectomy (removal of the condyle), which is more extensive than a condylotomy (partial removal), may be indicated for severe TMJ growth disturbances or tumors.

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Irreversible Treatments Irreversible treatments for TMD, such as

surgery to the joint or disk, are permanent alterations. Surgical treatments are indicated only in a small

percentage of patients. Occlusal adjustment is irreversible, and no

evidence suggests that this approach is effective.

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DENTAL HYGIENE APPOINTMENT

The patient with TMD requires a series of short dental hygiene appointments, rather than one long appointment, to minimize trauma to the masticatory muscles and joint.

The use of a bite-block to maintain the oral opening is one alternative for a patient with a history of jaw pain and fatigue.

The use of a toothbrush with a small head or the use of other interdental cleaning devices can simplify daily oral hygiene care for patients with limited opening.

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C HAPTER 11 Occlusion and Temporomandibular Disorders Copyright © 2014, 2007, 2001, 1996 by Saunders, an imprint of Elsevier Inc.

Documents

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masticatory forces

abnormal function

masticatory system

o cclusion

occlusal function

functional changes

c hapter