bruxism, an overview and management

BRUXISM, AN OVERVIEW AND MANAGEMENT.

BY: DR. BAHJAT ABU HAMDAN

CONSULTANT PROSTHODONTIST

DDS, CES, DSO

Bruxism.

1. Introduction.

2. Definition.

3. Epidemiology.

4. Etiology.

5. Characteristics.

6. Clinical consequences.

7. Diagnosis.

8. Management.

1. Introduction.

Before understanding the pathology of any disorder in the human body, one should have a good knowledge of the following elements:

The anatomy. The related physiology. The interrelation with the other elements. The biochemistry mechanism.

2. Definition. Bruxism can be regarded as forcible clenching or

grinding of the dentition, or a combination of both. Clenching of the teeth is a forcible closure of the

opposing dentition in a static relationship of the mandible to the maxilla. In either maximum intercuspation or an eccentric positions.

Grinding of the dentition is a forcible closure of the opposing dentition in a dynamic maxillo-mandibular relationship as the mandible moves through various excursive positions.

Definition. AAOFP defined bruxism as “diurnal or nocturnal

parafunctional activity including clenching, bracing, gnashing and grinding of the teeth.

Bruxism, diurnal or nocturnal, is considered as a potential contributing factor to disturbances of the masticatory system.

Many individuals are not cognizant of their parafunctional behaviors, because these activities are usually subconscious, so obtaining accurate response regarding his mandibular parafunctional activity can be challenging.

Definition.

Bruxism, as disorder of the neuromuscular activity, may affect any element of the masticatory system:

Regional or local pain, it may include one or more of the muscles of mastication. The myalgia may worsen during function. Limitation of mouth opening could be noticed as well as tenderness on palpation.

Wearing of the teeth, and TMJ problems. In certain cases symptoms may involve all the precedent elements.

3. Epidemiology.

Some studies demonstrate that bruxism occur in up to 90% in the general population.

Other studies demonstrate that it affects 8% of the adult, 14% of the children, and 10-12% of the adolescents.

However some investigations showed that the incidence is highest in the teens and the forties, and that behavior decreases with age.

Studies indicate that females report parafunctional clenching more than males.

Epidemiology.

However clinical observations demonstrate approximately an equal distribution.

Self reporting of clenching during waking hours is about 20%.

Grinding of the teeth during sleeping hours ranges from 6-12%.

Parafunctional behavior is performed at a subconscious level by most individuals so determination the actual prevalence is difficult.

4. Etiology.

The cause of bruxism still controversial. The cause is multi factorial and

overlapping, which creates difficulties in applying comprehensive, effective management plan for this mandibular parafunctional behavior.

However, because the parafunctional mandibular movements concern mainly the neuromuscular system, so any situation stimulating this system, at the subconscious level, would contribute in starting up bruxism.

Etiology. Historically, occlusal interference were thought to be

the precipitating factor for bruxism, the assumption was that the patient was working a subconscious attempt at performing a self-equilibration or an adjustment of his dentition to remove the occlusal interferences, particularly with nocturnal bruxism.

Recent studies have refuted this assumption, but other investigators have reported that patient response to an occlusal interference, which existed, is more significant than to an actual presence of interference

Etiology. However, the relationship of the dentition may be a

contributing factor. Bruxism is considered as the most destructive

functional disorder to the dentition. Emotional or physical stress as well as anticipating of

stress, are related to the mandibular parafunctional behavior.

Bruxist activity has been associated with sleep disorder.

It is reported that bruxism has been aggravated by alcohol consumption and certain medication.

Etiology. Occlusal interferences act as trigger factors for

nonfunctional movements. Both centric and eccentric bruxism are expressions

of increased muscle tonus. Its often said that bruxism in centric excursion

involves isotonic muscle contractions, while static clenching in CO represent isometric activity.

But even the minute jaw movements include changes in the muscle length, so that, clenching involves both isotonic and isometric activity.

Normal function in lateral movement.

Excursive bilateral joint strain interferences.

Non working interference strain.

Canine working intensity

Canine rise becomes canine clenching

Etiology.

Any type of occlusal interference may, when combined with psychic stress, initiate and maintain bruxism.

Discrepancy between CR and CO is the most common trigger factor for bruxism.

Interference in the balancing side is the second is the second significant occlusal trigger factor.

Interference in the working side or protrusive excursion may also trigger bruxism.

CR to CO movement.

Protrusive clenching.

Etiology. Since bruxism is an expression of combined psychic and

occlusal factors. Bruxism may be present on the basis of severe occlusal interference and moderate degree of psychic or emotional tension, also it can be the result of very severe psychic stress and very little occlusal interference.

A force as little as1.5 gm or less is detectable by the teeth. ( Munch and schriever ).

Bodies of 8-20 micron could be detected by some individuals, and 60 mic were detected by all. (Kraft, Tryde, Siirila and Lane)

Etiology.

A state of hyper tonicity muscles might therefore be due to either :

CNS influence through the fusimotor system.

LOCAL disharmony between the functional parts of the masticatory system activity.

The emotional influences on the muscles of mastication is well known to clinicians.

Apprehension of dental procedures increase muscle tone, and positioning of the jaw accurately becomes difficult if not impossible.

Schematic representation of the relationship of local and environmental factors to dysfunctional disturbances of the masticatory system.

Etiology.

Occlusal habits are all outlets for emotional and psychic tension and have no relation with occlusal disharmony as in the case of bruxism.

The only indirect effect of occlusal interferences is possibly an increase of muscle tonicity.

The precipitating factors of these habits ( lip, tong, cheek and fingernail biting) may be overwork, worry, and premenstural or other tensions having frustrations as the common background.

5. Characteristics.

Studies are focused on the nature of nocturnal bruxism because of practical limitations of investigating diurnal bruxist behavior.

Mandibular para functional behavior during the sleeping hours:

RHYTHMIC, and forceful GRINDING. PROLONGED CLENCHING; sustained

clenching can occur either in maximum intercuspation, and /or eccentric intercuspation anterior or lateral position.

Characteristics. Masticatory system is more prone to deleterious

ramification from forces generated by bruxism than forces generated by functional tooth contact.

Duration, Frequency, and Intensity of the mandibular parafunctional activity is of paramount significance in contributing to the resulting effect. Bruxist forces affect the structures of the masticatory system:

Dentition and their supporting tissues. The associated musculature. The TMJ

Characteristics.

The mandibular rhythmic movements of nocturnal bruxism reflect episodic patterns that can occur at intermittent intervals.

25 bruxist episode per night each episode may have duration of 8-9 sec.

Other study reported episode of 5 minutes.

Total average bruxing time per period 42 sec. Other study reported 162 mint. With different behavior from night to night.

Characteristics.

Functional tooth contact during 24 hours is approximately 20 minutes.

The excessive forces generated by bruxism extends for more than 20 minutes.

Nocturnal bruxism can generate greater occlusal forces (subconscious) than conscious effort during working hours.

One study demonstrated that 65% of nocturnal bruxing episodes exceeded forces generated by mastication.

Characteristics.

The average working force that can be delivered to a natural tooth is about 175 PSI (80 KG), 50 KG for FPD, and 10 Kg for CD, wherever nocturnal bruxist can increase this force 300 PSI with reported cases of 100,000 to 175,000 PSI (intensity).

Functional activity can generate tooth contact forces about 17,200 lb/sec/day.

Para functional activity generate about 57,000 lb/sec/day.

Characteristics. It is possible that cortical inhibitions normally

operational during the working hours are suppressed during sleeping hours, thereby allowing the masticatory muscles to exert greater occlusal forces during sleeping hours.

Forces delivered in the axe of the tooth are better tolerated than lateral forces, because stimulating the whole periodontal tissues of the teeth as well as the whole alveolar bone is less traumatic than the lateral forces stimulate just 1/17 of the periodontal tissues and the alveolar bone.

Characteristics.

Forces generated by functional tooth contact has no pathologic effects on the components of the masticatory system, but forces generated by bruxism may affect one element or more of the masticatory system.

Results are affected by resistance of the host, duration, frequency and intensity of the para functional activity.

6. Clinical Consequences. In every individual there is a limit for

physiologic adaptation to imperfection or disharmony in occlusal relationships.

When this limit is surpassed, either because of increased occlusal disharmony or increased CNS tension a hypertonic response in the masticatory muscles follows.

The hypertonic response may be on the basis of facilitation of nervous impulses of occlusal origin and/or lowered threshold of neuron excitability from nervous tension or pain.

Effect of trauma on the masticatory system.

Clinical Consequences.

An increase in neuromuscular activity may lead to injury to the periodontiumperiodontium or the TMJTMJ, or may produce pain and discomfort within the tense muscles.muscles.

Such injury or discomfort will result in increased afferent stimuli to the nerve center of the reflex system, with subsequent tendency for increased efferent activity and increased injurious impact.


It appears that there is no acceptable evidence to show that there is adaptability of the TMJ in adults or even children more than 10 years of age beyond physiologic internal remodeling that occurs in all living bones.

Although the joint where changed temporarily because of the trauma from occlusally induced displacement, adaptive repositioning of the teeth continued until the TMJs returned to their previous relationships.


Results of several studies indicate the need for adapting the occlusion to the joints rather than hoping for the joints to adapt to the occlusion, at least when considering the old TMJ.

It appears that changes which occasionally take place in the TMJ are the result of pathologic processes rather than physiologic adaptation.

The entire dentition undergoes a continuous adaptation to functional wear.


Adjustment of tooth position occurs throughout a person’s lifetime in response to naturally induced changed of occlusal forces associated with wear, in response to pathologic changes in the support mechanism or muscle tonicity, and following placement of restorations and other dental procedures.

However, within the adaptive capacity of the masticatory system, a balance of forces is maintained.


The most clinical consequences of trauma from bruxism is tooth wear as reflected by localized or generalized occlusal or incisal facets or both.

Excessive wear of the anterior teeth result in esthetic concern and restorative challenge.

Severe wear of posterior teeth may cause reduced vertical dimension, mandible over-closure combined with food impaction.

Tooth wear.


Other consequences from bruxism to the dentition and supporting tissues include:

1- Thermal hypersensitivity. 2- Hyper mobility. 4- Injury to periodontal ligament. 5- Hyper cementosis. 6- Pulpitis an pulp necrosis. Resorption of alveolar ridge has been

observed in denture wearer who exhibited bruxist behavior.


Effect on the supporting tissues have intimate relation with the quality of the periodontal structure.

Tooth supra eruption can be noticed with its alveolar bone, which create restorative problem.

Severe trauma may lead to resorption of the cementum and it may extend to the dentin.

Patients with steep cusps may have greater periodontal damage when lateral stress was applied.


Escher and others claimed that periodontal disease predispose an individual to bruxism by increasing the tonus of jaw muscles.

Movement of the teeth associated with gingival and periodontal inflammation may initiate occlusal interferences.

Discomfort associated with inflammation may increase muscle tonus.


Repetitive overloading of the TMJ via the dentition has been suggested as a factor in osteoarthrosis of the TMJ.

Mandibular parafunctional activity is a significant contributor to repetitive overloading.

This activity may cause pain in the TMJ area if the health of the related tissues is compromised. Elements may be involved are retrodiscal, synovial, membranes of the joint capsule and collateral ligaments of the disc-condyle complex.


It’s suggested that clenching involving the anterior dentition cause internal derangement of the TMJ.

But with cusp to cusp contact during eccentric clenching, the articular disk in the ipsilateral TMJ concomitantly is braced by the superior belly of the lateral pterygoid muscle, the head of the condyle moves into latero-trusive direction these excessive forces on the related ligaments of the disk-condyle complex may compromise their structure and cause disk displacement.

Clenching and its effects on the TMJ.


Tenderness to palpation of the masticatory muscles.

Patient may experience masticatory muscle tightnessmuscle tightness and limited muscle limited muscle movement on awaking.movement on awaking.

These muscle dysfunctions may create muscular contraction so that they may create vascular contraction, which develops into possible inflammation,or biochemical changes.

Clinical Consequences. Because oxygen decreases in circulation it cause Because oxygen decreases in circulation it cause

changes of pyruvic acid to lactic acid instead of citric changes of pyruvic acid to lactic acid instead of citric acid which will not allow ADP to go to ATP for energy acid which will not allow ADP to go to ATP for energy formation; thus, the muscular system becomes formation; thus, the muscular system becomes weaker and may end in possible necrosis of tissueweaker and may end in possible necrosis of tissue.

Excessive occlusion overloading, tension will increase and accumulate in the muscles.

A fatigued muscle showed a loss of irritability due to an accumulation of lactic acid.

Constant working of muscles, even when fatigue Constant working of muscles, even when fatigue does not occur, may result in hypertrophydoes not occur, may result in hypertrophy.


It has been showed by Berlin and Dessner and Monica that bruxism may lead to chronic headache. Also the correlation is not entirely clear, it has been postulated by Wolff and others that the basis for the pain or ache is the disturbed circulation in the muscles.

Various type of headache pose very difficult problems in differential diagnosis, since some patients experience headaches associated with muscle tension in the masticatory system.

7. Diagnosis.

Patient arrives complaining of the following symptoms:

A tight sensation of the masticatoryA tight sensation of the masticatory musclesmuscles that usually occurs on on awakingawaking.

MyalgiaMyalgia of the masticatory muscles and myofacial pain.

Hypersensitive teethHypersensitive teeth Sounds generated from grinding the

teeth during sleeping hours reported by a roommate.

Diagnosis.

Clinical signs that the practitioner can observe:

Occlusal and incisal wear of the Occlusal and incisal wear of the dentitiondentition.

Mobility of the teeth that are periodontally compromised.

Fracture of teeth as well as restorations. Hypertrophy of the superfacial belly of Hypertrophy of the superfacial belly of

the masseter musclesthe masseter muscles as well as the anterior temporalis muscles.temporalis muscles.

X ray shows widening of the periodontal ligament space.

Diagnosis.

TendernessTenderness to palpation of the masticatory muscles.

The most obvious sign of nocturnal bruxism is attrition of the incisal edges of the anterior teeth and the occlusal surface of the posterior teeth.

Abrasion during normal mastication or oral habits characterized by facets of opposing teeth that does not align with each other whereas grinding of opposing teeth during bruxism has wear facets that do align.

8. Management.

One investigator suggested that the objectives for management of bruxism should include:

Reduction of psychological stress. Reduction of occlusal irritations. Cessation of neuromuscular habits. Treatment of signs and symptoms of

mandibular parafunction. Because the cause may be multifactorial,

a thorough medical and dental history should be performed.

Management.

Stress management strategy include:

Biofeedback counseling. Relaxation. Hypnosis. Occupational and lifestyle change.

Management.

Direct therapeutic approach to the dentition, musculature and supporting structures include:

Occlusal adjustment. Intra oral orthosis. Pharmacotherapeutic. Physical therapy.

Management.

Occlusal adjustmentOcclusal adjustment is indicated only when there is obvious deflective interference such as:

Supra erupted or mal positioned third molar.

Supra erupted of teeth opposed edentulous area.

Obvious working and non working interferences.

Management.

Inter occlusal appliance includes many types, but with use limitation.

A study reported significant decrease in nocturnal masseter activity after appliance use.

Other study showed; reduced masseter activity in 52%, increased in 20%, unchanged in 28%.

Some other studies showed 80-90% improvement in symptoms despite 50% reduction in bruxing activity.

Management.

The purpose of the intra oral appliance is a simple redistribution of the masticatory forces.

Unloading the TMJ when the retrodiscal tissues are inflamed, therefore, reducing the pressure on the edematous and injured tissues distal to the condyle.

The effectiveness of the orthosis can be enhanced with concomitant use of pharmaceuticals such as NSAIDs.

Effect of different types of splints.

Management.

The inherent design of the appliance should provide:

Redistribution of occlusal forces. Relaxation of the elevator

masticatory muscles. Stabilization of the TMJ. Protection of the dentition. Decrease in symptoms. Reduction of bruxism.

Management.

The design of of stabilization orthosis The design of of stabilization orthosis isis:

A full arch. Acrylic resin. Flat plane orthosis. Can be maxillary or mandibular. Undulation dictated by the occlusal

plane. Flat but if indentations exist it should in

centric bearing cusp and incisal edge of anterior teeth.

Even redistribution of occlusal forces.

Effect of limited anterior bite plane on the TMJ.

Occlusal splint.

Maxillary stabilization bite plane splint.

Management.

Maxillary appliance has the advantages to achieve occlusal contact with the opposing teeth regardless of the maxillo-mandibular relationship which is not possible with the lower appliance, despite that the mandibular appliance is more esthetic and does not affect the phonetics.

Management.

Design of the maxillary appliance; It should be horseshoe shape. Should have clasp on both sides. Acrylic should overlap buccal and labial of the teeth to

prevent any movement. Flat occlusal surface with even contact in centric-

bearing cusp of the posterior teeth as well as the incisal edge of the lower anterior teeth.

Anterior acrylic ramp is to provide disclusion of posterior teeth in the lateral movements.

Management. In an effort to minimize the adjustment

time, an interocclusal record at the desired vertical dimension should be done and which will be used for mounting the opposing cast, so that the appliance will be fabricated at a jaw relationship within the physiologic parameters of the patient.

The clearance between the tow jaws clearance between the tow jaws should never exceed the freeway spaceshould never exceed the freeway space, if not the muscle tone, which is the passive resistance to stretch, will be affected concomitant with fatigue feelings.

Management.

Also adjustment is needed to perform an even contact during habitual closure as well as inhabitual closure as well as in occlusion in CRocclusion in CR so the patient can use it during sleeping time and awaking hours.

It is important to remind that the inerocclusal record should be performed in reclined positionreclined position ( occlusion in CR ).

Management.

The healing phase that follows the appliance therapy shows:

Reduction of pain. Reduction of edema and inflamed

tissues. Reduction of muscle activity. Clinical examination suggests that this

improvement is on a psychology basis. However, these results are on the basis of the even contact in CR occlusion as in CO position.

Management.

Stabilization orthosis is generally worn during increase of muscle activityduring increase of muscle activity, normally at nightnormally at night, but it could be use during waking hours.

Duration of wearing the orthosis can be reduced as signs and symptoms resolvereduced as signs and symptoms resolve.

If the disorder affect just the muscles, using the orthosis during sleeping is to be considered.

If the TMJ is affected (intracapsular disorder) full time wearing the orthosis during the initial stage may be indicated.

Management.

When symptoms are overWhen symptoms are over, using the orthosis is not necessary anymore, but intermittent wearing may be necessary during stressful life events.

At this stage, the muscles are well relaxed, so guiding the mandible in occlusion in different positions will be helpful in finding out the important interferences in a clear way.

Adjustment of these interferences is helpful in the treatment of the signs and the symptoms of bruxism.

Management.

One month useOne month use is enough to expect positive is enough to expect positive patient responsepatient response.

In case where symptoms affect the myofacial and temporal muscles, the anterior flat biteplane is indicated, it is fabricated by hard acrylic and come in contact with just the lower anterior teeth.

It affects brux. and parafunctional behavior. It is effective when the chief complain is

limited to muscle pain. Its use limited on sleeping hours to avoid posterior teeth supra eruption.

Management. Concerning the appliance material; one study

indicated that hard interocclusal orthosis is likely to be more successful than soft orthosis in reducing nocturnal muscle activity as well as myofacial pain symptoms.

Also soft material is more difficult to adjust, and contribute to inadvertent tooth movement and occlusal changes.

However, soft orthosis has certain indications as transitional one for emergency cases and as athletic mouth guard.

Management.

Adjunctive physical therapyAdjunctive physical therapy; it is useful in managing the pain of masticatory muscles related to bruxism, it includes:

Stretch and spray with vapocoolant. Masticatory muscle exercises. Patient awareness of parafunctional

activity. Ultrasound. Trans cutaneous electric stimulation. Heat application.

Management.

For both diagnostic and short management approach, using a pharmaceutical anti anxiety agent is to be considered, diazepam demonstrated good resultsdemonstrated good results.

Antidepressant Antidepressant pharmaceutical agent would suppress the REMREM stage of sleepstage of sleep which has an association with bruxism.

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bruxism, an overview and management

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