Understanding Bruxism

By Dr Heather Muir / 24 Sep 2020

Dr Heather Muir details the classifications and treatment options for teeth clenching and grinding

Bruxism is a movement disorder of the masticatory muscles associated with tightening or grinding of the teeth.

An expert group defined bruxism as a repetitive jaw muscle activity, characterised by clenching or grinding of the teeth and/ or by bracing or thrusting of the mandible.1 Bruxism is a common condition with an adult prevalence ranging between 8-31% within the general population.2 It is clinically relevant owing to its association with tooth abrasions and mobility, fracture of dental restorations and teeth, hypertrophy of the masseter muscle and myalgia or arthralgia characteristic of temporomandibular disorders (TMD).3-5

TMD are the second most common causes of orofacial pain, with dental pain as the first, recognised by pain in the temporomandibular joint region and in the facial muscles. As well as pain, patients may experience other signs and symptoms, such as clicking of the joint and trismus (restricted mouth-opening). The prevalence of the population who have TMD symptoms to some degree is 5-12%, which varies by age group and gender.6

Bruxism is a disorder of multifactorial origin and may require several treatments to alleviate the symptoms and manage the disorder. Aesthetic practitioners are in an ideal position to treat this with the use of botulinum toxin or make a diagnosis and/or refer. The clinician needs an understanding of the condition, the treatments available to offer, and the approaches for successful treatment.

Classifications

Bruxism can be subclassified into primary or secondary types. Primary bruxism is not related to any other medical condition, whereas secondary bruxism is associated with either neurological disorders or an adverse effect of medication. It may have two distinct manifestations: sleep bruxism, which is also known as nocturnal bruxism, or awake bruxism, also known as diurnal or wakeful bruxism.7

Sleep bruxism

Sleep bruxism is a masticatory muscle activity during sleep that is characterised as rhythmic (phasic) or non-rhythmic (tonic) and is neither a movement disorder nor a sleep disorder in otherwise healthy individuals.1 Sleep bruxism does not show gender prevalence.8 It is estimated globally that sleep bruxism affects 16% of the population,9 however the prevalence of sleep bruxism among children and adolescents is often higher and can be from 3-49%.10 The exact aetiopathogenesis of sleep bruxism is not fully understood.11 There are many different factors believed to be associated with this muscular activity.12 An increasing amount of evidence suggests a relationship between sleep bruxism and other disorders or systemic diseases, including reflux disease, sleep breathing disorders, uncontrolled limb movements during sleep and neurological disorders.13

Awake bruxism

Awake bruxism is a masticatory muscle activity during wakefulness that is characterised by repetitive or sustained tooth contact and/or by bracing or thrusting of the mandible. It is not a classed as movement disorder in otherwise healthy individuals.1 Awake bruxism is more prevalent in females than males8 and affects 24% of the adult population.9

Aetiology

In general the aetiology and pathophysiology of bruxism are not fully understood. Several factors have been proposed, such as emotional stress, neurological disorders, certain drugs and occlusal interferences.14,15 It seems to have a multifactorial origin mediated by the central and autonomous nervous systems.16,17 The aetiology of bruxism can be divided into three groups; psychosocial factors (stress, anxiety and depression), peripheral factors (such as occlusal discrepancies and anatomy of the bony structures of the orofacial) and pathophysiological factors (such as sleep arousal response).7

Impact on the patient

A study by Lal and Weber included a good summary outlining the indications for the treatment of bruxism as follows:7

  • Tenderness and stiffness in jaw muscles
  • Increased wear of tooth resulting in loss of occlusal morphology and flattening of the occlusal tooth surface
  • Tooth fractures and recurrent fracture of restorations such as class I and class II restorations, fracture of crowns and fixed partial prosthesis
  • Unpleasant loud noise during sleep, which causes disturbances and can awaken the partner
  • Limited mouth opening
  • Pain in the preauricular region
  • Clicking and tenderness of the temporomandibular joint
  • Headaches occur as a result of muscle tenderness associated with the temporalis muscle
  • Cosmetic appearance of hypertrophic masseter muscle and/or hypertrophic temporalis muscle are dissatisfactory for the patient

The management of bruxism relies on the recognition of the potential causative factors associated with its development. Awake bruxism may be confounded by stress and other psychosocial parameters. This form of bruxism can be managed by considering interventions such as habit modification, relaxation therapy and biofeedback. Awake bruxism can often be effectively eliminated via intervention, however recurrence of the condition is common.7

In patients with sleep bruxism (which does not appear to be impacted by psychological or psychosocial factors), appropriate intervention might include appliance therapy and medication. The healthcare provider managing bruxism must understand that nocturnal or sleep bruxism is not usually cured by intervention, however the behaviour is likely to diminish with age.18

In patients with medication or drug-induced bruxism, medication withdrawal or a change of type of medication to a less likely cause of bruxism should be considered. Other factors to consider would be dietary, when there is an excessive consumption of caffeine, or tobacco use.

Treatment

Various treatments have been investigated, however none have been shown to be completely effective. This may be owing to the fact that they are mainly managing the signs and symptoms and to limit damage to the dentition, rather than the cause. Multifactorial treatments may be a better approach involving occlusal correction, behavioural changes and a pharmacological approach such as occlusal splints, cognitive behavioural therapy and benzodiazepines.19,20

Splints

Night guards, occlusal splints, removable appliances or interocclusal orthopedic appliances, as well as customised appliances can be used for the treatment of bruxism. Occlusal splints are generally to prevent tooth wear and tooth injury, while reducing clenching. Removable splints are worn at night to guide the movement to reduce periodontal damage. Splint use should result in a reduction in increased muscle tone. Appliances vary in appearance and features and can be constructed in the dental surgery or a laboratory, and fabricated from hard or soft material. Appliances typically, but not always, cover either all of the maxillary or mandibular teeth.21 Riley et al.’s systematic review concluded that there is no evidence to support the use of oral splints for either bruxism or TMD, based on the results found. Furthermore the type of splint, diagnostic criteria or outcome factors did not change this outcome.22 The efficacy of splints may be in doubt, however there is data which supports their effectiveness as an adjunct for pain management as patients’ perception of their effectiveness is generally positive.23 Their use should be limited to prevent dental damage and to manage the habit.

Occlusal adjustments

Premature contacts or occlusal interferences can be corrected by coronoplasty – where some enamel is removed from the tooth surface. Before occlusal adjustment, muscles should be brought back to their relaxed position for the jaw to resume its normal physiologic movements. This is carried out by biannual manipulation of the temporomandibular joints to return the occlusion to its centric relation.24,25

Psychotherapy

If the cause of the bruxism is thought to be stress, then psychotherapy can be used to aid calmness. Patient counselling, mindfulness, relaxation techniques and cognitive behavioural therapy can lead to a decrease in tension and also create awareness of the habit, thereby reducing symptoms. This results in an increase in the voluntary control and thus can aid in reducing parafunctional movements. However, there is a need for further good quality large scale studies in this area and referral pathways for this treatment type.26,27

Physical therapy

Physical therapy is recommended if bruxism is associated with muscle pain and stiffness. Manipulation can be carried out by a chiropractor or physiotherapist to reduce tension in the muscles around the head and neck area. This can be both preventative and to alleviate the symptoms of bruxism.28

Pharmacological

Pharmacological management includes antianxiolytic drugs, tranquillisers, sedatives and muscle relaxants (both injectable and oral). For example, diazepam can be prescribed for a few days to alter the sleep arousal and anxiety, while low doses of tricyclic antidepressants may be used to inhibit the amount of REM sleep.29 Patients and practitioners often prefer pharmacological treatment to be as short as possible and to treat the acute symptoms of the condition. The other treatments are used more for long-term solutions.

Biofeedback

Biofeedback consists of electronics mounted in a headband with feedback given via an earphone worn by the patient. The patient can view an electromyography (EMG) monitor while the mandible is postured with a minimum of activity. The headband picks up EMG voltage signals indicative of bruxism. Positive feedback is then used to enable the patient to learn tension reduction. Positive results have been described, however larger scale studies are required.30

Electrical method

Electrogalvanic stimulation can be used for muscle relaxation.31 Somatoemotional release (SER) therapy aims to release emotional issues or memories within its tissues.32 Pulsed electromagnetic field (PEMF) therapy has a dual effect on muscle and produces heating and molecular resonance (vibration) with resultant muscle lengthening and reduction of ischemia.33

Equilibration therapy

Bruxism may be due to malocclusion – teeth misalignment. The malocclusion can be corrected using orthodontic treatment.

Acupuncture

Acupuncture has been used to treat awake and sleep bruxism. Research has shown improvements, however as with other treatments further long-term studies are required.34

Botulinum toxin

Kumar et al. proposed that botulinum toxin represents a possible option for the management of sleep bruxism. Botulinum toxin was shown to reduce the frequency of bruxism episodes, masticatory force, muscle mass and decreased pain.35 Fernandez-Nunez et al.’s systematic review consisting of 188 patients concluded the use of botulinum toxin is a safe and effective treatment for patients with bruxism. They also concluded that it showed better clinical results than occlusal splints, drugs or cognitive-behavioural therapy and that its use would be justified in clinical practice.36 Note that the studies in the review were not directly comparable. There are few studies which describe the use of botulinum toxin for the use of awake bruxism, however its use would be identical for both in reducing the contraction of the masseter muscle.37

In my practice, botulinum toxin is a treatment which I commonly provide for bruxism, with patients often being referred from my dental colleagues (see case study as example).

Conclusion

Bruxism is a condition generally of multifactorial origin which can be treated with various treatment modalities. Kumar et al. concluded that bruxism may be better treated with botulinum toxin than splints which is more often than not a dentist’s first treatment modality of choice for bruxism.31 It is for this reason that aesthetic practitioners with an understanding of bruxism should be able to offer this treatment to patients. As it is a disorder of multifactorial origin it may not be the only treatment which should be used and therefore the clinician needs an understanding of the other


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