Bruxism

The Causes of Bruxism

Bruxism is more of a behavioural disorder than a physical condition per se, except perhaps in cases where an occlusal disharmony may trigger it. A premature contact when the teeth are brought together is thought to be sometimes responsible for setting off a grinding habit. This is occasionally seen when a dentist fills a tooth and the amalgam filling is unintentionally left fractionally high in the bite. Even this small amount of prematurity often triggers a grinding response as the patient tries subconsciously to remove the high spot as can often be seen from the shiny area on the filling that results.

Children sometimes have a tendency to grind their teeth and this is sometimes associated with the permanent teeth erupting although often seems to be for no particular reason at all and doesn’t generally cause any problem although it may sound disturbing. They usually grow out of the habit by the time they reach their teens.

Bruxism in adults is very variable in degree but can cause other problems if pronounced and continuous over a period of time. Many people probably have a very mild bruxing tendency, often with just frequent teeth clenching but no actual grinding, and this causes them little or no bother. The aetiology of noticeable bruxism can be quite varied, from allergic reactions or medical conditions such as digestive problems, to trauma resulting from an accident; but most often seems to be associated with stress or anxiety. Some people have a naturally anxious disposition and may be more likely to develop a teeth clenching or grinding habit. Sometimes it seems that a period of unusually high stress causes the habit to begin and it may persist even after the stressful period has ended. 

Suppressed anger or frustration, or even just an inherently aggressive or hyperactive personality can result in teeth grinding in some individuals and if linked to underlying personality traits may be difficult to manage. Rarely, bruxism is an associated complication of a physical disorder such as Parkinson’s or Huntington’s disease.

Bruxism is possibly most common during sleep and research and observation have shown that it is often associated with certain lifestyle factors or problems. People who have a sleep disturbance problem to a greater or lesser degree often tend to also have a grinding habit. Whether it’s the grinding that keeps them awake is not clear. In addition to actual insomnia there are sleep problems such as disruptive snoring and intermittent sleep apnoea where there are brief periods of not breathing. In these cases the carbon dioxide level in the blood rises and a natural reflex kick-starts breathing again but it can be distressing for some or cause inadequately refreshing sleep with the person then feeling “washed out” the next day. Bruxism is more commonly seen in people who suffer these types of sleep problems.

There is also a recognised association between bruxism and certain lifestyle factors such as heavy use of tobacco, caffeine or alcohol, or the taking of regular medications for anxiety, depression, and insomnia. Certainly also bruxism in some may be linked to a type of antidepressant known as a selective serotonin reuptake inhibitor (SSRI), such paroxetine, fluoxetine and setraline.

Increasingly today many jobs are performance orientated with targets being set and performance levels constantly judged. Some personalities cope better than others in such situations and the need to perform and to be constantly monitored is something that causes many people undue stress, which ironically can lead to them performing even worse!

A thorough history should help in determining the cause of bruxism in any individual case and will include questions about perceived stress levels of the person in their daily life plus lifestyle questions concerning sleeping habits and the intake of various substances such as caffeine and alcohol which are known to possibly exacerbate the situation.

A thorough intraoral examination is also necessary especially in relation to the patient’s occlusion which needs to be carefully assessed for any premature contacts or limitation of excursive movements. Also a check for any tenderness in the muscles of the face needs to be made, and an examination of the teeth for signs of premature wear.

Unfortunately bruxism can persist for years in a person who finds life stressful without any apparent way to reduce their levels of stress. A physical bite problem, though, once diagnosed, is relatively easy to fix by judicious grinding of teeth, orthodontics, or restorative measures, and relief from bruxism usually follows fairly quickly.

The Treatment of Bruxism

Since bruxism is a behavioural problem it can be treated if diagnosed early before much damage has been done by establishing the original cause that triggered the habit and removing the cause, or if it’s chronic stress, by finding alternative ways of dealing with it. Many people today have stressful jobs and this is certainly reckoned to be a prime cause of bruxism in many. Short of changing jobs it may be a case of trying to manage the stress and the bruxism habit even if it cannot be completely cured.

Once the bruxism habit is well established it becomes more difficult to break, but a bite guard or dental splint can help rest facial muscles and may allow amelioration of the underlying muscle patterns whilst at the same time protecting the teeth from further wear, especially if the habit occurs mainly at night when the person is asleep. The form of an occlusal splint or bite guard may vary but it is generally constructed of semi-rigid acrylic and fits over either the upper or lower arch of teeth with a flat top surface to prevent interdigitation of teeth and break an established muscle pattern. It helps to reduce muscle strain by allowing the lower jaw to move freely without being locked into a previously set pattern. It is usually successful in stopping the noise from grinding the teeth and also gives relief to the facial muscles. If muscle tension is relieved it helps reduce strain and damage to jaw joints. The mouthguard or splint has to be worn at night for a considerable period of time in order to provide effective and lasting relief in most cases.

A mandibular advance device has been advocated by some as is used to treat cases of sleep apnoea but the advantages of this over a simple splint are not clear.

If you grind your teeth during the day while awake then it may be possible to keep a diary of when you mostly do it and work out what the causes are; they may be related to work issues for example. Once you are aware of when you start grinding your teeth you can restrain yourself and consciously relax your jaw, training yourself to break the habit. Such habit reversal techniques can be used by those who are strongly motivated to overcome the problem by themselves.

Thus often it may be necessary to use a combination of physical treatments such as a mouthguard or occlusal splint of some kind together with psychological treatments to reduce the underlying stress or anxiety, or in some way to break the habit.

Professional counselling such as psychotherapy may be a help to many by helping them to understand the problem, and there are various techniques such as autosuggestion, relaxation techniques and exercises, hypnosis, biofeedback exercises, and meditation which have all been found to be helpful to varying degrees in many cases.

The principle behind biofeedback is that an undesirable action such as bruxism can be “unlearned” if the person can be constantly alerted when it’s happening. Thus when bruxism occurs, a stimulus to the patient can make them aware of their jaw activity and they can respond by altering their muscular movements. This of course is only likely to work whilst the person is conscious during the daytime and is of dubious value at night-time. There is however, at least one device that uses a headband and emits an increasing audio signal when clenching is detected, but evidence of its effectiveness is not that convincing.

Another biofeedback based option is a nociceptive trigeminal inhibitor type of mouthguard which aims to translate attempts at clenching to forward posturing of the jaw, but the effectiveness of this is highly debatable and it may not be a desirable objective even if it works.

If a dental problem such as a malocclusion or a premature contact with jaw deviation is diagnosed then of course treatment is aimed at rectifying the situation and this might require specialist orthodontic, restorative or even surgical treatment in some instances.

Any underlying medical conditions need to be recognised and addressed, and they might include neural problems or problems related to taking certain drugs such as antidepressants.

Medication is not usually the main thrust of treatment for bruxism but can be helpful to a degree. Muscle relaxants may help to temporarily relieve the spasm and thus rest the jaw joints giving some relief of symptoms, and even botulinum injections have been used to reduce facial muscle contractions in some cases. Botulinum toxin or Botox can be used in very dilute form to partially paralyze the facial muscles, particularly the masseter which is mainly responsible for jaw movements. The treatment may need to be repeated, and the concern must be to get the correct degree of effect on the muscles without overdoing it! The other problem is that if the muscles are not used very much over a long period of time they are likely to atrophy, so this also needs to be taken into account.

Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can help relieve inflammation and pain in and around the jaw joints, although it is not advisable to continue taking them for too long. If bruxism is diagnosed as a side effect of certain medications such as antidepressants then it may be necessary to change the prescription.

There is some evidence that certain dietary supplements may help alleviate bruxism, and the main ones mentioned are calcium, magnesium, and pantothenic acid. Their effectiveness, however, is not really established.

Restorations need to be adequately strong so may be best made from gold or porcelain fused to metal. It is probably wise to also provide a mouthguard or occlusal splint to protect the new restorations from damage during sleep.

Any damage to the teeth from excessive wear needs to be addressed as part of the overall treatment of bruxism and may entail considerable amounts of restorative dental work. It is probably best to delay definitive restorations however until the actual bruxist habit has been eliminated or at least considerably reduced, and then there is the problem of establishing the correct occlusal relationships where vertical dimension has been lost from attrition.

Treatment of Teeth Damaged by Bruxism

Once the bruxism habit is controlled, often by the use of an occlusal splint, it is necessary to turn attention to repairing the damage to the dentition which of course can be of varying degree depending on the severity of the habit and the length of time it has being going on. If the situation is left uncontrolled it inevitably leads to damage to teeth from progressive abrasion, with cracks eventually appearing which can develop into fractures causing large parts of teeth to be lost. This can lead to death of the pulp of a tooth and a subsequent abscess developing. The larger the chunk of tooth lost the more difficult it is to restore, and especially so if the fracture line extends subgingivally. If a tooth splits down the middle then there is usually little choice but to extract it.

Restoration of teeth damaged by bruxism is aimed at reconstituting the form of the crown of the tooth and its strength as far as possible, and also at protecting the teeth from further damage. An individual tooth may require an inlay, onlay, or crown, perhaps with prior root treatment in some cases. Missing teeth can be restored with removable or fixed prostheses, or implants. The degree of complexity of treatment obviously depends on the extent of the damage that has taken place.

If bruxism may be related to occlusal disharmony then an analysis of the occlusion needs to be undertaken prior to providing definitive restorations and sometimes provisional build-ups with composite are used to gradually establish a proper and comfortable bite. This may follow on from the preliminary treatment with a mouthguard aimed at deterring the bruxist habit and resting the temperomandibular joints.

Definitive restorations need to be adequately strong, so gold alloy is the best choice for posterior teeth. Porcelain fused to gold provides for a more aesthetic result but may necessitate removal of more tooth substance which may be clinically contra-indicated. The latest types of porcelain onlays and crowns are pretty strong, especially those produced from solid blocks of porcelain as in the CEREC system, and thus may be considered, since they can be bonded well to tooth substance and can thus be used where there is a flattish tooth surface to restore as a result of abrasion coupled with erosion of a molar.

Where loss of tooth substance has been considerable there may be the need to involve several dental procedures. Teeth that are worn down to near gum level will probably need a post to be inserted for adequate retention of a crown and thus endodontic treatment must be carried out first. Consideration may also be given to crown lengthening procedures in some cases.

Patients who have bruxism without significant lateral jaw movements may wear the anterior teeth excessively rather than the posteriors, and in these circumstances the lower incisors continue to erupt but are continually worn down again often changing the occlusion and introducing a marked overbite.

This situation can be difficult to treat and one approach might be to open the bite in order to get sufficient space to enable the restoration of the lower incisors to their proper length. This would, however necessitate restorations to the posterior teeth even though they were relatively unaffected by abrasion.

An alternative might be to orthodontically re-intrude the mandibular incisor teeth so that they can then be restored to their original length without too much tooth preparation. Some crown lengthening may be required either before the orthodontic treatment in order to allow for the fixing of brackets or indeed afterwards to achieve sufficient height for the crown core. The evidence suggests that alveolar bone moves appropriately as a tooth is intruded or extruded and thus an adequate marginal integrity is maintained. There is a potential risk of some root resorption but in practice this does not seem to be a real problem. Also it seems that that patient’s vertical dimension stays the same, in spite of the extrusive force on the posterior teeth during incisor intrusion so long as it’s just a few millimetres. After the orthodontist has successfully intruded the teeth, the restorative dentist should stabilize them with provisional restorations such as acrylic crowns or by using bonded composite. A mouthguard to wear at night helps prevent further tooth wear and maintains the vertical position of the lower incisors long term.

There is no doubt that the patient presenting with gross tooth abrasion as a result of a long term bruxist habit can be quite a challenge for the dentist who needs to take adequate stock of the situation before diving in and may need the help of other specialities in overcoming the several problems inherent in the situation.