Bruxism is the term used to describe a para-functional (i.e. somewhat abnormal) clenching and/or grinding of the teeth and it occurs quite commonly. It is generally considered to be an expression of tension or stress either subconsciously or consciously. It is possible that sometimes the action begins when a person is in a period of undue mental stress and then continues on as a habit even after the stressful situation is resolved.
In many cases bruxism is fairly mild and hardly noticeable, and it is well known that we all tend to “grit our teeth” when under stress of some kind, but when it continues over a long period of time it can lead on to a multitude of different problems such as: headaches, earache, tinnitus, sleep disturbance, neck pain, eating disorders, temperomandibular joint pain, gum recession, loosening of teeth, and even depression. Bruxism often occurs subconsciously during sleep and is an issue because of possible excess physical stress on the temperomandibular joint and increased wear of the teeth which can be significant. Sometimes it is an issue with a partner because of the noise produced by teeth grinding.
Sometimes bruxist activity is rhythmic in nature, suggesting the acquisition of a muscle pattern that has become established, and treatments will be aimed at breaking that pattern.
If bruxism occurs during sleep it can continue for several hours with considerable pressures being put on the teeth during that time from repeated clenching action and causing significant abrasion of the teeth from lateral movements under pressure. There can be premature wear of incisal edges and cusps of teeth, and in addition, possible cracks or fractures. Teeth already compromised in strength by decay or fillings are more likely to suffer fractures of cusps. Excessive loading of the teeth in those who have marked lateral movements causes rocking of the teeth within their sockets, and this can lead to eventual gum recession and even possible loosening of teeth. It is understandable that over a period of time this can also lead to abnormal stress and strain on facial muscles and the jaw joints with resulting aches and pains.
In a typical case involving lateral motion, the medial pterygoid muscles that lie medial to the temporomandibular joints on each side of the face are involved. Clenching tends to involve the masseter and temporalis muscles, although some people have a lesser habit with less defined muscle action.
During normal chewing the teeth only come into actual contact with each other quite infrequently, but bruxism is a completely different situation where teeth are grinding across each other with no food in between, for extended periods of time, maybe up to several hours during a 24 hour period.
It has been estimated that the amount of pressure placed on teeth during normal functional habits is 20–80 pounds per square inch, but during bruxist habits it can be as much as from 300 to 3000 pounds per square inch depending on the strength of the jaw musculature. Another big difference is that normal biting, and even chewing, mainly directs forces vertically down the long axes of the teeth and they are well able to resist and disperse these, but during bruxism the forces are mainly horizontal and thus can tend to eventually loosen teeth. Bruxism can change the position of the fulcrum that pertains to jaw movement, potentially generating more force from the same degree of muscle activity.
Eventually, bruxism with lateral movements tends to produce symptoms such as myofacial pain and obvious wear of the teeth with increased sensitivity where dentine is exposed, either through enamel wear of the occlusal surfaces or from the exposure of roots due to gum shrinkage. Once dentine is exposed occlusally then the rate of wear accelerates quite dramatically because dentine is softer than enamel, and the situation can worsen fairly rapidly. In severe, extended chronic cases, bruxism can even lead to inflammatory changes and arthritis of the temporomandibular joints.
Bruxism may be diagnosed by a dentist as a result of observed excessive tooth abrasion and a follow up history, but a confirmation of diagnosis may require electromyography (EMG) in order to substantiate. This technique picks up electrical signals from the facial muscles from electrodes on the face or by means of a headband. The measurements from these can help establish the degree of severity of the bruxism habit and can distinguish pure clenching from rhythmic grinding. The units may sometimes be used with a biofeedback mechanism to help extinguish the bruxist habit.
The precise aetiology of bruxism is unclear and indeed may vary in different individuals but it can be associated with other conditions or factors which might be contributory, although they may also simply be resultant to an extent. Disturbed sleep patterns, malocclusions causing premature contacts of posterior teeth, high consumption of alcohol and/or caffeinated drinks, smoking, and high anxiety levels have all been observed in connection with some cases of bruxism.
When bruxism is deemed to be due mainly to stress or depression then antidepressant type drugs may be prescribed such as selective serotonin reuptake inhibitors or other drugs, but often other types of treatment are tried first such as occlusal splints, mandibular advancement devices, or hypnosis. The occlusal splint is often the first line of treatment since it protects the teeth and reduces the troublesome grinding noise. It often helps also to reduce the muscle activity in the face and provides some respite although it may not be enough by itself to actually cure the habit.
Thus behavioural therapies including psychoanalysis, autosuggestion, hypnosis, or bio-feedback systems may be tried.
Common sense suggests that reducing stress in everyday life plus relaxation techniques would be most helpful but the former is not always easy for people in a stressful job or difficult relationship.