Jaw-clenching habit affects teeth and joints
Tooth grinding – or bruxism – is common. Many experts suggest that it affects almost everyone at some time in their life. It seems to affect children more often than adults and many of them grow out of it by adolescence.
Bruxism is the habit of clenching, gnashing or grinding the teeth together. It can happen consciously or unconsciously; when the person is awake, or while asleep. Many people are unaware that they are ‘bruxers’ and it is not uncommon for a person sleeping in the same room to be the first to notice the noise – sometimes described as akin to the sound of ‘nails down a chalk-board’.
For many people tooth grinding is temporary; it stops by itself and causes no long-lasting problems. Longer-term bruxism, though, can lead to other problems and may need treatment.
Signs and symptoms of tooth grinding include:
- tooth grinding that can be heard by others
- worn, flattened, cracked or chipped teeth
- sensitive teeth
- tension or pain in the jaw joint
- enlarged jaw muscles
- earache
- headache
- facial pain
- sinus pain
- tinnitis (ringing in the ear)
- neck, shoulder or back pain
- poor quality sleep or insomnia
- waking tired and daytime tiredness.
Problems caused by tooth grinding
If tooth grinding continues for a long time, it can:
- damage teeth and expose dentine
- generate chronic headaches
- lead to problems with the temporomandibular joint (where the jaw joins the temple) also known as the TMJ
- cause arthritis of the temporomandibular joint.
Diagnosing bruxism
It is not always easy to identify tooth grinding, as many other conditions can cause similar symptoms. Often the grinding habit is quite advanced before it is diagnosed. For example teeth that are worn away to expose dentine may be pointed out by your dentist, leading him to explore tooth grinding as a possible cause.
If the tooth grinding is happening at night, the most reliable way of diagnosing it is to visit a dentist. Grinding leaves a characteristic wear pattern on the teeth, and the dentist can make a plate to wear at night, into which the patient can grind while asleep. This will also record the extent of nocturnal grinding. A more advanced way is through an electromyograph (EMG). Electrodes or a head band are placed on the face near the chewing muscles. They pick up the electrical signals the muscles emit when they clench. This gives an indication of how active the muscles are when the person sleeps. EMG can be done in a sleep laboratory, but some machines can also be used at home.
Factors that may contribute to bruxism
A number of underlying issues have been associated with tooth grinding:
Treatments for bruxism
The choice of treatment for tooth grinding depends on the underlying cause.
Mouth guard
Your dentist can make a mouth guard for you to wear at night, to act as a ‘shock absorber’; minimising the damaging effect of grinding on your teeth.
Correct misaligned teeth
If your teeth are not biting together evenly, this can be addressed by a dentist. He or she may polish the teeth to change the surface, or may realign the teeth using a plate, or a splint. A plate is an orthodontic device that is moulded to fit the shape of the person’s mouth and works by gently pressing teeth into a new position. A splint looks much like a mouth guard. It is designed to change the way the teeth bite together and, like the plate, is made to fit the individual shape of the person’s mouth.
Manage stress
Bruxism that is caused by stress, depression or anger is treated by addressing the cause of the stress. The person may benefit from counselling or relaxation techniques, for example. A child with bruxism may find that discussing his fears before bed helps him to relax.
Behaviour therapy
To address the habitual aspect of tooth grinding, behaviour therapy may be helpful. This involves making the person more aware of their jaw-clenching habit and to find ways to avoid it.
Some EMG equipment provides biofeedback, signalling each jaw-clench with a light, a sound or, in one example, a mild electric shock. This alerts the person to his habit and helps him to correct it.
Botulinum toxin (BOTOX)
Botulinum toxin is used only in people who are troubled by persistent bruxism and its long term effects are still under investigation. The toxin (in a highly diluted form) is injected into the masseter muscle of the jaw. The aim is to weaken this muscle sufficiently to reduce bruxism, while not affecting the person’s ability to chew or speak.
Some local bruising may occur and each treatment wears off after around three months. Some concerns were raised in early 2008 about the possibility that botulinum toxin may be absorbed into the body and even reach a person’s brain. It is thought that repeated doses increase this risk. These long term effects are still being investigated.
Tooth reconstruction
To repair damage caused by bruxism, your dentist may rebuild teeth using fillings, overlays or crowns. However, if the cause of the tooth grinding is not addressed, this is unlikely to provide a permanent solution, and damage is likely to reappear.
Original material prepared by everybody. Reviewed by Prof Jules Kieser, Faculty of Dentistry, University of Otago. November 2009.
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