Bruxism

Bruxism is the grinding of the teeth, typically accompanied by the clenching of the jaw. It is an oral parafunctional activity that occurs in most humans. Bruxism is caused by the activation of reflex chewing activity; it is not a learned habit. Chewing is a complex neuromuscular activity that is controlled by reflex nerve pathways, with higher control by the brain. During sleep, the reflex part is active while the higher control is inactive, resulting in bruxism. In most people, bruxism is mild enough not to be a health problem; however, some people suffer from significant bruxism that can become symptomatic.

The aetiology of bruxism is unknown, but may include asymmetrical occlusion, anxiety, digestive problems, a disturbed sleep pattern, or hypersensitivity of the dopamine receptors in the brain.

Bruxism can cause indentations in the teeth, wear of the biting surface, abfractions and cracks in the teeth. This type of damage is categorised as symptomatic of an occlusal disease.

Bruxism often occurs during sleep and can even occur during short naps. In a typical case, the canines and incisors are moved against each other laterally, i.e. with a side-to-side action by the lateral pterygoid muscles that lie above and to the sides behind the mouth. This lateral movement abrades tooth enamel, removing the sharp biting surfaces and flattening the edges of the teeth.

People with bruxism sometimes also grind the molars together, which can be loud enough to wake a sleeping partner. Some will clench without significant side-to-side jaw movement. Bruxism is one of the most common sleep disorders: Given enough time, dental damage will usually occur. Bruxism is the leading cause of occlusal disease and a significant cause of tooth loss.

Over time, bruxing shortens and blunts the teeth being ground, and may lead to myofacial muscle pain and headaches. In severe, chronic cases, it can lead to arthritis of the temporomandibular joints (the joints of the jaw). Most people are not aware of their bruxism and only 5 to 10 percent go on to develop symptoms such as jaw pain and headache. Teeth hollowed by previous decay (caries) may collapse as the pressure exerted by bruxism on the teeth is extraordinarily high.

A recently introduced device called the BiteStrip enables at-home overnight testing for sleep bruxism and might help diagnose bruxism before damage appears on the teeth. The device is a miniature electromyograph machine that senses jaw muscle activity while the patient sleeps. A dentist can establish the frequency of bruxing, which helps in choosing a treatment plan. Anyone having major occlusal rehabilitation should be aware that bruxism can and does ruin dental work.

The effects of the condition may be quite advanced before sufferers are aware they brux. Abraded teeth are usually brought to the patient's attention during a routine dental examination. If enough enamel is abraded, the softer dentine will be exposed and abrasion will accelerate. This opens the possibility of dental decay and tooth fracture--and in some people, gum recession. Early intervention by a dentist is advisable.

Bruxism is not the only cause of tooth wear. Overly vigorous brushing, abrasives in toothpaste, acidic soft drinks and abrasive foods can also be contributing factors; each has characteristic wear patterns that a trained professional can identify.

Bruxism caused by drug use

Some drugs are known to cause bruxism as a side effect, e.g. MDMA and others of the amphetamine-based family. Drug users who experience bruxism often refer to the grinding of teeth as "gurning."

Excessive use (i.e. frequent redosing and dependancy) of GHB and similar GABA inducing analogues such as Phenibut are also known to cause bruxism.

Treatment of bruxism

There is no accepted cure for bruxism. Ongoing management of bruxism is based on minimizing the abrasion of tooth surfaces by the wearing of an acrylic dental guard, designed to the shape of an individual's upper or lower teeth from a bite mould. Mouthguards are traditionally obtained through visits to a dentist for measuring, fitting, and ongoing supervision.

Custom-fitted mouthguards are also available by mail, using home dental moulds, and non-custom mouthguards are available at drug stores in some countries. However, professional treatment is medically recommended to ensure proper fit, make ongoing adjustments as needed, and check that the occlusion (bite) has remained stable. Monitoring of the mouthguard is suggested at each dental visit. Serious and irreversible complications can result from long term use of mouthguards.

The main goal of treatment is to prevent further tooth damage, and requires that the night guard be worn as long as the person has teeth.

There is limited evidence that suggests taking certain combinations of vitamin supplements may alleviate bruxism.
One way of stopping the damage and severity of grinding and clenching is through the making of a repositioning splint. A repositioning splint looks like the traditional night guard, but has certain functions built into it. This device supposedly not only protects the teeth when grinding, but also reduces the urge to grind. The efficacy of such devices is unproven.

Several biofeedback devices are available that, as of 2007, are as yet unproven in effectiveness. While there is anecdotal evidence that they are of some use, there are detractors among bruxism professionals. One of these devices is the Oralsensor, which comprises a pneumatic pouch embedded in a soft polymer plate that fits over upper or lower teeth. When the teeth come together—to a threshold pressure set each night by the user—an alarm is sounded in an earpiece worn by the user.

Another biofeedback device, GrindAlert, is a battery-powered device that sounds a tone when it senses EMG (electromyographic) muscle activity in the temporalis muscles of the forehead. In 2005, a new type of occlusive device was patented that produces a movement incompatible with teeth clenching. When nighttime bruxism occurs, people breathe through the nose. The new device forces people to breathe through the mouth; thus, by forcing the opening of the mouth, the device is claimed to stop clenching.

The occlusive device has an electromyogram system that monitors the electric activity of the jaw muscle via wireless electrodes. These electrodes transfer jaw-muscle activity by radio frequency to an external monitoring system. Once the signal has been interpreted by the monitoring system, if a patient clenches (i.e., if the signal transmitted by the electrodes is higher than a given threshold), the monitoring unit sends a radio frequency signal to a transceiver integrated in a mechanical actuator.

The mechanical actuator has two occlusive flaps that block the nostrils, forcing breathing to occur through the mouth. Once the patient stops clenching (i.e., once the signal is under the threshold), the flaps open, allowing breathing through the nose again. The occlusive device does not wake up people since it blocks nostrils slowly, and it never closes them completely to avoid sleep disruption.

Repairing damage to teeth from bruxism

Damaged teeth can be repaired by replacing the worn natural crown of the tooth with an artificial crown. Materials used to make crowns vary; some are less prone to breaking than others, and can last longer. Porcelain fused to metal crowns may be used in the anterior (front) of the mouth; in the posterior (back) gold is the preferred material. All porcelain crowns are now becoming more and more common and work well for both anterior and posterior restorations. To protect the new crowns and dental implants, an occlusal guard may be fabricated to wear during sleep.

Sufferers may find that meditation and relaxation techniques, like any other tactic to reduce stress, may help to reduce teeth grinding.