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Bruxism (from the Greek βρυγμός (brugmós), gnashing of teeth) is grinding of the teeth, typically accompanied by clenching of the jaw. It is an oral parafunctional activity that occurs to some extent 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.
Bruxism often occurs during sleep and can even occur during short naps. Bruxism is one of the most common sleep disorders: 30 to 40 million Americans grind their teeth during sleep.
The etiology of bruxism is unknown; the following factors may be associated with the condition.
Signs, symptoms and sequelae
Over time, dental damage will usually occur. Bruxism is the leading cause of occlusal trauma and a significant cause of tooth loss and gum recession.
In a typical case, the canines and incisors of the oppsoting arches are moved against each other laterally, i.e. with a side-to-side action by the lateral pterygoid muscles that lie medial to the temporomandibular joints bilaterally. This movement abrades tooth structure, and can lead to the wearing down of the incisal edges of the teeth. People with bruxism may also grind their posterior teeth, which will wear down the cusps of the occlusal surface. Bruxing can be loud enough to wake a sleeping partner. Some individuals will clench the jaw without significant lateral movements.
Eventually, 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.
Most bruxers are not aware of their bruxism and only 5-10% go on to develop symptoms such as jaw pain and headache. Teeth hollowed by previous decay (caries), or dental drilling, may collapse, as the cyclic pressure exerted by bruxism is extremely taxing on the tooth structure.
Bruxism is not the only cause of tooth wear. Over-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.
The effects of bruxing 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 has been 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.
A recently introduced device called the BiteStrip enables at-home overnight testing for sleep bruxism. It is proposed that this 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 formulating a treatment plan. Anyone having major occlusal rehabilitation should be aware that bruxism can easily ruin prosthetic dental work.
There is no accepted cure for bruxism.
Mouthguards and repositioning splints
Ongoing management of bruxism is based on minimizing the abrasion of tooth surfaces by the wearing of an acrylic dental guard or splint, designed to the shape of an individual's upper or lower teeth from a bite mould. Mouthguards are obtained through visits to a dentist for measuring, fitting, and ongoing supervision. There are four possible goals of this treatment: (1) to constrain the bruxing pattern such that serious damage to the temperomandibular joints is prevented; (2) to stabilize the occlusion by minimizing the gradual changes to the positions of the teeth that typically occur with bruxism; (3) to prevent tooth damage; and (4) to enable a bruxism practitioner to judge — in broad terms — the extent and patterns of bruxism, through examination of the physical indentations on the surface of the splint. A dental guard is typically worn on a long-term basis during every night's sleep.
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.
Another type of device sometimes given to a bruxer is a repositioning splint. A repositioning splint may look similar to a traditional night guard, but is designed to change the occlusion, or "bite," of the patient. Randomly controlled trials with these type devices generally show no benefit over more conservative therapies and they should be avoided under most if not all circumstances.
The NTI-tss device is another option that can be considered. The NTI covers only the front teeth and prevents the rear molars from coming into contact, thus limiting the contraction of the temporalis muscle. The NTI must be fit by your dentist.
The efficacy of such devices is debated. Some writers propose that irreversible complications can result from the long-term use of mouthguards and repositioning splints.
There is limited evidence that suggests taking certain combinations of vitamin supplements may alleviate bruxism.
Various biofeedback devices are currently available, but their effectiveness is as yet unproven. While anecdotal evidence suggests that they may be useful, some bruxism authorities remain unconvinced.
One biofeedback mechanism that has significant promise was developed by Moti Nissani, PhD and is called "The Taste-Based Approach to the Prevention of Teeth Clenching and Grinding." The therapy involves suspending sealed packets containing a bad-tasting substance (e.g. hot sauce, vinegar, denatonium benzoate, etc.) between the rear molars using an orthodontic-style appliance. Any attempt to bring the teeth together will rupture the packets and alert the user to the habit. While no cure exists for bruxism, this approach, if implemented properly and rigorously, has promise to be an infinitely effective treatment for bruxism. Importantly, the Taste-Based Approach does not suffer from the risk of desensitization that other available sound-based biofeedback approaches may have. (There is effectively no limit to the aversive taste of certain substances. We can therefore be sure that some harmless substance exists that will alert anyone to the habit.)
One of these devices, the Oralsensor, 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. This device delivers nightly data on (1) the number of bruxism events that last for at least two seconds, and (2) the total duration of those events. The volume of the alarm and the sensitivity of the piezo device to EMG signals from the muscles are adjustable.
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 device forces people to breathe through the mouth; 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.
Meditation and relaxation techniques
Sufferers may find that meditation and relaxation techniques may help to reduce teeth grinding.
Repairing damage to teeth from bruxism
Damaged teeth can be repaired by replacing the worn natural crown of the tooth with prosthetic crowns. 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, full gold crowns are preferred. 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 should be fabricated to wear during sleep.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Bruxism". A list of authors is available in Wikipedia.|