Bruxism is excessive teeth grinding or jaw clenching. It is an oral parafunctional activity; i.e., it is unrelated to normal function such as eating or talking. Bruxism is a common behavior; the global prevalence of bruxism (both sleep and awake) is 22.22%. Several symptoms are commonly associated with bruxism, including aching jaw muscles, headaches, hypersensitive teeth, tooth wear, and damage to dental restorations (e.g. crowns and fillings). particularly the masseter muscle.
- Tenderness, pain or fatigue of the muscles of mastication,
- Clicking of the temporomandibular joints.
- Tooth fractures,
- Hypersensitive teeth, Others suggest that there is no strong association between TMD and bruxism. In severe, chronic cases, bruxism can lead to myofascial pain and arthritis of the temporomandibular joints.
Tooth wear
Many publications list tooth wear as a consequence of bruxism, but some report a lack of a positive relationship between tooth wear and bruxism.
Tooth mobility
The view that occlusal trauma (as may occur during bruxism) is a causative factor in gingivitis and periodontitis is not widely accepted. It is thought that the periodontal ligament may respond to increased occlusal (biting) forces by resorbing some of the bone of the alveolar crest, which may result in increased tooth mobility, however these changes are reversible if the occlusal force is reduced.
Ankyloglossia is suspected as a cause of bruxism.
Some bruxism activity is rhythmic with bite force pulses of tenths of a second (like chewing), and some have longer bite force pulses of 1 to 30 seconds (clenching). Some individuals clench without significant lateral movements. Bruxism can also be regarded as a disorder of repetitive, unconscious contraction of muscles. This typically involves the masseter muscle and the anterior portion of the temporalis (the large outer muscles that clench), and the lateral pterygoids, relatively small bilateral muscles that act together to perform sideways grinding.
Multiple causes
The cause of bruxism is largely unknown, but it is generally accepted to have multiple possible causes. Bruxism is a parafunctional activity, but it is debated whether this represents a subconscious habit or is entirely involuntary. The relative importance of the various identified possible causative factors is also debated.
Awake bruxism is thought to be usually semivoluntary, and often associated with stress caused by family responsibilities or work pressures. but also possibly grinding, It has been shown that the majority (86%) of sleep bruxism episodes occur during periods of sleep arousal. It has been reported that persons with bruxism respond differently to depression, hostility and stress compared to people without bruxism.<!-- although no genetic markers have yet been identified. Examples may include dopamine agonists,<!-- and is the meeting of teeth during biting and chewing. The term does not imply any disease. Malocclusion is a medical term referring to less than ideal positioning of the upper teeth relative to the lower teeth, which can occur both when the upper jaw is ideally proportioned to the lower jaw, or where there is a discrepancy between the size of the upper jaw relative to the lower jaw. Malocclusion of some sort is so common that the concept of an "ideal occlusion" is called into question, and it can be considered "normal to be abnormal".
- Cerebral palsy (possibly due to long-term therapy with levodopa causing dopaminergic dysfunction)
- Trauma, e.g. brain injury<!-- Bruxcore,
The Individual (personal) Tooth-Wear Index was developed to objectively quantify the degree of tooth wear in an individual, without being affected by the number of missing teeth.
Several devices have been developed that aim to objectively measure bruxism activity, either in terms of muscular activity or bite forces. They have been criticized for introducing a possible change in the bruxing habit, whether increasing or decreasing it, and are therefore poorly representative to the native bruxing activity. People with bruxism are called bruxists or bruxers and the verb itself is "to brux". There is no widely accepted definition of bruxism.
According to the 2025 consensus update on bruxism definitions, experts revised and clarified existing terminology to reduce confusion among clinicians, researchers, educators, and patients. The consensus removed the phrase “in otherwise healthy individuals” from the definitions of both sleep bruxism and awake bruxism, as it was considered unnecessary and potentially misleading. Additionally, the hierarchical grading system for bruxism assessment was revised to incorporate classifications based on self-reports, clinical examination, and device-based assessment methods. The updated consensus recommends using standardized terminology to improve communication and ensure consistency in future research and clinical practice. This is the most widely used classification since sleep bruxism generally has different causes to awake bruxism, although the effects on the condition on the teeth may be the same. and is also termed "diurnal bruxism", The ICDS-R defined sleep bruxism as "a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep", To describe bruxism as a purely somatoform disorder does not reflect the mainstream, modern view of this condition (see causes).
Classification by severity
The ICSD-R described three different severities of sleep bruxism, defining mild as occurring less than nightly, with no damage to teeth or psychosocial impairment; moderate as occurring nightly, with mild impairment of psychosocial functioning; and severe as occurring nightly, and with damage to the teeth, temporomandibular disorders and other physical injuries, and severe psychosocial impairment. it has been recommended that only conservative treatment which is reversible and that carries low risk of morbidity should be used. Relaxation and tension-reduction have not been found to reduce bruxism symptoms, but have given patients a sense of well-being. One study has reported less grinding and reduction of muscle activity, as measured by electromyogram (EMG) after hypnotherapy.
Other interventions include relaxation techniques, stress management, behavioural modification, habit reversal and hypnosis (self hypnosis or with a hypnotherapist). In many cases awake bruxism can be reduced by using reminder techniques. Combined with a protocol sheet this can also help to evaluate in which situations bruxism is most prevalent.
Medication
Many different medications have been used to treat bruxism,
Specific drugs that have been studied in sleep bruxism are clonazepam, levodopa,
Prevention of dental damage
Bruxism can cause significant tooth wear if it is severe, and sometimes dental restorations (crowns, fillings etc.) are damaged or lost, sometimes repeatedly. and complex bridgework for example are relatively contraindicated in bruxists.
Furthermore, occlusal splints are probably ineffective for awake bruxism,
A repositioning splint is designed to change the patient's occlusion, or bite. 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. Random controlled trials with these type devices generally show no benefit over other therapies.
Another partial splint is the nociceptive trigeminal inhibition tension suppression system (NTI-TSS) dental guard. This splint snaps onto the front teeth only. It is theorized to prevent tissue damages primarily by reducing the bite force from attempts to close the jaw normally into a forward twisting of the lower front teeth. The intent is for the brain to interpret the nerve sensations as undesirable, automatically and subconsciously reducing clenching force. However, there may be potential for the NTI-TSS device to act as a Dahl appliance, holding the posterior teeth out of occlusion and leading to their over-eruption, deranging the occlusion (i.e. it may cause the teeth to move position). This is far more likely if the appliance is worn for excessive periods of time, which is why NTI type appliances are designed for night time use only, and ongoing follow-ups are recommended.
A mandibular advancement device (normally used for treatment of obstructive sleep apnea) may reduce sleep bruxism, although its use may be associated with discomfort.
Botulinum toxin
Botulinum neurotoxin (BoNT) is used as a treatment for bruxism.
Botulinum toxin causes muscle paralysis/atrophy by inhibition of acetylcholine release at neuromuscular junctions. BoNT injections are used in bruxism on the theory that a dilute solution of the toxin will partially paralyze the muscles and lessen their ability to forcefully clench and grind the jaw, while aiming to retain enough muscular function to enable normal activities such as talking and eating. This treatment typically involves five or six injections into the masseter and temporalis muscles, and less often into the lateral pterygoids (given the possible risk of decreasing the ability to swallow) taking a few minutes per side. The effects may be noticeable by the next day, and they may last for about three months. Occasionally, adverse effects may occur, such as bruising, but this is quite rare. The dose of toxin used depends upon the person, and a higher dose may be needed in people with stronger muscles of mastication. With the temporary and partial muscle paralysis, atrophy of disuse may occur, meaning that the future required dose may be smaller or the length of time the effects last may be increased.
Biofeedback
Biofeedback is a process or device that allows an individual to become aware of, and alter physiological activity with the aim of improving health. Although the evidence of biofeedback has not been tested for awake bruxism, there is recent evidence for the efficacy of biofeedback in the management of nocturnal bruxism in small control groups. Electromyographic monitoring devices of the associated muscle groups tied with automatic alerting during periods of clenching and grinding have been prescribed for awake bruxism. Dental appliances with capsules that break and release a taste stimulus when enough force is applied have also been described in sleep bruxism, which would wake the person from sleep in an attempt to prevent bruxism episodes.
In 610, Zhubing yuanhou lun by Chao Yuanfang documented the definition of bruxism (齘齒) as "the clenching of teeth during sleep" and explained that it was caused by Qi deficiency and blood stasis. In 978, Taiping Shenghuifang by Wang Huaiyin gave a similar explanation and three prescriptions for treatment.
"La bruxomanie" (a French term, translates to bruxomania) was suggested by Marie Pietkiewics in 1907. Generations of dentists were educated by this ideology in the prominent textbook on occlusion of the time, however therapy centered around removal of occlusal interference remained unsatisfactory. The belief among dentists that occlusion and bruxism are strongly related is still widespread, however the majority of researchers now disfavor malocclusion as the main etiologic factor in favor of a more multifactorial, biopsychosocial model of bruxism.
Society and culture
Clenching the teeth is generally displayed by humans and other animals as a display of anger, hostility or frustration. It is thought that in humans, clenching the teeth may be an evolutionary instinct to display teeth as weapons, thereby threatening a rival or a predator. The phrase "to grit one's teeth" is the grinding or clenching of the teeth in anger, or to accept a difficult or unpleasant situation and deal with it in a determined way.
In the Bible there are several references to "gnashing of teeth" in both the Old Testament, and the New Testament, where the phrase "weeping and gnashing of teeth" appears no less than 7 times in Matthew alone.
A Chinese proverb has linked bruxism with psychosocial factors. "If a boy clenches, he hates his family for not being prosperous; if a girl clenches, she hates her mother for not being dead."(男孩咬牙，恨家不起；女孩咬牙，恨妈不死。)
In David Lynch's 1977 film Eraserhead, Henry Spencer's partner ("Mary X") is shown tossing and turning in her sleep, and snapping her jaws together violently and noisily, depicting sleep bruxism. In Stephen King's 1988 novel The Tommyknockers, the sister of central character Bobbi Anderson also had bruxism. In the 2000 film Requiem for a Dream, the character of Sara Goldfarb (Ellen Burstyn) begins taking an amphetamine-based diet pill and develops bruxism. In the 2005 film Beowulf & Grendel, a modern reworking of the Anglo-Saxon poem Beowulf, Selma the witch tells Beowulf that the troll's name Grendel means "grinder of teeth", stating that "he has bad dreams", a possible allusion to Grendel traumatically witnessing the death of his father as a child, at the hands of King Hrothgar. The Geats (the warriors who hunt the troll) alternatively translate the name as "grinder of men's bones" to demonize their prey. In George R. R. Martin's A Song of Ice and Fire series, King Stannis Baratheon grinds his teeth regularly, so loudly it can be heard "half a castle away".
In rave culture, recreational use of ecstasy is often reported to cause bruxism. Among people who have taken ecstasy, while dancing it is common to use pacifiers, lollipops or chewing gum in an attempt to reduce the damage to the teeth and to prevent jaw pain. Bruxism is thought to be one of the contributing factors in "meth mouth", a condition potentially associated with long term methamphetamine use.