Early diagnosis of<unk>  is advantageous, but difficult. Early diagnosis can prevent damage that may be incurred and the detrimental effect on quality of life. A diagnosis of<unk>  is usually made clinically, and is mainly based on the person's history (e.g. reports of grinding noises) and the presence of typical signs and symptoms, including tooth mobility, tooth wear, masseteric hypertrophy, indentations on the tongue, hypersensitive teeth (which may be misdiagnosed as reversible pulpitis), pain in the muscles of mastication, and clicking or locking of the temporomandibular joints. Questionnaires can be used to screen for<unk>  in both the clinical and research settings. For tooth grinders who live in same household with other people, diagnosis of grinding is straightforward: Housemates or family members would advise a bruxer of recurrent grinding. Grinders who live alone can likewise resort to a sound-activated tape recorder. To confirm the condition of clenching, on the other hand, bruxers may rely on such devices as the Bruxchecker, Bruxcore, or a beeswax-bearing biteplate. 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.<unk>  is not the only cause of tooth wear. Another possible cause of tooth wear is acid erosion, which may occur in people who drink a lot of acidic liquids such as concentrated fruit juice, or in people who frequently vomit or regurgitate stomach acid, which itself can occur for various reasons. People also demonstrate a normal level of tooth wear, associated with normal function. The presence of tooth wear only indicates that it had occurred at some point in the past, and does not necessarily indicate that the loss of tooth substance is ongoing. People who clench and perform minimal grinding will also not show much tooth wear. Occlusal splints are usually employed as a treatment for<unk> , but they can also be of diagnostic use, e.g. to observe the presence or absence of wear on the splint after a certain period of wearing it at night. The most usual trigger in sleep<unk>  that leads a person to seek medical or dental advice is being informed by sleeping partner of unpleasant grinding noises during sleep. The diagnosis of sleep<unk>  is usually straightforward, and involves the exclusion of dental diseases, temporomandibular disorders, and the rhythmic jaw movements that occur with seizure disorders (e.g. epilepsy). This usually involves a dental examination, and possibly electroencephalography if a seizure disorder is suspected. Polysomnography shows increased masseter and temporalis muscular activity during sleep. Polysomnography may involve electroencephalography, electromyography, electrocardiography, air flow monitoring and audio–video recording. It may be useful to help exclude other sleep disorders; however, due to the expense of the use of a sleep lab, polysomnography is mostly of relevance to research rather than routine clinical diagnosis of<unk> . Tooth wear may be brought to the person's attention during routine dental examination. With awake<unk> , most people will often initially deny clenching and grinding because they are unaware of the habit. Often, the person may re-attend soon after the first visit and report that they have now become aware of such a habit. Several devices have been developed that aim to objectively measure<unk>  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. These are mostly of relevance to research, and are rarely used in the routine clinical diagnosis of<unk> . Examples include the "Bruxcore<unk> -Monitoring Device" (BBMD, "Bruxcore Plate"), the "intra-splint force detector" (ISFD), and electromyographic devices to measure masseter or temporalis muscle activity (e.g. the "BiteStrip", and the "Grindcare"). ICSD-R diagnostic criteria The ICSD-R listed diagnostic criteria for sleep<unk> . The minimal criteria include both of the following: * A. symptom of tooth-grinding or tooth-clenching during sleep, and * B. One or more of the following: * Abnormal tooth wear * Grinding sounds * Discomfort of the jaw muscles With the following criteria supporting the diagnosis: * C. polysomnography shows both: * Activity of jaw muscles during sleep * No associated epileptic activity * D. No other medical or mental disorders (e.g., sleep-related epilepsy, which may cause abnormal movement during sleep). * E. The presence of other sleep disorders (e.g., obstructive sleep apnea syndrome). Definition examples<unk>  is derived from the Greek word (brykein) "to bite, or to gnash, grind the teeth". People who suffer from<unk>  are called<unk> s or bruxers and the verb itself is "to brux". There is no widely accepted definition of<unk> . Examples of definitions include:<unk>  is a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible.<unk>  has two distinct circadian manifestations: it can occur during sleep (indicated as sleep<unk>  or during wakefulness (indicated as awake<unk> ."All forms of<unk>  entail forceful contact between the biting surfaces of the upper and lower teeth. In grinding and tapping this contact involves movement of the mandible and unpleasant sounds which can often awaken sleeping partners and even people asleep in adjacent rooms. Clenching (or clamping), on the other hand, involves inaudible, sustained, forceful tooth contact unaccompanied by mandibular movements."A movement disorder of the masticatory system characterized by teeth-grinding and clenching during sleep as well as wakefulness." "Non-functional contact of the mandibular and maxillary teeth resulting in clenching or tooth grinding due to repetitive, unconscious contraction of the masseter and temporalis muscles." "Parafunctional grinding of teeth or an oral habit consisting of involuntary rhythmic or spasmodic non-functional gnashing, grinding or clenching of teeth in other than chewing movements of the mandible which may lead to occlusal trauma." "Periodic repetitive clenching or rhythmic forceful grinding of the teeth." Classification by temporal pattern + Comparison of typical features of sleep<unk>  and awake<unk> . Sleep<unk>  Awake<unk>  Occurrence While asleep, mostly during periods of sleep arousal While awake Time–intensity relationship Pain worst on waking, then slowly gets better Pain worsens throughout the day, may not be present on waking Noises Commonly associated Rarely associated Activity Clenching and grinding Usually clenching, occasionally clenching and grinding Relationship with stress Unclear, little evidence of a relationship Stronger evidence for a relationship, but not conclusive Prevalence (general population) 9.7–15.9% 22.1–31% Gender distribution Equal gender distribution Mostly females Heritability Some evidence Unclear<unk>  can be subdivided into two types based upon when the parafunctional activity occurs – during sleep ("sleep<unk> "), or while awake ("awake<unk> "). This is the most widely used classification since sleep<unk>  generally has different causes to awake<unk> , although the effects on the condition on the teeth may be the same. The treatment is also often dependent upon whether the<unk>  happens during sleep or while awake, e.g., an occlusal splint worn during sleep in a person who only bruxes when awake will probably have no benefit. Some have even suggested that sleep<unk>  is an entirely different disorder and is not associated with awake<unk> . Awake<unk>  is sometimes abbreviated to AB, and is also termed "diurnal<unk> ", DB, or "daytime bruxing". Sleep<unk>  is sometimes abbreviated to SB, and is also termed "sleep-related<unk> ", "nocturnal<unk> ", or "nocturnal tooth grinding". According to the International Classification of Sleep Disorders revised edition (ICSD-R), the term "sleep<unk> " is the most appropriate since this type occurs during sleep specifically rather than being associated with a particular time of day, i.e., if a person with sleep<unk>  were to sleep during the day and stay awake at night then the condition would not occur during the night but during the day. The ICDS-R defined sleep<unk>  as "a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep", classifying it as a parasomnia. The second edition (ICSD-2) however reclassified<unk>  to a "sleep related movement disorder" rather than a parasomnia. Classification by cause Alternatively,<unk>  can be divided into primary<unk>  (also termed "idiopathic<unk> "), where the disorder is not related to any other medical condition, or secondary<unk> , where the disorder is associated with other medical conditions. Secondary<unk>  includes iatrogenic causes, such as the side effect of prescribed medications. Another source divides the causes of<unk>  into three groups, namely central or pathophysiological factors, psychosocial factors and peripheral factors. The World Health Organization's International Classification of Diseases 10th revision does not have an entry called<unk> , instead listing "tooth grinding" under somatoform disorders. To describe<unk>  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<unk> , 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, tempormandibular disorders and other physical injuries, and severe psychosocial impairment. Classification by duration The ICSD-R also described three
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