be continued until there is only a normal level of sensitivity from the teeth, although it should be remembered that sensitivity to thermal stimuli is also a symptom of pulpitis, and may indicate the presence of tooth decay rather than merely hypersensitive teeth. splints may also reduce muscle strain by allowing the upper and lower jaw to move easily with respect to each other. treatment goals include: constraining the bruxing pattern to avoid damage to the temporomandibular joints; stabilizing the occlusion by minimizing gradual changes to the positions of the teeth, preventing tooth damage and revealing the extent and patterns of bruxism through examination of the markings on the splint's surface. a dental guard is typically worn during every night's sleep on a long-term basis. however, a meta-analysis of occlusal splints (dental guards) used for this purpose concluded "there is not enough evidence to state that the occlusal splint is effective for treating sleep 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. a 2020 overview of systematic reviews found that botulinum toxin type a (btx-a) showed a significant pain and sleep bruxism frequency reduction when compared to placebo or conventional treatment (behavioral therapy, occlusal splints, and drugs), after 6 and 12 months. 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. "large scale, double-blind, experiment confirming the effectiveness of this approach have yet to be carried out." occlusal adjustment/reorganization as an alternative to simply reactively repairing the damage to teeth and conforming to the existing occlusal scheme, occasionally some dentists will attempt to reorganize the occlusion in the belief that this may redistribute the forces and reduce the amount of damage inflicted on the dentition. sometimes termed "occlusal rehabilitation" or "occlusal equilibration", this can be a complex procedure, and there is much disagreement between proponents of these techniques on most of the aspects involved, including the indications and the goals. it may involve orthodontics, restorative dentistry or even orthognathic surgery. some have criticized these occlusal reorganizations as having no evidence base, and irreversibly damaging the dentition on top of the damage already caused by bruxism. history two thousand years ago, shuowen jiezi by xu shen documented the definition of chinese character "齘" (bruxism) as "the clenching of teeth" (齒相切也). 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. in 1931, frohman first coined the term bruxism. occasionally recent medical publications will use the word bruxomania with bruxism, to denote specifically bruxism that occurs while awake; however, this term can be considered historical and the modern equivalent would be awake bruxism or diurnal bruxism. it has been shown that the type of research into bruxism has changed over time. overall between 1966 and 2007, most of the research published was focused on occlusal adjustments and oral splints. behavioral approaches in research declined from over 60% of publications in the period 1966–86 to about 10% in the period 1997–2007. in the 1960s, a periodontist named sigurd peder ramfjord championed the theory that occlusal factors were responsible for bruxism. 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.