Bruxism is characterized by the grinding of the teeth and typically includes the clenching of the jaw. It is an oral
parafunctional activityA para-functional habit or parafunctional habit is the habitual exercise of a body part in a way that is other than the most common use of that body part. The term is most commonly used by dentists, orthodontists, or maxillofacial specialists to refer to parafunctional uses of the mouth, tongue...
that occurs in most humans at some time in their lives. In most people, bruxism is mild enough not to be a health problem. While bruxism may be a diurnal or nocturnal activity, it is bruxism during sleep that causes the majority of health issues and can even occur during short naps. Bruxism is one of the most common sleep disorders.
Causes
Bruxism is a
habitHabits are routines of behavior that are repeated regularly and tend to occur subconsciously. Habitual behavior often goes unnoticed in persons exhibiting it, because a person does not need to engage in self-analysis when undertaking routine tasks...
rather than a
reflexA reflex action, also known as a reflex, is an involuntary and nearly instantaneous movement in response to a stimulus. A true reflex is a behavior which is mediated via the reflex arc; this does not apply to casual uses of the term 'reflex'.-See also:...
chewing activity. Reflex activities happen reliably in response to a stimulus, without involvement of subconscious brain activity.
ChewingMastication or chewing is the process by which food is crushed and ground by teeth. It is the first step of digestion and it increases the surface area of foods to allow more efficient break down by enzymes. During the mastication process, the food is positioned between the teeth for grinding by...
and clenching are complex neuromuscular activities that can be controlled either by subconscious processes or by conscious processes within the brain. During sleep, (and for some during waking hours while conscious attention is distracted) subconscious processes can run unchecked, allowing bruxism to occur.
Some bruxism activity is rhythmic with bite force pulses of tenths of a second (like chewing), and some has a longer bite force pulses of 1 to 30 seconds (clenching). Researchers classify bruxism as "a habitual behavior, and a sleep disorder."
The
etiologyEtiology is the study of causation, or origination. The word is derived from the Greek , aitiologia, "giving a reason for" ....
of problematic bruxism can be quite varied, from allergic reactions or medical ailments, to trauma (such as a car crash) to a period of unusual stress, but once bruxism becomes a habit, the original stimulus can be removed without ending the habit. Certain medical conditions can trigger bruxism, including digestive ailments and
anxietyAnxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
.
Signs
Most people are not aware of their bruxism. Only an estimated 5% go on to develop symptoms, such as jaw pain and headaches, which prompt treatment. A sleeping partner or parent may notice the behavior first, although sufferers may notice pain symptoms without understanding the cause.
Bruxism can result in
occlusal traumaOcclusal trauma is a dental term that refers to the damage incurred when teeth are left in traumatic occlusion without proper treatment.When the maxillary and mandibular dental arches approach each together, as they do, for example, during chewing or at rest, the relationship between the opposing...
, the abnormal wear patterns of the
occlusalThere are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
surface,
abfractionAbfraction is the loss of tooth structure from flexural forces. It is hypothesized that enamel, especially at the cementoenamel junction , undergo this pattern of destruction by separating the enamel rods....
s and fractures in the teeth. Over time, dental damage increases. Bruxism is the leading cause of occlusal trauma and a significant cause of
tooth lossTooth loss is when one or more teeth come loose and fall out. Tooth loss is normal for deciduous teeth , when they are replaced by a person's adult teeth. Otherwise, losing teeth is undesirable and is the result of injury or disease, such as mouth trauma, tooth injury, tooth decay, and gum disease...
and gum recession. Bruxism can be loud enough to wake a sleeping partner. Some individuals clench without significant lateral movements.
In a typical case involving lateral motion, the
caninesIn mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...
and
incisorIncisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s of the opposing arches are moved against each other laterally, i.e., with a side-to-side action, by the
medial pterygoid muscleThe medial pterygoid , is a thick, quadrilateral muscle of mastication.The mandibular branch of the fifth cranial nerve, the trigeminal nerve, innervates the medial pterygoid muscle.-Origin and insertion:...
s that lie medial to the temporomandibular joints bilaterally. This movement abrades tooth structure and can lead to the wearing down of the
incisalThere are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
edges of the teeth. People with bruxism may also grind their
posteriorThere are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
teeth, which will wear down the
cuspA cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
s of the occlusal surface. Most (but not all) bruxism includes clenching force provided by masseter and temporalis muscle groups, but some bruxers clench and grind front teeth only, which involves neither masseter nor temporalis muscle groups. Teeth hollowed by previous decay (
cariesCaries is a progressive destruction of any kind of bone structure, including the skull, ribs and other bones, or the teeth. Caries can be caused by osteomyelitis, which is a microorganism disease. A disease that involves caries is mastoiditis, an inflammation of the mastoid process, in which the...
), or dental drilling, may collapse from bruxism's cyclic pressures.
Symptoms
Patients may present with a variety of
symptomA symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s, including:
- Anxiety, stress, and tension
- Depression
- Earache
- Eating disorders
- Headaches
- Migraines
- Loose teeth
- Tinnitus
- Gum recession
- Neck pain
- Insomnia
- Sore or painful jaw
Sequelae
Eventually, bruxism with lateral movements shortens and blunts the teeth being ground and may lead to myofascial muscle pain, temporomandibular joint dysfunction and
headacheA headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
s. If enough
enamelTooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
has been abraded, the softer
dentinDentine is a calcified tissue of the body, and along with enamel, cementum, and pulp is one of the four major components of teeth. Usually, it is covered by enamel on the crown and cementum on the root and surrounds the entire pulp...
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. In severe, chronic cases, bruxism can lead to
arthritisArthritis is a form of joint disorder that involves inflammation of one or more joints....
of the
temporomandibular jointThe temporomandibular joint is the joint of the jaw and is frequently referred to as TMJ. There are two TMJs, one on either side, working in unison. The name is derived from the two bones which form the joint: the upper temporal bone which is part of the cranium , and the lower jaw bone called the...
s. The jaw clenching that is often part of bruxism can be an unconscious neuromuscular daytime activity, which should be treated as well, usually through physical therapy (recognition and stress response reduction).
Diagnosis
Bruxism is not the only cause of tooth wear, making it difficult to diagnose by visual evidence alone. Abraded teeth are usually brought to the patient's attention during a routine dental examination.
The most reliable diagnostic technique is measuring EMG (
electromyographyElectromyography is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle...
). These measurements pick up electrical signals from the chewing muscles (masseter and temporalis). This method is commonly used in sleep labs. Three forms of EMG measurement are available outside of sleep labs.
"Bedside" EMG units are similar to those used by sleep labs. These units pick up their signals from facial muscles through wires connecting the bedside unit to electrodes that are adhesively attached to the user's face. TENS electrodes or ECG electrodes may be used.
A
biofeedback headbandA biofeedback headband is a self-contained biofeedback unit which is worn on the head and held in place by an elastic strap. Biofeedback headbands are most often used for controlling bruxism during sleep, but can also be used during the day...
may be used in silent mode to record the total number of clenching incidents and the total clenching time each night. These two numbers easily distinguish clenching from rhythmic grinding and allow dentists to quantify severity levels. Biofeedback headbands do not require adhesive electrodes or wires attached to the face. They do not record the exact time, duration, and strength of each clenching incident as bedside EMG monitors do.
Bedside EMG units and
biofeedback headbandsA biofeedback headband is a self-contained biofeedback unit which is worn on the head and held in place by an elastic strap. Biofeedback headbands are most often used for controlling bruxism during sleep, but can also be used during the day...
can both be used either as a diagnosis measurement or in biofeedback mode as a treatment to help patients break their bruxism habit.
"Disposable" EMG monitors adhesively mount to the side of the face over the masseter muscle. They monitor one night and provide a single-digit measure of bruxism severity.
Associated factors
The following factors may be associated with bruxism (whether by cause or effect):
- Disturbed sleep patterns and other sleep disorder
A sleep disorder, or somnipathy, is a medical disorder of the sleep patterns of a person or animal. Some sleep disorders are serious enough to interfere with normal physical, mental and emotional functioning...
s (obstructive sleep apneaObstructive sleep apnea or obstructive sleep apnea syndrome is the most common type of sleep apnea and is caused by obstruction of the upper airway. It is characterized by repetitive pauses in breathing during sleep, despite the effort to breathe, and is usually associated with a reduction in...
, hypopnea, snoringSnoring is the vibration of respiratory structures and the resulting sound, due to obstructed air movement during breathing while sleeping. In some cases the sound may be soft, but in other cases, it can be loud and unpleasant...
, moderate daytime sleepinessSomnolence is a state of near-sleep, a strong desire for sleep, or sleeping for unusually long periods . It has two distinct meanings, referring both to the usual state preceding falling asleep, and the chronic condition referring to being in that state independent of a circadian rhythm...
)
- Malocclusion
A malocclusion is a misalignment of teeth or incorrect relation between the teeth of the two dental arches. The term was coined by Edward Angle, the "father of modern orthodontics", as a derivative of occlusion, which refers to the manner in which opposing teeth meet.-Presentation:Most people have...
, in which the upper and lower teeth occlude in a disharmonic way, e.g., through premature contact of back teeth
- Relatively high levels of consumption of caffeinated drinks and foods, such as coffee, colas, and chocolate
- High levels of blood alcohol
- Smoking
- High levels of anxiety
Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
, stressStress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
, work-related stress, irregular work shifts, stressful profession and ineffective coping strategiesCoping Strategies is treatment designed for posttraumatic stress disorder within United States Armed Forces personnel and their families by the charitable organization Patriot Outreach...
- Drug use, such as SSRIs and stimulants, including methylenedioxymethamphetamine
MDMA is an entactogenic drug of the phenethylamine and amphetamine class of drugs. In popular culture, MDMA has become widely known as "ecstasy" , usually referring to its street pill form, although this term may also include the presence of possible adulterants...
(ecstasy), methylenedioxyamphetamine (MDA), methylphenidateMethylphenidate is a psychostimulant drug approved for treatment of attention-deficit hyperactivity disorder, postural orthostatic tachycardia syndrome and narcolepsy. It may also be prescribed for off-label use in treatment-resistant cases of lethargy, depression, neural insult and obesity...
and other amphetamines, including those taken for medical reasons Frequent use of GHBγ-Hydroxybutyric acid , also known as 4-hydroxybutanoic acid and sodium oxybate when used for medicinal purposes, is a naturally occurring substance found in the central nervous system, wine, beef, small citrus fruits, and almost all animals in small amounts. It is also categorized as an illegal...
and similar GABAγ-Aminobutyric acid is the chief inhibitory neurotransmitter in the mammalian central nervous system. It plays a role in regulating neuronal excitability throughout the nervous system...
-inducing analogues such as Phenibutβ-Phenyl-γ-aminobutyric acid, better known as phenibut or less commonly fenibut or phenybut, is a derivative of the naturally occurring inhibitory neurotransmitter γ-aminobutyric acid . The addition of a phenyl ring allows phenibut to cross the blood brain barrier...
- Hypersensitivity of the dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
receptors in the brain
- Disorders such as Huntington's
Huntington's disease, chorea, or disorder , is a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and dementia. It typically becomes noticeable in middle age. HD is the most common genetic cause of abnormal involuntary writhing movements called chorea...
and Parkinson's diseaseParkinson's disease is a degenerative disorder of the central nervous system...
s
- Obsessive–compulsive disorder
Treatment
If diagnosed early, finding and eliminating the original cause(s) may cure bruxism. Later on, habitual bruxism can be treated by habit-modification.
Treating associated factors can reduce or eliminate the behavior in cases where bruxism has not become habitual.
Dental guards and splints
A
dental guardA mouthguard is a protective device for the mouth that covers the teeth and gums to prevent and reduce injury to the teeth, arches, lips and gums...
or splint can reduce tooth abrasion. Dental guards are typically made of plastic and fit over some or all of upper and/or lower teeth. The guard protects the teeth from abrasion and can 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. Dental guards do not cure the condition.
A
repositioning splint is designed to change the patient's occlusion, or bite.
Another option is an NTI-tss (nociceptive trigeminal inhibitor) dental guard.
NociceptorA nociceptor is a sensory receptor that responds to potentially damaging stimuli by sending nerve signals to the spinal cord and brain. This process, called nociception, usually causes the perception of pain.-History:...
nerves sense and respond to pressure. The trigeminal nerve supplies the face and mouth. The NTI appliance snaps onto the front teeth. Normally when the mouth is closed, the upper and lower front teeth overlap: The NTI prevents this overlap and translates 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. Unfortunately, for patients who do not subconsciously clench less using an NTI devce, the NTI can lead to more severe damage from clenching. The NTI device must be fitted by a 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. Randomly controlled trials with these type devices generally show no benefit over other therapies. Clenching hard while wearing an NTI device may cause worse damage, because the NTI changes the forces on the teeth and the tempormandibular joint. NTI patients require ongoing monitoring by a dentist.
While there is some debate on this approach, the use of mouthguards can protect the skull from ongoing deterioration and damage. Some studies have found inter sutural bleeding occurs while grinding at night. The mouthguard may not entirely prevent the clenching or grinding motion but it can lessen the impact the TMJ impact has on the rest of the skull. Craniosacral therapy is said to both alleviate these inter sutural imbalances as well as alleviate the internal stress which is at the source of the grinding.
Contingent electric stimulation
A device monitors the electromyographic (EMG) activity of the temporalis muscle. When the muscle contracts, the device records the muscle activity and sends out a contingent electrical stimulation (CES) to receptors in the skin. The contingent electrical stimulation is designed to trigger an inhibitory reflex in the brain stem that relaxes the jaw-muscles and inhibits the bruxing event without waking up the user. The function of the device is therefore different from other devices in the market, which wake up the user acoustically to stop the grinding.
The device has an electrode with three metal
contact padContact pads are designated surface areas of a printed circuit board or die of an integrated circuit. Possibilities to contact to pads include soldering, wirebonding, Flip chip mounting, or probe needles....
s to record the muscle activity and send out the CES. The electrode is attached to the skin with a disposable gel-pad.
The level of stimulation is set by the user at the same time as the calibration, that must be done by the user in order for the bruxing events to be detected correctly. The stimulation intensity is clearly perceived by the user -but not painful. All user interaction with the device is done via a menu on the display of the device.
The device is intended for use during sleep – although it may also be used while the user is awake. The device reportedly reduces grinding, usually without interfering with sleep.
Biofeedback
Various
biofeedbackBiofeedback is the process of becoming aware of various physiological functions using instruments that provide information on the activity of those same systems, with a goal of being able to manipulate them at will...
devices are currently available, and effectiveness varies significantly depending on whether the biofeedback is used only during waking hours, or during sleep as well. Many authorities remain unconvinced of the efficacy of daytime-only biofeedback. The efficacy of nighttime biofeedback can depend strongly on daytime training, which is used to establish a Pavlovian response to the biofeedback signal that persists during sleep.
The first wearable nighttime bruxism biofeedback device (a
biofeedback headbandA biofeedback headband is a self-contained biofeedback unit which is worn on the head and held in place by an elastic strap. Biofeedback headbands are most often used for controlling bruxism during sleep, but can also be used during the day...
) was introduced in 2001. A
biofeedback headbandA biofeedback headband is a self-contained biofeedback unit which is worn on the head and held in place by an elastic strap. Biofeedback headbands are most often used for controlling bruxism during sleep, but can also be used during the day...
is a battery-powered device that sounds a tone when it senses EMG muscle activity in the temporalis muscles. The tone starts off at a low volume and gets louder until the clenching incident stops, or until a maximum volume level is reached. The intent is to allow people to stop clenching without awakening. The
biofeedback headbandA biofeedback headband is a self-contained biofeedback unit which is worn on the head and held in place by an elastic strap. Biofeedback headbands are most often used for controlling bruxism during sleep, but can also be used during the day...
also tallies nightly data on the number of events that last for at least two seconds and the total accumulated duration of those events. A "fast-response" headband catches events that last for as little as 0.2 seconds. The volume of the biofeedback tone and the bite force required to trigger the device are adjustable. Clinical trials have shown that after three brief sessions of Pavlovian response conditioning and subsequent use of a biofeedback headband during sleep, more than 75% of bruxism sufferers experience more than a 60% reduction in nighttime clenching from the first day of biofeedback onward, and more than 50% of bruxism sufferers experience more than an 80% reduction in bruxism within the first month.
Another therapy relies on stimulating the taste buds. The therapy involves suspending sealed packets containing a harmless but bad-tasting substance (e.g. hot sauce,
vinegarVinegar is a liquid substance consisting mainly of acetic acid and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. Commercial vinegar is produced either by fast or slow fermentation processes. Slow methods generally are used with traditional...
, denatonium benzoate, etc.) between the rear molars using an orthodontic-style appliance. Attempts to bring the teeth together ruptures the packets, alerting the user. The Taste-Based Approach claims to suffer less from desensitization over time than sound-based biofeedback approaches, but may interrupt sleep more.
Another device (patented in 2005) forces the patient to switch from breathing through the nose to breathing through the mouth.The device responds to muscle activity by signaling a mechanical actuator that slowly reduces airflow (without closing them) to the nostrils to force breathing to occur through the mouth. Once the patient stops clenching, the flaps open.
Botox
Botulinum toxinBotulinum toxin is a protein produced by the bacterium Clostridium botulinum, and is considered the most powerful neurotoxin ever discovered. Botulinum toxin causes Botulism poisoning, a serious and life-threatening illness in humans and animals...
(Botox) can lessen bruxism's effects. An extremely dilute form of Botox is injected to weaken (partially paralyze) muscles and has been used extensively in cosmetic procedures to 'relax' the muscles of the face.
Botox was originally developed for use in treating
strabismusStrabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
(misalignment of eyes), during trials of which its effects on wrinkles in the eye area were discovered. It was, and continues to be, used to treat diseases of muscle spasticity such as
strabismusStrabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely...
,
blepharospasmA blepharospasm , is any abnormal contraction or twitch of the eyelid....
(eyelid spasm), and
torticollisTorticollis, or wryneck, is a stiff neck associated with muscle spasm, classically causing lateral flexion contracture of the cervical spine musculature...
(wry neck). Bruxism can also be regarded as a disorder of repetitive, unconscious contraction of the
masseter muscleIn human anatomy, the masseter is one of the muscles of mastication.In the animal kingdom, it is particularly powerful in herbivores to facilitate chewing of plant matter.-Origin and insertion of the two heads:...
(the large muscle that moves the jaw). In the treatment of bruxism, Botox weakens the muscle enough to reduce the effects of grinding and clenching, but not so much as to prevent proper use of the muscle. Botox treatment typically involves five or six injections into the masseter muscles. It takes a few minutes per side, and the patient starts feeling the effects the next day. Occasionally, bruising can occur, but this is quite rare. Injections must be repeated more than once per year.
The optimal dose of Botox must be determined for each person as some people have stronger muscles that need more Botox. This is done over a few touch-up visits with the physician. The effects last for about three months. The muscles do
atrophyAtrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...
, however, so after a few rounds of treatment, it is usually possible either to decrease the dose or increase the interval between treatments.
Dietary supplements
There is anecdotal evidence that suggests taking certain combinations of dietary supplements may alleviate bruxism;
pantothenic acidPantothenic acid, also called pantothenate or vitamin B5 , is a water-soluble vitamin. For many animals, pantothenic acid is an essential nutrient. Animals require pantothenic acid to synthesize coenzyme-A , as well as to synthesize and metabolize proteins, carbohydrates, and fats.Pantothenic acid...
,
magnesiumMagnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
, and
calciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
are mentioned on dietary supplement websites. Calcium is known to be a treatment for gastric problems, and gastric problems such as acid reflux are known to increase bruxism..
Repairing damage
Damaged teeth can be repaired by replacing the worn natural crown of the tooth with prosthetic
crownA crown is a type of dental restoration which completely caps or encircles a tooth or dental implant. Crowns are often needed when a large cavity threatens the ongoing health of a tooth. They are typically bonded to the tooth using a dental cement. Crowns can be made from many materials, which...
s. 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
occlusalOcclusion, in a dental context, means simply the contact between teeth. More technically, it is the relationship between the maxillary and mandibular teeth when they approach each other, as occurs during chewing or at rest....
guard should be fabricated to wear during sleep.
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