Sleep-Related Bruxism


Have you been told that you are a tooth grinder? It is more common than you might think. Dentists have, for generations, prescribed night guards to protect the teeth from this condition, with very little scientific evidence and even less training. There are hard ones, and soft ones, some that fit on the upper teeth and some that fit on the lower. Each dentist has their own preference but do they actually treat the condition or only offer protection from the grinding and clenching?

Dental schools place a very low priority on training dentists in this field. Many dentists do not treat it as they are frustrated with broken appliances and patients returning for adjustment after adjustment. So they simply ignore the problem affecting 15% of their patients and perform treatments on their patients that are contraindicated in the presence of sleep-related bruxism.

The latest research has found upper and lower night guards to be completely ineffective in treating sleep-related bruxism and can make it worse. This can be seen when examining a night guard after a few weeks. There are signs of scuff marks across the biting surface or cracks appearing in the material. This is due to the sleep-related bruxism persisting despite the use of the night guard. As well, studies have also shown that upper bruxism appliances can increase the risk of sleep apnea by increasing a specific score called the AHI (Apnea Hypopnea Index) by allowing the tongue to fall back into the throat region.

Even today, few, if any dental schools teach about sleep-related bruxism and, if you search the web for sleep-related bruxism, most of the sites simply refer to bruxism, without differentiating if it occurred during awake periods or sleep.

Read on for the most up-to-date information on sleep-related bruxism.

What is sleep-related bruxism and why is it important to treat it?

During sleep, it is common for the lower jaw to move around. This is termed Rhythmic Masticatory Muscle Activity or RMMA. This consists of two forms of muscle activity: a series of repetitive contractions (grinding) or sustained contractions of jaw clenching. These muscle contractions, when extreme, produce tooth grinding sounds during sleep and are referred to as sleep-related bruxism. The patient is usually unaware that they are doing this as it occurs once they are asleep. It is often their bed partner that alerts them to this, as it disturbs their sleep.

The two most commonly reported symptoms are sensitivity of the teeth to cold, and headaches, often in the temple region.

Individuals 25-35 experience the worst headaches whereas individuals 40+ experience more dental damage, bone changes, TMJ problems, and cardiovascular complications. All ages experience tooth sensitivity.

Sleep-related bruxism produces forces much greater than when chewing hard or chewy foods, the muscles contract with 100% of their force potential. With each sleep-related bruxism event, there is a predictable series of events that occurs including:

  1.  an increase in EEG (brain electrical) resulting in disturbed sleep
  2. the masseter and temporalis chewing muscles contract with maximum force
  3. the posterior digastric muscle (jaw opener) contracts with maximum force (an attempt to open the jaws)
  4. The stomach is stimulated and acid production increases triggering acid reflux (GERD)
  5. The sucking reflex occurs and cheek biting can result (over time formation of linea alba)
  6. The swallowing reflex is often activated

This sequence of events occurs with ever sleep-related bruxism event and can occur hundreds of times each night.

How are Awake and  Sleep-Related Bruxism Classified?

World Health Organization (WHO) publishes a classification with coding for medical insurers called ICD (international classification of diseases). Their latest publication, from December 2018, is version 11. They have extended their classification of sleep-related bruxism to include severity levels.

Sleep-related bruxism and awake bruxism are very different diseases.  They are classified differently, they have different causes, and they are treated very differently. Awake bruxism falls under dentofacial abnormalities whereas sleep-related bruxism falls under sleep-wake disorders. Awake bruxism is stress and personalty related whereas sleep-related bruxism is neurological. They cannot be thought of as the same condition nor can they be treated the same.

Sleep-Related Bruxism in More Detail

Rhythmic movements such as chewing and bruxing are controlled by central pattern generators (CPG) is involved within the brain. Mastication (and sleep-related bruxism) are driven by the hypoglossal nucleus, which is controlled by the dorsal medullary reticular column (DMRC) and the nucleus of the tractus solitaries (NTS).

It has been recently found that patients suffering from sleep-related bruxism have a genetic mutation of the gene HTR2A rs2770304, which is responsible for creating the 2A receptor for serotonin (a neurotransmitter in the brain and gut). Normally, this gene acts to turn off activity and to maintain the normal function of the nervous system.

As a result of this mutation in sleep-related bruxism, this gene occurs in multiple copies (polymorphism) resulting in too many 2A serotonin receptors in the brain. The 2A receptor suppresses nerve activity when stimulated resulting in suppression of the brain regions involved with certain cranial reflexes. This results in an imbalance in function and over-suppression of the nervous system.

The result of this imbalance is that protective reflexes of the jaw such as the masseter inhibitory reflex are suppressed, allowing the jaw muscles to contract with 100% of their bite force during sleep-related bruxism episodes. This results in a loss of natural protection for the teeth and supporting structures See our video page for informative videos on these topics)

Central pattern generators are nerve loops in the brain that produce cyclic regular outputs of firing that help control reflex activities such as walking, chewing, swallowing, and breathing.

In sleep-related bruxism, the central pattern generators that control chewing are activated abnormally and the muscles begin contracting. Due to the inhibition of the masseter inhibitory reflex, this is not normal chewing but rather chewing and clenching with 100% of the bite force.

Because of the mutation of the  HTR2A rs2770304 gene, sleep-related bruxism cannot be cured at this time, only controlled. It should also be noted that in some people, the excess genes are inactive only to be activated later in life by a trauma, medication, or concurrent sleep disorder such as sleep apnea. As well, the number of excess HTR2A genes is not the same for everyone and the more one has, the worse the condition will be.

There is another aspect of sleep-related bruxism we should discuss as it is by far the most serious.

Sleep-related bruxism affects the most powerful cranial reflex known: the trigeminal cardiac reflex.

The Trigeminal Cardiac Reflex

The trigeminal cardiac reflex (TCR) is one of the most powerful cranial reflexes, directly affecting  the autonomic (automatic) nervous system. The TCR (abbreviation for this reflex)  occurs with stimulation along the trigeminal nerve, or cranial nerve five (V). The trigeminal nerve has three major branches: the ophthalmic, the maxillary and the mandibular branches, and the TCR may be stimulated along all three.

The ophthalmic nerve supplies the nerves around and behind the eyes, as well as the forehead region and subdural membranes of the brain. When it is stimulated by trauma or surgical procedures, the TCR may be activated.

The maxillary branch affects the upper teeth and upper jaw, throat muscles and inner ear. The upper 1st bicuspids and upper eye teeth are connected to this reflex.

The mandibular branch affects all of the lower teeth, jaw muscles, and TMJ or jaw joints.

All three branches of the Trigeminal or nerve converge or meet in midbrain in the Trigeminal or Gasserion ganglion.

It is at the Gasserion or trigeminal ganglion, where sleep-related bruxism stimulates TCR.

The classical reaction of the TCR, when stimulated, is a rapid drop in blood pressure, heart rate, breathing, and an increase in gastric flow or stomach acids. During surgery on the face, this reflex can accidentally be stimulated resulting in a serious and sometimes fatal drop.

Sleep-related bruxism is unique in that the TCR stimulation occurs at the Gasserion ganglion. Stimulation in this region has the opposite effect increasing heart rate, blood pressure, and breathing.

Recent studies have shown that the increase in heart rate and blood pressure seen in sleep-related bruxism is also a significant risk factor for cardiovascular disease.

Those who suffer from sleep-related bruxism demonstrate an interesting finding: when they lightly touch their incisors together (as in biting a piece of thread), the lower jaw will begin to shake or tremor. This finding is a positive sign of active sleep-related bruxism. For more detailed information on the Trigeminal Cardiac Reflex, please click here.

The forces generated by sleep-related bruxism are much greater than when awake:

  • Chewing meat = 25 psi (pounds per square inch pressure)
  • Biting a hard carrot = 28 psi
  • Biting as hard as you can when awake = ~30 psi
  • Sleep-related bruxism  100-120 psi in men and 70-90 psi in women!

This is due to a protective reflex of the jaw muscles, the masseter inhibition reflex (MIR) being suppressed by sleep bruxism. The MIR normally restricts how hard the masseter muscle contracts, limiting it to safe levels. During sleep-related bruxism, this reflex is effectively inactivated and the masseter contracts with 100% of its force.

The Luco Hybrid device reactivates the masseter inhibitory reflex and virtually stops the sleep-related bruxism events from occurring. This is much different from classical night guards that only “protect the teeth” from the forces while allowing them to occur along with TCR activation. This effect also reduces the cardiovascular risk of sleep-related bruxism.

The following screenshot of a sleep study of a sleep bruxism patient demonstrates the elimination of sleep bruxism events, stabilization of the patient’s respiration, and stabilization of the heart rate (which was being affected by the sleep bruxism) when the same patient was wearing a Luco Hybrid device.

As you can see, the forces generated during sleep bruxism are substantial and can potentially cause very serious damage. Left untreated, this condition can cause progressive irreversible damage to the teeth, surrounding bone, jaw bones, musculature, and TMJ. Sleep-related bruxism is a significant cause of TMJ problems due to the considerable pressure placed on the TMJ during sleep bruxism events (it only takes about 15 psi to cause damage to the TMJ). With acid reflux, the enamel can be softened, increasing significantly the wear to the enamel.

Sleep-related bruxism can be in its primary form (occurring independently) or in secondary forms to other diseases or medications. To date, it is known that sleep apnea and secondary sleep-related bruxism can occur, with the sleep-related bruxism synchronized between the apnea events. It is felt that this may stimulate breathing by waking the patient into shallower sleep. There are a number of groups of medication that can initiate sleep-related bruxism in a asymptomatic patient susceptible to it. Once sleep-related bruxism has been activated, even if the causative medication is discontinued, more than 50% of these patients will experience sleep-related bruxism for life. These medications include SSRI and SSRNI type antidepressants, stimulants such as Ritalin, and more. It is advisable to ask your pharmacist whether a prescription can trigger or worsen sleep-related bruxism before taking it.

Sleep-related bruxism has three different presentations in a sleep study:

  • Tonic or clenching type
  • Phasic or grinding type
  • Mixed or a combination of both types

Sleep-related bruxism is usually diagnosed by either the patient (with changes to their teeth or jaws or pain symptoms), the dentist (with clinical signs such as premature failure of fillings, abfraction lesions, etc.), or by a sleep specialist during a sleep study. Most sleep-related bruxism goes undetected.

It has been proposed for a sub-classified into three subtypes:

  1. Possible: patient-reported symptoms without clinical signs
  2. Probable: patient-reported symptoms with clinical signs
  3. Definite: patient-reported symptoms, clinical signs, and an overnight sleep study with muscle recording (supported by a microphone or video recording).

Dental radiographs can identify the effects on the jaws from sleep bruxism. The following image shows a panorex (orthopantomogram) displaying some of the effects of sleep-related bruxism. The first demonstrates calcified stylomandibular ligaments (ligaments that restrict the range of motion of the lower jaw to normal movements) and antigonial notching or a bend in the lower jaw caused by tonic sleep bruxism (clenching type) involving the masseter and medial pterygoid muscles. The lower border of the mandible should be straight and not bent as seen. The ligaments are soft tissue and should not show on a radiograph. This is termed Eagle’s Syndrome. They should not be seen on a radiograph, but in sleep-related bruxism, they may calcify or harden (showing on radiographs).

The second panorex demonstrates coronoid elongation or stretching of the coronoid process (attachment of the temporalis muscle) caused by tonic sleep-related bruxism involving the temporalis muscles. The orange dotted line marks the highest point of the coronoid process. In a normal individual, this line should pass through the yellow dots on the condyles (balls) of the TMJ.

SRB does not require a sleep study for diagnosis and treatment, a dentist can diagnose this and treat it in their office from the signs and symptoms observed. If the dentist suspects a concurrent sleep disorder, such as sleep apnea, they are obliged to refer the patient for an overnight supervised sleep study at a sleep laboratory, to ensure all the sleep problems are being addressed.  There are medical conditions that have bruxism as a symptom ( such as faciomandibular myoclonus, SRBD, RBD, abnormal swallowing, gastroesophageal reflux (GERD), night terrors, confusional arousals, dyskinetic jaw movements persisting in sleep (dystonia, tremor, chorea, dyskinesia), and, rarely,  in sleep-related epilepsy). Some medications can initiate or worsen existing sleep-related bruxism by increasing levels of serotonin in the brain. If the dentist is unsure, a home sleep study is always the best course of action.

Sleep studies can accurately record sleep-related bruxism if equipped to record this (with an EMG module to record muscle activity). The following tracings are actual patient recordings using a 12-channel Type 3 sleep monitor (Medibyte Event) with electromyographic (EMG) muscle recording module. The first is a tracing of normal sleep and the second demonstrates numerous sleep-related bruxism bursts (click to enlarge).

In the second tracing above, the amplitude or amount of force being generated is in the range of 10-14 x the normal maximum bite when awake. These bruxism events or bursts can occur hundreds of times per night, disturbing the patient’s sleep. The Epworth Sleepiness Scale is used to screen patients for excessive sleepiness. With OSA it is >10. With sleep-related bruxism patients score in the 6-9 range for sleepiness qualifying it as a true sleep disorder and quantifying the disturbed sleep associated with sleep-related bruxism.

Sleep-related bruxism can be destructive to the teeth, the supporting bone and gum tissues, the TMJ complex including the neck, and the musculature. The effects often result in hypersensitivity of the teeth to temperatures, headaches (particularly in the temple region upon waking), repeated damage to the teeth, and sleep disruption. Sleep-related bruxism can jam cranial sutures affecting normal CSF flow (from the ventricles of the brain through the spinal cord). These excessive forces cause shifting of the teeth and can relapse orthodontic treatment.

This condition is usually diagnosed when a patient brings the symptoms up to the attention of their dentist or doctor. In younger healthy patients with sleep-related bruxism, there is less sleep disruption.  Often jaw muscle pain affecting the masseter  (main cheek muscle) and temporalis (the muscle on the side of the head) muscles are reported with associated morning headaches. Fatigue in the muscles and limitation is opening upon waking are common with sleep-related bruxism. Recent studies have shown that younger patients (25-35) are present with more pain symptoms (tooth sensitivity, headaches, TMJ pain, muscle soreness), whereas patients 35+ present with more dental damage, antigonial notching, coronoid elongation, and other bone abnormalities.

Sleep-related bruxism can shorten the life of any standard OSA or bruxism appliance. Acrylic appliances can break under the increased force of sleep-related bruxism. This is a concern as small pieces of the broken appliance may be swallowed or aspirated into the lungs during sleep. The Luco Hybrid OSA Appliance is designed to withstand this and breakage is extremely rare (less than 3 cases in 3000). Because of this, this appliance can last in excess of 3 years with some lasting much longer.

There are several signs and symptoms related to sleep-related bruxism. It should be noted, however, that some people with this condition demonstrate very few symptoms and only experience disturbances in sleep. The following table outlines the signs and symptoms of sleep-related bruxism commonly seen:

Unpleasant tooth and muscle sensations Flattening or excessive wear of the teeth
Limitations of jaw movement, TMJ pain Fractured teeth and fillings, vertical cracks in teeth
Orofacial Pain (pain around the face region) Waking with the jaw locked, unable to open wide for a few minutes.
Temporal/tension headaches on waking or later in the day Abfraction lesions (painful notching of the roots at the gum line

Sleep-related bruxism varies considerably between individuals regarding intensity and duration. In most cases, it occurs hundreds of times a night. There is no direct link, however, between the severity of sleep-related bruxism and the symptoms that a patient may present to their dentist or doctor with. Sleep-related bruxism is rated by the number of bruxism events per hour (the bruxism index). Interestingly, patients with bruxism indexes of 2-4 per hour are much more likely to report muscle pain than more severe cases of > 4 per hour.

Psychological factors may also be linked to sleep-related bruxism. Currently, there is a weak correlation with psychological stress in both adults and children. Healthy patients with sleep-related bruxism patients tend to have higher scores regarding stress, anxiety, and psychiatric scales compared to patients without it. The studies for this are few and it is a weak link.

There are two subtypes of sleep-related bruxism: Primary sleep-related bruxism, which occurs without any clear cause, and Secondary sleep-related bruxism, which often occurs in children with medical diseases such as Cerebral Palsy, and other forms of mental retardation.  Myoclonus is a muscular disorder (either oro-mandibular or facio-mandibular) that is associated with SB in adults. Sleep-related breathing disorders (OSA and UARS) commonly occur with secondary sleep-related bruxism. Secondary sleep-related bruxism also occurs with obstructive sleep apnea as well as a result of certain medications.

Research has shown that sleep-related bruxism is highest in children at about 14-17%. In teenagers and young adults, it has been reported to drop to about 12%. It drops to 8% in young to middle age patients and down to around 3% in elderly patients. In the elderly, the significant drop may be due to decreased reporting and may be higher (as well as tooth loss).  Because of the overlap of symptoms of other conditions such as migraine syndrome (headaches in the same regions) and the variability in symptoms (some patients have no symptoms and would therefore not be included in these stats) many cases are not included. Clinically, however, most dentists see the results of SB much more often and more research is needed regarding the epidemiology of this disease.

As well, severe sleep-related bruxism in childhood may persist as severe throughout the lifetime of the patient. In these patients, the symptoms do not follow the normal progression of decreasing with age. There is also a relationship between Sleep-related bruxism in children and Attention Deficit Disorder Syndrome (ADHD), parasomnias  (such as confusion arousals, sleep-walking, sleep talking, head banging, and sleep relating eating disorder), sleep-related breathing disorders, snoring, and many psychological and medical conditions. Variability is high resulting in many patients not being diagnosed. Sleep-related bruxism occurring in childhood persists into adulthood in more than 65% of the cases!

Genetic patterns in sleep-related bruxism are probable as this tends to be seen in families with approximately 20-25% of affected patients having a close family member with a history of sleep-related bruxism. Certain gene mutations have been linked to sleep-related bruxism including the HTR2a gene and DDR3 gene, which reinforce the genetic inheritability theory.

Interestingly, This condition can start at any age. It is very difficult to study as the symptoms are so variable they are not reported by the patients to their doctors until the symptoms are affecting them significantly. The condition could have been present for years before being reported. Often the symptoms are not related to sleeping and are treated (sometimes inappropriately) as other conditions, leaving the condition untreated and allowing it to persist. As a result, few studies are conducted on this serious condition.

It should be noted as well that RMMA occurs in everyone. In normal sleep, RMMA is observed at about 1 episode per hour of sleep. However, with SRB the contractions are not only more often, but with much greater intensity (in the range of 10-14X normal chewing pressure). SRB also can vary considerably from night to night. Sleep studies can miss this at a rate of up to 25% of the time due to this nightly variability in many cases.

E.E.G. Findings:

Electroencephalogram (EEG) tracings have found differences between men who suffer from sleep bruxism. Women affected by sleep bruxism show a significantly lower Theta and Alpha EEG activity during sleep compared with normal subjects. This was found to be true regardless of the level of associated pain reported. When muscle recording is included in the EEG tracing, a significant increase in activity of the masseter and temporalis muscles is seen. This was associated with an increase in heart rate and blood pressure(TCR activation).

Clinical Findings:

Abnormal wear of the teeth and dental damage are the most common signs of SB. It is important though to differentiate SB and tooth wear from an abrasive diet which can look similar. Disorders of the TMJ are common (pain and clicking in the TMJ, closed locking).

Muscular Hypertrophy:

Hypertrophy or enlargement of the jaw muscles can occur in some people, primarily in the masseter and temporalis muscles. The following sections will outline the types of dental problems that are commonly seen with SB. The following image demonstrates hypertrophy or bulking up of the masseter muscle as is seen with severe sleep bruxism.

Fractured Roots: 

Although rare, root fractures are very painful and require urgent dental care (removal). Root fractures are caused by excessive lateral or side-to-side pressure on the teeth such as occurs in sleep-related bruxism or compression of the tooth due to tonic (clenching forces) on a heavily restored tooth.

Cracked Teeth:

These are common and also are very painful requiring urgent dental care (removal). Cracked teeth are caused by excessive vertical pressure or downward pressure on a tooth causing it to split through the roots. This can be caused by the pressure of sleep-related bruxism over time. Initially, the tooth will be hypersensitive to hot and cold as well as biting on hard foods. As it progresses, the symptoms worsen until the tooth cracks in two.

Cracked Fillings:

Fillings are not as strong as teeth and the effects of sleep-related bruxism accelerate damage to fillings. The life span of fillings in the presence of sleep bruxism is dramatically reduced.

Abfraction Lesions:

Painful notches at the neck of the tooth used to be blamed on aggressive tooth brushing. It is now known that this is a direct result of excessive lateral side-to-side pressure on teeth as is seen in sleep-related bruxism. The enamel at the gum line chips off and the exposed dentin, which is softer, wears away very quickly leading to the characteristic notches seen in abfraction lesions. These are challenging to manage as fillings do not hold well in these areas unless the source of the problem, sleep-related bruxism, is treated. Gum recession in the area of the abfraction lesion is common and can lead to bone loss between the teeth and loosening of the teeth. This results in extreme sensitivity of the teeth to touch, hot and cold!

Excessive Tooth Wear

Tooth wear is a normal part of aging. It becomes a concern when it occurs at an accelerated rate. With sleep bruxism, this frequently occurs often disfiguring the teeth or shortening them. In some cases, the shortening is so far that root canals become necessary due to exposure of the nerves. Sometimes the teeth are so badly worn they can only be removed. If this occurs in primary teeth in children, this can affect the position of the erupting permanent teeth as the permanent teeth only erupt to the height established by the primary teeth. Acid reflex associated with sleep-related bruxism (GERD) softens the enamel making it much less resistant to the forces of sleep-related bruxism and accelerated wear is often seen. This tends to be worse in men.


Other Dental Problems that Can Occur:

  • loosening of teeth due to excessive pressure during grinding, bone loss around the tooth, and/or stretching of the ligaments that attach the teeth to the jaw bone
  • acceleration of periodontal bone loss due to excessive loading of the teeth during sleep
  • fractured cusps of teeth (corners of the teeth breaking off)
  • hypersensitivity to hot, cold, and sweet
  • healthy teeth requiring root canal therapy for unknown reasons (due to the teeth being compressed into their sockets restricting blood flow into the tooth and tooth nerve death).

Chronic Myofascial Pain (CMP)

Myofascial pain refers to pain originating in the muscles and fascia covering of the muscles, which refers pain to adjacent regions or structures. The hallmark of myofascial pain is the development of trigger points, which are painful spasms inside a larger muscle group that feel like a knot or lump in the muscle. These muscle spasms can persist for months and even years and cause a myriad of symptoms. A primary trigger point can spread into other muscle groups and form secondary trigger points in adjacent muscles. In this way, the condition can spread and cause widespread pain symptoms. There is some evidence that CMP has a genetic basis and is activated by a trauma. In the case of sleep-related bruxism, the trauma is obvious: the overloading of the muscles.

When a trigger point develops in the muscles of the head and neck regions, the referred pain is interpreted as a headache. Depending which muscle is affected will determine where the headache occurs. It should be noted that hypoxia or low oxygen levels while sleeping also causes headaches (sleep apnea, UARS) from the low oxygen levels. There are a series of muscles of the jaws that are involved in opening, closing, retracting, advancing, and moving the jaw laterally side-to-side. The closing muscles are the chewing muscles however there are a series of neck muscles also involved that support the mandible, support the skull and support the neck when chewing. Sleep-related bruxism and UARS are both associated with chronic myofascial pain and the development of trigger points in these muscle groups. The following images show the most common areas in these muscles where trigger points commonly develop (x) and the expected referral patterns (headaches) from the trigger points (in red).

The Masseter Muscle

The Medial Pterygoid Muscle

 The Temporalis Muscle

 The Digastric Muscles

 The Sternocleidomastoid Muscle

 Trapezius Muscle

Jaw Problems: TMD (Temporomandibular Dysfunction)

Temporomandibular Dysfunction refers to disorders involving the TMJ or jaw joints. Excessive pressure exerted by the chewing muscles may cause a compression of the TMJ. This can trigger capsulitis of the back joint compartment of the TMJ resulting in severe pain when biting. This pain is caused by inflammation of the TMJ and, as it is encapsulated or in a capsule, the posterior or back joint compartment swells painfully forcing the entire mandible forward. This alters the bite resulting in difficulty closing the back teeth together and the front teeth hitting harder than normal. This is usually self-limiting and heals in a few weeks. It should be noted that patients with deep overbites can have this last much longer as their lower jaws naturally sit too far back. The back area of the TMJ is where all of the nerves and blood vessels reside. The American Academy of Sleep Medicine recognizes that patients with severe sleep-related bruxism can experience TMD problems and locking of the jaw upon waking is a common symptom in severe SRB.

 Normal TMJ Function: The disk (yellow in animation) stays between the bones at all times preventing bone wear and arthritis. The loading or pressure of the bite is directed through the disk at all times protecting the bones from damaging wear. There is never any pressure on the back portion of the joint and the nerves and blood vessels. (click to see animation)

Clicking TMJ: When the upper jaw does not develop to a normal size (as seen in many SB and OSA patients), the lower jaw can become too long for the upper. When biting, this excessive length of the lower jaw is expressed back towards the ear canals. The disk in the joint slips forward and, when the patient is biting, the TMJ becomes dislocated. On opening, the disk must re-seat into normal position with the characteristic click or popping sound. With this type of misalignment, the lower jaw is positioned too far back in the joint compressing the nerves and blood vessels of this region. Patients with clicking jaw are at much higher risk of capsulitis (pain and swelling of the TMJ) due to this positioning. Many chronic ear conditions can be attributed to capsulitis of the TMJ. This can also result in abnormal function of the Eustachian tubes resulting in difficulty in equalizing pressure in the inner ear.

The timing of the click in the opening cycle determines the prognosis for the TMJ. An early click, meaning the disk pops back into alignment quickly, indicates a relatively healthy disk. If the click is later, nearer to wide opening, the prognosis is not as good as the disk is dislocated for more of the opening cycle. If the ligaments that attach the disk to the jaw bone (condyle) stretch so much that they tear, a closed lock occurs.

Non-Reducing Closed Lock: This occurs when the disk tears free of the jaw bone sliding forward (and usually inward) blocking the normal movement of the jaw. This is often a very sudden and painful occurrence requiring urgent dental attention. If acute,  the jaw will be restricted to about 28mm and accompanied by severe muscle spasms on the affected side. If left untreated, it will stretch out to 32-34 mm but the muscles usually develop painful trigger points. A normal opening is 45-52 mm or three fingers wide, and about 10 mm left, right, and forward. With a closed lock, the jaw movement is blocked on the locked side so the jaw cannot move forward or to the side.  Typically, the jaw would deviate to the affected side as the healthy joint would move and the locked joint would not. If both joints are involved, there would be no movement to either side and no movement forward possible.

the American Academy of Sleep Medicine’s description of sleep-related bruxism states that waking with a closed lock, that resolves later in the day, is a common finding in this disorder.

Diagnosis of Sleep-Related Bruxism

There are three levels of accuracy in the diagnosis of this disorder:

Level One: the patient reports that they feel they have the condition. This is the lowest level of accuracy as it occurs when they are sleeping.

Level Two: the patient reports they feel they have it and their dentist finds signs of it in the patient such as tooth wear, broken teeth etc.

Level Three: the patient reports they feel they have it, their dentist finds signs of it, and it is recorded in a home sleep study.

As a rule, a dentist can initiate treatment with level two.

Limitation in opening is common due to myopathy, as are waking with headaches and headaches lasting into the day. Clenching is more common than grinding (tonic awake bruxism) in this group and damage to teeth such as excessive wear and abfraction lesions are also common (phasic awake bruxism). There is usually cervical (neck) involvement of the pain in TMD as many neck muscles are classified as accessory chewing muscles as they support the skull when chewing. Often there is a precipitating event (such as a whiplash injury, jaw injury, blow to the face, etc.). It should be noted, however, that SB and TMD can and do often occur in the same patients, as TMD patients may also have OSA or UARS predating the TMD. These are, by far, the most difficult patients to treat but also the most rewarding when treatment succeeds in treating both conditions. The Luco Hybrid OSA Appliance was designed specifically for these patients. It effectively treats TMD, chronic myofascial pain, sleep-related bruxism, snoring, and sleep apnea simultaneously. With thousands of patients treated, this appliance is clinically proven and very effective.

As discussed earlier, are some medical conditions that overlap symptoms with SB as well. Some of these include oro-mandibular myoclonus, facio-mandibular myoclonus, SRBD, RBD, abnormal swallowing, GERD, night terrors, confusional disorders, dyskinetic jaw movements persisting into sleep (dystonia, tremor, chorea, and dyskinesia) and rarely, sleep-related epilepsy. SRB is much more common than any of these disorders but they still must be considered before initiating treatment for SRB as they may require other medical treatments to manage.

Oro-mandibular or Facio-mandibular Monoclonus occurs in a fairly high number of SRB patients (10%). It is also seen in patients with excessive RMMA events during sleep. Facio-mandibular Myoclonus is much different than SRB. It consists of very short bursts of muscle activity of very short duration as opposed to longer sessions of grinding and clenching associated with SRB. This can only be diagnosed with a sleep study recording muscle activity.

With partial complex or generalized seizure disorder, rhythmic jaw movements are also seen. Because of this, these disorders should always be considered in the differential diagnosis of SRB and medical consultation is always prudent before treatment.

Until recently there were no recognized treatments of sleep-related bruxism. The Luco Hybrid OSA Appliance is the first and only recognized treatment of sleep bruxism to date, making this device truly unique, separating it from all other OSA and bruxism appliances.

In summary, sleep-related bruxism results in significant damage to the teeth, supporting bone, jaws, TMJ, and musculature.  It results in sporadic increases in blood pressure and heart rate, making it a risk factor for heart disease. Why are more dentists not treating it?

The Luco Hybrid OSA Appliance is the only sleep apnea appliance that is FDA-cleared for the treatment of patients suffering from sleep apnea and sleep-related bruxism. It is also the only treatment that reduces the effects of hyperstimulation of the Trigeminal Cardiac Reflex, as well as reducing the associated risk of heart disease to this hyper-stimulation.