How the Teeth are Affected by Sleep-Related Bruxism

The Most Common Symptoms of Sleep-Related Bruxism

The two most common symptoms for SRB are sensitivity of the teeth to temperatures, especially cold, and headaches, often in the temple regions. They occur most severely in the 25-35-year-old age group.

We will start by looking at sensitivity in the teeth and some of the ways sleep-related bruxism can cause this painful condition.


Sensitive Teeth:

Sensitive teeth are a direct result of the excessive forces placed on the teeth with SRB. The sensitivity is to temperature extremes such as ice water or hot coffee as well as to sweet foods and drinks and can be quite intense. This is one of the most commonly reported symptoms of SRB in all age groups.

There are three distinct types of sleep-related bruxism that occur: phasic or grinding of the teeth, tonic or clenching of the teeth, and mixed, which has characteristics of both. Figure 2 is a screenshot of a sleep study demonstrating the three types. the SRB burst can be seen to be much greater than the background jaw movements seen before and after the SRB events.

Figure 2 Types of Sleep-Related Bruxism

Phasic sleep-related bruxism occurs most frequently and creates a sheering or side to side force on the teeth. Tonic is a sustained contraction creating a compression-type force on the teeth. Mixed creates both types of forces.

These extreme forces are very damaging to the teeth and result in pain and sensitivity of the teeth. Ths following outlines the type of damage sleep-related bruxism causes to the teeth and what type of sleep-related bruxism is responsible for the damage.

Note that all of these effects result in sensitivity of the teeth, to temperatures (especially cold) and to biting.


Excessively Worn Teeth: Phasic 

Figure 3 Excessive Tooth Wear

With the nightly forces of SRB acting directly on the teeth, they wear down becoming shorter. This disfigures the teeth and exposes the softer underlying dentin of the teeth contributing to tooth sensitivity. GERD (gastro-esophageal reflux disorder or acid reflux) commonly occurs in sleep-related bruxism and the strong stomach acids soften the enamel of the teeth resulting in accelerated tooth wear in some. As the teeth wear, the pulp and nerves of the teeth are closer to the surface resulting in sensitivity to temperature.


Abfraction Lesions: Phasic

Figure 4: Abfraction Lesions

Abfraction lesions are notches that form at the gum line. It was believed that this was due to aggressive tooth brushing but this has now been shown not to be the case. The side-to-side grinding seen in phasic SRB rocks the teeth and the enamel at the gum line begins chipping off. A notch forces thinning of the tooth where it exits the jaw bone. The sensitive dentin is exposed. These abfraction lesions can be extremely sensitive to temperatures, sweet foods, cold drinks, as well as to touch. These are a common finding of SRB and can occur in upper and lower teeth on the outside of the teeth and less commonly, on the inside of the teeth. This results in sharp pain in the affected teeth with cold liquids.


Damage to the Periodontal Ligament (PDL) Phasic and Tonic

Each tooth is held to the jaw bone by a small series of ligaments called the periodontal ligament or PDL (Figure 5). The PDL is highly innervated by pain nerve endings (ask anyone who has had braces as these ligaments are being stretched constantly).

Figure 5 The Periodontal Ligament

This allows the tooth to move slightly during chewing to cushion to teeth slightly.

In SRB, the excessive pressure caused results in stretching or tearing of the PDL. The result is a sharp or dull pain in the affected teeth when biting as the injured periodontal ligament sends pain signals to the brain interpreted as the tooth hurting. The teeth may also feel loose as they have lost some of the periodontal ligament support.

Figure 6 Damage to the PDL from CompressiveTonic  forces


The nerve endings in the PDL are only the pain type and send pain signals to the brain that are interpreted as damage to the tooth. Many healthy teeth are treated inappropriately due to this referred type of pain from the PDL.



Cracked Fillings: Phasic and Tonic

Figure 7: Cracked Fillings

With the excessive forces of SRB on the teeth, fillings can break often shortly after being placed (figure 7). This can be costly and frustrating for both the patient and the dentist who placed the filling. Most filling materials have a compressive strength of less than the forces that SRB can generate.

Cracked fillings occur with all types of sleep-related bruxism. phasic sheering force can break off cusps or points of a filling whereas tonic compression type forces can overload the fillings causing them to crack and fall out.


Cracked Teeth: Phasic and Tonic

With the excessive compressive forces of SRB, the teeth themselves can crack or split. This is extremely painful when it happens as in figure 7. Often there is simply a small crack in the tooth that opens only when biting hard foods (resulting in a sharp pain that resolves immediately once the crack closes). Cracked teeth are very common. If caught early, a crown placed over the crack tooth can save it. Otherwise, the crack can deepen until the tooth splits and must be removed. Research has shown that the earlier a crown is placed on a cracked tooth, the better the long-term prognosis.

Figure 8 Types of Cracks in Teeth




Fractured cusps occur with phasic type sleep-related bruxism as the side to side grinding catches the cusps and can fracture them off.


Cracked Roots of Teeth: Tonic

Figure 9: Cracked Roots of the Teeth

Sometimes we see that the root of the tooth cracks. This requires a radiograph (x-ray) to identify. The tooth may feel loose and, if no previous root canal as in the image, is usually extremely painful. There is usually pain and swelling in the gum tissue around cracked roots and a deep periodontal pocket often forms around the crack. In most cases, the affected tooth must be removed (figure 9).


Fractured Dental Implants and Peri-Implantitis: Phasic and Tonic

Figure 10: Fractured Dental Implants

Dental implants are often placed to replace missing teeth or teeth badly damaged that cannot be saved. They are used as an anchor for fixed bridges as well. With the extreme forces of sleep-related bruxism, implants can be fractured during sleep (Figure 10).

Additionally, excessive side-to-side forces can result in peri-implantitis or bone loss around the implant similar to gum disease. This is due to the overloading of the implant and side-to-side rocking of it (figure 11).

Figure 10: Peri-Implantitis


As you can see, untreated sleep-related bruxism can be very damaging to your teeth. The Luco Hybrid device is the only FDA treatment of any type, for sleep-related bruxism and eliminates these effects from occurring or worsening.

Let us now look at the second most common symptom of sleep-related bruxism: Headaches.



Headaches are one of the most common diseases affecting the population. Tension headaches occur in more than 70% of the population and occur equally in men and women whereas migraine headaches occur in 14% of the population with women twice having as many migraine headaches as men.

Sleep-related bruxism is related to both of these types of headaches.


Tension-Type Headaches and Sleep-Related Bruxism

Sleep-related bruxism has a genetic component, an excessive number of HTR2a genes on chromosome 13. This gene creates receptors in the nervous system for serotonin, a powerful neurotransmitter. Interestingly, tension headaches also share this mutation.

Sleep-related bruxism directly affects a protective reflex called the masseter inhibitory reflex or MIR. it is a protective reflex that inhibits or prevents contraction of the masseter muscles.

The MIR is activated when you unexpectedly bite into something hard in a softer food. as soon as you bite the object you stop chewing. You remove the object and then slowly resume normal chewing. This is the MIR in action. It is a protective reflex to prevent damage to the teeth, jaw joint or TMJ, and chewing muscles. \

The MIR is made up of two distinctive phases: the ES1 and the ES2 phases

Figure 11: The Phases of the Masseter Inhibitory Reflex

The Es1 phase occurs very quickly, within 10 milliseconds after biting the hard object. The second phase occurs after 40-50 ms. Both phases prevent the masseter muscle from contracting.

In sleep-related bruxism, the ES1 and Es2 phases are reduced or eliminated.

Figure 12: How Sleep-Related Bruxism and Tension Headaches Affect the MIR

In figure 12, the ES1 phase is reduced and the ES2 phase is missing. The protection is lost. Of note, compare the upper and lower tracings in Figure 12. They are very similar indeed. Sleep-related bruxism and tension headaches both affect the MIR similarly.

But how does this translate into tension headaches?

The loss of the MIR protection allows the masseter muscle to contract with 100% of its force during sleep-related bruxism events. This can lead to injury of the muscle and the development of myofascial trigger points within the muscle. These are painful “knots” of contracted muscle tissue that can refer pain to adjacent regions and structures. In sleep-related bruxism, both the masseter and temporalis muscles are affected.

Figure 13: Excessive Contraction of the Masseter and Temporalis Muscles

Both of these muscles have predictable pain referral patterns that are interpreted as tension-type headaches.

Figure 14: Pain Referral Pattern for the Masseter Muscle

Note that the pain referral pattern for the masseter muscle is upper and lower teeth (yet another cause of sensitive teeth!), the maxillary sinuses, and over the eyes and temple regions.

Figure 15: Pain Referral Patterns for the Temporalis Muscle

The temporalis muscle is also affected by suppression of the temporalis inhibitory reflex. The pain referral pattern in figure 15 demonstrates the sensitivity of all of the upper teeth, over the eyes, the temple region, and the side of the head.

These two pain referral patterns constitute tension-type headaches. The upper trapezius and sternocleidomastoid muscles are accessory muscles of mastication of chewing and may exhibit specific muscle pain referral patterns in addition to the masseter and temporalis.


Migraine-Type Headaches and Sleep-Related Bruxism

Only migraine headaches without a prodromal aura are related to sleep-related bruxism. Migraine headaches affect the temporalis inhibitory reflex by suppressing the ES2 phase allowing the temporalis to contract with 100% force. With the sleep-related bruxism affecting both the masseter and temporalis inhibitory reflexes, it is easy to see the relationship.


How the Luco Hybrid Device Treats Tension and Migraine Headaches

The patented forward bite of the Luco Hybrid device reduces the force of bite of the masseter and temporalis muscles to normal levels, by activation of the periodontal masseter reflex by stimulation of the upper cuspids and first bicuspids.


Figure 16: The Periodontal Masseter Reflex

When the cuspid or first bicuspid are stimulated by the forward bite, an inhibitory signal is sent to the masseter muscles, preventing them from contracting further. This effectively stops the sleep bruxism events from occurring:

Figure 17: How the Luco Hybrid Device Reduces Sleep-Related Bruxism

As can be seen in Figure 17 above, treatment with the Luco Hybrid device eliminates sleep-related bruxism and restores normal muscle activity.