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The Use of Night Guards Revisited by Drs. Barry Glassman and Don Malizia

View Comments (3) More by Don Malizia (2)More by Barry Glassman, DMD, FAACP, DAAPM, FICCMO (4)
Categories: TMJ and Occlusion;
The Use of Night Guards Revisited 

The importance of a comprehensive history in the consideration of appliance design

by Drs. Barry Glassman and Don Malizia

Dental “night guards” are full arch, often flat-planed appliances prescribed by dentists to protect teeth from damage caused by grinding or clenching during sleep. These custom-fitted devices are inserted to act as a physical barrier, preventing the wear and tear of enamel, as well as having the potential to alleviate pressure on the teeth. Although night guards may alleviate actual dental pressure, they may increase the magnitude of the force vectors that result in increased strain and sprain of the weak links of the craniomandibular system. Included in the potential areas of increased stress and peripheral damage are the enthesis of the stylomandibular ligament, the temporal tendon and the attachments of the deep cervical musculature.1–2

In addition to the peripheral injuries, these traditional full arch full-contact night guards can result in increased trigeminal signaling centrally. Therefore, while night guards are highly effective at protecting the integrity of teeth, they are not specifically designed to address more complex issues such as temporomandibular joint (TMJ) dysfunction or chronic jaw pain.

Therefore, the mechanisms of dental night guards prescribed for patients should be considered while keeping in mind the risks and benefits of their use. A more comprehensive diagnosis, which considers signs and symptoms that the patient may not associate with bruxism and that only come to our attention with a more complete history, is extremely important. Only with this information can we decide whether the usual and customary design of the night guard being prescribed is appropriate. While flat-planed full arch appliance does have a specific purpose, they often fall short in treating joint-related or trigeminally mediated conditions.


The primary purpose of dental night guards
Night guards are specifically engineered to shield the teeth from the harmful effects of nocturnal activities such as grinding and clenching. Bruxism, which affects a significant portion of the population, can lead to enamel erosion, cracked teeth and even tooth loss over time. By creating a protective barrier between the upper and lower teeth, the goal of the night guard is to minimize the direct contact that leads to dental wear and increased dental mobility.


Understanding TMJ dysfunction and its complexity
The material of night guards, which are often made from hard acrylic or softer thermoplastic, absorbs the pressure exerted during clenching or grinding. While a traditional night guard may reduce the risk of dental trauma, it is often proposed that night guards will help relax the jaw muscles to a degree. There is no proposed mechanism to suggest the alteration of muscle function. The appliance’s effectiveness is limited to protecting the teeth and does not extend to the underlying causes or symptoms of joint or muscle dysfunction.

TMJ dysfunction refers to a range of disorders affecting this joint and the surrounding muscles. Symptoms may include the following:
  • Jaw pain or tenderness
  • Difficulty opening or closing the mouth
  • Clicking or popping sounds in the jaw
  • Headaches, earaches or neck pain
Unfortunately, TMJ dysfunction has long been used as a diagnosis, even though the term encompasses many different disorders.3


Is there a cause for bruxism?
Great efforts have been made since 2013 to define bruxism.4 The latest definition for sleep bruxism (SB) is: SB is a masticatory muscle activity during sleep that is characterized as rhythmic (phasic) or non-rhythmic (tonic) and is not a movement disorder or a sleep disorder.5 It is therefore considered a behavior.6 The concept that bruxism is a “behavior” rather than a pathological activity with a peripheral cause (interferences or malocclusion) is consistent with the studies that make it clear that bruxism is a centrally mediated activity.7

The causes of TMJ dysfunction are multifaceted, often involving a combination of muscular issues, joint ligament laxity, associated internal derangements, arthritis and psychological factors like stress. Unlike teeth grinding, TMJ disorders are not limited to mechanical wear and tear but involve deeper anatomical and neurological components.


Why night guards fall short in treating TMJ dysfunction
1. Lack of direct impact on joint mechanics
Night guards are designed to modify the interaction between the upper and lower teeth, not to alter the function of the temporomandibular joint. While they can sometimes redistribute the forces exerted during grinding or clenching, they do not address the underlying joint mechanics or neurobiology of the central nervous system and the trigeminal system. In fact, there is at least the potential for there to be increased electromyography (EMG) activity of the elevator musculature in the presence of the night guard as opposed to contact of the dentition itself.

2. Role in pain management and joint dysfunction
One of the most distressing symptoms of trigeminally mediated pain is when the pain becomes chronic. Unfortunately, night guards offer no mechanisms to alleviate this pain, as their focus is purely on protecting dental enamel. Pain management for TMJ dysfunction and orofacial pain disorders often requires a multidisciplinary approach, including medications (such as muscle relaxants or anti-inflammatories), counseling to manage stress and other targeted therapies.

In addition, if the night guard has significant retention, there is the potential for afferent nociception to play a role in increased trigeminal signaling, leading to hyperalgesia or even allodynia.

There is significant evidence demonstrating that the elevated EMG activity in the musculature that results in increased magnitude and direction of the forces created by bruxism is triggered with posterior contact. Numerous studies demonstrate that appliances that limit or eliminate posterior contact result in decreased EMG activity, therefore reducing the magnitude of the force vectors resulting from the contact into the trigeminal-cervical mandibular system. This explains the shortened arch concepts, which have been shown to decrease forces.8

In addition, it has been shown that with the lack of posterior contact, there is reduced upper airway resistance, reduced nasal inflammatory states and reduced cerebral blood flow, all of which are elevated with the posterior contact associated with full arch night guards. Night guards without posterior contact have the potential to decrease the intensity and frequency of migraine headaches.9

3. Bruxism and sleep disorders
While the American Dental Association has recommended all patients be screened for sleep-disordered breathing, it is estimated that the vast majority of dental offices are not screening as recommended. It should not be assumed that there is a direct causal relationship between sleep-disturbed breathing and the presence of nocturnal bruxism. Bruxism has been shown to be associated with micro-arousals and can exist in the absence of sleep-disturbed breathing.

There is, however, a complex severity of obstructive sleep apnea (OSA) dependent association with sleep bruxism. About one-third of OSA patients will show phasic sleep bruxism, more in mild to moderate OSA than in severe OSA.10 There has also been some evidence to suggest a possible increase in obstructive sleep disorders with the use of full arch maxillary night guards.11

4. Overemphasis on teeth protection
In some cases, the use of night guards for patients with orofacial pain, headaches or temporomandibular joint dysfunction can be problematic. Patients may believe that wearing a night guard will resolve all their symptoms, including joint pain, when in fact, the device’s efficacy is limited to preventing further dental damage. This misuse of an appliance without the mechanism to resolve their symptoms may increase the frequency and significance of symptoms, and at the same time, delay appropriate treatments for TMJ dysfunction.


Conclusion
While full arch flat full-contact night guards can play a crucial role in protecting teeth from the damaging effects of grinding and clenching, the limitations of their potential to address TMJ dysfunction, joint pain and orofacial pain patterns are clear. These devices, as usually designed, have no direct mechanisms for improving joint function, treating internal derangements, decreasing pain in joint arthritis, relieving muscle tension or managing chronic pain.

Patients experiencing symptoms of TMJ dysfunction, orofacial pain, cervicogenic pain, chronic pain and headaches should seek a comprehensive evaluation to determine the most appropriate treatment plan rather than relying solely on a night guard designed to protect teeth.

It has been suggested that a comprehensive history is critically important to identify those patients who have some degree of joint dysfunction or a trigeminally mediated disorder. There has been much recent work on central sensitization in chronic pain.12 This central sensitization is not only involved in orofacial pain, but also in other conditions collectively known as chronic overlapping pain conditions.13–14 A simple full-body pain map in your history can help identify these patients.15

The history should include screening for a sleep-disturbed breathing condition. If there is a risk of OSA, a sleep study determines the diagnosis, and an oral appliance can manage both the OSA and the SB.16–17 There is data to show that a sleep appliance can reduce bruxism events.16–17

If it is determined that a nocturnal appliance is to be used, an alternative design with the purpose of decreasing trigeminal signaling could be considered. Simply using a traditional night guard with vulnerable patients who have peripheral injuries or an altered central nervous system could initiate symptoms or potentiate their existing condition. A multidisciplinary approach involving dental, medical and therapeutic interventions often proves most effective in managing this complex condition.

References
1. Palesy, P.D., Tendon and ligament insertions—a possible source of musculoskeletal pain. Cranio, 1997. 15(3): p. 194-202.
2. De Lorenzis, E., et al., Concepts of entheseal pain. Arthritis & Rheumatology, 2023. 75(4): p. 493-498.
3. Nitzan, D.W., B. Kreiner, and R. Zeltser, TMJ lubrication system: its effect on the joint function, dysfunction, and treatment approach. Compend Contin Educ Dent, 2004. 25(6): p. 437-8, 440, 443-4 passim; quiz 449, 471.
4. Lobbezoo, F., et al., Bruxism defined and graded: an international consensus. J Oral Rehabil, 2013. 40(1): p. 2-4.
5. Verhoeff, M.C., et al., Updating the Bruxism Definitions: Report of an International Consensus Meeting. Journal of Oral Rehabilitation, 2025.
6. Raphael, K.G., V. Santiago, and F. Lobbezoo, Is bruxism a disorder or a behaviour? Rethinking the international consensus on defining and grading of bruxism. Journal of Oral Rehabilitation, 2016. 43(10): p. 791-798.
7. Lobbezoo, F. and M. Naeije, Bruxism is mainly regulated centrally, not peripherally. J Oral Rehabil, 2001. 28(12): p. 1085-91.
8. Hattori, Y., et al., Occlusal and TMJ loads in subjects with experimentally shortened dental arches. J Dent Res, 2003. 82(7): p. 532-6.
9. Blumenfeld, A.M. and J.P. Boyd, Adjunctive Treatment of Chronic Migraine using an Oral Dental Device: Overview and results of a Randomized Placebo-Controlled Crossover Study. BMC Neurology, 2022. 22(1): p. 1-9.
10. Ferreira, I.R., B.M.G. Pinto, and C.C.d. Paula, Relationship between sleep bruxism and obstrutive sleep apnea: A literature review. Research, Society and Development, 2023. 12(6): p. e3412641925.
11. Gagnon, Y., et al., Aggravation of respiratory disturbances by the use of an occlusal splint in apneic patients: a pilot study. Int J Prosthodont, 2004. 17(4): p. 447-53.
12. Harte, S.E., R.E. Harris, and D.J. Clauw, The neurobiology of central sensitization. Journal of Applied Biobehavioral Research, 2018. 23(2): p. e12137.
13. Schrepf, A., et al., The Chronic Overlapping Pain Condition Screener. The Journal of Pain, 2024. 25(1): p. 265-272.
14. Johnston, K.J.A., R. Signer, and L.M. Huckins, Chronic overlapping pain conditions and nociplastic pain. HGG Adv, 2025. 6(1): p. 100381.
15. Clauw, D.J., Why don’t we use a body map in every chronic pain patient yet? PAIN, 2024. 165(8).
16. Franco, L., et al., A Mandibular Advancement Appliance Reduces Pain and Rhythmic Masticatory Muscle Activity in Patients with Morning Headache. J Orofac Pain, 2011. 25(3): p. 240-249.
17. Abe, S., et al., Oral appliances reduce masticatory muscle activity-sleep bruxism metrics independently of changes in heart rate variability. Clinical Oral Investigations, 2022. 26(9): p. 5653-62.
Author Bios
Dr. Barry Glassman Dr. Barry Glassman is a diplomate of the American Academy of Craniofacial Pain, the American Academy of Pain Management, the American Academy of Dental Sleep Medicine, and a fellow of the International College of Craniomandibular Disorders. He serves as the Director of Education for Dedicated Sleep. He was on the Lehigh Valley Hospital network staff and served as a clinical instructor in craniofacial pain and sleep disorders. He continues teaching in dental sleep medicine and orofacial pain and is a popular international lecturer.


Dr. Don Malizia Dr. Don Malizia is a practitioner focused on upper-quarter chronic pain and sleep-disturbed breathing at the Allentown Pain & Sleep Centers in Allentown and Wilkes- Barre, Pennsylvania. He is currently on the faculty of the Department of Education for Dedicated Sleep.



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