Sleep Bruxism – Are Dentists Harming Patients?  

Vesna S Sutter DDS and Louis Malcmacher DDS MAGD

Abstract:

Sleep bruxism (SB) is a known parasomnia in sleep medicine reported by approximately 8% - 15% of the adult population. It has been recognized for many years that a relationship exists between Nocturnal Bruxism (NB) and Obstructive Sleep Apnea (OSA), but why and how direct is yet unknown.The purpose of the study is to establish if there is a direct link between OSA severity and SB severity, and if yes how strong. Random patients were divided into three categories of OSA, mild, moderate, and severe. Their sleep studies where analyzed for correlations between OSA severity and Sleep Bruxism severity. The results showed that there was no direct linear correlation, but the research did show that close to 80% of the OSA patients had SB. This is a much higher relationship than currently thought.

Method:

1000 subject’s home sleep tests (HST) using the STATDDS Home Bruxism and Sleep Monitor were divided into three categories of sleep. Those with an Apnea/Hypopnea Index (AHI) below 5 episodes per sleep hour were eliminated from the study.  The three groups were: mild, moderate, and severe.  The criteria for the categories was:

1. Mild is AHI of 5 to 15
2. Moderate is 15 to 30
3. Severe is 30 or higher

Then 15 subjects were selected from each category, totaling 45 subjects included in the analysis. Once the subjects were selected the Bruxism Episode Index (BEI)¹ and the Bruxism Burst Index (BBI)¹  were calculated.

 For this study the BEI was used to categorize each group of subjects into 2 sub-categories:

(1) Significant Bruxism having BEI 2.5/hr but < 4/hr

(2).Diagnostic Criteria for Bruxism having  BEI  > 4/hr      

 Results:

The following graph shows the data that was collected and the definitions used to score the bruxism episodes.

 From the graph it can be concluded that bruxism severity and OSA severity are not linearly related. The more severe the OSA is does not mean that the more severe the bruxism episodes will be. However the data does show us that the percentage of OSA patients that also exhibit SB is much higher than expected. In the Mild group of the 15 subjects 86% had a significant BEI; in the same group 8 subjects showed diagnostic BEI greater than 4/hr. In the severe grouping the percentages were very similar to the mild, 86% had a significant BEI. The moderate category in this random selection of subject showed a slightly lower percentage of 66%, but that figure is still higher than currently thought.

  How does this new information affect dentists across the country? Since the presence of OSA is so high in bruxism patients, all patients that are prescribed a night time bruxism appliance should first have a diagnostic sleep study done  to see if  OSA is present. In the United States alone, some 1.6 million splints (AKA nightguards, biteguards, occlusal splints, biteplates, removable appliances, or interocclusal orthopedic appliances) are annually prescribed by dentists in an effort to combat bruxism⁴. According to our study, that would mean that approximately 80% of those patients totallying  1.28 million may also suffer from or have OSA. These patients very well may have a bruxism appliance that may not only be the correct or proper appliance to treat their SB/OSA condition, their bruxism appliance could be very harmful to the patient by blocking their airway and exacerbate their OSA.  The authors combined have 75+ years of experience in dentistry and not once have we ever seen a patient die of bruxism.  Patients do suffer from life threatening OSA or other severe medical conditions that are made worse by OSA.. We as dentists treating bruxism need to see this correlation and accept that we can make a huge impact on patient’s health by working with their physicians in screening for bruxism ad OSA before fabricating a occlusal splint. You can see in the figure below how the AHI and BEI cluster together. Of course not all patients that exhibit clenching and teeth grinding have OSA, but the correlation is high enough that they should be properly evaluated before any kind of treatment.

 What is bruxism and why do people do it? The word bruxism is taken from the Greek word brychein: gnashing of teeth. No standard terminology yet exists. Bruxism can, perhaps, be best defined as the involuntary, unconscious, and excessive grinding or clenching of teeth. When it occurs during sleep, it may be best referred to as sleep bruxism. A few people, on the other hand, brux while they are awake, in which case the condition may be referred to as wakeful bruxism. Awake bruxism is thought to have different causes than sleep bruxism, and is more common in females, whereas males and females are affected in equal proportions by sleep bruxism.⁵

 Sleep Bruxism is a type of sleep-related movement disorder that is characterized by involuntary masticatory muscle contraction resulting in grinding and clenching of the teeth and is typically associated with arousals from sleep.^2,3 According to the International Classification of Sleep Disorders revised edition (ICSD-R), the term "sleep bruxism" is the most appropriate diagnosis code since this type occurs during sleep specifically rather than being associated with a particular time of day, i.e., if a person with sleep bruxism were to sleep during the day and stay awake at night then the condition would not occur during the night but during the day. The ICDS-R defined sleep bruxism as "a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep",⁶ classifying it as a parasomnia. The second edition (ICSD-2) however reclassified bruxism to a "sleep related movement disorder" rather than a parasomnia.  Jerald H Simmons, MD, recognized the relationship of these conditions, with Ron Prehn, DDS,  they studied more than 700 patients with OSA and came to the conclusion that night time bruxism is an attempt to bring the jaw and tongue forward. Bruxism stops the back of the tongue from blocking the airway and is the brains way of preventing obstruction. This masseter muscle activity can be seen on EMG during a polysomnography.

Figure1: Hypnogram and polysomnographic tracings showing an episode of rhythmic masticatory muscle activity (RMMA) during sleep.

 Figure 2: Four respiratory effort–related arousals (RERAs) are shown. Each RERA is followed by an episode of bruxism as seen in the chin EMG

 Current research being done by the STATDDS clinical support team reveals that an occlusal splint in an OSA patient can worsen the OSA in some case.  For this reason alone, all dentists should be testing their occlusal splint patients for OSA. We need to know what condition we are treating before making an appliance and not put our patient’s health at risk. Of the fourteen patients evaluations post splint therapy, more than 50% of their OSA worsened. Dentists providing occlusal splint therapy to their bruxism patients, who may have undiagnosed OSA, could be seriously harming their patients by closing their airway while trying to improve their bruxism.  Closing the patient’s airway with a bruxism appliance puts the patient and the dental clinician at enormous risk from a health and liability standpoint.

Conclusion:

The etiology of bruxism is controversial and uncertain. ^7,8  At present, the causes are suspected to be many, to overlap each other, and to vary from one patient to another. Some causes include stress, personality types, allergies, nutritional deficiencies, malocclusion, dental manipulations, introduction of foreign substances into the mouth, central nervous system malfunction, drugs, deficient oral proprioception, and genetic factors. Even though the etiology of bruxism is uncertain, it’s correlation to OSA in certain. It is evident that only during a specialized sleep study in which a bruxism EMG sensor is used can we diagnose if the airway is being compromised either as a baseline study or with the patient wearing any kind of dental appliance. Possible airway obstruction during sleep is a highly comorbid condition with bruxism and dentists need to work with physicians to help improve patient health.  This article shows that the wrong bruxism appliance can seriously and negatively affect the patient’s health and it is the dentist’s responsibility to have evaluated the patient’s airway with a home bruxism/sleep monitor (STATDDS) before any appliance or other treatment is rendered.

Reference List:

1. J Dent Res.1996 Jan;75(1):546-52.

Sleep bruxism: validity of clinical research diagnostic criteria in a controlled polysomnographic study.

Lavigne GJ, Rompré PH, Montplaisir JY.

2. Macedo CR, Macedo EC, Torloni MR, Silva AB, Prado GF. Pharmacotherapy for sleep bruxism. Cochrane Database Syst Rev. 2014;10:CD005578.

3. Carra MC, Huynh N, Lavigne G. Sleep bruxism: a comprehensive overview for the dental clinician interested in sleep medicine. Dent Clin North Am. 2012;56(2):387-413

4. Pierce, C. J., & Gale, E. N. (1988). A comparison of different treatments for nocturnal bruxism. Journal of Dental Research, 67, 597-601.
5. Shetty S, Pitti V, Satish Babu CL, Surendra Kumar GP, Deepthi BC (September 2010). "Bruxism: a literature review". Journal of Indian Prosthodontic Society
6. International classification of sleep disorders, revised: Diagnostic and coding manual." (PDF). Chicago, Illinois: American Academy of Sleep Medicine, 2001. Retrieved 16 May 2013.
7. Ellison, J. M., & Stanziani, P. (1993). SSRI-associated nocturnal bruxism in four patients. Journal of Clinical Psychiatry, 54, 432-434.
8. Thompson, B. H., Blount, B. W., & Krumholtz, T. S. (1994). Treatment approaches to bruxism. American Family Physician, 49, 1617-22