Bruxism is defined as ‘a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth as well as bracing or thrusting of the mandible.’ Bruxism occurs in adults and children, with a systematic review reporting an incidence of 18.6% in adults.

TMJ and Bruxism

A definitive study conducted by researchers at New York University (NYU) College of Dentistry, Weill Cornell Medical College, New York and the University of Montreal led by NYU investigator Karen Raphael concluded that bruxism does not cause TMJ disorders and there is no relationship between the two.

Dr. Karen Raphael stated, “When your dentist tells you that your facial pain is somehow ‘your fault’ because you are grinding your teeth, you now know that it is simply not true. Many people grind their teeth a little bit at night, but that activity cannot account for your pain. If anything, people who suffer from the most severe TMJ pain are actually the least likely to grind their teeth at night. If you are thinking about getting treatment for sleep grinding to help reduce your pain, think again: It is likely to be a waste of time, energy and money.”

Sleep Bruxism

A long-held belief by many patients and dentists is that jaw problems are caused by tooth-grinding (bruxism) during sleep. According to the 2020 NAM report (page 3-20), “sleep bruxism has also been linked with TMJ [disorders] in some studies; however, recent meta-analyses describe the evidence linking sleep bruxism and TMD pain as inconclusive (Jimenez-Silva et al., 2017; Baad-Hansen et al., 2019).” Other investigators (Lund, Raphael) have shown that the linkage between sleep bruxism and jaw pain problems is relatively minimal.

It has been shown that the oral activities of sleep bruxism are part of the normal sleep cycle. While almost everyone bruxes during sleep, if you do it excessively, it can be legitimately labelled as true sleep bruxism. This is measured in a sleep lab.

There are no preventive treatments for sleep bruxism, so the only treatment that may be helpful is wearing a plastic nightguard – mainly to protect the teeth from excessive wear.

Awake Bruxism

During the daytime, some people may engage in various “abnormal” oral behaviors like clenching, biting on objects (e.g., pencils), and nibbling on tongue or cheeks, etc. The only treatment approach for this problem is behavioral training.

Drug-Induced Bruxism

Bruxism is an under-recognized adverse drug reaction particularly associated with use of antipsychotics and selective serotonin reuptake inhibitors.

Orofacial manifestations of drug-induced movement disorders are significant adverse effects which can affect both quality of life and medication adherence. Raising awareness of this often-overlooked adverse effect is therefore essential.

Teoh L, Moses G. Drug-induced bruxism. Aust Prescr. 2019;42(4):121. doi:10.18773/austprescr.2019.048

We thank Charles S. Greene, D.D.S., Clinical Professor, Department of Orthodontics, UIC College of Dentistry, Chicago, IL for his assistance in writing this section.