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Teeth Grinding

Causes and Therapies for a Potentially Troubling Behavior

By Dr. Louis R. Marion

Teeth grinding.

Was life in the late Middle Ages as stressful as it is today? It could have been — especially if you were desperately trying to hang on to the crown, and pitted against formidable enemies. That was exactly the situation English King Richard III — the historical monarch whom Shakespeare famously portrayed as a scheming, hunchbacked villain — found himself in around five centuries ago.

Anthropologists examining the King's skeletal remains, which were recently discovered beneath a parking lot in the city of Leicester, England, were able to reconstruct a number of details about his life. Their evidence indicates he had severe injuries from battle wounds, a curved spine from scoliosis…and, according to one researcher, characteristic patterns of wear on his teeth that show he suffered from bruxism, or teeth grinding. Whether it was related to stress or anxiety can't be known for sure, but his remains do support the evidence found in museum laboratories and dental clinicians' chairs, that bruxism leads to severe dental wear or attrition.

What exactly is bruxism? According to the glossary of the Academy of Prosthodontics, the word refers to the parafunctional ("para" – outside; "function" – job or duty) grinding of teeth: "an oral habit consisting of involuntary rhythmic or spasmodic nonfunctional gnashing, grinding, or clenching of teeth, in other than chewing movements of the mandible." In other words, the stress bruxism places on the teeth and jaw muscles are outside of the normal range of chewing, biting, etc.

It is thought that around one in ten adults experience problems stemming from bruxism, making it one of the most common parafunctional habits related to the mouth. It's even more common in children — but unless it causes severe problems, like pain or sleep difficulties, kids are rarely treated for it.

In recent years, dental researchers have studied bruxism extensively. At present, there's still plenty of disagreement about exactly what causes it, what strategies are best for treating it…even whether or not an individual needs treatment at all. A closer look at this condition shows why diagnosing and managing it can pose challenges.

The Causes of Bruxism: It's all in your head?

It seems clear that bruxism can arise from a number of different causes. At one time, scientists believed it was principally caused by anatomical differences in the human bite: Since people aren't born with perfectly aligned teeth, the attrition (erosion of tooth surfaces) from bruxism was thought to make the bite actually work better — in other words, you could grind your way to a better bite. Orthodontist and researcher of occlusion Percy Raymond Begg published the results of his work with ancient and modern day hunting and gathering populations supporting the idea that dental wear and grinding allows the human bite to adapt and avoid malocclusion (mal – bad, occlusion – bite). With such grinding and adaptation, many researchers have seen exceptionally low rates of malocclusion in certain populations. Renowned anthropologist Richard S. Corruccini termed malocclusion a "disease of civilization" since, over time, malocclusion rates have steadily increased as humans adopted a more refined diet.

Researchers currently tend to divide bruxsim into two separate categories: daytime (diurnal) grinding, which occurs while you are awake, and nighttime (nocturnal) grinding that occurs while you are asleep.

Today, many believe that other factors also play a significant role in bruxism. Researchers currently tend to divide bruxsim into two separate categories: daytime (diurnal) grinding, which occurs while you are awake, and nighttime (nocturnal) grinding that occurs while you are asleep. While the study of daytime bruxism mostly relies on patients reporting their own symptoms, nocturnal bruxism can be carefully monitored by instruments in a sleep lab.

Recent research on nocturnal bruxism has led to some new insights about this behavior: It seems to be related to a pattern of brain activity that happens during the sleep cycle. This pattern, called the arousal response, occurs when an individual passes between states of deeper and lighter sleep or wakefulness. Several studies indicate it can trigger muscular activities that result in teeth grinding. Based on this research, the American Academy of Sleep Medicine now classifies nocturnal bruxism as a sleep-related movement disorder. That classification makes sense, as studies have shown that nocturnal teeth grinding is strongly associated with habitual snoring and other sleep disorders.

The brain's role in facilitating bruxism could also help explain some of the other factors that are thought to cause this behavior. For example, it has been observed that long-term use of psychoactive drugs, such as certain SSRIs (selective serotonin reuptake inhibitors) and amphetamines, is associated with bruxism. It's possible that these drugs affect the transmission of nerve impulses in such a way that they trigger the response.

Brain chemistry could also explain why tobacco users report twice the incidence bruxism compared to non-users: The powerful effects of nicotine may be to blame for this condition (not to mention many others). The excessive use of caffeine, alcohol and illicit drugs has also been reported to trigger teeth grinding. The condition is often observed in people with Parkinson's disease, a condition which affects nerve cells in the brain.

Other Factors

Yet brain chemistry and sleep disorders don't sufficiently explain daytime teeth grinding — and they don't tell us why some people are affected and others aren't; so it's clear that there is more to this picture. One additional factor may be genetics, which seems to make some people more likely to develop this condition. Furthermore, while anecdotal evidence isn't as easy to measure as lab tests, many reports suggest that bruxism has a psychological or emotional aspect. And the factor most commonly associated with this condition is stress.

Teeth-clenching seems to fit the stereotype of a hard-driving, type-A individual — and research shows the prevalence of this behavior isn't just typecasting.

Teeth-clenching seems to fit the stereotype of a hard-driving, type-A individual — and research shows the prevalence of this behavior isn't just typecasting. A number of studies point to the difference between those who grind their teeth and those who don't. Bruxers tend to have higher levels of anxiety, stress sensitivity, depression and hostility. In fact, a large, multi-national study named anxiety and sleep-related breathing disorders as the two most common risk factors for bruxism.

Diagnosing Bruxism

If teeth grinding occurs at night, how do you know if you are doing it? If you sometimes clench your teeth in the daytime, when does this behavior become a concern? There's no simple answer to those questions…but there are a few guidelines.

From time to time, people find themselves clenching their teeth — especially in times of stress. This isn't abnormal — and in many cases, simply becoming aware of this behavior can help you limit it. If it recurs frequently, however, it may be time to seek treatment. Occasionally at night, a relative or sleeping partner may notice unexpectedly loud, grating sounds. On closer inspection, they may find that those jarring noises are produced by teeth grinding. Sometimes — especially in children — the behavior may be a temporary phase that soon goes away on its own. But it if persists, or causes other problems, it should be taken more seriously.

It is thought that perhaps half of all bruxers develop significant problems from the forces unleashed by teeth grinding. Some of the issues most commonly reported are tenderness in the jaw, persistent headaches, and sore teeth. In some cases, teeth grinding can cause damage to dental work like crowns and bridges. It may also cause excessive tooth wear, and in severe cases can fracture or loosen teeth. At that point, it's time for a dentist and/or medical specialist to intervene.