Tag: Head (Body Part)

Grind Your Teeth? Your Night Guard May Not Be the Right Fix

Grind Your Teeth? Your Night Guard May Not Be the Right Fix

Some experts say tooth-grinding is a behavior rather than a disorder, and the dentist’s chair isn’t the best place to address it.

Credit…Jon Han

  • Feb. 16, 2021, 5:00 a.m. ET

Everyday stressors like a report due at work, the refrigerator breaking and the dog throwing up can sometimes make you want to grit your teeth. But layer on top of that a pandemic, economic uncertainty and political upheaval, and you might start to give your jaw a serious workout — gritting and grinding with as much as 250 pounds of force.

Dentists have reported an increase in patients with tooth fractures since the start of the pandemic, which they attribute to bruxism, the technical term for gritting, grinding or clenching your teeth. Thought to be precipitated or exacerbated by stress and anxiety, bruxism is largely subconscious and often occurs during sleep. Most people don’t know they grind their teeth unless a dentist tells them so, based on tooth wear. Less obvious indicators include itchy or plugged ears, neck pain and even premature aging of the face.

Expensive acrylic or rubber mouth or bite guards — often called night guards — are typically prescribed as a prophylactic.

While night guards may help to prevent some dental wear and tear, some studies suggest they can be ineffective or even make the problem worse. This has led some experts in the fields of dentistry, neuroscience, psychology and orthopedics to say there needs to be a paradigm shift in our understanding of the causes and treatment of bruxism. They say it is a behavior, like yawning, belching or sneezing, rather than a disorder.

“It’s not abnormal to brux,” said Frank Lobbezoo, a bruxism researcher and professor and chair of the Academic Center for Dentistry Amsterdam in the Netherlands. “In fact, it can be good for you.”

Sleep studies indicate that the majority of people have three or more bursts of activity in the jaw’s masseter muscle (your major chewing muscle) during the night. It also happens during non-REM sleep. So, contrary to popular belief, you’re not doing it while you are dreaming.

Moreover, the evidence suggests that this muscular activity can have the salubrious effect of opening up your airway to allow in more oxygen. Clenching and grinding also stimulates salivary glands to lubricate a dry mouth and neutralize gastric acid. As a result, experts say it can be dangerous to wear a night guard or splint if you have sleep apnea or severe gastrointestinal reflux disorder, or GERD.

“There’s tremendous overtreatment for a non-problem,” said Karen Raphael, psychologist and professor at New York University College of Dentistry, referring to the widespread use of bite guards, tranquilizers and even Botox injections to prevent bruxism. “There is no evidence that tooth wear patterns reflect current grinding.” Indeed, she said, tooth wear is more often associated with an acidic diet, which both erodes enamel and triggers bruxism to increase the pH in the mouth. Treating bruxism in this instance would be treating the effect rather than the cause.

Of course, an overproduction of stomach acid and reflux often occur during times of stress, which might in part explain why dentists and patients are reporting more cracked teeth and jaw pain since the start of the pandemic. Also, people tend to drink more alcohol when they are anxious. Even mild intoxication leads to more flaccid neck muscles, which can cause an increase in both the duration and force of bruxism to restore airflow.

Other factors that may increase bruxism are poor sleep hygiene and bad posture. If you are a light or poor sleeper, you spend more time in non-REM sleep, which is when people naturally brux. This might be caused by stress, but also consuming caffeine or sleeping with your phone.

And we tend to take our postural habits to bed with us. If you’re tight and clenched when you are awake, you’re likely also tight and clenched when you are asleep, or at least it takes you longer to unwind. This is especially true now as people spend so much time hunched over their devices with head, neck and back forming a taut and orthopedically ill-advised “C.”

So the question is not so much whether you brux, but why you might be bruxing more than is normal and possibly causing jaw or dental problems. “Bruxism is not a disease,” said Giles Lavigne, a neuroscientist, dentist and professor at the University of Montreal. “It’s just a behavior, and like any behavior, when it reaches a level that it’s bothersome you may need to consult someone.”

Perhaps a physical therapist who can teach you how to relax your jaw and do abdominal breathing. And maybe a psychologist can help you modify behaviors that lead to an increase in bruxism, like eating too much before bed and drinking more than your share of wine and whiskey.

But simple awareness of the position of your mouth, tongue and teeth throughout the day may go a long way toward preventing tooth-grinding. “Nobody knows where their tongue is when they are at rest,” said Cheryl Cocca, a physical therapist at Good Shepherd Penn Partners in Lansdale, Pa., who treats patients with bruxism. She recommends continually checking to make sure you are breathing through your nose with your mouth closed, your tongue resting on the roof of your mouth, and your teeth apart. Set a timer if you need to remind yourself or do it every time you stop at a red light or get a text alert.

Part of the problem could be our modern diet. A growing body of evidence supports the once-fringe notion that, following the agricultural and industrial revolutions, as humans began eating foods that are more processed and easier to chew, we came to have smaller jaws than our ancestors and underdeveloped orofacial muscles. A result, researchers say, is that we tend to breathe through our mouths, with our tongues resting on the bottom of our mouths.

“Watch people on subway, watch people on the bus, they’re all on their phones, their mouths are slightly open breathing in and out. Particularly kids, they all are,” said Dr. Tammy Chen, a prosthodontist in New York City who has written about the increase in tooth fractures. “As soon as the mouth is open, the tongue is down. The tongue should always be on top of the mouth pushing up and out,” which strengthens face and neck muscles, widens the jaw and opens the airway.

At night, our modern penchant for soft pillows and mattresses, rather than lying on the ground as our ancestors did, makes our mouths more likely to fall open and for us to drool, leading to a drier, more acidic mouth microbiome, not to mention sagging neck muscles, which further obstruct the airway.

A firm pillow, or a folded blanket under the head, can help, as can committing to an orofacial, neck and airway stretching and strengthening routine. Ms. Cocca recommends daily repetitions of pulling your head back into your neck as if you were trying to retreat from someone leaning in for a kiss and also nodding your head down until your chin touches the base of your throat.

Other good exercises are squeezing your shoulder blades together and holding, as well as putting your arms up like a goal post and leaning into a doorway to stretch out your chest.

Research also indicates diaphragmatic breathing and singing can strengthen and expand your airway muscles to reduce both snoring and bruxism.

While bite guards worn during the day or night won’t stop you from grinding, Dr. Chen said, they can act as a bumper to protect teeth. But only if they are carefully designed according to the size and shape of your mouth, and of materials specific to whether you are a grinder, clencher or chomper. Hard acrylic guards are thought to be better for grinders and chompers while softer rubber guards are better for clenchers. However, experts caution guards can sometimes make the problem worse, particularly if they are poorly made.

“Bruxism often comes down to a breathing or airway issue,” Dr. Chen said. “Night guards are a band aid, but if you want to stop grinding, you have to get to the root cause of the issue.”

Running Is a Total Body Affair

Phys Ed

Running Is a Total Body Affair

We can thank our heads and shoulders — and not just our knees and toes — that we evolved to run as well as we do.

Credit…Edward Muybridge/Getty Images
Gretchen Reynolds

  • Feb. 10, 2021, 5:00 a.m. ET

We can thank early human evolution that many of us can enjoy running as much as we do. Watch anyone with a ponytail run, and you can see their hair repeatedly describe a figure-eight in the air, responding to the forces generated by the running. But their heads stay still, their eyes and gaze level.

If it weren’t for some unique evolutionary advances, our heads would do the same as that ponytail, flopping like a swim noodle when we run, according to a clever new study of how — and why — our upper bodies seem to work the way they do when we run, but not when we walk. The study, which involved treadmills, motion capture, hand weights and an eon’s worth of back story, finds that an unusual coordination between certain muscles in runners’ shoulders and arms helps to keep heads stable and runners upright.

The new findings may answer lingering questions about the role of our upper bodies in running and why we, unthinkingly, bend and swing our arms with each stride. They also add to the mounting evidence that, long ago, distance running began shaping human bodies and lives in ways that still reverberate today.

The possibility that we humans are born to run has inspired many studies, books, lectures and debates in recent years, including the journalist Christopher McDougall’s 2009 best seller, “Born to Run.” The idea is based on fossil research indicating that early humans evolved to have distinctive leg bones and other characteristics that would have aided distance running. The findings suggest that those of our ancestors who could run well dominated in the procuring-food and procreating sweepstakes, so that natural selection started favoring physical characteristics associated with running.

Much of this research came from the mind and laboratory of Daniel Lieberman, a professor of human evolutionary anatomy at Harvard University and author of the new book “Exercised,” which delves into exercise and evolution. At first, most of his and other scientists’ work related to evolution and running centered on lower bodies, since legs play such an obvious part in how we get from one place to another.

But Dr. Lieberman also was interested in runners’ upper bodies and, especially, their heads. As a longtime marathon runner himself, he knew that a stable head is critical for successful running, but not necessarily a simple thing to achieve. Running is propulsive. You push off, rise and then brake forcefully against the ground with every stride, placing forces on your head that could make it flop uncontrollably, like that bobbing ponytail.

How we manage to keep our heads stable, however, has not been altogether clear. Like most cursorial species, or animals that run, including dogs and horses, we have a well-developed nuchal ligament, a tissue that connects the skull and neck. That is not the case in species that aren’t natural runners, like apes or swine.

When he was a young scientist, Dr. Lieberman recalled, he enticed pigs — who are inelegant runners — onto treadmills to study their biomechanics. Their heads jiggled like bobbleheads when they were forced to run, prompting Dr. Lieberman and his colleagues to conclude they lacked a nuchal ligament, a finding borne out by anatomical studies.

But we humans also have the challenge of being upright, on two legs. Presumably to balance ourselves while running, we began, at some point, to swing our arms. Dr. Lieberman guessed that the arm swing helped to stabilize our heads. But, if so, there would have to be coordination between the muscles in our forearms and shoulders, he thought, even though these muscles do not physically connect. They would need to fire together and with comparable force during running, if they were to be successful in stabilizing our heads.

He was uncertain about how to test that theory, though, until his colleague Andrew Yegian, a college fellow in the department of human evolutionary biology at Harvard, suggested weighting runners’ arms and heads. Add mass there, he said, watch how the muscles respond, and you would be able to tell if the arms and shoulders were working together to steady the head or not.

So, for the new study, which was published last month in the American Journal of Physical Anthropology, Dr. Lieberman, Dr. Yegian and their colleagues fitted 13 men and women with sensors on their upper bodies that track muscle activity and asked them to, first, walk and then run on a treadmill while the researchers filmed them with motion-capture technology. Then the scientists handed the volunteers light hand weights and asked them to run again. Finally, they strapped weighted masks to the volunteers’ faces and had them run once more, before comparing how everyone’s muscles had responded to each of these interventions.

It turned out that not much of interest happened while the study volunteers walked; the muscles in their forearms and shoulders showed no evidence of coordinated activity. But those same muscles snapped into synchronized action when the volunteers started to run; the muscles began firing at the same time and with about the same amount of force.

That synchrony grew during the weighted runs. When the volunteers carried weights and their forearm muscles fired with extra force to compensate, the muscles in their shoulders did the same. Similarly, when their weighted faces prompted the runners’ shoulder muscles to fire more forcefully, their arm muscles did likewise.

The study does not explain how these widely separate muscles communicate with one another, though. Nor can the findings pinpoint when, in our existence as a species, they may have started to work together in this way. It also does not prove that all of us are natural born runners; plenty of people do not enjoy the sport.

Still, the results do tell us more than we knew before about our bodies, Dr. Lieberman says, and underscore that running molded us as a species. “If we didn’t have to run” in our early days as humans, he says, “we wouldn’t have this system” of muscular interplay today.