Newswise — Let’s say you’re eating a tuna salad sandwich, and when you bite down, you break a tooth. But it was so soft! you think. How could that have happened?

The damage, says Tufts University prosthodontist Gabriela Lagreca, likely began years ago, and was hastened when COVID arrived and stress and worry set teeth on edge—literally. Dentists in the early days of the pandemic began to observe a significant increase in the number of people grinding and clenching their teeth. Two years of pressure, and those weakened teeth can no longer hold it together.

“We are seeing the consequences of 2020,” says Lagreca, an assistant professor at Tufts University School of Dental Medicine and president of the American College of Prosthodontics’ Massachusetts section.

Dentists responding to a poll from the American Dental Association in late 2021 reported a 63% increase in patients with chipped or cracked teeth, compared to before the pandemic.

In her part-time faculty practice, Lagreca estimates that she sees at least three broken-tooth emergencies a week. “I was already prescribing mouth guards for a lot of patients, and now I’m prescribing them more than ever,” she says.

So after two years of clenching and grinding—known in the dental world as “bruxism”—why was that tuna sandwich the last straw?

“The reality is that teeth are like glass,” Lagreca says. Imagine a pebble hitting your windshield. You might not see a crack develop until days later, and then it starts to spread. “That’s exactly what’s happening with teeth,” she says. “We don’t necessarily see the changes right away, when the harm Is happening. But progressively over time, the tooth gets weaker and these cracks travel.”

Here's a clenching and grinding FAQ:

Do clenching and grinding happen only at night?

Daytime clenching and grinding aren’t at all unusual. “You’d be surprised. I clench myself, and I clench out of concentration,” Lagreca says.  A tell-tale sign of a clenching history is that the main chewing muscles become enlarged. “I always ask the patients to do this exercise: Hold your hands to the side of your face, on your cheeks. Clench your jaw and do some clenching and grinding. You shouldn’t be able to feel your hands being pushed out as you do that.” If you feel the muscles “pumping,” you’ve likely been clenching, day or night.

What can a dentist do to help?

The first-line defense is usually a mouth guard, which doesn’t stop the clenching and grinding as much as try to mitigate the damage by spreading the mechanical stress more evenly over the whole jaw. Other treatments can include Botox therapy to relax and weaken the jaw and facial muscles. If dentists see cracks developing throughout a tooth, they may suggest a crown—a cap cemented over a tooth—to protect it before it can splinter or break.

If I break a tooth, or I’m concerned about cracks, should I go to my general dentist or to a specialist?

Prosthodontists are dentists who specialize in restorations—procedures and devices, such as crowns, to replace or protect teeth. There is a lot of overlap between prosthodontics and general dentistry, Lagreca says. If you damage a tooth and you feel comfortable with your general dentist, “go to your general dentist first to get an assessment of the condition,” she says. The general dentist may be able to treat the tooth or may refer you to a prosthodontist or another specialist, depending on the type of damage.

Are over-the-counter (OTC) mouth guards OK?

Lagreca sometimes suggests OTC mouth guards to patients who can’t spare the money or time to get a custom-made mouth guard. “I never recommend them for a permanent solution,” she says. There are significant differences between a drugstore mouth guard and one made by a dentist. The first is the material: A rigid professional mouth guard will last much longer, and will protect against pressure better than the soft gummy plastic of the OTC mouth guards. The other is fit: OTC mouth guards come in a uniform U-shape, “but not everybody’s arch looks like a U-shape,” Lagreca says.

Once you start clenching and grinding, is it possible to stop?

Lagreca says she has sometimes seen patients whose clenching and grinding habits subsided after a change in their life that deflated their stress, and who were eventually able to stop using mouth guards. But that’s something that can only be judged over several years, she says. So pandemic-era bruxers may be in for more of the daily grind.