Jessica Sasaki* never had real tooth problems. Sure, she had braces for a few years when she was a teen, but that's all. For years she went to one of those clinics in Manhattan for her yearly checkup with what she calls a "rotating cast of characters"—"You see the dentist there for like three minutes, they'd say, 'Oh, looks good, bite for me, great' then they'd leave," she says.
In 2013, the dentist noticed signs that Sasaki was grinding or clenching her teeth at night, so she prescribed her an expensive mouthguard. It was hard and covered the front teeth but separated the molars so that they wouldn't grind. She dutifully wore it every night for four years. Sasaki would come in for cleanings every six months, more often when she got pregnant (yes, pregnancy changes even your gums), and the only thing the dentist or hygienist ever said to her was that she might not be flossing enough.
Then Sasaki moved, so she started going to a new dentist, a clinic in Long Island City, Queens. They did an incredibly thorough intake, she says—bite x-rays, Panorex to get a full view of the upper and lower jaws, the works. By this point she had started to notice that something in her mouth felt a little off. "I had given birth and in the process of breastfeeding, I was holding my neck and jaw in weird ways," Sasaki says. "And I thought, my bite feels a little funny."
Her new dentist informed her that she had developed an open bite, where the molars come together in the back but the front teeth don't close—Sasaki says that when a dentist checks her bite, now they can see inside her mouth. That would account for the periodontal issue her last dentist was concerned about, her new dentist said. And over time, having an open bite like that can wear down the enamel of all sorts of teeth, but especially molars.
She visited an oral surgeon before her friend suggested what ended up being the true culprit: her mouthguard. She brought it to an oral surgeon and a specialist in temporomandibular joint (TMJ) syndrome, which is often behind tooth grinding. They corroborated the mouthguard story: "It's definitely that," she recalls one of them saying. "That mouthguard is the devil."
"In my opinion, most appliances should cover all the teeth in the arch so there's no change," says Steven Syrop, a professor of dentistry at Weill Cornell Medical College. Syrop also has a private dental practice in which he specializes in treating facial pain and snoring problems. He treated Sasaki, and while he's unable to comment on her specific case because of patient confidentiality, he says that he sees many hundreds of cases like hers every year. "If teeth are not in contact with opposing teeth, they elevate out of the bone until they meet." That means that over time a front plate mouthguard can cause the molars to rise, leaving the front teeth open and resulting in an open bite.
Matthew Messina, a dentist in Fairview Park, Ohio and spokesperson for the American Dental Association, has never seen a case like Sasaki's. It's rare to see these types of changes just from a nighttime mouthguard, he says, but it can happen. "We like to think our teeth are set in stone, but the body remodels bone. That's why braces work—if we push on teeth, we can move them. It's like slow mud." People with teeth that aren't well supported, weakened by things like gum disease, might find that they move more easily.
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Sasaki's is a rare case, but it begs the question: If a guard like the one she was prescribed can mess up even a few people's mouths, why are they allowed to be sold? One reason is that devices like mouthguards are submitted for premarket approval from the Food and Drug Administration, where they have to show that the it's at least as safe and effective as a comparable product already on the market. The devices are cleared, not approved, says Stephanie Caccomo, an FDA spokesperson, which is presumably a slightly less in-depth vetting process. Occasionally products are further scrutinized—a mouthguard designed to help people stop grinding their teeth, for example, was allowed by a panel convened in 2005 to keep selling over the counter.
The agency keeps a database of all the adverse events (ones that are reported, at least) associated with medications and devices, and a search for mouthguards reveals two cases like Sasaki's filed to the FDA since 2007. Both were due to most often from an over-the-counter nighttime mouthguard called The Doctor's Nightguard (that's not what Suzuki says she used, but it's also a hard nighttime mouthguard), and there are likely others that have not been reported. If the FDA receives enough complaints about adverse events to warrant investigation, Caccomo says, the agency will send out "communications" to patients and health professionals "to ensure proper use of devices and the health and safety of patients." That can sometimes come in the form of a warning about proper use or even a product recall. The FDA has not issued any safety or recall communications about mouthguards, Caccomo says.
Tooth grinding isn't normal, Messina emphasizes. But only a small number of patients need a mouthguard to treat these conditions, Syrop says—other options to prevent pain and other grinding-related issues include medication and a simple bite plate to protect teeth from mechanical damage. Mouthguards should rarely be worn 24/7 and should always be checked by a dentist, especially if patients are using them over the course of months or years. Syrop also suggests that patients shouldn't use mouthguards that only cover the front teeth because of the tendency of the back teeth to rise.
So it's possible for teeth to shift as a side effect of mouthguard use. Dentists should mention that whenever they prescribe a mouthguard, Syrop says. Sometimes dentists prescribe a mouthguard to change the bite on purpose if it's messed up, but a good dentist will be monitoring that to make sure nothing unintended is going on. Depending on the severity of the damage, sometimes all you need is to toss the offending mouthguard—surgery is sometimes necessary, but it's rare.
In cases like Sasaki's, however, it's too late for that: "[I'll] have to pay some thousands of dollars to realign my mouth," she says. She just had a baby, and says she'll have to wait until she's more financially secure. For now, she has a soft plastic mouthguard that she wears at night to protect her tooth enamel, which she admits she uses with some trepidation. "The plan at the moment is go with that for a while and see how I feel about shelling out more."
*Source prefers to use a pseudonym. Her real name is known by Tonic_._
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