Wait, Are Cavities and Gum Disease Contagious Through Kissing?

No need to swear off kissing entirely, but you'll definitely want to read this before your next makeout sesh with a new partner.

two femme-presenting people bumping noses
Photo: Getty Images

When it comes to hookup behaviors, kissing probably seems low-risk compared to ~activities~ such as oral or penetrative sex. But here's some kind of scary news: Cavities and gum disease (or at least, what causes them) might be contagious. So, if you're making out with someone who isn't the best at oral hygiene or who hasn't been to the dentist in a few years, there's a chance you could contract bacteria that can cause some not-so-hot health issues.

"The simple act of kissing can transfer up to 80 million bacteria between partners," says Nehi Ogbevoen, D.D.S., a board-certified orthodontist based in Orange County, California. "Kissing someone with poor dental hygiene and more 'bad' bacteria can put their partners at more risk for gum disease and cavities, especially if the partner also has poor dental hygiene," he explains.

Gross, right? Fortunately, your internal alarm might go off before this even happens. "The reason you usually aren't excited about kissing partners with foul-smelling breath is because, biologically, you know bad-smelling breath is associated with the replication of 'bad' bacteria that could harm your oral health," points out Ogbevoen.

Before you freak out, keep reading. Here's what you need to know about whether dental issues such as cavities are contagious, and what you can do about it.

What Types of Dental Diseases Are Contagious?

So what are you on the lookout for, exactly? Cavities aren't the only thing that might spread — and it all comes down to bacteria, viruses, and fungi, all of which can be passed through saliva, notes board-certified periodontist and implant surgeon Yvette Carrillo, D.D.S.

Also note: Making out with someone whose pearly whites are a tad contaminated isn't the only way you can transfer these diseases. "Sharing utensils or toothbrushes with someone with periodontal disease can [also] introduce new bacteria to your oral environment," says general and cosmetic dentist Sienna Palmer, D.D.S., based in Orange County, California. And be mindful of straws and oral sex as well, as those can both introduce new bacteria, too, says Tina Saw, D.D.S., creator of Oral Genome (an at-home dental wellness test) and general and cosmetic dentist based in Carlsbad, California.


"Cavities are caused by a specific series of 'bad bacteria' that go unchecked," notes Saw. This specific type of bad bacteria "produces acid, which breaks down the enamel of the teeth," she says. And, yep, this bacteria can actually be transferred from person to person and can wreak havoc on your smile and oral health, even if you have excellent oral hygiene. So, with respect to the whole, "are cavities contagious?" question, the answer is…yeah, kind of.

Periodontal Disease (aka Gum Disease or Periodontitis)

Periodontal disease, also known as gum disease or periodontitis, is inflammation and infection that destroys the supporting tissues of the teeth, such as the gums, periodontal ligaments, and bone — and it's irreversible, says Carrillo. "This is caused by a combination of the body's immune system trying to fight off bacterial infection and the bacteria themselves," she explains.

This aggressive disease comes from bacteria, which can come from poor oral hygiene — but it's a different type of bacteria from the ones that cause cavities, explains Saw. Instead of wearing away at the enamel, this type goes for the gum and bone, and can cause "severe tooth loss," she says.

While periodontal disease itself is not transmissible (because it's so dependent on the host's immune response), the bacteria that causes it is, says Carrillo. This, friends, is where you run into trouble. These bad bacteria (such as in the case with cavities) can "jump ship" and "transfer from one host to another via saliva," she says.

But don't worry too much: Even if this bacteria does end up in your mouth, you won't automatically develop periodontal disease. "In order to develop periodontal disease, you must have periodontal pockets, which are spaces between the gum tissue and the root of the tooth caused by an inflammatory response," explains Palmer. This inflammatory response happens when you have a buildup of plaque (the sticky film that coats teeth from eating or drinking and can be removed by brushing) and calculus (aka tartar, when plaque isn't removed from teeth and hardens), she says.

Ongoing inflammation and irritation of the gums eventually cause deep pockets in the soft tissue at the root of the tooth. Everyone has these pockets in their mouth, but in a healthy mouth, the pocket depth is usually between 1 and 3 millimeters, whereas pockets deeper than 4 millimeters may indicate periodontitis, according to the Mayo Clinic. These pockets can fill with plaque, tartar, and bacteria, and become infected. If not treated, these deep infections can ultimately cause a loss of tissue, teeth, and bone.

And as if irreversible bone damage and tooth loss weren't enough to freak you out, periodontal disease has also been linked to "other inflammatory conditions like diabetes, heart disease, lung disease, and Alzheimer's," says Carillo.


This one is reversible, says Carrillo — but it's still not fun. Gingivitis is inflammation of the gums and is the beginning of periodontal disease."The inflammation causing gingivitis leads to bleeding gums," says Carillo. "So, both the bacteria or blood can be passed through saliva when kissing... Just imagine billions of bacteria swimming from one mouth to the other!" she adds. (Proceeds to vom.)

How Easy Is It to Transmit These Diseases?

"It's surprisingly common, especially when dating new partners," says Carrillo. Her team "often gets patients in the office with sudden gum tissue breakdown, who have not had issues before," she shares. At this point, she will review any sort of new changes in a patient's routine — including new partners — to root out what may have introduced "a new microbiota that the patient didn't have before as a normal part of their oral biome," explains Carrillo.

That said, you don't need to panic if you recently swapped spit with someone new, notes Palmer. "Kissing someone with poor dental hygiene does not necessarily mean you will develop similar symptoms," she says.

"Luckily, cavities and gum disease are not diseases that we can 'catch' from our partners," says Ogbevoen. It comes down to the "bad" bacteria from the other person, and said bacteria "must be able to multiply to actually infect our gums or teeth," he says. "As long as you brush and floss as recommended by your dentist to prevent 'bad' bacteria from growing, you shouldn't have to worry about 'catching' gum disease or cavities from your partner," explains Ogbevoen.

The absolute worst-case scenario is tooth loss, but while it's possible, it is also extremely unlikely, says Ogbevoen. "The odds you could lose a tooth from kissing someone with poor dental hygiene are essentially zero," he says. In most scenarios, proper dental hygiene will mitigate any infection, especially if you're on top of your dental visits assures Ogbevoen.

Who's Most at Risk?

Everyone's level of risk here is different. "Everyone's oral environment is unique, and you may have tight, healthy gum tissue, smoother tooth surfaces, less root exposure, shallow grooves, or more saliva, which would decrease your chance of developing oral diseases," says Palmer.

But the experts share that certain groups are more vulnerable targets for this icky transmission — namely immunocompromised individuals since the inflammation associated with periodontal disease strains the immune system and makes it less effective at fighting infection, says Saw.

Again, partners of individuals who have poor dental hygiene (for whatever reason) are also prone to possibly receive the bad, possibly aggressive, bacteria — so make sure you are not that partner! "A clean oral environment is important for you and your loved ones to prevent the transfer of disease-causing bacteria from person to person," says Saw.

And while, yes, this article's focus is the concept of transmission via making out, it's worth noting that there's another highly vulnerable group: babies. "Before you have babies, make sure your cavities are fixed and your oral health is good because bacteria can transfer to the baby," says Saw. A combination of kissing, feeding, and the parent's microbiome can all transfer bacteria both during birth and afterward. This goes for anyone doing the caretaking or giving a baby some smooches, "so make sure everyone in the family is on top of oral hygiene," recommends Saw.

Signs You Might Have a Dental Health Issue

Worried you may have an issue on your hands? Signs of gingivitis and periodontal disease include red swollen gums, bleeding when brushing or flossing, and bad breath, says Palmer. "If you notice any of these warning signs, visiting a dentist or periodontist [a dentist specializing in the prevention, diagnosis, and treatment of periodontal disease] for a thorough exam and cleaning is the best way to prevent disease progression," she suggests. Meanwhile, cavities may come with symptoms such as toothache; tooth sensitivity; visible holes or pits in your teeth; staining on any surface of a tooth; pain when you bite down; or pain when eating or drinking something sweet, hot, or cold, according to the Mayo Clinic.

FYI, you may not develop symptoms right away or immediately after exposure. "Everyone develops decay at different rates; factors like oral hygiene, diet, and genetic predisposition can all affect the rate of decay," explains Palmer. "Dentists can detect changes in the development of cavities and periodontal disease in six-month intervals, which is why dentists recommend a check-up exam and cleaning at least two times a year," she adds. (Also read: What Is a Dental Deep Cleaning?)

What to Do About Contagious Dental Issues

Hopefully, you're feeling motivated to brush your teeth by now. Good news: This is your number-one defense against all of this transmission.

If You're Worried About "Catching" Something

If you know you are, or think you might be, a victim of a "PDH make-out" (Palmer's acronym for poor dental hygiene), regular and diligent brushing, flossing, and rinsing — aka practicing good dental hygiene — is your first move, as it will kill or remove most disease-causing bacteria, recommends Palmer.

"Prevention is key," says Carrillo. "Any changes can trigger gingivitis, or turn gingivitis into full-blown periodontitis," she notes. This means you need to be proactive, too. "Things like changes in medication, changes in stress levels or inability to cope with stress, and changes in diet all need to be communicated with your oral healthcare provider; routine cleanings three to four times a year is advisable for most patients, and daily routines like flossing once a day and brushing at least twice a day is also recommended," explains Carillo.

Asking "do you floss?" mid-date might seem a bit much, but of course, you can always ask your partner about their dental hygiene habits prior to diving in — the same way you would ask whether someone has been recently STD tested before getting intimate.

If You're Worried About Transferring Something

If you're worried that you may be putting someone at risk, this same hygiene plan works for preventing that transmission, too, says Ogbevoen. "With healthy gums and teeth, you can rest assured when you go in for that big smooch you will have great smelling breath and won't be putting your partner at any additional risk for developing gum disease or cavities," he says.

Note: While you want to eradicate bad bacteria, you still need some good bacteria. "We don't want a sterile mouth," says Carillo. "Some mouthwashes clean out everything — it's like antibiotics; if you're on them for too long, it wipes out your good flora that balances your body," she explains. Look for ingredients such as xylitol, erythritol, and other sugar alcohols that are "good for your mouth," and "chlorhexidine," which is good to use "on occasion, not every day," recommends Carillo.

Be Mindful of Mental Health

Talking to a partner about their oral hygiene can be a touchy subject. "If your partner is dealing with gum disease, [you can] help motivate them to be proactive about their oral health, as studies show that with motivation and education, patients can really turn their oral health around," says Carillo.

Before saying something, you should also consider any factors, especially mental health challenges, that may contribute to poor oral hygiene. There's a huge link between depression and periodontal disease, as well as tooth loss, according to research — although it remains unclear exactly why. One theory, according to a study published in the journal Medicine, is that psychosocial conditions might alter the body's immune response and thus predispose people to periodontal disease.

"I see this in my practice all the time," says Saw. "Mental health, specifically depression — especially with COVID — [can cause] hygiene slips, especially oral hygiene," she notes. With that in mind, be kind — whether that's to a partner, or to yourself.

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