Is it true that dentists can tell your s*xual history from your mouth? What experts say

A viral tweet has got people talking, and it’s largely down to a commonly held belief: That a dentist can tell if you’ve given oral s*x.

In one such viral tweet, which racked up 2.9 million views, someone wrote: “Hey @grok, my boyfriend went to his best friend’s birthday party three days ago and he got this mark under his mouth. Can you tell me the reason for it?”

The eternally innocent Grok couldn’t diagnose the issue, but it did confirm the presence of petechiae, tiny, pinpoint-sized spots.

Hey @grok , my boyfriend went to his best friend’s birthday party three days ago and he got this mark under his mouth. Can you tell me the reason for it? pic.twitter.com/PZvdi0c4Wy

— Aria (@wydAriaX) May 28, 2026

“It looks like a red circular lesion (possibly petechiae or a small bruise) on the roof of the mouth/palate. Could be from suction/trauma (e.g., vigorous oral activity, hard food/drink, or accidental bite), irritation, or minor infection,” it said.

People had a field day with Grok’s innocence in the comments, with most making oral jokes and telling the woman that: “Your boyfriend has a boyfriend.”

People have claimed as much for years, but what’s the actual truth? Can your dentist really tell if you’ve been freaky over the weekend?

Can dentists actually tell if you’ve given oral?

S*xual activity should, of course, be between those actually involved, which is why the concept of a nosy dentist is terrifying. They’re supposed to be looking for cavities, not taking note of your extracurricular activities.

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Speaking to Vice in 2018, dentist Dr Milad Shadrooh was stunned at the question. He denied the notion, at least concerning his own skills.

“Wow! I don’t know about that. I’ve never been asked this question before! Never in my life have I been able to tell if a patient has done oral sex. I don’t know any dentist who would, either. What a question to ask [laughs],” he said.

Check out how wonderful grok response was. https://t.co/jvdP8uLtuQ

— Jay Daddy (@JayDaddy272661) May 28, 2026

When Vice pushed further, pulling out the bruising at the back of one’s throat, he theorised it could be possible if “they did it literally like two minutes ago in the waiting room.”

But don’t count yourself lucky just yet. Though dentists won’t be able to tell in most cases, there are situations where they could come to that conclusion. Repeated trauma to the back of the throat DOES cause petechiae, as evidenced by four studies found here.

Long story short: It’s a case-by-case sort of situation, so either cancel your next dental appointment or find a safer hobby.

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Featured image credit: Twitter/Canva