Dentists know things about us. They know when we've been eating shit, they know when we've been smoking and they know when we've been avoiding going to the dentist because we absolutely know how many fillings we're going to need and absolutely do not want to get them, so instead just let our teeth erode away, slowly, like the Welsh coastline, inside our faces.

But how much can dentists tell about our actual lives? What can be gleaned? Can they tell if we've been doing drugs? A since-deleted viral tweet, posted earlier this week by a woman billing herself as a dental hygienist, claimed that dentists can tell if someone has recently performed oral sex on a man, because a few little red dots pop up at the back of their throat.

This may sound like an urban myth perpetuated by Yahoo Answers, but it does also sound like maybe it could be true? Stranger things have happened. In December, 2012, a monkey was found traversing an IKEA car park wearing a shearling coat. Elon Musk recently launched a Tesla into space just because.

There’s only one way to know for sure. To address these fears, I decided to call a dentist. Actually, my first suggestion was to suck some dick and then go to the dentist and find out for myself, but my editor decided that a phone call would suffice. So, instead, I spoke to Dr Milad Shadrooh, AKA The Singing Dentist, who shot to Good Morning Britain levels of fame for turning bangers into memorable lessons on dental hygiene and uploading them to YouTube, and who kindly took a few minutes to answer my horrible questions about the oral realm.

VICE: Right, so, firstly, there’s a sort of urban myth going around that dentists can tell whether or not a patient has performed oral sex recently. Is that true?

Dr Milad Shadrooh: 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].

Apparently it’s something to do with some red dots that show up on the back of your mouth?

I have no idea how… unless they did it literally like two minutes ago in the waiting room, then you might smell it? That’s quite disgusting.

What about kissing? Can you tell if someone has done a lot of kissing? Does kissing affect your oral health?

Well, you’ve got to have good oral health to get a smooch! If you’ve got a grubby mouth, that’s no good. Obviously there’s a transfer of bacteria during kissing, so if someone’s got an unhealthy mouth the bacteria might transfer. But the main thing, I think, with kissing – or any sexual activity with the mouth – is Herpes Simplex Virus; cold sores, basically. If you’ve got an active cold sore and you start kissing people – even before it comes up, during the tingle phase – it’s contagious. So you'll pass on the cold sore virus to someone and they’ll become a sufferer. Also, if you were to perform any other activities with your mouth then you can actually pass oral herpes onto the downstairs herpes, so that’s something you need to be very careful of. We would always advocate safe sexual practises for oral sex.

When you type in "can a dentist tell if" into Google, the most common searches are "can a dentist tell if you smoke, vape or do cocaine". Smoking seems like an obvious one, but what about the others?

I haven’t experienced any tell-tale signs of vaping yet, but the jury’s still out on that one. We don’t know too much about vaping because it’s quite new, but there’s new studies coming out that indicate it’s just as bad as smoking, for your mouth, because of the temperatures. The temperatures go up and the capillaries in the mouth still respond the same kind of way as they would if you were smoking. There’s still more research going on, and obviously things take years to happen – you’d need to look at people who have been vaping for the past five years to find out what happened to them after five years, after ten years, and vaping just hasn’t been around that long.

What else can you tell about us from our disgusting mouths?

The stuff that springs out in my mind is grinding. There’s telltale signs in the mouth when a patient has been grinding their teeth, and stress is a number one trigger for grinding. The world is quite a stressful place nowadays, and you can pretty much tell that. There’s food and dietary deficiencies that we can sometimes pick up with the mouth, especially on the tongue. The tongue can have certain appearances that can allude us to certain vitamin deficiencies, potentially iron deficiencies. You can tell if someone has a sweet tooth, because they have a mouth full of holes and fillings.