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16 Things Your Dentist Can Tell From Just Looking At Your Mouth

Updated: Sep 26, 2023

Cavities and plaque build up are two things that they look for but they can know much more than that from just looking into your mouth. After all, the mouth is the window to the rest of the body. Whatever you eat and make a part of you has to go through the oral cavity first.

Mind blown
Mind blown

What can a dentist tell from just examining your mouth:

The only time you flossed since your last check up was right before this appointment.

Yes, our long island city dentists can tell if today was the only time you've ever flossed since the last time we saw you. You might have walked thinking that you can have us fooled but let me tell you...

inflamed gums
inflamed gums

You can't reverse 6 months of no flossing by just flossing one time. Once we start the dental cleaning, your gums will snitch on you. If you haven't been flossing, your gums will start bleeding and a lot at that. Healthy gums are not swollen and red looking. They also don't bleed easily. In order to keep them healing, you need to be consistent with keeping them clean and it takes more than just one day.

As soon as your dentist sees blood from just touching your gums, the verdict has already been decided. You've either gingivitis or periodontitis, one of the two forms of gum disease.

You snore at night time

Ho Ho Ho, bet you didn't know that did you!? How can your dentist tell that you snore? Well, its really quite simple, we just need to look at your tongue. From the shape of your tongue, we can predict with probably 80-90% accuracy whether you have sleep apnea.

teeth marks on side of tongue
teeth marks on side of tongue

If you snore at night, your tongue will usually have some indentations on the side. This is because you're not getting enough oxygen while you're sleeping so you actively push your tongue up against the sides of your teeth so that you can get more air. In the process you will snore.

Whether you're stressed out while you sleep

We can tell if you're stressed even while asleep. People who are stressed out will have TMJ pain or problems. It will manifest as either bruxism or teeth clenching.

worn down teeth from grinding
worn down teeth from grinding

Some people like to punch holes in the wall to take out their stress and others like to take it out on their teeth. There is a subset of individuals who will grind their teeth at night or just clench as an outlet for stress release.

Yes, the teeth grinding will damage your teeth so you should schedule a consultation to have a night guard made so that it can protect your teeth. You don't want to have worn down looking teeth.

You sucked your thumb as a child

If you had this childhood habit, there may still be a residual sign today. The most noticeable attribute would be an open bite. Your front teeth on the upper may not be touching the lower teeth. It looks as if you are permanently trying to blow a whistle.

open bite
open bite

It is never too late to see an orthodontist for some braces or even invisalign. Either orthodontic treatment can either completely close the bite or at the very least improve upon what you currently have.

You're pregnant

When women are pregnant, their hormones go out of control and one of consequences is that they develop pregnancy gingivitis. This form of gum disease is similar to gingivitis but it just occurs during pregnancy. It is actually their body that is overreacting to the plaque and tartar build up on the teeth. They will experience a lot more bleeding gums and swollen gums.

Sometimes it can even get to the point where they develop a pregnancy tumor. Don't worry it is not an actual tumor. Ladies need to be a little bit more diligent with their oral hygiene during this stressful period. Brushing and flossing more frequently would definitely help counteract all of those extra meals that they're probably having!

You have a nail biting habit

This is an easy one because your dentist actually looks at more than just your mouth. They will oftentimes look at your arms and your hands during the appointment. The reason they do this is two fold:

  • To check if you are nervous because if you are, you would most likely be fidgeting your hands or white knuckling. That is dental anxiety or dental phobia happening.

  • We are mandated reporters for child and domestic abuse. Just to make sure you don't have unexplainable scars!

Last but not least, if you do bite your nails you most likely have damaged enamel and chipped teeth here and there all over your mouth.

You might have GERD

Patients with gastroesophageal reflux disease will typically come in with enamel erosion. More specifically it would be the back part of the tooth that is affected. We refer to this as the tongue side or lingual side of your teeth. The enamel on the tongue side would be all eroded from the acid that is constantly coming up.

You have an eating disorder

This one is similar to GERD because you will show up with enamel erosion as well. The difference this time is that the eroded enamel is on the cheek side or the facial side as we call it.

enamel erosion
enamel erosion

The appearance of this will be pretty similar to biting into lemons and lime. Drinking lemon water daily probably won't erode your enamel though.

You've a sinus infection

Our LIC dentists diagnose sinus infections all that time. We typically do this as a process of elimination because most patients will come in complaining about tooth pain. They will have a toothache that is somewhere on the back upper teeth but they won't be able to pinpoint where the teeth sensitivity is coming from.

As a process of elimination, we can rule out the teeth causing you pain and then the only thing that would be left would be the sinus.

Another way to tell is to bend your head over and start shaking it like a L'Oreal commercial. If you feel pressure or pain, it is probably your sinus. The treatment is fairly simple as it just involves a week of antibiotics.

You've an ear infection

This one is super interesting because some patients come in with face numbness! They won't be able to feel one side of their face as if they just had an injection with novocaine even though they didn't get any dental treatment done. Not a cavity filling nor even a root canal. Their face is just numb and they have no explanation.

It turns out that your facial nerve is quite close to your ear canal so if you have an ear infection, the inflammation and swelling could be pressing on your nerve. This could cause your face to feel like it is going numb.

You have a vitamin deficiency

Do you get canker sores a lot all around your mouth? On your tongue or on your lips? If you get them frequently, you could be deficient in one of the B vitamins.

canker sore on lip
canker sore on lip

Have you heard of scurvy? If you don't get enough vitamin C, you can get scurvy. This affects your gums as well as your tongue. You can have spontaneously bleeding gums.

You've a metabolic disease like diabetes

Your dentist can tell if you have diabetes. You'd be more prone to gum disease and your healing will usually be delayed. This means that if you have any type of oral surgery procedure like a tooth removal, the time it would take for your gums and your bone to heal would be slower than normal. The follow up visits after an extraction will confirm our suspicions.

You've an autoimmune disease

Wow, dentists can diagnosis autoimmune diseases?! Well sort of is the answer. HIV will have oral manifestations. Commonly you can find mouth sores.

Aside from that, there are times where we find that you may have swollen and bleeding gums that are inconsistent with the amount of plaque and tartar on your teeth. Your gums will bleed a lot even though you come regularly for your 6 month teeth cleanings. You also don't seem to have very much calculus build up.

Usually you would require those 3 things for you to have gum inflammation, which we can diagnose you as plaque induced gingivitis but in this case, we are unsure. For these situations, we would refer you to your primary care physician for genetic testing.

You've a drinking problem

Patients who have alcoholic tendencies or are just plain alcoholics, will be cavity prone. They will come in with dry mouth a lot as well. When you have xerostomia, dry mouth, it will increase your chances for tooth decay because saliva acts as a pH buffer that brings it back up. Cavities only form when the pH goes into the acidic range, namely below 5.5

You have cancer

You've heard of oral cancer right? Typical presentation is on the side of the tongue but it can occur anywhere in the mouth.

  • Will typically look like a sore but one that doesn't go away

  • About 50,000 people in the US get it every year.

  • 70% of those affected are men

Risk factors for developing oral cancer:

  • Smoking and that includes smokeless tobacco such as snuff.

  • Excessive alcohol consumption.

  • Family history of cancer.

  • Excessive sun exposure with tanning habits.

  • HPV - human papilloma virus from sexual activity

You love eating sweet foods and drinking carbonated beverages

Now this is a classic because we can tell right away by how many cavities you have! The more tooth fillings you need, the more sweets you've probably consuming. You can't escape the eyes of a dentist if you're addicted to sugary sweets.


Your dentist can get a lot of information about you, just from simply looking in your mouth. Some of these things you may be aware of but others you may not have been. This is why it is important to get a dental check up with your dentist every 6 months. We may be able to catch some things that you don't even know about! The x-rays also give a lot of unseen information as well.



David Chen 200 x 200.jpg

About the author: Dr David Chen, DDS

Hello, I'm Dr Chen and I'm an actively practicing dentist in Long Island City, NY. I graduated from Columbia University College of Dental Medicine in 2016 but prior to going to dental school I was already working in the dental field. It's been more than a decade since I first got to know dentistry and let me tell you, time flies by quickly. Since then I've developed a fondness for writing, which is how this all got started!

Association Memberships:

Medical Disclaimer:

This blog is purely meant for information purposes and should not be used as medical advice. Each situation in your mouth is unique and complex. It is not possible to give advice nor diagnose any oral conditions based on text nor virtual consultations. The best thing to do is to go in person to see your dentist for an examination and consultation so that you can receive the best care possible.

The purpose of all of this oral health information is to encourage you to see your dentist and to inform you of what you may expect during your visit. Due to the unfortunate nature of dentistry, there isn't really any true home remedies that will get rid of dental problems. Roughly 99.99% of them require in-person intervention by a healthcare professional.

Hint: That is the reason why you can't eliminate seeing dentists in your life!

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