What Does A Cavity Look Like?

Updated: Apr 17

Not the most pleasant news to hear when your dentist tells you that you have a cavity. We can picture what is running through your head, "Oh gosh, now I have to come back and get it filled." That we know but do you even know what tooth decay looks like?

Recurrent cavity
Recurrent cavity

Table of Contents

What is a cavity?

The definition of a cavity is a hole. The hole is caused by tooth decay and the culprit happens to be the bacteria in your mouth that is processing all of those sweets you've been eating. Any type of soda, candy, or desserts will do the trick.

Cavities can form anywhere on your teeth. Your tooth has 5 different surfaces so the decay can penetrate the enamel from any combination of those surfaces. If the decay involves all of the surfaces then it will be a big cavity but if it only involves one surface then it is a small cavity.

What does a cavity look like?

Are you curious as to what a cavity looks like? I bet your dentist has never showed you what they even look like. You just know that they exist but have never set your eyes upon them.

Here are some intraoral photos of tooth decay inside the mouth taken at our long island city dental office.

We included photos of the decay on various surfaces of the tooth:

  • Decay on the side

  • Decay on top of the tooth

  • Decay in between the teeth

  • Decay in an existing filling

Hopefully that gives you a good idea of what they look like. The most obvious difference is in the color, the decay is usually brown to black in color. The shade of brown is also indicative of how deep the filling will be. The outermost layers that are the most infected and decayed are a very dark brown but as you clean out the filling more, it gets lighter in color and closer to yellow.

The texture of the decay is also different. When you scratch the enamel of a healthy part of the tooth, it will feel solid. If you scratch at the decayed part with a dental tool, it will actually feel soft and sticky. The best comparison would be a termite infested piece of wood. That wood will not be solid but soft and mushy feeling. The same thing occurs in teeth.

We've included photos below of the cavity removal process:

Aside from the visual appearance, we can also show you what a cavity looks like on an x ray.

Cavity on an x ray
Cavity on an x ray

Do you see one tooth with a dark circle? That is what a cavity looks like on a bitewing x ray. They typically show up as dark areas.

  • Solid structures and materials show up as very white on the radio graph, we call it radiopaque.

  • Structures that are not as solid or air show up as darkness, we call it radiolucent.

When you start seeing darkness inside things that should be white, it is becoming less solid, kind of like Swiss cheese.

Other signs you may have a cavity

A small cavity may be difficult for you to detect on your own and only a dentist may be able to diagnose you but sometimes you may be able to feel one. If you notice any of these symptoms below, you may want to be cautious and get it checked out:

  • Toothache - when you feel pain from eating or maybe even spontaneously.

  • Sensitivity - if your tooth feels changes to temperature or even to sweets.

  • Discoloration or holes in your teeth

  • Swelling or bleeding gums - this could mean that you may have a big hole somewhere

  • Bad breath - if there are a lot of bacteria secreting acid by processing all of the sweets you eat, the chances of you having a cavity in between your teeth are pretty high.

How does teeth decay form?

Cavities require 4 things to form and it won't happen if it is missing one ingredient:

  • Bacteria

  • Sugar

  • Host

  • Time

Basically the bacteria eats the sugar and produces acid as a byproduct. This acid will dissolve the host's enamel but it doesn't happen over night. The acid requires time for it to completely erode the enamel.

It is also important to note that the bacteria work the most effectively and efficiently when the pH of the mouth drops to below 5.5, which is considered the critical pH. The average pH of the oral cavity is around 6.7.

How do you treat cavitites?

The treatment for it would be cavity fillings where we remove the decay first and then fill it back in with a composite resin, which is a tooth colored filling material. The process is as follows:

  1. Apply numbing gel, followed by the dental numbing shot.

  2. Cavity removal by drilling out the decayed parts.

  3. Tooth conditioner to clean it.

  4. Tooth primer to prepare it for bonding.

  5. Apply the tooth bonding.

  6. Fill it in with a composite resin.

  7. Light cure it to make it hard so that it sets.

  8. Adjust it and polish to make the bite even.

If you want a more in depth guide on cavity fillings, please see our guide.

Can you reverse a cavity?

You may be surprised but it is possible to reverse cavities but only small ones. Big ones are usually past the point of reversal. There are two proven ways to reverse tooth decay:

How fluoride can reverse cavities:

  • Fluoride ions will replace the hydroxyl group on hydroxyapatite to become fluorapatite.

  • Fluorapatite is more stable, harder, and more acid resistant than hydroxyapatite.

  • Fluoride can remineralize the decayed parts up to the outermost 30 μm of enamel.

How hydroxyapatite toothpaste can reverse cavities:

  • Adds an additional layer of hydroxyapatite on top of the tooth enamel. Your tooth is made of the same substance so now you have two layers.

  • The toothpaste serves as a reservoir of calcium and phosphate ions, which are the building blocks of tooth remineralization.

  • It also does not preclude the fluoride from working so the underlying enamel layer will get strengthened from residual fluoride in the mouth from drinking sources.

So yes you can reverse them but the cavities won't go away on their own though!


We hope that you now know everything there is to know about what teeth decay looks like and what you should do about it. If you have any questions, please feel free to contact one of our LIC dentists at 1311 Jackson Ave Dental.

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