What does a cavity look like?

What does a cavity look like

A cavity is an area of decay in the tooth. Plaque build-up, excessive sugar in the diet, and less salivary flow contribute to cavity formation. Tooth decay goes through various stages and appears in various forms in different individuals depending on the stage at which it is spotted. In this article, I will discuss how different stages of a cavity look like and what symptoms are telltale signs of a cavity in a tooth. 

The whole article is divided under the following headings:

  • What causes a cavity in your mouth?
  • What does a tooth decay look like?
  • What does a surface cavity look like?
  • What does a small cavity look like?
  • What does a deep cavity look like?
  • What to do if you see any of the signs and symptoms of cavity?
  • What does a cavity look like on an X-ray?
  • Why are some teeth prone to cavities?

What causes a cavity in your mouth?

The following conditions favor tooth decay in the teeth, and the presence of more than one factors results in rapid decay of several teeth at a time. 

  • Poor oral hygiene
  • Excessive consumption of foods that cling to your teeth for a long time, such as chocolates, biscuits, cakes, etc. 
  • Frequent snacking or sipping beverages
  • Lack of fluoride in drinking water and food
  • Dry mouth
  • Worn fillings 
  • Eating disorders like anorexia and bulimia

What does a cavity look like? 

The following are the warning signs of a cavity:

Black or brown spot on a tooth 

Black or brown discoloration of a tooth may be a sign that you have a cavity. However, it needs to be differentiated from tooth staining, which is common among smokers and habitual coffee drinkers. Some iron or copper-rich foods may also cause staining of teeth. 

You may notice a black or brown discoloration in the pits and grooves of the tooth in a cavity. On the contrary, generalized discoloration of teeth often indicates teeth staining. 

Broken-down tooth or hole in a tooth

A hole in a tooth can result from an advanced cavity in a tooth. One or more tooth walls can be lost due to tooth decay. 

The decay-causing bacteria weakens and destroys the tooth from the inside; its outer enamel loses its support and falls apart, making a hole in the tooth.

What does the inside of a cavity look like?

A broken down decaying tooth shows a black discoloration from the inside. Food often gets trapped into the hole and if not removed, it rots giving rise to rotten egg smell. This particular smell is produced due to formation of hydrogen sulphide by the bacteria in the decaying tooth.

Swelling of the jaw 

Swelling of the jaw is also a sign of tooth abscess and a deep cavity in a tooth. The tooth infection is initially confined to the tooth. However, if left untreated, it spreads in the surrounding bone causing swelling of the jaw.

You will see jaw swelling close to the decaying tooth. 

Gum boil or pimple 

The spreading cavity infection may also manifest as a boil or pimple above the tooth’s root on the gums.

If you notice a gum boil, your tooth may have decayed and needs immediate treatment. You may also experience an occasional pus discharge from the boil. 


What does a cavity feel like? A pain in the tooth is the most common symptoms of a cavity. A cavity can trigger different intensities of pain.

Cavity pain is often triggered by eating and drinking sweet, hot, or cold drinks. The pain is relieved once the stimulus is removed. This is usually a sign of dentinal (second layer of the tooth) decay and is treated by placing a dental filling in the tooth after removing the decay.

You may also experience spontaneous episodes of severe pain. This type of pain suggests nerve involvement in the teeth and requires a root canal treatment. 

The pain may also be felt on one side of the jaw, making it hard to recognize the problematic tooth. All these pain symptoms call for a dental check-up to evaluate their cause and early treatment. 

A delay in seeing a dentist allows time for further tooth destruction, which will eventually require more aggressive treatment, costing you a fortune.

Tooth Sensitivity

Sensitivity in the tooth can be one of the symptoms of tooth decay. Sensitivity to hot and cold foods and drinks alone is not the best cavity indicator. However, it is most commonly linked to exposure of dentin or roots to the oral environment. 

Difficulty in mouth opening 

A tooth infection in the third molar can cause soreness in the muscle of mastication, leading to difficulty in mouth opening. The reduced mouth opening makes your eating difficult.

Bad breath 

A carious (decayed) broken-down teeth allows food to get trapped in the tooth and provides breeding ground for bacterial growth. The bacterial products and rotten entrapped food are a major cause of bad breath in people with cavities.  

A bad smell from your mouth, if you’re taking good care of oral hygiene, can be due to a cavity in the mouth. 

What does an early cavity look like (a surface cavity)?

In the begining, a cavity looks as a dull white opacity on the tooth. White spot forms due to the loss of minerals from the tooth enamel. 

Tooth decay is prevalent in people who consume a lot of sugar and sodas. The oral bacteria efficiently metabolize sugars in the diet into organic acids. The acid dissolves the mineral from your teeth. Such frequent episodes lead to demineralized white spots on the teeth. 

These white demineralized areas can stain and turn into dark brown or black spots. At this stage, tooth decay is reversible.

Click on the link for full article on, Is tooth decay reversible?

What does a small cavity look like?

A small cavity looks as black spots or a small hole on the tooth. At this stage, the decay has extended into the superfical layers of the dentin and can be easily resored by a composite or amalgam filling after removal of tooth decay.

What does a bad cavity look like (a Deep cavity)?

As the bacteria advances into dentin, the cavity progresses relatively faster. The dentin is softer and less mineralized than enamel. The bacteria destroy the dentin by producing enzymes that dissolve its minerals and disintegrate the organic matrix.

As tooth decay approaches near the pulp, one or more tooth walls break away due to dentinal destruction forming a large hole in the tooth.  

An advanced cavity appear as a large hole in the tooth accompanied by severe pain. However, in some situations, the pulp tissue dies, making the tooth painless.

What to do if you see any of the signs and symptoms of cavity?

Yes, it is essential to see a dentist if you spot two or more of the above signs and symptoms. Early intervention allows removal of tooth decay in its early stages, saving both your tooth and money. 

Advanced decay involving tooth’s nerves may require an extraction or a root canal therapy.

The root canal therapy and crown are two to three-visit treatments and can cost you an arm and a leg if you don’t have a private dental insurance.

Click the link for full article on, When is a tooth beyond saving.

What does a cavity look like on an X-ray?

On an x-ray, you will see different opacities of different layers of the teeth. The radio-density of the tooth layers decreases from outside to inside. Radio-dense structures appear white, while the radiolucent ones appear black on an X-ray. 

The layers of the teeth appear white on the x-rays with a decrease in opacity as you look into the deeper layers.

The enamel is the most mineral-dense tissue of the body and reflects radiations and appears white on an x-ray. The dentin appears less white than enamel.

The pulp (core of the tooth) lacks minerals and is composed of blood vessels, nerves and reparative cells. Therefore, it is seen black on an x-ray.

The areas appearing black on the enamel and dentin shows a cavity. They appear black because of the mineral loss from that area. 

Click the link for a detailed article on, How do dentists find cavities.

what does a cavity look like
The arrow points towards a cavity on the tooth on an x-ray.

Why are some teeth prone to cavities?

There are two main types of teeth in adults, front and back. These teeth differ in shape, size, and structure, which allows them to perform specific functions. 

Let’s see how cavities affect different teeth in the mouth.  

A Cavity on the back tooth

Three molars and two premolars are broad teeth in the back of your mouth on each jaw side. Among them, the first or 6th-year molars are the permanent teeth that erupt at age six and are most likely to develop tooth decay due to their early eruption.

The chewing surface of the molars has pits and groves of varying depths and is most prone to cavities. These areas are difficult to clean with a toothbrush allowing plaque to accumulate. 

What does a cavity look like
The broken down molar shows a cavity.

The surfaces between the two teeth are also likely to develop tooth decay because the tight contacts between the teeth allow food and plaque deposition. These surfaces require regular flossing to clean the entrapped food and plaque deposits.  

What does a cavity look like between teeth? A cavity between the teeth is difficult to spot at home unless the surface breaks away, leaving a hole in the tooth. Dentists use an explorer and X-rays to diagnose them.  

What does a cavity look like on a molar? On the biting surface of a molar, you may see a black spot at the initial stages or weakened broken down tooth in advanced tooth decay. 

A Cavity on the front tooth 

Cavities are less frequent in adult front teeth because of their smooth self-cleaning surfaces. Additionally, tooth decay on the front teeth has declined since the beginining of water fluoridation in drinking water. 

However, you may get a cavity between teeth in the front teeth, or near gums, especially if you have receding gums. 

What does a forming cavity look like on a front tooth? You will see a black spot near gums, but a black spot doesn’t always indicate a cavity. It could be a calculus or staining on the tooth. Staining often involves more than one tooth and calculus is seen a hard yellowish deposit firmly clinging to the tooth.

Front teeth are less likely to develop dental caries or cavities because the salivary flow frequently washes away the food debris. 

What does a cavity look like
A brown discoloration on the canine next to gums shows a cavity.

Click the link for full article on, 5 Reasons to get a cavity in front tooth and ways to fix it.

A Cavity on the baby tooth 

Baby teeth are small with thin enamel and large pulp chambers and are likely to get a cavity if plaque build-up and dietary sugars are not controlled.

The children put to bed with a milk bottle often develop cavities in front teeth. The teeth bathe in the milk, and the mouth bacteria demineralize them and initiate the process of tooth decay. Interproximal surfaces (surfaces two adjacent teeth) show black spots on their surface. 

What does a rotting tooth look like on a baby tooth? Baby teeth get black discoloration near gum margins or between the teeth in the front teeth. The chewing surfaces of baby molars develops holes and becomes painful early on because of pulp horns extenting up in the tooth.


What can be mistaken for a cavity? 

The following problems can be mistaken for a cavity:

  • Tooth staining 
  • Vertical fracture in the tooth 
  • A crack in the tooth
  • Myofascial pain, such as trigeminal neuralgia 

Does a cavity go away on its own?

No, a cavity doesn’t go away on its own. By maintaining good oral hygiene, the progression of a cavity can be slowed, but the destruction that has occurred is an irreversible process and requires a filling or root canal. 

Can a cavity go away with brushing?

Brushing can’t cure a cavity. However, it may delay the rate of its progression. Tooth decay restricted to enamel can be halted by regular brushing and controlling refined sugar in the diet. Brushing with fluoridated toothpaste and flossing are essential tools to prevent cavities. Also, tooth decay in the dentin requires a filling.

Does a cavity hurt?

A moderate or deep size cavity causes pain. The intensity of pain increases with the increase in depth of the cavity. Sometimes, the vital pulp dies due to tooth decay, and the tooth becomes dead and non-responsive to any stimuli. 

How do you confirm a cavity?

The signs and symptoms of the cavities described above help you recognize a cavity. If you have two or more of the above signs and symptoms, you probably have a cavity. You can’t see a cavity in the upper molars properly, so it is difficult to confirm all the cavities at home. Moreover, how a cavity looks and feels varies, so a dentist best confirms a cavity. They use special dental instruments, x-rays, and other specific tests help to diagnose a cavity. 

Can cavities be misdiagnosed?

Yes, a cavity can be misdiagnosed, but the chances of wrong diagnosis are rare. A dental cavity is the most common disease seen in the dental practice, and dentists are specially trained in diagnosing it. Moreover, your chief complaint about the tooth, use of dental explorer and dental X-rays make diagnosis easier and decrease the chances of making an error. 

Why does my dentist say I have a cavity, but I have no pain?

It is not necessary to have pain in the tooth when you have a cavity. There are specific scenarios where you don’t feel pain in the decaying tooth:

  • A small or superficial cavity in the tooth.
  • A deep cavity where the tooth pulp (tooth nerves) dies.

Can a dentist fill a cavity wrong?

Cavity filling is a simple and the most frequently done procedure at the clinic. Errors in filling a cavity wrong by a trained dentist are uncommon.

In developing countries, quackery is common practice. Dental hygienists have opened practices and successfully run their clinics in low-income communities. Fillings errors are common when treated by these unprofessional folks. So please ensure you go to a reputable dental practice with a team of trained dental professionals. 

Why do I have a cavity even though I brush my teeth?

People with good oral hygiene often don’t get cavities. However, you can get a cavity if: 

  • Don’t floss. Floss cleanses the spaces between the teeth and prevents tooth decay between the teeth. A regular toothbrush can’t reach the spaces between the teeth. 
  • The back surface of the last molar is often neglected and often gets cavities. 
  • You keep your teeth clean but eat a diet rich in refined sugars. Refined sugars feed the cavity-causing bacteria and can prone you to cavities, especially between the teeth where food can easily lodge and escapes toothbrushing. 
  • Proper brushing technique is essential for complete plaque elimination. Please ensure you brush the outer, inner, and chewing surfaces of the teeth several times with a toothbrush. The inner surfaces of the teeth are often neglected, so don’t miss them. 
  • Don’t go to bed without brushing your teeth. If the teeth are not brushed before bedtime, the decreased salivary flow during sleep increases bacterial multiplication, increasing the chances of tooth decay. 

Should I brush over my cavity?

Yes, you should. Brushing and keeping the area will not allow food particles to accumulate and cause bad breath. Early cavities that are restricted to enamel don’t progress if kept clean.  

How long can you leave a cavity untreated?

It would be best if you got the cavity treatment asap. An untreated cavity will progress more profoundly in the tooth and cause you pain and more discomfort. It will also increase the cost of treatment. The deeper cavities cause severe pain, often requiring root canals costing a fortune. 

Every cavity progresses at a different rate. Some progress rapidly and involve the tooth nerves within weeks to a few months. Some take longer, so get an appointment with your dentist and get it treated. 

Can you feel a cavity with your tongue?

Yes, you feel a cavity with your tongue. A tactile sensation of the tongue is often required in upper molars, which aren’t visible in the mirror. You can feel a hole in the tooth or shape edge of the broken down tooth with a tongue. 

How do you know if a cavity has been filled wrong?

Major or minor problems can be seen after a filling. If you feel the following features in your filling, you may need to revisit your dentist to fix them:

Rough fillings

Your filling may feel rough if not polished enough. Rough fillings attract more plaque and can initiate the process of tooth decay. This is a minor problem and requires the polishing of a filling.

High fillings

The fillings are shaped according to the tooth’s shape. Your dentist will check high points with an articulating paper and trim them. You will also be asked if the filling is high at the end of the procedure. If the filling feels high when you get back home, you can go to the dentist and get it fixed. 

Feel pain or swelling in the filled tooth

If you experience severe pain or swelling after the filling, you need to go back and get the filling out asap. Often a cavity is deep, but the patient’s symptoms and X-ray findings don’t match to reach a diagnosis.

These cases show success in 50- 60% of the cases when treated with a filling. In these cases, the dentist informs you that the cavity is deep and the filling may or may not work for this cavity. However, if you are willing, he can give it a try and you will be asked to come back if the tooth becomes painful.

No placement of wedge and matrix band

When a filling is placed between the two teeth, a wedge, and a matrix band are placed to keep the filling from bonding to the adjacent tooth.

In some malpractices, the wedge and matrix band are not placed, and the filling is allowed to bond with the adjacent tooth to increase its retention. However, it goes against nature as it prevents the physiological tooth movement between the teeth and favors plaque deposition.

Does the dentist judge you for having cavities?

No, the dentist won’t judge you for having cavities. It is their profession to treat patients and they are there to help their patients help you. They see patients with cavities all the time. They will give you the best treatment and advise you to prevent further tooth decay.


A cavity appear differently in separate individuals. How a tooth decay and cavity look like depends upon the stage at which it diagnosed. 

It appearance of tooth decay ranges from a white dull spot to a hole in the tooth. Every stage of a cavity is treated differently. The initial or enamel caries are reversible, however, dentinal caries and deeper infection require a filling or a root canal treatment.

For more info on how many teeth can be filled at once, click here.

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