Tooth Decay: Stages, Complications, and Treatment

Tooth decay occurs when bacteria in the mouth produce acids that attack the enamel, or protective outer layer of the tooth. If left untreated, tooth decay could lead to gum disease, cavities, and possibly tooth loss. 

Unfortunately, tooth decay is very prevalent in the United States. According to the Centers for Disease Control and Prevention (CDC), more than 1 in 4 adults have untreated tooth decay. Knowing the signs and symptoms of tooth decay can lead to treatment to restore healthy teeth and gums. It’s also crucial to learn how to maintain good oral hygiene to ward off tooth decay. 

This article will discuss the causes and risk factors of tooth decay, signs and symptoms, stages, and how tooth decay is treated.

A dental tooth decay cavity as seen in a dental mirror

Image by JHLee

Tooth Decay Stages

Tooth decay doesn’t happen immediately. Instead, it occurs over time in a series of stages due to poor oral hygiene.

Stage 1: White Spots of Demineralization in Enamel

As acids break down the tooth’s enamel, white spots may start to appear on the tooth as a result of the minerals lost in the process. If the enamel is repaired at this point, the white spots could disappear as the tooth regains lost minerals.

Stage 2: Cavity Formation and Enamel Decay

If the tooth enamel is not repaired when white spots start to appear, it could continue to weaken as the mineral loss increases. At this point, a cavity could start to form. Initially, it could appear as a light brown spot on the tooth. If not treated, a hole will develop in the tooth. Once the cavity is formed, it cannot be reversed, only repaired by inserting a filling.

Stage 3: Dentin Decay

Underneath the enamel, the dentin covers the pulp at the center of the tooth. Because it’s softer than enamel, dentin typically decays much faster than enamel does. Once tooth decay moves into the dentin, it’s important to get treatment right away or the tooth decay will move into the center of the tooth.

Stage 4: Damage to Pulp

Inside the tooth is soft tissue containing nerves and blood vessels; this is called the pulp. Once tooth decay spreads to the pulp, it is likely that it will require root canal treatment. The patient may be referred to a specialist known as an endodontist to receive this treatment.

Stage 5: Infection, Abscess, and Gum Disease

Once tooth decay reaches the pulp, it evolves into a full infection that affects the nerves and blood vessels in the tooth and can move into the jawbone and other teeth. This could lead to an abscess, or a pus pocket. If not treated, the tooth could die.

Tooth Decay Symptoms

Tooth decay symptoms include: 

  • Toothache; pain can range from mild to severe
  • Sensitivity to hot or cold foods or beverages
  • Sensitivity to sweets
  • White or brown spots on the tooth
  • Cavities
  • Infection or abscess
  • Bad breath
  • Bad taste in your mouth

When to See a Dentist

If you are in between regular dental check-ups and notice any signs of tooth decay or start to experience any tooth decay symptoms, you should schedule an appointment with your dentist for an exam. The sooner your dentist can identify any signs of tooth decay, the sooner you can start treatment, which can prevent more serious tooth decay in the future. 


During a dental exam, your dentist will look for any white or brown spots on the tooth as well as any soft or sticky areas that indicate weakened enamel. If necessary, your dentist also may take an X-ray to look for areas of tooth decay that may not be readily apparent. 

Causes and Risk Factors

There are a number of causes and risk factors that could lead to tooth decay.

  • Location of teeth: Teeth located in the rear of the mouth may be more susceptible to tooth decay because they are hard to reach when brushing and flossing. 
  • Diet: A diet rich in sugar and starch can lead to more tooth decay because the bacteria in tooth plaque use these to make the acids that can eat away at tooth enamel. 
  • Frequency of eating and drinking: If you eat or drink often throughout the day, the tooth enamel on your teeth does not have time to recover from acid attacks that lead to lost minerals. 
  • Feeding infants at night: If you put your baby down at night with a bottle, there’s a higher risk of the formula or breast milk lingering in the mouth on the teeth. The longer it lingers on the teeth, the more opportunity for acids to form and attack the tooth enamel.
  • Dry mouth: Saliva plays an important role in removing the bacteria in the mouth that leads to acids attacking tooth enamel. If you don’t have enough saliva to prevent dry mouth, you are at a higher risk for tooth decay because you have more bacteria in the mouth. 
  • Poor oral hygiene: Brushing and flossing teeth twice a day goes a long way in removing bacteria, plaque, and acids that could lead to tooth decay. This includes brushing and flossing correctly so the tooth surface is thoroughly cleaned, and flossing is able to remove all food particles between teeth and along the gum line.
  • Age: As we age, our teeth experience more wear and tear, which could lead to tooth decay. Also, if you have receding gums, the teeth are more exposed to bacteria and acids that lead to tooth decay. 
  • Insufficient fluoride: Fluoride, a mineral that builds up resistance to acid, is necessary to help protect the tooth enamel from acid attacks that lead to tooth decay. If you are not getting enough fluoride through such efforts as brushing twice a day with fluoride toothpaste, your teeth are more susceptible to tooth decay. 
  • Eating disorders: Proper nutrition is key to building strong, healthy teeth and gums. If you aren’t receiving the nutrients needed for good oral health due to an eating disorder, you could develop tooth decay. Also, frequent vomiting exposes teeth to stomach acids that can damage tooth enamel, leading to tooth decay. 
  • Heartburn and GERD: Acids produced by heartburn or GERD, a digestive disorder wherein stomach acids move back up into the mouth, can move into the mouth and over the teeth. This can harm the enamel, resulting in tooth decay. 
  • Old, worn, or broken dental work: Over time, fillings could break down, with acids and bacteria leaking into cracks around those fillings.


Treatment for tooth decay varies based on how far the tooth decay has progressed. Treatments include:

  • Fluoride treatments: If you are in the early stages of tooth decay, your dentist could recommend fluoride treatments to help fight off acid and restore and protect the enamel. 
  • Filling cavities: If the tooth decay has evolved into a hole in the tooth (a cavity), your dentist will need to remove any decayed tissue in the tooth and replace it with a filling.
  • Dental crowns: If the tooth decay has progressed beyond a cavity and is affecting the interior of the tooth—the dentin and possibly the pulp—your dentist will remove all tissue affected by the tooth decay and cover the tooth with a crown, a cap that replicates the tooth’s appearance. 
  • Root canal: Once tooth decay spreads to the pulp, an endodontist will need to go inside the tooth to remove all tooth decay and infection in the nerves and blood vessels. Once the decay is gone and the tooth is healed from the infection, your dentist likely will cover the tooth with a crown. 
  • Treat infection, possible tooth extraction: If the tooth is beyond repair, your dentist likely will remove it and replace it with an artificial tooth

Outlook and Prevention

If tooth decay is treated early, it can prevent serious oral hygiene problems. Taking steps to prevent tooth decay is the best defense for protecting your teeth. 


In most cases, tooth decay can be readily treated. Of course, the earlier it is diagnosed and treated, the better for preventing more serious complications of tooth decay. 


There are a number of options for preventing tooth decay:

  • Brush twice a day with fluoride toothpaste. Drinking fluorinated water and using a fluoride mouth rinse also can help prevent tooth decay. 
  • Floss your teeth at least twice a day. 
  • Limit sugary and starchy foods, and don’t snack or drink a lot between meals. 
  • Don’t use tobacco products
  • See your dentist for regular check-ups and dental cleanings. 


Tooth decay occurs when bacteria and acids attack the tooth’s enamel and could lead to more serious dental problems if not treated early on. Many factors can contribute to tooth decay, such as the location of the teeth, diet, age, eating disorders, heartburn, general oral hygiene, and more. Symptoms of tooth decay include tooth sensitivity, pain or discomfort, white or brown spots on the teeth, and bad breath.

There are many treatments for tooth decay, which vary based on how far the decay has progressed. They can range from fluoride treatments to removal of the tooth.

A Word From Verywell 

Oral hygiene often gets overlooked, but it’s an important part of our overall health. As such, taking care of your teeth and gums is necessary in order to avoid tooth decay. Brushing teeth twice a day with fluoride toothpaste, flossing regularly, and eating a healthy diet can help keep teeth healthy.

If you have any concerns that you have may have tooth decay, schedule an appointment with your dentist as soon as possible for an exam. The earlier tooth decay is diagnosed, the easier it is to treat.  

Frequently Asked Questions

  • Can tooth decay go back to normal?

    Yes, you can reverse tooth decay with proper and timely treatment.

  • How do dentists remove decay?

    It depends on how severe the tooth decay is. The early stages could be treated with dental cleaning and fluoride treatments. As it progresses, you may need a dental filling, root canal, or extraction to fully eliminate tooth decay.

  • How can I remove tooth decay myself?

    If you are in the early stages of tooth decay, you can brush twice a day with fluoride toothpaste and use a fluoride mouth rinse to help remove tooth decay and rebuild tooth enamel.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Ctvrtlik R, Tomastik C. Tooth wear - fundamental mechanisms and diagnosis. IOSR Journal of Dental and Medical Sciences. 2016;15(5):84-91. doi:10.9790/0853-1505088491

  3. MedlinePlus. Tooth decay.

  4. American Dental Association. Baby bottle tooth decay. MouthHealthy.

  5. Marchesan JT, Byrd KM, Moss K, et al. Flossing is associated with improved oral health in older adults. J Dent Res. 2020;99(9):1047-1053. doi:10.1177/0022034520916151

  6. National Eating Disorders Association. Dental complications of eating disorders.

  7. American Dental Association. Fluoride.

  8. American Dental Association. Decay. MouthHealthy.

By Karon Warren
Karon Warren has been a freelance writer for more than two decades, covering a range of lifestyle and business topics for print and online lifestyle and consumer publications.