Product Reviews
Updated on July 19, 2022

Tooth Decay Symptoms, Causes & Treatment

NewMouth is reader supported. We may earn a commission if you purchase something using one of our links. Advertising Disclosure.

What Causes Tooth Decay (Cavities)?

Tooth decay is damage to a tooth’s outer surface or enamel. This happens when bacteria in the mouth produce acids that break down enamel.

Tooth decay leads to cavities (holes in the teeth).

class i cavity

Tooth decay is caused by acid-producing bacteria, especially Streptococcus mutans (S. mutans) bacteria. Decay happens when food is consumed and broken down into small particles.

Bacteria in the mouth combine with food particles and build up to produce a sticky film called dental plaque. The bacteria in dental plaque consume sugars and starches in food particles and produce acid. The acid dissolves the minerals in enamel, causing cavities.

Dental cavities (tooth decay) are widespread. On average, one in five people in the United States has untreated tooth decay.

More than 80% of people will have had at least one cavity before 34.

Tooth decay is more likely to affect older adults, and nearly all adults aged 65 and older have had a cavity.

frowning young man with one hand on cheek

What Does a Cavity Look Like?

When a cavity is just forming, it may be impossible to detect. When tooth decay is minimal, it may be picked up on an x-ray between the teeth.

It may appear as a darker shadow or a hole. When a cavity grows, it will become a darker, larger shadow on the x-ray. 

The cavity will appear as a little white spot on the tooth in its initial stages. This indicates that the tooth is losing essential minerals that keep it strong and healthy. This process is called demineralization.

As the cavity develops, it creates a discolored or dark spot on the tooth. Cavities come in different colors and shades, from white to grey to black and even yellow. They may also appear as a visible pit or hole in the tooth.

Many cavities may not have physical symptoms, so it is essential to practice prevention techniques. These include brushing and flossing twice daily and attending general dentist visits.

Symptoms of Tooth Decay

The common signs of tooth decay include:

  • Bad breath
  • Toothache or tooth pain
  • Increased tooth sensitivity to sweets or hot or cold temperatures
  • Gum disease or swelling or bleeding gums
  • White or discolored stains on the surface of a tooth
  • Visible holes or pits in a tooth
  • A dental abscess which can cause fever, pain, and facial swelling
  • Teeth that are easily chipped or fractured because of weakened enamel

6 Stages of Tooth Decay

There are six distinct stages of tooth decay, each more dangerous than the next. The following are the symptoms and signs of each stage: 

Stage One - Demineralization

Demineralization is when the minerals in the tooth enamel, primarily calcium, decrease. This occurs when acids produced by bacteria eat at the minerals in the outermost layer of the tooth.

Demineralization may cause white spots to appear on the teeth. You may be able to reverse demineralization at home by brushing with fluoride toothpaste and flossing.

Stage Two - Enamel Decay

When demineralization and remineralization stop, enamel decay will occur. This creates a hole or sticky spot in the tooth.

When this happens, white spots darken to a brownish or yellowish color, sensitivity increases, and cavities form. Cavities must be filled by a dentist to prevent further complications.

Stage Three - Dentin Decay

When tooth decay progresses past enamel decay, it reaches the dentin, the tissue that lies under the enamel.

Dentin contains tubes that lead to the tooth's nerves, making it more sensitive to acid damage. Because dentin is much softer than enamel, decay advances much quicker when it reaches this stage.

Stage Four - Pulp Damage

At this stage in the decay process, bacteria reach the pulp, the tooth's innermost level. It contains nerves and blood vessels. At this stage, tooth decay can cause extreme tooth pain.

The bacterial infection, if untreated, may cause a dental abscess to form.

Stage Five - Abscess

When tooth decay advances into the pulp, bacteria invade and cause an infection. The infection causes inflammation that creates an abscess or a pocket of pus at the bottom of the tooth.

An abscess causes:

  • Severe pain that can radiate into the jaw
  • Swelling of the gums, face, or jaw
  • Fever

An abscess requires immediate treatment to prevent the infection from spreading to the jaw, head, and neck.

Stage Six - Tooth Loss

If the tooth becomes too compromised from decay and infection, tooth extraction is the only option to prevent further damage.

Treatment for Tooth Decay

Here are the standard methods dentists use to treat tooth decay:

Silver Diamine Fluoride

This antibacterial varnish contains a higher level of fluoride than traditional treatments. It can be used for very small cavities to help remineralize the lesion. It is used for patients who may not be eligible for a traditional filling. 

Dental Fillings

Fillings are used to treat typical cavities. A dentist removes the decayed tooth tissue and restores the tooth by filling it with a filling material.


A crown is a covering made of gold, porcelain, or metal, used to repair and replace decayed or weakened areas of the tooth. It covers the entire tooth and provides more stability and support for teeth that have more severe tooth decay.

Root Canal

Root canal treatment is used when the nerve in a tooth dies from decay or injury. The pulp and decaying portions of the tooth are removed, and the roots are filled with sealing material. 

Tooth Extraction

The dentist may have to pull your tooth if they can't fix the damage to the pulp.

How to Prevent Tooth Decay

Tooth decay can be easily prevented and reversed if caught in the earliest stages. To prevent tooth decay, follow these best practices:

  • Use an electric toothbrush to brush teeth thoroughly
  • Use enough fluoride by brushing twice a day with an ADA-accredited fluoride toothpaste, drinking tap water with fluoride, and using a fluoride mouth rinse
  • Prevent dry mouth by drinking enough water
  • Always brush before bedtime, when saliva production, which protects teeth, is decreased
  • Flossing daily to remove plaque
  • Limit sugary foods, carbohydrates, and snacking
  • Eat calcium-rich foods
  • Avoid tobacco products
  • Dental office visits twice yearly for regular check-ups and professional cleanings
  • Dental sealants or plastic coatings are applied by dentists to prevent cavities from forming on the chewing surfaces on back teeth or molars

What Happens if Tooth Decay is Left Untreated?

Untreated tooth decay can lead to many uncomfortable physical consequences, including:

  • Discomfort or pain
  • Increased sensitivity
  • Fractured tooth
  • Infection or abscess
  • Shifting of teeth
  • Gum disease
  • Tooth loss

These physical symptoms negatively impact lifestyle and cause problems with speaking, eating, working, and playing. In extreme cases, tooth decay may lead to death when an infection travels from the tooth to the brain.

Can I Remove Tooth Decay Myself?

This earliest stage of tooth decay, demineralization, can be reversed before permanent damage occurs. Using fluoride, which strengthens enamel, can reverse demineralization. Fluoride treatments include fluoride mouthwash, fluoride toothpaste, and drinking tap water that contains fluoride.

If tooth decay progresses past demineralization to enamel decay and cavities, it will require professional treatment from a dentist.

10 Sources Cited
Last updated on July 19, 2022
All NewMouth content is medically reviewed and fact-checked by a licensed dentist or orthodontist to ensure the information is factual, current, and relevant.

We have strict sourcing guidelines and only cite from current scientific research, such as scholarly articles, dentistry textbooks, government agencies, and medical journals. This also includes information provided by the American Dental Association (ADA), the American Association of Orthodontics (AAO), and the American Academy of Pediatrics (AAP).
  1. Abou Neel, Ensanya Ali et al. “Demineralization-remineralization dynamics in teeth and bone.” International journal of nanomedicine vol. 11 4743-4763. 19 Sep. 2016, doi:10.2147/IJN.S107624
  2. “Dental Cavities: MedlinePlus Medical Encyclopedia.” MedlinePlus, U.S. National Library of Medicine,
  3. Forssten, Sofia D et al. “Streptococcus mutans, caries and simulation models.” Nutrients vol. 2,3 : 290-8. doi:10.3390/nu2030290.
  4. “Hidden Dental Dangers That May Threaten Your Whole Body.” Harvard Health, Harvard Medical School,
  5. Heng, Christine. “Tooth Decay Is the Most Prevalent Disease.” Federal practitioner : for the health care professionals of the VA, DoD, and PHS vol. 33,10 : 31-33.
  6. “Hygiene-Related Diseases.”, Centers for Disease Control and Prevention, 22 Sept. 2016,
  7. “Oral Health Conditions.”, Centers for Disease Control and Prevention, 1 May 2020,
  8. “Preventing Tooth Decay.”, Centers for Disease Control and Prevention, 29 May 2015,
  9. “Tooth Decay.” Healthdirect, Healthdirect Australia, Jan. 2019,
  10. Tooth Decay. Medline Plus. U.S. National Library of Medicine. 2 Oct. 2020,,are%20holes%20in%20your%20teeth.
linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram