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 or dental caries, or holes in the teeth.
Tooth decay is caused by acid-producing bacteria, especially the Streptococcus mutans (S mutans) bacteria. Decay happens when food is consumed and broken down into small particles. The bacteria in the mouth combine with the food particles and build up to produce a sticky film called dental plaque. The bacteria in dental plaque consume the sugars and starches in the 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 the age of 34. Tooth decay is more likely to affect older adults, and nearly all adults aged 65 and older have had a cavity.
When a cavity is just forming, it may be impossible to detect and only appear in an X-ray. On an X-ray, a cavity may appear as a darker shadow or a hole. When tooth decay is very small and not seen clinically, it may be picked up on an x-ray between the teeth. When a cavity grows and becomes more severe, it will become a darker, larger shadow on the x-ray.
If the cavity is visible, it 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, a process called demineralization.
As a 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, which is why it is essential to practice prevention techniques, such as brushing and flossing twice daily and attending regular dentist visits.
The common signs of tooth decay include:
There are six distinct stages of tooth decay, each more dangerous than the next. The following are the symptoms and signs of each stage:
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. Demineralization can be reversed by maintaining proper at-home oral hygiene like brushing with fluoride toothpaste and flossing.
When the demineralization and remineralization process stops, enamel decay will occur and create a hole or sticky spot in the tooth. When this happens, white spots on a tooth darken to a brownish or yellowish color, sensitivity increases, and cavities form. Cavities must be filled by a dentist to prevent further complications.
When tooth decay progresses past enamel decay, it reaches the dentin, which is the tissue that lies under the enamel. Dentin contains tubes that lead to the tooth's nerves, which makes it more sensitive to acid damage. Because dentin is much softer than enamel, decay advances much quicker when it reaches this stage.
At this stage in the decay process, bacteria reach the pulp, which is the tooth's innermost level that contains nerves and blood vessels. At this stage, tooth decay can cause extreme tooth pain. The bacterial infection, if untreated, may cause an abscess to form.
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 and cause swelling of the gums, face, or jaw, and a fever. An abscess requires immediate treatment to prevent the infection from spreading to the jaw, head, and neck.
If the tooth becomes too compromised from decay and infection, tooth extraction is the only option to prevent further damage.
Here are the standard methods dentists use to treat tooth decay:
Tooth decay can be easily prevented and reversed if caught in the earliest stages. To prevent tooth decay, follow these best practices:
Untreated tooth decay can lead to many uncomfortable physical consequences, including:
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.
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, which contains fluoride.
If tooth decay progresses past demineralization to enamel decay and cavities, it will require professional treatment from a dentist.
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 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5034904/
“Dental Cavities: MedlinePlus Medical Encyclopedia.” MedlinePlus, U.S. National Library of Medicine, https://medlineplus.gov/ency/article/001055.htm
Forssten, Sofia D et al. “Streptococcus mutans, caries and simulation models.” Nutrients vol. 2,3 (2010): 290-8. doi:10.3390/nu2030290. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257652/
“Hidden Dental Dangers That May Threaten Your Whole Body.” Harvard Health, Harvard Medical School, www.health.harvard.edu/staying-healthy/hidden-dental-dangers-that-may-threaten-your-whole-body
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 (2016): 31-33.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6373711/
“Hygiene-Related Diseases.” CDC.gov, Centers for Disease Control and Prevention, 22 Sept. 2016, www.cdc.gov/healthywater/hygiene/disease/dental_caries.html
“Oral Health Conditions.” CDC.gov, Centers for Disease Control and Prevention, 1 May 2020, https://www.cdc.gov/oralhealth/conditions/index.html
“Preventing Tooth Decay.” CDC.gov, Centers for Disease Control and Prevention, 29 May 2015, www.cdc.gov/policy/hst/statestrategies/oralhealth/index.html
“Tooth Decay.” Healthdirect, Healthdirect Australia, Jan. 2019, www.healthdirect.gov.au/tooth-decay
Tooth Decay. Medline Plus. U.S. National Library of Medicine. 2 Oct. 2020, https://medlineplus.gov/toothdecay.html#:~:text=Tooth%20decay%20is%20damage%20to,are%20holes%20in%20your%20teeth.