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What causes a tooth infection? Related conditions and treatments

Medically reviewed by Catherine Chien, DDS
Medical Reviewer
Updated Feb. 27, 2024  •  Published Apr. 17, 2023
Fact Checked
Tooth infection causes

Overview: What does tooth infection feel like?

Bacterial infections of the tooth range in severity from an asymptomatic shallow cavity to severely painful infections of the inner tooth and the structures surrounding a tooth. Technically, healthcare professionals don’t consider teeth infected until bacteria invade the innermost part of the tooth, called the pulp and the root. This inner tooth contains living tissues, blood vessels, and nerves, unlike the outer, hard outer layers of the tooth. However, cavities are also tooth infections, but they don’t involve symptoms or an immune response. Cavities usually feel like nothing, though they often look like dark or discolored holes in the tooth. The tooth might become sensitive to pressure or temperature if they get deep enough. 

On the other hand, when the infection reaches the pulp, that’s when the toothache starts. At first, the tooth hurts when pressed or comes in contact with cold or heat, like eating cold food. When the infection gets worse and spreads to the tooth’s root, the tooth constantly hurts, with a throbbing pain that often worsens at night. Symptoms can worsen when the infection spreads outside the tooth, called a dental abscess.

Key takeaways:

  • Tooth infection is a common dental problem caused by bacteria.

  • Typically, a tooth infection does not require immediate medical attention, but tooth infections can worsen into dental emergencies.

  • Tooth infection generally requires treatment. It typically resolves with treatment immediately, but tooth infections that have spread to other parts of the face or body could take several days or weeks of treatment to get better.

  • Tooth infection treatment may include fillings, root canals, tooth extraction, or antibiotics. 

  • Chronic tooth infections can be managed with good oral hygiene, but a dentist should treat a tooth infection.

  • Use coupons for tooth infection treatments, like sodium fluoride, chlorohexidine (Periogard), and amoxicillin, to save up to 80%.

What causes tooth infection?

Tooth infections are caused by bacteria. Only two species of bacteria cause cavities: Streptococcus mutans and Streptococcus sobrinus. These bacteria produce acid out of sugar, which wears away tooth enamel. 

Normally, the teeth are covered with bacteria colonies. These colonies are mostly harmless, and most are considered beneficial. However, sometimes, the environmental balance on the tooth is thrown off to favor the acid-producing bacteria. The most common cause of this imbalance is sugar in the diet. The acid not only eats away at tooth enamel but also inhibits the growth of some of the “good” bacteria on the teeth. 

Eventually, a cavity forms filled with acid-producing bacteria, a condition called dental caries. These tooth enamel infections eventually gain access to the inner parts of a tooth, the pulp. However, sometimes bacteria get into the pulp through dental procedures or a tooth injury like a cracked tooth. Once in the pulp, the infection has entered living tissue, so it feels more like a regular infection. To fight the infection, the body mounts an inflammatory response. The swelling caused by the immune system produces most of the symptoms of a tooth infection.

Should I be worried about tooth infection?

Are tooth infections something to worry about? Other than the tooth pain? Only a few hundred years ago, tooth infections were a leading cause of death among our ancestors. So, yes, untreated tooth infections can be dangerous for your health. 

Left untreated, a tooth infection could lead to:

  • A tooth abscess (periapical abscess, a pocket of pus that forms below the tooth’s root) 

  • Bone infection of the jaw (osteomyelitis)

  • Soft tissue infection (cellulitis) of the floor of the mouth and the neck (Ludwig’s angina)

  • Throat abscess

  • Infections of the chest area (mediastinitis)

  • Blood clots in the head (cavernous sinus thrombosis)

  • Brain infections

  • Blood infections (bacteremia)

  • Infections of the inner part of the heart (endocarditis)

  • Sepsis

Some of these complications, such as mediastinitis, sepsis, and brain infections, have a high mortality rate.

Schedule an appointment with a dentist if a tooth hurts or the gums are swollen or bleeding. Tooth infections generally do not require emergency treatment unless they spread to other parts of the head or body. However, severe pain or swelling is a sign the infection has spread to living tissue and requires immediate dental care.

How is the cause of tooth infection diagnosed?

A dentist diagnoses and treats tooth infections. 

Radiographs of the teeth will be taken at the beginning of the office visit. The dentist examines the radiographs to determine the location of the infection and whether there are any dental abscesses or other complications. The dentist examines the tooth and may take pictures to show the patient the dental problem. If there’s any worry that the infection has spread to other parts of the body, a CT or MRI scan may be ordered. Blood tests may also be required for more extensive infections.

Is tooth infection contagious?

The bacteria that causes tooth or gum infections can spread between people through saliva. So the answer is yes, cavity-causing bacteria are contagious. However, that doesn’t mean cavities, tooth decay, and tooth infections are contagious. Tooth infections aren’t the result of “catching” a cavity-causing bacterial infection. Instead, they result from an environmental imbalance in the mouth that favors cavity-causing bacteria. The primary cause is sugar in the diet. Poor oral hygiene that allows for plaque buildup contributes to the problem.

How long does a tooth infection last?

For practical purposes, consider every tooth infection a problem that does not go away without treatment. Once a tooth infection develops into a dental abscess, the prognosis worsens if no treatment is sought. 

Depending on the infection, dental work typically resolves the problem. Cavities and pulp infections are typically resolved on the same day with appropriate treatment, such as fillings, decay removal, or a root canal. More severe infections that involve a dental abscess may resolve on the day of the procedure. However, patients often require additional antibiotic treatment for several days to help clear the infection. 

How to stop tooth infection

Treatments for tooth infections start with removing the source of the infection. For surface cavities, the dental treatment consists of fillings. If the infection has reached the pulp and is reversible, treatment consists of removing the decay and restoring the tooth with a filling. If a pulp infection is irreversible, the dentist will perform a root canal or remove the affected tooth. Root canal treatments are usually performed by a dentistry specialist called an endodontist.

Treatment for an abscessed tooth is more complicated. An incision into the abscess, draining the pus, rinsing the wound with salt water, and providing over-the-counter pain relievers like ibuprofen may be all that’s needed for some people. In other cases, a root canal or removal of the infected tooth followed by several days of antibiotics may be required.

If the tooth infection has spread to other parts of the body, antibiotics will be needed to clear the infection. Hospitalization and even intensive care may be required in complicated cases.

RELATED: Antibiotics 101: what are they and why do we need them?

Living with a tooth infection

If tooth infections keep happening, there are a few ways to keep them at bay. Most will involve maintaining oral health through good dental hygiene:

  • Brush your teeth twice daily for two minutes each time with fluoride toothpaste. 

  • Don’t rinse with mouthwash right after brushing.

  • When you rinse, use a mouthwash containing an antiseptic or fluoride—or both.

  • Floss between teeth daily to remove food debris.

  • Replace your toothbrush regularly.

  • Avoid sugary foods.

RELATED: What are carbs? Everything you need to know about carbohydrates

Most importantly, get regular dental checkups

A tooth infection usually does not resolve on its own. It often gets worse and could evolve into a serious or even life-threatening infection somewhere else in the body. The sooner it is treated, the more likely the tooth can be preserved and catastrophic complications avoided. The best advice is to visit a dentist regularly to catch and treat tooth and gum problems early. Regular cleanings and plaque removal by a dental hygienist dramatically reduce the risk of developing cavities and tooth infections.

FAQs about the causes of tooth infection

What causes a tooth infection to spread to the jaw?

The upper teeth are embedded in the skull, and the lower teeth are embedded in the jawbone. When a tooth infection spreads to the soft tissue inside the tooth, it can spread down to its root. From there, the infection can spread to the tissues that hold the tooth in place and eventually reach the bone of the skull or jaw. 

Can smoking cause tooth infection?

Smoking does not cause tooth infection but doubles the gum infection risk called gingivitis. Gingivitis is not a tooth infection but can spread to the periodontal ligament, which holds the tooth in place. Periodontitis is a serious gum infection. Symptoms of periodontitis include severe pain, bad breath, gum swelling, and sometimes fever, especially if it involves a periodontal abscess. From the periodontal ligament, the infection can migrate to the tissue inside the tooth (the pulp). Usually, severe periodontitis loosens the tooth, which can then fall out, a more common problem among smokers. 

Will a high-sugar diet cause tooth infection?

The two species of cavity-causing bacteria need sugar to thrive, grow, and overwhelm other bacteria that don’t cause cavities. Cavity-causing bacteria thrive on lots of types of sugars, but sucrose is the one they thrive on most. Sucrose is common table sugar—the sugar you put in coffee or bake into cakes. One study has shown that a sugar-restricted diet significantly decreases the amount of cavity-causing bacteria in the teeth. The good news is that “artificial sweeteners” made from sugar alcohols like sorbitol, xylitol, and maltitol are fine. Cavity-causing bacteria don’t metabolize them and, in some cases, are toxic to cavity-causing bacteria and decrease their numbers on the teeth.

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What’s next? Additional resources for people with tooth infection

Test and diagnostics

Treatments

Scientific studies and clinical trials

Medically reviewed by Catherine Chien, DDS
Medical Reviewer

Catherine Chien, DDS, received her bachelor's degree in Biochemistry from University of California San Diego, her dental education at UCLA, and her pediatric dental training at the University of Pennsylvania and the Children's Hospital of Philadelphia. Dr. Chien has been practicing in a large group practice for the past 17 years in Oxnard and Ventura, California, where she provides treatment with behavior management, nitrous oxide, oral conscious sedation, and treatment under IV sedation. Dr. Chien is also a Diplomate and Fellow of the American Board of Pediatric Dentistry. She enjoys giving back to her community through volunteering at various community events including dental fairs and events at the local dental society.

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