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What causes an abscessed tooth? Diagnosis, prevention, and treatment

Medically reviewed by Catherine Chien, DDS
Medical Reviewer
Updated Feb. 27, 2024  •  Published Jun. 15, 2023
Fact Checked
Abscess tooth causes

Overview: What is a tooth abscess?

A dental abscess occurs when oral tissue breaks open and forms a pocket that is invaded by bacteria. The body responds by sending white blood cells into that space to destroy the bacteria. Eventually, the pocket fills with bacteria, white blood cells, dead white blood cells, and liquified dead tissue—in other words, a pocket of pus. 

An untreated abscess can infect surrounding tissues or can travel through the bloodstream and cause bacteremia, a serious health issue. A tooth abscess (also called a dental abscess) occurs when a bacterial infection inside a tooth gradually works its way down the center of the tooth, a painful dental health condition called pulpitis. The bacteria reach the bottom of the tooth roots where they can then attack tissues outside the tooth, forming a pocket of pus at the bottom of the tooth. Tooth decay, cavities, and broken teeth all can cause dental infections that can develop into abscesses.

Key takeaways:

  • A tooth abscess is a common health condition that affects any age, sex, race, or ethnicity. 

  • A tooth abscess is caused by bacterial infections of the teeth due to cavities, tooth injury, periodontal disease, or an unsuccessful root canal procedure.

  • Risk factors for tooth abscess include poor oral hygiene, a high sugar diet, smoking, vaping, dry mouth, teeth grinding, and a weakened immune system.

  • Signs of a tooth abscess include a pimple, boil, or fistula near the affected tooth. 

  • Symptoms of a tooth abscess include toothache, tooth sensitivity, severe pain, redness, swelling of the gums, swelling of the face (or cheek, throat, or neck), loose tooth, bad breath, and swollen lymph nodes. If the abscess ruptures, it can cause a foul smell as well as a bad taste, bitter taste, or metallic taste in the mouth. Severe cases of dental abscesses may include difficulty breathing, trouble swallowing, fever, and mental alterations.

  • A tooth abscess requires a diagnosis from a medical or dental professional.

  • A tooth abscess generally does require treatment. It typically resolves with treatment or antibiotics in two weeks or less.

  • Abscesses do not resolve spontaneously. They require treatment:incision and drainage, oral or intravenous antibiotics, root canal, or tooth extraction. Read more about dental abscess treatments here.

  • Prevent an abscessed tooth with good oral hygiene, cessation of smoking or vaping, regular dental care, seeing a dentist for tooth injuries, and reducing sugar intake. 

  • Use coupons for tooth abscess treatments, like Augmentin (amoxicillin-pot clavulanate), Flagyl (metronidazole), and Motrin (ibuprofen), to save up to 80%.

What causes a tooth abscess?

Bacterial infections of the tooth are the cause of the tooth abscess. These infections can be due to:

  • Cavities 

  • Cracked, chipped, or broken teeth

  • Unsuccessful root canal procedures

  • Periodontal issue

Risk factors for an abscessed tooth

The most obvious risk factors for dental abscess are related to poor oral hygiene:

  • Infrequent flossing or brushing

  • Infrequent dental care or dental cleaning

  • Leaving tooth injuries such as cracks or breaks untreated

  • Leaving untreated caries

Other risk factors for developing a tooth abscess include:

  • A high-sugar diet

  • Smoking

  • Methamphetamine use

  • Teeth grinding

  • Weakened immune system

Is a tooth abscess serious? When to see a doctor

Because the bacteria from an abscessed tooth can spread to surrounding tissues (like the jawbone, skull bone, face, neck, head, eyes, and brain), a dental professional or healthcare professional should evaluate and treat the abscess as soon as possible. The earliest sign of a tooth abscess is typically a pimple or a painful lump on the gums near the affected tooth. Throbbing pain is a common early symptom. 

A tooth abscess is a dental emergency if systemic symptoms such as fever, difficulty breathing, difficulty swallowing, or mental changes occur. In those cases, go to an emergency room. If the swelling progresses to the eye or under the chin, seek medical help immediately. 

How is an abscessed tooth diagnosed?

An abscessed tooth is typically diagnosed with a physical examination of the mouth, neck, and head. Sometimes an X-ray is performed. The healthcare professional will ask about risk factors, symptoms, and dental hygiene practices. During the physical exam, the clinician will assess for redness, tenderness, and swelling. The dentist will look at the entire mouth and carefully evaluate the area that is painful and swollen. 

A definitive diagnosis is made with a clinical exam and a radiograph. The neck l will be checked to make sure the infection has not spread and the airway is clear. The clinician may also order a CT scan (as it shows soft tissue infections better than X-rays) to see if the infection has spread to other parts of the head or neck.

Is an abscessed tooth contagious? 

Although a tooth abscess is caused by bacteria, it is not contagious. The bacteria that cause a tooth abscess are commonly found in nearly everyone’s mouth. Even so, do not share dental care devices such as toothbrushes and floss with other people even if no one has a tooth infection or tooth abscess.

Is a tooth abscess curable?

Tooth abscesses are easily treatable. However, if the abscess goes untreated and the infection spreads, treatment is more difficult. 

The standard treatment for tooth abscesses are antibiotics and either incision and drainage, extraction, or a root canal. For an incision and drainage, a dentist, emergency medicine physician, or endodontist will cut into the abscess to release the pent-up pus and insert a drainage tube. It may take several days for the abscess to drain. Some people may need to remain in a hospital during this time. During the recovery period, patients are typically requested to regularly rinse their mouths with warm salt water to help with bleeding, promote healing, and inhibit bacterial growth.

Antibiotics treat localized or systemic infections. Penicillins, cephalosporins, metronidazole, and clindamycin are the most commonly prescribed. To manage pain or discomfort, the clinician may suggest taking over-the-counter NSAIDs or acetaminophen.

When the infection is under control, the clinician will next try to remove the source of the infection. Most dental abscesses are caused by tooth infections that spread out the base of the tooth. To get rid of this infection, a dentist or dental surgeon will perform a root canal or remove the infected tooth. A root canal involves a dentist or endodontist removing the top of the tooth, clearing away dead tissue and bacteria from inside the tooth, cleaning and filling the roots, and then restoring the tooth. Root canal treatment can save the tooth and has a high success rate.

How to prevent an abscessed tooth

The best prevention for dental abscesses is to maintain good oral health:

  • Brush your teeth at least twice per day with a fluoride toothpaste. 

  • Floss your teeth at least once per day. 

  • See a dentist at least once per year for regular dental checkups. 

  • Have your teeth professionally cleaned every six months.

  • See a dentist if a tooth is cracked, broken, or chipped.

  • Avoid sugary foods.

  • Avoid smoking or vaping. 

  • If you have dry mouth, ask a healthcare provider about ways to improve the condition.

Most importantly, see a dentist if you experience symptoms of a dental abscess

Although it may feel like a pimple on the gums at first, a dental abscess can evolve into a serious or even life-threatening bacterial infection. Have a dentist look at the problem if symptoms of a tooth abscess are experienced. The problem can be fixed quickly and the tooth saved if treatment begins early.

FAQs about tooth abscess causes

What are the first signs of sepsis from a tooth abscess?

Sepsis is a possible and potentially life-threatening complication of a tooth abscess. Sepsis happens when the body overreacts to a bacterial infection and starts damaging healthy tissues and organs. The earliest signs of sepsis include fever, chills, reduced body temperature, fast breathing, racing heartbeat, low blood pressure, and mental changes such as confusion.

RELATED: Sepsis symptoms: what are the early signs of sepsis?

Can a tooth abscess appear overnight?

Although the symptoms of a tooth abscess may come on fairly suddenly, the abscess is usually the end result of a series of dental problems. The first and most evident problem is poor dental hygiene or in some cases a broken or cracked tooth. Other dental problems slowly evolve over the months and years like plaque buildup, calculus buildup, tooth decay, swollen gums (gingivitis), cavities, infected teeth (pulpitis), or periodontitis (infection of the inner gums). Most of these problems will have symptoms. Some, like a tooth infection or periodontitis, might have highly noticeable symptoms like severe pain. So, yes, a tooth abscess might be something that appears seemingly out of nowhere one day. However, the whole process takes a long time. At any point in that timeline, intervention helps reverse the process before an abscess forms.

How to tell the difference between a tooth abscess and a gum abscess?

A tooth abscess, or periapical abscess, is caused by a tooth infection spreading out the tooth root to the tissues below. Sometimes an abscess can erupt on the top of an impacted tooth which is alled a pericoronal abscess, this abscess affects the outer soft tissues of the gums called the gingivae. A periodontal abscess develops from a bacterial infection between the tooth and the gums. It affects the inner gum tissues called the periodontium. Both pericoronal and periodontal abscesses are gum abscesses.. At some point before a tooth abscess forms, tooth pain, tenderness, and sensitivity are the dominant symptoms.

What’s next? Additional resources for people with an abscessed tooth

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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