What Is a Tooth Infection?
A tooth infection occurs when bacteria invade the inner tissue of a tooth or the surrounding gum and bone, causing pain, swelling, and sometimes fever.
The most common type is a periapical abscess. This happens when bacteria reach the pulp, the soft tissue inside your tooth that contains nerves and blood vessels. Once bacteria enter the pulp through a deep cavity, crack, or chip, they multiply and create a pocket of pus at the root tip. This pocket is called an abscess. [1]
A second type is a periodontal abscess, which forms in the gum tissue beside the tooth root. Periodontal abscesses are typically linked to gum disease rather than decay. [9] Both types produce overlapping symptoms, but they require different treatment approaches.
Tooth infections are considered dental emergencies because they do not resolve without professional treatment. [1] The infection can remain contained for weeks, giving a false sense that it is improving. However, without removing the source of bacteria, the infection will return or spread.
What Causes a Tooth Infection?
Tooth infections start when bacteria gain access to the inner tooth or surrounding tissues through decay, cracks, or gum disease.
Tooth Decay, Cracks, and Trauma
Deep cavities are the most frequent entry point for bacteria. As decay progresses through the outer enamel and the softer dentin layer beneath it, bacteria eventually reach the pulp chamber. A study correlating clinical and histologic pulp diagnoses found that teeth with deep caries often showed irreversible pulpitis (severe, permanent inflammation of the pulp) or outright pulp necrosis (death of the pulp tissue). [8]
Cracks and fractures in teeth also allow bacteria in. A cracked tooth may not look obviously damaged, but even a hairline fracture can act as a highway for bacteria. Trauma from sports injuries, falls, or biting on hard objects can fracture a tooth or damage the pulp directly, leading to infection weeks or even months later.
Previous dental work can be another factor. Large fillings or crowns sometimes develop micro-gaps at their edges over time. Bacteria seep through these gaps and reach the pulp without any visible cavity on the surface.
Gum Disease and Periodontal Abscesses
Periodontal disease, a chronic infection of the gum and bone around teeth, can produce acute abscesses. When deep pockets form between the gum and tooth root, bacteria become trapped. The pocket can seal over, and the trapped bacteria form an abscess. [9]
Periodontal abscesses tend to cause localized, rapid-onset swelling and pain in the gum. They are more common in patients with existing periodontitis (advanced gum disease) but can also occur around otherwise healthy teeth if food debris or a foreign object becomes lodged beneath the gumline. [2]
Risk Factors That Increase Your Chances
Certain conditions raise the risk of developing a tooth infection. Poor oral hygiene is the most direct factor. Systemic diseases, including uncontrolled diabetes, can impair your immune response and increase susceptibility to infections in the mouth. [6] Conditions that cause dry mouth reduce saliva's natural protective effect against bacteria. [3]
Pregnancy also changes oral health risk. Hormonal shifts can increase gum inflammation and make existing dental problems worse. [10] If you are pregnant and notice any signs of a tooth infection, tell both your dentist and your obstetrician.
When to See a Dentist or Go to the Emergency Room
Any toothache that lasts more than one to two days or comes with swelling warrants a dental visit. Certain symptoms signal a true emergency that requires immediate care.
Red Flag Symptoms
A tooth infection becomes a medical emergency when it begins to spread beyond the tooth and local gum tissue. [1] Go to an emergency room if you experience any of the following:
- Swelling that extends to the eye area, floor of the mouth, throat, or neck
- Difficulty breathing or swallowing
- Fever above 101°F (38.3°C) with facial swelling
- Rapid heartbeat or feeling generally unwell with chills
- Inability to fully open your mouth (trismus)
Symptoms That Need a Prompt Dental Appointment
Not every tooth infection is an emergency room situation, but all of them need professional evaluation. Schedule a dental appointment within a day or two if you notice:
Throbbing or constant toothache that keeps you awake at night. Sensitivity to hot drinks or food that lingers for more than a few seconds after the stimulus is removed. A pimple-like bump on the gum near the sore tooth. A foul taste or intermittent drainage of salty fluid in your mouth. These are signs that infection is present and needs to be addressed before it worsens. [1]
How a Tooth Infection Is Diagnosed
Your dentist or endodontist will use a combination of symptom history, clinical tests, and imaging to find the source and extent of the infection.
Clinical Examination and Tests
The appointment typically starts with questions about your pain: when it started, what makes it better or worse, and whether it wakes you at night. Your dentist will then examine the area visually and press on the teeth and surrounding gum to locate the tender spot.
Pulp vitality testing helps determine whether the nerve inside the tooth is alive, inflamed, or dead. Cold testing involves placing a cold stimulus on the tooth and measuring your response. A tooth with irreversible pulpitis typically produces intense, lingering pain. A tooth with a dead (necrotic) pulp may not respond at all. [8] Your dentist may also tap gently on the tooth. Sharp pain on tapping, called percussion sensitivity, suggests inflammation at the root tip.
Periodontal probing measures the depth of the pocket between the gum and the tooth. Deep pockets can indicate a periodontal abscess or a crack that extends below the gumline. [2]
X-Rays and Advanced Imaging
A periapical X-ray shows the entire tooth from crown to root tip, including the bone around it. An abscess often appears as a dark area at the root tip, indicating bone loss caused by the infection. In some cases, a cone beam CT (CBCT) scan provides a three-dimensional view. CBCT scans help identify fractures, extra root canals, and the precise spread of infection. [11]
These diagnostic steps help your dentist distinguish between a periapical abscess from the tooth pulp, a periodontal abscess from gum disease, or a cracked tooth. The diagnosis determines which treatment path is right for your situation.
Treatment Options for an Infected Tooth
Treatment focuses on removing the source of bacteria. The right option depends on the type of infection, the tooth's condition, and how far the infection has spread.
Immediate Pain and Infection Management
If you see a dentist while the infection is actively flared, the first step is often drainage. The dentist may open the tooth or make a small incision in the gum to let the pus escape. This typically brings rapid relief from pressure and pain.
Antibiotics are prescribed when the infection has spread beyond the tooth into surrounding tissues, or when the patient has fever and facial swelling. However, antibiotics alone do not cure a tooth infection. They reduce the bacterial load temporarily so that definitive treatment can be performed safely. [5] Over-the-counter pain relievers such as ibuprofen and acetaminophen are commonly recommended for managing acute endodontic pain. A 2021 review in Drugs found that combining ibuprofen with acetaminophen provided effective pain relief for most patients with acute endodontic pain. [5]
Root Canal Treatment
Root canal therapy is the primary treatment for saving an infected tooth. During the procedure, the endodontist removes the infected or dead pulp tissue, cleans and shapes the root canals (the hollow channels inside the roots), disinfects them, and fills them with a biocompatible material. A crown is usually placed over the tooth afterward to restore its strength. [11]
An endodontist is a dentist who has completed an additional two to three years of specialized training in diagnosing and treating problems inside the tooth. You can learn more about this specialty on the endodontics page. In some cases, a previously root-canal-treated tooth becomes reinfected. Retreatment, where the old filling material is removed and the canals are re-cleaned, may be needed.
For immature teeth in children or adolescents, regenerative endodontic treatment is sometimes an option. This approach encourages the continued development of the root after infection. A case report documented successful management of an infected immature tooth using regenerative techniques. [4]
Apicoectomy (Root-End Surgery)
When a standard root canal does not fully resolve the infection, an apicoectomy may be recommended. In this minor surgical procedure, the endodontist makes a small opening in the gum, removes the infected root tip and a small amount of surrounding bone, places a tiny filling to seal the root end, and then closes the gum with stitches. [11]
Apicoectomy is typically considered when retreatment through the crown is not practical, such as when a post or a well-fitting crown is present.
Tooth Extraction
Extraction is the last resort when a tooth cannot be saved. Reasons include extensive decay that leaves too little tooth structure, a vertical root fracture, or severe bone loss from advanced periodontal disease. After extraction, replacing the missing tooth with a dental implant, bridge, or removable partial denture helps maintain chewing function and prevents neighboring teeth from shifting.
Both root canal treatment and extraction are effective at eliminating infection. Your dentist or endodontist will discuss which option makes the most sense for your specific tooth, factoring in the tooth's structural condition and your overall oral health.
Periodontal Abscess Treatment
If the infection originates from gum disease rather than from inside the tooth, treatment focuses on cleaning out the periodontal pocket. This may involve scaling and root planing (deep cleaning below the gumline), draining the abscess, and in some cases periodontal surgery to reduce pocket depth. [9] Antibiotics may be used as an adjunct when the infection is severe. [7]
Cost Factors for Diagnosing and Treating a Tooth Infection
The cost of treating an infected tooth depends on the type and extent of the infection, the tooth involved, and the treatment needed.
An emergency dental visit, including X-rays and initial evaluation, typically ranges from $100 to $350. Root canal treatment costs vary significantly by tooth. A front tooth root canal may range from $700 to $1,200, while a molar root canal typically costs $1,000 to $1,800 or more because molars have multiple canals. A crown to restore the tooth afterward generally adds $800 to $1,500. [12]
An apicoectomy typically costs $900 to $1,500 per root. Extraction costs range from $150 to $400 for a simple extraction and $200 to $700 or more for a surgical extraction. Costs vary by location, provider, and case complexity. Dental insurance often covers a portion of these procedures, so checking your benefits before treatment is helpful.
Delaying treatment usually increases the total cost. An infection caught early may need only a root canal. An infection that spreads may require emergency drainage, antibiotics, hospitalization in severe cases, and eventually the same root canal or extraction that was originally needed.
Find an Endodontist Near You
If you have symptoms of a tooth infection, an endodontist can diagnose the problem and provide treatment to save your tooth when possible. Endodontists perform root canal procedures routinely and use advanced imaging and techniques to locate and treat infections that may be difficult to detect. Visit the endodontics page to find a qualified endodontist in your area and learn more about what to expect during treatment.
Search Endodontists in Your Area