Cellulitis and Abscess of the Mouth

How mouth infections form and spread

Infections of the mouth are called odontogenic infections when they come from the teeth, which is the case for most of them. Bacteria that normally live in the mouth (streptococci and anaerobes) get into tissue that should be sterile:

1. Decay or a crack lets bacteria reach the tooth's pulp (nerve). The pulp dies.
2. Infection spreads out through the root tip into the jawbone, forming a periapical abscess.
3. Pus pushes through the thinnest bone and collects under the gum. This is the familiar gum boil.
4. If the body cannot wall the infection off, it spreads along tissue planes into the cheek, under the jaw, or into the neck. This diffuse stage is cellulitis.

Abscess and cellulitis are two stages of the same process. Cellulitis comes first or alongside: tissue that is hot, red, firm and diffusely swollen, often within the first 2 to 5 days. An abscess forms when the body walls off the infection into a soft, fluctuant collection of pus.

Symptoms

Symptoms depend on where the infection sits.

Localized abscess

• Severe, throbbing pain in a tooth that may spread to the ear, jaw or neck
• Pain when biting or tapping on the tooth
• A swollen, red bump on the gum next to the tooth
• A foul or salty taste and bad breath if it drains
• Sudden relief of pain if the abscess bursts

Spreading cellulitis

• Swelling of the cheek, under the eye, or along or below the jaw
• Warm, red, tight skin over the swelling
• Fever, chills and feeling unwell (malaise)
• Swollen, tender lymph nodes under the jaw
• Trismus, meaning difficulty opening the mouth, when the chewing muscles are involved

Dangerous deep-space infections

Ludwig's angina is a rapidly spreading cellulitis of the floor of the mouth on both sides, usually from a lower molar. The tongue is pushed up and back, which can block the airway. Other deep infections spread into the throat (parapharyngeal or retropharyngeal space), down to the chest (mediastinitis), or up through veins to the brain (cavernous sinus thrombosis). These are rare but life-threatening and need hospital care.

Causes and risk factors

Common sources

• Tooth decay: untreated dental caries is the leading cause.
• Gum disease: a periodontal abscess forms in a deep gum pocket in people with periodontitis. The tooth is usually alive but loose.
• Wisdom teeth: pericoronitis is infection of the gum flap over a partly erupted lower wisdom tooth. It can spread into the throat and jaw muscles.
• Cracked or broken teeth, and old fillings or crowns that leak.
• Recent dental work, especially extraction.
• Injury to the mouth, piercings, or a foreign body such as a fish bone.

Things that raise the risk of spread

• Diabetes, especially when poorly controlled
• A weakened immune system: chemotherapy, HIV, long-term steroids, organ transplant
• Alcohol or drug use, and delayed dental care
• Previous radiation to the jaw

Diagnosis

A dentist or doctor will:

• ask when the pain started, whether swelling is spreading, and about fever, swallowing and breathing
• examine the mouth, tap and test the teeth, look at the gums, and check how wide you can open
• feel the neck and under the jaw for swelling and lymph nodes

Tests include:

• Dental X-rays to find the source tooth and any bone loss at the root tip.
• Blood tests such as a white cell count and CRP if you are unwell, and blood sugar.
• CT scan with contrast of the face and neck if a deep-space infection is suspected, to show how far it has spread and whether there is pus to drain.
• Pus culture in severe or recurrent cases to guide antibiotic choice.

Treatment

The rule for any mouth abscess is: drain the pus and remove the source. Antibiotics alone rarely cure a dental abscess, because they cannot reach a dead tooth pulp or a pus pocket well.

Dental treatment

• Incision and drainage: a small cut in the gum lets pus escape, giving fast pain relief.
• Root canal treatment: removes the infected pulp so the tooth can be kept.
• Extraction: if the tooth cannot be saved, removing it drains the infection.
• Deep cleaning for a periodontal abscess.

Antibiotics

Antibiotics are used when infection is spreading (cellulitis), when there is fever or swollen glands, or when the immune system is weak. Penicillin-type antibiotics are usual first choices. Others are used for allergy. Finish the course exactly as prescribed.

Hospital treatment

Spreading facial cellulitis, any threat to the airway, or failure to improve within 24 to 48 hours of treatment needs hospital care. This means IV antibiotics, surgical drainage of deep spaces, and sometimes a breathing tube or tracheostomy to protect the airway.

Pain relief at home while you wait

• Ibuprofen or acetaminophen (paracetamol), following the label dose. Ibuprofen is often more effective for dental pain. Avoid NSAIDs if you have kidney problems, stomach ulcers or are told not to take them.
• Warm salt-water rinses help a draining gum boil.
• Do not apply heat to the outside of the face, which can draw infection outward.
• Do not try to pop the abscess yourself.

Complications

• Spread to deep neck spaces, airway blockage and Ludwig's angina
• Osteomyelitis, an infection of the jawbone
• Sepsis, a body-wide reaction to infection
• Spread to the eye socket (orbital cellulitis) or brain veins (cavernous sinus thrombosis)
• Sinus infection from upper back teeth

Outlook and prevention

With prompt drainage and treatment of the tooth, most mouth abscesses settle within a few days and leave no lasting problems. The danger lies in delay. Prevention is mostly about dental health: brush twice daily with fluoride toothpaste, clean between teeth, see a dentist regularly, fix cracked teeth and cavities early, and have troublesome wisdom teeth assessed.

Frequently asked questions

What causes cellulitis in the mouth?

Most oral cellulitis comes from a dental infection: a decayed tooth whose nerve has died, a gum abscess or an infected wisdom tooth. Bacteria spread from the tooth into the soft tissues of the face and jaw. Less often it follows a mouth injury, piercing or dental procedure.

What is the difference between cellulitis and an abscess in the mouth?

Cellulitis is diffuse, firm, spreading infection of the tissue with no pus to drain. An abscess is a contained pocket of pus that feels soft. Cellulitis is treated mainly with antibiotics and removal of the source. An abscess needs drainage.

Can a mouth abscess go away on its own?

No. An abscess may burst and the pain may ease, but the infection stays in the tooth or gum and usually returns or spreads. It needs dental treatment, such as drainage, a root canal or extraction.

How quickly can oral cellulitis become dangerous?

Spreading facial cellulitis can worsen within hours. Swelling under the jaw, trouble swallowing, drooling, a muffled voice or difficulty breathing are emergency signs. Go to an ER or call 911 or your local emergency number.

Will antibiotics alone cure a tooth abscess?

Usually not. Antibiotics can slow spreading infection, but the source, the dead nerve or pus pocket, has to be drained or removed by a dentist. Without that, the infection usually comes back once the antibiotics stop.