A dental abscess is a localised collection of pus caused by a bacterial infection involving the teeth and/or surrounding structures. It usually arises secondary to dental caries, trauma, or a recent dental procedure. Dental abscesses are commonly polymicrobial, involving both aerobic and anaerobic bacteria. While often localised, on occasion, these infections can lead to serious complications such as Ludwig’s angina, retropharyngeal abscess or systemic sepsis.
Pathophysiology
The pathophysiological processes that result in the formation of a dental abscess are as follows:
- Caries formation: Acids produced by bacterial fermentation of dietary carbohydrates erode enamel, introducing bacteria into the pulp and root.
- Infection spread: Local infection advances to the surrounding tissues, forming an abscess or superficial gingivitis. In rare cases, infection spreads to deep facial planes, causing Ludwig’s angina or retropharyngeal abscess.
- Polymicrobial flora: Common pathogens include Streptococcus spp., Staphylococcus aureus, and anaerobes such as Prevotella spp.
Anatomy of the teeth
There are 20 primary teeth (deciduous teeth). These first appear around 6-8 months of age. Secondary teeth (permanent teeth) are usually complete by the age of 18 years. These usually comprise three molars, two premolars, one canine and two incisors in each quadrant of the jaw.
Permanent teeth of the right half of the lower dental arch, seen from above (from Gray’s Anatomy)
Each tooth has three main components:
- The crown
- The neck
- The root
The crown, root, and neck of the tooth (from Gray’s Anatomy)
The root is the fixed part within the alveolus. The neck joins the root and the crown, and the crown projects upwards from the gingiva. Enamel covers the crown, and cementum covers the root.
The pulp cavity lies at the heart of the tooth. The pulp contains nerves, blood vessels, and connective tissue. Infection here causes pain and inflammation, often leading to dental abscesses.
The tooth is secured in the socket by the periodontal ligament, which attaches to the cementum covering the root. This ligament absorbs chewing forces.
The maxillary teeth are supplied by the superior alveolar artery, whilst the mandibular teeth are supplied by the inferior alveolar artery. Both of these are branches of the maxillary artery.
Innervation of the teeth is via the superior and inferior alveolar nerves:
- The superior alveolar nerve supplies sensory innervation to the upper (maxillary) teeth. This is a branch of the maxillary division of the trigeminal nerve.
- The inferior alveolar nerve supplies sensory innervation to the lower (mandibular) teeth. This is a branch of the mandibular division of the trigeminal nerve.
Types of dental abscesses
There are four main types of dental abscess:
- Gingival abscess: This type of abscess only affects the gum tissue, leaving the tooth and periodontal ligament unaffected
- Periapical abscess: This type of abscess originates at the apex of the tooth root. It is the most common type, often resulting from untreated dental caries or trauma.
- Periodontal abscess: This type of abscess occurs in the supporting structures of the tooth (e.g. gums, alveolar bone). It is often associated with periodontal disease or trapped debris.
- Pericoronal abscess: This type of abscess forms around a partially erupted tooth, commonly the lower third molar (wisdom tooth).
Clinical features
Localised symptoms:
- Severe, throbbing pain localised to the affected tooth or surrounding structures.
- Swelling in the gums, jaw, or face.
- Redness and warmth over the affected area
- Tooth sensitivity (pain typically aggravated by biting, chewing, or temperature changes).
- Foul-tasting pus discharge.
Systemic symptoms (severe cases):
- Fever, malaise or rigors.
- Trismus.
- Dysphagia or odynophagia.
- Difficulty breathing (suggestive of airway compromise).
- Definitive signs of airway compromise (stridor, dyspnoea).
Complications
Local spread:
- Osteomyelitis of the jaw.
- Sinusitis.
- Tooth loss.
- Vincent’s angina (trench mouth): Superinfection causing necrotising, ulcerative inflammation of the gingiva and surrounding tissues.
Regional spread:
- Ludwig’s angina: Potentially life-threatening cellulitis of the submandibular, sublingual, and submental spaces of the floor of the mouth. It can progress rapidly, causing airway compromise.
- Retropharyngeal abscess: Infection spreading into the deep neck spaces. Untreated, can result in airway compromise.
- Cavernous sinus thrombosis: Infection spreads via venous drainage from the face into the cavernous sinuses, resulting in thrombosis. Can cause long-term damage to neurological structures and is associated with a high mortality (~30-35%).
Systemic spread:
- Sepsis.
- Abscess formation in distant organs.
Assessment in the Emergency Department
History:
- Duration and onset of pain.
- Any preceding dental issues (e.g. caries, trauma, recent dental work).
- Difficulty eating, swallowing, or breathing.
- Fever or systemic symptoms.
Examination:
- Inspect the oral cavity for swelling, erythema, pus, or tooth decay.
- Palpate the jaw and gums for tenderness or fluctuance.
- Assess for trismus or signs of airway compromise.
- Examine for regional lymphadenopathy or facial swelling.
Investigations
Useful investigations include:
- Blood tests (if systemic involvement is suspected): FBC, CRP, blood cultures.
- X-ray (orthopantomogram): Identifies underlying dental pathology (dental caries, bone loss or abscess).
- CT scan: Useful in severe cases or when there is suspected deep tissue spread (e.g. Ludwig’s angina, retropharyngeal abscess).
Management
Pain management:
- First-line analgesia is usually with NSAIDs (e.g. ibuprofen), which has both anti-inflammatory and analgesic effects and is often preferred for dental pain.
- Paracetamol can also be used, either alone (in patients unable to tolerate NSAIDs) or in combination with NSAIDs for additional pain relief.
- Opioids should be reserved for severe pain as adjunctive therapy when NSAIDs and paracetamol are insufficient.
Antibiotics:
- Antibiotics are not routinely indicated for dental abscessesand should not be prescribed indiscriminately.
- Indications for antibiotics include systemic symptoms (fever, rigors), spreading infection or if the patient is at high risk of complications (e.g. immunocompromise).
- First-line antibiotics: Amoxicillin 500 mg TDS for 5 days or metronidazole 00 mg TDS for 5 days (for anaerobic coverage or penicillin allergy).
- Second-line antibiotics: Add metronidazole to amoxicillin after 48 hours if there is no improvement. Use co-amoxiclav (625 mg TDS) if there is a severe or refractory infection.
- Clarithromycin can be used for penicillin-allergic patients.
Localised treatment:
- Incision and drainage (I&D): Can be performed on accessible fluctuant abscesses. This should generally be undertaken by a dentist. Deeper abscesses require referral to maxillofacial surgery.
- Chlorhexidine mouthwash: Reduces bacterial load and promotes oral hygiene.
Severe or complicated cases:
- Severe or spreading infections, such as Ludwig’s Angina or retropharyngeal abscess, should be referred urgently to oral or maxillofacial surgery.
- The immediate priority should be airway management (consider intubation or surgical airway if compromised).
- Intravenous antibiotics: Co-amoxiclav 1.2 g IV or ceftriaxone 2 g plus metronidazole 500 mg IV
- Support care: Analgesia and IV fluids
- May need admission for surgical drainage of abscess under specialist care.
Referral and follow-up:
- Patients with minor abscesses can generally be discharged with analgesia and antibiotics (if indicated)
- Dental follow-up should be encouraged for definitive treatment of the underlying source.
- Severe or complicated cases should be referred to maxillofacial specialists.
- Patients with systemic symptoms, signs of deep tissue spread, or airway compromise will need hospital admission.
Thank you to the joint editorial team of www.mrcemexamprep.net for this article.
