Dental abscess
Exam Tips
- In OSCEs, always separate definitive treatment (dental drainage/extraction/root canal) from temporizing treatment (analgesia +/- antibiotics).
- State clearly that antibiotics are not routine for a localized abscess in a well patient; they are adjuncts when there is systemic upset, spread, or high-risk comorbidity.
- Memorize red flags for emergency admission: airway compromise signs, floor-of-mouth swelling, rapidly progressive facial/neck swelling, orbital or neurological signs, and sepsis physiology.
- Differentiate periapical abscess (caries/trauma -> pulp necrosis -> apical infection) from periodontal abscess (infected obstructed periodontal pocket).
- Use safe prescribing language: check allergies, interactions, renal/hepatic risk, pregnancy status, and maximum daily analgesic doses.
Definition
A dental abscess is a localized collection of pus arising from bacterial infection in a tooth, its root apex, or the surrounding periodontal tissues. In clinical practice it is usually categorized as periapical (from an infected/necrotic pulp, often after caries or trauma) or periodontal (from an infected periodontal pocket with impaired drainage), and both can progress to deep neck space infection if not definitively treated.
Pathophysiology
Most dental abscesses are polymicrobial odontogenic infections driven by oral streptococci and anaerobes (commonly Fusobacterium, Prevotella, and Porphyromonas species). In periapical disease, enamel/dentine breach allows bacterial entry into pulp, causing pulpitis, pulpal necrosis, and extension through the apical foramen into periapical bone and soft tissue; in periodontal disease, obstruction of a deep periodontal pocket traps bacteria and pus. Rising tissue pressure causes severe throbbing pain, and infection may track along fascial planes to submandibular/sublingual spaces (including Ludwig’s angina) or, less commonly, cranial structures. For revision, correlate with a standard oral surgery diagram of fascial space spread from mandibular molars.
Risk Factors
- Poor oral hygiene
- Dental caries
- Chronic periodontal disease
- Dental trauma
- Partially erupted or impacted tooth
- Immunocompromise (including extremes of age)
- Diabetes mellitus
- History of head and neck radiotherapy
- Smoking, alcohol or drug misuse
- Malnutrition
- Xerostomia-inducing medicines (for example anticholinergics, antihistamines, antidepressants)
Clinical Features
Symptoms
- Acute-onset severe throbbing toothache worsening over hours to days
- Pain on biting/chewing and thermal sensitivity (hot/cold)
- Unpleasant taste or history of pus discharge
- Fever, malaise, reduced appetite (especially in children)
- Trismus or dysphagia in more severe infection
- Sleep disturbance due to pain
Signs
- Localized gingival or alveolar swelling with tenderness and warmth
- Facial swelling, sometimes with overlying cellulitis
- Tender, mobile, elevated, broken, or carious tooth
- Purulent intraoral or extraoral drainage/sinus tract
- Regional cervical lymphadenopathy
- Red flags: floor-of-mouth swelling, drooling, uvular deviation, periorbital swelling, reduced tongue mobility, stridor, sepsis physiology
Investigations
Management
Lifestyle Modifications
- Urgent same-day dental review for definitive source control; analgesia alone is not curative
- Soft diet, chew on unaffected side, avoid very hot/cold food and drink
- Use a soft toothbrush; avoid flossing the affected tooth while acutely painful
- Maintain hydration and clear safety-net advice (return urgently if swelling spreads, fever rises, swallowing/breathing worsens)
Pharmacological Treatment
Analgesics (first-line while awaiting dental treatment)
- Ibuprofen 400 mg orally three times daily with food (adult)
- Paracetamol 1 g orally four times daily, maximum 4 g/day (adult)
Prefer ibuprofen if suitable; use paracetamol when NSAIDs are contraindicated or not tolerated. NSAID cautions: active peptic ulcer disease, significant renal impairment, NSAID-sensitive asthma, anticoagulant use, heart failure, and third-trimester pregnancy. Warn not to exceed maximum doses or duplicate over-the-counter combination products.
Antibiotics (adjunct only when systemic involvement, spreading infection, or high-risk host)
- Amoxicillin 500 mg orally three times daily for 5 days (may increase to 1 g three times daily in severe infection)
- Phenoxymethylpenicillin 500 mg orally four times daily for 5 days (may increase to 1 g four times daily in severe infection)
- Metronidazole 400 mg orally three times daily for 5 days (alternative if penicillin allergy or adjunct for anaerobic coverage)
- Clarithromycin 500 mg orally twice daily for 5 days (if penicillin allergy)
Antibiotics do not remove the source and should not delay dental drainage/extraction. Check allergy history carefully. Important safety issues: metronidazole interacts with alcohol (avoid during and for 48 hours after), and may potentiate warfarin; macrolides can prolong QT interval and interact with statins/other CYP3A4 substrates.
Surgical / Interventional
- Definitive dental source control: incision and drainage of abscess where appropriate
- Extraction of non-restorable tooth or endodontic treatment (root canal) for salvageable tooth
- Periodontal debridement and drainage for periodontal abscess
- Emergency hospital management for red flags: airway protection, surgical drainage of deep neck spaces, and intravenous antibiotics
Complications
- Tooth loss
- Chronic sinus tract or fistula (intraoral or cutaneous)
- Facial cellulitis or periorbital cellulitis
- Maxillary sinusitis
- Osteomyelitis of jaw
- Retropharyngeal/deep neck space abscess and descending mediastinitis
- Ludwig’s angina with airway compromise
- Cavernous sinus thrombosis, meningitis, encephalitis, or brain abscess
- Sepsis
Prognosis
Prognosis is usually excellent when prompt dental drainage and source control are achieved. Delayed or incomplete treatment increases risk of recurrence, tooth loss, and potentially life-threatening cervicofacial spread, particularly in immunocompromised, very young, or elderly patients.
Sources & References
🏥BMJ Best Practice(7)
✅NICE Guidelines(1)
- Dental abscess[overview]