Periodontal Abscess

A periodontal abscess is a localised collection of pus within the periodontal tissues, usually in a pre-existing periodontal pocket, with destruction of the periodontal ligament and alveolar bone. It is an acute exacerbation of periodontitis and may occur in a patient who did not know they had gum disease.

• Mechanisms: closure of the pocket entrance with pus trapped inside (deep, narrow pockets and furcations), impaction of foreign material (food, floss, dental dam, orthodontic elastics), incomplete removal of calculus during scaling (calculus fragments pushed into the tissue), systemic antibiotics that change the pocket flora without treating the pocket, perforation of the root, and vertical root fracture.
• Risk factors: untreated periodontitis, diabetes mellitus, smoking, immunosuppression, and poor oral hygiene.
• It is one of the commonest dental emergencies and a recognised cause of tooth loss.
• Bacteria are mixed anaerobes (Porphyromonas gingivalis, Fusobacterium, Prevotella, spirochaetes).

• Rapid onset of deep throbbing pain, a swollen, red, smooth and ovoid gingival swelling along the side of a tooth, tenderness on biting, and a sensation that the tooth is elevated and "high".
• Suppuration from the pocket, bleeding, bad breath and taste.
• Tooth mobility and extrusion, percussion tenderness on lateral pressure, deep probing depths (usually over 5 mm), and furcation involvement.
• Pulp remains vital (unlike a periapical abscess), unless an endodontic periodontal lesion is present.
• General: low grade fever, malaise, regional lymphadenopathy; rarely facial cellulitis, trismus, fascial space infection, or bacteraemia.
• Red flags: spreading facial or neck swelling, difficulty swallowing or breathing, floor of mouth swelling, rigors, or ill appearance.

• Clinical: probing for pocket depth with pus, bleeding on probing, mobility and percussion; palpation of the swelling.
• Vitality testing (cold, electric pulp test) to separate from a periapical abscess; periapical radiograph (and bitewings) to show bone loss, vertical defects, radiolucency along the root and calculus; cone beam computed tomography for complex cases.
• Check temperature, pulse, blood pressure, and lymph nodes; in unwell patients FBC, CRP, glucose, urea and creatinine.
• Look for diabetes (HbA1c), HIV, and other risk factors in recurrent abscesses.
• Differentials: gingival abscess, periapical abscess, endodontic periodontal lesion, vertical root fracture, pericoronitis, necrotising periodontal disease, osteomyelitis, and tumour (rare).

Drainage and debridement (first and most important step)

• Anaesthetise (lidocaine 2 percent with adrenaline 1 in 80 000, up to 3.6 mL); drain through the pocket by gentle probing and compression, or incise the fluctuant swelling with a number 15 blade at the most dependent point; irrigate with saline or chlorhexidine 0.2 percent; carry out thorough ultrasonic and hand debridement of the root surface if the patient tolerates it.
• Tooth with hopeless prognosis (severe bone loss, mobility, vertical fracture, furcation lesion): extract, which resolves the abscess.

Antibiotics (adjunct, only when there is systemic involvement or spreading infection, or in immunosuppression)

• Amoxicillin 500 mg orally three times daily for 5 days, with metronidazole 400 mg orally three times daily for 5 days (children: amoxicillin 40 mg/kg/day in three divided doses, metronidazole 7.5 mg/kg three times daily).
• Penicillin allergy: clarithromycin 500 mg orally twice daily for 5 days with metronidazole 400 mg three times daily for 5 days, or doxycycline 100 mg orally daily after a 200 mg loading dose (not in children under 12 years or pregnancy).
• Severe infection or deep space spread: admit for intravenous co-amoxiclav 1.2 g every 8 hours, or benzylpenicillin 1.2 g every 6 hours with metronidazole 500 mg every 8 hours, and surgical drainage.
• Antibiotics alone, without drainage, do not cure the abscess and promote recurrence.

Symptom relief

• Paracetamol 1 g every 6 hours (maximum 4 g daily) with ibuprofen 400 mg every 8 hours with food for 3 to 5 days; avoid ibuprofen in renal impairment, peptic ulcer, and in the last trimester of pregnancy.
• Warm salt water rinses every 2 hours; chlorhexidine 0.2 percent 10 mL twice daily for up to 2 weeks; soft diet.

Definitive periodontal treatment

• After the acute phase (usually 1 to 2 weeks), full periodontal assessment with scaling and root surface debridement, oral hygiene instruction, risk factor control (stop smoking, glycaemic control), re-evaluation at 6 to 8 weeks, and periodontal surgery or regeneration if pockets persist.
• Review at 24 to 48 hours; urgent referral for spreading infection.

Diabetes

• Check glucose; optimise control (HbA1c of 53 mmol/mol, 7 percent, or lower is a usual target); monitor closely during infection.