Periapical Granuloma

Periapical granuloma is a localised mass of chronic granulation tissue at the apex of a non-vital tooth, formed as the host response to canal infection. It is a histological diagnosis, though it is usually inferred from a periapical radiolucency.

Granulomas make up roughly half of periapical lesions removed at surgery, with radicular cysts and scar tissue making up most of the rest, but published proportions vary widely between series.

Pathophysiology. Bacterial products and necrotic pulp tissue drive a chronic inflammatory reaction in the periodontal ligament and bone at the apex. Granulation tissue replaces the bone, and infiltrating lymphocytes, plasma cells, macrophages and fibroblasts wall off the infection.

Epithelial cell rests of Malassez can proliferate within the granuloma and some lesions transform into radicular cysts.

Usually no symptoms. Occasional tenderness to percussion, a discoloured tooth, a past history of toothache that settled, or trauma. Swelling and pain occur only with acute exacerbation. There is no expansion of the cortex in most lesions.

Pulp sensitivity tests are negative, and the tooth may carry a deep restoration or caries.

• Periapical radiograph shows a round or oval radiolucency, typically under 10 mm in diameter, at the apex of a non-vital tooth, with a well defined or poorly defined border. Radiographic features cannot reliably separate granuloma from cyst.
• Cone beam CT for size, buccal or palatal expansion, relation to the sinus or mandibular canal and surgical planning.
• Pulp sensitivity testing to confirm non-vitality.
• Histology of tissue removed at surgery or extraction is the only definitive test: granulation tissue with chronic inflammatory cells, with or without epithelial strands, and no cystic lumen lined by epithelium.
• Send all enucleated tissue for histology, to exclude cyst, keratocyst, tumour and other pathology.

Differential diagnosis.

• Radicular cyst
• Periapical abscess
• Periapical scar tissue after previous treatment
• Periapical cemento osseous dysplasia
• Odontogenic keratocyst
• Central giant cell granuloma
• Metastatic or lymphoproliferative lesion
• Normal anatomy (incisive foramen, mental foramen, maxillary sinus recess)

• Orthograde root canal treatment, or retreatment, with thorough disinfection using sodium hypochlorite 1 to 5.25% irrigation, 17% EDTA, and an intracanal calcium hydroxide dressing for 1 to 4 weeks. Most granulomas heal without surgery as the canal infection is removed.
• Periradicular surgery with curettage of the lesion, root end resection about 3 mm with retrograde filling, when healing fails at 12 months or the canal cannot be retreated. Send the tissue for histology.
• Extraction with curettage when the tooth is unrestorable.
• Antibiotics are not indicated unless there is spreading infection, in which case amoxicillin 500 mg orally three times daily for 5 days (with metronidazole 400 mg three times daily if severe), or clindamycin 300 mg four times daily in penicillin allergy.
• Analgesia: ibuprofen 400 mg every 8 hours with food, with paracetamol 1 g every 6 hours (maximum 4 g daily).

Monitoring. Radiographic review at 6 and 12 months and annually for up to 4 years. A lesion that persists or enlarges after adequate root treatment needs surgery with histology.

Referral and escalation. Refer to an endodontist or oral surgeon for surgery, large lesions over 10 mm, suspected cyst or tumour, or failed treatment. Urgent referral for rapid expansion, numbness, mobile adjacent teeth or a non-healing socket after extraction.