Radicular Cyst
The most common odontogenic cyst, arising at the apex of a non-vital tooth
Prevalence: Accounts for approximately 52-68% of all jaw cysts; found at apex of teeth with necrotic pulps in up to 15% of cases on radiographic studies
Overview
A radicular cyst (periapical cyst) is an inflammatory odontogenic cyst that develops at the apex of a tooth with a necrotic or infected pulp.
It originates from epithelial cell rests of Malassez — remnants of the Hertwig's epithelial root sheath that persist in the periodontal ligament — stimulated by chronic periapical inflammation.
Despite being the most common jaw cyst, radicular cysts grow slowly, are often asymptomatic, and are discovered incidentally on routine radiographs. They can eventually cause jaw expansion and tooth displacement if untreated.
Etiology and Risk Factors
The essential prerequisite is pulp necrosis — caused by caries, trauma, restorative procedures, or periodontal disease — allowing bacteria and their toxins to reach and stimulate the periapical tissues.
Chronic periapical inflammation stimulates the resting epithelial cell rests of Malassez (ERM) in the periodontal ligament to proliferate, forming an epithelial lining around the inflammatory focus.
The inflammatory process initiates this sequence: bacterial toxins → periapical granuloma → ERM proliferation → epithelial-lined cyst cavity → cyst expansion.
Residual radicular cyst: when a tooth is extracted without removing the attached cyst, the cyst may persist and continue growing — a residual radicular cyst.
Professional Content
Full clinical detail — pathogenesis, ICD-10 classification, diagnostic criteria, treatment protocols, and interactive quiz — is available with a Professional subscription.
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Pathogenesis
Three theories explain cyst cavity formation: (1) nutritive theory — central epithelial cells undergo necrosis due to inadequate nutrition and form a cavity; (2) abscess theory — a microabscess forms in the granuloma and becomes lined by proliferating epithelium; (3) secretory theory — epithelial lining secretes products that accumulate, forming the cystic cavity.
Classification
Radicular Cyst (Periapical Cyst)
Cyst at the apex of a non-vital tooth, attached to the root.
Residual Cyst
Persists after extraction of the offending tooth.
Clinical Manifestations
Most radicular cysts are asymptomatic and discovered incidentally on routine periapical or panoramic radiographs.
Diagnosis
Radiographic appearance: well-defined, round or ovoid periapical radiolucency with a corticated (white) border — the cortical lining indicates a slow-growing, benign lesion.
Treatment Protocol
Non-Surgical: Root Canal Treatment
For small to medium cysts where the epithelial lining may regress after periapical healing
Prognosis
Excellent prognosis with appropriate treatment. After successful root canal treatment, most lesions resolve within 6-24 months.
Prevention
- Prompt treatment of carious teeth before pulp involvement
- Timely endodontic treatment of non-vital teeth
Interactive Quiz
Test your understanding of Radicular Cyst.
Q1. What cells are responsible for the epithelial lining of a radicular cyst?
3D Pathology Description
Demonstrate a tooth with necrotic pulp at the apex, surrounded by the fibrous cyst wall with stratified squamous epithelial lining, cystic cavity containing serous fluid, cholesterol clefts, and surrounding bone resorption — with a visible white corticated border on the 3D model.