What is an alveolar (radicular/periapical) cyst, how does it present, and what is the recommended treatment?

Alveolar (Radicular/Periapical) Cyst

Definition and Pathophysiology

A radicular cyst is an inflammatory odontogenic cyst that develops from epithelial cell rests of Malassez in the periodontal ligament following dental pulp necrosis and chronic periapical inflammation. 1, 2

• The cyst originates from bacterial infection causing pulpal necrosis, which triggers inflammatory stimulation of dormant epithelial remnants in the periodontal ligament area 2
• It is the most common odontogenic cyst of inflammatory origin, typically associated with permanent teeth 3
• The lesion is considered a "true cyst" because it contains a fluid-filled cavity lined by epithelium 1

Clinical Presentation

Most radicular cysts are asymptomatic and discovered incidentally during routine radiographic examination. 2

Common Features:

• Usually painless unless secondarily infected 3
• Most frequently affects the maxillary anterior region (especially maxillary central incisors), followed by mandibular first molars 1, 2
• Typically manifests in later life due to prolonged etiology 1
• May present as bony hard swelling when large 3
• Associated tooth is non-vital with history of untreated caries or trauma 1

Clinical Examination Findings:

• The affected tooth shows signs of pulpal necrosis (discoloration, non-responsive to vitality testing) 2
• Vestibular fistula may be present near the apex of the involved tooth 4
• Large lesions can cause facial asymmetry or bony expansion 5

Diagnostic Approach

Radiographic Evaluation

Intraoral periapical radiography using a dedicated film holder and beam aiming device is the first-line imaging modality for suspected periapical cysts. 6

• Typically appears as a well-defined, unilocular radiolucency encompassing the tooth apex 1, 5
• Multilocular presentations are extremely rare but have been reported 3
• CBCT is explicitly NOT indicated in the initial diagnostic phase, despite superior accuracy 6
• If a fistula is present, obtain the radiograph with a gutta-percha cone inserted into the fistula tract to trace its origin 4, 6

Differential Diagnosis Considerations:

The radiographic appearance requires differentiation from 5:

• Dentigerous cyst
• Ameloblastoma
• Odontogenic keratocyst
• Periapical central giant cell granuloma 7
• Pindborg tumor

Critical Diagnostic Pitfall:

Periapical giant cell lesions can mimic radicular cysts radiographically, especially in root-filled teeth. 7 Always submit surgical specimens for histopathological examination to confirm the diagnosis, as misdiagnosis can lead to inappropriate treatment 7.

Treatment Recommendations

Definitive treatment requires surgical intervention combined with management of the causative tooth. 4

Treatment Algorithm:

For Small to Moderate Lesions:

• Extract the offending tooth and perform cystectomy (complete surgical enucleation) 5
• Thoroughly rinse the cystic cavity 4
• Primary closure when possible 5

For Large Lesions (Especially in Esthetic Zones):

A staged approach is recommended to preserve ridge volume for future implant placement. 4

1. Initial Phase:

   • Extract the causative tooth 4
   • Allow 2 months healing if extensive bone involvement 4

2. Surgical Phase (2 months post-extraction):

   • Perform cystectomy with complete removal of cystic lining 4
   • If adjacent teeth are involved, perform simultaneous apicoectomy with retrograde filling 4

3. Ridge Preservation (Same Surgery):

   • Use autogenous bone chips combined with deproteinized bovine bone mineral particles 4
   • Cover with collagen membrane 4
   • Achieve tension-free primary wound closure 4

4. Implant Placement (6 months later):

   • Late implant placement (Type III protocol) into healed ridge 4
   • Additional facial bone augmentation if needed 4

Follow-Up Protocol

Radiographic follow-up is essential to confirm healing and detect recurrence. 4, 8

• Obtain periapical radiographs at 3 months, 6 months, 1 year post-treatment 4, 8
• Continue annual radiographic assessment for 3 years 4, 8
• Monitor for signs of incomplete healing or recurrence 4

Common Pitfalls to Avoid

• Do not assume all periapical radiolucencies are radicular cysts—always obtain histopathological confirmation, as giant cell lesions can appear identical radiographically 7
• Do not order CBCT as initial imaging—this exposes patients to unnecessary radiation when standard periapical radiographs suffice 6
• Do not neglect adjacent teeth—large cysts may affect neighboring tooth vitality, requiring apicoectomy 4
• Do not skip histopathological examination—surgical specimens must be submitted to confirm diagnosis and rule out other pathology 5, 7
• Do not perform immediate implant placement—when large periapical lesions are present, prolonged healing (16+ weeks) is necessary before implant placement to ensure adequate bone regeneration and primary stability 4