Failure of eruption of a lower third molar with cystic change
27-year-old male
§Chief complaint
Dull ache and swelling behind the last lower right tooth
§Medical & dental history
- 01Healthy
- 0248 never erupted
- 03Two episodes of pericoronitis in the last year
§Clinical examination
- 01Mild buccal expansion distal to 47, mucosa healthy
- 0248 not visible clinically
- 0347 vital, no mobility
- 04Mouth opening 42 mm, no trismus at time of review
§ figuresFigures (3)
Fig. 1dentigerous jaw cyst in the right mandible around and impacted wisdom tooth
“JawCyst (with arrows)” · JawCyst.jpg: Coronation Dental Specialty Group [1] derivative work: Jbarta · CC BY 3.0 · Wikimedia Commons
Fig. 2dentigerous jaw cyst in the right mandible around and impacted wisdom tooth
“JawCyst (with arrows, cropped)” · JawCyst.jpg: Coronation Dental Specialty Group [1] derivative work: Jbarta and M · CC BY 3.0 · Wikimedia Commons
Verified open-access images only, reproduced for education under their stated licences · no AI-generated or illustrative artwork · Dentigerous Cyst figures pending faculty review.
§Differential diagnosis
§Final diagnosis
Dentigerous cyst associated with impacted 48
A well-corticated unilocular pericoronal radiolucency more than 4 mm wide that attaches at the cemento-enamel junction of an unerupted tooth is the defining feature. Only histology excludes a unicystic ameloblastoma presenting identically.
§Investigations
- 01OPG — unilocular corticated pericoronal radiolucency 22 mm around crown of 48
- 02CBCT — roots of 48 in contact with the IAN canal, cortical thinning
- 03Pulp testing of 47 — vital
§Treatment plan
- 01Enucleation of the cyst with removal of 48
- 02Careful nerve-conscious technique given CBCT proximity
- 03Histopathology of the lining
§Surgical procedure
- 01Buccal envelope flap with distal relieving incision
- 02Bone removal, tooth sectioned and delivered, cyst lining enucleated intact
- 03Wound irrigated and closed primarily
§Histopathology report
Cyst wall lined by thin, non-keratinised 2-4 cell layer epithelium without rete ridge formation, mucous cell metaplasia focally, loose fibromyxoid connective tissue wall. Dentigerous cyst; no ameloblastomatous change.
§Follow-up & outcome
- 01Transient lower lip paraesthesia resolving fully by 8 weeks
- 02Radiographic bony fill at 9 months
§Clinical pearls / learning points
- 01Pericoronal space greater than 4-5 mm suggests a cyst rather than a normal follicle.
- 02Coronectomy is an alternative when the IAN is intimately related, but not when cystic change requires full enucleation and histology.
§References
- Neville BW et al. Oral and Maxillofacial Pathology, 5th ed.
§Similar cases
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