Radiology · patient case question
What does this radiolucency most likely represent?
Patient case: Cervical radiolucency in a young patient with reflux
Patient: Male, 21 years old
Chief Complaint: “No pain — my dentist saw something on the x-ray.”
Background: College student under considerable exam stress. Diagnosed gastro-oesophageal reflux with frequent regurgitation. Reports clenching. No trauma, no orthodontic history, no internal bleaching.
Vital Signs: BP 120/74 mmHg · HR 76 bpm
Findings: Periapical radiograph shows an irregular, moth-eaten RADIOLUCENCY in the CERVICAL third of the root of a posterior tooth, with the outline of the pulp canal still traceable THROUGH the lesion. The tooth is vital on cold testing, non-tender to percussion, with no periapical change. Clinically there is generalized erosion with cupping of the occlusal surfaces.
Show answer and explanation
Correct answer: D. External cervical resorption
- A. Root caries requires an EXPOSED root surface, which means recession. It is a surface lesion in an older or periodontally involved patient, saucer-shaped and soft to probing, not an intraradicular moth-eaten lucency.
- B. INTERNAL resorption arises from the pulp itself, so it produces a SYMMETRICAL, balloon-like expansion in which the original canal outline is LOST because the lesion IS the canal. It also requires an inflamed pulp, whereas this tooth is vital and asymptomatic.
- C. Cervical burnout is a radiographic ARTEFACT — a diffuse radiolucent band between the enamel edge and the alveolar crest caused by differential absorption at the thin cervical constriction. It is bilateral, uniform, follows the tooth outline, and has no irregular margin.
- D. CORRECT. EXTERNAL CERVICAL RESORPTION begins in the periodontal ligament just apical to the epithelial attachment, where a breach in the protective cementum layer lets clastic cells reach dentine. The radiographic signature is the one described: an IRREGULAR, MOTTLED lucency in the cervical third with the CANAL OUTLINE STILL VISIBLE running through it, because the resorptive process surrounds the canal rather than arising from it. The pulp stays VITAL until very late. Recognised triggers include trauma, orthodontics, internal bleaching, periodontal treatment, bruxism and — as here — chronic acid exposure from REFLUX.
Note: The single test that separates the two resorptions on a plain film is the PARALLAX or SLOB shift: an INTERNAL lesion stays centred on the canal when the beam angle changes, because it is the canal; an EXTERNAL lesion MOVES relative to it. CBCT is definitive and is what determines whether the lesion is restorable. Management depends on Heithersay class — restore the defect where accessible, add root canal treatment where the pulp is involved, extract when the lesion is circumferential and subcrestal.