Radiology · patient case with 1 question
A line on a lower periapical film
Patient: Male, 58 years old
Chief Complaint: Presents for a routine examination and radiographs.
Background: Hypertension controlled on lisinopril. Generalised moderate chronic periodontitis with horizontal bone loss. Smoker.
Findings: On the periapical of the lower left premolars, a thin, sharply defined RADIOLUCENT LINE runs vertically through the bone between the apices of the two premolars. It is of uniform width along its whole course and faintly corticated. Both premolars respond normally to cold, have no restorations, and are not tender to percussion or mobile.
Question 1
What does this vertical radiolucent line most likely represent?
Show answer and explanation
Correct answer: C. A nutrient canal
- A. A vertical root fracture lies WITHIN the root, not in the interdental bone, and it announces itself with an isolated deep narrow pocket, a halo or J-shaped periradicular lucency and usually a restored or endodontically treated tooth. These premolars are unrestored, vital and symptom-free.
- B. The mental foramen is a ROUND or oval lucency, usually projected at or near the apex of the second premolar. Its shape is entirely different from a long uniform line, though a superimposed foramen is a classic mimic of periapical pathology on this same film.
- C. CORRECT. NUTRIENT CANALS carry a neurovascular bundle through cancellous bone and appear as narrow, uniform, well-defined radiolucent lines running vertically or obliquely. They are seen most often in the ANTERIOR MANDIBLE and BETWEEN THE MANDIBULAR PREMOLARS — exactly this location — and they become conspicuous when the bone is thin, which is why they are more visible in older patients, in hypertensives and in those with periodontal bone loss. This is normal anatomy and requires no action.
- D. The periodontal ligament space follows the OUTLINE of a root as a thin lucency between root and lamina dura. It does not run as a free-standing line through interdental bone, and widening from occlusal trauma is accompanied by mobility — absent here.
Note: Worth grouping with the other normal radiolucencies that get mistaken for disease on mandibular films: the mental foramen, the mandibular canal, the submandibular (lingual) salivary gland depression below the molars, the lingual foramen in the midline, and the marrow spaces between coarse trabeculae.