Two normal structures mistaken for pathology

Correct answer: B. The genial tubercles with the lingual foramen

• A. A nutrient canal appears as a narrow linear radiolucency of uniform width running through cancellous bone, not as a dense ring with a central lucency.
• B. CORRECT. The GENIAL TUBERCLES are bony projections on the LINGUAL surface of the mandibular midline giving attachment to the genioglossus and geniohyoid muscles. On a periapical they project as a well-defined RADIOPAQUE RING or doughnut in the midline near the inferior border, with the LINGUAL FORAMEN appearing as the small radiolucency at its centre — the ‘target’ appearance. This is normal anatomy. Its clinical relevance is that the lingual foramen transmits a small artery, which is why HAEMORRHAGE IN THE FLOOR OF THE MOUTH is a recognised and potentially airway-threatening complication of implant placement in the mandibular midline.
• C. A traumatic bone cyst is a considerably larger radiolucency that scallops upward between the roots of vital teeth. It has no dense corticated ring and no central detail.
• D. A periapical granuloma is continuous with the APEX of a NON-VITAL tooth and lacks a dense surrounding ring of bone. These incisors all respond normally to cold, which excludes it.

Note: The mandibular midline on a periapical carries several normal structures that get mistaken for disease: the genial tubercles and lingual foramen, the mental ridge as a pair of radiopaque lines running upward, and the mental fossa as a diffuse radiolucency above it. All are bilateral, symmetrical or midline, and stable across films — which is how they are recognised.

Correct answer: A. The median palatal (intermaxillary) suture — normal anatomy

• A. CORRECT. The MEDIAN PALATAL SUTURE, also called the intermaxillary suture, runs anteroposteriorly in the midline between the two maxillae. On a maxillary occlusal film it appears as a thin radiolucent line beginning between the central incisors and extending posteriorly, often with slightly sclerotic corticated margins. It is normal anatomy at any age. Its clinical relevance is orthodontic: this is the suture opened by RAPID MAXILLARY EXPANSION, and the expansion achievable depends on the patient's age and the degree of sutural interdigitation — which is why skeletal expansion is straightforward in a nine-year-old and requires surgical assistance in an adult.
• B. A palatal fracture line would be irregular and NON-corticated, would follow a history of significant trauma, and would usually be accompanied by displacement, occlusal disruption or mobility of a segment. The stem specifies no trauma and describes sclerotic margins.
• C. A midline alveolar cleft produces a wide, irregular separation with disturbed alveolar contour and abnormal dental anatomy at the cleft margins, not a thin corticated line.
• D. A nasopalatine duct cyst is a ROUND, oval or heart-shaped radiolucency at or just posterior to the incisive foramen — not a thin line running the length of the palate. It is diagnosed when it exceeds roughly 6 mm or produces symptoms or expansion.

Note: The maxillary occlusal film contains a cluster of normal midline structures worth naming confidently: the median palatal suture, the incisive foramen and canal, the nasal septum with the two nasal fossae flanking it, and the anterior nasal spine. Confusing any of them for pathology leads to unnecessary investigation of a healthy child.