Radiology · patient case question
The triangular radiopacity superimposed in the corner of the maxillary periapical is which normal structure?
Patient case: Eight-year-old with an unerupted central incisor
Patient: Male, 8 years old, accompanied by his mother
Chief complaint: Mother: “His front tooth still hasn't come in and the other one came in a year ago.”
History: Healthy. No trauma history. No medications.
Findings: Mixed dentition. Tooth #9 is erupted; #8 is unerupted with adequate space. A periapical of the anterior maxilla is of poor quality, but an inverted conical tooth is visible in the midline above the incisor roots. A triangular radiopacity appears in the corner of the film.
Show answer and explanation
Correct answer: B. Coronoid process of the mandible
- A. The anterior nasal spine is a V-shaped midline radiopacity above the central incisors — a midline structure, not a corner one.
- B. CORRECT. The coronoid process appears as a triangular radiopacity in the inferior-posterior corner of maxillary molar and, with certain projections, maxillary periapical films. It is projected into the field when the patient opens wide, because opening carries the coronoid forward and upward beneath the zygomatic arch. Recognising it prevents it being read as a tuberosity lesion or retained root.
- C. The hamulus is a small hook-like projection posterior to the maxillary tuberosity, visible as a slender finger of bone rather than a broad triangle.
- D. The zygomatic process of the maxilla appears as a U- or J-shaped radiopacity superimposed over the maxillary first molar apices, not as an isolated triangle in the corner.
Note: Ask the patient to close slightly and retake if the coronoid obscures the region of interest.