Ectopic Canine — ORE Part 1 MCQ
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Correct answer: C — Two periapical radiographs using horizontal parallax
The correct answer is C. In a 10-year-old with a non-palpable upper canine, the position must be localised radiographically. UK guidance recommends two radiographs taken with a change in tube-head position, applying horizontal or vertical parallax. Two periapicals are an accepted horizontal-parallax pair and permit labio-palatal localisation. A panoramic radiograph or anterior occlusal radiograph alone gives only one projection and cannot reliably establish the bucco-palatal position. A lateral cephalogram is principally for skeletal and orthodontic assessment, not localisation of an ectopic canine. Small-field CBCT can provide detailed three-dimensional information, including assessment of possible incisor root resorption, but is reserved for selected cases in which conventional imaging is insufficient for treatment planning because it usually entails a higher radiation dose.
Reference: Royal College of Surgeons of England, Faculty of Dental Surgery. Management of the Palatally Ectopic Maxillary Canine, Radiographic examination, 2023. https://www.rcseng.ac.uk/-/media/Files/RCS/FDS/Guidelines/Management-of-the-Palatally-Ectopic-Maxillary-Canine--revised-with-edits-25-Jan-2023.pdf