CBCT Indications — MFDS Part 1 MCQ
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Correct answer: D — Assessment of an impacted mandibular third molar when panoramic imaging shows a close relationship with the inferior alveolar canal and three-dimensional findings are expected to alter the surgical plan
Explanation lettering: B = shown as A · C = shown as B · D = shown as C · A = shown as D
A is correct. CBCT is not routine for impacted mandibular third molars merely because the roots appear close to the inferior alveolar canal. It may be justified in a carefully selected case when conventional imaging demonstrates a close relationship and the three-dimensional information is expected to change management, such as the choice between complete removal and coronectomy or the operative approach. Routine caries assessment uses appropriately selected conventional radiographs, usually bitewings, according to individual risk. CBCT is not a routine method for assessing periodontal bone support; periapical radiographs are generally preferred when imaging is indicated. Orthodontic and review radiographs must also be individually justified rather than prescribed for every patient or at fixed annual intervals.
Reference: Faculty of Dental Surgery, Royal College of Surgeons of England. Parameters of care for patients undergoing mandibular third molar surgery, Executive summary and Appendix 5: Radiological considerations. 2020; updated April 2021. https://www.rcseng.ac.uk/-/media/Files/RCS/FDS/Guidelines/3rd-molar-guidelines--April-2021-v4.pdf