Mandibular Occlusal Use — MFDS Part 1 MCQ
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Correct answer: A — Demonstrating a radiopaque calculus in the submandibular duct
Explanation lettering: D = shown as B · B = shown as D
A is correct. A mandibular occlusal projection provides a broad view of the floor of the mouth and can demonstrate a radiopaque calculus within the submandibular duct; cross-sectional projections may also help determine its buccolingual position. Bitewing radiographs are preferred for detecting proximal caries. Craniofacial skeletal relationships are assessed using cephalometric radiography. Internal TMJ derangement is a soft-tissue disorder principally assessed with MRI, while osseous disease may require panoramic imaging or CT/CBCT. A mandibular occlusal radiograph does not adequately demonstrate the maxillary sinuses. Not all salivary calculi are radiopaque, so a negative occlusal radiograph does not exclude sialolithiasis and further imaging may be required when clinical suspicion persists.
Reference: Kim JH et al. Comparison of the diagnostic performance of panoramic and occlusal radiographs in detecting submandibular sialoliths. Imaging Science in Dentistry. 2016;46(2):87–92. https://pubmed.ncbi.nlm.nih.gov/27358815/