Dental Radiology and Diagnostic Imaging
This domain tests image selection, radiation protection and interpretation of dental radiographs and CBCT. The exam rewards the principle that imaging must answer a clinical question and use the lowest reasonable dose.
Image selection
- Bitewings detect proximal caries and crestal bone levels. Periapicals show individual roots, periapical tissues and endodontic anatomy. Panoramic images survey the jaws, third molars and trauma but have lower resolution.
- CBCT provides three-dimensional information for impacted teeth, complex anatomy, fractures and implant planning, but dose is higher than plain films.
- Apply ALARA and justify every exposure. Use lead aprons and collimation; avoid repeat exposures.
Interpretation
- Describe radiolucency or radiopacity, location, size, margins, effect on adjacent structures and cortical involvement.
- Common findings include periapical radiolucency, widened periodontal ligament, caries, cysts, odontogenic tumours, fractures and retained roots.
Worked example
A patient has suspected proximal caries between lower molars. Reasoning: bitewing radiographs are the correct first choice because they show interproximal surfaces and bone levels at low dose. A panoramic radiograph is not appropriate for caries detection.
Traps that cost marks
A radiolucency is not a diagnosis. Panoramic images are not for caries. Ghost images and superimposition can mimic disease. CBCT is not a routine substitute for plain films. Do not ignore incidental findings, but do not over-treat them.