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PRC Dentist Licensure study materials
PRC Dentist Licensure study resources

PRC Dentist Licensure: Oral and Maxillofacial Radiology and Diagnostic Imaging

PRC Dentist Licensure · Work through your exam, one topic at a time.

All guide sections

Oral and Maxillofacial Radiology and Diagnostic Imaging

This domain tests image selection, projection geometry, radiation protection and interpretation of the lesions that reappear across oral medicine and surgery questions.

Technique

  • Paralleling technique with a long cone and film holder minimises distortion and is preferred; bisecting-angle is a fallback.
  • Bitewings show interproximal caries and crestal bone; periapicals show the apex; occlusal films show stones and impacted canines; panoramic films survey; CBCT quantifies bone volume, impacted teeth, root fractures and implant sites.
  • Panoramic images magnify by roughly 10–30%, have a focal trough with blurring outside it, and produce ghost images of the opposite side, positioned higher.
  • ALARA: collimation, lead apron with thyroid collar, fastest receptor, and only justified exposures. Pregnancy is not an absolute contraindication to necessary dental imaging.

Interpretation

  • A periapical radiolucency may be granuloma, cyst or abscess - radiography cannot distinguish them; histology is required.
  • Dentigerous cyst: unilocular, attached at the cementoenamel junction of an impacted tooth, enclosing the crown.
  • Odontogenic keratocyst: multilocular, grows along the medullary cavity, high recurrence.
  • Ameloblastoma: soap-bubble appearance with root resorption. Fibrous dysplasia: ground-glass opacity blending into bone; ossifying fibroma: well demarcated.
  • MRONJ: exposed bone with antiresorptive history; radiographic change lags clinical disease.

Worked example

A panoramic radiograph of a 24-year-old shows a well-defined unilocular radiolucency surrounding the crown of an impacted mandibular third molar and attached at its CEJ. Attachment at the CEJ with crown enclosure indicates a dentigerous cyst. A keratocyst attaches further down the root and spreads along the medullary cavity; an ameloblastoma is usually multilocular with root resorption.

Traps

Diagnosing a cyst from a radiograph alone; forgetting ghost images; assuming a radiolucency in a patient on bisphosphonates is periapical pathology; ordering CBCT when a periapical film answers the question.