Dental Radiology Notes

Basic Definitions

  • Radiography: Techniques for producing radiographs.
  • Radiology: Interpretation of radiographs and other diagnostic images.
  • Radiograph: Image produced on a sensitive plate or film by x-rays.
  • X-ray: Type of ionizing radiation.

Necessity of Radiographs

  • Justify all radiographs (reason and information to be gained).
  • No screening radiographs in dentistry.
  • Radiographs should not replace clinical examination and history.
  • Weigh benefits against risks.
  • May indicate need for further investigation.

Indications for Radiographs

  • Diagnosis (adjunct to clinical exam):
    • Caries (primary, secondary, proximal, occlusal, buccal/palatal/lingual).
    • Pulpal and periodontal disease.
    • Unerupted, impacted, missing & supernumerary teeth.
    • Trauma (root & alveolar fractures, foreign bodies).
    • Extractions & replacing teeth.
    • Bone & soft tissue pathology.
  • Treatment planning.
  • Treatment (e.g., endo).
  • Monitoring (disease progression, treatment effectiveness).

Radiography Types:

  • Intra-oral: radiographic detector inside the mouth
    • Bitewing: crowns, cervical portion of roots, surrounding periodontal ligament and alveolar bone
      • detection of dental caries (proximal/occlusal).
      • non-carious tooth loss.
      • monitoring the progress of any loss of tooth structure.
      • assessment of existing restorations and periodontal status.
    • Periapical: 1-3 complete teeth and surrounding periodontal ligament and alveolar bone.
      • detection of apical infection/inflammation.
      • trauma to teeth & supporting bone.
      • assessment of root morphology before extractions.
      • endodontic diagnosis, planning, treatment & monitoring.
      • periodontal assessment.
    • Occlusal: maxilla or mandibular arch including teeth, periodontal ligaments, alveolar bone and some basal bone
      • presence / absence of developing teeth.
      • supernumerary teeth, impacted teeth.
      • pathology not fully demonstrated in a bitewing or periapical.
      • contour of buccal and lingual cortical plate (usually mandible).
      • when unable to take intra-oral radiographs.
  • Extra-oral: radiographic detector outside the mouth
    • Plain skull radiographs
      • lateral cephalometric.
      • antero-posterior view.
      • postero-anterior views (less radiation to eyes and magnification of facial bones than AP).
      • lateral oblique jaw.
      • temporomandibular joint.
    • Pantomography: Dental panoramic radiograph (DPR)
    • Hand-wrist radiograph: skeletal maturity
  • Images using contrast compounds
    • Arthrogram temporomandibular joint
    • Sialogram salivary glands
  • Magnetic resonance imaging (MRI)
    • gives better soft tissue images than CT scans
    • no radiation - uses magnetic field and sound waves
    • very good diagnostic information
    • used in oral maxillofacial surgery (esp soft tissue pathology)
  • Multidetector/multislice Computed Tomography (MDCT/MSCT)
    • late 1990s.
    • Image captured by multiple detectors.
    • multiplanar reformation → reconstructed data can be viewed in any plane as desired.
  • Cone beam computerised tomography (CBCT)
    • provides 3D rendering of structures
    • dental and head & neck applications – bone – dental hard tissues – airways
    • soft tissues not imaged well – becoming widespread – lower dose than MDCT

Usage in Australia (ARPANSA 2005)

  • 10,000,000 intra-oral exposures per year (*42)
  • 500,000 panoramics per year (*99)
  • Total revenue = $$*$469,500,000
  • * based on ADA survey 2012

Detectors

  • Rigid CCD Digital Sensor
  • F-Speed Dental Film
  • Digital Phosphor Plate