Intraoral and Extraoral Radiography Techniques

Intraoral Radiographic Techniques

• Types of Intraoral Radiographs
  • Bitewings: Useful for seeing inside the mouth.
  • Paralleling: Technique to minimize distortion.
  • Bisecting: Another common intraoral technique.
  • Occlusal Radiographs: Views the occlusal aspect of the dental arch.
    • Usage:
      • Detecting salivary stones.
      • Identifying supernumerary teeth.
      • Assessing bone injuries.
      • Investigating unexplained swelling or growth.

Reasons for Occlusal Radiographs

• Detects hard structures like salivary stones.
• Mucoceles and soft tissue lesions are not visible.
• Advanced bone loss best viewed with vertical bitewings or periapical imaging.
• TMJ disorders not visible in occlusal radiographs.

Extraoral Radiographic Techniques

• Panoramic Radiographs:
  • Ideal for viewing eruption patterns in mixed dentition.
  • Shows an overall picture of maxilla and mandible.
  • Useful for detecting impacted teeth, trauma, or large lesions.
  • Not standalone; must be supplemented by intraoral images.
  • Correct positioning involves the Frankfurt plane being parallel to the floor.

Full Mouth Series (FMS)

• Top left corner of FMS features maxillary right molar (mirror image concept).

Radiograph Errors and Corrections

• Improper Placement: Not capturing the apex of teeth.
• Foreshortening: Correct by decreasing vertical angulation.
• Elongation: Correct by increasing vertical angulation.
• Horizontal Angulation: Improper angulation causes overlap.
• Cone Cut: Misalignment of the PID with the receptor.
• Movement During Exposure: Causes blurriness due to decreased sharpness.

Positioning Errors with Panoramic Radiographs

• Chin Positioning:
  • Chin down: Angles the Frankfurt plane downward.
  • Chin up: Angles the Frankfurt plane upward.
• Focal Trough Errors:
  • Too far back: Causes magnification of images.
  • Too far forward: Causes minification.

Identification of Dental Restorations

• Amalgam appears more radiopaque compared to composite.
• Gold borders are well-defined compared to amalgam.
  • Example: Second molar (FDi: 3.7) restored with amalgam.

Anatomy Visibility on Radiographs

• Radiopaque: Enamel, dentin, cementum.
• Radiolucent: Pulp, periodontal ligament space.
• Structures like fossae, sinuses, and canals are radiolucent.
• Landmarks like processes (e.g., coronoid process) are radiopaque.

Guidelines for Radiograph Prescription

• Children: Radiographs if proximal surfaces are not visible.
• Teenagers: Typically require bitewings and possibly a pan.
• Adults: Based on clinical signs; no routine frequency.

Summary of Key Radiographic Anatomy

• Radiolucent: Sinuses, fossa, orbits, and canals.
• Radiopaque: Processes, condyles, and tuberosities.