Radioanalysis of impacted teeth

Canine localization

  • Parallax in horizontal plane: Two IOPA or USO + IOPA
  • Parallax in vertical plane: OPG (↑8°) + USO (↓65-70°) to horizontal plane
  • SLOB: Same Lingual Opposite Buccal
  • If in line with arch, will not move
  • Can do CBCT

Third molars

X-rays used:

  • IOPA – difficult due to gagging
  • OPG
  • Oblique lateral view
  • Lower/upper oblique occlusal view – buccolingual position
  • CBCT

1. Angulation

Angulation of impacted molar

2. Crown

  • Size
  • Shape
  • Dental caries
  • Resorption

3. Roots

  • Number of roots
  • Shape
  • Stage of development
  • Curvature – favorable/unfavorable
Impacted tooth root curvature - favorable/unfavorable

4. Relation to ID canal

5. Depth of tooth in alveolar bone

a. CBCT measurement tools

b. Winter’s lines method

  • 1st line (white): Occlusal surface of 1st and 2nd molar
  • 2nd line (amber):
    • Crest of interdental bone between 1st and 2nd molar
    • Extending distally along internal oblique ridge
    • Indicates amount of investing bone surrounding the tooth
  • 3rd line (red):
    • Perpendicular line dropped from white line to point of application
    • Measured from amber line to point of application
    • If red line > 5mm – difficult extraction
Winter's lines third molar impacted

c. Using roots of 2nd molar

Impacted third molar, use second molar relation

6. Buccal or lingual obliquity

  • Determine line of tooth in horizontal plane
  • Buccal obliquity – Crown inclined towards cheek
  • Lingual obliquity – Crown inclined towards tongue
  • Use:
    • Lower oblique occlusal
    • Lower 90° occlusal view

7. Others

a. Surrounding bone

  • Position of ascending ramus to determine access of tooth and the overlying bone
  • Density of bone
  • Evidence of pericoronal infection

b. Lower 2nd molar

  • Crown – Condition of restoration, caries, resorption
  • Root – Number, shape, periodontal status, condition of apices