How can external resorption be distinguished from internal resorption radiographically?

How can external resorption be distinguished from internal resorption radiographically?

• A. External resorption shows loss of root structure from the external surface with intact canal space; internal resorption centers within canal lumen and expands outward
• B. Internal resorption shows loss of root structure from the external surface
• C. They look identical on radiographs
• D. Distinction cannot be made radiographically

Answer: (A)

Focusing on where the resorption originates relative to the pulp space lets you tell external from internal on radiographs. External resorption begins at the outer surface of the root and progresses inward, so you see loss of root structure from the external surface while the canal space remains normal and intact. Internal resorption starts inside the pulp space and expands outward, so the canal lumen itself enlarges or “balloons” on the radiograph while the external root outline stays comparatively intact. Because of this, an external lesion shows a radiolucency at the root surface with an unchanged canal, whereas an internal lesion shows widening of the canal space. In practice, changing the radiographic angle can help confirm: internal resorption stays centered in the canal, external resorption shifts with the tooth and lies external to the canal.

Focusing on where the resorption originates relative to the pulp space lets you tell external from internal on radiographs. External resorption begins at the outer surface of the root and progresses inward, so you see loss of root structure from the external surface while the canal space remains normal and intact. Internal resorption starts inside the pulp space and expands outward, so the canal lumen itself enlarges or “balloons” on the radiograph while the external root outline stays comparatively intact. Because of this, an external lesion shows a radiolucency at the root surface with an unchanged canal, whereas an internal lesion shows widening of the canal space. In practice, changing the radiographic angle can help confirm: internal resorption stays centered in the canal, external resorption shifts with the tooth and lies external to the canal.