External Resorption

Definition: Resorption of the outer surface of a tooth.

Radiographic Features:

Location: Most commonly seen at the apices of teeth, but can affect any portion of a tooth that is within bone.

Edge: Well-defined, smooth outline with altered shape of the tooth.

Shape: Blunted, linear apex instead of tapered.

Internal: Radiolucent when appears over the root.

Other: When positioned over the pulp chamber and/or root canal, the outline of the chamber/canal will still be evident.

Number: May be single or multiple.

TIP: External resorption over the facial or lingual surface of a root can be difficult to determine from internal resorption.  Re-examine the radiograph to determine if the outline of the pulp chamber and/or root canal is visible.  A shift shot can help determine if the chamber/canal outline is evident and not continuous with the radiolucent area.  If the radiolucent area is continuous with the chamber/canal outline, it indicates internal resorption is more likely.

(click image to enlarge)

External resorption at apices of mandible anterior teeth

(left – with arrows) (right – without arrows)

External resorption

(blunted apices of mandibular left first molar – #19)

External resorption

(apex and over root – note root canal outline evident)

External resorption

(blunted apex of maxillary right second premolar -#4)

External resorption

(impacted maxillary right third molar – #1)