05/08/2026
Internal Root Resorption is still not completely understood, but clinicians are identifying it more frequently now — likely because of better imaging, especially with CBCT scans, and increased awareness among dentists and endodontists.
Current understanding suggests it usually begins after chronic inflammation or trauma damages the protective layer inside the pulp chamber/root canal. Once that barrier is disrupted, clastic cells can start resorbing the dentin from the inside of the tooth outward.
Internal Resorption ⬇️
▶️ Definition
➟ A progressive, destructive process of intraradicular dentin that begins from within the root canal wall.
➟ It is caused by multinucleated dentinoclasts or odontoclasts acting on the internal dentin surface.
▶️ Etiology Causes
➟ Most common cause is dental trauma.
➟ Other causes include deep caries, excessive heat during restorative procedures, and orthodontic tooth movement.
➟ Crucial board fact: Internal resorption requires a vital, vascular pulp below the lesion to supply clastic cells with blood and nutrients.
➟ If the pulp becomes completely necrotic, internal resorption stops.
▶️ Key Clinical Symptoms High-Yield
➟ Usually asymptomatic and often discovered incidentally on routine radiographs.
➟ Pink tooth of Mummery may be seen if the lesion is in the coronal pulp chamber.
➟ The pink color occurs because highly vascular inflamed granulation tissue shines through thinned enamel and dentin.
▶️ Radiographic Findings High-Yield
➟ Smooth, well-defined, symmetrical ballooning or oval radiolucent enlargement of the root canal space.
➟ The original root canal outline is lost or distorted at the site of the lesion.
➟ The lesion usually stays centered in the canal on angled radiographs because it is located inside the canal.
▶️ Complications
➟ If untreated, the resorptive defect may progress through dentin and cementum.
➟ This can cause intraosseous root perforation.
➟ Perforation makes the tooth much harder to save and lowers the prognosis.
▶️ Treatment & Prognosis
➟ Definitive treatment is prompt root canal therapy.
➟ Removing the vital pulp cuts off blood supply to odontoclasts and stops the resorptive process.
➟ Warm vertical condensation or thermoplasticized gutta-percha may be needed to fill the ballooned, irregular defect.
➟ Prognosis is excellent if treated before perforation.
➟ Prognosis becomes poor or questionable if a large perforation has already occurred.
❇️ Board Exam Differentiator
➟ Internal resorption: Canal outline bulges and is lost within the defect.
➟ External resorption: Canal outline can still be traced through the radiolucent lesion.