Internal resorption is a pathological process in which odontoclastic cells progressively destroy mineralized dentin from within the pulp chamber or root canal walls, hollowing the tooth from the inside out. Unlike external resorption, which originates at the tooth’s outer surface, this condition is driven entirely by the pulp tissue itself.
Causes and Contributing Factors
Inflammatory activation of odontoclasts — specialized cells capable of resorbing hard dental tissue — within the pulp space initiates the process. Common triggers include:
- Traumatic injury such as concussion, luxation, or avulsion
- Chronic or acute pulpitis (pulp inflammation)
- Prior pulp-capping or pulpotomy procedures
- Prolonged orthodontic force application
- Bacterial infection that has penetrated the pulp
Clinical Presentation and Diagnosis
Internal resorption is typically asymptomatic in its early stages, making routine radiographic examination the primary means of detection. On a periapical radiograph, it appears as a smooth, well-defined oval or round radiolucency that expands the root canal outline symmetrically. When the resorptive lesion progresses toward the cervical region and the overlying dentin becomes very thin, a pinkish discoloration — known as the pink tooth of Mummery — may become visible through the enamel.
In advanced cases, the resorptive cavity can perforate the root, establishing direct communication between the canal and the periodontal ligament space and significantly worsening the prognosis.
Treatment
Eliminating the vital pulp tissue is the cornerstone of management, since odontoclasts require a blood supply to remain active. Root canal therapy is the standard intervention: thorough removal of pulpal tissue halts the resorptive process. Perforated cases may require repair with biocompatible materials such as mineral trioxide aggregate (MTA), while severely compromised teeth may ultimately require extraction.
Because early-stage internal resorption produces no symptoms, consistent radiographic monitoring is the most reliable defense — identifying it before structural integrity is lost makes conservative, tooth-preserving treatment possible.