A pathological process that begins within the endodontic space and produces progressive loss of dentin (and sometimes cementum) by clastic activity, creating an internal cavitation that is continuous with the root canal system.

Principle

Internal resorption requires metabolically active (vital) pulpal tissue adjacent to dentin that sustains clastic activity; loss of that vital tissue typically halts further internal resorptive progression.

Demonstration

Illustrative scenario: A patient presents with a tooth showing a well‑circumscribed radiolucency that is continuous with the root canal radiographically. Recognition of an internal resorptive lesion leads to root canal treatment to remove the vital pulpal tissue sustaining clastic cells; after removal and appropriate obturation, radiographic progression ceases and the defect can be restored or monitored.

Misapplication

Interpreting a radiographic radiolucency adjacent to a root as internal resorption when it actually represents external resorption, periapical pathology or an anatomic canal variation. The semantic error is attributing an origin within the canal when the defect originates on the external root surface or outside the endodontic space.

Consequence

If unrecognized or untreated while active, internal resorption can progress to root wall thinning, perforation, structural weakening and increased risk of tooth loss; timely endodontic removal of the sustaining pulp tissue can arrest progression and permit restoration.

Reversal

When the localized pulp tissue becomes necrotic or removed (e.g., by infection or endodontic treatment), the clastic activity that produces internal resorption usually stops; extensive perforation that already occurred may nevertheless require surgical or extraction management.

Boundary

Clearly within: a radiolucent lesion continuous with the root canal lumen produced from the canal side. Boundary case: a lesion at the cervical margin where internal and external resorption can appear similar radiographically and require advanced imaging to distinguish. Clearly outside: external cervical resorption that originates from the periodontal surface and invades inward.

Semantic Tension

Preserving pulp vitality to avoid endodontic treatment ↔ the need to remove or debulk vital pulpal tissue to stop an active internal resorptive process.

Synthesis

The defining practical insight is that the lesion’s origin inside the canal — and its dependence on vital pulpal tissue to fuel clastic cells — determines both diagnosis and that endodontic removal of that tissue is the primary means to arrest progression.