Authors: Gartner AH, Mack T, Somerlott RG, Walsh LC.
Title: Differential diagnosis of internal and external root resorption.
Journal: J Endod
Date: Nov 1976
Citation: 2(11):329-34
Category: Diagnosis and Case Selection
Evidence-based Ranking: 5
Purpose/Objectives: Establish guidelines leading to a systemic approach for the differential diagnosis of internal and external root resorption.

Discussion: Apical third- early pulp death with incomplete root formation and external resorption can result in a blunted root. With incomplete root formation will see divergent walls with blunderbuss apex. External resorption will show a smaller canal with converging walls. Midroot- internal resorption will have sharp margins, most lesions are symmetrical, and uniform in density. With internal resorption the canal cannot be traced, and appears to balloon out into the lesion. External resorption lesions are not as sharp, usually with a moth eaten apperance. They are also not as symmetrical, and the canal itself can be traced through the lesions. An important tool is the mesial-buccal-distal rule in which an external lesion will shift in relation to the canal, whereas an internal lesion will not shift regardless of the angle. This rule is also useful for determining the location of an external resorption lesion. Midroot caries can also be distinguished from internal resorption using the same rules, however is more difficult with cases of midroot caries vs external resorption. Coronal- Only internal resorption can occur from the inside, external resorption and decay occur form the outside in.

AuthorÂ’s Conclusions: The methodology provides the practitioner with a guide to identify predictably the particular entity present, and establish a diagnosis, prognosis, and treatment more readily.

ReviewerÂ’s Comments: Classic paper that summarizes the diagnosis differences between external and internal resorption.