Cholesterol as an aetiological agent in endodontic failures--a review.

Presence of cholesterol clefts in apical periodontitis lesions is a common histopathological observation. However, a potential aetiological association of cholesterol crystals to non-resolving apical periodontitis lesions after endodontic treatment has been suggested only recently. This article is an attempt to explain the biological basis for the inability of body cells to eliminate the local accumulation of cholesterol crystals, and to consolidate available clinical and experimental data in support of the view that massive accumulation of cholesterol crystals in inflamed periapical tissues can interfere with the periapical healing after conventional root canal treatment. As the irritating cholesterol crystals and certain other aetiological agents of failed endodontic treatment exist outside the root canal system, it is concluded that re-treatment alone, of such cases, is unlikely to resolve the factors that sustain the lesion. Apical surgery is indicated for successful management of such cases.