RADICULAR CYST AFFECTING A ROOT-FILLED HUMAN TOOTH - A LONG-TERM POSTTREATMENT FOLLOW-UP

Apical periodontitis is caused primarily by microorganisms residing in the root canals of affected teeth. Nevertheless, there is convincing evidence implicating other independent factors that adversely affect t he outcome of conventional root canal therapy. In this paper, morpholo gical evidence is presented in support of the potential role of two en dogenous factors that may interfere with post-endodontic healing of th e periapex. The specimens consisted of a surgical biopsy of an asympto matic periapical lesion which persisted for a follow-up period of 44 m onths. The biopsy was processed for correlated light and electron micr oscopy. The lesion was characterized by the presence of a large centra l lumen lined by a stratified squamous epithelium. The most striking f eature of the lesion was the presence of vast numbers of cholesterol c rystals which congregated in the connective tissue surrounding the cys t cavity. Extensive light and electron microscopic investigation of th e apical part of the root canal and the lesion failed to reveal the pr esence of microorganisms. These findings strongly suggest that intrins ic factors like the accumulation of certain tissue break-down products such as cholesterol crystals, and the cystic condition of the lesion itself, can adversely affect the healing process of the periapex follo wing root canal therapy. Consequently, such apical lesions can remain refractory to conventional endodontic therapy for long periods of time .