Post-treatment Apical Periodontitis: Histobacteriologic and Histopathologic Findings

Occurrence of post-treatment apical periodontitis characterizes the failure of endodontic treatment. This study described the histobacteriologic and histopathologic features of biopsy specimens of teeth with post-treatment apical periodontitis.

The material comprised sequential biopsy specimens of 71 human root canal-treated teeth with apical periodontitis. Specimens were obtained by apical surgery or extraction and consisted of root apexes with attached lesions, which were processed for histobacteriologic and histopathologic evaluation of the cause of failure, infection distribution, and the type of lesion. Different aspects of infection were evaluated for associations with demographic, clinical, radiographic and histopathologic parameters.

Intraradicular bacteria were found in the apical root canal system of 94% of the specimens, often organized in biofilm structures (79% of the cases). Infection extended to dentinal tubules and ramifications in many cases. The occurrence of biofilms in the main apical canal lumen was significantly more frequent in teeth with underfillings and inadequate root canal treatment (P < .05). An extraradicular infection occurred in 37% of the cases; in all but one case, it was associated with an intraradicular infection. Extraradicular bacteria were observed as a biofilm (sometimes with calcification foci) attached to the outer root surface and as planktonic cells or flocs at the lesion body or in the cyst lumen. Extraradicular infection was significantly more present in cases with symptoms and sinus tracts, abscesses, large lesions, and retreatment (P < .05). Nonepithelialized granuloma was the most frequent type of post-treatment apical periodontitis (42%).

Intraradicular infection was the major factor associated with post-treatment apical periodontitis. Extraradicular infection was observed in about one-third of the cases, and in the large majority of them associated with concomitant intraradicular infection. Granuloma was the most common histopathologic diagnosis of posttreatment lesions.