Influence of infection at the time of root filling on the outcome of endodontic treatment of teeth with apical periodontitis

TLDR

One‑visit endodontic treatment cannot reliably eradicate all infection from the root canal without an inter‑appointment antimicrobial dressing. This study examined whether infection status at the time of root filling predicts the long‑term prognosis of endodontic therapy. The authors instrumented and irrigated 55 single‑rooted teeth with apical periodontitis, obtained post‑instrumentation anaerobic samples, root‑filled the canals in the same appointment, and monitored periapical healing over five years. All teeth were initially infected; after instrumentation only 22 of 55 canals had low bacterial counts, and complete periapical healing occurred in 94% of cases with negative cultures versus 68% when cultures remained positive, highlighting the importance of eliminating bacteria before obturation.

Abstract

Summary This study investigated the role of infection on the prognosis of endodontic therapy by following‐up teeth that had had their canals cleaned and obturated during a single appointment. The root canals of 55 single‐rooted teeth with apical periodontitis were thoroughly instrumented and irrigated with sodium hypochlorite solution. Using advanced anaerobic bacteriological techniques, post–instrumentation samples were taken and the teeth were then root‐filled during the same appointment. All teeth were initially infected; after instrumentation low numbers of bacteria were detected in 22 of 55 root canals. Periapical healing was followed up for 5 years. Complete periapical healing occurred in 94% of cases that yielded a negative culture. Where the samples were positive prior to root filling, the success rate of treatment was just 68%– a statistically significant difference. Further investigation of three failures revealed the presence of Actinomyces species in each case; no other specific bacteria were implicated in failure cases. These findings emphasize the importance of completely eliminating bacteria from the root canal system before obturation. This objective cannot be reliably achieved in a one‐visit treatment because it is not possible to eradicate all infection from the root canal without the support of an inter–appointment antimicrobial dressing.