(PR97) Quantification of Microbial Load and its Byproducts During Endodontic Retreatment of Asymptomatic Teeth Without Apparent Periapical Lesion

Endodontic retreatment (ER) is indicated for the treatment of secondary/persistent infections characterized as polymicrobial infection, evidenced by the presence of chronic apical periodontitis (CAP), and for prosthetic reasons (PR) aiming at apical repair and greater longevity of the rehabilitation treatment. The study aimed to: a) Review microbial profiles of root canals (RC) indicated to ER due to CAP and PR; b) Evaluate the effectiveness of chemical-mechanical preparation (CMP) and the use of intracanal medication (ICM) in the decontamination of RC; c) Correlate the profile and microbial load to clinical aspects. Samples were obtained from 15 teeth indicated for ER due to CAP and 15 teeth indicated for PR. Collections were performed after deobturation, after CMP, and after using ICM for 30 days. The presence of 17 bacterial species was evaluated by Nested-PCR. The effectiveness of the ER was monitored by the CFU count. Statistical tests were applied. Bacteria were detected in 100% of the initial collections. E. faecalis, F. nucleatum, P. gingivalis were the most prevalent species in both groups. ER reduced the microbial load in both groups (p < 0.05). Significant associations between bacteria and clinical signs and symptoms were found (p < 0.05). It was concluded that the community present in the RC of the teeth indicated for ER is mixed and heterogeneous. The microbial load of RC with CAP is higher than that of RC without CAP. RE is effective in decontaminating the RC. There are associations between specific bacteria and clinical features.