(1) to determine the success rate of retreatment and identify factors that might influence the prognosis.
(2) to obtain data on the composition of the microbial flora in previously root-filled teeth with persisting periapical lesions.
N= 54 teeth (5 with 2 canals and 49 with single canal).
Inclusion: teeth that had been previously RCT 4 to 5 years ago, asymptomatic, and showed radiographic evidence of periapical lesions.
• Rubber dam was applied and the teeth surfaces were disinfected before access.
• Access prepared, Gutta-percha removed mechanichally without use of chemical solvent & irrigation done by saline.
• The canals were left empty and the accesses were sealed with temporary filling.
• Three bacterial samples were taken by soaking up the fluid (liquid thioglycolate medium) in the canals with paper points.(1) after removal of GP (2) at a 2nd visit 7 days later (3) at a 3rd visit after 7 days of CaOH2 medicament.
• Patients were recalled yearly and up to 5 years if complete healing had not taken place earlier.
Most highlighted Results:
- The microbial flora that recovered was mainly single species of predominantly gram-positive organisms.
- The isolates most commonly recovered were bacteria of the species E.faecalis (38% of the cases with recovered bacteria).
- The overall success rate of re-treatment was 74% . In the cases from which E. faecalis was isolated,it was lower: 66%.
- Two factors had a negative influence on the prognosis: presence of bacteria at the time of root filling (+ve 3rd sample): 33% vs. 80% for -ve 3rd sample and the size of PA lesion.
E. faecalis was the most frequently detected bacteria in re-treatment cases and appears to be highly resistant to antibacterial effect of irrigants and intracanal medicaments commonly used.