IntroductionMicrobial infection plays an important role in persistent periapical lesions.1 Insufficient disinfection of root canals could lead to treatment failure and persistent periapical pathology.
2Conventional techniques of root canal treatments such as mechanical instrumentation and chemical debridement with antimicrobial irrigants, such as sodium hypochlorite (NaOCl), chlorhexidine and calcium hydroxide do not always suffice to predictably render root canals free of bacteria.3,4 Factors such as anatomical complexities, bacterial growth as biofilm, render complete disinfection of the root canal system almost impossible.
5Studies have revealed a success rate of 94% with a negative culture before obturation has decreased to 68%, with a positive culture.2 Resolution of periapical lesions is more achievable when there is negative culture before obturation.
6Cross sectional studies have reported 20%-60% of treatment failure and 52% of endodontic failure in Iranian population.7-10 Existence of intracanal microorganisms would lessen the treatment outcomes of endodontic re-treatment comparing to primary endodontic treatment.
2Based on the previous studies, bacterial microflora in teeth with failed endodontic treatment is different from the microflora of the primary endodontic infection. All culture and PCR based methods have shown that primary endodontic infection is a polymicrobial infection involving fully anaerobic microorganisms, 5,11 while the failure
AbstractIntroduction: The aim of this study was to compare the antibacterial efficacy of diode laser 810nm and photodynamic therapy (PDT) in reducing bacterial microflora in endodontic retreatment of teeth with periradicular lesion. Methods: In this in vivo clinical trial, 20 patients who needed endodontic retreatment were selected. After conventional chemo mechanical preparation of root canals, microbiological samples were taken with sterile paper point (PP), held in thioglycollate broth, and then were transferred to the microbiological lab. In the first group, PDT with methylene blue (MB) and diode laser (810 nm, 0.2 W, 40 seconds) was performed and in the second group diode laser (810 nm, 1.2 W, 30 seconds) was irradiated. Then second samples were taken from all canals. Results: CFU/ml amounts showed statistically significant reduction in both groups (P < 0.001). CFU/ml amounts were compared between the two groups and there was no statistical difference. Conclusion: PDT and diode laser 810 nm irradiation are effective methods for root canal disinfection. PDT is a suitable alternative for diode laser 810 nm irradiation, because of lower thermal risk on root dentin.