Methods: 50 single-rooted extracted teeth with one root canal were flared using Revo-S instruments (size 25, 0.06 taper). Teeth were autoclaved and infected with a clinical isolate of E. faecalis for three days. Samples were taken using paper points to determine the presence of E. faecalis in the root canals. For the antimicrobial treatment the teeth were devided into two groups. In the first group teeth were treated using the PAD system (Aseptim Plus, SciCan, Germany), consisting of the photosensitizer Aseptim Solution, a tolonium chloride solution and the PAD light source at 635 nm and sampled with paper points. Teeth were treated with Aseptim Solution and the PAD light source for a second time and sampled. In the second group root canals were rinsed with 5 ml of 20% citric acid. After sampling with paper points, root canals were treated with Aseptim Solution and the PAD light source. Another sample was taken. Survival fractions of the samples were calculated by culturing on blood agar and counting colony-forming units.
Results: Treatment of root canals with PAD alone caused a reduction of bacterial load, resulting in a 76,6% kill of E. faecalis. A repeated PAD treatment killed 95,9% of E. faecalis. Rinsing root canals with 20% citric acid achieved a reduction of 93,7% and the combination of 20% citric acid irrigation and PAD reduced bacterial viability by 97,3%.
Conclusion: Photoactivated desinfection killed E. faecalis in human root canals. A second application of PAD leads to a more effective desinfection. PAD is not an alternative but a possible supplement to existing protocols of root canal desinfection. Disruption of the biofilm prior to PAD remain mandatory for adequate root canal desinfection. >