The effectiveness of sodium hypochlorite 2.5%, used to remove of the infected pulp endodontic flora was tested in vitro with three irrigation methods. Root canals of freshly extracted teeth infected were treated as follows: the first group was irrigated with a conventional manual syringe, the 2nd group received a passive ultrasonic irrigation (PUI) and the 3rd group was treated with Nd: YAP. A bacteriological sample was taken on each tooth before and after treatment using sterile paper points, these points were immediately placed in sterile petri dishes containing agar cooked (GSC) blood and incubated anaerobically at 37°C for 48 h. The bacteriological study was performed according to standard molecular biology. Analysis of the results was carried out with the software epi-info3.3.2.le rate is retained signifiance p<0.005. The results showed the superior efficacy of PUI and laser eradication endodontic flora compared to conventional irrigation.