Abstract: Objective　To evaluate the antibacterial activity of nHA-PA66 on the predominant bacteria of infected root canalin vitro.Methods　Agar diffusion method was the testing method.Porphyromonas gingivalis(P.gingivalis),Fusobacteria nuclea- tum(F.nucleatum) andPrevotalla intermedius(P.intermedius) were the tested bacteria. The powder and polymerized film of nHA-PA66 were the testmateialswhile the CCQ and filter paper as the control.Results　nHA-PA66′s powder showed good ante- bacterial effect on theP.gingivalisandP.intermedius, its filmwasweaker. Both of them had no effect onF.nucleatum.Con- clusion　nHA-PA66′s antibacterial effect was not ideal, for better clinical results, some additives can be included.

Key words: antibacterial activity, nHA-PA66, predominant bacterial, infected root canal