Microbes are considered as the primary etiologic agents in endodontic diseases.Disinfection of the root canal is obtained by the combined effect of biomechanicalpreparation, irrigation and intra canal medicament. The aim of the present study wasto assess the antimicrobial activity of intracanal medicaments (formocresol andEndosepton) against two micro organisms (Streptococcus mutans and staphylococcusaureus) isolated from 15 necrotic pulps of primary molars indicated for pulpectomyprocedure. The samples were cultured, and purified using microbiological evaluation.Broth dilution test was performed in our study by preparing test tubes containing10 ml of BHI broth (pH. 7) which then inoculated with strains of the tested bacteriaand incubated at 37 C° for 24 h. After over night incubaction, ten fold dilution weremade in test tubes containing 9 ml of normal saline by adding 1 ml of the inoculum tothe first tube . Then from dilution 10-1 , 0.1 ml of cell suspension was added to 9.9 mlof formocresol and endosepton, then 0.1 ml was taken and spread on duplicates ofBHI agar plates at different intervals and incubated aerobically for 24 h. at 37 C°.Colonies on the plates were counted after incubation and CFU/mL (colony formingunit) was calculated. Our results indicating that there were no significant differencesbetween the intracanal medicaments, but there were high significant differencesbetween the intervals time of the study. We concluded that both materials had greatantibacterial effect against the pathogens commonly isolated from necrotic pulpaltissue of primary teeth.
