Introduction: To assess and compare the anti-microbial efficacy of ten herbal extracts against primary plaque colonizers. Materials and Methods: The branches of 10 plants with ethno-pharmacological background were collected and healthy leaves separated to prepare the fine powder. The extraction procedure was carried out by cold infusion method using ethanol. The working concentration of the extract (100 mg/ml) was prepared by mixing dried leaf extract with dimethyl sulfoxide (DMSO). 0.2% chlorhexidine and DMSO were used as positive and negative controls, respectively. Agar well diffusion method was used for anti-microbial efficacy testing. The statistical analysis was done using SPSS 16. The mean diameter of inhibition zone between the categories was compared using one-way analysis of variance and Tukey’s post-hoc test. Results: The highest mean diameter of inhibition zone against Streptococcus mutans was produced by Acacia nilotica followed by Psidium guajava, Eucalyptus hybrid and Murraya koenigii L.S extracts in the descending order. The highest mean inhibition zone against Streptococcus sanguinis was produced by chlorhexidine followed by A. nilotica, Eucalyptus, P. guajava, and M. koenigii L.S extracts in the descending order. The highest mean inhibition zone against Streptococcus salivarius was produced by P. guajava, followed by chlorhexidine, A. nilotica, Eucalyptus, M. koenigii L.S and Hibiscus sabdariffa L extracts in the descending order. Conclusion: P. guajava, Eucalyptus, A. nilotica, M. koenigii L.S and H. sabdariffa L have the potential to inhibit primary plaque colonizers, and they could be used as anti-plaque agents.
Key words: Acacia nilotica, Eucalyptus hybrid, Murraya koenigii L. sprengel, Psidium guajava, Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguis.