Bacterial competitiveness appears to be an efficient way to fight pathogenic oral flora. This competition may befacilitated by probiotics, particularly in periodontal diseases. The aim of this study was to investigate the probioticproperties of 61 clinical isolates of oral lactobacilli.The inhibitory activity of the tested strains against periodontopathogens was assessed with the agar overlaytechnique. The results obtained, as well as those resulting from previous work, led us to select the nine mostpromising strains on which we conducted further tests, such as evaluating their coaggregation capacities withvarious oral species and the production of proinflammatory cytokines by PBMC. We also evaluated the safety of theprobiotics by assessing their sensitivity to antibiotics. Their possible involvement in halitosis was investigated bytesting their ability to produce volatile sulfur compounds.The results of the agar overlay technique showed that all the lactobacilli strains had an antibacterial activityagainst Tannerella forsythia, Treponema denticola, and Aggregatibacter actinomycetemcomitans. Fifty-two strainsslightly inhibited the growth of P. gingivalis and only two had no activity on F. nucleatum. The nine strains tested didnot coaggregate with P. gingivalis, T. forsythia, T. denticola or A. actinomycetemcomitans. Three strains stronglycoaggregated with F. nucleatum. Only three strains produced lower IL-6 than the activator at the maximumconcentration tested in this study. However, none of the 9 strains produced a greater amount of IL-8 than thatobtained with 1 μg/ml of LPS. These results show us that all the strains were sensitive to the antibiotics tested,except for one strain which showed resistance to penicillin. The production of CSV by the strains remained belowthe threshold of halitosis. Among the 61 strains tested, 9 proved to be of interest including one that was particularly promising.< Réduire