Probiotics are defined as living microorganisms which are considered to have beneficial health effect on their host when consumed in adequate amount. Regarding their advantageous role in periodontal disease, inhibition of specific periodontal pathogens and alteration of host immune response through multifactorial causes are thought to be their main working mechanisms. Reuterin and reutericyclin are two bacteriocins produced by Lactobacillus reuteri that inhibit growth of pathogenic bacteria, while bacterium also exhibits strong capacity of host tissue adherence and subsequent competition with pathogens.