Dental plaque-related diseases (cavities, gingivitis, periodontitis and halitosis) have been traditionally controlled by mechanical non-specific removal of plaque. However, many novel treatment approaches aim to inhibit the growth of pathogenic bacteria or to remove their toxins. Probiotics are viable microorganisms which, when administered in adequate amounts, provide a health benefit to the host. Recently, probiotics have been applied as new tools for the improvement of dental health. They have been used to substitute existing antibiotic treatments due to increased resistant bacteria. Probiotics not only have antibacterial activity, but they also have inhibitory effects on the reappearance of oral pathogenic bacteria. The aim of this study was to assess the clinical effect of the administration of probiotics agents in the treatment of mild to moderate periodontitis.