During the last decade an increased interest in alternative, preventive, and therapeutic strategies in dentistry has arisen. Probiotics are living microorganisms which, if administered in sufficient amounts, provide a health benefit to the host. Their precise mechanisms of action have not been identified, but they are able to interfere with the imbalance occurring in biofilm-associated infections. In other fields of medicine, mainly in gastroenterology, their usefulness is already proven. Concerning oral threats, probiotic bacteria may reduce the numbers of pathogens associated with dental caries (mutans streptococci). Clinically, results are encouraging, but further research is needed to demonstrate apparent effects of certain probiotic strains on oral health as well as their desired concentration and vehicle. The use of probiotics in prevention and treatment of caries, periodontal diseases, halitosis, and other oral diseases needs to be further investigated. Keywords: caries, periodontal disease, probiotics, tooth decay