The role of probiotic bacteria in improving human health has been an attractive subject for researchers since the beginning of the 20(th) century. They have been used to control gastro-intestinal infections, to promote immunity and to prevent various diseases (allergies, urogenital infections, etc.). However, the use of beneficial bacteria in the field of dentistry has only recently gained interest. Investigation of the effects of probiotic bacteria on oral health has become an important research subject. These studies are still in the early stages, however results show that probiotic bacteria are effective against tooth caries, periodontal disease, oral mucosal lesions and oral malodour. This review provides information on the effects of probiotics--well-known for their effects on general health, and therefore more widely used in healthcare--on oral and dental health, in order to promote their use/prescription by physicians and patients.