Microbial cultures have been used for thousands of years in food and alcoholic fermentations, and in the past century have been investigated for their ability to prevent and cure a variety of diseases. This has lead to the coining of the term probiotics, or “pro-life”. Endorsed by the Food and Agriculture Organization and the World Health Organization. Considering the particular activities of probiotics and their inhibitory effect on the growth of pathogens, research interest has been extended to the oral cavity where probiotics may also exert their therapeutic or preventive effect on the development and progression of common oral disease. Within the limits of this systematic review it can be concluded that although existing evidence suggest that probiotics may have certain therapeutic value in treating periodontal disease, this field is in its infancy and more clinical and basic science research is needed.