RESUMO
Bacterial cells in the human body outnumber human cells by a ratio of 10:1. Apart from their well-known pathogenic potential, bacteria are proving to be integral to the overall health of the body. Residential microbes have critical roles in diverse processes, such as nutrient harvesting, internal environment regulation, immune system development, neurological modulation, and drug metabolism, as well as providing protection against pathogens. There is a growing body of research on the microbiome and probiotic therapies to restore or augment these functions throughout the body. In particular, increasing numbers of bacterial species and bacterial interactions have been discovered in the oral cavity, and probiotic interventions for common dental problems such as caries, periodontal diseases, and oral malodor are being developed and reviewed.