Ecological approaches to periodontal therapy

Periodontitis is associated with dysbiosis of the subgingival microbiome. Prior to and as the disease progresses, there is a shift in the community structure with an overgrowth of species with certain pathogenic properties and a change in the expression of virulence attributes by the whole community. Dysbiosis is driven by the ecological relationships of microorganisms with one another and their interactions with the environment. In particular, interspecies metabolic interactions and host inflammatory products play a role in promoting microbiome shifts. A better understanding of the ecological events that lead to and sustain dysbiosis could result in novel therapeutics to restore a health-like community. Several strategies to modify the host response, which could result in reversal of microbiome dysbiotic shifts, are under development. This chapter discusses ecological strategies aimed at preventing or reversing subgingival dysbiosis by manipulating the community composition, including prebiotics, probiotics, and whole and targeted microbiome manipulations. From these, the only clinically tested strategy is probiotics, which have been shown to have a positive but small effect in selected clinical and microbiological outcomes when used as adjuncts to mechanical periodontal therapy. Other approaches such as prebiotics, inoculation with beneficial species, or targeted killing of pathogens are currently under investigation. Further research is needed to find efficient ecology-based strategies to manipulate subgingival communities that could serve as a complement to mechanical and anti-inflammatory therapies for periodontitis.