Has the use of molecular methods for the characterization of the human oral microbiome changed our understanding of the role of bacteria in the pathogenesis of periodontal disease?

P>Background Only around half of oral bacteria can be grown in the laboratory using conventional culture methods. Molecular methods based on 16S rRNA gene sequence are now available and are being used to characterize the periodontal microbiota in its entirety. Aim This review describes the cultural characterization of the oral and periodontal microbiotas and explores the influence of the additional data now available from culture-independent molecular analyses on current thinking on the role of bacteria in periodontitis. Results Culture-independent molecular analysis of the periodontal microbiota has shown it to be far more diverse than previously thought. A number of species including some that have yet to be cultured are as strongly associated with disease as those organisms traditionally regarded as periodontal pathogens. Sequencing of bacterial genomes has revealed a high degree of intra-specific genetic diversity. Conclusions The use of molecular methods for the characterization of the periodontal microbiome has greatly expanded the range of bacterial species known to colonize this habitat. Understanding the interactions between the human host and its commensal bacterial community at the functional level is a priority.