Objectives:Early colonisation of oral surfaces by periodontal pathogens presents a significant risk factor for subsequent development of destructive disease affecting tissues that support the dentition. The aims of the present study were to establish the age-dependent relationship between sub-gingival profiles of 22 Prevotella species/phylotypes in children, adolescents and adults from an isolated Aboriginal community and, further, to use this information to identify Prevotella species that could serve as microbial risk indicators.Materials and methods:DNA isolated from sub-gingival plaque samples (three healthy sites and three inflamed/diseased sites) from adults, adolescents and children was screened for Porphyromonas gingivalis load and 22 Prevotella species/phylotypes by species-specific PCR.Results:A noticeable feature in adolescents was the marked increase in colonisation by P. gingivalis across all test sites. The mean number of Prevotella species/phylotypes colonising inflamed/diseased sub-gingival sites increased with age. Progressive partitioning of selected Prevotella species/phylotypes to healthy or inflamed/diseased sites was evident. Prevalence of Prevotella intermedia, Prevotella oral clone P4PB_24 and Prevotella oris increased significantly with age in diseased sites. Similarly, significant age-dependent increase in colonisation of healthy as well as inflamed/diseased sub-gingival sites was apparent for Prevotella oralis, Prevotella multiformis, Prevotella denticola, Prevotella strain P4P_53 and Prevotella oral clone BR014.Conclusion:Early colonisation of children by P. gingivalis, P. intermedia and Prevotella oral clone P4PB_24 provides indication of risk for subsequent development of periodontal disease.Clinical relevance:In the present study, the complexity of Prevotella species within gingival sites is explored as a basis for evaluating contribution of Prevotella species to disease.