Assessing Evidence to Include Filifactor alocis as a Novel Candidate in Socransky's Complexes

Socransky's complexes have identified a range of bacteria as key contributors to the onset and progression of periodontal disease. However, advancements in microbiological detection methods have allowed for exploration of the microbiome in periodontal health/disease in greater detail. In recent years, Filifactor alocis has emerged as a potential periodontal pathogen. Therefore, the aim of this review was to investigate whether this bacterium could be included in Socransky's model by summarizing the available evidence. A comprehensive literature search performed using PubMed, ScienceDirect, and Scopus databases was undertaken. The retrieved articles were filtered according to defined eligibility criteria, which yielded 24 studies. Data were extracted from these observational and clinical studies to synthesize findings. Findings regarding the host immune response were derived from in vitro and experimental animal models and narratively summarized. Observational studies and clinical trials showed heterogeneity and a lack of standardized outcomes. However, the general trend indicated a higher prevalence of F. alocis at diseased sites than at healthy sites. In addition, periodontal treatment was found to significantly reduce F. alocis levels and was associated with improvements in clinical periodontal parameters. Experimental models and in vitro studies showed that F. alocis exhibits a range of virulence attributes and pathogenic behavior similar to that of putative pathogenic periodontal bacteria. The evidence is not sufficient to include F. alocis as a new member of Socransky's model. However, this review suggests that this bacterium has the potential to be included in Socransky's complexes in the future after further research which would require to be highly standardized to enhance comparability and generalizability of findings.