Microbiome and periodontitis: a systematic review and meta-analysis

BACKGROUND: The term microbiome signifies “the ecological community of commensal, symbiotic, and pathogenic microorganisms that literally share our body space and have been all but ignored as determinants of health and disease” (1). The association between the oral microbiome and periodontal diseases is still unclear. The aim of the present study was to perform a systematic review and meta-analysis of the existing literature to (i) identify the association between the variation of the oral microbiome and periodontitis; and (ii) to estimate the risk of developing inflammation of the periodontal space in subjects who present a specific variation of the taxonomy of the oral microbiome. Methods: This systematic review was conducted according to the PRISMA statement (2) and the Cochrane Handbook for Systematic Reviews of Interventions (3). Literature searches of free text and MeSH terms were performed by using MedLine (PubMed) and Scopus (30th May 2017). Articles from 1950 were searched using the following keywords: A) [(“oral flora” OR “oral ecosystem” OR “dental microflora” OR “microbial consortium”) AND (“periodontitis” OR “periodontal inflammation”)]; B) [(“oral flora” OR “oral ecosystem” OR “dental microflora” OR “microbial consortium”)]. The search strategy identified 275 potential articles, 99 from Pubmed and 176 from Scopus. After removal of duplicates, 170 articles were analyzed. Subsequently, 146 papers were excluded because they did not meet the inclusion criteria. Of the remaining 24 papers, 7 were excluded because not relevant to the subject of the study. The remaining 17 papers were included in the qualitative synthesis, and 11 of them in the meta-analysis (Fig 1). RESULTS: 11 RCTs involving 2111 patients were included. The retrieved case-control studies evaluated the presence or absence of different targeted pathogens. Among the microrganisms evaluated Porphyromonas gengivalis [OR (95% CI) 2.93(0.98,8.87); P< 0.0001] and Streptococcus mutans [OR (95% CI) 1.77 (0.89-3.54); P=0.03] were found to be risk factors for the development of periodontitis, while Aggregatibacter actinomycetemcomitans [OR (95% CI) 0.52 (0.33-0.83)] played a protective role for periodontitis. Conclusions: Our results show that Porphyromonas gengivalis and Streptococcus mutans were found to be associated with an increased risk for the development of periodontitis, while Aggregatibacter actinomycetemcomitans was found to be protective for periodontitis. Better understanding of the relationship between oral microflora composition and host oral and systemic conditions (plaque, calculus, oral hygiene behaviors, smoking) in health and disease can be of value to develop new diagnostic and therapeutic tools, which could be oriented toward a more topic or holistic approach.