Microbiome and periodontitis: a systematic review and meta-analysis

BACKGROUND: The term microbiome signifies “the ecologicalcommunity of commensal, symbiotic, and pathogenicmicroorganisms that literally share our body space andhave been all but ignored as determinants of health and disease”(1). The association between the oral microbiome andperiodontal diseases is still unclear. The aim of the presentstudy was to perform a systematic review and meta-analysisof the existing literature to (i) identify the association betweenthe variation of the oral microbiome and periodontitis;and (ii) to estimate the risk of developing inflammation ofthe periodontal space in subjects who present a specific variationof the taxonomy of the oral microbiome.Methods: This systematic review was conducted accordingto the PRISMA statement (2) and the Cochrane Handbook forSystematic Reviews of Interventions (3). Literature searchesof free text and MeSH terms were performed by usingMedLine (PubMed) and Scopus (30th May 2017). Articlesfrom 1950 were searched using the following keywords: A)[(“oral flora” OR “oral ecosystem” OR “dental microflora”OR “microbial consortium”) AND (“periodontitis” OR “periodontalinflammation”)]; B) [(“oral flora” OR “oral ecosystem”OR “dental microflora” OR “microbial consortium”)].The search strategy identified 275 potential articles, 99 fromPubmed and 176 from Scopus. After removal of duplicates,170 articles were analyzed. Subsequently, 146 papers wereexcluded because they did not meet the inclusion criteria.Of the remaining 24 papers, 7 were excluded because notrelevant to the subject of the study. The remaining 17 paperswere included in the qualitative synthesis, and 11 of them inthe meta-analysis (Fig 1).RESULTS: 11 RCTs involving 2111 patients were included.The retrieved case-control studies evaluated the presence orabsence of different targeted pathogens. Among the microrganismsevaluated 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 tobe risk factors for the development of periodontitis, whileAggregatibacter actinomycetemcomitans [OR (95% CI) 0.52(0.33-0.83)] played a protective role for periodontitis.Conclusions: Our results show that Porphyromonas gengivalisand Streptococcus mutans were found to be associatedwith an increased risk for the development of periodontitis,while Aggregatibacter actinomycetemcomitans was found tobe protective for periodontitis. Better understanding of therelationship between oral microflora composition and hostoral and systemic conditions (plaque, calculus, oral hygienebehaviors, smoking) in health and disease can be of value todevelop new diagnostic and therapeutic tools, which could beoriented toward a more topic or holistic approach.