A systematic review of the microbiota composition in various peri-implant conditions: data from 16S rRNA gene sequencing.

Abstract Objective To systematically review the literature regarding the microbiota composition in various peri-implant conditions as analyzed by 16S rRNA gene sequencing methods. Methods Electronic searches were conducted at MEDLINE/PubMed, Scopus, Embase, ScienceDirect and Web of Science databases looking for articles published up to April 2020. Observational prospective investigations were considered with systemically healthy patients and that had presented the description of the microbiota composition of peri-implantitis (PI), peri-implant mucositis (PM) and/or health implants (HI) by using 16S rRNA gene sequencing analysis were considered eligible. Results From 1,380 titles found, 8 studies were considered for qualitative analysis. One article was excluded due to high risk of bias, remaining 7 studies for descriptive analysis. In 6 out of 7 studies the PI microbiota was reported as being in relative abundance and variety though with a different composition from those with HI. There was no consensus regarding which condition had more diversity. The main observed phyla among PI were Firmicutes, Bacteroidetes, Actinobacteria, Fusobacteria and Spirochaetes, while the genera were mainly Actinomyces, Eubacterium, Fusobacterium, Mogibacterium, Moraxella, Treponema and Porphyromonas. Comparisons between PI and PM microbiota showed conflicting results: one study suggested that PI has greater bacterial diversity; another study reported the opposite result, while another investigation found similar variety for both conditions. Conclusions The microbiota of peri-implant conditions have been reported as distinct, although the available literature presents discrepancies. Nonetheless, considering the findings in most studies, it can be suggested that the relative abundance of microbiota and bacterial diversity increased with the progress of peri-implant disease.