Shift of microbial composition of peri-implantitis-associated oral biofilm as revealed by 16S rRNA gene cloning.

PURPOSE: Micro-organisms are important triggers of peri-implant inflammation and analysing their diversity is necessary for peri-implantitis treatment. This study aimed to analyse and compare the microbiota associated with individuals with peri-implantitis, as well as clinically healthy implant sites.

METHODOLOGY: Subgingival biofilm samples were taken from 10 individuals with peri-implantitis and from at least 1 clinically healthy implant. DNA was extracted and bacterial 16S rRNA genes were amplified using universal primers. After cloning the PCR-products, amplified inserts of positive clones were digested using restriction endonucleases, and the chosen clones were sequenced. The 16S rDNA-sequences were compared to those from the public sequence databases GenBank, EMBL and DDBJ to determine the corresponding taxa.

RESULTS: Differing distributions of taxa belonging to the phyla Firmicutes, Bacteroidetes, Fusobacteria, Actinobacteria, Proteobacteria, Synergistetes, Spirochaetae and TM 7 were detected in both the healthy implant (HI) and the peri-implantitis (PI) groups. A significantly higher relative abundance of phylum Bacteroidetes, as well as of the species Fusobacterium nucleatum, were found in the PI group (P<0.05). The putative periodontal red complex (Porphyromonas gingivalis, Tannerella forsythia) was also detected at significantly higher levels in the PI group (P<0.05), whereas the yellow group, as well as the species Veillonella dispar, tended to be associated with the HI group.

CONCLUSION: A shift in the healthy subgingival microbiota was shown in peri-implantitis-associated biofilm. Anaerobic Gram-negative periopathogens, including P. gingivalis and T. forsythia, seem to play an important role in peri-implantitis development and should be considered in treatment and prevention strategies.