Methods: Twenty patients who have peri-implantitis and periodontitis were selected. The diagnostic criteria were exhibiting sites with probing depth ≥ 4 mm, bleeding on probing and/or suppuration and concomitant radiographic bone loss. Sub-gingival and sub-mucosal biofilm samples were taken from the deepest pocket of each site, and analyzed by the pyrosequencing of the amplicon obtained with universal primer set.
Results: A total of 386523 post-trimming 16s rRNA genes sequences (9663 on average) were used for the following microbial composition analysis. These sequences represented 386 bacterial species-level operational taxonomic units (OTUs) (at 3% divergence), 119 classified genera (79.1%) and 29 unclassified genera (20.9%) in the peri-implantitis. The 411 OTUs, 121 classified genera (77.8%) and 32 unclassified genera (22.2%) were generated in the periodontitis. The 8.5% and 3.8% of the total sequences in the peri-implantitis and periodontitis were unclassified, respectively. Both sites were dominated by the genera; Fusobacterium, Porphyromonas Treponema, Actinomyces. Of the total 175 genera, the 22 genera (Xanthomonas etc.) and 27 genera (Schlegelellaetc.) were detected only in the peri-implantitis and periodontitis, respectively. Unexpectedly, principal coordinate analysis revealed that the microbial composition of peri-implantitis was not similar to that of periodontitis within most individuals.
Conclusions: We present the first analysis of microbial composition of peri-implantitis and periodontitis in same patients by 16S rRNA genes pyrosequencing. The results indicate that the microbial composition of peri-implantitis differs from periodontitis, suggesting that approach for its treatment should be different from periodontitis and the prevention need to be carefully.