Clinical association of Spirochaetes and Synergistetes with peri-implantitis.

OBJECTIVES The microbial composition of peri-implantitis-associated biofilms may resemble that of periodontitis, with some distinctive differences, as identified by various conventional or molecular detection methods. Yet, the complete microbiome of peri-implantitis awaits further characterization. The present clinical study was undertaken with the aim to investigate the association of Spirochaetes, and the more recently identified phylum Synergistetes, with peri-implantitis. MATERIALS AND METHODS Submucosal biofilms were obtained from single sites of patients with peri-implantitis (n = 43) or individuals with peri-implant health (n = 41). The samples were analysed by fluorescence in situ hybridization (FISH) and epifluorescence microscopy, using 16S rRNA-based oligonucleotide probes for Synergistetes cluster A, subclusters A1 and A2, and Treponema groups I-III and IV. RESULTS Treponema group IV was barely detectable, whereas Treponema groups I-III were detected at low prevalence in health, but their prevalence and numbers were significantly increased in peri-implantitis by 48% and 2.4-log, respectively. Synergistetes cluster A was detected in half of the healthy sites, and its prevalence and numbers were significantly increased in peri-implantitis by 30% and 2.5-log, respectively. No quantitative differences were found between Synergistetes subclusters A1 and A2 numbers, as both increased by 2.8-log. Synergistetes cluster A displayed strong correlations with several clinical peri-implant parameters, but Treponema groups I-III only with probing pocket depth. CONCLUSION The present clinical cross-sectional study demonstrates that Spriochaetes of the Treponema groups I-III, but not group IV, and Synergistetes of the cluster A are highly associated with peri-implantitis. Synergistetes cluster A appears to display a stronger association with peri-implantitis than Spirochaetes.