Analysis of P.gingivalis, T.forsythia and S.aureus levels in edentulous mouths prior to and 6months after placement of one-piece zirconia and titanium implants

BackgroundIt has been suggested that completely edentulous patients harbour fewer periodontopathic bacteria compared with dentate patients, due to the removal of the subgingival periodontal environment. However, reappearance of certain microbes has been reported after the placement of implants in these patients. AimThe aim of this study was to determine whether the periodontopathic bacteria Porphyromonas gingivalis and Tannerella forsythia, as well as the non-periodontopathic bacterium, Staphylococcus aureus, emerged in edentulous patients 6months after placement of one-piece zirconia and titanium implants. Materials and methodsTwenty-six patients were included in the study (titanium=13, zirconia=13). Microbial samples were collected from the tongue prior to implant placement and 6months after implant placement from both the tongue and from around the implants. A qRT-PCR assay using SYBR green/ROX chemistry was used for the detection and quantification of rgp, nuc and karilysin single-copy gene of P.gingivalis, T.forsythia and S.aureus, respectively. Positive controls used in the study were pure bacterial gDNA purified from cultures of P.gingivalis and S.aureus, a cloned sequence of the karilysin gene for T.forsythia, a plaque sample positive for P.gingivalis and T.forsythia, and nasal gDNA for S.aureus. ResultsThe results show that prior to implant placement, all three bacterial species were below the lower limit of quantification in all edentulous patients. The samples collected from the tongue and around the implants remained below the lower limit of quantification for each of the three species. However, all positive controls used in the study were detectable in the samples. qPCR standard curves showed correlation coefficients >0.97 and efficiencies >94.5% (slope range -3.19 to -3.46) for each of the SYBR green PCR assays. ConclusionThe results of this study indicate that the tested organisms did not emerge 6months after implant placement irrespective of the nature of the implant biomaterial. A further follow-up of at least 2years post-implantation of these patients is suggested to determine whether there are any changes in the oral microbiota and whether such changes are associated with the development of peri-implant disease.