Microbial ecology dynamics of peri-implantitis and implications of different surface disinfection protocols

Peri-implantitis remains one of the main complications following implant placement. This condition leads to bone loss, impaired function, and if left untreated subsequent implant failure may result. Microcosm biofilms contaminating the implant surface are considered the main aetiological factor. Different anti-infective adjunctive treatments to non-surgical and surgical interventions as well as implant surface decontaminating techniques have been proposed for the therapy of peri-implantitis. However, no single decontamination intervention has been found to be superior. Notably, due to the infective nature of peri-implantitis, it becomes plausible to focus mainly on the elimination of targeted microbial pathogens and bacterial remnants. Current treatment modalities are limited by our ability to resolve unique peri-implant microbial niches in states of health and disease and to determine early disease progression induced by microbial shifts. Therefore, it is essential to explore the microbial ecology behind peri-implantitis and to develop novel implant surface decontamination methods, which will lead to resolution of this infective disease. This was the focus of the present thesis. Firstly, a systematic review on implant outcomes in treated periodontitis patients was presented. Herein, it is confirmed that the history of periodontitis, its type and severity play a detrimental role on the development of peri-implantitis. Secondly, an in vitro model of peri-implant microenvironments in an artificial mouth system was developed. This was done in the quest for understanding multispecies bacterial populations interactions, shifts and structure within peri-implant biofilms, as well as the impact of their niche. Then, previously disinfected titanium (Ti) discs substrata were analysed and a number of decontamination treatment protocols were tested in vitro and in vivo by the study of microbial remnants, biocompatibility dynamics, histomorphometrical analyses and surface chemistry. Finally, inspired by the bacterial diversity and abundances across the peri-implant microbial ecology in states of health and disease shown in the in vitro model, the subgingival microbiomes in patients with history of treated aggressive periodontitis were examined