Diederik Hentenaar

156 Chapter 7 of potential cytotoxicity of nano-sized metal particles on soft tissue cells (Suárez-López Del Amo et al. 2019), biomechanical issues in terms of bending strength especially in narrow/regular diameter implants (Chan et al. 2013), influence on the implant-abutment connection designs (Gehrke et al. 2016) and implant/bone overheating (Sharon et al. 2013). Moreover, it is technically demanding and time consuming (Costa-Berenguer et al. 2018). While early detection and diagnosis of peri-implant disease is critical to prevent peri- implantitis, current diagnostic procedures (e.g. bleeding on probing) can only assess past tissue destruction and do not provide any information about disease activity or the risk on future disease progression. As such, point-of-care technologies, which recently emerge as new tools to diagnose periodontitis and peri-implantitis at chair- side, are needed to pinpoint the crucial disease transition from peri-implant health to peri-implant mucositis to peri-implantitis (Golub et al. 2020). Currently, promising results regarding the use of an active form of MMP8 point-of-care test for periodontitis have been reported (Räisänen et al. 2019, Räisänen et al. 2020). However, to evaluate the potential use of diagnostic chair-side tests in identifying the onset and progression of peri-implant diseases, much research is needed. Another promising point-of- care technology which recently appeared in the literature on dental implants is the use fluorescence spectroscopy (Andrade et al. 2021, Hwang et al. 2021). With this technology, the amount of pathogenic bacteria or their metabolic activity on the implant surface could be visualized in-situ. Hence, although much more future research is needed to confirm the potential of this technology, it might play an important role in determining whether the implant surface/area has been successfully decontaminated after treatment . At last, the studies presented in this thesis evaluated the inflammatory reaction solely around titanium dental implants. Whether the therapy outcomes also hold true for zirconia dental implants remains to be found. Currently, zirconia is increasingly being discussed in the literature as alternative for titanium implants (Cionca et al. 2017, Afrashtehfar & Del Fabbro 2020, Comisso et al. 2021). In-vitro studies have shown low affinity to bacterial plaque and some clinical studies show better soft tissue response with zirconia implants and less material corrosion, suggesting that this material could provide a protective effect against inflammation (Afrashtehfar & Del Fabbro 2020). However whether these properties lower the risk for peri-implant disease remains unknown. Thus far, only short term promising results in terms of clinical efficacy have been reported (Webber et al. 2021). The literature on peri-implantitis in patients with ceramic implants is still scarce. Hence, to gain insight in the prevalence,