Diederik Hentenaar

12 Chapter 1 For example, studies defining a threshold of marginal bone loss >5 mm yielded a prevalence of peri-implantitis of 1% (Zetterqvist et al. 2010) whereas a threshold of 0.4 mm marginal bone loss increased the prevalence of peri-implantitis to 47% (Koldsland et al. 2010). Studies in which the newly presented diagnostic 2017 World Workshop criteria were applied remain rare. However, interestingly, a research group of Shimchuk and coworkers re-evaluated their own previous used data set with the new 2017 criteria, concluded a drop in peri-implantitis at both patient and implant level of nearly 50% compared to the prior analysis (Shimchuk et al. 2020). This might suggest that prevalence rates reported in previous published literature present an overestimation of disease prevalence. However, more studies using these new criteria are needed to confirm this finding. Nevertheless, despite a lack of consensus on the prevalence, a PubMed search (up to August 2021) using the words ‘Peri-implantitis’ AND ‘Treatment’, shows an exploding number of studies over the last 30 years, indicating an increase of interest within the scientific field of research on this topic (Marcantonio Junior et al. 2019). Moreover, a general consensus under clinical experts on an expected increase of peri-implanitis prevalence up to 2030 is reported (Sanz et al. 2019). Risk factor Peri-implant diseases have been linked to a large number of potential patient and implant-related risk factors/indicators (Monje et al. 2019, Maney et al. 2020). Risk factors are causal agents of a disease which are usually confirmed by longitudinal studies, whereas risk indicators are based on cross-sectional data (Beck, 1998). There is strong evidence that the presence and history of periodontitis increases the risk for peri- implantitis and that poor oral hygiene and lack of compliance with regular maintenance therapy may play an important role (Dreyer et al. 2018). The evidence for an association with peri-implantitis remains equivocal regarding cigarette smoking and diabetes mellitus, these modifying factors are considered as potential risk indicators or emerging risk factors (Schwarz et al. 2018). In addition, bone quality, obesity, metabolic syndrome, implant surface characteristics and placement depth have also been reported to be predisposing factors for the development of peri-implantitis. Other factors that may play a role but currently not well-understood are certain medications, age, gender, low vitamin D, autoimmune diseases, amount of keratinized mucosa and peri-implant tissue-bound titanium particles (Araujo & Lindhe 2018, Delgado-Ruiz & Romanos 2018, Mombelli et al. 2018, Safioti et al. 2017). The role of genetics is still unclear, but studies show that certain polymorphisms may be associated with peri-implantitis (Laine et al. 2006). Prosthetic risk factors, such as improper restorative design, occlusal overload, microgap, and residual cement are considered significant as well (Misch et al. 2005, Dixon &