Diederik Hentenaar

153 General discussion and conclusions Adjunctive use of antibiotics From the literature on the treatment of periodontitis, full-mouth ecological change (suppression of periodontal pathogens and recolonization of the biofilm by host- compatible species) was found to be necessary to re-establish periodontal health (Feres et al. 2015). Hence, one might advocate the use of local and/or systemic antibiotics in the treatment of peri-implantitis. Although our studies were conducted to evaluate solely the effect of the decontaminating agent, different local and systemic antibiotic applications have previously been investigated (van Winkelhoff 2012). Recent randomized clinical trials evaluating the use of systemic amoxicillin plus metronidazole showed no improvement in clinical and microbiological outcomes after non-surgical peri-implantitis treatment (Shibli et al. 2019, de Waal et al. 2021). It was suggested that, as compared to planktonic bacteria, bacteria in (undisturbed) biofilms display an increased tolerance to antimicrobial agents (Stewart et al. 2015), and hence may cause adjunctive systemic antibiotics to be less effective. It therefore seems unlikely that the lack of antibiotics could have impacted the results found in the study presented in chapter 3 . On the other hand, positive results of local minocycline use in the surgical treatment of peri-implantitis have been described (Cha et al. 2019). The repeated local delivery of minocycline showed significant benefits in terms of clinical parameters and radiographic bone fill, with a higher treatment success rate in the short healing period (6 months). In addition, the use of systemic antibiotics in the surgical treatment of peri-implantitis showed beneficial effects, especially in implants with non-modified surfaces (Carcuac et al. 2016). Although the implant surface characteristics seem to have a significant impact on 3-year outcomes, benefits of systemic antibiotics were limited to the first year of follow-up (Carcuac et al. 2017). Therefore, up to date, long term clinical efficacy of antibiotics in the treatment of peri-implantitis are lacking. Moreover, it remains unclear which patient characteristics are indicative for a beneficial systemic or local antimicrobial treatment. Modifying iatrogenic factors In order for a peri-implantitis treatment to be successful, local predisposing factors with a potential negative impact on the treatment outcome should be identified, and modified if possible before initiating an intervention (Monje et al. 2018). Such factors include for example: cement remnants, implant malpositioning and loose or improper fit of the prosthetic reconstruction. Additionally, the design of the implant supported suprastructure is considered an important factor which should allow patients to perform an optimal level of self-care. This factor was highlighted in a study by Serino and Strom (2009), in which a high proportion of implants with peri-implantitis were associated found to be associated with no accessibility/capability for appropriate oral hygiene measures. However, to date, little is known on how to design the optimal 7