Diederik Hentenaar

44 Chapter 2 Biomarker levels in PICF before and after therapy As far as we know, only two studies assessed the influence of non-surgical peri- implantitis therapy on markers in the PICF of peri-implantitis sites (Basetti et al. 2014, Renvert et al. 2016). Our study seems in accordance with study by Renvert et al. (2016) who neither found any differences in the majority of the studied cytokines (6 out of 9). A clinically stable treatment outcome was found in their study in only 22% of the cases at 6 months after therapy, using a single intervention with either an air- abrasive device or Er:YAG laser. Our study noticed a similar limited clinical effect, with persisting signs of inflammation (±50% of patients showing BoP and unchanged levels of SoP) 3 months after non-surgical peri-implantitis treatment and unchanged levels for the majority of biomarkers. In contrast, Basetti et al. (2014) found lower levels of IL-1β and MMP-8 at 3 months after therapy. However, additional delivery of local minocycline microspheres to the mechanical debridement with titanium curettes and glycine powder air-polishing was applied in their study. Hence, this could have led to a suppressed immune response with subsequently lower biomarker levels after therapy. Considering that the non-surgical therapy seemed unsuccessful, it might be speculated that clinical and radiographical parameters after non-surgical therapy are immunologically underlined. However, with our study, it seems not possible to truly support or deny the potential use of a change in biomarker as a monitor to assess the effectiveness of a peri-implantitis treatment with PICF analysis. Limitations of the study and future recommendations Interpreting the findings of this study, the following limitations should be kept in mind. Due to the limited sample size, no sub-analyses could be performed for several possible confounding factors (e.g., smoking, age, sex). Therefore, interpretation of our results with previous studies should be done with caution. Although an association between elevated inflammatory biomarkers levels (such as interleukin-1β, interleukin-6, interleukin-10, and tumor necrosis factor-α) in the PICF and smoking is described, (Tatli et al. 2013, Ata-Ali et al. 2016), no differences in smoking prevalence between the healthy control and peri-implantitis subjects in this study was seen. Therefore, interference of smoking with our analysis was not assumed. A minor drawback of the study might be the difference in therapies applied. We used the Airflow Master Piezon ® to either apply air-polishing or ultrasonic therapy. Considering the limited effect of non-surgical peri-implantitis interventions in general, as well as the limited effect observed in our study, the influence of therapy difference on immunological markers was considered rather low.