Diederik Hentenaar

174 Addendum invited to participate in the surgical follow-up study described in chapter 4 . During a resective surgical intervention, consisting of bone recontouring, surface debridement and mechanical decontamination and apically repositioned flap the implant surfaces of 93 implants with peri-implantitis (n=57 patients) were randomly treated with air- polishing (test) or saline-soaked cotton gauzes (control). Clinical, radiographical and microbiological parameters were recorded. Before treatment (baseline) and at 3, 6, 9 and 12 months after therapy clinical parameters were assessed. Radiographic examination took place at 3, 6 and 12 month follow-up and microbiological samples were taken at 12 months after treatment. No differences between the test and control group were found for the primary outcome BoP over 12 months of follow-up, nor for the secondary parameters Plq, PPD and MBL. Between both groups, a significant difference was found for the levels of SoP was seen. No significant effect on 8 classical periodontal pathogen levels was found from one of both therapies. At 1-year follow-up, a successful treatment outcome (PPD<5mm, max 1 out of 6 sites BoP, no suppuration and no progressive bone loss >0.5mm) was achieved for a total of 18 implants (19.2%). The randomized clinical trial presented in chapter 5 aimed to evaluate the effect of implant surface decontamination with phosphoric acid during a surgical peri- implantitis treatment on clinical, radiographical and microbiological parameters. In total 28 patients with 53 implants with peri-implantitis were treated with a resective surgical approach consisting of bone recontouring, surface debridement and chemical decontamination and apically repositioned flap. Patients were randomly allocated to decontamination with phosphoric acid 35% (test group) and saline rinsing (control group). Microbiological parameters were recorded during surgery, whereas clinical parameters were recorded before treatment (baseline) and 3 months after treatment. Implant surface decontamination with phosphoric acid 35% led to a greater immediate suppression of bacterial colony forming units on the implant surface than saline rinsing (1 minute of abundent sterile saline rinsing). Comparing microbiological samples taken from the peri-implant sulcus 3 months after surgery to pre-surgical samples, there were significantly less culture-positive implants after the decontamination procedure in the phosphoric acid group ( p = 0.042). However, between both groups no significant differences in clinical and microbiological outcomes were found. Hence, the use of phosphoric acid as implant surface decontaminant seemed to sort a similar clinical effect as saline rinsing. The aim of the prospective cohort study presented in chapter 6 was to evaluate the influence of the cervical crown contour on marginal bone loss and soft tissue health around platform-switched, posteriorly placed, two-piece (bone-level) implants. A dataset from two previously conducted studies was used to evaluate a total of 64