Diederik Hentenaar

84 Chapter 4 present, was removed carefully with a scaler tip, and mechanical debridement of the peri-implant surface followed. According to the randomization, patients were assigned either to the test group or control group. In the test group the implant surface was treated with air-polishing (Airflow ® , using the Airflow Master Piezon ® device, EMS, Nyon, Switzerland) with erythritol-based powder containing 0.3% chlorhexidine (14μm, PLUS Powder, EMS). In the control group the implant surface was mechanically cleaned with saline-soaked cotton gauzes. In both groups, therapy was applied until the implant surface was assessed as visually clean by the surgeon followed by local application of abundant amounts of sterile saline. The angulation under which the air powder spray was applied and the working distance of the air polisher were factors that were not standardized in this study, as both factors varied according to the area being cleaned. The bone was recontoured on indication. After debridement the gingival flap was repositioned and closed with single interrupted sutures in a slightly apical position after which suprastructures were reconnected. Patients were instructed to use an antiseptic mouthwash (0.2% chlorhexidine, Orasol®, ICM Pharma Pte. Ltd., Singapore) for 2 weeks after surgery, two times daily. Two weeks after surgery, sutures were removed and patients were instructed to perform adequate self-performed peri-implant oral hygiene measures (i.e., at least twice daily use of electric toothbrush and use of interdental brushes). Assessments Clinical assessment Peri-implant assessment took place at baseline and 3, 6, 9 and 12 months after intervention. Additional full mouth periodontal charts were made at baseline and 12 months. The clinical parameters were assessed by one and the same experienced examiner (D.H.) who was blinded for group allocation. At 6 sites per tooth and implant (mesiobuccal, buccal, distobuccal, mesiolingual, lingual and distoligual) BoP, visible presence of plaque and/or plaque on probing (Plq) and SoP were binominally assessed (1 = present or 0 = not present) using a Hu-Friedy PCPUNC156 periodontal probe and Shephaerds Hook Explorer EXS23. Probing pocket depths were scored in absolute values to the nearest millimeter. A partial Vinyl Polysiloxane (VPS) impression (EXABITE™ II NDS, GC America Inc., Alsip, Illinois, US) was made of the suprastructure and buccally trimmed to be used as fixed reference point to assess the marginal peri-implant mucosa level. The distance from the mid-buccal marginal mucosa to the margin of the VPS mold was assessed using a periodontal probe at baseline and 12 months after surgery to calculate the recession. The top of the suprastructure was taken as a fixed reference point in case of an overdenture attachment system. In addition, a periodontal probe was used to assess the midbuccal width of keratinized mucosa. Midbuccal keratinized mucosa (KM) levels were assessed at baseline and 12 months. During surgery, the