Diederik Hentenaar

56 Chapter 3 Setting and location All patients were recruited consecutively from the patient population of the Center of Dentistry and Oral Hygiene and the Department of Oral and Maxillofacial Surgery of the University Medical Center Groningen in the Netherlands. This single-center study was performed at the Department of Oral and Maxillofacial Surgery of the University Medical Center Groningen. Intervention One group of patients were treated once with an air-polisher using erythritol-based powder (grain size 14μm) containing 0.3% chlorhexidine (PLUS® powder, Electro Medical Systems (EMS), Nyon, Switzerland). The air-powder was applied subgingivally through a hand piece with a plastic nozzle (settings device: Perio, max liquid pressure 5.0 bar and 75% air-powder pressure, ≈7 bar, as recommended by the manufacturer). The nozzle contained a trilateral powder-outlet and an apical water-only spray. The other group patients were treated once with the piezoelectric ultrasonic scaler with a Polyether Ether Ketone (PEEK) coated plastic tip (PI instrument, EMS). Both interventions took place for 30 seconds per implant (5 seconds per site). Before subgingival decontamination, the implant surface was checked on hard deposits (i.e. calculus) and removed subsequently using hand instruments. The suprastructures remained fixed during the intervention and local anaesthesia was used as needed. Both groups’ treatments were preceded by a 30-second mouth rinse with 0.12% chlorhexidine + 0.05% cetylpyridinium chloride without alcohol (Perio-aid®, Dentaid). Prior to peri-implant cleaning, but during the same session, a full mouth periodontal cleaning was applied using ultrasonic and/or hand instrumentation (EMS, Nyon, Switzerland / Hu-Friedy, Chicago, Illinois, US, scalers and curettes). Additionally, all patients received extensive oral hygiene instructions during the treatment appointment, including the use of an electric toothbrush and interdental brushes with the application of 0.12% chlorhexidine gel (PerioAid® gel, Dentaid Benelux, Houten, the Netherlands). All treatments were performed by three experienced dental hygienists. Reinforcement of oral hygiene instructions and supragingival cleaning of the included implant(s), using hand instrumentation, took place at 3, 6, 9 and 12 months (by the examiner, D.H.). Outcomes Primary outcome The primary outcome was the mean percentage of peri-implant sites showing BoP at 3 month post-treatment.