Diederik Hentenaar

112 Chapter 5 etching gel (pH 1). According to An et al. (2012), acid-etching of the implant surface might positively influence the epithelial seal around dental implants, as shown in their in-vitro study. In addition, animal studies (Kolonidis et al. 2003, Alhag et al. 2008) showed re- osseointegration and direct bone-to-implant contact when acids were used. Therefore, phosphoric acids might be considered a potentially feasible decontaminating agent. Thus far, the use of phosphoric acid etching gel as decontaminating agent has not been evaluated in a randomized controlled trial. The aim of the present randomized controlled trial is to evaluate the short-termmicrobiological and clinical effectiveness of 35% phosphoric etching gel as a decontaminating agent of the implant surface during resective surgical treatment of peri-implantitis. METHODS Trial design The present study is a double-blind randomized controlled trial evaluating the effect of 35% phosphoric etching gel (test group) compared to the effect of saline (control group) for implant surface decontamination combined with mechanical debridement during surgical peri-implantitis treatment. Patients were randomly assigned to the test or control group using a one-to-one allocation ratio. The study has been conducted in full accordance with the World Medical Association Declaration of Helsinki (version 2008) and was approved by the Institutional Review Board of the University Medical Center Groningen, the Netherlands (METc2013.005). Written informed consent was obtained from all participants before entering the trial. Clinical trial registration was done at the Netherlands National Trial Register (www.trialregister.nl , trial number NTR5185). The CONSORT guidelines for reporting a clinical trial were followed. Participants Patients participating in this study were consecutively selected from the patient populations of the Center of Dentistry and Oral Hygiene and the Department of Oral and Maxillofacial Surgery of the University Medical Center Groningen, Groningen, The Netherlands from October 2012 to April 2014. Adult patients with at least one endosseous implant with clinical and radiographical signs of peri-implantitis were included. Peri-implantitis was defined as a loss of marginal bone ≥ 2 mm in combination with bleeding and/or suppuration on probing and a peri-implant probing depth ≥ 5 mm (De Waal et al. 2015). Implants had to be in function for at least two years.