Diederik Hentenaar

55 Erythritol air-polishing in non-surgical peri-implantits treatment MATERIALS AND METHODS Trial design This two-armed, parallel, investigator-blinded randomized controlled trial was the first of a two-staged peri-implantitis treatment approach consisting of (1) a single non-surgical treatment and (2) a surgical follow-up treatment if signs of peri-implantitis persisted at the 3-month evaluation after the non-surgical treatment. Patients with a successful treatment outcome at the 3-month evaluation (i.e., probing pocket depth (PPD) < 5mm, no bleeding / suppuration on probing (BoP) / (SoP) and no progressive marginal bone loss (MBL)) were enrolled in a peri-implant maintenance program and were additionally assessed at 6, 9 and 12 months post-treatment. The study was approved by the Medical Ethical Committee of the University Medical Center Groningen (METc, UMCG with study number 2016/355) and registered in the Dutch national trial register (www.trialregister. nl) under number NL8339. The CONSORT guidelines for reporting a randomized controlled trial were followed (Schulz, Altman, Moher, 2010). Participants Eligibility criteria Between September 2016 and August 2018, 100 patients were screened by one and the same researcher (D.H.) for eligibility. The last follow-up visit took place in November 2019. Eligible participants had at least one dental implant with clinical and radiographical signs of peri-implantitis, which was defined as: probing pocket depth (PPD ≥ 5mm with concomitant bleeding and/or suppuration on probing (BoP/SoP) and progressive loss of marginal bone (MBL) ≥ 2mm, when compared to the baseline radiograph (after placement of the definitive restoration) ((de Waal et al., 2013). All the patients’ eligible implants were included for clinical, radiographical and microbiological assessment. A patient was excluded when one of the following criteria was met: a history of local head and neck radiotherapy, pregnancy and/or lactation, uncontrolled diabetes mellitus (HbA1c > 7% or > 53 mmol/mol), chronic bronchitis and/or asthma, use of antibiotics within 2 months before the baseline assessment, known allergy to chlorhexidine, long- term use of anti-inflammatory drugs, incapability of performing basal oral hygiene measures, implants with bone loss exceeding 2/3 of the length of the implant, implant mobility, implants with no identifiable position for taking proper probing measurements. In addition, when the patient was subjected to a previous reconstructive or resective surgical treatment or previous non-surgical treatment of the peri-implantitis within the last 3 months, a patient was not included. Before participation, oral and written information about the study was provided. All the patients signed a written informed consent prior to enrolment. 3