Diederik Hentenaar

85 Erythritol air-polishing in surgical peri-implantitis treatment peri-implant bone defect was measured at four sites around the implant (mesial, distal, buccal, palatinal) taking the implant-abutment platform as reference and classified according to the bone defect morphology classification by Schwarz et al. 2007. Radiographical assessment Radiographs were taken at baseline and 3, 6 and 12 months after treatment (Planmeca Intra X-ray unit; Planmeca, Helsinki, Finland). To standardize the peri-apical radiographs and to assure perpendicularity ( i.e., positioning of the film parallel to the long axis of the implant) an individualized X-ray holder and paralleling technique were used. Panoramic images were taken if peri-apical radiographs were painful for the patient ( e.g., painful to the floor of the mouth), or if no position was possible in which reproducible images could be made. Peri-implant bone loss was measured using the DICOM software (DicomWorks 1.5). Calibration of each radiograph took place on a 3-point reference scale using the known implant length and/or diameter. Bone level differences were calculated for the mesial and distal site of the implant. The outer points of the implant connection plateau were taken as reference to which the initial bone level was present (in bone level implants). In the presence of a smooth transgingival segment of the implant (1-stage implant systems i.e., tissue level implants) measurement corrections were made. In order to calculate the inter-observer and intra-observer agreement, radiographic images of ten randomly selected implants were examined twice by the same researcher (D.H.) and once by another researcher (H.M.), both of whom were blinded regarding group allocation. High intraclass correlation (0.98) was found after which D.H. measured all the X-ray images. Microbiological assessment Microbiological samples from the peri-implant sulcus were obtained before and 12 months after surgical therapy using 4 sterile paper points. Supragingival plaque was mechanically removed before sampling. Samples were taken from four sites around the implant (mesiobuccal, distobuccal, mesioligual, distolingual). If a patient had more than one implant, sampling was divided over the implants, taking the deepest pocket per implant. The samples collected from each patient were pooled in an empty vial. In dentate patients, bacterial samples were also taken from the periodontal sites with the deepest probing pocket depth in each quadrant. If no deepened pockets were present, samples were taken from the mesiobuccal pockets of the first molars. Outcome variables were the presence and numbers of the following periodontal marker species; Aggregatibacter actinomycetemcomitans ( Aa ), Porphyromonas gingivalis (Pg ), Prevotella intermedia (Pi) , Tannerella forsythia (Tf ) , Fusobacterium nucleatum (Fn) , Parvimonas micra (Pm) , Treponema denticola (Td) , and Filifactor alocis (Fa) . Microbial samples were sent 4