Detection and comparison of neutrophil extracellular traps in tissue samples of peri‐implantitis, periodontitis, and healthy patients: A pilot study

Objective The aim of this study was to detect and compare the tissular expression of neutrophil extracellular traps (NETs) in peri‐implant and periodontal samples of patients with peri‐implantitis, periodontitis, and controls. Materials and Methods An observational study was performed on patients with peri‐implantitis, periodontitis, and controls. Peri‐implant and/or periodontal clinical examinations were performed on each participant. Tissue samples were collected during tooth/implant extraction for clinical reasons. Electron microscopy analysis, Picro‐Sirius red staining, immunohistochemical (CD15), and immunofluorescence (citrullinated H3 and myeloperoxidase) techniques were performed to detect NET‐related structures and the degree of connective tissue destruction, between the study groups. Results Sixty‐four patients were included in the study: 28 peri‐implantitis, 26 periodontitis, and 10 controls, with a total of 51 implants, 26 periodontal teeth, and 10 control teeth. Neutrophil release of nuclear content was observed in transmission electron microscopy. Immunohistochemical analysis showed a greater CD15 expression in both peri‐implantitis and periodontitis compared to controls ( p < 0.001), and peri‐implantitis presented lower levels of connective tissue and collagen compared to both periodontitis ( p = 0.044; p < 0.001) and controls ( p < 0.001). Immunofluorescence showed greater citH3 expression in peri‐implantitis than the one found in both periodontitis ( p = 0.003) and controls ( p = 0.048). Conclusions A greater presence and involvement of neutrophils, as well as a greater connective tissue destruction were observed in cases of peri‐implantitis. A higher expression of NET‐related markers was found in mucosal samples of peri‐implantitis compared to periodontitis and controls.