Cellular expression of DNA damage/repair and reactive oxygen/nitrogen species in human periodontitis and peri-implantitis lesions.

AIM OF THE STUDY To evaluate differences in the cellular expression of DNA damage/repair and reactive oxygen/nitrogen species (RONS) between human periodontitis and peri-implantitis lesions. MATERIAL AND METHODS 40 patients presenting with generalized severe periodontitis and 40 patients with severe peri-implantitis were included. Soft-tissue biopsies were collected from diseased sites in conjunction with surgical therapy and prepared for histological analysis. Four regions of interest (ROIs) were identified; the pocket epithelium (PE), the infiltrated connective tissue (ICT), which was divided in one inner area facing the pocket epithelium (ICT-1) and one outer area (ICT-2). A non-infiltrated connective tissue area (NCT) lateral of the ICT was also selected. RESULTS It was demonstrated that the ICT of peri-implantitis specimens was considerably larger and contained significantly larger area proportions and densities of CD68-, MPO- and iNOS-positive cells than that of periodontitis samples. Cellular densities were overall higher in the inner ICT-zone lateral of the pocket epithelium (ICT-1) than in the outer ICT compartment (ICT-2). While the non-infiltrated connective tissue (NCT) area lateral of the ICT comprised significantly larger proportions and densities of y-H2AX-, iNOS-, NOX2-, MPO- and PAD4/MPO-positive cells in peri-implantitis than in periodontitis sites, a reverse difference was noted for the area proportion and density of 8-OHdG-positive cells in the pocket epithelium (PE). CONCLUSIONS It is suggested that peri-implantitis lesions are associated with an enhanced and upregulated host response and contain larger numbers of neutrophils, macrophages and iNOS-positive cells than periodontitis lesions.