Elevated levels of 8‐OHdG and PARK7/DJ‐1 in peri‐implantitis mucosa

Background Reactive oxygen species contribute to periodontal tissue homeostasis under control of anti‐oxidative responses. Disruption in this balance induces severe inflammation and extended tissue degradation. Purpose Aim of this study was to identify the expression levels of nuclear factor, erythroid 2 like 2 (NFE2L2/NRF2), Parkinsonism associated deglycase (PARK7/DJ‐1), kelch‐like ECH associated protein 1 (KEAP1), and 8‐hydroxy‐deoxyguanosine (8‐OHdG) in peri‐implant mucosal tissues affected by peri‐implantitis, and to compare the levels to those of periodontally diseased and healthy tissue samples. Methods Tissue biopsies were collected from systemically healthy, non‐smoking 12 peri‐implantitis patients, 13 periodontitis patients, and 13 periodontally healthy controls. Expression levels of NFE2L2/NRF2, PARK7/DJ‐1, KEAP1, and 8‐OHdG in tissue samples were analyzed immunohistochemically. Statistical analysis was performed by one‐way ANOVA with Tukey's HSD test. Results Inflammatory cell infiltration in the connective tissue and loss of architecture in the spinous layer of the epithelium were prominent in peri‐implantitis. Proportions of 8‐OHdG and PARK7/DJ‐1 expressing cells were elevated in both peri‐implantitis (P = .025 for 8‐OHdG and P = .014 for PARK7/DJ‐1) and periodontitis (P = .038 for 8‐OHdG and P = .012 for PARK7/DJ‐1) groups in comparison with controls. Staining intensities of 8‐OHdG and PARK7/DJ‐1 were higher in the periodontitis and peri‐implantitis groups than in the control (P < .01) groups. There was no difference in the expression levels of NFE2L2/NRF2 between the groups. KEAP1 was not observed in any tissue sample. Conclusions Peri‐implantitis is characterized by severe inflammation and architectural changes in the epithelium and connective tissue. The expressions of 8‐OHdG and PARK7/DJ‐1 are elevated in both peri‐implantitis and periodontitis.