Evaluation of Gingival Tissue Pathological Changes in Human Peri-implantitis: Histological, Immunohistochemical and Ultrastructural Study

Aims: The current research was performed to study histopathological, immunohistochemical and ultrastructural characteristics of gingival tissue in peri-implantitis. Methods & Results: This study examined 25 patients between ages of 30–40 years. Twenty patients were selected with peri-implantitis (peri-implantitis group) in which inflamed gingival tissues were surgically removed. The gingival soft tissue collars from five healthy patients with partially impacted third molar were surgically removed (control group). All gingival tissue samples were examined histologically and ultrastructurally. Immunoreactivity to CD3 and CD20 antibodies was also evaluated. Cases of peri-implantitis stained with hematoxylin and eosin demonstrated hyperplastic nonkeratinized epithelium with downward growth of rete ridges. Connective tissue stroma revealed prominent vascularity, proliferation of fibrous tissue and focally aggregated inflammatory cell infiltration localized to the subepithelial area. Immunohistochemical results exhibited large numbers of T (CD3+) and B (CD20+) lymphocytes in peri-implantitis compared to normal tissue with a statistically significant difference. All cases of peri-implantitis demonstrated no significant difference between T and B lymphocytes. Transmission electron microscope showed wide intercellular spaces with fine bundles of keratin intermediate filaments around the nucleus. Fibrous connective tissue stroma with active fibroblasts and numerous mixed inflammatory cells (plasma cells, mast cells and numerous activated lymphocytes) were also revealed. Conclusions: Variable histopathological changes appeared in peri-implantitis soft tissue including hyperplastic nonkeratinized epithelium, mixed inflammatory cell infiltration with no statistical difference between T and B lymphocytes, excessive collagenization and vascular proliferation. Understanding these histopathological alterations may help clinicians in better management of peri- implantitis condition to ensure longevity of dental implants.