Peri-Implant Mucosal Barrier Dysfunction In Periimplantitis

Abstract

The attachment of gingival epithelium to dental implants has been shown to be an integral part in developing a strong bond between implants and surrounding tissue. While it is known that the absence such a bond may risk peri-implant health, there is a lack of understanding on how the loss of the structural integrity of the epithelial gingiva caused by dysbiosis of the junctional epithelium and disturbance of adhesion molecules can subsequently result in the incidence of peri-implantitis. The aim of this study was to explore the cell population of peri-implant mucosa in peri-implantitis patients using immunohistochemical analysis, exfoliative cytology, and hematoxylin and eosin staining in order to increase our comprehension of the peri-implant mucosal environment and factors related to peri-implant health. Enrolled patients were divided into three groups. The first group (N=12) included subjects undergoing peri-implantitis surgery (diseased), the second group (N=10) included subjects undergoing second stage surgery (absolute health), and the third group (N=5) included subjects undergoing non-implant procedures around erupted teeth (periodontal health). All samples included in this study were collected from disregarded tissue during a single sampling visit. Prior to tissue collection, cytologic samples were collected using a cytobrush for later analysis with a light microscope. After collection, each sample was moved to an empty tube and washed twice with phosphate buffered saline (PBS), each for 5 minutes. 5mL of 70% ethanol was added to the collected samples for storage until they were ready for trimming and processing. Lastly, all tissue samples were embedded in paraffin using a mold and later deparaffinized following the Vector Impact Kit protocol for immunohistochemical and hematoxylin and eosin (H&E) staining. Cytologic smears showed metal-like particles in the peri-implantitis (diseased) group, indicating the presence of titanium in this group. Examination of the other two groups was negative for metal-particles and therefore no titanium presence. For the peri-implantitis group, there was a strong immunohistochemical stain intensity for cytokeratin 19 (CK19) in several regions of the tissue, based on the modified Klein system for reporting the intensity of the staining. It was noted that CK19 for the peri-implantitis group was localized in all cells of the junctional epithelium, while it was mostly localized in the basal layer of the oral epithelium. Immunohistochemical staining for zonula occludens-1 (ZO-1) in the peri-implantitis group was mostly mild, with no specific localization pattern in the junctional epithelium or oral epithelium. There was light immunohistochemical staining, in one region, for E-cadherin (E-cad) in the periimplantitis group. Localization pattern for E-cad in this group was faint staining in the basale layer in both the junctional epithelium and oral epithelium. H&E staining for the peri-implantitis groups showed a pattern of dense inflammatory infiltrate at the junctional and sulcular epithelium. The second group, absolute health, showed strong immunohistochemical staining for ZO-1 in several regions of the oral epithelium. The third group, periodontal health, showed a pattern of mild staining in several regions for CK19 that was mostly localized in the basale layer cells of the junctional epithelium. ZO-1 staining for this group was mostly light and in one region, while staining for E-cad was strong and in several regions. H&E staining for the periodontal health group showed slight changes such as discrete intracellular edema and a mild inflammation without significant changes. On a histological level, descriptive findings from H&E staining for diseased tissue was shown to be consistent with dense inflammatory infiltrate across all layers of the sulcular and junctional epithelium coupled with intracellular edema and vascular infiltrate. Consistent with previous studies, titanium particles were invariably observed in the peri-implant epithelium on a microscopical level via exfoliative cytology. Immunohistochemical analysis revealed that the structural integrity of the epithelium in peri-implantitis was compromised as compared to the peri-implant epithelium around healthy submerged implants as well as the periodontium in periodontal health. Specifically, healthy tissue found in the absolute health and periodontal health groups was associated with the abundance of E-cad, and to a lesser extent, ZO-1. On the other hand, both these key junctional proteins were scarcely present in peri-implantitis junctional epithelia, while the presence of CK19 in large amounts can be linked to the rapid and aberrant turnover of the peri-implant tissue in disease.