Host Responses in Peri-implant Tissue in Comparison to Periodontal Tissue: A Retrospective Study

Purpose: To investigate inflammatory responses in peri-implant crevicular fluid (PICF) in comparison to periodontal tissue. Materials and Methods: Nineteen participants with healthy implants restored with titanium or gold-casting abutment were included. PICF and gingival crevicular fluid (GCF) were collected for inflammatory cytokine detection by ELISA. Cytokine levels in PICF or GCF of the same individual were compared using the paired t-test, and those from titanium or gold-casting (UCLA) abutment were compared using the independent t-test. Human gingival fibroblast responses to PICF and GCF were then evaluated with one-way ANOVA. Results: The results demonstrated that IL-6, IL-8, TNF alpha, and IFN gamma expressed in PICF are similar to GCF in the same individual. However, IL-1 beta (p = 0.032) and IL-1 alpha (p = 0.030) was statistically significantly higher in PICF than in GCF. IL-8 level was statistically significantly higher with gold-casting than with titanium abutments (p = 0.003). PICF statistically significantly stimulated higher expression of RANKL, IL-1 beta, IL-6, and IL-8 mRNA in human gingival fibroblasts (HGF), while focal adhesion kinase (FAK) suppressed mRNA. Conclusion: The inflammatory cytokines, including IL-1 alpha and IL-1 beta, are higher in healthy peri-implant tissues. Abutment materials may also influence the level of inflammatory cytokines in PICF. Inflammatory mediators in crevicular fluid may affect HGF inflammatory responses and peri-implant tissue integration.