Gene Expression in Peri-Implant Bone with Severe Bone Loss: A Pilot Study Using Human Biopsies.

Abstract Peri-implant bone loss is a complication around osseointegrated dental implants. In severe cases, it can lead to implant loosening. The etiology and the process of bone loss are still not fully understood. No published studies have analyzed cytokines in human peri-implant bone biopsies with severe bone loss. This study compares the expression of a selected panel of genetic markers from human bone biopsies and peri-implant crevicular fluid (PICF) surrounding dental implants with severe bone loss, to biopsies from unaffected bone in the same patients. Nine patients planned for implant removal due to severe bone loss were included. PICF samples were collected with paper points from the implant sites. From each patient, one sample of bone adjacent to the implant and one sample of unaffected bone were harvested. The samples were processed and analyzed with qPCR. Expression of proinflammatory markers and markers for bone resorption and tissue degradation was upregulated in bone loss sites compared to unaffected bone. Although the results from PICF were similar, cautious interpretation is needed due to the pilot characteristics of the study. The results indicate that the immune system is active in inflammation and tissue degradation in the bone surrounding implants with severe bone loss. The gene expression findings from implant sites with severe bone loss reflected the clinical situation well, demonstrated by upregulated bone resorption markers and proinflammatory markers compared to unaffected bone. Further research is required to confirm these findings and explore the factors involved in severe bone loss around dental implants.