Abstract: Objective: To establish a peri-microscrew implantitis model in the femur of rats, and investigate the change of proportion of Foxp3⁺ regulatory T cells in peripheral blood. Methods: Twelve male SD rats were divided into normal group, peri-implantitis group, and blank group (n=4). The normal group and peri-implantitis group accepted an implantation of microscrew implant in the distal end of the femur, while the later one underwent cervical ligation immediately around the implants whose upper part was exposed in vitro. The normal group had no events after the implantation, and the blank group only accepted a “fake” operation without implantation. Four weeks after the operation, the abdominal blood was collected and the femur of each group was taken an X-ray examination and detected the the ratio of Foxp3⁺ regulatory T cells (CD4⁺CD25⁺Foxp3⁺) in T lymphocytes (CD4⁺) using flow cytometry. Results: The peri-implantitis group showed an inflammatory granulation tissue around the implants, whose X-ray film indicated an angular absorption of cortical bone and had a lower proportion (0.66±0.32)% of Foxp3⁺ regulatory T cells in the peripheral blood, significantly lower than normal group (2.69±1.19)% and blank group (4.06±1.34)% (P<0.05). There was no statistically significant difference between normal group and the control group. Conclusion: The model of peri-microscrew implantitis in rats’ distal end of femur can be established. Rats with peri-microscrew implantitis have a decrease in the number of Foxp3⁺ regul-atory T cells in peripheral blood, which may be associated with the pathogenisis of peri-microscrew implantitis.

Key words: Microscrew implant, Peri-implantitis, Regulatory T-lymphocytes, Foxp3, Rat