Effectiveness and Safety of Mechanical Debridement for Treating Experimental Peri-Implantitis in Elderly Rats Receiving Oncological Dosages of Zoledronate

This study evaluated the effectiveness and safety of mechanical debridement (MD) in treating experimental peri-implantitis (EPI) in rats with osseointegrated implants, specifically those treated with high-dose zoledronate. Senescent Wistar rats underwent the extraction of their upper incisor, followed by immediate implant placement. After 8 weeks, the implants were exposed, and a transmucosal component was placed. The animals were divided into four groups: Control (C), ZOL, ZOL-EPI, and ZOL-EPI-MD. In the 9th week, drug treatment commenced, consisting of the administration of 0.45 mL of a vehicle (for group C) or zoledronate (for groups ZOL, ZOL-EPI, and ZOL-EPI-MD) every 4 days over 10 weeks. After 5 weeks of drug treatment, a cotton bandage was placed around the implants to induce EPI in the ZOL-EPI and ZOL-EPI-MD groups. In the ZOL-EPI-MD group, the ligature was removed at week 16, and local treatment was performed using MD. Euthanasia was conducted at week 19. Histological sections were obtained and stained with hematoxylin-eosin for histopathological and histometric analyses, such as the percentage of total bone tissue (B.Ar/T.Ar) and the percentage of non-vital bone tissue (NVB.Ar/B.Ar). Immunohistochemical reactions were performed to detect TNFα, IL-1β, VEGF, OCN, and TRAP. In the peri-implant connective tissue, mild, intense, and moderate inflammatory infiltrates were observed in the ZOL, ZOL-EPI, and ZOL-EPI-MD groups, respectively. Immunolabeling for TNFα and IL-1β correlated with these histopathological findings. The ZOL and ZOL-EPI-MD groups showed lower immunolabeling for VEGF compared to the control group. There was a reduction in TRAP-positive cells and lower immunolabeling for OCN in the groups treated with zoledronate, with the ZOL-EPI-MD group displaying even lower levels of OCN compared to the ZOL group. While there was no significant difference in B.Ar/T.Ar across the groups, both the ZOL, ZOL-EPI, and ZOL-EPI-MD groups exhibited higher levels of NVB.Ar/B.Ar, with the ZOL-EPI-MD group showing the highest NVB.Ar/B.Ar compared to ZOL and the other groups. In conclusion, MD, as a standalone treatment, showed neither effectiveness nor safety in the management of EPI in rats that received high doses of zoledronate.