Alveolar bone repair post tooth extraction of 129/SV- WT and 129/Sv 5LOKO elderly female mice treated with high-potency bisphosphonate

Abstract

The chronicle use of nitrogen containing bisphosphonates (nBP) for the treatment of bone metabolism diseases and disorders, such osteoporosis, is a therapeutic treatment well established, mainly involving patients at age over to 60 years old. However, this treatment is also related to the development of Osteonecrosis of Jaw (ONJ), and the risk of ONJ occurrence increase after surgical and invasive treatments, such as dental extractions. Despite ONJ has been well recognized, the cellular and inflammatory mechanisms involving its pathogenesis remain poorly understood, mainly considering the role of nPBs on the immunological system components. Then, this study aims to analyze the influence of zoledronic acid administration on the bone repair post tooth extraction in 129-SV WT mice in comparison to mice with genetic disruption for the enzyme 5-lypoxigenase (129-SV 5LOKO), which has a osteopetrotic phenotype. Thus, 20 female mice 129/Sv WT and 20 mice 5LOKO, at the age of 64 weeks, will be submitted to the right upper incisor extraction and euthansied after 7 and 21 days post surgery to samples collection. Animal will be divided into two groups: Control (treated with saline solution, at 0,9%) and ZL (intraperitoneal injection [II] of 0,1mL of Zoledronic Acid [ZA] at the dosage of 250ug/Kg) starting the treatment at 4 weeks before the surgeries and continuing until the end of experimental periods (7 and 21 days). After the euthanasia, 5 specimens of each group and experimental period will be fixed in 10% formalin formalina and submitted to the microCT scanning, then submitted to histological processing for performing histolofical sections. The microCT scannings will be processed and analyzed for qualitative (tridimensional) and quantitative evaluations from bone inside of alveolar sockets after tooth extraction. The histological slices will be stainged with hematoxilin and eosin (H&E), as well anlyzed for immunolabeling of macrophages (F480+ cells), osteoblasts (Runx2+ cells) and osteoclasts (TRAP+ cells). After quantitative data acquisition, suitable statistical tests will be applied with significance level of 5%.