Influence of tamoxifen on periimplant bone remodeling.

The purpose of the present study was to evaluate the bone remodeling of osseointegrated implants installed in tibias of rats modified or not systemically modified by tamoxifen. Seventy-two female rats were used, the animals received bilateral ovariectomy, tibial implant placement bilaterally and after 6 weeks were randomly assigned to two experimental groups (n = 36). Group SS: received saline administration and Group TAM: received administration of tamoxifen citrate via gavage throughout the experimental period. Twelve animals from each group were euthanized at 30, 60 and 90 days after administration of the first dose of the solutions. The right and left tibias were collected, processed with demineralization for histológical, immunohistochemical and percentage analysis of neoformed bone tissue. (PTON) and without demineralization for bone / implant contact analysis (BIC) and for Scanning Electron Microscopy (SEM) and Xray Dispersive Spectroscopy (EDS). The data obtained were submitted to statistical analysis (p <0.05) in a specialized computer program. With regard to implant bone contact, the TAM group presented higher BIC in all experimental periods when compared to the SS group. The TAM group also presented higher PTON in all experimental periods when compared to the SS group. Histológical analysis of periimplant tissues showed that the TAM group presented histológical characteristics that were similar to the control group, however, with a larger amount of peri-implant bone tissue and a smaller amount of connective tissue. In the immunohistochemical staining patterns, when compared to the SS group, the TAM group presented higher immunostaining for RUNX-2 and OCN, lower TRAP labeling and no differences regarding BMP-2/4 labeling. Regarding the EDS analysis, the tamoxifen group presented higher Ca / P fraction in regenerated área in relation to the SS group all experimental periods. Compared to the ss group, the tamoxifen group showed in the SEM analysis a periimplant bone surface with greater presence of collagen fibers from 30 days, being more evident over 90 days, while in the SS group the amount of fibers is maintained. in a lower and decreasing profile. Within the limits of the present study, it can be concluded that Tamoxifen had a positive influence on periimplant bone remodeling in osseointegrated implants. (AU)