Effects of metformin on bone tissue around titanium implant inserted in tibiae of rats: histometric and immunohistochemistry evaluations

Abstract

Besides its well-recognized role as a hypoglycemiant agent in the treatment of type 2 diabetes, the metformin has been also suggested as a drug able to stimulate the activity of osteoblasts. Therefore, the aim of this study will be to evaluate, by means of histometric and immunohistochemistry analyses, the influence of metformin administration on bone to implant contact, on bone area within the limits of the implant threads and, on the number of positive cells for osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL), around titanium implants placed in the tibiae of rats. Thirty Wistar rats will be allocated into one of the following experimental groups: Control - water administration during all experimental period; Metformin - administration of metformin (100mg/kg of weight per day) during all experimental period. One screw-type rough surface titanium implant presenting of 4.0 mm in length and 2.2 mm in diameter will be inserted in one of the tibiae of the rats. After 30 days, the animals will be euthanatized. The tibiae will be removed and processed to obtain undecalcified (10 specimens) and decalcified (5 specimens) specimens. The undecalcified histological sections will be used for the histometric analyses. The decalcified histological sections will be used for immunohistochemistry analyses. Using specific software, the following measurements will be performed: bone-to-implant contact, bone area within the implant threads and the number of positive cells for RANKL and OPG around implants. Histometric and immunohistochemistry data will be analyzed separately for medullar and cortical bone. For the statistical analysis, the normality of the data will be firstly verified. Afterwards, according to the normality of the data, histometric and immunohistochemistry findings will be compared by the unpaired or Mann-Whitney test. The level of significance will be set at 5%.