The impact of testosterone on the orthodontic tooth movement: an in vivo study

Abstract

Pubertal growth spurt can modify the patient's response to Orthodontic Tooth Movement (OTM). However, the role of testosterone in OTM was little studied. This study aims to investigate the impact of suppression, replacement, and supraphysiological doses of testosterone during OTM in animal models. 23-day-old Wistar male rats (n=72) will be randomly allocated into four groups. Orchiectomy (ORX) will be performed in two groups, and, in one group, Testosterone Undecanoate (TU) will be administered for replacement. Placebo Surgery (Sham) will be made in two groups, and, in one group, will be administered supraphysiological doses of TU. At 50-day-old, a NiTi closed coil spring will induce the OTM of the first left upper molar in a constant orthodontic force of 0.25 N. The right side of the maxilla will be the control side. The animals will be euthanized after 5 and 10 days of OTM. Images of histological slices will be obtained and stained with HE to inflammation analysis, Red Sirius to collagen analysis and TRAP to osteoclastogenisis analysis. Immunohistochemical and gene expression by RT-qPCR of RANKL, OPG, RUNX2, BMP-2 e VEGF will be performed. The oxidative stress will be assessed by endothelial NOS immunohistochemical, and apoptosis by TUNEL method. Cardiac function will be evaluated by Troponin I serum and adrenal gland by Adrenocorticotropic hormone. Bone quality and volume of root resorption will be evaluated by 3D microtomography. Data will be analyzed at a significance level of 0.05. This study has the potential to generate unpublished results and will be directly applicable in the orthodontic treatment of teenagers because it aims to assess the need to investigate hormonal levels before starting the orthodontic treatment. (AU)