Testosterone deficiency and abuse impact the orthodontic tooth movement: an in vivo study

Author(s)

Caio Luiz Bitencourt Reis

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC)
• Defense date: 2024-11-08

Examining board members

Mirian Aiko Nakane Matsumoto; Erika Calvano Kuchler; Daniela Silva Barroso de Oliveira; Maria Bernadete Sasso Stuani

• Advisor: Mirian Aiko Nakane Matsumoto

Abstract

The aim of this study was to evaluate the impact of testosterone deficiency, replacement, and abuse during simulated orthodontic tooth movement (OTM) inananimal model during puberty. Male Wistar rats (n=48) were randomly divided into four experimental groups: ORX, ORX-R, Sham, and Sham-S. At 23 days of age, orchiectomy was performed in the ORX and ORX-R groups, and sham surgery was performed in the Sham and Sham-S groups. Testosterone undecanoate was the exogenous androgenic steroid (EAS) administered in replacement doses to the ORX-R group and in abuse doses to the Sham-S group. The ORX and Sham groups received the medication vehicle as a placebo (castor oil). At 50 days of age, OTM was induced using a closed coil spring installed on the right upper first molar, applying a force of 0.25 Newtons. The animals were euthanized after 10 days of OTM. Plasma levels of adrenocorticotropic hormone (ACTH) and Troponin I were measured using Miliplex kits. The alveolar process surrounding the right upper first molar (moved side) and the left (control side, split-mouth design) was collected for gene expression analysis by real-time PCR. The relative expression of the genes RANK, RANKL, OPG, RUNX2, BMP2, and VEGF was normalized to the ACTB and GAPDH genes. Micro-computed tomography was used to analyze bone quality on the control and moved sides. Histological sections were obtained to analyze inflammatory infiltrate (hematoxylin and eosin staining), apoptosis (TUNEL method), osteoclast differentiation (TRAP method), and immunostaining of eNOS, Runx2, Bmp2, Vegf, Oc,and Otn. Values were compared between groups using ANOVA with Tukey\'s post hoc test, with a 5% alpha error tolerance. ACTH levels were significantly lower in the Sham-S group. There was an increase in the inflammatory infiltrate in the traction region of the moved side in the Sham-S group. All immunomarkers were statistically different between the groups on the control side. Testosterone dysfunction caused increased oxidative stress and endothelial dysfunction in both the control and moved sides, as evaluated by immunostaining of eNOS and Vegf. On the moved side, only the expression of BMP2 and RUNX2 was not statistically different between the ORX-R and Sham-S groups compared to the Sham group. Testosterone deficiency decreased the expression levels of all studied genes on the control side (p<0.05). Bone volume fraction and fractal dimension were statistically different in the Sham-S group compared to the Sham group. In conclusion, testosterone deficiency and abuse impact the healthy outcomes of bone physiology in response to orthodontic movement. (AU)

• FAPESP's process: 21/02704-1 - The impact of testosterone on the orthodontic tooth movement: an in vivo study
• Grantee: Caio Luiz Bitencourt Reis
• Support Opportunities: Scholarships in Brazil - Doctorate