Histological analysis of the pulp tissue of rats with testosterone deficiency submitted to orthodontic tooth movement induced / Análise histológica do tecido pulpar de ratos com deficiência de testosterona submetidos à movimentação dentária ortodôntica induzida

Abstract

Considering the increased demand for orthodontic treatments in adult and elderly patients, with possible hormonal changes caused by age, this study carried out a histological analysis of pulp alterations in the molars of testosterone-deficient rats submitted to induced tooth movement (ITM), aiming at a better understanding of the pulp’s biological aspects. Thirty-two Wistar rats were used in four experimental groups, with 8 animals in each: G1 –control group animals, without experimental manipulation; G2 – animals submitted to bilateral orchidectomy; G3 – animals submitted to ITM technique; G4 – castrated animals submitted to ITM. We used a nickel-titanium (NiTi) spring to induce tooth movement, exerting a force of 50cN magnitude on the first upper molar. Seven days after the installation of the ITM device, the animals were euthanized, the jaws were dissected and stored in 10% formaldehyde for 24 hours and processed with routine histological techniques. We evaluated the efficiency of the force and verified tooth movement by measuring the distance between the first and second molars, at the cementoenamel junction level. The groups were histologically evaluated in terms of cellularity pattern, presence of dystrophic and hemodynamic alterations in the dental pulp. The ITM device succeeded in inducing tooth movement in the animals of groups G3 and G4, which differed from each other, with a higher movement rate in the group submitted to castration associated with ITM (G4). In the comparative analysis of groups, the animals’ pulp in groups G1 and G2 (not submitted to ITM) presented histological characteristics typical of the pulp tissue. We found no dystrophic changes such as necrosis, fibrosis, nodules, or calcifications in the pulp of experimental animals that could be attributed to ITM. The animals with orthodontic movement, castrated or not, presented dilated and congested vessels, in addition to hyalinized vessels in the root and coronary pulp. However, we observed no histological changes that could be attributed to testosterone deficiency. Thus, in this experimental model, testosterone deficiency did not cause morphological and degenerative changes in the pulp during tooth movement. The vascular alterations observed in the animals resulted from the orthodontic process