Effects of Hypothyroidism Associated with Dental Trauma on Induced Tooth Movement of Female Rat Molars
Ana Carolina Rodrigues da Rosa
Biologics Science and Health Center, State University of Western Parana (UNIOESTE), Rua Universitária, 2069 – Bairro Universitário, Cascavel, Paraná, Postal code: 85819-110, Brazil.
Hellen Cristina Budel Brandão
Biologics Science and Health Center, State University of Western Parana (UNIOESTE), Rua Universitária, 2069 – Bairro Universitário, Cascavel, Paraná, Postal code: 85819-110, Brazil.
Marlon Rosin
Biologics Science and Health Center, State University of Western Parana (UNIOESTE), Rua Universitária, 2069 – Bairro Universitário, Cascavel, Paraná, Postal code: 85819-110, Brazil.
Elaine Manoela Porto
Biologics Science and Health Center, State University of Western Parana (UNIOESTE), Rua Universitária, 2069 – Bairro Universitário, Cascavel, Paraná, Postal code: 85819-110, Brazil.
João Paulo de Arruda Amorim *
Biologics Science and Health Center, State University of Western Parana (UNIOESTE), Rua Universitária, 2069 – Bairro Universitário, Cascavel, Paraná, Postal code: 85819-110, Brazil.
*Author to whom correspondence should be addressed.
Abstract
Aims: The aim of this study was to evaluate the influence of hypothyroidism associated with dentoalveolar trauma on the induced tooth movement of female rats molars.
Study Design: Experimental research.
Methodology: Forty-eight female Wistar rats were randomly divided into eight experimental groups (n=6 per group): Group 1 – control: animals that were not subjected to any experimental procedure; Group 2: animals that were subjected only to hypothyroidism (HPT); Group 3: animals that were subjected only to dentoalveolar trauma (DT); Group 4: animals that were subjected to HPT+ DT; Group 5: animals that underwent induced tooth movement (ITM); Group 6: animals that underwent DT+ITM; Group 7: animals that underwent HPT+ITM; and Group 8: animals that underwent HPT+DT+ITM. At the end of the experimental period, the animals were weighed and euthanized. The right hemimaxillae were removed, fixed in 10% formalin, decalcified, embedded in Paraplast, cut to 5 µm thickness, and stained with hematoxylin and eosin. the histological slides, and histomorphometric analysis of external root resorption were performed.
Results: The animals that consumed propylthiouracil (0.05% diluted in water) showed lower concentrations of T3 and T4 but higher thyroid-stimulating hormone. The tooth movement rate was significantly higher in the animals of the HPT+DT+ITM group than the other groups (p<0.05). The HPT+ITM group showed greater tooth movement than the ITM and DT+ITM groups (p<0.05). Among the animals in the groups without the tooth movement device, the HPT group had the smallest areas of root resorption when compared to the CTL, DT, and HPT+DT groups (p<0.05). In the analysis of the groups with tooth movement devices, the HPT+ITM group had a smaller root resorption area than the other groups with tooth movement devices (p<0.05). Animals in the HPT+DT+ITM group exhibited the highest root resorption area out of all experimental groups (p<0.001). The animals in the DT, HPT+DT, ITM, HPT+ITM, and DT+ITM groups showed occasional periodontal ligament disorganization, and the animals in the HPT+DT+ITM group had moderate disorganization. In the evaluation of hyaline areas, the groups that underwent DT and/or ITM (DT, HPT+DT, ITM, DT+ITM, HPT+ITM, and HPT+DT+ITM) showed a moderate presence of hyaline areas. Regarding vascular changes in the periodontal ligament, the presence of giant cells, hyperemia, and inflammatory infiltrate were observed in the ITM, DT+ITM, HPT+ITM, and HPT+DT+ITM groups.
Conclusion: We conclude that hypothyroidism associated with dental trauma causes increase in the rate of tooth movement and greater occurrence external root resorption during orthodontic movement in female rats molars.
Keywords: Orthodontic movement, hypothyroidism, dental trauma, rats