Hypothalamic Obesity Reduces of Orthodontic Tooth Movement and Causes Alterations in the Dental Pulp of Female Rats

Aims: To evaluate whether hypothalamic obesity, when associated with induced tooth movement, can influence the histological structure of the dental pulp in rats. Type of Study: Experimental research. Methodology: Forty female pups of Wistar rats were obtained from the Central Animal Facility of the Western Paraná State University. Twenty pups received daily subcutaneous injections of monosodium glutamate (4 g/kg/day) in the cervical region during the first five days of life to induce obesity (MSG group). The remaining twenty animals received injections of hyperosmotic saline solution (1.25 g/kg/day) and served as the non-obese control group (CTL). The animals were then divided into four experimental groups (n = 10/group): Group 1: Non-obese rats not subjected to induced tooth movement (CTL); Group 2: Non-obese rats subjected to induced tooth movement (CTL + ITM); Group 3: Obese rats not subjected to induced tooth movement (MSG); Group 4: Obese rats subjected to induced tooth movement (MSG + ITM). At 97 days, all animals were weighed and euthanized. Results: Obese animals in the MSG+ITM group exhibited a higher Lee index and increased retroperitoneal and perigonadal fat deposits compared to the CTL+ITM group (P < 0.05). They also showed a lower rate of tooth movement than the non-obese animals in the CTL+ITM group (P<0.05). Furthermore, obese animals subjected to tooth movement (MSG+ITM) demonstrated more frequent occurrences of mild inflammatory infiltrate, increased cellularity, and dystrophic and hemodynamic changes compared to the other groups. Conclusion: Hypothalamic obesity associated with induced tooth movement leads to reduced tooth movement and increased occurrences of inflammatory infiltrate, as well as dystrophic and hemodynamic changes in the dental pulp.