Effects of restraint stress and orthodontic treatment on physical and psychological states in rats.

Objective: To explore the effects of restraint stress and orthodontic tooth movement on the body weight and behavior of rats.

Materials and methods: Twenty 8-week-old male Wistar rats were randomly divided into four groups: sham stress nonorthodontic (CC), sham stress orthodontic (CO), stress nonorthodontic (SC) and stress orthodontic (SO). Rats in the stress group were subjected to restraint stress for 21 days, and those in the orthodontic group received molar retraction on days 8 to 21 (D8-D21). The weights of the rats were measured, and behavioral tests were performed on D0, D10, and D20. Serum corticosterone levels in the rats were measured on D0, D4, D8, D12, D16, and D21.

Results: The weights of rats in the CO, SC, and SO groups were significantly lower than those in the CC group. In the open-field test, the number of times the rats entered the central zone in the CC group was significantly higher than that in the other three groups. In the elevated plus maze test, at D10, the number of times the rats entered the open arms in the SO, SC, and CO groups was significantly lower than that in the CC group. From D12, the serum corticosterone levels in the CO, SC, and SO groups were significantly higher than those in the CC group.

Conclusions: Both restraint stress and orthodontic tooth movement interventions may have adverse effects on weight, behavior, and neuroendocrine responses. However, overlapping the two intervention methods did not increase the magnitude of the effect.