Purpose <p>To analyze and compare the differences in orthodontic pain-related behavior between adolescent and adult rats.</p> Methods <p>Twenty 6‑week-old male Sprague–Dawley rats were used to represent adolescent animals, and twenty 8‑month-old male Sprague–Dawley rats were used as adult animals. Ten animals of each group were randomly selected as the control group, and ten as the experimental group. In the experimental groups, each rat was subjected to an orthodontic force. Body weight, food intake weight, and face-grooming activity were recorded, and the open-field and light/dark box tests were conducted on days&#xa0;1, 3, 7, and 10&#xa0;after force loading.</p> Results <p>In adolescent rats, body weight and food intake weight of the experimental group were lower than those of the control group at some time points. The frequency and duration of face grooming in the adolescent rats in the experimental group were greater than those in the control group. On day&#xa0;1, the distance and frequency that the rats travelled in the center in the open-field test and the frequency that they entered the light box in the light/dark box test in the experimental group were less than in the control group. There was no obvious difference in the indices above between the control and experimental groups of the adult rats.</p> Conclusion <p>Adolescent and adult rats demonstrated different patterns of orthodontic pain-related behaviors. Compared with adult rats, adolescent rats exhibited more intense and earlier responses to orthodontic pain.</p>