Abstract

Introduction: Orthodontic treatments are associated with pain. Opioids are commonly used to alleviate such pain which in turn can interfere with orthodontic treatment. Information about the effect of different types of opioids in Orthodontic Tooth Movement (OTM) is not substantial. Aim: To evaluate and compare the effect of three exogenous opioids (Morphine, Codeine and Methadone) on orthodontic tooth movement. Materials and Methods: Forty-eight male Wistar rats were randomly divided into four equal groups. Control group received a normal saline injection, and the three other groups received a daily injection of morphine, methadone, and codeine at the dose of 6,3,30 mg/kg respectively. A NiTi closed coil spring was used to tip the left upper first molar mesially. After twenty-one days of force delivery, the rats were sacrificed, and the rate of tooth movements was measured by a feeler gauge. Then, maxilla was dissected, fixed, and examined histologically. Kruskal-Wallis's test was used for the comparison of OTM between four groups and for multiple comparisons analysis Mann-Whitney test was implemented. Results: The highest amount of tooth movement occurred in the control group (0.279 mm) which was significantly higher than the other three opioid groups (p<0.05). The differences in tooth movement between morphine, methadone, and codeine groups were not statistically significant (p>0.05). There was no statistically significant histological difference between the four groups (p>0.05). Conclusion: All three opioids used in this study reduced OTM regardless of differences in terms of duration of the effect.