The effect of azathioprine on orthodontic tooth movement

The aim of the present study was to evaluate the effect of Azathioprine (Imuran) on orthodontic tooth movement. The study was conducted on thirty male white Newzeland rabbits. Orthodontic appliance was fixed to each rabbit to apply mesial force on the left maxillary first molar. The rabbits were then divided into two equal groups (Imuran and control groups). In the Imuran group each animal was given a daily dose of 0.5 mg/kg/BW of Azathioprine (Imuran, Glaxo Wellcome, Dartfod, England) in 1 ml solvent (0.01 M NaOH in 0.9%NaCl). Each animal of the control group was given 1 ml of the solvent as a placebo. Both groups were subdivided into three equal subgroups according to the time of evaluation; one day, one week and two weeks. At the predetermined time the maxilla was dissected. The distances of orthodontic tooth mevments were measured. Histological sections parallel to the long axis of the left maxilary first molar were prepared. The sections were stained either by H&E or PAS stains. The changes in the surrounding alveolar bone were monitored. The number and activity of osteoclasts were evaluated. The results revealed that there was no significant defference between the tooth movements occured in the Imuran and control subgroups after one day (P < 0.05). After one and two weeks, the tooth movements were significantly higher in the control subgroups than the Imuran subgroups (P > 0.05). The histological findings showed no difference in the number and activity of osteoclasts in the pressure sides in both control and Imuran subgroups after one day (P < 0.05). On the other hand, the number and actvity of osteoclasts were significantly higher (P > 0.05) in the control subgroups than the study subgroups after one and two weeks. Finally, it could be concluded that; Azathioprine (Imuran) significantly retards the orthodontic tooth movement and decreases the number and activity of osteoclasts.