Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 4 2013 07 15 303 11 Ahmad Sodagar Associate Professor, Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Tahura Etezadi Resident of Orthodontics, Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Pouria Motahhary Associate Professor, Department of Oral Pathology, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Ahmad Reza Dehpour Professor Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Hamed Vaziri Orthodontist, Private Practice, Farmington CT, USA. Arash Khojasteh Assistant Professor, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Director of Basic Science research, Dental Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2015 10 16 Inhibition of prostaglandin (PGs) production leads to decrease in orthodontic tooth movement (OTM). It is not known whether inhibition of cyclooxygenase-1 (COX-1) or cyclooxygenase-2 (COX-2) is the key mechanism for this effect. In this study, the effect of celecoxib, a highly-selective COX-2 inhibitor, was investigated on OTM in rats.Four groups of male rats (seven animals in each goup) were used in the study. A 5mm-long nickel-titanium closed-coil spring was ligated between the right maxillary incisor and the first molar of each rat to deliver an initial force of 60g. All four groups recieved orthodontic appliances, group 1 received no injections, group 2 received celecoxib injections (0.3 mg in 0.1 ml saline solution), group 3 recieved normal saline injections (0.1 ml saline solution), and group 4 recieved needle penetration without injecting any solution. The local injections were carried out every 3 days for 18 days. All injections were subperiosteal and given in the upper right first molar mucosa. The animals were sacrificed 21 days after appliance insertion and OTM was measured.In the animals treated with celecoxib a statistically significant decrease in OTM was observed compared with the other groups. Histological findings revealed that osteoclast count was significantly lower in group 2 compared with the other groups (P https://fid.tums.ac.ir/index.php/fid/article/view/642 https://fid.tums.ac.ir/index.php/fid/article/download/642/617