OPN gene expression following bone resorption induced by orthodontic tooth movement in rats Dr. Seifi M.,1 Dr. Jessri M. 2 1Associate Professor, Department of Orthodontics, Faculty of Dentistry, Shaheed Beheshti University of Medical Sciences. Tehran, Iran. 2Dentist. (Received 3 Nov, 2007 Accepted 11 August, 2008) Abstract Background & Aim: OPN gene has been shown to play an important role during bone resorption. The significant expression role of OPN gene in bone resorption hypothesizes the increased quantity of this glycoprotein during bone resorption induced by orthodontic tooth movement. The aim of this study was to assess the expression of OPN gene in rat bone resorption induced by orthodontic tooth movement. Materials & Methods: In an experimental study, fixed Ni-Ti closed coil springs were applied for mesial movement of the maxillary left first molars in 13 male 8-week-old Wistar rats. The animals' right maxillary first molars were used as internal controls of the study. The rats were sacrificed 21 days after application of orthodontic appliances. The scratched materials from mesial sides of the alveolar bone were used for PCR evaluation. The collected data were subjected to Wilcoxon Signed Rank Test. Results: Densitometry analysis of OPN coding mRNA on electrophoresis gel exhibited significant increase in gene expression on resorptive (mesial) side of the alveolar bone (P<0.001). The authenticity of PCR assessments was verified by GAPDH gene. Conclusion: Based on the results of this investigation and considering the study limitations, OPN gene expression increases during bone resorption induced by orthodontic tooth movements. Key words: Bone Resorption - OPN - Tooth movement. Corresponding Author: Dr. Seifi M., Associate Professor, Department of Orthodontics, Faculty of Dentistry, Shaheed Beheshti University of Medical Sciences. Tehran, Iran. e.mail: seifimassoud@gmail.com | 
