Tehran University of Medical Sciences Journal of Craniomaxillofacial Research 2345-5489 8 3 2022 02 01 122 128 Masood Feizbakhsh Department of Orthodontics, School of Dentistry, Islamic Azad University, Isfahan (Khorasgan) Branch, Isfahan, Iran. Sayed Mohammad Razavi Dental Implant Research Center, Dental Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran; Department of Oral and Maxillofacial Pathology, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran. Valiollah Hajhashemi Department of Pharmacology and Isfahan Pharmaceutical Sciences Research Center, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran. Mahsa Mortazavi Department of Orthodontics, Arthur A.Dugoni School of Dentistry, University of the Pacific, San Francisco, USA. 2021 10 13 2021 10 13 Introduction: Basic fibroblast growth factor (bFGF) is an effective cytokine in angiogenesis and bone remodeling. The aim of this study was to determine the effect of locally injected bFGF on movement rate and root resorption during orthodontic force application in dogs. Materials and Methods: In this experimental animal study, four 10-12 months male dogs were selected and were randomly allocated into two groups. A week following insertion of closing coil spring between the canines and second premolars, 50μg of bFGF was injected to the case group and phosphate saline to the control group once per month. One month after second injection, the distance between the mentioned teeth were measured. Also, root resorption percentage were analyzed on the second premolars. Results: Average maxillary tooth movement rate in case and control groups were found 2.53 and 1.35mm/month respectively. The correspondent mandibular measures were 2.23mm and 1.15mm. These differences were statistically significant (P<0.0001). In respect to root resorption, the differences were found statistically significant (P<0.01) for coronal region in maxilla, which was higher in control group. Regarding the apical and middle regions of both jaws as well as coronal region of mandible the differences were insignificant. Conclusion: The results of the study showed that the local injection of bFGF can increase tooth movement rate and has the potential to decrease root resorption during orthodontic tooth movement in dogs. Keywords: Tooth movement; Root resorption; Fibroblast growth factor. https://jcr.tums.ac.ir/index.php/jcr/article/view/384 https://jcr.tums.ac.ir/index.php/jcr/article/download/384/331