Aim: The aim of the present study was to evaluate the salivary level of sRANKL and OPG and sRANKL/OPG ratio during the clinical orthodontic tooth movement. Materials and Methods: 20 female patients with age range of 14-20 years with mild crowding and class I malocclusion participated in this study. Unstimulated saliva collected to evaluate the level of sRANKL and OPG prior to orthodontic treatment, 24 hours, 2, 5, and 8 weeks after device activation. ELISA test was performed to measure the concentration of biomarkers and data were analyzed by SPSS version 11.5 software with significance level set at <0.05. Results: Concentration of sRANKL and OPG and also sRANKL/OPG ratio was significantly different between time points. Salivary level of sRANKL decreased after 24 hours and then increased. OPG was decreased after 24 hours and then increased in next follow up measurements except in the 5th week in which it was decreased. SRANKL/OPG ratio increased after 24 hours, decreased after 2 weeks, and then increased after 5 and 8 weeks. Salivary level of both markers and their ratio was significantly higher in the 8th week measurement in comparison to other time points (P-value < 0.05). Conclusion: Based on the results of the present study, evaluation of sRANKL, OPG, and sRANKL/OPG ratio in patients under orthodontic treatment could lead to identification of tooth movement phases after applying orthodontic forces. Clinical Significance: Our study proposed the sRANKL and OPG salivary levels as the molecular markers of different phases of orthodontic tooth movement. These markers could be use for assessment of bone remodeling during orthodontic movement and the response of individuals to treatment.
