Background: The discovery of RANKL-RANK-OPG has favored advancing in the study of signaling for skeletal homeostasis. The function of this molecular system has not been proven yet in relation to the orthodontic dental movement. Purpose: To determine the levels of receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) in the tension area of teeth subjected to orthodontic forces. Methods: A sample of 37 premolars (21, experimental group; 16, control group) was analyzed. The experimental group was divided into two groups that received two different forces (4 oz, 7 oz), in two time periods (24 hours and 7 days). The control group was submitted to no force. Periodontal ligament was obtained from the tension area and the RANKL and OPG levels were measured through ELISA (R&D System). The statistical analysis was performed using ANOVA and the Kruskal-Wallis test. Results: RANKL levels of the experimental group were statistically significant after 24 hours of stimulation with orthodontic forces. The average values of OPG were similar in both groups. Conclusions: The expression of RANKL and OPG in the tension area takes place in different ways depending on the magnitude and duration of the force applied during the orthodontic dental movement.KEYWORDSRANKL; RANK; OPG; orthodontic dental movement; tension area; orthodontic force