The Changes of Th17 Cytokines Expression and Its Correlation with Receptor Activator of Nuclear Factor Kappa B Ligand During Orthodontic Tooth Movement

Background: IL-17 is reported to be associated with the pathophysiology of Orthodontic Tooth Movement (OTM) by affecting osteoclastogenesis. Objective: To explore the changes of Th17 cytokines (IL-17, IL-23 and IL-27) expression and its correlation with receptor activator of nuclear factor kappa B ligand during orthodontic tooth movement. Methods: Thirty patients who needed extraction of the first premolar during orthodontic treatment were included. The gingival crevicular fluid was sampled at the day of application (T0), one hour (T1), 24 hours (T2), one week (T3), 4 weeks (T4) and 12 weeks (T5) after the application of orthodontic force. The expression of Th17 cytokines and receptor activator of nuclear factor kappa B ligand (RANKL) as well as their correlations were measured by using enzyme-linked immunosorbent assay. Results: The levels of IL- 17A, IL-17F, IL-23 and IL-27 at both tension and pressure side of study teeth at T2-T4 were significantly higher comparing with that of T0 and T1. Moreover, the expression of IL-27 at both tension and pressure sides of study teeth at T2-T4 were significantly lower comparing with that of T0 and T1. At T5, IL-17A, IL-17F, IL-23 and IL-27 returned to baseline level. For the control group, the cytokines were not significantly different at various time points. The expression of IL-17A, IL-17F and IL-23 were positively correlated with RANKL expression at T2-T4, whereas the IL-27 was negatively correlated with RANKL expression at T2-T4. Conclusion: This study proved preliminary evidence that Th17 inflammation may be involved in the regulation of OTM.