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

IL-17 is reported to be associated with the pathophysiology of Orthodontic Tooth Movement (OTM) by affecting osteoclastogenesis.  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 (RANKL) during orthodontic tooth movement.  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), four weeks (T4), and 12 weeks (T5) after the application of orthodontic force. The expression of Th17 cytokines and RANKL were measured by using enzyme-linked immunosorbent assay and, their correlations were assessed. The levels of IL-17A, IL-17F, IL-23, and IL-27 at both tension and pressure sides of studied teeth at T2-T4 were significantly higher compared with that of T0 and T1. Moreover, the expression of IL-27 at both tension and pressure sides of studied teeth at T2-T4 was significantly lower compared with that of T0 and T1. At T5, IL-17A, IL-17F, IL-23, and IL-27 returned to the baseline level. For the control group, the cytokines were notsignificantly different at various time points. The expression of IL-17A, IL-17F, and IL-23 was positively correlated with RANKL expression at T2-T4, whereas the IL-27 was negatively correlated with RANKL expression at T2-T4. This study provided preliminary evidence that Th17 cytokines may be involved in the regulation of OTM.