Effects of Force Constancy on the Distribution of Interleukin-1 Beta and Tumor Necrosis Factor-Alpha Levels

Objective:The purpose of this study was to evaluate levels of interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) in gingival crevicular fluid (GCF) with hybrid and PG retractors, which have differences in constancy of force.Materials and Method:Forty canine teeth of 10 orthodontic patients were distalized with hybrid or PG retractors. The GCF was sampled from the distal sides of the canines at baseline, hour 1, day 1, month 1, and month 2. In the PG group, samples were re-collected 1 hour and 1 day after reactivation at month 1. Two-way ANOVA, paired t test, and Friedman and Wilcoxon tests were used for statistical analysis.Results:The IL-1β level increased at hour 1 and month 2 in the upper and lower hybrid groups, whereas upper PG group increased at hour 1, month 1 + 1 hour, and month 2. The TNF-α level increased at hour 1 and declined afterward in the upper hybrid group. The only difference between the 2 retractors was found in TNF-α levels, which were higher at day 1 and month 2 in the upper PG group.Conclusion:Continuous but diminishing forces produced by PG mechanics enhanced levels of TNF-α significantly at day 1 and month 2 compared with the constant and continuous forces applied by the hybrid retractor in the upper arch. Despite this difference, both retractors induced similar effects in IL-1β and TNF-α production and in the amount of tooth movement.