Assessment of tumor necrosis factor alpha (TNFα) and interleukin 6 level in gingival crevicular fluid during orthodontic tooth movement: a randomized split-mouth clinical trial

BACKGROUND: Orthodontic tooth movement (OTM) is based on induction of periodontal tissue remodeling. Mechanical tooth stimulation results in the release of pro-inflammatory mediators. These mediators cause bone resorption and deposition at the pressure and tension sites and play a role in OTM. Thus, assessment of chemical biomarkers can help determine the exact amount of load and its duration of application required for each tooth and select the most efficient treatment plan with minimal complications. OBJECTIVE: This study aimed to determine the level of tumor necrosis factor alpha (TNFα) and interleukin 6 (IL-6) in gingival crevicular fluid (GCF) during OTM. METHODS: This randomized split-mouth clinical trial (parallel) was performed on 10 patients who were presenting to the Orthodontic Department of Qazvin University of Medical Sciences from November 2015 to June 2016. A canine tooth was randomly selected as the study group and subjected to distalization force while the contralateral canine tooth served as control. Using paper strip, GCF was collected from the study and control teeth prior to orthodontic force application (T0), one hour after (T1) and 28 days after force application (T2), then the level of TNFα and IL-6 was measured using ELISA. Data were analyzed using SPSS version 20 via Friedman and Wilcoxon test, and considering the significance level at p<0.05. RESULTS: The level of TNFα (p=0.0799) and IL-6 (p=0.678) at both sides of study teeth was higher than both side of control teeth at T1. Also, the level of IL-6 (p=0.515) and TNFα (p=0.508) were higher at the tension side compared to the pressure side; but the difference was not statistically significant. CONCLUSION: Due to the free circulation of GCF in gingival sulcus, the level of mediators in the GCF collected from the mesial and distal areas alone cannot serve as a suitable index for assessment of activity at the tension and pressure sites. TRIAL REGISTRATION: The trial was registered at the Iranian Registry of Clinical Trials with the IRCT ID: IRCT2017030632903N2. FUNDING: The present study was supported by a grant from the Research Council, Qazvin University of Medical Sciences, Qazvin, Iran (thesis no.: 40).