Secretory Micro-RNA 29 in Gingival Crevicular Fluid During Canine Retraction

Introduction: Gingival crevicular fluid (GCF) has been widely investigated as a potential source of biomarkers for an individual’s oral and general health information. MicroRNAs (miRNAs) are non-coding RNAs that are involved in post-transcriptional gene regulation. In this study, we investigated potentials of certain miRNAs in GCF as biomarkers for detection of periodontal remodeling during OTM. The aim of the study was to confirm the presence of secretory miRNAs in GCF and investigate temporal expression profiles of specific secretory miRNAs during the course of orthodontic tooth movement. Methods: A total of 70 subjects were recruited in the study from the patients receiving treatment at the University of Illinois at Chicago’s orthodontic clinic. The inclusion criteria included subjects requiring extraction of maxillary first premolars as part of their comprehensive treatment with edgewise fixed appliances. Ultimately 11 GCF samples were collected from healthy subjects between the ages 10 and 18 (mean 14.5 years old), who maintained excellent oral hygiene throughout the study. GCF was collected using absorbent Periopaper strip at six timepoints. T0: prior to bonding the fixed orthodontic appliances T1: on the day of canine retraction T2: 60 minutes after activating the power chain T3: 1 day after the canine retraction visit T4: 7 days after the canine retraction visit T5: between 5 weeks after initiation of canine retraction Human Let7d, g and i were used for normalization of secretory miRNA levels in GCF. Wilcoxon Sign Rank and Kruskal-Wallis and Mann-Whitney U statistical analyses were used in this study Results: In all studied miRNAs, the change in expression of miRNA from T1 to T5 showed statistical significance consistently (p-value ranging from 0.005 to 0.047). Changes between T1 and T2 were only observed in miRNA-29b. Changes between T1 and T4 were observed in both miRNA-101 and miRNA-29b. Analyzing all the time points together, Kruskal-Wallis test showed no statistical significant difference between miRNA-29a, miRNA-29b and miRNA-29c, (p>0.05, p-value ranging from 0.201 to 0.802) indicating the similarity in profile change of miRNA-29 family. Conclusions: We concluded that secretory miRNAs exist in GCF and the expression levels of miRNA-29 family change during orthodontic tooth movement.