Characterization of microRNA-101, -124, -143, -145, -223 in GCF during Orthodontic Tratment

MicroRNAs (miRNAs or miRs) are small noncoding, single stranded RNA molecules discovered in the early 1990s. miRNAs have been studied and proven to be related to many diseases, including cancers, autoimmune disorders, and bone metabolism disorders. miRNA has been found both intracellularly and extracellularly in body fluids including gingival crevicular fluid (GCF). GCF is reported to be a well-known source of biomarkers related to different conditions of oral and periodontal tissues including periodontal diseases and inflammation. The purpose of this study was to investigate the presence and expression profiles of specific miRNAs in GCF. In addition, the correlation between the expression of these miRNAs and the rate of tooth movement during orthodontic treatment was investigated. In this study, we focused on the expression of the specific miRNAs, including miRNA-101, -124, -143, -145, and -223 due to their roles in osteoblast/clast differentiation and functions, angiogenesis and inflammation. In this study, twelve healthy subjects with excellent oral hygiene who required orthodontic treatment with upper first premolar extractions were recruited and their GCF samples were collected during a 7-week canine retraction period. Gingival crevicular fluid collection with Periopapers and intraoral scanning were performed at 5 time points during the canine retraction as follows: T0: prior to bonding fixed orthodontic appliances T1: on the day of initial canine retraction, before temporary anchorage device placement T2: 2 weeks after initiation of canine retraction T3: 5 weeks after initiation of canine retraction T4: 7 weeks after initiation of retraction Three-dimensional digital models from the intraoral scanning were created and superimposed for evaluation of tooth movement. The expression of each studied miRNAs was evaluated using reverse transcription realtime polymerase chain reaction (RT-realtime PCR). The expression profile of each miRNA was evaluated using the non-parametric tests Friedman Repeated Measures and Wilcoxon Signed Rank dependent samples. Spearman Rho statistical analysis was used to evaluate the correlation between the expression profile of the studied miRNAs and the distance of tooth movement. The significance level was set at 0.05. The result showed that the tooth moved at a rate of 0.2mm/week during 7-week of canine retraction. A significant expression profile change in microRNA-143, -145 and -223 was detected during the 7-week canine retraction period and a moderate correlation was found between expression levels of microRNA-143, 145, and -223 and the rate of tooth movement (p<0.05) at the 5-week time point. The expression of microRNA-143, -145 and -223 significantly changed during tooth movement and was negatively correlated with the distance of tooth movement during the 7-week canine retraction. No significant difference was found in microRNA-124 expression level but microRNA-124 expression levels showed significant positive correlation with the distance of tooth movement at week 5.