Biochemical markers of bone metabolism in gingival crevicular fluid during early orthodontic tooth movement

Objective: To evaluate the expression of an activator of nuclear factor-kappa (RANK), osteoprotegerin (OPG), osteopontin (OPN), and transforming growth factor beta 1 (TGF-beta 1) in gingival crevicular fluid (GCF) of teeth subjected to orthodontic forces. Materials and Methods: A randomized, pilot clinical trial including 10 healthy volunteers was conducted using a split-mouth design. Orthodontic elastic separators were placed between the second premolar and first molar, with the contralateral quadrant serving as a control. The GCF samples were collected from the tension and compression sites at baseline, 24 hours, and 7 days after the placement of separators. The GCF sample volumes were measured using a Periotron 8000, and total protein concentrations were determined. Levels of RANK, OPG, OPN, and TGF-beta 1 were also analyzed using a multiplex enzyme-linked immunosorbent assay. Results: The control sites remained unchanged throughout the study. In contrast, the concentration of OPG significantly decreased at the compression site by 24 hours, and the amount and concentration of RANK differed significantly between the control, compression, and tension sites after 7 days. A significant increase in absolute TGF-beta 1 levels was also detected at the compression site versus the control and tension sites after 7 days. Conclusion: Bone metabolism is affected by application of force to the teeth by elastic separators. Both increased expression of bone resorptive mediators (eg, RANK and TGF-beta 1) and decreased expression of a bone-forming mediator (eg, OPG) on the compression side were detected. (Angle Orthod. 2013;83:63-69.)