The Use of Salivary and Gingival Crevicular Fluid Biomarkers in Predicting Orthodontic Treatment Response

Background: Oral fluids are considered a promising diagnostic method to demonstrate the biomarkers for many oral inflammatory and physiological conditions. Orthodontic treatment is associated with changes in bone remodeling and tissue inflammatory biomarkers. Objective: The research assessed the effectiveness of salivary biomarkers, which include cytokines, MMPs, and bone turnover markers, in describing the unwanted oral and dental pathological outcomes and to provide clinical precision in following orthodontic treatment in patients who were treated with the fixed orthodontic appliance. Materials and Methods: Blended longitudinal and Cross-sectional study: one hundred patients were followed up throughout one year after enrollment, aged between twelve and eighteen years old. Salivary and Gingival Crevicular Fluid biomarker concentrations were assayed at the beginning of the study and at multiple time points regarding the treatment. Interleukin IL-1β, Tumor Necrosis Factor TNF-α, Matrix Metalloproteinases MMP8 and MMP9, and bone turnover markers (RANKL/OPG) were the biomarkers included. Results: The mean concentrations of both cytokines were 1.55-fold higher in the first month. MMP-8 and MMP-9 concentrations increased between the third and sixth months from baseline in 50% and 45% respectively. Patients with high cytokine MMP levels resulted in tooth movement, with 15% enhanced compared to the control group, and finished treatment quicker. There were disparities in cytokine levels whereby, generally, males had slightly elevated levels of cytokines compared to the female patients, although this did not influence treatment efficacy. The RANKL/OPG ratio is elevated during the first three months in the active phase of bone remodeling. Conclusion: The reliability of salivary and GCF biomarkers as predictors. Thus, cytokines and MMPs, and the RANKL/OPG ratio, being biomarkers, identify response to a specific treatment and also in orthodontic management, including avoiding root resorption, unwanted bone remodeling, and oral pathologies.