IRF4/FGF23 in gingival crevicular fluid: Diagnostic biomarkers for Dentin Hypersensitivity

Background: The aim of this study is to investigate the diagnostic value of interferon regulatory factor 4 (IRF4) and fibroblast growth factor 23 (FGF23) in gingival crevicular fluid (GCF) and serum for dentin hypersensitivity (DH), and to analyze the relationship between IRF4, FGF23 and inflammatory factors and T lymphocyte subsets. Methods: 24 DH patients receiving orthodontic treatment at our institution between 2022 and early 2025 were enrolled as the study cohort, along with 124 healthy controls matched for age and sex. GCF and serum samples were obtained 48 hours post-desensitization therapy to quantify IRF4 and FGF23 levels (via enzyme-linked immunosorbent assay), along with serum inflammatory markers (interleukin [IL]-1β, IL-6, high-sensitivity C-reactive protein [hs-CRP]) and T-cell subpopulations (CD3+, CD4+, CD8+). Statistical analyses included Pearson's correlation to examine relationships between IRF4/FGF23 and clinical parameters, with receiver operating characteristic (ROC) curve analysis determining diagnostic accuracy. Results: The study revealed that GCF and serum levels of IRF4 and FGF23 were significantly upregulated in DH patients compared to healthy controls (P < 0.05), with a strong positive correlation between the two biomarkers (P<0.001). Diagnostic analysis revealed that GCF testing outperformed serum assessment, with the highest accuracy (AUC = 0.846) achieved through combined detection. Notably, IRF4 and FGF23 levels in gingival crevicular fluid were positively correlated with inflammatory markers (IL-1β, IL-6, and hs-CRP). Further immune profiling indicated reduced CD3+ and CD4+ T-cell populations in DH patients versus controls, with IRF4 and FGF23 levels inversely related to these T-cell subsets (P < 0.05).