Salivary Thy-1 (CD90) as a diagnostic and prognostic biomarker in periodontal disease: current insights and future directions

Abstract Background Periodontal disease affects over 50% of the global adult population, representing a significant public health burden. Current diagnostic methods rely primarily on clinical parameters that may not reflect underlying molecular pathophysiology. Salivary biomarkers offer noninvasive disease detection, with emerging evidence suggesting Thy-1 (CD90) may serve as a novel diagnostic indicator. Objective This review synthesizes current evidence regarding salivary Thy-1 as a biomarker in periodontal disease, examining its biological functions, diagnostic potential, and relevance to inflammatory processes. Patients and methods Literature search across PubMed, Scopus, and Web of Science (2019–2025) using terms including “Thy-1,” “CD90,” “periodontal disease,” and “salivary biomarkers”. Results Salivary Thy-1 levels are significantly elevated in periodontitis patients compared to healthy controls, correlating positively with clinical parameters. Thy-1 plays crucial roles in mesenchymal stem cell differentiation and tissue regeneration, with Thy-1-negative inflammatory fibroblasts mediating tissue fibrosis. Conclusions Salivary Thy-1 emerges as a promising biomarker for periodontal disease diagnosis and monitoring. However, standardization, validation in diverse populations, and integration with other biomarkers are needed before clinical implementation.