Salivary biomarkers in oral diseases: From caries to cancer-advances, challenges, and future directions.

Human saliva is a complex biological fluid essential for maintaining oral and systemic homeostasis. In recent years, it has emerged as a valuable, non-invasive, and informative diagnostic medium due to its rich composition of proteins, nucleic acids, metabolites, and microorganisms. Salivary biomarkers have been extensively investigated for their potential in early diagnosis, disease monitoring, and prognosis of various oral conditions, such as dental caries, periodontal disease, and oral cancer. Advances in analytical techniques have significantly enhanced the sensitivity and specificity of salivary biomarker detection, deepened our understanding of pathophysiological mechanisms and accelerated their translation into clinical practice. In this chapter, we detail key salivary biomarkers associated with these major oral conditions, emphasizing their potential clinical applications and addressing the challenges inherent in integrating salivary diagnostics into routine dental care. We also explore the biological foundations of saliva production, highlight current methodologies for salivary biomarker analysis, and discuss their clinical significance in oral diseases. Finally, we examine emerging trends and future perspectives for the incorporation of salivary diagnostics into precision oral healthcare.