Abstract: Saliva is an underexplored biological fluid in clinical diagnostics compared to blood, urine, serum, and other bodily fluids. Due to its non-invasive collection, rich biomolecular composition, and cost-effectiveness, saliva holds potential as a point-of-care diagnostic tool for the early detection of diseases. This literature review was conducted through a systematic search across three major electronic databases: PubMed/MEDLINE, Scopus, and Web of Science. The search strategy combined MeSH terms and keywords, with primary terms including “Saliva as Diagnostic Tool,” “Biomarker,” and “Systemic Diseases.” The clinical correlation of various salivary biomarkers, such as CRP, 1,5-AG, and adiponectin with type 2 diabetes, as well as myoglobin and matrix metalloproteinases (MMPs) with cardiovascular diseases, is well established. Early detection of salivary biomarkers within the first 24 hours has been observed in patients with acute myocardial infarction (AMI). Similarly, salivary pH, accumulation of Streptococcus mutans (S. mutans), and MMP levels indicate the incidence of dental caries and periodontal problems. Although saliva enables specific and selective biomarker detection, several gaps remain. This review highlights salivary biomarkers that have been widely correlated with their clinical applications and underscores the broad potential of saliva for disease diagnosis and monitoring, ranging from local oral conditions to systemic disorders and cancer. However, using saliva as a diagnostic fluid presents challenges, including ethical, social, and legal concerns, as well as issues regarding scientific validation and clinical applicability. This paper provides a comprehensive overview of these biomarkers and identifies research areas requiring further attention.
Dihingia et al. (2026) studied this question.