The role of salivary proteins in early childhood caries: a scoping review

Early childhood caries (ECC) is one of the most prevalent chronic diseases in children and is influenced by microbial, host, and environmental factors. Saliva plays a significant role in oral defense and contains proteins involved in buffering capacity, immune responses, antimicrobial activity, and enamel remineralization. In recent years, salivary proteins have gained increasing attention as potential non-invasive biomarkers for ECC risk prediction and diagnosis. This scoping review explored the association between salivary proteins and ECC by synthesizing findings from studies published between January 2020 and August 2025. A systematic search of PubMed, EBSCOhost, ScienceDirect, and Google Scholar identified 612 records, of which 10 studies met the inclusion criteria, involving 646 children younger than six years. The review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines, included only English-language publications, and excluded grey literature. A wide range of salivary proteins was examined, including lysozyme, secretory Immunoglobulin A (IgA), histatin-5, cystatin S, α-amylase, matrix metalloproteinases (MMP-8 and MMP-20), statherin, defensins, cathepsin G, mucins, and lactoferrin. The findings indicated that elevated levels of lysozyme, histatin-5, MMP-8, β-defensins, α-defensin-3, cathepsin G, and β-defensin-2 were more consistently associated with caries-active (CA) children, whereas higher concentrations of secretory IgA, cystatin S, α-amylase, statherin, and Mucin-1 (MUC1) were more frequently observed in caries-free (CF) children. However, conflicting results were reported for lysozyme and statherin, likely reflecting methodological heterogeneity across studies. Overall, this review supports the potential role of salivary proteins as biomarkers for ECC, particularly when used in combination as part of a diagnostic panel. Further standardized and multicenter studies are needed to validate these findings and to support the development of saliva-based, child-friendly diagnostic tools for early ECC detection.

Early childhood caries; Saliva; Salivary proteins; Biomarkers; Pediatric dentistry

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