Abstract
The paradigm of dental medicine is shifting from a reactive surgical model to precision pediatric caries diagnostics, emphasizing early detection of pathogenic oral microbiota. Rapid point-of-care assays capable of identifying high-density Streptococcus mutans are critical to enable targeted intervention. This pilot study evaluated the diagnostic validity of a high- threshold monoclonal antibody-based lateral flow assay (Saliva-Check Mutans, SCM) relative to selective culture for identifying clinically meaningful S. mutans loads in children. Stimulated saliva samples were collected from 50 schoolchildren aged 9-13 years in Oaxaca, Mexico. Samples were analyzed using SCM and selective culture on Mitis Salivarius Agar (MSA), with presumptive S. mutans colonies confirmed biochemically. Selective culture identified 46% of participants as positive, whereas SCM detected 18% as positive. Relative to culture, SCM demonstrated 39.1% sensitivity (95% CI: 21.5%-60.1%), 100% specificity (95% CI: 87.5%-100%), and 100% positive predictive value (95% CI: 66.4%-100%), with no false positives observed. The results highlight the assay's rule-in capability for high-density pathogenic loads (>10^5 CFU/mL). The diagnostic discordance reflects divergent analytical thresholds, termed the "Threshold Gap". While SCM exhibits limited sensitivity for low-level colonization, its absolute specificity supports its use as a precision high-threshold triage tool, identifying pediatric patients with clinically significant S. mutans burdens who may benefit from intensified preventive strategies. Integration with culture or molecular approaches can enhance risk stratification and precision dentistry workflows.