1. SULIMAN ABDULLAH ALNUJAIDI - Consultant Endodontic, Al Yamamah Hospital, Ministry of Health, Riyadh, Saudi Arabia.
2. SULAIMAN ABDULLAH ALHOWAISH - Prosthodontist, Alyamamah Hospital, Riyadh, Saudi Arabia.
3. ABDULAZIZ YAHYA HOMADI - Medical Technologist, Laboratory Department, National Guard Hospital, Riyadh, Saudi Arabia.
4. ABDULELAH ALI ALHUSSINI - Laboratory Microbiology, Laboratory Department, National Guard Hospital, Riyadh, Saudi Arabia.
5. SALEH DAWOOD SALEH ALJAMHAN - Laboratory Microbiology, Laboratory Department, National Guard Hospital, Riyadh, Saudi Arabia.
6. SALEH NASSER SALEH ALRAWDHAN - Laboratory Microbiology, Laboratory Department, National Guard Hospital, Riyadh, Saudi Arabia.
7. BUSHRA ABDULRAHMAN ALGHAMDI - Dental Resident, Family Dentistry Department, National Guard Health Affairs, King Abdulaziz Medical City-Riyadh.
8. ABDULLAH HASSAN ALAMMARI - Dental Resident, Family Dentistry Department, National Guard Health Affairs, King Abdulaziz Medical City-Riyadh.
Saliva is an attractive diagnostic medium for oral diseases because it is non-invasive, inexpensive, and easy to collect at scale. This systematic review evaluated the diagnostic accuracy of salivary microbiological tests for periodontitis and dental caries. We searched MEDLINE (PubMed), Scopus, and Web of Science from inception to 26 October 2025 for original studies that measured salivary microorganisms against accepted clinical reference standards for periodontitis or caries. Twelve original studies met inclusion criteria (periodontitis, n=6, caries, n=6). For periodontitis, multiplex qPCR panels and 16S-based models showed good to excellent discrimination: area under the receiver operating characteristic curve (AUC) commonly ≥0.90 for multifeature indices, with sensitivity,specificity typically >80% in internal validation. Single-species cut-offs performed inconsistently. For caries, very high salivary Streptococcus mutans by culture predicted longitudinal caries progression in preschoolers, and several 16S, qPCR models discriminated severe early childhood caries with moderate-to-good accuracy. Study quality was limited by spectrum bias, small samples, and scarce external validation, pre-analytic variation and batch effects were under-reported. Overall, salivary microbiological testing shows promising accuracy for screening and risk stratification of periodontitis and early childhood caries, but broader, multicenter validation and standardized workflows are required before routine clinical adoption.
Saliva, Salivary Diagnostics, Oral Microbiome, Periodontitis, Dental Caries, qPCR, 16S rRNA Sequencing, Diagnostic Accuracy, ROC, Screening.