From Thermal Springs to Saline Solutions: A Scoping Review of Salt-Based Oral Healthcare Interventions

Background: Therapeutic applications of saline solutions in oral healthcare range from mineral waters to standardized sodium chloride preparations. Despite widespread traditional use, their scientific foundation remains inadequately characterized. This scoping review aimed to systematically map the available evidence for salt-based oral health interventions, characterize study populations and outcomes, and identify research gaps to guide future investigations. Methods: Following JBI methodology and PRISMA-ScR guidelines, four electronic databases (PubMed, Scopus, Web of Science, and Cochrane Library) were systematically searched for publications from 2000 to 2025. Studies were classified along a spectrum from geological mineral waters to artificial preparations. Narrative synthesis was employed with systematic gap identification. Results: Seventeen studies met inclusion criteria, with a median sample size of 41 participants and a median follow-up of 4 weeks. Evidence distribution revealed concentration on hypersaline Dead Sea derivatives (n = 7, 41%) and European thermal waters (n = 5, 29%), with limited representation of marine-derived (n = 1, 6%) and simple saline solutions (n = 3, 18%). Reported outcomes included periodontal parameters, xerostomia symptoms, viral load, mucositis severity, and dentin hypersensitivity, with variable methodological quality across studies. Heterogeneity in interventions, comparators, and outcome measures precluded direct comparisons. Conclusions: The current evidence base for salt-based oral interventions remains limited and methodologically heterogeneous. While preliminary findings suggest potential applications across multiple clinical domains, small sample sizes, short follow-up periods, and inconsistent outcome measures preclude definitive recommendations. Standardized protocols and adequately powered trials are needed before evidence-based clinical integration.