Alterations in salivary profile in individuals with dental caries and/or obesity: A systematic review and meta-analysis

Objectives: To investigate current evidence on the association of salivary profile with dental caries and obesity.

Data/sources: A comprehensive search was conducted on PubMed, Web of Science, Embase, ProQuest Medical Database, ProQuest Sci-Tech Premium, and Cochrane Library up to June 2024. Observational studies comparing salivary profiles in individuals with dental caries and/or obesity were included. The risk of bias was evaluated using the Newcastle-Ottawa Scale. Meta-analysis was utilised to estimate the overall weighted or standardised mean differences (WMD or SMD).

Study selection: Fifty studies were included, comprising 47 cross-sectional studies and three longitudinal studies with only baseline data extracted. Meta-analysis demonstrated that individuals with caries had higher total antioxidant capacity (SMD: 1.78, P<0.001) and elevated levels of interleukin-6 (SMD: 3.41, P=0.004) and tumour necrosis factor-α (SMD: 0.61, P=0.005) in unstimulated whole saliva (UWS) compared to caries-free controls. Individuals with overweight/obesity, when compared to normal-weight counterparts, showed decreased UWS pH (WMD: -0.14, P=0.009), unstimulated and stimulated salivary flow rates (WMD: -0.09 mL/min, P=0.001 and WMD: -0.35 mL/min, P<0.001, respectively), phosphorus/phosphate levels in stimulated whole saliva (SWS) (SMD: -0.36, P=0.004), and peroxidase levels in both UWS (SMD: -1.56, P<0.001) and SWS (SMD: -1.10, P<0.001). Additionally, they exhibited higher salivary levels of mutans streptococci (SMD: 0.47, P<0.001), secretory immunoglobulin A (WMD: 14.51 μg/mL, P=0.020), and total antioxidant capacity in UWS (SMD: 0.67, P<0.001).

Conclusion: Although individuals with dental caries and/or obesity have altered salivary profiles, the quality of evidence remains low. Further high-quality studies are required to investigate the triadic associations in depth.

Clinical significance: Monitoring salivary parameters and biomarkers could serve as a relatively simple and non-invasive method for identifying, predicting, controlling, and monitoring individuals at high risk of dental caries and obesity. This knowledge can inform the development of tailored oral health promotion programs for individuals with obesity.