Salivary profile and its correlation with dental caries and/or obesity

Abstract

Objectives: The relationship between dental caries and obesity has been studied for years. This systematic review aims to evaluate the associations of salivary profile and dental caries as well as obesity. Methods: A systematic search was conducted through six electronic databases (PubMed, Web of Science, Embase, Cochrane Library, ProQuest Medical Database, and ProQuest Sci-Tech Premium) from inception to November 2021. The studies were screened by two independent reviewers. Cross-sectional studies on salivary profile comparison among individuals with dental caries and/or obesity were included. For studies with sufficient homogeneity, quantitative synthesis was conducted. Results: Thirty-two studies were identified in the systematic review, and twenty studies were included for quantitative synthesis. Meta-analysis showed that significantly decreased unstimulated salivary flow rate (SMD -0.33; 95% CI -0.55, -0.11), stimulated salivary flow rate (SMD -1.21; 95% CI -1.85, -0.57) and pH in unstimulated whole saliva (SMD -0.89; 95% CI -1.36, -0.43) were observed in overweight/obese individuals compared to normal weight individuals. Significantly higher abundance of Mutans Streptococci (SMD 0.47; 95% CI 0.30, 0.64) and sIgA level (SMD 0.78; 95% CI 0.44, 1.12) were found in the saliva of overweight/obese individuals than those of normal weight individuals. Salivary interleukin-6, one of the adipokines in the human body, was increased significantly in individuals with dental caries compared to caries-free individuals (SMD 0.63, 95% CI 0.21, 1.05). Conflicting results exist in other parameters such as pH in stimulated whole saliva, salivary abundance of Lactobacilli, and salivary minerals. Conclusions: Overweight/obese individuals presented lower unstimulated and stimulated salivary flow rates, lower pH in unstimulated whole saliva, and higher salivary levels of Mutans Streptococci and sIgA, while individuals with dental caries presented elevated salivary interleukin-6. More in-depth studies are required to further evaluate the relationship between dental caries and obesity at salivary levels.