Objective To explore the expression of salivary metabolites in patients with cavitated caries, and their relationship with caries activity.

Methods Ten cases of saliva samples were collected from 10 patients with cavitated caries cavitated group, and 10 health cases were selected as control group. The saliva samples in two groups were collected. The levels of salivary metabolites were detected by mass spectrometry to compare whether there were different metabolites between two groups (fold change ≥2, VIP≥1, P < 0.05) and diagnostic efficiency of the different metabolites. The MetOrigin and KEGG were used to analyze the origin and function of metabolites, respectively.

Results A total of 901 metabolites were detected in the saliva samples of two groups, and their origin included the host, microbe, drug, food, environment or co-metabolism. Compared with the caries-free group, the Exp group showed significantly different metabolite profiles. The 2-((2-ethylhexyl) oxy) carbonyl benzoic acid and L-homocitrulline were highly expressed (FC=29 707 and 5 057, P < 0.01), the expression levels of oxaloacetic acid, 2-phenylacetamide, DL-phenylglycine and glutamine-leucine-arginine were low in the Exp group (P < 0.01), the difference multiple was higher than 1 000, and the AUC value was higher than 0.9. The differential metabolites participated in the microbial metabolism and formation of secondary metabolites.

Conclusions There are different metabolic expression profiles between the Exp group and control group. The 2-((2-Ethylhexyl)oxy)carbonyl benzoic and L-homocitrulline are positively correlated with the caries, while the oxaloacetic acid, 2-phenylacetamide, 2-phenylglycine, Glu-Leu-Arg are negatively correlated with caries.