Study on pathogenic mechanisms of metabolic pathways and key metabolites associated with black stain with or without severe early childhood caries.

OBJECTIVE

To investigate dental plaque metabolic profile differences between preschoolers with Black Stain and Caries-free (BSCF) versus Severe Early Childhood Caries with Black Stain (SECCBS) to elucidate S-ECC pathogenesis.

DESIGN

Dental plaque was collected from 59 preschoolers aged 3-6 (BSCF, n = 29; SECCBS, n = 30) and analyzed using ultra-high performance liquid chromatography-tandem mass spectrometry. Differential metabolites (DMs) were identified via partial least squares discriminant analysis. KEGG pathway analysis and Metorigin provided functional and source-tracking insights. Weighted Gene Co-expression Network Analysis (WGCNA) identified hub metabolites linked to clinical traits, while 10 machine learning models were developed for diagnostic prediction.

RESULTS

Profiling identified 1069 metabolites, predominantly lipids/lipid-like molecules (24.60%) and organic acids/derivatives (11.51%). Eighty-five DMs were identified between groups; four were significantly downregulated ( Δ17-6-keto prostaglandin F1α, VLH, DPK, and N'-[1-(2-hydroxyphenyl)ethylidene]-3-methoxybenzohydrazide). L-glutamate was significantly upregulated in SECCBS, whereas L-(+)-citrulline was downregulated. KEGG analysis mapped DMs primarily to nucleotide, carbohydrate, amino acid, and lipid metabolism. Metorigin revealed 78.6% of metabolites were co-derived from diet, microbiota, and pharmaceuticals. WGCNA identified 31 modules, two positively correlating with SECCBS. The top-performing machine learning model achieved robust AUC performance for clinical stratification.

CONCLUSIONS

Distinct plaque metabolomic profiles differentiate SECCBS from BSCF. Alterations in nucleotide metabolism, the pentose phosphate pathway, and specific amino acid pathways drive SECC progression. Furthermore, 2'-deoxyuridine and 6-phosphogluconic acid emerge as potential biomarkers for early SECC diagnosis, prevention, and targeted clinical intervention.