Carious status and supragingival plaque microbiota in hemodialysis patients Original paper

What was studied?

This study examined the carious status and supragingival plaque microbiota in hemodialysis patients, forming a clear microbiome signature of how chronic kidney disease affects oral ecology. This focus keyphrase—carious status and supragingival plaque microbiota in hemodialysis patients—anchors the investigation by integrating clinical dental assessments with 16S rRNA sequencing to characterize bacterial community shifts. The authors aimed to determine whether hemodialysis-related biochemical and physiological changes alter supragingival microbial composition in ways that elevate caries risk. The study scrutinized salivary chemistry, plaque diversity, and the abundance of key acidogenic and aciduric species to understand how the microbial ecosystem is reshaped in this medically complex population.

Who was studied?

The study included 30 adults with chronic kidney disease undergoing long-term hemodialysis and 30 age-, sex-, and smoking-matched healthy controls, each with at least 15 natural teeth. None had recent antibiotic exposure, diabetes, or acute oral disease. Hemodialysis patients demonstrated markedly altered systemic parameters—such as elevated serum creatinine, urea, and uric acid—and distinct salivary chemistry, including significantly elevated urea and pH but reduced calcium, all of which may drive microbial and caries-related changes.

Most important findings

The study revealed that hemodialysis patients exhibited significantly higher DMFT scores, driven largely by increases in decayed and missing teeth. Salivary urea and pH were elevated; however, the urea concentration (~0.12%) was insufficient to counteract acidogenic challenges, partly due to reduced salivary calcium and increased xerostomia. Microbiome sequencing demonstrated significantly reduced α-diversity and greater β-diversity dispersion, indicating a more unstable plaque ecosystem. Importantly, hemodialysis patients showed marked enrichment of key cariogenic taxa, including Streptococcus mutans, Streptococcus mitis, Lactobacillus salivarius, Lactobacillus fermentum, Lactobacillus vaginalis, Scardovia wiggsiae, and Actinomyces naeslundii. These species displayed both higher prevalence and relative abundance. Quantitative PCR confirmed higher S. mutans load. The microbial shift reflects a move toward an aciduric, acidogenic plaque community strongly associated with caries progression.

Key implications

The study establishes that hemodialysis patients experience a microbiome shift toward a cariogenic community, despite elevated salivary pH and urea. Low salivary calcium, high sugar intake frequency, xerostomia, and immune dysregulation collectively favor acid-tolerant species. This microbial signature underscores the need for intensified caries prevention in hemodialysis populations, including diet counseling, salivary flow support, and fluoride-based interventions. Notably, elevated oral Streptococcus mutans and Streptococcus mitis may increase systemic cardiovascular risk, given their documented presence in cardiac tissues—an important implication for clinicians managing medically complex patients.

Citation

Yue Q, Yin FT, Zhang Q, Yuan C, Ye MY, Wang XL, Li JJ, Gan YH. Carious status and supragingival plaque microbiota in hemodialysis patients. PLoS One. 2018;13(10):e0204674. doi:10.1371/journal.pone.0204674