Host Microbiome Interactions in the Oral Cavity of a Denture Wearer

Objectives: Currently there is limited understanding of how the composition of denture plaque directly influences denture related stomatitis (DS), and in turn the role of the host in this disease. Therefore, the aims of this study were to understand and compare the composition of plaque taken from different oral sites, including the denture, palatal mucosa and dental plaque from the mouths of denture wearers. Furthermore, to assess changes in the diversity and composition of the microbiome against increasing Candida CFU, as well as understanding the relationship between host antimicrobial peptides and denture plaque composition.
Methods: Samples were obtained from 131 denture wearers, all of which wore full or partially removable upper dentures. Swabs were taken of the palatal mucosa and the denture. If the patients had any natural teeth remaining, a sample of dental plaque was taken. Whole unstimulated saliva was obtained by expectorating into a collection tube. DNA was extracted from the denture plaque and amplicons were prepared and purified for MiSeq sequencing of the V4 region of 16S rRNA. Antimicrobial peptide (AMP) levels in patient’s saliva were assessed by ELISA.
Results: Over 550 OTU’s were identified across the three samples. Principal component analysis (PCA) demonstrated clear cluster differentiation between dental plaque and denture plaque. No significant differences in denture plaque composition was shown between health and disease, although on the mucosa significant differences were observed in terms of diversity. Higher levels of Candida spp. appear to induce a compositional switch to a more aciduric environment, where by Lactobacillus levels increased alongside Candida.
Conclusions: This is the first study to give a detailed insight into the microbiome of denture plaque in health and disease. Furthermore it has provided evidence that DS development is not solely a result of fungal infection, but somewhat of an interaction between the two kingdoms.