Host–microbiome interactions in apical periodontitis: The endodontic microbiome in relation to circulatory immunologic markers

Abstract

Aim: To explore microbial differences in the endodontic infection of teeth with primary or secondary apical periodontitis (AP), with or without symptomatology. Additionally, to investigate if these differences are depicted in immunologic markers in blood. Methodology: Twenty-nine teeth with primary or secondary AP were extracted and cryo-pulverized. Blood was drawn from the subjects at three different time-points before and three time-points after the extraction in a time period of four months. The V4 hypervariable region of the 16S rRNA gene was sequenced using Illumina MiSeq. The microbial profiles were ordinated using principal component analysis and tested for differences between groups with permutational multivariate analysis of variance using the Bray–Curtis distance. If significantly different, the microbial profiles were further analysed using the LDA effect size (LEfSe) biomarker discovery tool. A broad panel of inflammatory mediators in blood was examined longitudinally in all subjects during the six visits with mixed models. The Spearman correlation between these mediators and the zOTUs was calculated, and significant correlations (p