Co-occurrence of yeast, streptococci, dental decay, and gingivitis in the post-partum period: results of a longitudinal study

<b>Objective</b>: The interactions between yeast and streptococci species that lead to dental decay and gingivitis are poorly understood. Our study describes these associations among a cohort of 101 post-partum women enrolled in the Center for Oral Health Research in Appalachia, 2012-2013. <b>Methods</b>: All eligible women without dental caries were included (n = 21) and the remainder were randomly sampled to represent the total number of decayed, missing, and filled teeth (DMFT) at enrollment. We used amplicon sequencing and qPCR of saliva from 2, 6, 12 and 24 visits to determine microbiome composition. <b>Results</b>: Active decay and generalized gingivitis were strongly predictive of each other. Using adjusted marginal models, <i>Candida albicans</i> and <i>Streptococcus mutans</i> combined were associated with active decay (OR = 3.13; 95% CI 1.26, 7.75). However, <i>C. albicans</i> alone (OR = 2.33; 95% CI: 0.81, 6.75) was associated with generalized gingivitis, but <i>S. mutans</i> alone was not (OR = 0.55; 95% CI: 0.21, 1.44). Models including microbiome community state types (CSTs) showed CSTs positively associated with active decay were negatively associated with generalized gingivitis. <b>Discussion</b>: <i>C. albicans</i> is associated with active decay and generalized gingivitis, but whether one or both are present depends on the structure of the co-existing microbial community.