*3.2. Sequence Data Details*

Out of eight samples from the four subjects, 199,723 reads for denture plaque (min, max: 42,792, 54,898) and 210,750 for tongue coatings (45,193, 57,753) passed quality control. From these reads, sequences clustered into 15 phyla, 31 classes, 49 orders, 71 families, 142 genera, and 406 species. A heatmap of all 407 species detected in this study is shown in Figure S1. All sequence data are provided in the Supplementary Materials.

The ACE, Chao1, jackknife, Shannon, and Simpson alpha diversity indices were calculated to analyze the diversity and richness of all samples. By comparing the samples of denture plaque and tongues, the ACE, Chao1, jackknife, and Shannon indices were not significantly different (*P* > 0.05), proving that bacterial diversity and richness were similar in the samples collected from denture plaque and tongues. The values of these indices are shown in Table S1. Statistics of taxonomic assignment are shown in Table S2. A rarefaction curve is shown in Figure S2.
