**5. Conclusions**

The oral microbiome was preserved in Japanese centenarians at the phylum level. At the species level, bacterial profiles were not consistent with other studies. *Firmicutes* and *Veillonella* were abundant phyla in both the plaque and the tongue. In the bacterial profile, bacteria formed clusters. The oral microbiome of the centenarian investigated in this study was similar to that of other age groups from previous studies at phylum level. Further study is needed to define a common bacterial profile at the species level.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2076-3417/10/15/5312/s1. Figure S1: Heatmap of all species detected. Figure S2: Rarefaction curve. Figure S3: Core heatmap. Table S1: Alpha diversity indices of different groups. Table S2: Statistics of taxonomic assignment. Table S3: Species detected in denture plaque and tongue. Sequence data: Sequence data of the eight samples. Dynamic pie chart: Dynamic pie chart of the bacterial profiles of samples. OTU data: OTU data used in this study.

**Author Contributions:** Y.N. planned the study design and management and analysis of the data and wrote the original draft. E.K., A.O., R.O., M.S., Y.T., C.T., and K.A. collected and managed the data. Y.N., H.D., T.S., and N.H. contributed to funding acquisition, planning the study design, and reviewing and editing the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was supported by JSPS KAKENHI (grant numbers 17K12030, 20K10303), SECOM Science and Technology Foundation, and an 8020 Research Grant for fiscal year 2017 from the 8020 Promotion Foundation (grant number 17–2–05). None of the funders played a role in the design of the study, data collection, analysis, interpretation of the results, or writing of the manuscript.

**Conflicts of Interest:** The authors state that they have no financial or nonfinancial conflict of interest regarding this research.
