**10. Conclusions and Future Perspective**

In this review, we explored the close relationship between oral microbiomes and host health. The novel technological advances in sequencing have greatly accelerated our ability to identify the microbiomes present in clinical samples taken from the oral cavity at the species level. The accumulation of knowledge about oral microbiomes is driving this research in new directions, and extended analysis of transcript (transcriptome), protein (proteome), and metabolic products (metabolome) provides insight into host–microbial interaction in oral and systemic diseases. The current state of this oral microbiome research, which has been reported so far, shows that oral diseases are complex diseases reflecting changes in microbial components and host immune responses, and are interrelated with systemic health. The combined study with multi-omics data from a host and their microbiome will facilitate advances in personalized medicine (Figure 4).

**Figure 4.** Personalized medicine with host–microbiome combined analysis.

**Author Contributions:** Conceptualization, Y.-D.C. and Y.-J.S.; methodology, Y.-D.C. and Y.-J.S.; software, Y.-D.C. and K.-H.K.; validation, Y.-D.C., K.-H.K., and Y.-J.S.; investigation, Y.-D.C. and Y.-J.S.; resources, Y.-D.C. and Y.-J.S.; original draft preparation, Y.-D.C. and Y.-J.S.; review and editing, Y.-D.C. and Y.-J.S.; supervision, Y.-M.L., Y.K., and Y.-J.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF-2020R1A2C1007536/2020R1C1C1005830).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors report no declarations of interest.
