Ecological DentistryOral Ecology and Biochemistry

Continually moistened with saliva, the oral cavity is made of various soft and hard tissues, such as teeth, gingiva and the tongue, and is the pathway of foods to enter the body. In addition, a tremendous number of microorganisms inhabit there in the form of oral microbiome (or oral microbial flora). The oral cavity forms an ecosystem where the host (humans) and oral microbiome cohabit. Disruption of balance of this healthy oral ecosystem leads dental caries, oral malodor and periodontal diseases. In recent years, the oral microbiome has been found to be associated with systemic disease and health.

Using leading-edge techniques of molecular biology, anaerobic experimental systems and the notion of "omics", we conduct research on the role of oral microbiome in oral health and disease from an oral ecosystem viewpoint. In addition, we propel clinical research on caries-preventive effects of xylitol, fluoride etc, and on microbiome-caused degradation of biomaterials. As for research close to our everyday life, we evaluate cariogenicity of food products and provide the information to the society through governmental agencies. In addition, we have begun to study the impact of metabolites from the oral microbiome on the whole body. We are also conducting research on the metabolism of cancer cells which exhibit a similarity to microbiome-constituting bacteria.

Oral and systemic health depends on a healthy symbiosis between the host and the oral microbiome. Through research on our symbiotic partners (microbiome), the Division of Oral Ecology and Biochemistry is aiming to improve and preserve oral health. We boast a healthy and cooperative atmosphere with a wide diversity of students coming from such fields as nutrition management, pharmacology, medical technologist and, of course, dentistry.


Topics of Research

  • Genomics, proteomics and metabolomics of oral microbial ecosystem (oral microbiome)
  • Metabolism of oral microorganisms using an anaerobic experimental system and the association with systemic / oral health and diseases
  • Caries / Periodontitis preventive properties of fluorides, sugar alcohols and tea catechins
  • Evaluation of cariogenic potential of food products and sweeteners using pH-telemetry
  • Oral microbiome-induced deterioration of dental biomaterials
  • Metabolism of host cells, including oral cancer cells

Recent Publications

  1. Han S, Washio J, Abiko Y, Zhang L, Takahashi N.
    Green Tea-Derived Catechins Suppress the Acid Productions of Streptococcus mutans and Enhance the Efficiency of Fluoride.
    Caries Res. 2023;57(3):255-264. doi: 10.1159/000534055.
  2. Sakurai I, Mayanagi G, Yamada S, Takahashi N.
    In situ detection of endogenous proteolytic activity and the effect of inhibitors on tooth root surface.
    J Dent. 2023 Apr;131:104471. doi: 10.1016/j.jdent.2023.104471.
  3. Huang G, Chen S, Washio J, Paka Lubamba G, Takahashi N, Li C.
    Glycolysis-Related Gene Analyses Indicate That DEPDC1 Promotes the Malignant Progression of Oral Squamous Cell Carcinoma via the WNT/β-Catenin Signaling Pathway.
    Int J Mol Sci. 2023 Jan 19;24(3):1992. doi: 10.3390/ijms24031992.
  4. Liu S, Washio J, Sato S, Abiko Y, Shinohara Y, Kobayashi Y, Otani H, Sasaki S, Wang X, Takahashi N.
    Rewired Cellular Metabolic Profiles in Response to Metformin under Different Oxygen and Nutrient Conditions.
    Int J Mol Sci. 2022 Jan 17;23(2):989.
  5. Shinohara Y, Washio J, Kobayashi Y, Abiko Y, Sasaki K, Takahashi N.
    Hypoxically cultured cells of oral squamous cell carcinoma increased their glucose metabolic activity under normoxic conditions.
    PLoS One. 2021 Oct 22;16(10):e0254966.
  6. Tagaino R, Washio J, Otani H, Sasaki K, Takahashi N.
    Bifacial biological effects of ethanol: acetaldehyde production by oral Streptococcus species and the antibacterial effects of ethanol against these bacteria.
    J Oral Microbiol. 2021 Jun 9;13(1):1937884.
  7. Han S, Abiko Y, Washio J, Luo Y, Zhang L, Takahashi N.
    Green Tea-Derived Epigallocatechin Gallate Inhibits Acid Production and Promotes the Aggregation of Streptococcus mutans and Non-Mutans Streptococci.
    Caries Res. 2021;55(3):205-214.
  8. Sato-Suzuki Y, Washio J, Wicaksono DP, Sato T, Fukumoto S, Takahashi N.
    Nitrite-producing oral microbiome in adults and children.
    Sci Rep. 2020 Oct 6;10(1):16652.
  9. Wicaksono DP, Washio J, Abiko Y, Domon H, Takahashi N.
    Nitrite Production from Nitrate and Its Link with Lactate Metabolism in Oral Veillonella spp.
    Appl Environ Microbiol. 2020 Oct 1;86(20):e01255-20. doi: 10.1128/AEM.01255-20.
  10. Kameda M, Abiko Y, Washio J, Tanner ACR, Kressirer CA, Mizoguchi I and Takahashi N: Sugar Metabolism of Scardovia wiggsiae, a Novel Caries-Associated Bacterium. Front. Microbiol. 2020. 11:479.
  11. Nyvad B, Takahashi N: Integrated hypothesis of dental caries and periodontal diseases. J Oral Microbiol. 2020 Jan 7;12(1):1710953. doi: 10.1080/20002297.2019.1710953. eCollection 2020. Review.
  12. Tagaino R, Washio J, Abiko Y, Tanda N, Sasaki K, Takahashi N: Metabolic property of acetaldehyde production from ethanol and glucose by oral Streptococcus and Neisseria. Sci Rep. 2019 Jul 18;9(1):10446.
  13. Manome A, Abiko Y, Kawashima J, Washio J, Fukumoto S, Takahashi N: Acidogenic Potential of Oral Bifidobacterium and Its High Fluoride Tolerance. Front Microbiol. 2019 May 16;10:1099.
  14. Ishiguro T, Mayanagi G, Azumi M, Otani H, Fukushima A, Sasaki K, Takahashi N: Sodium fluoride and silver diamine fluoride-coated tooth surfaces inhibit bacterial acid production at the bacteria/tooth interface. J Dent. 2019 May;84:30-35.
  15. Fukushima A, Mayanagi G, Sasaki K, Takahashi N: Corrosive effects of fluoride on titanium under artificial biofilm. J Prosthodont Res 62(1): 104-109, 2018.
  16. Morishima H, Washio J, Kitamura J, Shinohara Y, Takahashi T, Takahashi N: Real-time monitoring system for evaluating the acid-producing activity of oral squamous cell carcinoma cells at different environmental pH. Sci Rep 7(1): 10092, 2017.
  17. Mayanagi G, Igarashi K, Washio J, Takahashi N: pH Response and Tooth Surface Solubility at the Tooth/Bacteria Interface. Caries Res 51(2): 160-166, 2017.
  18. Yamamoto Y, Washio J, Shimizu K, Igarashi K, Takahashi N: Inhibitory Effects of Nitrite on Acid Production in Dental Plaque in Children 15(2): 153-156, 2017.
  19. Washio J, Ogawa T, Suzuki K, Tsukiboshi Y, Watanabe M, Takahashi N: Amino acid composition and amino acid-metabolic network in supragingival plaque. Biomed Res 37(4): 251-7, 2016.

Laboratory Contacts