Curtis A. Machida


Curtis A. Machida, PhD
1982, Oregon Health & Science University

Professor, Integrative Biosciences
Adjunct Professor, Pediatric Dentistry

Contributions to Science

Genetic Diversity and Emergence of Cariogenic Microorganisms in Caries-Active Children

Dental caries represents one of the most common chronic diseases affecting young children, and is a multi-factorial disease involving complex interactions of risk factors. The mutans streptococci (MS) group is among the major cariogenic microorganisms associated with dental caries. As our current focus, we propose to identify the microbial factors affecting the genetic diversity and potential selection of MS strains following caries restorative therapy in children. In prior work, we described genetic fingerprints of MS isolates (N=828) taken before and after treatment from children exhibiting severe early childhood caries (S-ECC). We have also identified the dominant MS genetic strains that occur within carious and non-carious sites within the oral cavity of individual patients (N=20), and have characterized strain cariogenicity properties. Our published studies have identified >55 MS genetic strains, and have found that caries restorative therapy in some patients results in population shifts to highly acidogenic or acid-tolerant MS strains, with single dominant MS strains appearing at 1-year post-therapy. The objectives of the current research program are to initiate a cohort of 200 patients where restorative and adjunctive therapy measures can be applied to ascertain selective effects, and develop a standardized genetic database of MS strains with defined cariogenic phenotypes that may serve as predictive microbial identifiers for dental caries and treatment outcomes.

Current Advisory & Editorial Board Memberships & Teaching Responsibilities

  • Member, Scientific Advisory Board, Journal of Endodontics
  • Member, Editorial Board, Molecular Biotech, Frontiers in Bioscience, Int J Biomed Sciences
  • Course Director, Integrative Biosciences 701, 702 and 703 (Teaching focus: Biochemistry)
  • Contributor, Mock NBDE Review Course (IB 705 –Review speaker in Biochemistry)
  • Member, Editorial Board, Oral Biology and Dentistry
  • Member, NIH ZRG1-MOSS-U82 Special Emphasis Panel (Oral and Skin Sciences)

Research Support

R15DE024317-01 and Supplement Award            Machida (PI)             09/15/14 –08/31/17
"Dominant Mutans Streptococci Genetic Strains in Caries-Active Children"
The significance of this project is to provide insight in the elimination and/or reduction of certain MS genetic strains in caries-active children relative to specific restorative and adjunctive therapy practices.

Representative Publications

1.    Li, H., V. Chen, Y. Chen, J. C. Baumgartner, and C. A. Machida. (2009). Herpesviruses in endodontic pathoses: Association of Epstein-Barr virus with irreversible pulpitis and apical periodontitits. J Endodontics 35(1):23-29. PMID: 19084119.

2.    Chen, V., Y. Chen, H. Li, K. Kent, J. C. Baumgartner, and C. A. Machida. (2009). Herpesviruses in abscesses and cellulitis of endodontic origin. J Endodontics 35(2):182-88. PMCID: PMC 2661131.

3.    Pellegrini, P., R. Sauerwein, T. Finlayson, J. Kimmell, D. Covell, Jr., T. Maier, and C. A. Machida. (2009). Plaque retention by self-ligating versus elastomeric orthodontic brackets: Quantitative comparison of oral bacteria and detection using ATP-driven bioluminescence. American Journal of Orthodontics and Dentofacial Orthopedics 135:426.e1-426.e9. PMID 193166769.

4.   Ton That, V., S. Nguyen, D. Poon, W. S. Monahan, R. Sauerwein, D. C. Lafferty, L. M. Teasdale, A. L. Rice, W. Carter, T. Maier, and C. A. Machida. (2010). Bioluminescent lux gene biosensors in oral streptococci: Determination of complementary antimicrobial activity of minocycline hydrochloride with the anesthetic lidocaine/prilocaine or the antiseptic chlorhexidine. In: Periodontitis: Symptoms, Treatment and Prevention. Nova Science Publishers, Inc.

5.    Fazilat, S., R. Sauerwein, J. Kimmell, T. Finlayson, J. Engle, P. Gagneja, T. Maier, and C. A. Machida. (2010). Application of ATP bioluminescence for quantification of plaque bacteria and assessment of oral hygiene in children. Pediatric Dentistry 32(3):195-204. PMID 20557702.

6.   Buck, T., P. Pellegrini, R. Sauerwein, D. C. Covell, Jr., T. Maier, and C. A. Machida. (2011). Elastomeric-ligated vs. self-ligating appliances: A pilot study examining microbial colonization and white spot lesion formation after one year of orthodontic treatment. Orthodontics: The Art and Practice of Dentofacial Enhancement 12(2):108-21. PMID 21935504.

7.    Palmer, E. A., T. Nielsen, P. Peirano, A. T. Nguyen, A. Vo, A. Nguyen, S. Jackson, T. Finlayson, R. Sauerwein, K. Marsh, I. Edwards, B. Wilmot, J. Engle, J. Peterson, T. Maier, and C. A. Machida. (2012). Children with severe early-childhood caries: Pilot study examining mutans streptococci genotypic strains after full-mouth caries restorative therapy. Pediatric Dentistry 34(2):e1-e10 (e- publication). PMCID: PMC3828076.

8.    Palmer, E. A., A. Vo, S. B. Hiles, P. Peirano, S. Chaudhry, A. Trevor, I. Kasimi, J. Pollard, C. Kyles, M. Leo, B. Wilmot, J. Engle, J. Peterson, T. Maier, and C. A. Machida. (2012). Children with severe early childhood caries: Mutans streptococci genetic strains persist one-year post-caries restorative therapy. J Oral Microbiol. Vol. 4 (e-publication). PMCID: PMC3523314.

9.    Gilbert, K. C., A. Sonesson, N. Nguyen, U. Nguyen, A. Vo, E. A. Palmer, T. Maier, and C. A. Machida. (2014). Mutans streptococci genetic strains in children with severe early childhood caries: Implications for caries incidence and treatment outcome. In: Epidemiology: Theory, Research and Practice. iConcept Press.

10.   Gilbert, K. C., R. Joseph, A. Vo, T. Patel, S. Chaudhry, U. Nguyen, A. Trevor, E. Robinson, M. Campbell, J. McLennan, F. Houran, K. Flann, M. Wages, E. A. Palmer, J. Peterson, J. Engle, T. Maier and C. A. Machida. (2014). Children with severe early childhood caries: Streptococci genetic strains within carious and white spot lesions. J Oral Microbiol. Vol. 6 (e-publication). PMCID: PMC 4216391.