By Kirstie Saltsman, Ph.D. | October 27, 2014
Finger-like projections (magenta) into a tooth’s top layer represent damage to the enamel of a person with a keratin 75 mutation.
Finger-like projections (magenta) into a tooth’s top layer represent damage to the enamel of a person with a keratin 75 mutation. (Duverger et al., JCI 2014)

Keratins are proteins that are key structural components of hair, nails, and the skin’s outer layer. Now, new research led by Maria Morasso, Ph.D., chief of the Laboratory of Skin Biology at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), has shown that certain types of hair keratin also help form dental enamel, the tough outer covering of teeth. The study appeared online October 27, 2014, in The Journal of Clinical Investigation.

Following up on an observation in mice suggesting that some types of hair keratin are also produced in developing teeth, Morasso’s team set out to uncover the role these proteins play in tooth structure. The researchers focused on one of these proteins, keratin 75, because mutations in its gene had been linked to certain hair disorders, such as shave bumps, a condition in which shaving causes ingrown hairs and persistent skin irritation.

Curious if these same mutations would also affect the integrity of tooth enamel, Morasso’s team, in collaboration with investigators at the University of Pittsburgh, examined the teeth of 706 adults and 386 children and found that the mutations in keratin 75 correlated with increased numbers of cavities. Further investigation revealed evidence of altered enamel structure and reduced enamel hardness in people with one of these mutations, suggesting that keratin 75 plays an important role in enamel formation.

By uncovering a role for hair keratins in dental enamel structure, this work may lead to new strategies for combating tooth decay, one of the most prevalent health problems worldwide.

NIAMS researcher Maria Morasso, Ph.D., describes what we know of keratin 75’s involvement in dental enamel formation, and how this information may be used to improve dental health.
NIAMS research Olivier Duverger, Ph.D., describes the role of keratins in tooth and hair structures.

This work was supported by the NIAMS intramural program under project number ZIAAR041171-07. Support was also provided by the NIH’s National Institute of Dental and Craniofacial Research (grants R01-DE014899, U01-DE018903 to M. Marazita and R56-DE016703 to E. Beniash).

Duverger O, Ohara T, Shaffer JR, Donahue D, Zerfas P, Dullnig A, Crecelius C, Beniash E, Marazita M, Morasso MI. Hair Keratin Mutations in Teeth Increase Risk for Dental Caries. JCI 2014 Oct 27 Vol (issue): pp-pp

The mission of the NIAMS, a part of the U.S. Department of Health and Human Services' National Institutes of Health, is to support research into the causes, treatment and prevention of arthritis and musculoskeletal and skin diseases; the training of basic and clinical scientists to carry out this research; and the dissemination of information on research progress in these diseases. For more information about the NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS website at

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