The Impact of the Eda Pathway on Tooth Root Development

The Eda pathway (Eda, Edar, Edaradd) plays an important role in tooth development, determining tooth number, crown shape, and enamel formation. Here we show that the Eda pathway also plays a key role in root development. Edar (the receptor) is expressed in Hertwig’s epithelial root sheath (HERS) dur...

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Bibliographic Details
Published in:Journal of dental research 2017-10, Vol.96 (11), p.1290-1297
Main Authors: Fons Romero, J.M., Star, H., Lav, R., Watkins, S., Harrison, M., Hovorakova, M., Headon, D., Tucker, A.S.
Format: Article
Language:English
Subjects:
Adapter proteins
Adolescent
Animals
Child
Defects
Dental enamel
Dental pulp
Dental Pulp Cavity - abnormalities
Dental roots
Dentistry
Ectodysplasins - genetics
Enamel
Humans
Ligands
Male
Mesenchyme
Mice
Molar - abnormalities
Molar - embryology
Molars
Mutation
Odontogenesis - genetics
Phenotype
Phenotypes
R&D
Research & development
Research Reports
Signal Transduction
Teeth
Tooth Abnormalities - genetics
Tooth Root - abnormalities
Tooth Root - embryology
X-Ray Microtomography
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Summary:The Eda pathway (Eda, Edar, Edaradd) plays an important role in tooth development, determining tooth number, crown shape, and enamel formation. Here we show that the Eda pathway also plays a key role in root development. Edar (the receptor) is expressed in Hertwig’s epithelial root sheath (HERS) during root development, with mutant mice showing a high incidence of taurodontism: large pulp chambers lacking or showing delayed bifurcation or trifurcation of the roots. The mouse upper second molars in the Eda pathway mutants show the highest incidence of taurodontism, this enhanced susceptibility being matched in human patients with mutations in EDA-A1. These taurodont teeth form due to defects in the direction of extension of the HERS from the crown, associated with a more extensive area of proliferation of the neighboring root mesenchyme. In those teeth where the angle at which the HERS extends from the crown is very wide and therefore more vertical, the mutant HERSs fail to reach toward the center of the tooth in the normal furcation region, and taurodont teeth are created. The phenotype is variable, however, with milder changes in angle and proliferation leading to normal or delayed furcation. This is the first analysis of the role of Eda in the root, showing a direct role for this pathway during postnatal mouse development, and it suggests that changes in proliferation and angle of HERS may underlie taurodontism in a range of syndromes.
ISSN:0022-0345
1544-0591
DOI:10.1177/0022034517725692