Researchers isolated the gene responsible for initiating normal tooth root formation in mammals and determined that tooth crown and root growth appear to be controlled by separate genetic processes, according to a study published in the February issue of Molecular and Cellular Biology.
Scientists from the State University of New York at Buffalo School of Medicine and Biomedical Sciences tracked the development of a laboratory mouse missing the gene responsible for encoding a protein known as nuclear factor I-C.
The nuclear factor I family of proteins is associated with the replication of adenoviruses, but the genes responsible for the development of the proteins exist only in multicellular organisms. This suggests a role in the development of complex life forms, said senior author Richard Gronostajski, Ph.D.
The mouse being studied appeared to develop normally until it was weaned to standard food. It then became stunted and died. Further investigation showed that the mouse had normal tooth crowns, but they lacked roots to embed the teeth into the jaw.
"The tooth is a little mini-organ that develops through a mechanism of its own," said Dr. Gronostajski. "The signals that are important for root growth turn out to be different from the signals that initiate crown growth. We don’t know if the defect affects the tooth itself and the signals between those two tissue layers, or if the signal originates in the surrounding tissue."
"This is the first mutation in mice that predominately affects the roots of teeth and how they grow out of the crown," he added. "If we can understand how this gene functions, we will know a great deal about root disease, root loss and the causes of tooth loss."
