Enamel rod relations in the developing rat incisor.

Scanning electron microscopic and X-ray diffraction studies have shown that mandibular rat incisor teeth have two sets of rods which decussate at angles between 60 and 80% in both the most immature zone and the zone just beyond the opaque margin. A less well oriented interrod enamel component was found at right angles to both sets of rods. The information provides additional views of this complex tissue. Furthermore, it has been shown that the Wistar rat incisal enamel ultrastructure facilitates the use of X-ray diffraction to determine molecular relations between the crystals and matrix constituents as the rods are not all at 90 degrees to one another.