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ENAMEL. 107

height of the cusps; the higher the cusp the greater the inclination from
the axial plane. Fig. lingual section of a superior bicuspid, shows the plan of arrangement
and illustrates the arch principle in the construction.

Fig. 89.

Stratification of enamel ; the cusp of a bicuspid: Dc, di.uio-Liiaii,> ; ,..1.. ;,..i. l...i. i ...unci defect
showing in the lieavy stratification band; If/, interglobular spaces in the dentin. (About,
lOX.)
In the study of longitudinal sections of the teeth, one of the most
conspicuous structural features is the stratification bands, or brnvm
bands of Retzinx. These bands are not parallel with cither the outer
surface of the enamel or the dento-enamel junction. They begin at the
tip of the dentin cusps and sweep around in larger and larger zones.
These stratification bands are better seen in comparatively thick sec-
tions, and are caused by the varying amount of pigment deposited with