Abstract
Enamel rods were morphologically classified by using human deciduous molar teeth. The samples were decalcified with lactic acid, doubly embedded in celloidin solution, sliced into cross sections, and stained with hematoxylin-eosin. They were observed under a light microscope. The sections were classified into four regions : surface, intermediate layer, deep layer and under pit and fissure. Arrangements of the enamel rods were classified into four patterns : stone-wall pattern, fish-scale pattern, pillar pattern and polygonal mixed pattern. The fish-scale pattern was observed most frequently, and the polygonal mixed pattern, least frequently. The structures of the enamel rod were classified into 20 shapes as follows : keyhole (types A, B and C), arcade, fan, diamond, horseshoe, tadpole, pentagon, hexagon, circle, oval, gothic arch, groove (types A, B, and C), trapezoid, squared, stick, and spade-shaped.
The surface of the enamel was darkly stained with hematoxylin ; the degree of staining gradually decreased deeper into the layer. In particular, the neonatal line was darkly stained by hematoxylin. In the head of the enamel rod, the enamel rod sheath was darkly stained and the central region of the enamel rod was lightly stained with hematoxylin. The tail of the enamel rod was darkly stained with hematoxylin. However, the results of staining on other enamel rods showed an opposite tendency, that is a light enamel sheath and tail and a dark central region.
