SCANNING ELECTRON-MICROSCOPY EXAMINATION OF RESORBING ENAMEL SURFACESIN UNEXFOLIATED PRIMARY MOLAR TEETH

We examined unexfoliated primary molar teeth by scanning electron micr oscopy to study the resorbing internal enamel surfaces. They were fixe d in a cacodylate buffered glutaraldehyde-formaldehyde mixture, treate d with 2 percent sodium hypochlorite, washed, dehydrated with ethanol and air-dried, before sputter-coating with a 40 nm layer of gold. The examination with a Jeol 6100 scanning electron microscope revealed lar ge areas of enamel resorption, characterized by closely adjoining hone ycomb-Like lacunae (concavities). In higher magnification, lacunae sho w enamel with various patterns of resorption: whereas in some regions, only the central portions of prisms are removed; in others, the prism sheath regions are seen below the other enamel structures. Also, regi ons showing a random pattern of resorption are observed. In addition, lacunae showing resorbing enamel prisms in longitudinal and other orie ntations are also observed. The results of the present study reveal, t herefore, that in unexfoliated primary teeth, the odontoclasts first r emove the coronal dentin and then reach and resorb large areas of enam el. Furthermore, the various patterns of resorption support the idea t hat removal of enamel by odontoclasts depends upon the orientation of enamel structures, rather than of the different degrees of mineralizat ion suggesting that enamel structures do not possess different inorgan ic/organic composition.