Ultrastructural study on the interface between the original enamel and fluorapatite formed upon the tooth surface

Abstract

There have been few reports addressing the state of bond between synthesized fluorapatite on the enamel by the gel method and the existing enamel. The purpose of the present study is to examine the ultrastructure of the interface between the existing enamel and synthesized fluorapatite. The results are as follows.

• 1. Scanning electron microscopy revealed a distinct border between synthesized fluorapatite and the existing enamel surface. Observation after acid erosion showed the evidence of demineralization at the interface.

• 2. Transmission electron microscopy identified two distinct patterns at the interface between large fluorapatite crystals and the enamel surface: one involving a gap and the other with a direct contact. Synthesized fluorapatite and the enamel were separated by an intercalated layer of small immature crystals.

• 3. Most of synthesized fluorapatite crystals were positioned vertically to the enamel surface and some were oriented irrespective of the enamel surface.

Form these results, the bond between synthesized fluorapatite and the existing enamel seems to be weak, because of the presence of an intercalated layer of small immature crystals.