Background
Fluorapatite-coated materials have potential application for dental and medical implants. In tooth development, the prism-like structure in enamel is thought to be created by the cells and proteins involved in enamel formation and maturation. This study investigated whether the substrate itself on which the films are grown, without the inclusion of cells or proteins, may affect their crystal alignment and three-dimensional morphology.
Material and Method
Human dentin/enamel junction (DEJ), dentin, stainless steel plates, etched stainless steel plates, etched titanium plates, glass, and mica were used as substrates to grow fluorapatite (FA) crystals using a hydrothermal method. FA crystal growth on these substrates was observed using scanning electron microscopy.
Results
Under hydrothermal conditions, enamel prism-like structure could not be seen when the crystals were grown on mica or glass. Organized bundles of FA were created using DEJ, but not dentin, although it supported crystal growth. Etched stainless steel and titanium supported the growth of aligned FA crystals, but without the prism structure.
Conclusions
The surface properties of the substrate on which the nanocrystals grow appear to affect their alignment, organization, and consequently the formation of a prism structure.

Keywords: Stainless Steel - chemistry, Nanotubes - ultrastructure, Molar, Microscopy, Electron, Scanning, Materials Testing, Glass - chemistry, Dental Enamel - chemistry, Dentin - chemistry, Crystallization, Apatites - chemistry, Aluminum Silicates - chemistry, Acid Etching, Dental, Surface Properties, Titanium - chemistry