Binding Ability of Amelogenin to Fluorotic and Nonfluorotic Enamel Crystals

The systemically administered fluoride at high concentrations increases the surface roughness of developing enamel crystals. Objectives: The aim of this study was to investigate whether the binding of the most abundant enamel protein paralleled the fluoride dose dependent roughness of rat enamel crystals. Methods: The maturation-stage enamel crystals obtained from rats fed 0 ppmF, 50 ppmF, 75 ppmF in the drinking water were isolated and enamel matrix proteins bound to the crystal surface were removed. The recombinant mouse amelogenin was allowed to interact with the crystals for 2 min. After binding the amelogenin to the crystals, the crystal surface roughness was measured using the atomic force microscope. Results: The surface roughness analyses R(a), of the control, 50 ppm, and 75 ppm crystals are 1.05 nm, 1.23 nm, 1.71 nm respectively. The 75 ppm fluorotic crystals are significantly rougher than the control and the 50 ppm fluorotic crystals (p<0.05). The 50 ppm crystals are also rougher than the control ( p<0.05). Conclusions: This finding shows that the binding of amelogenin did parallel the dose dependent roughness of the rat enamel crystals. It also suggests that the greater binding ability of the fluorotic enamel crystals may prevent stripping of the enamel matrix proteins during enamel development resulting in rougher crystal surfaces. Supported by US PHS Grant DE015599 (NIDCR), IADR.CED Visiting Scholar Stipend.