Modification of calcium-phosphate coatings on titanium by recombinant amelogenin

Amelogenin proteins, the principal components of the developing dental enamel extracellular matrix, have been postulated to facilitate the elongated and oriented growth of the carbonated apatite crystals during enamel formation. We previously reported that amelogenin caused modulation of apatite crystals nucleated on a bioactive glass (Bioglass(R)) in vitro. Here, the effects of amelogenin on the growth morphology of calcium-phosphate crystals nucleated on a titanium surface were investigated in order to gain a better understanding of the role of amelogenins during enamel biomineralization and to explore their potential application in the design and development of novel biomaterials. The dose-dependent effects of a recombinant mouse amelogenin (rM179) were found to be different from those of bovine serum albumin, which significantly inhibited apatite crystal growth and caused the octacalcium phosphate (OCP) crystals to change from a plate-like shape to a curved shape, indicating a general inhibitory effect. The effects of rM179 on the crystal growth of OCP at 12.5-100 microg/mL and of apatite at 50 microg/mL were insignificant while the apatite crystals were remarkably elongated along their c-axes upon the use of 100 microg/mL of rM179. The unique modulation of the calcium-phosphate coatings on titanium by rM179 supports the view that amelogenins have a great potential for applications designed to develop novel biomimetic materials.