Influence of 8DSS peptide on nano-mechanical behavior of human enamel.

Aspartate-serine-serine (DSS) repeats are abundant in naturally occurring proteins that are critical for tooth formation. We recently developed octuplet repeats of aspartate-serine-serine (8DSS) peptides to promote the nucleation of calcium phosphate carbonate from free ions. In this paper, we report a possible role of 8DSS in promoting mineral deposition onto human enamel. Human enamel specimens were demineralized, exposed briefly to 8DSS solution, and then exposed to simulated body fluid that favors mineral deposition. At various stages of treatment, nano-mechanical behaviors, namely, hardness and elastic modulus, were determined by nano-indentation. Nano-indentation results showed that 8DSS treatment effectively improved the mechanical and elastic properties of demineralized enamel. The values of hardness and elastic modulus for the 8DSS-treated enamel were significantly higher than those of surfaces without 8DSS treatment. Furthermore, 8DSS peptides promoted the uniform deposition of nano-crystalline calcium phosphate carbonate over demineralized enamel surfaces and reduced surface roughness of demineralized enamel.