Nothing can be perfect and the product has to generate money regularly, so it would probably have to be something that requires reapplication every year or two. But that's a small flaw for a lot of perfect teeth. On a deeper level, another much more serious concern would be the public health safety concerns surrounding such technology. What are the potential health hazards of practical nanotechnology? If bad, are they really practical?
Currently there are very many nanoscale technologies that we use in our everyday lives such as Teflon, Gore-Tex, and carbon fiber to name a few. Those non-stick pans that are friends of the fried egg can be dangerous when more than medium heat is used as the heat burns the Teflon and lets off harmful fumes. Other surfactants like Gore-Tex can be found on your waterproof jacket. Carbon fiber, that expensive race car's hood and/or entire body.
So with the prevalence of such technologies, we have to wonder if they are safe in the long-term and worth using. If safe, great. If not, why isn't there more regulation and oversight of these products? is another question to consider. In the UK, DEFRA essentially did away with their nanotechnology oversight and the only US city looking at these technologies through regulation is Berkeley. What thoughts are out there? Will these innovations, possibly into health, only be a dream?