Okay, I've changed a couple of things again. Eyeball and teeth diffuse colors changed as suggested by face_off. Inverse of Jessi's default teeth texture used as bump map. Glossy node used as alternate specular on teeth (still not too happy with anisotropic). Direction of main light changed slightly. Back light from the right rather than main light used for the realism kit blushing effect.

This is again a piece of the unpostworked render. The full image with some mild postwork can be seen in my gallery. I've decided to give the subject a rest because and some point it gets boring to keep fiddling with tiny details in the same old image. But that doesn't mean that I'm not open for further suggestions and experiments. Only that I'm now quite happy with the teeth and will reserve further insights for use in other work.

Thanks for all the input so far.

-- I'm not mad at you, just Westphalian.