Non-toxic nail polish to break thumb-sucking habit?

[Anonymous]

My DD is 3.5 and is really doing a number on her teeth with her thumb-sucking. All the pleading, cajoling and bribes haven't worked so far to help her quit, and I am not interested in losing her trust by using bitters (or spices) on her thumb.

However, I think I've struck upon something. I told her that if she stops sucking altogether then we can paint her nails (a real treat for her, because I have not ever allowed that so far). My concern, though, is the toxicity of regular nail polish. Does anyone know of a nail polish for little girls that isn't as toxic as the stinky stuff we grown-ups use?

Alternative (and successful) ideas for ceasing thumb-sucking in a 3.5 year old also appreciated here.

Thanks.