Women in Japan, in general (in the city) have anything from *perfectly* straight and white teeth, to some of the most rotten grey, decaying excuses for teeth you've ever seen. The majority in my experience though, are... lets just say... slightly crooked/off white/fake (fake as in they've had caps done etc).
How do Japanese women react when we approach them? Some are extremely favourable, while others are indifferent, while others again are downright snobs.... much like any country really. I've been here long enough to realize that Western Caucasian Males are NOT always what Japanese women want...
As far as hooking up with a Japanese chick is concerned, either try your luck with some Japanese tourists where you are, or come to Japan and try your luck here?