Well I live in California where everybody's expected to have perfect teeth. So many guys would never date somebody with bad teeth. But given my bad teeth, I have to say that there have been a few wonderful guys in the past few years who nevertheless have made it clear that they were interested and thought I was attractive regardless. But I have been the one unable to deal with intimacy, so I have put them off. I think if you have bad teeth, a large percentage of people will write you off, but there will always be some wonderful people who see you for who you are - but you have to be ready for them. I'm not, because I have always been better at dealing with problems on my own, so I'd rather deal with my teeth first, then I will feel ready to be intimate and open in a relationship. I just know I need to be in control of the timing and circumstances of my dental treatment, and then after I will feel more ready to invite somebody to be close to me.
So long answer, but yes, it definitely has affected my dating life, and yes it sucks, but it will improve eventually. There are some wonderful people out there (and also some shallow people who would never accept anyone with a 'defect' but don't let that form your opinions of the world in general.)