What can I do to help my boyfriend overcome his fear of the dentist?

My boyfriend is stubborn. This is not my problem but it has to do with my problem. I love him dearly, but, he has terrible teeth. And by terrible I mean revolting to the point where I don’t want to kiss him or be near enough to smell his nasty breath. It’s harsh, I know, but it’s true. For the past three years he has been telling me he will go to the dentist and get his teeth fixed, etc. But he never does. He only tells me to appease me and then never does a damn thing about it. He is crippled with a fear of the dentist and it stresses him out very badly to even think of it. Any time I bring it up he immediately shuts down and doesn’t talk to me. I’ve tried being supportive and compassionate; it doesn’t work. I’ve tried being mean and a huge bitch; it doesn’t work. I’m not just worried about the vanity part of it, there are serious health issues he is at risk for by keeping his teeth in this state and letting them decay even further. I don’t know what to do, I’m at the end of my rope and I feel sick with worry. Help.