I hear that the cure for tooth decay is Orajel, although I haven't tried it yet, since the last time I had a tooth ache was when I was like 12 years old. So I guess I should say that an ounce of prevention is worth a pound of cure. Brushing regularly really helps and the right diet too, that is, rich in vegetables and fruits, sweets only every now and then for special occasions or to reward yourself. Still, brushing before you go to bed cannot hurt.
One really strange tip that I came across comes from my former Croatian roommate Djani, who had a really severe tooth ache once. The drug store was closed at that time so he ended up talking to a security guard watching the door, who advised him to put a cigarette butt on the tooth that's hurting and you know what, Djani swore that it worked. He never asked me for help with a tooth ache ever again. I don't know how that did the job, but according to Djani, it might have to do with the bacteria in the compromised tooth or teeth. Something in the cigarette butt either kills or absorbs the micro-organisms. You may want to ask the dentist about it, though, just to be sure. Still, I can't forget the smile of relief from my roommate's face to this day.