SuperC made a really good point, but the best point of all this is that you got your act together. Don't let the pass interfere with your future. Keep working hard, nothing is impossible, you might need a post-bach/masters but if it gets you to dental school, than it is worth fighting for.
Take a look at me for a example, in high school, I had 5 F's. I was going to the wrong direction and I felt lost, and I made an ever worst mystake by taking 2 years off school after I graduated from high school. I started working with construction... after those 2 years I was burned/tired, and just like you did, I started going into the right direction, got back in schools and working on my goals. My goal/dream is to become a dentist, and I am working/studying hard for my future to be bright. The past is the past man.
The best thing that someone can learn from experiences like this is not that they are getting good grades after they commit something wrong, is that they know the mystakes that they made, and they will know better next time they are faced with difficult decisions.
Good luck man, I am sure you'll make it, just keep your head up, don't let anyone push you back, focus on your goals.