hey garcia, I am not a dental student but I think I can help you out just a little bit. I work out as well, and have a pretty rough schedule even though I am not in dental school yet. However, the most important thing I believe is time management, and I am sure you know that. I have a couple of exercises you can use to fit a HECTIC schedule. Full body workouts for 3 days a week, or even 2 days a week for at least 45 minutes each day (this includes your conditioning, weightlifting all in one). Try to maintain a healthy diet and rest well, even though this might sound like while going to dental school. Meditation can definitely be an excellent stress reliever.
Another important thing you have to pay close attention to is adaptation. You have to learn to adapt to certain situations, even if this is out of the norm for you. It usually takes me about a week to get a new schedule going, but once it keeps going, then you are set.
BTW, I know a couple of medical/dental students who still work out, and they are doing great, so keep your head up. WORK HARD, EAT WELL, AND REST A LOT!