Wow, what an interesting thread... I know it's old, but it's a conversation worth bumping.
I've taken two trips abroad to volunteer, although neither were dental. I HIGHLY recommend anyone to invest the time and money... HIGHLY. If you're anything like me or everyone else I know that went, it will change your entire perspective. You might even be surprised when you discover you're more culture shocked coming back to the US!
About the money issue that the OP touched on: Yea, it's more expensive than you'd initially think, but there is an obvious reason for this... it's a donation. These programs need money more than they need your presence (especially if you're not trained). The experience is worth the cost! However, there are much cheaper programs than the OP noted. In fact, 3 grand sounds suspicious.
-One of the organizations I volunteered with charged per day. They had short, medium, and long-term rates depending on the overall length of stay, which were $25, $10, and $5 per day. Those rates are cheaper than my rent! It's also important to remember that your plane ticket and your fee/donation are the only costs you will incur... once you're there, it's practically a free ride!
Where to go: VIDA looks very cool, and I'd consider contacting them for more information. But anyone interested in exploring their options should check out idealist.org! This is a great resource for tons of intl nonprofit programs (as well as domestic ones). You can search by types of services, location, etc.
-I know that I am not the type of person to join a big program like PeaceCorp or Habitat for Humanity. It's just not my style. My two trips were done independently with very small organizations. Idealist.org is a great resource to find what type of program matches you. For example, one program I saw on idealist had a medical/dental clinic to support their broader "save our rainforest" program. How cool would it be to get involved with both!!?
Ethics: Doctoothache has some pretty good points on what you should and shouldn't do, but I hope he doesn't dissuade anyone from taking the opportunity to volunteer abroad. Yea, things are different abroad. Ethics isn't as big of a concern, but it should be! Of course you're always responsible for your morals and values where ever you are. Doc doesn't say so outright, but his postings might leave some readers worried that adcoms will assume that because you volunteered abroad you unethically practiced dentistry without a license! Not true, it's very respectable!!
-One of my two experiences was in a psychiatric ward and outpatient clinic, which I did before graduating college. All the doctors did down there was push meds without any therapy! After the 2nd day, the head psychiatrist introduced me to a patient saying, "this is our resident psychologist. He is going to take you to his office and practice his therapies on you now." I probably dropped my jaw on the floor. Rather than pretend that I was qualified to do this, I focused on educating the patients. I told them the importance of seeking proper counseling in addition to their prescriptions. My point: I flipped a potentially dangerous situation into an opportunity to really help out, and I think it reflects a lot of responsibility to adcoms.
so yea, Volunteer Abroad! Look into it. I dream of going back but have been procrastinating for years now. Maybe I'll sign up for VIDA and hop on another program down there when VIDA ends (two weeks is too short for me 😀)