I agree with Dara. List the experiences and be prepared for the following questions...
Why did you volunteer in this setting?
Why did you choose medicine over dentistry?
Are you also applying to dental schools? (I am not sure if this would be legal, but it is likely to come up)
If you get accepted into both a dental school and our school, which would you attend...
etc...
Write down anything meaningful on your application, just be prepared to talk about it.