What Likkriue says is true if we are just talking about
jobs.
If you want to work for IHS as a dentist, whether through their loan repayment plan or just for your career, you don't have to be Native. They do have Indian Preference, though. So if a Native applies for the job and you apply for the job and you aren't Native, you won't get the job.
What Likkriue says is not true if we are talking about
scholarships.
To apply for the Indian Health Services scholarship for dental school you will be required to submit documentation that you are a member of a federally-recognized tribe or Alaskan village (that's what reservations/tribes are called in Alaska).
I think for pre-graduate or other undergrad specific scholarships you can be a descendent or member of state-recognized or terminated tribes, which requires some additional documentation.
If you aren't Native you can apply for the National Public Health Service Corps, where you can complete service on a reservation or in other government health care systems like a prison.
Source:
https://www.ihs.gov/scholarship/scholarships/
