The United States Government Accountability Office (GAO) has issued a report on the Indian Health Service (IHS) credentialing of health care providers, including dentists.  GAO found that IHS didn't always fully follow the requirements for verifying health care professional qualifications, in part because IHS's guidance on how to do so was spread out across multiple, and sometimes conflicting, documents.  To read the GAO report on IHS health care provider credentialing, use the first link below.  To read GAO highlights of the report on IHS health care provider credentialing, use the second link below.
https://www.gao.gov/assets/d24106230.pdf  (GAO report on IHS health care provider credentialing)
https://www.gao.gov/assets/d24106230high.pdf  (GAO highlights on IHS health care provider credentialing)