it's not unique to just kool smiles. >> it's a medicaid goldmine, and they're drilling for your tax dollars. >> o'brien: another private equity backed kids dental chain, small smiles, was the subject of this 2010 report that led to a 24 million dollar settlement with the federal government. now, corporate dental chains have become the subject of a senate investigation. >> when private equity firms get involved, you've got to understand that their motivation is to make money. >> o'brien: senator charles grassley says it's tough for the government to encourage providers on the one hand and protect patients on the other. >> we had whistleblowers that came to us and gave us information of what they thought was not only bad dentistry delivery and bad health care, but also a waste of taxpayers' dollars. >> o'brien: are profits and patient care always at odds, you think? >> well, to some extent, yes. there ought to be complete, good relationships between the patient and their dentist. they ought to know that the only person that that dentist is concerned about is the patient. and that's not what i