this question was asked about ten months ago... link

I'll post my response again for completion sake:

In 1926 the Carnegie Foundation for the Advancement of Teaching was publishing studies on professional education in the United States. One of those was about dentistry and war written by William Gies. His report, "Dental Education in the United States and Canada" outlined the history and current (at the time) status of dental education.

In the report, he outlines the history of dentistry in America. The key era is the mid 1800s. Medicine and dentistry were both growing. Dentists were primarily trained in an apprentice-style fashion. The problem was quacks, and in an effort to overcome them, formal education was needed. Paraphrasing the Gies Report (p.38, Ch 2) Horace Hayden gave lectures to medical students at the University of Maryland in 1837-38, but his effort "was not appreciated" by the faculty and he was not asked back. Gies states, "At that time every other American medical school, the first of which was organized in 1765, had been ignoring dentistry, although optional lectures on dental science and dental surgery had been given regularly, since about 1797, at the School of Medicine of Guy's Hospital, London, by Joseph Fox and other leading English practitioners."

So, attempts are made to establish formal dental education at the University of Maryland, but they are rejected. Gies writes, "the Medical Faculty expressing the opinion, that, 'the subject of dentistry was of little consequence and thus justified their unfavorable action.'" Attempts were also rejected in New York. And so an independent school for dental education, the Baltimore College of Dental Surgery was founded in 1840. As part of dental school, we had a course in dental history and learned about the first school in Baltimore and the Gies report. You can access the report from the American Dental Education Association: link