Why isn’t dentistry a medical specialty? Dental students could have essentially gone to medical school and then specialized in teeth (and oral medicine). Ophthalmologist specialize in eyes yet we don’t make them a whole new profession. Teeth are an organ like any other organ. For example in the UK oral and maxillofacial surgery is a medical specialty but in the United States it is classified as a dental specialty. This distinction seems arbitrary to me.
I am sure there is some historical reason that the professions never merged. Each one probably had its own culture and due to tradition and politics they just never felt the need to consolidate. Medicine is filled with arbitrary distinctions. The history and politics of medicine is fascinating. Medicine is a constant battle of different groups attempting to become recognized by the established medical culture. Look at the long hard fight that Osteopathic physicians had to endure in order to finally be recognized as equals. Maybe dentists didn’t care about that fight. They were content having their own culture. They wanted to keep their identity.