Lots of highly specialized fields fall under medicine. Ophthalmology does, for instance. So how did dentistry come to exist as a separate entity? Is this phenomenon worldwide?
Dentist’s training comes from dental school, where the teeth, and surrounding relevant structures are studied in great depth. An opthalmologist goes to medical school, where the training is in all of medicine, and is a medical doctor first, before going on to specifically study the eyes. His medical license will generally read that s/he is licensed to practice both medicine and surgery. An optometrist on the other hand goes to optometry school, and is not a medical doctor.
That’s one difference. It’s late. I’m sure other dopers can delineate more differences.
Qadgop, MD
so very, very tired
The fields of medicine and surgery developed very differently. Medicine was a higher status profession (‘magical cures’ etc.) whereas surgery was more like carpentry. Although there was some early crossover with some medics resorting to surgery, most surgery was done by skilful artisans rather than by ‘medicine men’. In the last three centuries, surgery has come back into the fold.
The two hangovers are dentistry and chiropody which in many countries do not require a medical degree.
As a hijack- why do you need a medical degree to treat mental ‘illness’?
The limits of medicine are strange and wonderful! Medicine has a history of gathering into it areas that were once rejected by it- its boundaries are flexible.
The flippant answer of course is that dentistry is a field set up to cope with disappointed med school failures. 
Because many “mental” illnesses have physical causes. Perhaps most of them do, and we just haven’t found all the reasons yet. Depression, manic-depression (bipolar disease), and schizophrenia all come to my mind when I think of mental illnesses that can be treated with appropriate medications.
I guess I need to clarify the OP.
What I’m interested in is why, historically, are dentistry and allopathic medicine (ie. surgery, medicine, pediatrics, ob/gyn, psychiatry) unlinked?
My opinion is that there is no fundamental difference between body parts cared for by dentists and those cared for by MDs. Oral health is affected by systemic disease as well as by local pathological processes, just like any other body part. To be an effective dentist one must study and understand many concepts that are central to allopathic medicine: pathology, pathophysiology, anatomy, infectious disease, pharmacology, and patient compliance to name a few.
One might say that taking care of the teeth and gums requires a high level of specific training, and perhaps this explains the need for the separate status of dentistry. But, as I pointed out in the OP, such specialization exists in allopathic medicine. Ophthalmologists, for example, are MDs that take care of the eyes, just the eyes.
Since I’m at a loss to discern a biological reason for the split between the fields of medicine and dentistry, I’m of the mind that they are separate secondary to the vicissitudes of history.
Anyone know 'bout 'dem vicissitudes?
And many do not have physical causes, and those that have physical correlates are only marginally tied to the physical in comparison to ‘real’ illnesss.
Additionally, drugs can affect other non-medical problems- borderline criminality, lack of will, willfulness etc., yet we don’t claim these as illnesses. Psychiatry IMHO made a bid for those parts of behaviour that could be medicalized, this bid was accepted by society, but the case for its scientific validity is yet to be properly met.
This is probably another thread, but I brought it up to reinforce my assertion that the purview of medicine is largely socially, not scientifically, defined.
Briefly, I guess it’s because it’s not thought necessary to go to medical school to be a dentist. The same applies to podiatrists (who do limited surgery and prescribing) and optometrists (who do limited prescribing). Perhaps Opthalmologists are expected to be physicians first as the eyes are a bit trickier to do surgery on, and more of a loss if vision is reduced. I’m sure a lot of the reasoning for these separations is more historical and societal than scientific, but I guess that’s just the way it is for present.
As for how dentistry got that way, I guess early on, dentistry consisted of yanking a bad tooth, and a few surrounding ones for good measure. Not too complicated. Meanwhile, the medicine types were fiddling around with urine and faeces, and composing elaborate theories about how the body works involving humors, the brain being involved in cooling blood, etc. It may have been wildly inaccurate, but at least it was scientific. As opposed to the blacksmith down the street who’d pull your tooth if it was bothering you. Very useful, very practical, definitely a go-to guy if you had a problem, but certainly not up to university standards!
All this is just a WAG on my part.
choosybeggar: “Since I’m at a loss to discern a biological reason for the split between the fields of medicine and dentistry, I’m of the mind that they are separate secondary to the vicissitudes of history.”
You’re right.
MDs are, as Qad writes, trained “in all of medicine” which includes the entire human body, its structure, growth, development, normal function and pathology. But they don’t normally learn how to manage common dental problems which has to make them feel at least a little inadequate. After all, a psychiatrist or ophthalmologist knows how to deliver babies and examine the ear drum, but neither can tell when a root canal is needed.
This brings up the question of whether it still makes sense for ophthalmologists and psychiatrists to be fully trained in medicine. Dentists do a good job on the teeth without studying the entire human body in depth or learning to deliver babies or examine ear drums.
Lynn Bodoni:
Sorry, but I must chime in with Pjen. Depression, manic-depression(bipolar) and schizophrenia would at best fall into the category of diseases that “may have physical causes and we just haven’t found all the reasons yet”.
Which is to say “after 100+ years of diligent searching”.
Once upon a time, when a certain pattern of dementia was found to be caused by latter-stage syphilis, and another ‘disturbing behavioral pattern’ came to be understood as epilepsy, it was conjectured that all the mental/emotional/cognitive problems that plague humanity actually had a physical cause. This was seen as a far more rational understanding than the rather pre-scientific beliefs that predated it.
But the pattern is that if a given mental ailment is traced to an infectious agent such as syphilis or a structural anomaly such as epilepsy, it is no longer classified as a “mental illlness”, so what remains so classified is, that which we don’t have a causal explanation. Or one that the rest of the medical community is willing to buy, at least.
To answer the OH (original hijack 
), the reason psychiatrists have to be doctors is rooted in asylum history: people like Kraepelin and Bleuler wanted someone who represented propriety and authority to head the asylums they advocated, and a medical doctor possessed substantial amounts of that (at that time), so they decided possession of a medical degree was a job requirement.
On my web site are substantial excerpts from David Hill’s book THE POLITICS OF SCHIZOPHRENIA, which analyze the shakiness of scientific basis for claims that a disease condition, “schizophrenia”, does in fact exist.
Standard disclaimer: In case you or anyone you know finds benefit in seeking out psychiatric treatment, please understand that I do not mean to imply that such treatment is never of benefit. The fact that they don’t really know what they are doing doesn’t mean that someone else necessarily does, or that doing nothing is always better than trying something.
Oops, I referenced a larger chunk of readings than I needed to. Unless you are up to a lengthy reading assignment, use this [URL-“http://members.aol.com/ahunter3/psych_inmates_libfront/vol_1/Hill/Hill_InadeqData.html”]shorter set of excerpts instead.
Bloody hell. shorter set URL done correctly.
Well, you don’t. Psychologists (esp. those with Ph.D.s) can treat mental illness, and they can also prescribe medicines.
I don’t know about all of the country, or world, but here in Texas if a psychologist feels a prescription only drug is needed to facilitate treatment, the patient is referred to a psychiatrist (M.D.) who actually writes the 'scrip.
Not prescribe in the US they can’t. Many are certainly fighting for the privilege to prescribe, but only a few, who hold dual status as psychologists andnurse practitioners or physician assistants, can prescribe, and then only under the supervision of a physician (MD or DO).
Admittedly it may be different elsewhere.