if I remember correctly Dentists had more cases of alzheimer than other groups of doctors. I heard it some time ago.
If is a prion, it should resist most sterilization of dental instruments by heat on autoclave. So is obvious IMAO that this could be a way to spread the disease from one patient to other, but I'm not an expert on clinic procedures and the protocols may have been updated. This is known, or at least suspected, since maybe a decade or so.
Don't remember, sorry. It was a lot of time ago. The articles should be listed in scientific indexes.
Dentists are a special group that worked a lot with mercury in the past, dunno if is related but it could be a combination of risk factors. We should ask a chemist.
In any case today the facts can be very different.