Most dentists spend three years in school, where 2.25 of them are spend just learning the hand skills of dentistry. By the end of it, they are highly motivated to not want to advance dental science because it could put them out of a job.
If someone developed a drug that would remove cavities, or a device that made it so you didn't have to brush every day, these would be huge quality of life improvements for people, but the people who are most expert at discovering such things are the ones most motivated to keep the status quo.
I say this as someone who has multiple family members involved in dentistry. Every time I even mention a new possible treatment, their immediate response is "hmmm I'm not sure that's a good idea that's not how we usually do things". It's something that their training has engrained in them.