There is a mini spectrometer that you can aim at things
find out the chemicals in them. I think putting this in a
phone has been published.
What if a laser pen like thing could be aimed at the
near toothbrushing time to do spectroscopy? Could it
like high cholesterol or trace
If it is too much $ perhaps they could simply wave it at
your mouth when you go to the dentist.
I suppose one improved version of this could be part of
electric toothbrush with optical fiber bristles that got
near the tongue.
"laser tongue diagnostic" is not at the
first page of a search engine.