In the 1970s it was all the rage that there were patents on 200 mpg carburetors, but the oil companies bought the patents in order to suppress those carburetors.

I asked my dad about it (career Air Force). He laughed and said that gasoline consumption was a major logistics problem for the military. If there were 100 mpg carburetors, the military was going to use them, and to hell with any patent blockade.

(Note all the problems the Germans had in WW2 when the US severely damaged their oil refineries.)

Do you mind picking to some of these? I did a quick Google patents search but didn't find anything.

Colgate Palmolive 1973: https://patents.google.com/patent/US3931398A/en

Merck & Co 1979: https://patents.google.com/patent/US4287173A/en

Lion Corp 1983: https://patents.google.com/patent/US4693888A/en

In all likelihood these just didn't work, but the commercial interest to not have caries immunization is just too juicy not to theorize!

Interesting, all of the ones you cite are older than 20 years, so the patents should have long expired and should be free for anyone to bring to market?