Biofilms are an evolutionary advantage for the bacteria, not the host. Biofilms make the colony much, much harder to kill. How advantageous can it be to the host anyways, if 4 out of 5 dentists recommends obliterating it 2-3x a day?
It’s like trying to stop drug use by busting drug dealers. As long as the niche exists a city can’t stop and say we caught all the bad guys problem is solved.
We might call it the same species, but the relevant chararistic changed is detrimental to a [human] host but beneficial to the [bacteria] parasite.
We might call it the same species, but the relevant chararistic changed is detrimental to a [city] host but beneficial to the [drug dealer] parasite.
Consider if you removed all the wings on misquotes in a city. That would be useful on day 1, but not going to do anything a year from now. It’s the same species, but missing a very useful trait means it’s getting outcompeted.
That's not an accurate analogy for biofilms. Even if it was, I noted below that the mechanical action of brushing your teeth annihilates any biofilm (i.e. plaque) that has built up. That being the case, how do you explain the fact that people who brush their teeth are not suffering from infection from advantageous disease?
If you wipe out your gut flora, there are health serious implications. All evidence seems to point to the opposite case in your mouth.
Anyway brushing your teeth doesn't sterilize your mouth or even disrupt your mouth flora that much.
But brushing and flossing does do many things. It helps your spit/toothpaste to remineralize your teeth repairing microscopic damage, removes leftover buts of food, and generally makes your mouth noticeably less hospitable to bacteria alongside reducing biofilms.
As soon as you stop bushing things start getting worse, but that's why it's a daily activity.
I said it would be detrimental to the bacteria’s health not the persons.
Not brushing would be bad for a persons health, and this would still be true after treatment with modified bacteria.