According to nutricionist Robert von Sarbacher (video 53:28 min - 54:45 min) eating 4 days of root vegetables will make your teeth throb with power as if arteries were flowing through your teeth.
He calls them "bone veins" and there are hundreds of them. They supply nutrients from the jaw to the teeth.
If the teeth become rotten the nutrients start to flow in reverse; from the teeth to the jaw and the teeth become infected.
I've tried eating carrots just for one day and it's true. Your jaw starts to hurt :)
I think this should be taught to kids in school. Chew carrots for strong teeth.
Teeth are like muscles. If you don't use them they atrophy.
Oil pulling
Robert also recommends regular oil pulling with sunflower oil. Oil pulling helps to pull poisons out of the gums and teeth.
Oil pulling is the act of swishing oil inside your mouth for 21 minutes and then spitting it out (in the toilet bowl). He recommends doing it 7x3 min. It's done for 3 weeks.
My advice for healthy strong teeth:
Oil pulling
Chew carrots or other root vegetables (turnips, kohlrabi, celery root, horseradish) regulary
Don't eat too much sugar
Regular check ups with the dentist