Good teeth are, I reckon, mostly about having the right parents.
I live on a diet that includes large quantities of chocolate and orange juice, brush them once a day, and until the other week hadn't seen a dentist for 10 years. Other than the disintegrating filling (one of three, two of which were necessitated by mechanical damage
[1] as a kid) that forced the issue, my teeth were declared to be in excellent condition, and the hygienist suggested I not bother coming back any time soon.
Barakta's family, OTOH, are plagued by crap teeth, in spite of religious oral hygiene, eschewing proper food with calories in, and spending unholy amounts of time and money on dentists.
[1] I was of the generation whose dentists thought it was a good idea to pre-emptively coat undamaged molars with some kind of durable sealant. This may have worked if the extra thickness hadn't interfered with the bite action, and broken some of the tooth away when the inevitable happened...