Teeth are unusual among body parts in that most of the damage is preventable and almost none of it repairs itself. Enamel does not grow back. That single fact is why daily habits count for more than anything a dentist can do afterwards, and why dentistry is far more a matter of maintenance than of rescue.
This section covers cleaning thoroughly rather than vigorously — not the same thing, and one of the two wears enamel away; what fluoride does and does not do; what the common treatments actually involve, from a filling to a crown to a root canal; and how to make sense of a dental bill.
Also worth reading: what food does to teeth.