Unlike crowned teeth, intact teeth are extremely unlikely to become infected or die. Teeth with very large fillings are also unlikely to die or become infected . I have had several endodontists tell me that crowns are the main reason teeth die and become absessed.Crowns are never beneficial.As far as the immune system taking care of the bacteria buildup around crowns, if this were effective then crowned teeth would be no more likely to die ,become absessed and cause periodontal problems than teeth with fillings. Dentists do crowns to make money.Dentists become dentists because they are 20 I.Q. points short of medical school acceptance . Pick up Frank Jerome's book.
Further evidence that crowns are neither beneficial or neccessary is the fact that insurance companies rarely cover them.