There are three reasons why a restoration in a tooth could fail. First, the material could break or wear out. Second, the remaining tooth could break or start to decay. And third, some conditions such as gum disease could damage the support of a tooth or cause gum recession that would cause a cosmetic problem with an otherwise successful restoration. Based on this, considering that people bite, chew and swallow 24 hours a day, eat cold foods and drinks as low as 35 to 40 degrees (F) to hot beverages as warm as 150 degrees (F), there is nothing that could be considered “permanent”. That said, if the material selected is appropriate for the size of the cavity and the individual brushes and flosses daily, eats minimal sugar and uses prescription strength fluoride, most dental repairs will be very long-lasting.