The clinical repair of teeth using direct filling materials: engineering considerations

This paper reviews the way in which teeth damaged by caries may be repaired clinically. The mechanical effects of caries are described, as are the materials available to repair the damage caused by this disease. Studies are reported which have shown that caries reduces the compressive strength of the tooth to less than 50 per cent of its original value and that, by use of appropriate materials and placement techniques, this can be restored to some 80 per cent of this value. However, very few studies have been carried out which view tooth repair from an engineering perspective. Instead, emphasis is placed on determining clinical durability of repairs. This is related to repair strength but brings in other factors, such as the oral hygiene of the patient. Despite this complication, durability studies show that modern restorative materials perform well under clinical conditions, from which it may be concluded that the repair process allows a structure to be fabricated that is essentially sound from an engineering viewpoint, even if inferior to the original tooth structure provided by nature.