The application of thermoelastic analysis to study stresses in human teeth

The aims of this investigation were to use a full-field thermoelastic technique to study the stress distribution on human teeth subjected to dynamic loads and derive a value for the thermoelastic constant for human enamel. Surface stresses were observed on extracted intact human molar teeth subjected to a load of 200 N cycled at 20 Hz. Measurements were repeated for the same teeth following mesio-occluso-distal cavity preparation and restoration with amalgam and adhesively bonded composite restorations. A value for the thermoelastic constant for human enamel (Km) of 2.25 X 10(-12)m2/N was calculated from physical coefficients in the literature. Unprepared specimens exhibited a comparable magnitude and distribution of stresses to those seen when teeth were restored with adhesively bonded composite restorations. Higher stresses were observed on prepared teeth and there was little change following restoration with amalgam. It can be concluded that a full-field thermoelastic stress analysis technique can be successfully applied to study teeth subjected to axial dynamic loads in vitro and that the resultant stresses are greater in prepared teeth than those restored with bonded composite materials.