[Dimensional behavior of six light-cured veneer acrylics]

During irradiation light-cured veneer acrylics underwent shrinking by 2.2 to 4.8%. In operation, the temperature in the irradiation chambers of the light units increased up to a maximum of 87 degrees C. The coefficients of thermal expansion a20/100 of the acrylics ranged between 49.2 and 72.2 x 10(-6)/K. Dimensional changes of the acrylics due to high polymerization contraction and/or due to a different thermal behavior than that of the metal framework may produce stresses in the bond system and possibly promote a deterioration of metal retention.