INFLUENCE OF PASTE TEMPERATURE AT CURING ON CONVERSION RATE AND BENDING STRENGTH OF LIGHT-CURED DENTAL COMPOSITES

Pastes of three dental composites were tempered to 20 degrees C, 37 de grees C and 60 degrees C. Test specimens (22 x 2 x 2 mm) were cured by light and stored in deionized water. Three-point bending strength was measured after 1 h and after 24 h. Degree of conversion on the surfac e exposed to the curing light and the opposite surfaces at the bottom of the mould was analysed by Fourier transform infrared (FTIR) after 1 h. After 1 h, specimens produced using the pastes cured at 60 degrees C showed significantly higher bending strength than the specimens pro duced using pastes cured at 20 degrees C and 37 degrees C. However, af ter 24 h the composites pretempered at the lower temperatures had deve loped the same level of bending strength as the composites cured at 60 degrees C. An increase in the degree of conversion with increased pas te temperature was found in all materials after 1 h.