LOSS OF LIGHT INTENSITY OF DENTAL PHOTOPOLYMERIZERS IN GLASS IONOMER CEMENTS

Relevance. For hybrid dualand tri-cure glass ionomer cements, it is necessary to determine certain irradiation conditions. Objective. To determine the loss of light intensity of photopolymerizers with different characteristics in glass ionomer cements. Materials and Methods. The loss of light intensity from a halogen photopolymerizer and two LED photopolymerizers was studied in 60 samples of dual-cure hybrid glass ionomer cement in shades A1 and A4 (Groups 1 and 2) and 60 samples of tri-cure glass ionomer cement in the same shades (Groups 3 and 4). Ten samples of 4 mm thickness from each group were irradiated for curing, and the loss of light intensity was measured. The samples were then polished to 3 mm and 2 mm thicknesses, and the losses were reevaluated. Results. The greatest losses in light intensity were observed with the halogen photopolymerizer, which had the lowest initial output (812.5±9.7 mW/cm²). The maximum light intensity loss for this photopolymerizer was recorded in 4 mm-thick samples of both cements in the darkest shade, A4, amounting to 94.7±2.2% and 92.1±2.4%, respectively. Higher initial light intensity from LED photopolymerizers resulted in systematically lower losses. The minimal light intensity loss was recorded with the LED photopolymerizer with the highest initial output (1434.8±7.9 mW/cm²) in 2 mm-thick samples of both cements in the lightest shade, A1, at 53.9±1.9% and 51.3±1.5%. The most significant reduction in light intensity was observed between 3 mm and 4 mm sample thicknesses compared to 2 mm and 3 mm, regardless of material, shade, or initial light intensity. Conclusions. When using hybrid dualand tri-cure glass ionomer cements, it is necessary to consider not only the layer thickness but also the material shades and the initial light intensity parameters.