Influence of glass-based dental ceramic type and thickness with identical shade on the light transmittance and the degree of conversion of resin cement

摘要

The purpose of this study was to assess the influence of the types and thicknesses of glass ceramic plates on light transmittanceand compare the degrees of conversion （DC） of resin cement under the ceramic materials. Three ceramic plates with thicknesses of0.5, 1.0, 2.0, and 4.0 mm were fabricated from each of fve commercial ceramic blocks in shade A2; high-translucency and low-translucency IPS Empress CAD （Emp_HT and Emp_LT）; high-translucency and low-translucency IPS e.max CAD （Emx_HT andEmx_LT）; and Vita Mark II （Vita）. The translucency parameter was obtained using a colorimeter. The light transmittance rate wasmeasured using a photodetector attached to an optical power meter. The DC of a resin cement （Variolink N） underneath theceramic plates was examined by Fourier transform infrared spectroscopy. The translucency parameter, light transmittance rate, andDC showed significant differences by ceramic type and thickness （P〈 0.05）. The Emp_HT specimens showed the highest lighttransmission and DCs, and the Emx_LT showed the least light transmission and the lowest DCs. The high-translucency Empressshowed significantly higher DCs than the low-translucency types （P 〈 0.05）, but there was no significant difference in e.max （P 〉0.05）. Both type and thickness of the glass ceramics signifcantly influenced the light transmittance and DC of the light-cured resincement beneath the ceramic of the same shade.