Objective:The purposes of this study were to determine the spectral transmittance of GI-Òglass/alumina composites and to explore the effects of different specimen thickness and firing arts of glass infiltration on the transmittance. Datawere comparedwith those of Vita In-Ceram Alumina materials.Methods:Plate-shaped specimens 1215 mm in diameter, with 3 thickness (015, 110, 115 mm), 6 colorgroups forGI-Òand 4 colorgroups forVita In-CeramAlumina were fabricated. Specimens of colorAL2 for In- Ceram and IG2 forGI-Òwere selected in the study of relationship between different infiltration arts and transmittance. Five infil- tration time duration and three temperatureswere studied. A spectrophotometerwith standard A light source paralleled lightbeam 5 mm in diameter and spectra range 380~780 nmwas employed to measure the spectral transmittance.Results:The range of spec- tral transmittance were 217%~415% for GI-Òand 214%~512% for Vita In-Ceram Alumina. Transmittance decreased with specimen thickness, buttheywere not linearly related. Transmittance ofGI-Òtended to increase and thatofVita In-CeramAlumi- na decreased as the infiltration temperature elevated. The transmittance increased with infiltration time less than 4 hours and re- ducedwith prolonged time over 6 hours for both materials.Conclusion:GI-Òglass/alumina composite has comparatively lower translucency. Influences of factors as color, thickness and infiltration arts on translucency of restorations should be considered in the clinical selection of the all-ceramic materials.
