[Spectral transmittance of GI-II glass/alumina composite].
OBJECTIVE
The purposes of this study were to determine the spectral transmittance of GI-II glass/alumina composites and to explore the effects of different specimen thickness and fining arts of glass infiltration on the transmittance. Data were compared with those of Vita In-Ceram Alumina materials.


METHODS
Plate-shaped specimens 12.5 mm in diameter, with 3 thickness (0.5, 1.0, 1.5 mm), 6 color groups for GI-II and 4 color groups for Vita In-Ceram Alumina were fabricated. Specimens of color AL2 for In-Ceram and IG2 for GI-II were selected in the study of relationship between different infiltration arts and transmittance. Five infiltration time duration and three temperatures were studied. A spectrophotometer with standard A light source paralleled light beam 5 mm in diameter and spectra range 380-780 nm was employed to measure the spectral transmittance.


RESULTS
The range of spectral transmittance were 2.7%-4.5% for GI-II and 2.4%-5.2% for Vita In-Ceram Alumina. Transmittance decreased with specimen thickness, but they were not linearly related. Transmittance of GI-II tended to increase and that of Vita In-Ceram Alumina decreased as the infiltration temperature elevated. The transmittance increased with infiltration time less than 4 hours and reduced with prolonged time over 6 hours for both materials.


CONCLUSIONS
GI-II glass/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.
Meng
Yukun
Y
West China College of Stomatology, Sichuan University.
Chao
Yonglie
Y
Liao
Yunmao
Y
D000537:Aluminum Oxide / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D003764:Dental Materials; D003776:Dental Porcelain / Q000737:chemistry; D005898:Glass / Q000737:chemistry*; D008027:Light; D013053:Spectrophotometry; D013696:Temperature; D013718:Tensile Strength; D044366:Transition Temperature
D003764:Dental Materials; D003776:Dental Porcelain; D000537:Aluminum Oxide