Quantification of the amount of blue light passing through monolithic zirconia with respect to thickness and polymerization conditions
Section snippets
Material and Methods
Four hundred eighty specimens were fabricated. The analyzed ceramics, their manufacturer, lot number, and chemical composition are presented in Table 1. Zirconia (12 mm wide × 12 mm long) and glass ceramic disks (10 mm wide × 10 mm long) were cut with a high performance cut-off machine (Secutom-50; Struers) in the following thicknesses: .5, 1, 1.5, 2, 2.5, and 3 mm. Zirconia specimens were sintered (LHT 02/16; Nabertherm GmbH) according to the manufacturers’ instructions (Table 2). A glass
Results
Ceramic thickness exerted the highest influence on the transmitted irradiance (P<.001, partial eta squared [ηP²]=.998), closely followed by polymerizing mode (P<.001, ηP²=.993) and ceramic (P<.001, ηP²=.873). The interaction effect of the binary and ternary combinations of the 3 independent parameters (ceramic, ceramic thickness, and polymerizing mode) was significant for all combinations (P<.001), while the effect strength in descending order was: ceramic thickness combined with polymerizing
Discussion
All null hypotheses were rejected. The translucency of zirconia is determined by a complex combination of different parameters, including residual porosity,7 grain size,8 primary particle size,9 additives such as alumina,12 and sintering.9 Confirming the literature data,5 the analyzed zirconia were all less translucent than the glass ceramic used as positive control. The comparison among the zirconia materials proved that the so-called translucent zirconia and traditional zirconia differed less
Conclusions
Within the limitations of this study, the following conclusions can be drawn:
- 1.
In less advantageous conditions (material thickness of 3 mm, standard power mode), the amount of light passing through specimens ranged from 48.4 mW/cm² to 102.6 mW/cm² for the materials in the following order: Prettau, InCoris TZI, Ceramill Zolid, DD Bio ZW, ZENOStar, VITA Mark II, GC ZR Disc CIP, and Ceramill ZI.
- 2.
The decrease in transmitted irradiance with increased specimen thickness in all materials is well
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