Assessment of Capability of Lithium Disilicate Glass Ceramics to Reproduce the A2 Shade and to Mask A4 Substrates
Keywords:Ceramics, discoloration, shade
Aim: Capability of lithium disilicate glass ceramics to reproduce the A2 shade and to mask A4 substrates.
Materials and Method: 32 lithium disilicate ceramic specimens were classified materials into 8 groups
of 4 each. Group I- III high translucency (HT) monolayer discs, group IV- VI had low translucency (LT)
monolayer discs, group VII- VIII had medium translucency (MO) bilayer discs. A2 shade tab shade guide
(VITA classical A1-D4) was used for CIE L*a*b* measurements of control. Color differences using thresholds
was as follows: for imperceptible (?E < 1.0), perceptible (1.0 < ?E < 3.3), and clinically unacceptable (?E
> 3.3) differences.
Results: ?E in group IV exhibited highest (9.92±0.21) and group III lowest (8.08± 0.25) value. When the
complex was compared to the A4 substrate, significant difference among all groups (p < 0.05) was found.
?E values when the complex was compared to the A2 shade tab, group III exhibited highest (4.82±0.16)
and group V lowest (0.72±0.06) value. In groups I specimens had acceptable differences, group II had
perceptible differences, group III had perceptible differences, group IV had acceptable differences, group V
had imperceptible differences, group VI and VII had acceptable differences and group VIII had imperceptible
Conclusion: Authors suggested to use LT ceramics with less thickness in the range of 0.5 mm- 0.7 mm to