The aim of this research was to
evaluate the degree of monomer conversion of different resin cement
shades when photocured under different feldspathic ceramic shades. The
photocuring time was also evaluated as well as the translucency of each
Three VITA VM7 ceramic shades (Base
Dentin 0M1, Base Dentin 2M2 and Base Dentin 5M3) were used to determine
the translucency percentage. A spectrophotometer MiniScan was used to
measure the opacity percentage of each specimen (2-mm-thick) and then
the translucency was calculated. To measure the degree of conversion
(DC), the resin cement (Variolink II; A3 Yellow and transparent)
specimens (thickness: 100μm) were photocured under a ceramic block (2-mm-thick) for 20 or 40s. Specimens photocured without the ceramic block were used as control. Sixteen groups (n=3) were evaluated. Micro-ATR/FTIR spectrometry was used to evaluate the extent of polymerization of all specimens after 24h. The %DC was calculated of experimentally polymerized versus maximally polymerized composite.
translucency percentages of 0M1, 2M2 and 5M3 ceramics were 12.41
(1.02)%, 5.75 (1.91)% and 1.07 (0.03)%, respectively. The %DC of both
resin cement shades cured under ceramic 5M3 was significantly lower than
the other groups (p<0.05). The %DC of 0M1 groups exhibited no significant difference from 2M2 groups (p>0.05), with the exception of the transparent cement photocured for 40s.
Photocuring under 2mm ceramic showed that the increase in chroma saturation significantly decreased Variolink II resin cement %DC (100-μm-thick).