الفهرس 
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Abstract
Degree of conversion of resin cements used in bonding lithium silicate ceramic restorations has a great impact on long-term success of ceramic restorations.
This study shows the effect of ceramic type, mode of light curing, and shade of resin cement on the degree of conversion of the light cured resin cement.
Materials and methods: 84 ceramic samples were prepared from three types of ceramics: IPS E.max CAD, Celtra Duo CAD and Vita Suprinity CAD (each group =28 samples). The samples were further divided into two subgroups according to the light curing mode whether continuous or pulsating mode (n=14). They were then divided according to resin cement shades whether A2 or translucent shade (n=7). Teflon mold was fabricated with specific dimensions, where the ceramic disc was placed followed by light cured resin cement (Bisco choice 2 veneer) and a glass slab with finger pressure applied. Curing with Bluephase Ascent ® PX LED light cure unit for 20 seconds took place, where the tip was in direct contact with the ceramic sample. Cement film was then separated from the ceramic disk and subjected to analysis by Fourier Transform Infrared Spectroscope. Uncured cement samples were also subjected to analysis. Both values were used in the equation below to obtain the degree of conversion.
For composites having internal standard, the percentage of unreacted aliphatic C=C bonds remaining throughout the polymerization reaction is obtained by the equation:
where Abs can be the height or the area of absorption band.
DC is determined by subtracting the residual percentage of aliphatic C=C from 100% (DC%=100-(%C=C)
Results showed higher degrees of conversion in with the translucent resin shade than the A2 shade. There was no statistical significance difference in degree of conversion between the three ceramic types (IPS Emax, Celtra, and Vita Suprinity). There was higher DC% in the continuous light curing mode that the pulsating mode.