Effect of monolithic zirconia thickness on light transmission and microhardness of resin cement
Author(s): Zena A. Ahmad*
Abstract
Aim of the study: the aim of this study was to investigate the influence of different thicknesses for two types of monolithic zirconia on light intensity and microhardness of underlying resin cement. Material and method: 48 specimens of two types of monolithic zirconia which are Copra Supreme (CSP) and Copra Smile (CSM) were fabricated using CAD CAM machine with three different thicknesses (0.5mm,1mm, 1.5mm). Intensity of light transmitted through the zirconia was calculated using a radiometer. Discs of dual cure resin cement prepared and light activated through the zirconia specimens, all samples subjected to Vickers microhardness test. Data were analyzed using ANOVA, Tukey HSD, Dunnett’s tests, and t-test at (α = 0.05). Results: The thickness and type of monolithic zirconia had a significant impact on light transmission and microhardness (p-value <0.05). Light intensity and microhardness were significantly decreased for both zirconia types. There was significant difference among different thicknesses of each zirconia type. CSP zirconia showed significant fewer values than CSM zirconia in all thicknesses. Conclusion: The increase in the monolithic zirconia thickness might reduce the intensity of transmitted light and microhardness of resin cement. CSM zirconia had less effect on light intensity and microhardness than CSP zirconia.