This study evaluated the marginal fit of CAD-CAM Zirconia cores with different
proximal height. Thirty Zirconia cores and ten metal ceramics crowns were used to evaluate the
marginal gap. The marginal fit was determined to be perpendicular to the tooth axis between the
most apical point on the coping margin (core) and the reference marks on the mesial, distal, labial,
and palatal surfaces of the die at several key stages of crown fabrication; before porcelain built-up,
after body porcelain built-up, and after glazing. Additionally, an opaque stage for the metal ceramic
copings was compared as well. Each measurement was carried out with a microscope. The means of
gaps among the groups were 58±27 -m, 69±23 -m, 89±29 -m and 80±28 -m, groups I, II, III and
IV, respectively. In relation to the proximal and labiopalatal surfaces there were no statistical
difference among the groups, except group I. No significant differences were observed in firing
stages of all groups. The findings of this study showed that the mean marginal gap of Zirconia
cores with different proximal heights fell well within the acceptable clinical ranges.
Effect of Incisal Porcelain Veneering Thickness on the Fracture Resistance of CAD/CAM Zirconia All-Ceramic Anterior Crowns