Method: Veneer preparations were made in 36 bovine incisors (width 12.5 +/- 0.5mm and thickness 2.5 +/- 0.3mm) The veneers are made with Cerec 3D milling unit and divided into four groups (n=9/group): Empress CAD thickness 0.5 mm and 0.3 mm and e.max CAD thickness 0.5 mm and 0.3 mm. The optical features are measured with CM-700d spectrophotometer using white and yellow try-in pastes. Differences among the materials were determined by the means of DE value and luminance.
Result: Some differences in DE values were found among the substrates, but they did not exceed the just-noticeable-difference threshold. However, veneers of 0.3 mm thickness had higher luminance than the 0.5 mm veneers: difference with white try in paste 5.9 for Empress CAD LT and 3.2 for e.max CAD LT (p<0.01). No difference between the two materials was found.
Conclusion: Thickness is more important factor for the optical properties of CAD/CAM veneers than the type of milling material.