Optical Properties and Failure Load of Thin CAD/CAM Ceramic Veneers

This study aimed to compare optical properties and failure load of leucite (IPS Empress CAD LT) and lithium disilicate glass ceramic (IPS e.max CAD LT) materials in incisor veneers. Four groups of veneers were made on 36 bovine incisors with Cerec 3D milling unit (n=9/group): 0.5 and 0.3 mm thick leucite glass and 0.5 and 0.3 mm lithium disilicate glass veneers. The optical features were measured with CM-700d spectrophotometer using white and yellow try-in pastes. Differences were determined by means of ΔE value and luminance. The bovine teeth with veneers were mounted on acrylic resin blocks (Palapress, Heraeus Kulzer) and static loading test was conducted (LR30K plus, Lloyd Instruments). The color difference of veneers could be noticed with yellow and white cements when the material thickness increased from 0.3 to 0.5 mm (leucite ΔE yellow 4.4, white 6.0; lithiumdisilicate ΔE yellow 2.1, white 4.1). Both materials showed similar failure load with 0.5 mm veneers (leucite 1906 +/-319 N; lithiumdisilicate 2098 +/- 309 N). The failure load of 0.3 mm thick lithium dilisilicate veneers (2002 +/- 427 N) was comparable with the 0.5mm veneers. Ultrathin lithium disilicate glass ceramic veneers (0.3 mm) could be a potential option for clinical use.