Reliability of reduced-thickness and thinly veneered lithium disilicate crowns

The present investigation hypothesized that the reliability of reduced-thickness monolithic lithium disilicate crowns is high relative to that of veneered zirconia (y-tzp) and comparable with that of metal ceramic (mcr) systems. cad/cam first mandibular molar full-crown preparations were produced with uniform thicknesses of either 1.0-mm or 2.0-mm occlusal and axial reduction,then replicated in composite for standard crown dies. monolithic 1.0-mm (mon) and 2.0-mm cad/cam lithium disilicate crowns,the latter with a buccal thin veneer (btv) of 0.5 mm,were fabricated and then sliding-contact-fatigued (step-stress method) until failure or suspension (n = 18/group). crack evolution was followed,and fractography of post mortem specimens was performed and compared with that of clinical specimens. use level probability weibull calculation (use load = 1,200 n) showed interval overlaps between mon and btv. there was no significant difference between the weibull characteristic failure loads of mon and btv (1,535 n [90% ci 1,354-1,740] and 1,609 n [90% ci 1,512-1,712],respectively),which were significantly higher than that of y-tzp (370 n [90% ci 322-427]) and comparable with that of mcr (1,304 n [90% ci 1,203-1,414]),validating the study hypothesis. © 2012 international & american associations for dental research.