title: Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns.
abstract: OBJECTIVE
  All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident.
  
  
  METHODS
  Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also duplicated from the original prepared tooth for fracture testing. A universal testing machine was used to determine the fracture strength of the crowns.
  
  
  RESULTS
  THE MEAN FRACTURE STRENGTHS WERE AS FOLLOWS: 54.9 ± 15.6 N for the Lava CAD/CAM zirconia crowns and 87.0 ± 16.0 N for the Digident CAD/CAM zirconia crowns. The difference between the mean fracture strengths of the Lava and Digident crowns was statistically significant (P<.001). Lava CAD/CAM zirconia crowns showed a complete fracture of both the veneering porcelain and the core whereas the Digident CAD/CAM zirconia crowns showed fracture only of the veneering porcelain.
  
  
  CONCLUSIONS
  The fracture strengths of CAD/CAM zirconia crowns differ depending on the compatibility of the core material and the veneering porcelain.
authors.affiliation: Department of Dentistry, St. Catholic Hospital, Catholic University of Korea, Suwon, Republic of Korea.
authors.forename: Taek-Ka
authors.initials: TK
authors.lastname: Kwon
authors.forename: Hyun-Soon
authors.initials: HS
authors.lastname: Pak
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Yang
authors.forename: Jung-Suk
authors.initials: JS
authors.lastname: Han
authors.forename: Jai-Bong
authors.initials: JB
authors.lastname: Lee
authors.forename: Sung-Hun
authors.initials: SH
authors.lastname: Kim
authors.forename: In-Sung
authors.initials: IS
authors.lastname: Yeo
keywords: All-ceramic crown; Digident CAD/CAM; Fracture strength; Lava CAD/CAM; Zirconia