Effect of Occlusal and Margin Design on the Fracture Load of Zirconia-Lithium Disilicate Bi-layered Posterior Crowns: An in Vitro Study
- Author:
Sung-Hoon KIM
1
;
Kyung-Ho KO
;
Chan-Jin PARK
;
Lee-Ra CHO
;
Yoon-Hyuk HUH
Author Information
- Publication Type:ORIGINAL ARTICLE
- From:Journal of Korean Dental Science 2025;18(1):1-11
- CountryRepublic of Korea
- Language:English
-
Abstract:
Purpose:The opacity of zirconia sometimes requires a veneering material; thus lithium disilicate, a veneer material with excellent strength, can be used. This study investigated the fracture resistance of zirconia–lithium disilicate (Zr-LS2) bi-layered crowns according to the design of the substructure.
Materials and Methods:Five groups of posterior Zr-LS2 restorations (Zirtooth and Amber LiSi-POZ) were fabricated with different zirconia substructure coverage (control group, groups half occlusal zirconia coverage; 1/2OZ, and three-quarter occlusal zirconia coverage; 3/4OZ) and margin designs (control group, groups collar margin; C-M, and collarless margin; Cl-M). All restorations were cemented with self-adhesive resin cement followed by 24-h water storage and thermocycling (10,000 cycles, 5°C and 55°C). The fracture load was measured, and failure mode analysis, fractography, and elemental analysis were performed. The one-way analysis of variance and Fisher’s exact test were performed for statistical analyses (α=.05).
Results:A significant difference was found in the fracture load of Zr-LS2 restorations according to the zirconia coverage of the occlusal area and margin design (P<.05). Group 3/4OZ was significantly larger than the control group C and 1/2OZ (P<.05). The C-M group had greater fracture loads based on margin design than the control group C and Cl-M (P<.05).
Conclusion:The fracture resistance of posterior Zr-LS2 restorations increased with the zirconia coverage, occlusal thickness, and collar margin.
