Gaoqi Wang1, Song Zhang2, Cuirong Bian3, Hui Kong4. 1. Doctoral student, School of Mechanical Engineering, Shandong University, Key Laboratory of High Efficiency and Clean Mechanical Manufacture (Ministry of Education), Jinan, P.R. China. 2. Professor, School of Mechanical Engineering, Shandong University, Key Laboratory of High Efficiency and Clean Mechanical Manufacture (Ministry of Education), Jinan, P.R. China. Electronic address: zhangsong@sdu.edu.cn. 3. Chief Physician, Department of Prosthodontics, Qilu Hospital of Shandong University, Jinan, P.R. China. 4. Resident, Department of Prosthodontics, Qilu Hospital of Shandong University, Jinan, P.R. China.
Abstract
STATEMENT OF PROBLEM: Chipping of veneering porcelain and delamination of a zirconia-veneer interface are 2 common clinical failure modes for zirconia-based restorations and may be partially due to weak interface bonding. The effect of liner on the bond strength of the interface has not been clearly identified. PURPOSE: The purpose of the research was to evaluate the interface toughness between the zirconia core and veneering porcelain by means of a fracture mechanics test and to assess the effect of liner on the bond strength of the interface. MATERIAL AND METHODS: Thirty bilayered beam-shape specimens were prepared and divided into 2 groups according to liner application. The specimens in each group were subdivided into 3 subgroups in accordance with 3 different veneer thicknesses. A fracture mechanics test was used on each specimen, and the energy release rate, G, and phase angle, ψ, were calculated according to the experimental results. A video microscope was used to monitor the crack propagation, and a scanning electron microscope was used to identify the fracture mode after testing. Two-way ANOVA and the Tukey honestly significant difference test were performed to analyze the experimental data (α=.05) . RESULTS: At each phase angle, the interfaces without a liner had higher mean G values than the interfaces with a liner. Both of the interfaces showed mixed failure mode with thin layers of a veneer or a liner that remained on the zirconia surfaces. CONCLUSIONS: Liner application before veneering reduced the interface toughness between zirconia and veneer.
STATEMENT OF PROBLEM: Chipping of veneering porcelain and delamination of a zirconia-veneer interface are 2 common clinical failure modes for zirconia-based restorations and may be partially due to weak interface bonding. The effect of liner on the bond strength of the interface has not been clearly identified. PURPOSE: The purpose of the research was to evaluate the interface toughness between the zirconia core and veneering porcelain by means of a fracture mechanics test and to assess the effect of liner on the bond strength of the interface. MATERIAL AND METHODS: Thirty bilayered beam-shape specimens were prepared and divided into 2 groups according to liner application. The specimens in each group were subdivided into 3 subgroups in accordance with 3 different veneer thicknesses. A fracture mechanics test was used on each specimen, and the energy release rate, G, and phase angle, ψ, were calculated according to the experimental results. A video microscope was used to monitor the crack propagation, and a scanning electron microscope was used to identify the fracture mode after testing. Two-way ANOVA and the Tukey honestly significant difference test were performed to analyze the experimental data (α=.05) . RESULTS: At each phase angle, the interfaces without a liner had higher mean G values than the interfaces with a liner. Both of the interfaces showed mixed failure mode with thin layers of a veneer or a liner that remained on the zirconia surfaces. CONCLUSIONS: Liner application before veneering reduced the interface toughness between zirconia and veneer.
Authors: Antonios L Theocharopoulos; Andrew J Bushby; Ken My P'ng; Rory M Wilson; K Elizabeth Tanner; Michael J Cattell Journal: J Adv Prosthodont Date: 2016-12-15 Impact factor: 1.904