Comparative fracture behavior of monolithic and veneered zirconia posterior fixed dental prostheses

Abstract

The purpose of this study was to evaluate and to compare the fracture load and the fracture pattern of monolithic and veneered zirconia posterior fixed dental prostheses (FDPs). Twenty standardized steel dies were prepared to receive posterior 3-unit FDPs. Specimens were randomly divided into 2 groups (n=10): (1) Lava Zirconia, and (2) Lava Plus. All FDPs were cemented using glass ionomer cement and subjected to thermal and mechanical cycling at 5-55ºC with a 30-s dwell time for 120,000 masticatory cycles. All specimens were subjected to a three-point bending test until fracture. Data were statistically analyzed using Student's t test, paired t-test and Weibull statistics (α=0.05). No differences were observed in fracture load between the groups. Veneering ceramic fractured before than framework in veneered zirconia group. The fracture pattern was different. The tested groups demonstrated clinically acceptable fracture load values. Monolithic zirconia solves the chipping problem.

Effect of Thermomechanical and Static Loading on the Load to Fracture of Metal‐Ceramic, Monolithic, and Veneered Zirconia Posterior Fixed Partial Dentures

“…The abutments were positioned on the base to receive posterior 3‐unit FPDs with an intermediate pontic, such that one simulated a first mandibular premolar, and the other simulated a first mandibular molar. The abutments were designed with the following characteristics to simulate clinical conditions: 5 mm in height, 1‐mm wide chamfer, a 6° angle of convergence of the axial walls, and rounded angles . They were air‐abraded with 100 μm alumina particles to eliminate the surface brightness and to create micromechanical retention.…”

“…Zirconia possess low translucency, and the opaque white frameworks must be veneered with porcelain to improve esthetics . The core/veneer interface is one of the weakest aspects of these restorations.…”

“…Furthermore, it has been reported that the veneering ceramic is what modifies the final color of ceramic restorations . In addition, colored zirconia framework does not solve the chipping of the veneering porcelain, and to overcome this problem monolithic zirconia has been introduced to the market, However, due to its recent introduction, studies regarding its behavior are limited …”

“…However, given that numerous intraoral variables are difficult to reproduce in vitro, in addition to the very few studies of validated laboratory tests that allow systematic research, it is very difficult to perform comparisons among different studies on the load to fracture of ceramics . Recent studies have used the aging process or dynamic loading of specimens to simulate clinical conditions and better predict their long‐term success . However, the substantial heterogeneity of data makes comparison of results difficult …”

The effect of repetitive firings on the color of an alumina ceramic system with varying ceramic shade and thickness

“…There are studies reporting that the zirconia bilayered restorations and monolithic zirconia ceramics have the best mechanical properties in dental ceramics era . From another aspect, zirconia bilayered restorations are reported to have negative consequences such as delamination/chipping and incompatibility with veneering ceramics, while monolithic restorations can eliminate these problems . However, it is difficult to provide esthetics with monolithic zirconia restorations .…”