Subcritical crack growth behavior and life data analysis of two types of dental Y-TZP ceramics

Mitov, Gergo; Gessner, Janina; Lohbauer, Ulrich; Woll, K.; Muecklich, Frank; Pospiech, Peter

doi:10.1016/j.dental.2011.03.010

Cited by 32 publications

(22 citation statements)

References 36 publications

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“…The prevailing view, borrowed originally from fundamental studies in the materials science community, 49, 50 is that fatigue can be accounted for by chemically-enhanced, rate-dependent crack growth in the presence of moisture. 51–60 According to this viewpoint, water enters incipient fissures and breaks down cohesive bonds holding the crack walls together. 49, 61 The result is so-called 'subcritical' or 'slow' crack growth (SCG) which progresses steadily over time, accelerating at higher stress levels and ultimately leading to failure.…”

Section: Introductionmentioning

confidence: 99%

Fatigue of dental ceramics

Zhang

Sailer

Lawn

2013

Journal of Dentistry

254

172

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Objectives Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. Data/sources The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Conclusions Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically-assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Clinical significance Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy.

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Section: Introductionmentioning

confidence: 99%

Fatigue of dental ceramics

Zhang

Sailer

Lawn

2013

Journal of Dentistry

254

172

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“…For dental ceramics containing flaws and defects, which can act as localized stress concentrators, although the stresses induced by low mastication loads do not exceed their characteristic strength, these stresses can promote subcritical crack growth, which results in substantial reduction of strength and potential catastrophic failure. 9,10 Therefore, K IC is more predictive than strength, 11 which has been widely accepted as a material parameter for the reliability assessment of ceramic materials. 12,13 …”

Section: Introductionmentioning

confidence: 99%

Influence of cyclic loading on the fracture toughness and load bearing capacities of all-ceramic crowns

Wang

et al. 2013

Int J Oral Sci

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The purpose of this study was to investigate how cyclic loading influenced the fracture toughness of hot-press lithium disilicate and zirconia core materials and whether there was an increase in the propensity for crown failure. Two types of all-ceramic crowns including the IPS e.max Press system (n=24) and the Lava zirconia system (n=24), were selected. Sectioned specimens were subjected to cyclic loading with the maximum magnitude of 200 N (R=0.1) until two million cycles. The material properties including Young's modulus (E) and hardness (H) and the fracture toughness (KIC) of the core materials were evaluated using indentation methods (n=12 each). The load-bearing capacities of the specimens were examined by means of monotonic load to fracture (n=12 each). It was found that the material properties, including E, H and KIC, of the two types of dental ceramics, were reduced. Statistical analysis indicated that there were no significant influences of fatigue loading on material properties E and H for both types of dental ceramics or KIC for zirconia, while for the IPS e.max Press core, KIC, which was parallel to the direction of the lithium disilicate crystals, was significantly reduced (P=0.001). A conclusion was drawn that zirconia possesses high mechanical reliability and sustainable capacity to resist fatigue loading, while fatigue loading remarkably degraded the anisotropic mechanical behaviour of hot-press lithium disilicate ceramics.

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“…The three-unit zirconia framework was designed with a dental CAD program (KaVo multiCAD, KaVo) using a cement spacer of 0.035 mm, a minimum coating thickness of 0.5 mm for the framework and connectors with a minimum area of 9 mm 2 . All restorations were milled with a five-axes milling unit (KaVo Everest engine, KaVo), using two different bur diameters (2.0 and 1.0 mm) and pre-sintered zirconia blanks (Everest ZS, KaVo) that were characterized by a Weibull modulus of 7.58 and a flexural strength of 1431 MPa [28]. All three-unit frameworks were sintered to full density overnight in a special furnace (Everest therm, KaVo) at 1500°C.…”

Section: Prosthodontic Proceduresmentioning

confidence: 99%