Fracture load of two thicknesses of different zirconia types after fatiguing and thermocycling

Alraheam, Islam Abd; Donovan, Terry; Boushell, Lee W.; Cook, Ryan; Ritter, André V.; Sulaiman, Taiseer A.

doi:10.1016/j.prosdent.2019.05.012

Cited by 31 publications

(34 citation statements)

References 21 publications

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“…Studies that evaluate the optical properties of the ceramics often immersed the samples in artificial saliva and other beverages, but additional studies used thermocycling the materials at different temperatures and for several cycles simulating the oral environment [33,34]. For this study, 10,000 cycles were elected to represent ten years of oral environment [35][36][37].…”

Section: Discussionmentioning

confidence: 99%

Effect of Thermocycling, Surface Treatments and Microstructure on the Optical Properties and Roughness of CAD-CAM and Heat-Pressed Glass Ceramics

2020

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Dental ceramic restorations are widely spread nowadays due to their aesthetics and biocompatibility. In time, the colour and structure of these ceramic materials can be altered by aging processes. How does artificial aging affect the optical and surface roughness of ceramics? This study aims to assess the effect of thermocycling, surface treatments and microstructure upon translucency, opalescence and surface roughness on CAD-CAM and heat-pressed glass-ceramic. Forty-eight samples (1.5 mm thickness) were fabricated from six types of A2 MT ceramic: heat-pressed and milled glass-ceramic (feldspathic, lithium disilicate and zirconia reinforced lithium silicate). The samples were obtained respecting the manufacturer’s instructions. The resulted surfaces (n = 96) were half glazed and half polished. The samples were subjected to thermocycling (10,000 cycles) and roughness values (Ra and Rz), colour coordinates (L*, a*, b*) and microstructural analyses were assessed before and after thermocycling. Translucency (TP) and opalescence (OP) were calculated. Values were statistically analysed using ANOVA test (one way). TP and OP values were significantly different between heat-pressed and milled ceramics before and also after thermocycling (p < 0.001). Surface treatments (glazing and polishing) had a significant effect on TP and OP and surface roughness (p < 0.05). The heat-pressed and milled zirconia reinforced lithium silicate glass-ceramic experienced a loss in TP and OP. Ra and Rz increased for the glazed samples, TP and OP decreased for all the samples after thermocycling. Microstructural analyse revealed that glazed surfaces were more affected by the thermocycling and especially for the zirconia reinforced lithium silicate ceramic. Optical properties and surface roughness of the chosen ceramic materials were affected by thermocycling, surface treatments and microstructural differences. The least affected of the ceramics was the lithium disilicate ceramic heat-pressed polished and glazed.

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Section: Discussionmentioning

confidence: 99%

Effect of Thermocycling, Surface Treatments and Microstructure on the Optical Properties and Roughness of CAD-CAM and Heat-Pressed Glass Ceramics

2020

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“…Only one type of zirconia material based on its yttria concentration was evaluated in this study. There is evidence that 5Y (5 mol% yttria) zirconia may not have the ability to undergo phase transformation as 3Y‐zirconia, and therefore may be more susceptible to crack propagation and fracture 61 . Moreover, one brand of zirconia was evaluated, and it is notable that not all zirconia materials are manufactured equivalently.…”

Section: Discussionmentioning

confidence: 99%

Monolithic Zirconia Partial Coverage Restorations: An In Vitro Mastication Simulation Study

Gupta

Abdulmajeed

Donovan

et al. 2020

Journal of Prosthodontics

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Purpose To evaluate the survival rate (fatigue resistance), bonding efficiency and marginal integrity of monolithic zirconia partial and full coverage single restorations adhesively bonded to the tooth structure using air‐particle abrasion, a primer with 10‐methacryloyloxydecyl dihydrogen phosphate and a composite‐resin cement (APC) protocol. Materials and Methods Extracted human premolars (N = 32) were randomly divided into four groups of eight specimens each. Premolars were prepared for the following restorations: full crown (group 1, control), mesial‐occlusal‐distal‐facial onlay (MODF, group 2) preserving 2 mm facio‐lingual functional cusp width, mesial‐occlusal‐distal‐lingual onlay (MODL, group 3) preserving 2 mm facio‐lingual nonfunctional cusp width, mesial‐occlusal‐distal‐buccal‐lingual onlay (MODBL, group 4), overlay preparation. All restorations were milled from monolithic 3 mol% yttria (3Y) zirconia blocks (ZirCad, A1 LT, Ivoclar Vivadent) with CAD/CAM software presets at minimum occlusal and axial thicknesses of 1 mm. The intaglio surface of the restorations was air‐particle abraded (50 µm Al2O3, 2‐Bar pressure, 15 s, 10 mm distance) and primed. An adhesive cement system was used to bond the restorations. Each group was subjected to thermomechanical loading for 1.2 million cycles (force = 70 N, 1.4 Hz) with simultaneous thermocycling (5‐55°C, 30 s dwell time) using a mastication simulator. All specimens were examined under scanning electron microscope (SEM) analysis (30, 100, and 150×) to evaluate cracks and marginal defects. Fracture of restoration and/or fracture within tooth structure, and debonding were considered modes of failure. Results One specimen from group 2 debonded at 632,000 cycles. None of the specimens failed due to fracture. SEM analysis at 30× indicated marginal integrity issue of the remaining seven intact specimens of group 2 in the area of antagonist contact. No specimens from group 1, 3, and 4 demonstrated marginal integrity issue at 30×. None of the specimens demonstrated any microcrack at 100× and150×. Conclusions Due to its fatigue resistance, 3Y‐zirconia is a viable option for partial and full coverage single restorations. Following a strict bonding protocol, zirconia demonstrated durable adhesion to the tooth structure. Occlusal contact on restoration margins should be avoided.

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“…It is known that increasing yttria mol% concentration significantly negatively affects the mechanical properties of zirconia. [14][15][16] In an elemental analysis study by X-ray fluorescence (XRF), Kolakarnprasert et al, 17 reported that Katana UTML zirconia showed the highest yttria content of 5.4 mol% while Katana STML zirconia had yttria content of 4.8 mol%. The difference in yttria mol% concentration results in different zirconia-phase composition.…”

Section: Discussionmentioning

confidence: 99%

Fracture Load of Different Zirconia Types: A Mastication Simulation Study

Abdulmajeed

Sulaiman

Abdulmajeed

et al. 2020

Journal of Prosthodontics

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Purpose: To assess the effect of yttria mol% concentration and material thickness on the biaxial fracture load (N) of zirconia with and without mastication simulation. Materials and methods: Disk-shaped specimens (N = 120) of 3 mol% yttriapartially stabilized zirconia, 3Y-PSZ (Katana High Translucent, Kuraray Noritake), 4 mol% yttria-partially stabilized zirconia, 4Y-PSZ (Katana Super Translucent Multi Layered) and 5 mol% Yttria-partially stabilized zirconia, 5Y-PSZ (Katana Ultra Translucent Multi Layered) were prepared to thicknesses of 0.7 and 1.2 mm. For each thickness, the biaxial fracture load (N) was measured with and without mastication simulation with 1.2 million cycles at a 110-N load and simultaneous thermal cycling at 5°C to 55°C. The data were analyzed by three-way Analysis of Variance (α = 0.05) and Tukey-Kramer adjusted multiple comparison test. Results: Yttria mol% concentration and material thickness had a statistically significant effect on the mean biaxial fracture load (F = 388.16, p < 0.001 and F = 714.33, p < 0.001 respectively). The mean biaxial fracture load ranged from the highest to the lowest; 3Y-PSZ, 4Y-PSZ, and 5Y-PSZ (p = 0.012). The mean biaxial fracture load of the 1.2 mm thickness groups was significantly higher than 0.7 mm thickness at any given condition (p = 0.002). Not all specimens survived the mastication simulation protocol. Fifty percent of the 0.7-mm-thick 4Y-PSZ specimens, 70% of the 0.7-mm-thick 5Y-PSZ specimens and 20% of 1.2-mm-thick 5Y-PSZ specimens fractured during mastication simulation. Mastication simulation had no statistically significant effect on the biaxial fracture load (F = 1.24, p = 0.239) of the survived specimens. Conclusions: Lowering yttria mol% concentration and increasing material thickness significantly increases the fracture load of zirconia. At 0.7 mm thickness, only 3Y-PSZ survived masticatory simulation. A minimum material thickness of 1.2 mm is required for 4Y-PSZ or 5Y-PSZ.

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Fracture load of two thicknesses of different zirconia types after fatiguing and thermocycling

Cited by 31 publications

References 21 publications

Effect of Thermocycling, Surface Treatments and Microstructure on the Optical Properties and Roughness of CAD-CAM and Heat-Pressed Glass Ceramics

Effect of Thermocycling, Surface Treatments and Microstructure on the Optical Properties and Roughness of CAD-CAM and Heat-Pressed Glass Ceramics

Monolithic Zirconia Partial Coverage Restorations: An In Vitro Mastication Simulation Study

Fracture Load of Different Zirconia Types: A Mastication Simulation Study

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