State of the art of zirconia for dental applications
TL;DR: The two main processing techniques, soft and hard machining, are assessed in the light of their possible clinical implications and consequences on the long-term performance of zirconia.
About: This article is published in Dental Materials.The article was published on 2008-03-01. It has received 1696 citations till now.
Citations
More filters
TL;DR: It was concluded that hand layered zirconia fixed partial dentures have better esthetics than monolithic zirConia fixedpartial dentures.
Abstract: Edentulism and dental disease have a major effect on the standard of lifetime of patients. Fixed partial dentures have become the treatment of choice for many people for the replacement of edentulous space in the oral cavity. Therefore, it is of interest to correlate and compare the esthetics between monolithic zirconia and hand layered zirconia among fixed partial dentures in Saveetha Dental College. 100 patients who monolithic zirconia and hand layered zirconia had fixed partial dentures were included within the study. Pink and white esthetic scores were evaluated. Data collected were entered in SPSS and analyzed through Chi square test. It was observed that hand layered zirconia have better white esthetic score (p<0.000) and pink esthetic score (p<0.003) when compared to monolithic zirconia fixed partial dentures, which were statistically significant. It was concluded that hand layered zirconia fixed partial dentures have better esthetics than monolithic zirconia fixed partial dentures.
TL;DR: In this paper , the elastic modulus and Poisson's ratio of a resin cement with distinct viscosities were evaluated to evaluate the static and fatigue strength of a translucent zirconia (4Y-PSZ) after air-abrasion surface treatment.
Abstract: The purpose of the present study was to characterize the elastic modulus and Poisson’s ratio of a resin cement with distinct viscosities, and to evaluate their impact on the static and fatigue strength of a translucent zirconia (4Y-PSZ) after air-abrasion surface treatment. Bar-shaped specimens of two different viscosities of resin cement (high and low) were obtained (25 × 10 × 3 mm). Sonelastic and Maxwell principles tests were performed to determine the elastic modulus and Poisson’s ratio of each resin cement. Disc-shaped specimens of 4Y-PSZ were made (Ø = 15 mm, 1.2 mm in thickness) for the mechanical tests and allocated into groups according to two factors: surface treatment (presence or absence of air-abrasion with alumina particles; 45 μm grain-size); cement (absence, low or high viscosity). The static (n = 10) and cyclical (n = 15) biaxial flexural strength tests were performed by piston-on-three-balls geometry. A fatigue strength test was executed (20 Hz, initial stress of 60 MPa [12% of the mean static biaxial flexural strength], followed by increments of 25 MPa [5% of the mean static biaxial flexural strength] at each step of 10,000 cycles until the failure). The obtained data were analyzed by Weibull analysis. Survival rates were tabulated by the Kaplan-Meier test. Complementary analyses of surface roughness, topography, cross-sectional interfacial zone, fractography, and zirconia crystalline content (X-ray diffraction) were also performed. The evaluated resin cements with high and low viscosity presented similar elastic modulus (13.63 GPa; 12.74 GPa) and Poisson’s ratio (0.32; 0.30), respectively. The air-abraded groups depicted higher mechanical strength of the zirconia ceramics than non-abraded groups (p˂ 0.05), regardless of the resin cement. 4Y-PSZ adhesively bonded to a high or low viscosity resin cement have statistically similar behavior (p˃ 0.05). The mechanical structural reliability of the 4Y-PSZ was not affected by the factors. Therefore, resin cement with high and low viscosity presented similar properties and potential to fill the zirconia surface, and did not affect the mechanical behavior of 4Y-PSZ. However, the air-abrasion surface treatment increased the static and fatigue flexural strength of the translucent zirconia.
TL;DR: In this paper , the effect of plasma-enhanced chemical vapor deposition (PECVD) with silicon hydride (SiH4) at different times on HT-zirconia surface characteristics and bonding of composite cement before and after thermocycling was evaluated.
Abstract: PURPOSE
To evaluate the effect of plasma-enhanced chemical vapor deposition (PECVD) with silicon hydride (SiH4) at different times on HT-zirconia surface characteristics and bonding of composite cement before and after thermocycling.
MATERIALS AND METHODS
Blocks of HT zirconia were obtained, polished, sintered and divided into five groups, according to PECVD time (n = 31): Zr-30 (30 s), Zr-60 (60 s), Zr-120 (120 s) and Zr-300 (300 s). The control group (Zr-0) did not receive PECVD. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS) in conjunction with field-emission scanning electron microscopy (FE-SEM), x-ray photoelectron spectroscopy (XPS), goniometry, and profilometry tests were used for chemical and topographic characterization. Monobond N silane (Ivoclar Vivadent) was applied to the surface, and a cylinder of composite cement (Variolink N) was made (3 x 3 mm). Half of the specimens of each group were stored for 24 h or subjected to thermocycling (6 x 103 cycles). A shear bond strength (SBS) test was performed. Results were subjected to one-way ANOVA and Tukey's tests (α = 0.05).
RESULTS
For experimental groups, XPS showed that formation of Si-O bonds contributed to increased surface free energy (SFE). FE-SEM and EDS showed that the longer the deposition time, the greater the amount of silicon on the surface. Zr-60 and Zr-300 presented higher and lower surface roughnesses, respectively. The silicon penetrated the microstructure, causing higher stress concentrations. The bond strength to composite cement was improved after all PECVD deposition times.
CONCLUSION
The PECVD technique with SiH4, associated with chemical treatment with primer based on silane methacrylate, is a solely chemical surface treatment capable of maintaining bonding between composite cement and HT zirconia.
TL;DR: In this paper, the isotherm levels, above the monoclinic-tetragonal (m −t) transition temperature in ZrO2 (1170°C), were in the range 1200 and 1300°C.
Abstract: Composite ZrO2-NiO powders synthesised, via the oxidation of Ni40-Zr60 alloy, and ball milled to sizes below 90 nm were spark plasma sintered. The isotherm levels, above the monoclinic–tetragonal (m–t) transition temperature in ZrO2 (1170°C), were in the range 1200 and 1300°C. Microstructures with grain sizes between 100 and 900 nm were achieved. The X-ray diffraction patterns of the sintered samples revealed that the m–t transformation in ZrO2 was preserved. The fraction of tetragonal phase, between 25 and 45%, increases with the isotherm level. Such partial stabilisation of the tetragonal phase is attributed to the presence NiO in ZrO2.
References
More filters
TL;DR: This review takes into account the main results achieved up to now, and is focused on the role that microstructural characteristics play on the TZP ceramics behaviour in ball heads, namely mechanical properties and their stability, wear of the UHMWPE paired to TZp, and their influence on biocompatibility.
2,380 citations
"State of the art of zirconia for de..." refers background in this paper
...icated to magnesia partially stabilized zirconia (Mg-PSZ) for possible biomedical applications, this material has not been successful due mainly to the presence of porosity, associated with a large grain size (30–60 m) that can induce wear [14,16]....
[...]
...Biomedical grade zirconia usually contains 3 mol% yttria (Y2O3) as a stabilizer (3Y-TZP)[16]....
[...]
TL;DR: In this article, a review on the science of the t-m transformation in ZrO2 and its application in the modeling of transformation-toughhening behavior, while also summarizing the microstructural control needed to use the benefits in ZRO2-toughened ceramics.
Abstract: The recognition of the potential for enhanced fracture toughness that can be derived from controlled, stress-activated tetragonal (t) to monoclinic (m) transformation in ZrO2-based ceramics ushered in a new era in the development of the mechanical properties of engineering ceramics and provided a major impetus for broader-ranging research into the toughening mechanisms available to enhance the fracture properties of brittle-matrix materials. ZrO2-based systems have remained a major focal point for research as developments in understanding of the crystallography of the t→m transformation have led to more-complete descriptions of the origins of transformation toughening and definition of the features required of a transformation-toughening system. In parallel, there have been significant advances in the design and control of microstructure required to optimize mechanical properties in materials developed commercially. This review concentrates on the science of the t→m transformation in ZrO2 and its application in the modeling of transformation-toughening behavior, while also summarizing the microstructural control needed to use the benefits in ZrO2-toughened ceramics.
1,552 citations
"State of the art of zirconia for de..." refers background in this paper
...Although many types of zirconia-containing ceramic systems are currently available [14,15], only three are used to date in dentistry....
[...]
TL;DR: In this article, the content of free ZrO2 in partially stabilized zirconia ceramics by X-ray diffraction techniques was determined by linear calibration curves.
Abstract: Linear calibration curves were developed for determining the content of free ZrO2 in partially stabilized zirconia ceramics by X-ray diffraction techniques. Two methods were studied. The matrix method, in which free ZrO2 was considered to be distributed in a matrix (the cubic phase), gave approximately equal mass absorption coefficients for the monoclinic and cubic phases. The polymorph technique, in which the cubic phase was considered to be a polymorph of ZrO2 and in which integrated intensities were used, gave the better results.
1,302 citations
"State of the art of zirconia for de..." refers background in this paper
...007 t → m transformation, efficiently arresting crack propagation and leading to high toughness [1,4,5]....
[...]
TL;DR: In this article, the conditions for the retention of a zirconia-rich tetragonal phase at ambient temperature were established and the existence of a miscibility gap, closed below the solidus temperature, in the yttria-rich solid solution region was proposed.
Abstract: Metastable and equilibrium phase relationships in the system ZrO2:YO1.5 have been studied by X-ray diffraction. The conditions for the retention of a zirconia-rich tetragonal phase at ambient temperature are established. The existence of a miscibility gap, closed below the solidus temperature, in the yttria-rich solid solution region is proposed. Some evidence for partially ordered phases is presented.
1,170 citations
"State of the art of zirconia for de..." refers background in this paper
...Higher sintering temperatures and longer sintering times lead to larger grain sizes [21,24,25]....
[...]
...From the phase diagram established by Scott, 3Y-TZP contains some amount of cubic zirconia [24]....
[...]
TL;DR: The aim of this paper is to review and analyze the current knowledge on ageing process and on its effect on the long term performance of implants in order to distinguish between scientific facts and speculation.
1,024 citations