The effect of adding silica to zirconia to counteract zirconia’s tendency to degrade at low temperatures

Nakamura, Takashi; Usami, Hirofumi; Takeuchi, Miyuki; Nishida, Hisataka; Sekino, Tohru; Yatani, Hirofumi

doi:10.4012/dmj.2010-142

Cited by 25 publications

(21 citation statements)

References 22 publications

(26 reference statements)

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“…Hence, the importance of the grain size factor is highlighted: larger tetragonal grain size leads to a lower stability to phase transformation. 21,22 Despite not causing deleterious effects on the mechanical performance, the evaluated aging regimens promoted an extensive increase in m-phase content and had a small influence on surface roughness (Table). The storage and the mechanical cycling regimens led to lower m-phase content, and resulted in a limited effect on roughness.…”

Section: Discussionmentioning

confidence: 99%

Mechanical behavior of yttria-stabilized tetragonal zirconia polycrystal: Effects of different aging regimens

et al. 2017

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This study aimed to characterize and compare the effect of different aging regimens on surface characteristic (topography and roughness), structural stability (phase transformation) and mechanical performance (Weibull analysis) of a Y-TZP ceramic. Discs (15 × 1.2 mm; VITA In-Ceram YZ) were prepared according to ISO 6872-2015 for biaxial flexural strength testing and randomly assigned into five groups (n = 30): as-sintered, no aging treatment (CTRL); 20 h in autoclave at 134°C, 2 bar pressure (AUT); intermittent mechanical loading at 20 Hz/10 6 load pulses (MechLoad); AUT followed by MechLoad (AUT+MechLoad); and storage in distilled water at 37°C, for 1 year (STO). The following analyses were performed: roughness (n = 30), surface topography (n = 2), phase transformation (n = 2) and biaxial flexure strength (n = 30). Phase transformation (increase of m-phase content) was shown to be a spontaneous, unavoidable and time-dependent process, occurring even under ambient conditions (dry storage after 1 year = 6.0% increase), and is considerably accelerated in the presence of moisture (STO = 17.6%; AUT= 63.1%; and AUT+MechLoad = 59.9%). For roughness parameters, only Ra was affected by aging, and the highest values were observed for AUT+MechLoad (0.25 ± 0.07 µm). For Weibull analysis, structural reliability (Weibull moduli) and characteristic strength were not impaired after aging, and some aging conditions led to increased values (highest weibull moduli in AUT, and highest characteristic strength in STO). Phase transformation proves to be a time-dependent spontaneous mechanism that is accelerated in the presence of different stimuli. However, none of the aging regimens had a negative effect on the characteristic strength and structural reliability of Y-TZP ceramic.

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Section: Discussionmentioning

confidence: 99%

Mechanical behavior of yttria-stabilized tetragonal zirconia polycrystal: Effects of different aging regimens

et al. 2017

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“…Even when the ambient temperature is low, the crystals degrade due to phase transformation to the monoclinic phase in the presence of atmospheric moisture. Thus, a marked decrease in mechanical strength is a concern regarding Y-TZP 34,35) .…”

Section: Discussionmentioning

confidence: 99%

Zirconia Implants with Laser Surface Treatment: Peri-Implant Bone Response and Enhancement of Osseointegration

Yasuno

Kakura

Taniguchi

et al. 2014

J. Hard Tissue Biology.

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The aim of this study was to prepare zirconia implants with laser-modified surfaces and to evaluate peri-implant tissue response and osseointegration in an animal study. The experimental zirconia implants received one of the following surface treatments and were placed in the tibiae of SD rats: vertical irradiation with a fiber laser (vertical fiber laser), horizontal irradiation with a fiber laser (horizontal fiber laser), vertical irradiation with a Neodymium-doped yttrium orthovanadate (YVO4) laser (vertical YVO4 laser), and horizontal irradiation with a YVO4 laser (horizontal YVO4 laser). The control implants were smooth surfaced. Tibiae with implant bodies were collected 28 days after implant placement, and removal torque values were measured. Tissue sections were prepared for light microscopy, and the bone-implant contact (BIC) ratio and the peri-implant bone area (BA) were measured. The vertical fiber-laser implants had a mean BIC that was significantly higher than other implants. The mean BIC of the vertical fiber-laser implants was approximately 4.2 folds of the value of the control implants on the cortical bone side and approximately 2.7 folds of the value of the control implants on the bone marrow side. The mean BA was significantly higher in the vertical YVO4-laser implants. The vertical fiber-laser implants had a mean torque removal value that was approximately 2.4 folds of the value of the control implants and approximately double of the value of the vertical or horizontal YVO4-laser implants. The horizontal fiber-laser implants had a mean removal torque value that was approximately double of the value of the control implants and approximately 1.7 folds of the value of the vertical or horizontal YVO4-laser implants (p<0.05). Both types of lasers were useful in implant surface treatment to enhance osseointegration of zirconia implants.

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“…As for the comparison of the results, the accelerated aging test at 200°C and 2 bar in this experiment was used as the same condition as our former experiment 7) . It is reported that an accelerated aging test performed for one hour at 134°C and 2 bar is equivalent to 3 to 4 years of service in the 37°C intravital environment 19) .…”

Section: Discussionmentioning

confidence: 99%

“…The aging group specimens were immersed in distilled water inside a decomposition vessel consisting of an inner Teflon tube and an outer stainless tube. They were all subjected to an accelerated aging test for 5 h at 200°C and 2 bar using a drying oven (MOV-112, SANYO, Moriguchi, Japan) 7) . Each coping specimen was secured to the titanium abutment with resin cement (SA Luting, Kuraray Medical, Tokyo, Japan).…”

Section: Accelerated Aging Test and Facture Loadmentioning

confidence: 99%

“…Some researchers have reported that the addition of a small amount of silica has effectively suppressed this low temperature degradation (LTD) of Y-TZP 5,6) . In our previous study, we manufactured a new type of Y-TZP material by adding 0.2 mol% of silica and subjected this material to an accelerated hydrothermal aging test, to demonstrate that this silica-doped Y-TZP material is resistant to degradation 7) . The purpose of this study is to determine whether this silica-doped Y-TZP can be milled properly using dental CAD/CAM systems and whether its resistance to LTD is retained after milling, by comparing it with a commercial Y-TZP material.…”

Section: Introductionmentioning

confidence: 99%

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The relationship between milling a new silica-doped zirconia and its resistance to low-temperature degradation (LTD): a pilot study

et al. 2012

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The aim of this study was to determine the machinability of new silica-doped Y-TZP by CAD/CAM and the resistance to low temperature degradation of the milled sample by comparing with a commercial HIP type Y-TZP material. The copings could be milled from silica-doped Y-TZP blocks without chipping, and there was no significant difference between the two types of Y-TZP materials in either the marginal or the inner gap between the abutment and the coping. After aging, the monoclinic content in the commercial Y-TZP copings increased from 25% before testing to 65%, while that of silica-doped Y-TZP copings slightly increased from 23% to 30%. The silica-doped Y-TZP copings did not have any significant difference in fracture load in a comparison between the control group and the aging group, while the commercial Y-TZP copings had a significantly lower fracture load for the aging group than for the control group.

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The effect of adding silica to zirconia to counteract zirconia’s tendency to degrade at low temperatures

Cited by 25 publications

References 22 publications

Mechanical behavior of yttria-stabilized tetragonal zirconia polycrystal: Effects of different aging regimens

Mechanical behavior of yttria-stabilized tetragonal zirconia polycrystal: Effects of different aging regimens

Zirconia Implants with Laser Surface Treatment: Peri-Implant Bone Response and Enhancement of Osseointegration

The relationship between milling a new silica-doped zirconia and its resistance to low-temperature degradation (LTD): a pilot study

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