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To evaluate the effect of the ceramic processing and aging method on the microstructure, optical, and mechanical properties of a third generation ultra-translucent zirconia, yttria ...partially stabilized zirconia (5Y-PSZ).
In-house discs were obtained through uniaxial and isostatic pressing an ultra-translucent Y-PSZ powder and sintering at 1450 °C for 2 h. As control, a commercial disc was milled from pre-sintered blocks fabricated with the same 5Y-PSZ powder through isostatic pressing and sintered under the same protocol. Discs were allocated into three groups according to aging condition as immediate (non-aged) and aged using autoclave or hydrothermal reactor at 134ºC for 20 h at 2.2 bar. Crystalline content and microstructure were evaluated using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Optical properties were determined using reflectance data to calculate the contrast ratio (CR) and translucency parameter (TP). Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength tests.
XRD spectra revealed a prevalence of cubic (70%) and tetragonal (30%) phases, and the SEM images showed a dense fully crystalline ceramic matrix for both materials. Crystalline content and microstructure of the in-house and commercial 5Y-PSZs were not affected by aging. As-sintered 5Y-PSZs demonstrated similar CR (~0.6) and TP (~18) values, as well as Vickers hardness (~14 GPa) and fracture toughness (~3.8 Mpa.m1/2), with no significant alteration after both aging methods. In-house and commercial Y-PSZs Weibull moduli ranged from 3.0 to 5.3. 5Y-PSZ processing methods resulted in similar characteristic strength after sintering (592–618 Mpa). While commercial 5Y-PSZ showed no significant influence of aging on strength, hydrothermal reactor aging significantly decreased the in-house Y-PSZ characteristic strength (474 Mpa). Both 5Y-PSZs demonstrated high reliability up to 300-Mpa strength missions, with no detrimental effect of aging (88–100%).
Irrespective of the processing method, ultra-translucent 5Y-PSZ showed high aging resistance and translucency stability, as well as strength corresponding to the indication up to short-span anterior prostheses.
ABSTRACT This article had the objective of reporting a case of aesthetic rehabilitation with laminated facets from the 14 to the 24 teeth made with IPS E.max Ceram ceramics (Ivoclar-Vivadent), which ...replaced previous unsatisfactory composite resin restorations in the anterior region. The patient had agenesis of 12 and 22 teeth, making it necessary to anatomize the anterior teeth. A digital smile design was first virtually created and then followed by a diagnostic wax-up. The following was performed in a single day: periodontal surgery using the flapless technique to achieve prosthetic space; teeth preparation; an additionalsilicone impression; and multiple provisional restorations of bis-acryl composite resins were fabricated. Fourteen days later, in the second session the ceramic veneers were etched with 5% hydrofluoric acid for 20s; they received a silane application and a silane heat treatment, then lastly an ultrasonic bath. A universal adhesive was used in combination with a light curing cement.Cementation was performed immediately following an occlusal adjustment. The patient returned for a follow-up appointment another fourteen days after the luting process, in which a further occlusal adjustment was performed, and he reported complete satisfaction with the treatment.
RESUMO Este é um relato de caso de reabilitação estética anterior com facetas laminadas dos elementos 14 ao 24 confeccionadas com a cerâmica IPSE.max Ceram (Ivoclar -Vivadent), as quais substituíram facetas de resina composta insatisfatórias dos elementos 13 ao 23. Ressalta-se que o paciente possuía agenesia dos elementos 12 e 22, tornando-se necessária a reanatomização dos dentesanteriores. Inicialmente ocorreu o planejamento digital, seguido pelo enceramento diagnóstico. Foi realizado em consulta única: cirurgia periodontal pela técnica “flapless” para conquista de espaço protético; confecção dos preparos para facetas; moldagem com silicona de adição; e confecção de múltiplos provisórios em resina bisacrilica. Na consulta de cimentação, as peças foram tratadas comácido fluorídrico 5% por 20s; silanizadas com Relyxceramic primer (3M ESPE), submetidas ao tratamento térmico; e banho ultrassônico. O sistema adesivo utilizado foi o Single Bond (3M ESPE) associado ao RelyxVenner (3M ESPE). Imediatamente a cimentação foi realizado um ajuste oclusal. Após 14 dias o paciente retornou para uma nova consulta de acompanhamento, na qual foi realizada mais um ajuste oclusal, e relatou total satisfação com o tratamento realizado.
•HF followed by silane and self-etching ceramic primer promoted higher flexure strength.•Sandblasting with Al2O3 and silicatization produced damages to all ceramics evaluated.•Self-etching ceramic ...primer showed lower roughness values.
To investigate the influence of different surface treatments on biaxial flexure strength, roughness, and surface topography of lithium silicate/disilicate-based ceramics.
225 discs (∅: 12 mm; 1.2 mm – ISO 6872) were made from three ceramics: IPS e.max CAD (LD – Ivoclar Vivadent), Suprinity (LSS - Vita) and Celtra Duo (LSC - Dentsply). The samples were randomly divided into 5 groups (n = 15): no treatment (C); 10% hydrofluoric acid + silane (HF); sandblasting Al2O3 + silane (SB); silicatization + silane (SC); and self-etching ceramic primer (SEP). After surface treatment, a resin cement layer was applied to the disc surface (RelyX U200, 3M ESPE), mechanical cycled (1.2 × 106 cycles, 50 N, 3.8 Hz) and submitted to biaxial flexural strength test (1 mm/min, 1000 Kgf). Roughness, EDS and SEM were also performed. Data were analyzed by one-way ANOVA, Tukey test (5%) and Weibull.
ANOVA revealed that the “surface treatment” factor was significant for all ceramics (p < 0.05). The groups LD-HF (289.30 ± 40) LD-SEP (298. 87 ± 53.29), LSC-HF (195.51 ± 42.12), LSS-HF (269.58 ± 27.07) and LSS-SEP (207.45 ± 28.63) presented significantly higher biaxial flexure strength than respective control groups, except for the LSC-SEP (165.41 ± 33.86), which was statistically similar to the control. The Weibull modulus was significantly higher for the LD-SB, LSC-SC groups. Additionally, the LD-SB, LSC-SC and LSS-HF groups showed higher roughness compared to the other treatments.
HF etching followed by silanization and self-etching ceramic primer are the most suitable surface treatments for lithium silicate/disilicate-based glass-ceramics.
The present work aims to develop a production method of pre-sintered zirconia-toughened-alumina (ZTA) composite blocks for machining in a computer-aided design and computer-aided manufacturing ...(CAD-CAM) system. The ZTA composite comprised of 80% Al2O3 and 20% ZrO2 was synthesized, uniaxially and isostatically pressed to generate machinable CAD-CAM blocks. Fourteen green-body blocks were prepared and pre-sintered at 1000 °C. After cooling and holder gluing, a stereolithography (STL) file was designed and uploaded to manufacture disk-shaped specimens projected to comply with ISO 6872:2015. Seventy specimens were produced through machining of the blocks, samples were sintered at 1600 °C and two-sided polished. Half of the samples were subjected to accelerated autoclave hydrothermal aging (20h at 134 °C and 2.2 bar). Immediate and aged samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Optical and mechanical properties were assessed by reflectance tests and by biaxial flexural strength test, Vickers indentation and fracture toughness, respectively. Samples produced by machining presented high density and smooth surfaces at SEM evaluation with few microstructural defects. XRD evaluation depicted characteristic peaks of alpha alumina and tetragonal zirconia and autoclave aging had no effect on the crystalline spectra of the composite. Optical and mechanical evaluations demonstrated a high masking ability for the composite and a characteristic strength of 464 MPa and Weibull modulus of 17, with no significant alterations after aging. The milled composite exhibited a hardness of 17.61 GPa and fracture toughness of 5.63 MPa m1/2, which remained unaltered after aging. The synthesis of ZTA blocks for CAD-CAM was successful and allowed for the milling of disk-shaped specimens using the grinding method of the CAD-CAM system. ZTA composite properties were unaffected by hydrothermal autoclave aging and present a promising alternative for the manufacture of infrastructures of fixed dental prostheses.
Purpose
To evaluate the reliability and failure modes of ultrathin (0.5 mm) lithium disilicate, translucent and ultra‐translucent zirconia crowns for posterior teeth restorations.
Materials and ...Methods
Fifty‐four mandibular first molar crowns of three ceramic materials: (1) Lithium disilicate (e.max CAD, Ivoclar Vivadent), (2) 3Y‐TZP (Zirconn Translucent, Vipi), and (3) 5Y‐PSZ (Cercon XT, Dentsply Sirona), with 0.5 mm of thickness were milled and cemented onto composite resin abutments. Eighteen samples of each group were tested under mouth‐motion step‐stress accelerated life testing in a humid environment using mild, moderate, and aggressive profiles. Data was subjected to Weibull statistics. Use level curves were plotted and reliability was calculated for a given mission of 100,000 cycles at 100, 200, and 300 N. Fractographic analyses of representative samples were performed in scanning electron microscope.
Results
Beta (β) values suggest that failures were dictated by material's strength for lithium disilicate and by fatigue damage accumulation for both zirconias. No significant differences were detected in Weibull modulus and characteristic strength among groups. At a given mission of 100,000 cycles at 100 N, lithium disilicate presented higher reliability (98% CB: 95–99) regarding 3Y‐TZP and 5Y‐PSZ groups (84% CB: 65%–93% and 79% CB: 37&–94%, respectively). At 200 N, lithium disilicate reliability (82% CB: 66%–91%) was higher than 5Y‐PSZ (20% CB: 4%–44%) and not significantly different from 3Y‐TZP (54% CB: 32%–72%). Furthermore, at 300 N no significant differences in reliability were detected among groups, with a notable reduction in the reliability of all materials. Fractographic analyses showed that crack initiated at the interface between the composite core and the ceramic crowns due to tensile stress generated at the intaglio surface.
Conclusions
Ultrathin lithium disilicate crowns demonstrated higher reliability relative to zirconia crowns at functional loads. Lithium disilicate and zirconia crown's reliability decreased significantly for missions at higher loads and similar failure modes were observed regardless of crown material. The indication of 0.5 mm thickness crowns in high‐load bearing regions must be carefully evaluated.
Clinical Significance
Ultraconservative lithium disilicate and zirconia crowns of 0.5 mm thickness may be indicated in anterior restorations and pre‐molars. Their clinical indication in high‐load requirement regions must be carefully evaluated.
The aim of this study was to evaluate the effect of two finishing techniques, glazing or polishing, in comparison with the as‐cut condition, on the biaxial‐flexural‐strength (BFS) of a ...zirconia‐reinforced lithium silicate ceramic (ZLS). Cylinders were milled from CAD/CAM blocks and sliced to obtain disc‐shaped specimens (ISO6872:2015). Polished and glazed specimens were processed following the manufacturer's instructions. Thirty‐three specimens were obtained for each condition and microstructural and BFS/fractographic characterizations were performed. BFS and roughness data were analyzed using Weibull statistics and ANOVA one‐way with Tukey post‐hoc test, respectively. While a rougher surface was observed for as‐cut specimens, smoother surfaces were observed for polished and glazed ZLS at microscopical evaluation and confirmed through surface‐roughness evaluation. X‐ray spectra depicted a glass phase for all groups and characteristic metasilicate, lithium disilicate, and lithium phosphate peaks for the as‐cut and polished specimens. Glazed specimens showed higher characteristic strength than polished and as‐cut specimens, which did not differ significantly. While higher Weibull‐modulus was observed for the polished than for the as‐cut specimens, no statistically significant differences were noted between glazed and polished, and between glazed and as‐cut specimens. ZLS presents higher strength when glazed, and polishing increases the structural reliability of the material relative to the as‐cut condition. Both finishing techniques reduced surface roughness similarly.
To characterize the optical and mechanical properties of a commercial and in-house translucent Y-TZP before and after aging in autoclave or hydrothermal reactor.
In-house experimental discs were ...obtained through uniaxial and isostatic pressing a translucent Y-TZP powder and sintering at 1,550 °C/1 h. Commercial discs were milled from pre-sintered blocks fabricated with the same powder through uniaxial and isostatic pressing and sintering. Discs were allocated into three groups according to aging condition: immediate, aged via autoclave, or reactor (134 °C, 20 h, 2.2 bar). Crystalline content and microstructure were evaluated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Residual compressive stress (CS) was determined by Raman spectroscopy. Optical properties were determined by the contrast ratio (CR) and translucency parameter (TP) using reflectance data. Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength tests.
XRD and SEM revealed a typical Y-TZP crystalline content, chiefly tetragonal phase, and a dense crystalline matrix for both processing protocols. Reactor aging triggered a more pronounced t-m transformation relative to autoclave. In-house and commercial Y-TZPs demonstrated similar CR and TP, with reactor aging significantly increasing their translucency. Similarly, reactor aging influenced Vickers hardness and fracture toughness. In-house processed Y-TZP clearly demonstrated the presence of CS, whereas commercial Y-TZP showed no presence of CS. Non-aged in-house Y-TZP resulted in significantly lower characteristic strength relative to commercial Y-TZP. While aging protocols significantly increased the characteristic strength of in-house Y-TZP, reactor significantly decreased commercial Y-TZP characteristic strength. Both Y-TZP processing protocols demonstrated high reliability at high-stress missions, with no detrimental effect of aging.
Laboratory aging methodology significantly influenced optical and mechanical properties of a commercial and in-house translucent Y-TZP.
Two types of high-purity aluminum-stabilized superconducting conductor were developed and produced for use in large-aperture high-field superconducting solenoids. One (DS1) has transverse rectangular ...dimensions of 5.27 mm × 20.1 mm, whereas the other (PS) has 5.52 mm × 30.1 mm. The superconductor for both cables is copper-stabilized NbTi strand woven into a Rutherford cable. The stabilizer for the DS1 conductor is 5N aluminum, whereas the stabilizer for PS is an aluminum alloy of 5N aluminum with a 0.1wt% Ni addition. Continuous unit lengths up to 1700 m are required for production. In total, over 18 000 m are required for this contract. A major goal of the R&D is to produce a cable having high shear strength between Cu and Al boundary while maintaining high residual resistivity ratio (RRR) and strength in the Al parts. We report on the cable mechanical properties, RRR of aluminum, sharing stress between Cu and Al, and critical current (I C ) of the cable, as well as the progress toward the fabrication of long unit lengths for production.
Two types of high-purity aluminum-stabilized superconducting conductor were developed and produced for use in large-aperture high-field superconducting solenoids. One (DS1) has transverse rectangular ...dimensions of 5.27 mm × 20.1 mm, whereas the other (PS) has 5.52 mm × 30.1 mm. The superconductor for both cables is copper-stabilized NbTi strand woven into a Rutherford cable. The stabilizer for the DS1 conductor is 5N aluminum, whereas the stabilizer for PS is an aluminum alloy of 5N aluminum with a 0.1wt% Ni addition. Continuous unit lengths up to 1700 m are required for production. In total, over 18 000 m are required for this contract. A major goal of the R & D is to produce a cable having high shear strength between Cu and Al boundary while maintaining high residual resistivity ratio (RRR) and strength in the Al parts. We report on the cable mechanical properties, RRR of aluminum, sharing stress between Cu and Al, and critical current Formula Omitted of the cable, as well as the progress toward the fabrication of long unit lengths for production.
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