Hydrofluoric acid concentrations: Effect on the cyclic load-to-failure of machined lithium disilicate restorations

Prochnow, Catina; Venturini, Andressa Borin; Guilardi, Luís Felipe; Pereira, Gabriel Kalil Rocha; Burgo, Thiago A. L.; Bottino, Marco C.; Kleverlaan, Cornelis J.; Valandro, Luiz Felipe

doi:10.1016/j.dental.2018.06.028

Cited by 38 publications

(9 citation statements)

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“…When recommending a combination of acid concentration and exposure time, other factors that were not tested in the current study should also be evaluated, mainly the strength of the ceramic after acid etching and bonding and its optical properties. Prochnow et al [22] evaluated the effects of different HF acid concentrations of 3%, 5% or 10% on the cyclic load-to-failure of CAD-CAM lithium disilicate crowns cemented by resin cement and found no negative effect of the different HF concentrations. Similarly, in a previous study by Prochnow et al [28], the surface roughness and flexural strength of e.max CAD blocks were tested after using distinct HF acid concentrations of 3%, 5% or 10%.…”

Section: Discussionmentioning

confidence: 99%

“…Studies examining the effect of overetching (higher acid concentration and/or longer exposure time) on the bond strength (SBS) of lithium disilicate to resin cement have led to contradictory results. Prochnow et al [22] evaluated the effects of different HF acid concentrations on the cyclic load-to-failure of CAD-CAM lithium disilicate crowns cemented by resin cement to dentin and found no negative effect of the different HF concentrations. Fonzar et el.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Different Surface Treatments of Lithium Disilicate on the Adhesive Properties of Resin Cements

et al. 2021

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The aim of the current study was to evaluate the influence of hydrofluoric (HF) acid concentration and conditioning time on the shear bond strength (SBS) of dual cure resin cement to pressed lithium disilicate ceramic compared to treatment with an Etch and Prime self-etching glass-ceramic primer (EP). A total of 100 samples of pressed lithium disilicate (IPS e.max Press, Ivoclar Vivadent) were randomly divided into five groups (n = 20) according to surface treatment: two different concentrations of HF (5% or 9%), for different durations (20 or 90 s), or treatment with EP. Adhesion of light-cured resin cement to the treated surface was tested by the SBS test. The substrate surfaces of the specimen after failures were examined by SEM. Data were analyzed using Weibull distribution. The highest cumulative failure probability of 63.2% of the shear bond strength (η parameter) values was in the 9% HF −90 s group (17.71 MPa), while the lowest values were observed in the 5% HF −20 s group (7.94 MPa). SBS values were not affected significantly by the conditioning time (20 s or 90 s). However, compared to treatment with 5% HF, surface treatment with 9% HF showed a significantly higher η (MPa) as well as β (reliability parameter). Moreover, while compared to 9% HF for 20 s, EP treatment did not differ significantly in SBS values. Examination of the failure mode revealed a mixed mode of failure in all the groups. Within the limits of this study, it is possible to assume that IPS e.max Press surface treatment with 9% HF acid for only 20 s will provide a better bonding strength with resin cement than using 5% HF acid.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Different Surface Treatments of Lithium Disilicate on the Adhesive Properties of Resin Cements

et al. 2021

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“…Some authors have advocated the use of 5% HF acid to reduce the risk of defect formation on the ceramic surface and their propagation in the bulk structure of the LDG restoration . Some others reported no significant differences between 5% and 10% HF etching in terms of bond strength to LDG ceramic and, most importantly, of cyclic load‐to‐failure of lithium disilicate crowns . Therefore, making use of different combinations of HF concentrations and etching times appears reasonable, provided that over‐etching is avoided.…”

Section: Discussionmentioning

confidence: 99%

“…47 Some others reported no significant differences between 5% and 10% HF etching in terms of bond strength to LDG ceramic 48 and, most importantly, of cyclic load-tofailure of lithium disilicate crowns. 49 Therefore, making use of different combinations of HF concentrations and etching times appears reasonable, provided that over-etching is avoided. As to alternative FIGURE 7 Representative scanning electron microscope images of the margin quality before and after thermomechanical loading in the 90 rounded shoulder group (A and B) and in the minimally invasive chamfer group (C and D)…”

Section: Clausen Et Al Evaluated the Influence Of Different Preparatmentioning

confidence: 99%

Influence of preparation designs on marginal adaptation and failure load of full‐coverage occlusal veneers after thermomechanical aging simulation

Angerame

Biasi

Agostinetto³

et al. 2019

J Esthet Restor Dent

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Objectives To evaluate the fracture resistance and marginal quality of maxillary molars restored using lithium disilicate glass‐ceramic (LDG) occlusal veneers with two preparation designs. Methods Sixteen extracted maxillary molars were assigned to two groups (n = 8). In group 1 (G1), the teeth received a preparation for a conservative full‐coverage occlusal veneer restoration with a 90° rounded shoulder margin. In group 2 (G2), the teeth underwent a 1‐mm cusp reduction with a marginal chamfer. LDG restorations (IPS e.max CAD) were obtained with the Cerec 3 CAD/CAM system and luted with Variolink II cement. After thermomechanical aging (1 250 000 cycles), the specimens were loaded to fracture. A semiquantitative marginal seal evaluation was performed observing resin replicas of the specimens at the scanning electron microscope. Cement thickness was assessed at the stereomicroscope on sectioned specimens. Collected data were statistically analyzed by parametric and nonparametric tests. Results The maximum load to fracture was 2395.01 ± 150.96 N in G1 and 2408.39 ± 112.66 N in G2. Most of the observed specimens exhibited restorable fractures and continuous margins. Cement thickness was 132 ± 38 μm in G1 and 150 ± 41 μm in G2. No differences between the groups emerged. Conclusion This study demonstrated similar satisfactory performance of the two considered preparations designs for occlusal veneer with LDG. Clinical Significance A new minimally invasive occlusal veneer preparation with marginal chamfer exhibited promising fracture resistance and marginal adaptation that were comparable to those of a standard conservative preparation for the restoration of molars with CAD/CAM lithium disilicate occlusal veneers.

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“…For LS 2 , 20 s HF etching (at 5% concentration) is suggested, that is a shorter time than requested for feldspathic and leucite-based ceramics (generally 60 s). Higher HF concentrations (9-10%) and longer etching times have been shown to be too aggressive and can introduce relevant damages, not only to the surface but also to the internal microstructure of the material, negatively influencing mechanical performance (reduction of flexure strength), adhesion potential and long-term success of ceramic restorations, particularly when thickness is low [38][39][40][41]. Another system to create surface microirregularities is sandblasting LS 2 with aluminum oxide particles.…”

Section: Surface Treatment and Cementationmentioning

confidence: 99%

Current status on lithium disilicate and zirconia: a narrative review

et al. 2019

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Background: The introduction of the new generation of particle-filled and high strength ceramics, hybrid composites and technopolymers in the last decade has offered an extensive palette of dental materials broadening the clinical indications in fixed prosthodontics, in the light of minimally invasive dentistry dictates. Moreover, last years have seen a dramatic increase in the patients' demand for non-metallic materials, sometimes induced by metal-phobia or alleged allergies. Therefore, the attention of scientific research has been progressively focusing on such materials, particularly on lithium disilicate and zirconia, in order to shed light on properties, indications and limitations of the new protagonists of the prosthetic scene. Methods: This article is aimed at providing a narrative review regarding the state-of-the-art in the field of these popular ceramic materials, as to their physical-chemical, mechanical and optical properties, as well as to the proper dental applications, by means of scientific literature analysis and with reference to the authors' clinical experience. Results: A huge amount of data, sometimes conflicting, is available today. Both in vitro and in vivo studies pointed out the outstanding peculiarities of lithium disilicate and zirconia: unparalleled optical and esthetic properties, together with high biocompatibility, high mechanical resistance, reduced thickness and favorable wear behavior have been increasingly orientating the clinicians' choice toward such ceramics. Conclusions: The noticeable properties and versatility make lithium disilicate and zirconia materials of choice for modern prosthetic dentistry, requiring high esthetic and mechanical performances combined with a minimal invasive approach, so that the utilization of such metal-free ceramics has become more and more widespread over time.

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Hydrofluoric acid concentrations: Effect on the cyclic load-to-failure of machined lithium disilicate restorations

Cited by 38 publications

References 54 publications

Effect of Different Surface Treatments of Lithium Disilicate on the Adhesive Properties of Resin Cements

Effect of Different Surface Treatments of Lithium Disilicate on the Adhesive Properties of Resin Cements

Influence of preparation designs on marginal adaptation and failure load of full‐coverage occlusal veneers after thermomechanical aging simulation

Current status on lithium disilicate and zirconia: a narrative review

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