Impact of crystallization firing process on the microstructure and flexural strength of zirconia-reinforced lithium silicate glass-ceramics

Riquieri, Hilton; Monteiro, Jaiane Bandoli; Viegas, Diogo; Campos, Tiago Moreira Bastos; Melo, Renata Marques de; Saavedra, Guilherme de Siqueira Ferreira Anzaloni

doi:10.1016/j.dental.2018.06.010

Cited by 69 publications

(64 citation statements)

References 17 publications

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“…Moreover, the relatively smooth zone of slow crack propagation suggests that the crack may have propagated in the glassy matrix instead of being impeded by the presence of crystals. This could explain the relatively low flexural strength and fracture toughness values for Obsidian, perhaps the result of an incomplete crystallization process …”

Section: Discussionmentioning

confidence: 99%

Fracture Toughness, Flexural Strength, and Flexural Modulus of New CAD/CAM Resin Composite Blocks

Lucsanszky

Ruse

2019

Journal of Prosthodontics

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Purpose:To determine and compare the fracture toughness, flexural strength and flexural modulus of four new, commercially available CAD/CAM resin composite blocks and one new CAD/CAM lithium disilicate glass-ceramic block, tested under dry and aged conditions. Materials and Methods: Three dispersed-fillers resin composite blocks, CERAS-MART, KZR-CAD-HR2, and CAMouflage NOW, one polymer-infiltrated ceramic network resin composite block, Enamic, along with Obsidian, a lithium disilicate glass-ceramic block, were characterized. Fracture toughness was determined through the notchless triangular prism specimen test, while flexural strength and flexural modulus were determined by three-point bend testing. Blocks were cut and ground to obtain (6 × 6 × 6 × 12) mm prisms and 10:1 span-to-thickness ratio bars (n = 25/group); half of the resin composite specimens were aged in 37°C distilled water for 30 days before testing. Fractured surfaces were characterized using a scanning electron microscope. Results were analyzed using Weibull statistics and two-way ANOVA, followed by Scheffé multiple means comparisons (α = 0.05). Results: With regards to fracture toughness, KZR stood out among resin composites with a dry value of 1.37 MPa·m 1/2 ; this was significantly affected by ageing, while the fracture toughness of the other dispersed-fillers resin composite blocks was not. Obsidian had the highest fracture toughness at 1.47 MPa·m 1/2 . With regards to flexural strength, Obsidian > CERASMART = KZR > CAMouflage > Enamic. The flexural strength of the resin composites was lowered by ageing. Enamic was found to have the highest flexural modulus among the resin composites (33.02 GPa), but its value was significantly lower than that of Obsidian (76.46 GPa); flexural modulus was not affected by ageing. Conclusion: There was a significant difference in flexural strength between the materials, but not unanimously in flexural modulus and fracture toughness. The tested resin composite block materials had inferior flexural strength, flexural modulus and fracture toughness compared with the tested lithium disilicate glass-ceramic block (Obsidian). Enamic, the polymer infiltrated ceramic network material, had a significantly higher flexural modulus than the dispersed-fillers materials. Ageing had a deleterious impact on the flexural strength of all RCB, while its effect on the flexural modulus was insignificant. The selection of any restorative material requires a thorough analysis of its advantages and limitations to inform the clinical decision in a case-by-case approach.

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Section: Discussionmentioning

confidence: 99%

Fracture Toughness, Flexural Strength, and Flexural Modulus of New CAD/CAM Resin Composite Blocks

Lucsanszky

Ruse

2019

Journal of Prosthodontics

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“…Fully crystallized ZLS glass-ceramics can be cemented after milling and glazing or polishing, whereas pre-crystallized ZLS glass-ceramics require a further crystallization firing process combined with glazing, additional glazing, or polishing to reach its final esthetic and physical properties. 34 Studies reported in the literature investigated the surface characteristics and optical properties (glazing or polishing) of ZLS glassceramics. 6,11 However, data on the glazing efficiency with or without crystallization are limited.…”

Section: Discussionmentioning

confidence: 99%

“…3 Bahgat et al 38 reported that the higher translucency of ZLS glass-ceramic might be due to its lower (0.5 μm) and more homogeneous crystalline structures (2 types). Riquieri et al 34 also reported many differences in the microstructure of ZLS glassceramics before and after crystallization firing; zirconia grains decreased and nanocrystalline lithium metasilicate peaks (Li2SiO3) were more intense in X-ray diffraction after the crystallization firing process (CFP). Although microstructural differences in the ZLS glassceramic were not evaluated in the present study, the difference in TP values may be due to microstructural changes in the ZLS glass-ceramic and the glazing materials during firing.…”

Section: Discussionmentioning

confidence: 99%

Effect of Surface Finishing Methods and Aging on Surface Roughness and Optical Properties of Zirconia-Reinforced Lithium Silicate Glass-Ceramic

Alp

Subaşı

2019

Cumhuriyet Dental Journal

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Objectives: The effects of three different surface finishing methods and aging on the surface roughness and optical properties of zirconia-reinforced lithium silicate (ZLS) glass-ceramic were investigated. Materials and Methods: Rectangular specimens (0.6 mm thickness) were sliced from ZLS blocks (N=36). Three different types of surface finishing [glazing combined with crystallization (ZLS-CF) or after crystallization (ZLS-G) and polishing (ZLS-P)] (n=12) and 5000 thermocycles were applied. Three sets of measurements were performed before and after aging to determine the color coordinates and surface roughness (Ra) by using a colorimeter and profilometer, respectively. The mean surface roughness (Ra) values were calculated. Color differences and translucency parameter (TP) values were calculated using the color difference ΔEab and TP formulas. One-way ANOVA was used to analyze the color difference, translucency, and surface roughness values (α=.05). Results: Significant differences in the ΔE values were not observed (p=.736) for specimens with different types of surface finishing. A significant difference was observed between the translucency values for different surface finishing groups before aging (p<.001). A significant difference in the surface roughness data between samples with different kinds of surface finishing was observed both before and after aging (p<.001). The ZLS-P group exhibited lowest surface roughness values before and after aging (p<.001). A positive significant correlation between the ΔE and translucency change values was observed in both the ZLS-G (p=.005) and ZLS-P (p<.001) groups. Conclusions: The surface finishing type did not affect the color change of ZLS glass-ceramic. The translucency values for different surface finished ZLS glassceramic specimens changed before aging. After aging, the surface finishing did not affect the translucency of ZLS glass-ceramic. All tested groups exhibited surface roughness values higher than the plaque accumulation threshold (Ra=0.2 mm).

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“…Incorporation of ZrO 2 particles into the glass matrix is an effective method to improve the mechanical properties of glass-ceramics [60,68,71]. The strengthening mechanism of ZrO 2 reinforced glass-ceramics is schematically demonstrated in Figure 11a.…”

Section: Zro 2 -Reinforced Glass-ceramicsmentioning

confidence: 99%

Glass–Ceramics in Dentistry: A Review

2020

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In this review, we first briefly introduce the general knowledge of glass–ceramics, including the discovery and development, the application, the microstructure, and the manufacturing of glass–ceramics. Second, the review presents a detailed description of glass–ceramics in dentistry. In this part, the history, property requirements, and manufacturing techniques of dental glass–ceramics are reviewed. The review provided a brief description of the most prevalent clinically used examples of dental glass–ceramics, namely, mica, leucite, and lithium disilicate glass–ceramics. In addition, we also introduce the newly developed ZrO2–SiO2 nanocrystalline glass–ceramics that show great potential as a new generation of dental glass–ceramics. Traditional strengthening mechanisms of glass–ceramics, including interlocking, ZrO2–reinforced, and thermal residual stress effects, are discussed. Finally, a perspective and outlook for future directions in developing new dental glass–ceramics is provided to offer inspiration to the dental materials community.

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Impact of crystallization firing process on the microstructure and flexural strength of zirconia-reinforced lithium silicate glass-ceramics

Abstract: The CFP had a direct influence on the flexural strength and microstructural characteristics of both ZLS materials.

Cited by 69 publications

References 17 publications

Fracture Toughness, Flexural Strength, and Flexural Modulus of New CAD/CAM Resin Composite Blocks

Fracture Toughness, Flexural Strength, and Flexural Modulus of New CAD/CAM Resin Composite Blocks

Effect of Surface Finishing Methods and Aging on Surface Roughness and Optical Properties of Zirconia-Reinforced Lithium Silicate Glass-Ceramic

Glass–Ceramics in Dentistry: A Review

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