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Li Q, Yang Y, Chen K, Jiang Y, Swain MV, Yao M, He Y, Liang Y, Jian Y, Zhao K. Effect of low-temperature degradation on the fatigue performance of dental strength-gradient multilayered zirconia restorations. J Dent 2024; 142:104866. [PMID: 38281620 DOI: 10.1016/j.jdent.2024.104866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 01/16/2024] [Accepted: 01/25/2024] [Indexed: 01/30/2024] Open
Abstract
OBJECTIVES Fatigue and low-temperature degradation (LTD) are the main factors contributing to zirconia restoration failure. This study evaluated the effect of LTD on the fatigue performance of the novel "strength & shade-gradient" multilayered zirconia restorations. METHODS Discs (15 mm × 1.2 mm) of each yttria content layer from a newly developed strength-gradient multilayered zirconia were fabricated and under accelerated aging in an autoclave at 134℃ for 0 h, 32 h, and 64 h. Then, the phase transformation, microstructure, and mechanical properties after LTD were assessed. In addition, the crown samples, including the multi-Zir, 3Y-Zir, and 5Y-Zir were fabricated, and their monotonic and fatigue load before and after LTD, percentage of fatigue degradation (Sd) and the fracture morphology were investigated. Statistical analyses were performed using paired samples t-test (α' = α/3 = 0.017), one-way ANOVA and Weibull analysis. RESULTS After LTD, the phase transformation, surface roughness, depth of transformed zone, and residual stress were increased and inversely associated with the yttria content. The indentation elastic modulus and hardness after LTD decreased; however, there was no significant difference between the different yttria content layers. The monotonic and fatigue load of multi-Zir restorations decreased, but their Weibull modulus increased, and Sd decreased, similar to 3Y-Zir. The crack origin was associated with the cervical region. CONCLUSION These results show that although LTD reduces the absolute fatigue strength of strength-gradient multilayered zirconia restorations, it also reduces the effect of cyclic fatigue itself on the strength of zirconia (relative to monotonic strength), which might be due to the increase of residual stress. CLINICAL SIGNIFICANCE The novel "strength & shade-gradient" multilayered zirconia restorations show a promising performance during in vitro LTD and fatigue test and their reliability to some extent is comparable to 3Y-Zir. Yet, further in vivo longitudinal studies are warranted to confirm their precise performance.
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Affiliation(s)
- Qiulan Li
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yunxu Yang
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Kuangyao Chen
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yingyu Jiang
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Michael V Swain
- Don State Technical University, Rostov-on-Don 344000, Russia; AMME, Sydney University, Sydney, Australia
| | - Mianfeng Yao
- Xiangya Hospital Central South University, Changsha 410008, China
| | - Ying He
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yujie Liang
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
| | - Yutao Jian
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China; Institute of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China.
| | - Ke Zhao
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
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Aragonez GC, Dalla-Nora F, Soares PM, Pereira GKR, Valandro LF, Dos Santos SS, Rippe MP. Load-bearing capacity under fatigue of bonded-yttria tetragonal zirconia polycrystals and -yttria-stabilized zirconia: Effects of the viscosity of a dual-cured resin cement. J Mech Behav Biomed Mater 2023; 148:106233. [PMID: 37976685 DOI: 10.1016/j.jmbbm.2023.106233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/04/2023] [Accepted: 11/07/2023] [Indexed: 11/19/2023]
Abstract
This study aimed to evaluate the effect of low and high viscosities of dual-cured resin cement on the mechanical fatigue behavior of yttria tetragonal zirconia polycrystals (3Y-TZP) and yttria-stabilized zirconia (4YSZ) adhesively luted to a dentin analogue (glass fiber-reinforced epoxy resin). Ceramic discs were randomly divided into four groups (n = 20) based on the following study factors: dual-cured resin cement viscosities (low and high) and zirconia microstructure (3Y-TZP and 4YSZ). The discs were treated by air abrasion with aluminum oxide particles (50 μm), followed by the application of primer, and then luted with high or low viscosity resin cement to the dentin analogue. Subsequently, the luted sets underwent a step-stress fatigue test, which involved an initial load of 200 N, step increments of 100 N, 10,000 cycles per step, and a frequency of 20 Hz. Data on fatigue failure load (FFL) and the number of cycles for failure (CFF) were collected and analyzed using survival tests, including Kaplan-Meier and Mantel-Cox analyses, as well as Weibull analysis. Additionally, topography analysis, fractographic features, bonding interface analysis, and Raman spectroscopy were performed. The results revealed that 3Y-TZP exhibited superior fatigue behavior compared to 4YSZ, regardless of the viscosity of the resin cement used for luting. Among all groups, 3Y-Low exhibited the best fatigue performance, while 4YSZ luted with low or high viscosity resin cements yielded the lowest fatigue behavior (FFL). There were no significant differences in Weibull modulus among the groups. After air abrasion, both ceramics showed similar topography. Raman analysis indicated that the surface of 3Y-TZP ceramics prior to sintering had a monoclinic phase, which transitioned predominantly to tetragonal phase peaks after sintering. A similar transition was observed in 4YSZ ceramics. In summary, 3Y-TZP exhibited superior mechanical fatigue behavior compared to 4YSZ. The influence of resin cement viscosity on fatigue behavior was more pronounced in 3Y-TZP, with low-viscosity resin cement enhancing its performance. However, the mechanical fatigue behavior of 4YSZ was less affected by the viscosity of the dual-cured resin cement, showing similar results with both low and high viscosities. In conclusion, 3Y-TZP demonstrated superior mechanical fatigue behavior compared to 4YSZ. The impact of resin cement viscosity on fatigue behavior was more pronounced in 3Y-TZP, with low-viscosity resin cement enhancing its performance. Conversely, the mechanical fatigue behavior of 4YSZ was less sensitive to the viscosity of the dual-cured resin cement, resulting in similar outcomes with both low and high viscosities.
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Affiliation(s)
- Gabriela Carrão Aragonez
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Fernanda Dalla-Nora
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Pablo Machado Soares
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Gabriel Kalil Rocha Pereira
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Luiz Felipe Valandro
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Sailer Santos Dos Santos
- Laboratory of Inorganic Materials, Department of Chemistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Marília Pivetta Rippe
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
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Roulet JF, Sinhoreti MAC, Pontes S, Rocha MG. Two-body wear resistance and fatigue survival of new Y-TZP and ATZ ceramics made with a new slip-casting method. J Mech Behav Biomed Mater 2022; 136:105535. [PMID: 36302274 DOI: 10.1016/j.jmbbm.2022.105535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/14/2022] [Accepted: 10/16/2022] [Indexed: 11/06/2022]
Abstract
BACKGROUND Dental zirconium oxide restorations are milled from pre-sintered blocks or disks which are produced either with high isostatic pressure (HIP) or, simpler, a slurry technique. The objective was to perform a fatigue test and an in vitro wear simulation of two ceramics, yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) ceramic and a hybrid zirconium oxide-aluminum oxide ceramic, (ATZ) both produced either the classical way using high isostatic pressure (HIP, control) or with a slurry technique. MATERIALS AND METHODS Ten discs/group were subjected to a cyclic biaxial fatigue test using a staircase approach under water at 37 °C in a dynamic universal testing machine. The 2-body wear test was performed on eight lapped 12 mm thick cylindrical samples subjected to spherical (ø 6 mm) leucite ceramic antagonists in a CS-4 chewing simulator at 49 N force and 0.7 mm lateral movement for 600 k cycles and 4167 thermal cycles (5-55 °C). Volumetric wear was calculated based on laser-scanned surfaces. Selected samples of both tests were viewed in SEM. RESULTS All the ceramic specimens produced using the HIP method survived up to 1.2 M cycles with the maximum load of the equipment (1000 N) loading the specimens up to 1527 MPa. The fatigue limit stress at 1.2 M cycles for the Slurry ATZ samples was 946 MPa. For the Slurry Y-TZP samples the fatigue limit stress at 1.2 M cycles was 658 MPa. At 600 k cycles, all zirconium oxide ceramics showed no measurable wear and had a highly polished appearance. The leucite ceramic antagonists wear developed in a linear way. There was no difference between the materials produced with the slurry and the HIP process. ATZ ceramic produced significantly more wear than 3Y- TZP ceramic. CONCLUSIONS The HIP method provided higher fatigue strength than the Slurry manufacturing method. All HIP ceramics surpassed the limit threshold (1527 MPa) of the testing machine. The tested ceramics did not show any measurable wear but had worn the leucite reinforced glass ceramic antagonists for a considerable amount.
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Affiliation(s)
- Jean-François Roulet
- Center of Dental Biomaterials, Department of Restorative Dental Science, College of Dentistry, University of Florida, Gainesville, FL, USA.
| | - Mario Alexandre Coelho Sinhoreti
- Center of Dental Biomaterials, Department of Restorative Dental Science, College of Dentistry, University of Florida, Gainesville, FL, USA; Dental Materials Division, Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil
| | - Stefany Pontes
- Center of Dental Biomaterials, Department of Restorative Dental Science, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Mateus Garcia Rocha
- Center of Dental Biomaterials, Department of Restorative Dental Science, College of Dentistry, University of Florida, Gainesville, FL, USA
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Burgo TL, Pereira GKR, Iglesias BA, Moreira KS, Valandro LF. AFM advanced modes for dental and biomedical applications. J Mech Behav Biomed Mater 2022; 136:105475. [PMID: 36195052 DOI: 10.1016/j.jmbbm.2022.105475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/15/2022] [Accepted: 09/18/2022] [Indexed: 11/18/2022]
Abstract
Several analytical methods have been employed to elucidate bonding mechanisms between dental hard tissues, luting agents and restorative materials. Atomic Force Microscopy (AFM) imaging that has been extensively used in materials science, but its full capabilities are poorly explored by dental research community. In fact, commonly used to obtain topographic images of different surfaces, it turns out that AFM is an underestimated technique considering that there are dozens of basic and advanced modes that are scarcely used to explain properties of biomaterials. Thus, this paper addresses the use of phase-contrast imaging, force-distance curves, nanomechanical and Kelvin probe force techniques during AFM analysis to explore topological, nanomechanical and electrical properties of Y-TZP samples modified by different surface treatments, which has been widely used to promote adhesive enhancements to such substrate. The AFM methods are capable of access erstwhile inaccessible properties of Y-TZP which allowed us to describe its adhesive properties correctly. Thus, AFM technique emerges as a key tool to investigate the complex nature of biomaterials and highlighting its inherent interdisciplinarity that can be successfully used for bridging fragmented disciplines such as solid-state physics, microbiology and dental sciences.
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Affiliation(s)
- ThiagoA L Burgo
- Department of Chemistry and Environmental Sciences, Ibilce, São Paulo State University (Unesp), São Jose do Rio Preto, São Paulo State, Brazil.
| | - Gabriel Kalil Rocha Pereira
- MSciD and Ph.D. Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Bernardo Almeida Iglesias
- Department of Chemistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Kelly S Moreira
- Department of Chemistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Luiz Felipe Valandro
- MSciD and Ph.D. Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
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Guilardi LF, Pereira G, Giordani JC, Kleverlaan CJ, Valandro LF, Rippe MP. Cement Choice and the Fatigue Performance of Monolithic Zirconia Restorations. Oper Dent 2022; 47:461-472. [PMID: 35917240 DOI: 10.2341/20-143-l] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2021] [Indexed: 11/23/2022]
Abstract
This study investigated the fatigue failure load of simplified monolithic yttria partially stabilized zirconia polycrystal restorations cemented to a dentin-like substrate using different luting systems. Disc-shaped ceramic (Zenostar T, 10 mm Ø × 0.7 mm thick) and dentin-like substrate (10 mm Ø × 2.8 mm thick) were produced and randomly allocated into eight groups, without or with thermocycling (TC=5-55°C/12,000×): "cement" (RelyX Luting 2 - glass ionomer cement [Ion], [Ion/TC]; RelyX U200 - self-adhesive resin cement [Self], [Self/TC]; Single Bond Universal+RelyX Ultimate - MDP-containing adhesive + resin cement [MDPAD + RC], [MDP-AD + RC/TC]; ED Primer II+Panavia F 2.0 - Primer + MDP-containing resin cement [PR + MDP-RC], [PR + MDP-RC/TC])). Each luting system was used as recommended by the manufacturer. Staircase methodology (20 Hz; 250,000 cycles) was applied for obtaining the fatigue failure loads. Fractographic characteristics were also assessed. At baseline, the Ion group presented the lowest fatigue load, although it was statistically similar to the Self group. The resin-based cement systems presented the highest fatigue performance, with the Ion group being only statistically equal to the Self group. Thermocycling influenced the groups differently. After aging, the MDP-AD + RC presented the highest mean, followed by the PR + MDP-RC and Self groups, while the Ion group had the lowest mean. Fractographic analysis depicted all failures as radial cracks starting at the zirconia intaglio surface. The luting system with MDP-containing adhesive applied prior to the resin cement presented the highest fatigue failure load after aging, presenting the best predictability of stable performance. Despite this, monolithic zirconia presents high load-bearing capability regardless of the luting agent.
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Affiliation(s)
- L F Guilardi
- Luis Felipe Guilardi, associate researcher, Post-Graduate Program in Oral Science (Prosthodontics Unit), Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil
| | - Gkr Pereira
- Gabriel Kalil Rocha Pereira, MsciD, PhD, adjunct professor, Post-Graduate Program in Oral Science (Prosthodontics Units), Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil
| | - J C Giordani
- João Carlos Giordani, undergraduate student, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil
| | - C J Kleverlaan
- Cornelis Johannes Kleverlaan, PhD, full professor, Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam, Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, Noord-Holland, The Netherlands
| | - L F Valandro
- Luiz Felipe Valandro, MSciD, PhD, full professor, Post-Graduate Program in Oral Science (Prosthodontics Units), Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil
| | - M P Rippe
- *Marilia Pivetta Rippe, MSciD, PhD, adjunct professor, Post-Graduate Program in Oral Science (Prosthodontics Units), Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil
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Prado PHCO, Dapieve KS, Campos TMB, Valandro LF, Melo RMD. Effect of hydrothermal and mechanical aging on the fatigue performance of high-translucency zirconias. Dent Mater 2022; 38:1060-1071. [DOI: 10.1016/j.dental.2022.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 02/10/2022] [Accepted: 04/01/2022] [Indexed: 11/03/2022]
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Bayat M, Adibi H, Barzegar A, Rezaei SM. Experimental and numerical investigation of heat generation and surface integrity of ZrO2 bioceramics in grinding process under MQL condition. J Mech Behav Biomed Mater 2022; 131:105226. [DOI: 10.1016/j.jmbbm.2022.105226] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 03/30/2022] [Accepted: 04/02/2022] [Indexed: 11/25/2022]
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Hajhamid B, Alfrisany N, Somogyi-Ganss E. The effect of accelerated aging on crystalline structures and optical properties of different monolithic zirconia: A qualitative systematic review. Dent Mater 2022; 38:569-586. [DOI: 10.1016/j.dental.2022.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 02/14/2022] [Indexed: 11/03/2022]
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Costa SO, Lima SNL, Nassif MV, Millan Cardenas AF, Tavarez RRDJ, Lima DM, Bandeca MC. Evaluation of the Bond Strength of Densely Sintered Ceramics Subjected to Extended Firing. Clin Cosmet Investig Dent 2021; 13:371-377. [PMID: 34512033 PMCID: PMC8420077 DOI: 10.2147/ccide.s247610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/01/2020] [Indexed: 11/23/2022] Open
Abstract
Introduction Critical failures in ceramic materials can be caused by the processing mode, which includes all steps taken in the manufacture of a ceramic part, from molding to firing. Purpose To evaluate the effect of extended firing on bond strength in densely sintered ceramics of the zirconium reinforced lithium silicate, lithium disilicate, and feldspathic ceramic. Materials and Methods Three types of ceramics were evaluated: zirconium reinforced lithium silicate, lithium disilicate, feldspathic ceramic. A total of 6 ceramic blocks, two for each material were used in the study. Each block was cut into four square sections. A total of 24 ceramic surfaces were randomly distributed into 6 groups (n = 4 surfaces per group) divided according to the variables: heat treatment: conventional firing or extended firing; test time: immediate (24 hours after cementation) or longevity (after 1000 cycles of thermocycling). The bond strength tests were performed in a semi-universal test machine for microshear bond strength. For data analysis, the Shapiro-Wilk test was performed to evaluate the normality between the groups measured, and regarding homoscedasticity (homogeneity of variances) by the Bartlett test. The comparisons between the groups were made using the nonparametric Kruskal-Wallis test. Results There was no statistically significant difference of the resistance values in relation to the thermal treatment methods (conventional firing and extended firing) in any ceramic group (p <0.05). Among the times (immediate and long), there was a statistically significant difference (p <0.05), with higher resistance values for immediate time. Conclusion Extended firing did not influence the micro-shear bond strength of zirconium reinforced lithium silicate, lithium disilicate, feldspathic ceramic.
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Affiliation(s)
- Samuel Oliveira Costa
- Post-Graduation Program in Dentistry, CEUMA University, São Luis, Maranhão, 65075-120, Brazil
| | | | - Maria Victória Nassif
- Post-Graduation Program in Dentistry, University of Tuiuti of Paraná, Curitiba, 82010-330, Brazil
| | | | | | - Darlon Martins Lima
- Post-Graduation Program in Dentistry, Federal University of Maranhão, São Luis, Maranhão, Brazil
| | - Matheus Coelho Bandeca
- Post-Graduation Program in Dentistry, University of Tuiuti of Paraná, Curitiba, 82010-330, Brazil.,Post-Graduation Program in Dentistry, Federal University of Maranhão, São Luis, Maranhão, Brazil
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Durkan R, Deste Gökay G, Şimşek H, Yilmaz B. Biaxial flexural strength and phase transformation characteristics of dental monolithic zirconia ceramics with different sintering durations: An in vitro study. J Prosthet Dent 2021; 128:498-504. [PMID: 34059297 DOI: 10.1016/j.prosdent.2021.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 04/02/2021] [Accepted: 04/02/2021] [Indexed: 11/29/2022]
Abstract
STATEMENT OF PROBLEM Zirconia is a polymorphic metastable material which can react through a phase transformation from tetragonal to monoclinic when exposed to mechanical, physical, or chemical stimuli. PURPOSE The purpose of this in vitro study was to investigate the fracture strength and phase structure of different high-translucency zirconia ceramics depending on the changes in sintering duration and thermocycling. MATERIAL AND METHODS Two monolithic zirconia ceramics, Katana (KAT) and NexxZr (NEX), were used to prepare disk-shaped specimens (n=66). The sintering temperature was 1500 °C, and 3 different sintering durations were tested: 1 hour, 2 hours (recommended by the manufacturer), and 3 hours. Thermocycling was applied to half the specimens. Fracture strength was calculated, and the specimens were analyzed with an X-ray diffractometer (XRD) to determine the level of the phase transformation. The normal distribution of the data was analyzed by using the Shapiro-Wilk test. Two-way ANOVA was used to compare multiple groups (α=.05). The Fisher least significant difference test was applied to identify significant differences in fracture strength. The paired-specimen t test was applied to perform intragroup comparisons. RESULTS Sintering duration significantly affected the fracture strength of KAT (P=.007). For nonthermocycled specimens, the fracture strength of NEX was significantly higher than that of KAT (P<.001). Thermocycling had a significant effect on fracture strength depending on sintering duration and zirconia ceramic interaction (P=.046). CONCLUSIONS The sintering duration only affected the KAT zirconia, and the fracture strength of KAT decreased when sintered for 3 hours. Thermocycling decreased the fracture strength of both zirconias, except when the sintering duration was 2 hours for NEX. The fracture strength was higher for NEX than for KAT. Tetragonal-monoclinic phase transformation was not found for either zirconia according to the XRD analysis.
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Affiliation(s)
- Rukiye Durkan
- Associate Professor, Department of Prosthodontics, Faculty of Dentistry, Afyonkarahisar Health Sciences University, Afyonkarahisar, Turkey
| | - Gonca Deste Gökay
- Asisstant Professor, Department of Prosthodontics, Faculty of Dentistry, Bursa Uludağ University, Bursa, Turkey.
| | | | - Burak Yilmaz
- Associate Professor, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland; Department of Restorative, Preventive and Pediatric Dentistry, School of Dental Medicine, University of Bern, Bern, Switzerland; Adjunct Professor, Division of Restorative and Prosthetic Dentistry, The Ohio State University, Columbus, Ohio
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11
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Saker S, Özcan M. Marginal discrepancy and load to fracture of monolithic zirconia laminate veneers: The effect of preparation design and sintering protocol. Dent Mater J 2020; 40:331-338. [PMID: 33162456 DOI: 10.4012/dmj.2020-007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To investigate and analyze the impact of teeth preparation designs and sintering protocol on marginal fit and fracture resistance of monolithic translucent zirconia laminate veneers. A total of 40 extracted intact human maxillary central incisors were assigned into 4 groups (n=10/each group) to investigate 2 variables: (1) the design of tooth preparation (a 1.5 mm incisal reduction with or without palatal chamfer) and (2) the two different sintering programs used for translucent zirconia restoration (standard or speed sintering procedure). Marginal discrepancy was evaluated using a digital microscope. The specimens were loaded to failure in the compression mode, using a universal testing machine with a crosshead speed of 0.5 mm/min. Marginal adaptation of monolithic translucent zirconia laminates are affected by both tooth preparation design and sintering protocol. However, resistance to fracture of translucent zirconia laminates has affected mainly by sintering procedure regardless the teeth preparation design used.
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Affiliation(s)
- Samah Saker
- Fixed Prosthodontics Department, Faculty of Dentistry, Mansoura University
| | - Mutlu Özcan
- Devision of Dental Biomaterials Unit, Center for Dental and Oral Medicine, Clinic for Reconstructive Dentistry
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Monolithic and Minimally Veneered Zirconia Complications as Implant-Supported Restorative Material: A Retrospective Clinical Study up to 5 Years. BIOMED RESEARCH INTERNATIONAL 2020; 2020:8821068. [PMID: 33134389 PMCID: PMC7593719 DOI: 10.1155/2020/8821068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/01/2020] [Accepted: 10/07/2020] [Indexed: 11/30/2022]
Abstract
Objective Long-term clinical data on the success and complication rates of monolithic or minimally veneered zirconia implant-supported restorations are lacking. Hence, the purpose of this retrospective clinical study was to analyze the complications of monolithic or partially veneered zirconia implant-supported restorations up to 5 years follow-up. Material and Methods. Single crowns, bridges, and full-arch rehabilitations were included. The selection process was achieved by reviewing data from the prosthetic laboratory and excluding cases in which zirconium and full-ceramic coating restorations were used. A total of 154 restorations were included (82 monolithic and 72 with buccal ceramic stratification). All the complications encountered, and the solutions applied, were explained. Results A total of 93 restorative units had a follow-up of between 24 and 60 months, and 61 restoration units had a follow-up of between 12 and 24 months. A total of 7 complications were encountered (14.58% of cases; 95.45% per prosthetic unit). The technical complication rate was 2.08% (one case of minor chipping in one prosthetic unit); regarding the mechanical complications, four decementations (8.33% of the cases) and two screw loosening (4.17% of the cases) were encountered. Conclusions Considering the limitations of this study, it can be concluded that monolithic or partially veneered zirconia implant-supported restorations have a good clinical behavior during a follow-up period of up to 5 years.
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Roulet JF, Schepker KL, Truco A, Schwarz HC, Rocha MG. Biaxial flexural strength, crystalline structure, and grain size of new commercially available zirconia-based ceramics for dental appliances produced using a new slip-casting method. J Mech Behav Biomed Mater 2020; 114:104180. [PMID: 33158788 DOI: 10.1016/j.jmbbm.2020.104180] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/20/2020] [Accepted: 10/23/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The aim of this study was to evaluate the biaxial flexural strength, the crystalline structure, and the grain size of zirconia-based ceramics produced using a new slip-casting method. MATERIALS AND METHODS Yttria-stabilized Tetragonal Zirconia Polycrystal (Y-TZP) and Alumina Toughened Zirconia (ATZ) ceramics were purchased from different manufactures. For the experimental group, ceramics produced using a patent pending slip-casting method (Slurry, Decema GmbH) was used. Slurry ceramics (n = 42) with a diameter of 14 ± 0.2 mm were produced by a proprietary colloidal shaping process, sintered, and subsequently polished with a lapping process using 15 μm diamond particles to a thickness of 1.2 ± 0.2 mm. For the control group, ceramics produced using the hot isostatic pressure method (HIP, Metoxit AG) were used. HIP ceramics discs (n = 42) with a diameter of 15.5 ± 0.02 mm were produced by classical HIP method and subsequently machined to a thickness of 1.99 ± 0.04 mm 32 discs of each ceramic were submitted to a biaxial flexural strength test using an universal testing machine at a crosshead speed of 0.5 mm/min. Statistical analyses using two-way ANOVA and Weibull distribution were performed. 2 discs of each ceramic were analyzed using X-ray diffraction for grain crystalline phase quantification. 2 discs of each ceramic were thermally etched and scanning electron microscopy images were obtained for grain size analysis (ISO 13383-1:2012). 6 discs of each ceramic were used for density measurement using the Archimedes' method. RESULTS For both ATZ and Y-TZP ceramics, the biaxial flexural strength and the characteristic strength of ceramics produced using the Slurry method were significantly higher than ones of the ceramic produced using HIP. The structure analysis confirmed the superiority of the Slurry ceramics which had only 1.2% tetragonal phase compared to 11-16% for the HIP ceramics. Grain size distributions covered a wide range 50-800 nm; the ZrO2 grains of the Slurry ceramics were significantly smaller than the ones of the control ceramics, while the Al2O3 grain distributions were not affected by the manufacturing process. The manufacturing process had no influence on the density of both materials. CONCLUSIONS The Slurry method using a new proprietary slip-casting method to produce Y-TZP and ATZ dental ceramics presented higher biaxial flexural strength, less monoclinic phase and smaller ZrO2 grains.
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Affiliation(s)
- Jean-François Roulet
- University of Florida, Center of Dental Biomaterials, Department of Restorative Dental Science, College of Dentistry, Room D9-26, 1395 Center Drive, Gainesville, FL, 32610-0415, USA.
| | - Kristy Lee Schepker
- Research Service Center, Herbert Wertheim College of Engineering, University of Florida, PO BOX 116621, Gainesville, FL, 32611- 0001, USA
| | - Andres Truco
- Research Service Center, Herbert Wertheim College of Engineering, University of Florida, PO BOX 116621, Gainesville, FL, 32611- 0001, USA
| | | | - Mateus Garcia Rocha
- University of Florida, Center of Dental Biomaterials, Department of Restorative Dental Science, College of Dentistry, Room D9-26, 1395 Center Drive, Gainesville, FL, 32610-0415, USA
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Fiorin L, Moris ICM, Faria ACL, Ribeiro RF, Rodrigues RCS. Effect of different grinding protocols on surface characteristics and fatigue behavior of yttria-stabilized zirconia polycrystalline: An in vitro study. J Prosthet Dent 2020; 124:486.e1-486.e8. [PMID: 32446636 DOI: 10.1016/j.prosdent.2020.03.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 11/17/2022]
Abstract
STATEMENT OF PROBLEM Zirconia frameworks milled by computer-aided design and computer-aided manufacturing (CAD-CAM) often require clinical adjustments. In addition, zirconia prefabricated abutments can also require customization to achieve an adequate emergence profile. However, the influence of grinding adjustment on the surface characteristics and mechanical behavior of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and the best grinding protocol is unclear. PURPOSE The purpose of this in vitro study was to evaluate the effect of different grinding protocols on the surface characteristics, phase transformation, and mechanical behavior of Y-TZP for frameworks and implant abutments. MATERIAL AND METHODS Bar-shaped specimens were fabricated according to ISO 6872-2016 and divided into 3 groups: GC (control, untreated), GA (grinding and finishing with medium and fine diamond rotary instruments using high-speed handpiece under constant water cooling), and GB (grinding and finishing with coarse and medium diamond rotary instruments, respectively, using slow-speed handpiece without water cooling). After specimen grinding, the topography and surface roughness were evaluated by using a laser confocal microscope, the Young modulus was measured by the impulse excitation technique, and crystallographic phase transformation was analyzed by X-ray diffraction. Specimens were then submitted to step-stress accelerated life testing (n=18). The surface roughness and Young modulus results were analyzed by 1-way ANOVA and the Tukey honestly significant difference test (α=.05). The data of step-stress accelerated life testing were analyzed by the survival probability considering the number of cycles and force until fracture. RESULTS Statistically significant differences were found among groups considering surface roughness (GA>GB>GC) (P<.05) and Young modulus (GB>GA=GC) (P=.003). X-ray diffraction showed that grinding leads to phase transformation, GC showed only tetragonal phase, while GA and GB showed tetragonal and monoclinic phases. No statistically significant difference (P<.05) was found among groups submitted to the same loading profile when the survival probability was compared, but significant difference was found between the light and moderate loading (P=.002) and light and severe loading (P=.014) of GB when different loading profiles in each group were compared. CONCLUSIONS Although grinding protocols affected surface characteristics and promoted phase transformation, the mechanical behavior of Y-TZP was not impaired. Therefore, both the grinding protocols tested can be safely used based on the evaluated properties.
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Affiliation(s)
- Lívia Fiorin
- Graduate student, Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil
| | - Izabela C M Moris
- Former graduate, Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil
| | - Adriana C L Faria
- Laboratory specialist, Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil
| | - Ricardo F Ribeiro
- Professor, Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil
| | - Renata C S Rodrigues
- Professor, Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil.
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Miranda JS, Barcellos ASDP, Campos TMB, Cesar PF, Amaral M, Kimpara ET. Effect of repeated firings and staining on the mechanical behavior and composition of lithium disilicate. Dent Mater 2020; 36:e149-e157. [PMID: 32061444 DOI: 10.1016/j.dental.2020.02.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 09/02/2019] [Accepted: 02/04/2020] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To evaluate the composition, flexural strength and fatigue behaviour of lithium disilicate ceramic (LD) after repeated firings and different staining techniques. METHODS LD discs were fabricated and divided according to number of firing cycles and staining technique: CO - control, discs were crystallized (850°C/10min); SC - single-step characterization - crystallization and staining (applied with a thin brush) were performed in a single step with one firing cycle (850°C/10min); and DC - double-step characterization - crystallization firing cycle was performed first (850°C/10min), followed by staining firing cycle (770°C/90s). Specimens were fired two, four or six times (one crystallization firing cycle and one, three or five staining firing cycles), resulting into 9 groups (n=30): COII, COIV, COVI, SCII, SCIV, SCVI, DCII, DCIV and DCVI. The composition of the specimens was investigated (EDS, XRD, Raman spectroscopy), and the biaxial flexural strength (n=10) and staircase tests (n=20, 5×104 cycles, 5Hz) were performed. Data were subjected to one-way ANOVA and Tukey's test (α=0.05). RESULTS EDS and XRD revealed amorphous content for stained groups. Biaxial flexural strength was not affected by repeated firings in any group, but stained groups presented lower flexural strength than control groups (p=0.001). The fatigue limit results decreased in all groups compared to flexural strength. SC groups showed similar (SCII and SCIV) or even higher fatigue limits (SCVI) than the control groups, and DC showed the lowest fatigue limit values. SEM and Raman suggested that the interfaces between staining and the LD showed only an overlap for the DC groups, whereas for the SC it was suggested an interaction between the stain and the LD. SIGNIFICANCE Repeated firings did not result in decreased lithium disilicate flexural strength.Staining affected flexural strength and also resulted in increased amorphous content in the characterized specimens. Single-step staining resulted in the highest fatigue limit.
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Affiliation(s)
- Jean Soares Miranda
- Institute of Science and Technology, UNESP - Paulista State University, São José dos Campos, São Paulo, Brazil
| | | | | | | | - Marina Amaral
- Department of Dentistry, University of Taubaté, Taubaté, São Paulo, Brazil
| | - Estevão Tomomitsu Kimpara
- Institute of Science and Technology, UNESP - Paulista State University, São José dos Campos, São Paulo, Brazil.
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da Rocha JFSS, de Avila ED, Rigolin MSM, Barbugli PA, Marin DOM, Mollo Junior FA, Jorge JH. Biological and physicochemical implications of the aging process on titanium and zirconia implant material surfaces. J Prosthet Dent 2020; 125:165-174. [PMID: 32037296 DOI: 10.1016/j.prosdent.2019.11.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 11/08/2019] [Accepted: 11/08/2019] [Indexed: 12/25/2022]
Abstract
STATEMENT OF PROBLEM Changes in physicochemical properties because of implant material aging and natural deterioration in the oral environment can facilitate microbial colonization and disturb the soft-tissue seal between the implant surfaces. PURPOSE The purpose of this in vitro study was to investigate the effect of aging time on the physicochemical profile of titanium (Ti) and zirconia (ZrO2) implant materials. Further microbiology and cell analyses were used to provide insights into the physicochemical implications of biological behavior. MATERIAL AND METHODS Disk-shaped specimens of Ti and ZrO2 were submitted to roughness, morphology, and surface free energy (SFE) analyses before nonaging (NA) and after the aging process (A). To simulate natural aging, disks were subjected to low-temperature degradation (LTD) by using an autoclave at 134 ºC and 0.2 MPa pressure for 20 hours. The biological activities of the Ti and ZrO2 surfaces were determined by analyzing Candida albicans (C. albicans) biofilms and human gingival fibroblast (HGF) cell proliferation. For the microbiology assays, a variance analysis method (ANOVA) was used with the Tukey post hoc test. For the evaluation of cellular proliferation, the Kruskal-Wallis test followed by Dunn multiple comparisons were used. RESULTS Ti nonaging (TNA) and ZrO2 nonaging (ZNA) disks displayed hydrophilic and lipophilic properties, and this effect was sustained after the aging process. Low-temperature degradation resulted in a modest change in intermolecular interaction, with 1.06-fold for TA and 1.10-fold for ZA. No difference in biofilm formation was observed between NA and A disks of the same material. After 48 hours, the viability of the attached HGF cells was very similar to that in the NA and A groups, regardless of the tested material. CONCLUSION The changes in the physicochemical properties of Ti and ZrO2 induced by the aging process do not interfere with C. albicans biofilm formation and HGF cell attachment, even after long-term exposure.
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Affiliation(s)
- José Francisco S S da Rocha
- Masters graduate, Department of Dental Materials and Prosthodontics, School of Dentistry at Araraquara, São Paulo State University (UNESP), Araraquara, Brazil
| | - Erica D de Avila
- Postdoctoral Research Fellow, Department of Dental Materials and Prosthodontics, School of Dentistry at Araraquara, São Paulo State University (UNESP), Araraquara, Brazil.
| | - Maria Sílvia M Rigolin
- Postdoctoral Research Fellow, Department of Dental Materials and Prosthodontics, School of Dentistry at Araraquara, São Paulo State University (UNESP), Araraquara, Brazil
| | - Paula A Barbugli
- Technical Assistant, Department of Dental Materials and Prosthodontics, School of Dentistry at Araraquara, São Paulo State University (UNESP), Araraquara, Brazil
| | - Danny O M Marin
- Assistant Professor, Department of Dentistry, Federal University of Santa Catarina (UFSC), Florianópolis, Brazil
| | - Francisco A Mollo Junior
- Associate Professor, Department of Dental Materials and Prosthodontics, School of Dentistry at Araraquara, São Paulo State University (UNESP), Araraquara, Brazil
| | - Janaina H Jorge
- Associate Professor, Department of Dental Materials and Prosthodontics, School of Dentistry at Araraquara, São Paulo State University (UNESP), Araraquara, Brazil
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Prado PHCO, Monteiro JB, Campos TMB, Thim GP, de Melo RM. Degradation kinetics of high-translucency dental zirconias: Mechanical properties and in-depth analysis of phase transformation. J Mech Behav Biomed Mater 2020; 102:103482. [DOI: 10.1016/j.jmbbm.2019.103482] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/09/2019] [Accepted: 10/09/2019] [Indexed: 10/25/2022]
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Vila-Nova TEL, Gurgel de Carvalho IH, Moura DMD, Batista AUD, Zhang Y, Paskocimas CA, Bottino MA, de Assunção E Souza RO. Effect of finishing/polishing techniques and low temperature degradation on the surface topography, phase transformation and flexural strength of ultra-translucent ZrO 2 ceramic. Dent Mater 2020; 36:e126-e139. [PMID: 32008750 DOI: 10.1016/j.dental.2020.01.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/24/2019] [Accepted: 01/14/2020] [Indexed: 01/25/2023]
Abstract
OBJECTIVE To investigate the effect of different surface finishing and polishing regimes and low temperature degradation on flexural strength, phase transformation and surface topography of ultra-translucent ZrO2 ceramic. METHODS 300 (n=15/group) of conventional zirconia (Z: Ice Zirkon Transluzent) and ultra-translucent zirconia (UT: Prettau Anterior) bar-specimens were made and divided according to the "Finishing/Polishing" - (C - Control, B - diamond rubber polishers, P - adjusting with burs, PB - adjusting with burs+diamond polishers, PG - adjusting with burs+glaze), "Low temperature Degradation (LTD)" (with or without a treatment at 127°C, 1.7bar/24h). Then, a 3-point mini flexural test was performed in a universal testing machine (1mm/min, 500kgf load cell). SEM, EDS, XDR, AFM, optical profilometry and Weibull analysis were performed. Data were analyzed by 3-way ANOVA and Tukey's post-test (5%). RESULTS Groups ZPBD (1670±253MPa), ZBD (1664±217MPa), and ZB (1655±3678MPa) showed significantly higher flexural strength than the UTPG group (372±56MPa). The Weibull modulus was significantly higher for the ZPD group compared to the UB, UCD, UPD and UPBD, while UTB, UTCD and UTPD had the lowest value. Monoclinic phases were observed only in the conventional zirconia groups and were more evident after LTD. Diamond rubber polishers presented less roughness for both zirconias. SIGNIFICANCE The use of diamond rubber polishers is the most suitable finishing/polishing method for zirconia ceramic restorations and that final glazing reduces the fracture resistance of these materials.
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Affiliation(s)
- Taciana Emília Leite Vila-Nova
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, CEP: 59056-000, Brazil.
| | - Isabelle Helena Gurgel de Carvalho
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Division of Prosthodontics, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, 59056-000, Brazil.
| | - Dayanne Monielle Duarte Moura
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Division of Prosthodontics, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, 59056-000, Brazil.
| | - André Ulisses Dantas Batista
- Federal University of Paraíba (UFPB), Department of Restorative Dentistry, Conj. Pres. Castelo Branco III, João Pessoa, PB, 58033-455, Brazil.
| | - Yu Zhang
- New York University College of Dentistry, Department of Biomaterials and Biomimetics, 433 First Avenue, Room 810, New York, NY, 10010, United States.
| | - Carlos Alberto Paskocimas
- Federal University of Rio Grande do Norte (UFRN), Department of Material Engineering, Av. Salgado Filho, 3000, Lagoa Nova, Natal, RN, Brazil.
| | - Marco Antonio Bottino
- São Paulo State University (UNESP), Institute of Science and Technology, Av Engenheiro Francisco José Longo, 777, Jardim São Dimas, São José dos Campos, São Paulo, São José dos Campos, CEP: 12245-000, Brazil.
| | - Rodrigo Othávio de Assunção E Souza
- Adjunct Professor at Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Division of Prosthodontics, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, 59056-000, Brazil.
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Moqbel NM, Al-Akhali M, Wille S, Kern M. Influence of Aging on Biaxial Flexural Strength and Hardness of Translucent 3Y-TZP. MATERIALS 2019; 13:ma13010027. [PMID: 31861613 PMCID: PMC6981501 DOI: 10.3390/ma13010027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/02/2019] [Accepted: 12/13/2019] [Indexed: 11/16/2022]
Abstract
The purpose of this research was to evaluate the influence of aging and surface treatment on surface roughness, biaxial flexural strength (BFS), and Vickers hardness (VHN) of translucent dental zirconia. Half of 80 disc-shaped zirconia specimens (1.2 mm thickness and 12 mm diameter) were aged (group A) in an autoclave for 20 h (134 °C and 0.2 MPa) and the other half were not aged (group N). Specimens were subjected to: no surface treatment (SIN), particle air-abrasion with 50 µm alumina particles at 1 bar (0.1 MPa) and 2.5 bar (0.25 MPa), or polishing down to 1 µm (POL). Specimens were analyzed using X-ray diffraction, laser scanning microscope, BFS, and VHN tests. Three groups (N-SIN, N-POL, and A-POL) showed almost no monoclinic phase. While other groups showed monoclinic phase ratios ranging from 7.5 vol. % ± 2.4 vol. % (N-0.1 MPa) to 41.5 vol. % ± 0.3 vol. % (A-0.1 MPa). Aging and particle air-abrasion increased significantly the BFS, ranging from 720 ± 37 MPa (N-SIN) to 1153 ± 92 MPa (N-0.1 MPa). The hardness was not influenced significantly by aging. A certain amount of monoclinic phase at the surface strengthens the high translucent dental zirconia, while hardness and roughness are not influenced. The pressure of particle air-abrasion showed no influence on the evaluated properties.
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Affiliation(s)
- Nawal M. Moqbel
- Correspondence: ; Tel.: +49-0431-500-264-10; Fax: +49-0431-500-264-04
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Aliaga R, Miotto LN, Candido LM, Fais L, Pinelli L. Does Diamond Stone Grinding Change the Surface Characteristics and Flexural Strength of Monolithic Zirconia? Oper Dent 2019; 45:318-326. [PMID: 31794343 DOI: 10.2341/19-023-l] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
PURPOSE The present study evaluated the effect of grinding on the surface morphology, mean roughness, crystalline phase, flexural strength, and Weibull modulus of monolithic (MZ) and conventional (CZ) zirconias. METHODS AND MATERIALS CZ and MZ bars and square-shaped specimens were distributed into three subgroups, combining grinding (G) and irrigation (W) with distilled water: Ctrl (Control: no grinding, 20 × 4 × 1.2 mm and 12 × 1.2 mm), DG (dry grinding, 20 × 4 × 1.5 mm and 12 × 1.5 mm), and WG (grinding with irrigation, 20 × 4 × 1.5 mm and 12 × 1.5 mm). The grinding (0.3 mm) was performed on a standardized device using a low-rotation wheel-shaped diamond stone. The four-point flexural strength test was performed on the EMIC 2000 machine (5 KN, 0.5 mm/min). Scanning electron microscopy (SEM) was used to evaluate the surface morphology. An X-ray diffractometer (XRD) was used to obtain the crystalline structures that were analyzed by the Rietveld method. Flexural strength (FS) values were subjected to the Shapiro-Wilk test and two-way analysis of variance followed by the Tukey's test (for all tests, α=0.05). RESULTS Grinding, either with or without irrigation, did not change the FS of the MZ but increased the FS of the CZ. Both MZ and CZ showed similar morphologic patterns after grinding, and in the WG groups, the grinding was more aggressive. The MZ had greater monoclinic content in all groups; grinding without irrigation caused the smallest t→m transformation. CONCLUSION The grinding, when necessary, should be carried out without irrigation for conventional and monolithic zirconias.
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Guilardi LF, Pereira GKR, Giordani JC, Kleverlaan CJ, Valandro LF, Rippe MP. Effect of zirconia surface treatment, resin cement and aging on the load-bearing capacity under fatigue of thin simplified full-contour Y-TZP restorations. J Mech Behav Biomed Mater 2019; 97:21-29. [DOI: 10.1016/j.jmbbm.2019.04.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 04/24/2019] [Accepted: 04/26/2019] [Indexed: 10/26/2022]
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Zucuni CP, Pereira GKR, Dapieve KS, Rippe MP, Bottino MC, Valandro LF. Low-fusing porcelain glaze application does not damage the fatigue strength of Y-TZP. J Mech Behav Biomed Mater 2019; 99:198-205. [PMID: 31374515 DOI: 10.1016/j.jmbbm.2019.07.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 07/10/2019] [Accepted: 07/20/2019] [Indexed: 02/04/2023]
Abstract
This study evaluated and compared the effects of two glaze application methods (brush and spray) on the fatigue strength and surface characteristics (topography and roughness) of a translucent yttrium stabilized partially tetragonal zirconia polycrystal ceramic (Y-TZP) prior to and after grinding. Disc-shaped specimens of translucent Y-TZP (Vita YZ-HT; Vita-Zahnfabrik) were processed (ISO 6872-2015) and randomly allocated into 6 groups, according to the surface treatments performed on the tensile surface: Ctrl - as-sintered (no treatment); Gr - grinding with a diamond bur (181 μm-grit; #3101G); Br - glaze obtained from a powder-liquid mix and applied by brush (Vita Akzent; Vita Zahnfabrik); Sp - glaze application via spray (Vita Akzent Plus; Vita Zahnfabrik); Gr + Br and Gr + Sp - association of grinding + respective glaze method. Analyses of surface roughness (Ra and Rz), fatigue strength (staircase method), surface topography and fractography were carried out. The as-sintered condition had the smoothest surface, while grinding led to the rougher and more heterogeneous topography. Both glaze application methods showed a potential for topography evenness (smoothening effect), while the glaze spray method led to thinner layers of material, showing a limitation in reducing the roughness compared to the brush method. No deleterious effect on fatigue strength of the Y-TZP could be observed, as the glaze-spray application on the as-sintered surface showed the highest values. Fractography depicted two distinct fracture origin regions: from defects in the surface/sub-surface region for the Ctrl and Gr groups; and at the zirconia-glaze layer interface for Br, Sp, Gr + Br and Gr + Sp. The clinical relevance of this work is that the tested glaze application methods did not damage the fatigue strength of the tested Y-TZP.
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Affiliation(s)
- Camila Pauleski Zucuni
- MSciD and PhD Post-graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
| | - Gabriel Kalil Rocha Pereira
- MSciD Post-graduate Program in Dentistry, School of Dentistry, Meridional Faculty - IMED, Passo Fundo, Rio Grande do Sul, Brazil.
| | - Kiara Serafini Dapieve
- MSciD and PhD Post-graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
| | - Marilia Pivetta Rippe
- MSciD and PhD Post-graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
| | - Marco Cícero Bottino
- School of Dentistry, Dept. of Cariology, Restorative Sciences, Endodontics, University of Michigan, Ann Arbor, USA.
| | - Luiz Felipe Valandro
- MSciD and PhD Post-graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
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Zucuni CP, Guilardi LF, Rippe MP, Pereira GKR, Valandro LF. Polishing of Ground Y-TZP Ceramic is Mandatory for Improving the Mechanical Behavior. Braz Dent J 2019; 29:483-491. [PMID: 30517448 DOI: 10.1590/0103-6440201802044] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/27/2018] [Indexed: 11/22/2022] Open
Abstract
It evaluated the effect of aging by Low Temperature Degradation (LTD), executed after post- processing surface treatments (polishing, heat treatment and glazing), on the surface characteristics (micromorphology and roughness) and on the structural stability (phase transformation and mechanical behavior-flexural strength and structural reliability) of a ground yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic. Discs of Y-TZP (VITA In-Ceram YZ) were manufactured (ISO:6872-2015; 15 mm in diameter and 1.2 ± 0.2 mm in thickness) and randomly assigned into 10 groups according two factors: "aging" in 2 levels (with or without) and "surface treatment" in 5 levels (Ctrl: as-sintered; Gr: grinding with coarse diamond bur; Gr + HT: grinding plus heat treatment; Gr + Pol: grinding plus polishing; Gr + Gl: grinding plus glazing). Roughness (n=30), biaxial flexural test (n=30), phase transformation (n=2), and surface topography (n=2) analyses were performed. Aging led to an intense increase in monoclinic (m) phase content for all the tested conditions, being the as-sintered samples (Ctrl= 65.6%) more susceptible to the t-m phase transformation. Despite of increasing the m-phase content, aging was not detrimental for characteristic strength (except to the grinding condition). There was no significant reduction in the Weibull modulus after surface treatments. Additionally, heat treatment and glazing after grinding led to a decrease in characteristic strength, while polishing presented the highest characteristic strength values. Thus, polishing is mandatory after grinding the Y-TZP ceramic, while performing glazing or heat-treatment alone after grinding lead to the worst mechanical performance.
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Affiliation(s)
- Camila Pauleski Zucuni
- Graduate Program in Oral Science, Prosthodontics Units, UFSM - Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Luis Felipe Guilardi
- Graduate Program in Oral Science, Prosthodontics Units, UFSM - Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.,Department of Dental Material Sciences, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands
| | - Marilia Pivetta Rippe
- Graduate Program in Oral Science, Prosthodontics Units, UFSM - Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Gabriel Kalil Rocha Pereira
- Graduate Program in Oral Science, Prosthodontics Units, UFSM - Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.,Graduate Program in Dentistry, School of Dentistry, IMED - Faculdade Meridional, Passo Fundo, RS, Brazil
| | - Luiz Felipe Valandro
- Graduate Program in Oral Science, Prosthodontics Units, UFSM - Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
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Madruga CFL, Bueno MG, Dal Piva AMDO, Prochnow C, Pereira GKR, Bottino MA, Valandro LF, de Melo RM. Sequential usage of diamond bur for CAD/CAM milling: Effect on the roughness, topography and fatigue strength of lithium disilicate glass ceramic. J Mech Behav Biomed Mater 2019; 91:326-334. [DOI: 10.1016/j.jmbbm.2018.12.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/24/2018] [Accepted: 12/27/2018] [Indexed: 11/15/2022]
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Mechanical performance of Y-TZP monolithic ceramic after grinding and aging: Survival estimates and fatigue strength. J Mech Behav Biomed Mater 2018; 87:288-295. [DOI: 10.1016/j.jmbbm.2018.07.041] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 07/25/2018] [Accepted: 07/29/2018] [Indexed: 12/21/2022]
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26
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Prochnow C, Pereira GKR, Venturini AB, Scherer MM, Rippe MP, Bottino MC, Kleverlaan CJ, Valandro LF. How does hydrofluoric acid etching affect the cyclic load-to-failure of lithium disilicate restorations? J Mech Behav Biomed Mater 2018; 87:306-311. [DOI: 10.1016/j.jmbbm.2018.07.040] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 07/25/2018] [Accepted: 07/29/2018] [Indexed: 12/21/2022]
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Fatigue behavior and surface characterization of a Y-TZP after laboratory grinding and regeneration firing. J Mech Behav Biomed Mater 2018; 88:305-312. [PMID: 30196186 DOI: 10.1016/j.jmbbm.2018.08.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/07/2018] [Accepted: 08/19/2018] [Indexed: 11/20/2022]
Abstract
This study evaluated the effect of grinding and regeneration firing on the flexural fatigue limit and surface characterization of Lava™ Y-TZP ceramic. Forty bar-shaped specimens with 20 × 4.0 × 1.2 mm constituted the as-sintered group (AS = control group), and 80 specimens with 20 × 4.0 × 1.5 mm were ground with cylindrical laboratory stone under water-cooling (WG) or in a dry condition (G) to reach 1.2 mm in thickness. Half of specimens were submitted to regeneration firing (1000 °C, 30 min), forming the groups AS/R, WG/R and G/R. Fatigue limit (500,000 cycles, 10 Hz) was determined by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey HSD tests (α = 0.05). The surface topography (n = 3) and fracture area (n = 3) were evaluated by SEM. Samples were also analyzed by Rietveld refinement from X-ray diffraction data. ANOVA revealed significant differences (P < .001) for grinding protocol, regeneration firing and their interaction. In the groups not submitted to regeneration firing, the mean flexural fatigue limit of WG was higher (P < .05) than that of G and AS, with no statistical difference between each other (P > .05). After regeneration firing the inequality WG>AS>G (P < .05) was observed. The regeneration firing increased the fatigue limit of AS group and decreased those of G and WG groups (P < .05). Grinding protocols created evident grooves on zirconia surface. Failures initiated on tensile side of all specimens. The percentages (wt%) of monoclinic phase before cyclic loading were: AS (7.4), AS/R (6.5), G (2.8), G/R (0.0), WG (4.4), WG/R (0.0); and after cyclic loading: AS (8.6), AS/R (1.2), G (2.4), G/R (5.7), WG (6.3), WG/R (0.0). Wet grinding did not compromise the fatigue limit of zirconia, increasing its mechanical strength. Regeneration firing reduced the fatigue limit of ground samples, despite reducing the amount of monoclinic phase in all experimental conditions.
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Aurélio IL, Prochnow C, Guilardi LF, Ramos GF, Bottino MA, May LG. The effect of extended glaze firing on the flexural fatigue strength of hard-machined ceramics. J Prosthet Dent 2018; 120:755-761. [PMID: 29961617 DOI: 10.1016/j.prosdent.2018.01.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 01/03/2018] [Accepted: 01/03/2018] [Indexed: 11/17/2022]
Abstract
STATEMENT OF PROBLEM It is unclear whether an extended glaze firing could improve the long-term mechanical performance of densely sintered CAD-CAM ceramics. PURPOSE The purpose of this in vitro study was to analyze the effect of an extended glaze firing on the flexural fatigue strength (FFS) of densely sintered milled (hard-machined) leucite-based (LEU) and lithium disilicate-based (DIS) ceramics. MATERIAL AND METHODS Disks were machined from ceramic blocks and divided into 6 groups (n=20) according to the material, LEU or DIS, and to the applied glaze firing: manufacturer-recommended glaze (G group), extended glaze (EG group), and control/no firing (C group). The surface roughness of the disks was measured before and after firing by using a contact profilometer, and data were compared by paired sample tests. Specimens were submitted to fatigue by using the staircase test design in water (piston-on-3 balls; 500 000 cycles, 20 Hz, and sinusoidal loading). Mean (±SD) FFS values were then calculated and analyzed by using 1-way analysis of variance and post hoc Tukey test (α=.05). RESULTS Surface roughness did not change after the firing (P>.05). The highest FFS value in both ceramics was obtained after EG firing (LEU-EG=80.52 ±6.3 MPa; DIS-EG=147.25 ±10.5 MPa), which was statistically superior to G firing (LEU-G=73 ±6.8 MPa, P=.003; DIS-G=134.34 ±15.6 MPa; P=.023) and C group (LEU-C=61.94 ±6.3 MPa; P<.001; DIS-C=134.13 ±17.3 MPa; P=.023). CONCLUSIONS EG firing optimized the biaxial flexural fatigue strength of hard-machined leucite and lithium disilicate ceramics compared with conventional glaze firing.
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Affiliation(s)
- Iana Lamadrid Aurélio
- Professor, Faculty of Dentistry, University Center of Serra Gaúcha FSG, Rio Grande do Sul, Brazil.
| | - Catina Prochnow
- Doctoral student, Department of Restorative Dentistry, Faculty of Dentistry, Federal University of Santa Maria, Rio Grande do Sul, Brazil
| | - Luís Felipe Guilardi
- Doctoral student, Department of Restorative Dentistry, Faculty of Dentistry, Federal University of Santa Maria, Rio Grande do Sul, Brazil
| | - Gabriela Freitas Ramos
- Doctoral student, Department of Restorative Dentistry, São José dos Campos Dental School, São Paulo State University, São Paulo, Brazil
| | - Marco Antonio Bottino
- Titular Professor, Department of Restorative Dentistry, São José dos Campos Dental School, São Paulo State University, São Paulo, Brazil
| | - Liliana Gressler May
- Adjunct Professor, Department of Restorative Dentistry, Faculty of Dentistry, Federal University of Santa Maria, Rio Grande do Sul, Brazil
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Monteiro JB, Riquieri H, Prochnow C, Guilardi LF, Pereira GKR, Borges ALS, de Melo RM, Valandro LF. Fatigue failure load of two resin-bonded zirconia-reinforced lithium silicate glass-ceramics: Effect of ceramic thickness. Dent Mater 2018; 34:891-900. [DOI: 10.1016/j.dental.2018.03.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 03/08/2018] [Accepted: 03/12/2018] [Indexed: 11/16/2022]
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Amaral M, Weitzel ISSL, Silvestri T, Guilardi LF, Pereira GKR, Valandro LF. Effect of grinding and aging on subcritical crack growth of a Y-TZP ceramic. Braz Oral Res 2018; 32:e32. [PMID: 29723335 DOI: 10.1590/1807-3107bor-2018.vol32.0032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 03/09/2018] [Indexed: 11/22/2022] Open
Abstract
This study aimed to investigate slow crack growth (SCG) behavior of a zirconia ceramic after grinding and simulated aging with low-temperature degradation (LTD). Complementary analysis of hardness, surface topography, crystalline phase transformation, and roughness were also measured. Disc-shaped specimens (15 mm Ø × 1.2 mm thick, n = 42) of a full-contour Y-TZP ceramic (Zirlux FC, Amherst) were manufactured according to ISO:6872-2008, and then divided into: Ctrl - as-sintered condition; Ctrl LTD - as-sintered after aging in autoclave (134°C, 2 bar, 20 h); G - ground with coarse diamond bur (grit size 181 μm); G LTD - ground and aged. The SCG parameters were measured by a dynamic biaxial flexural test, which determines the tensile stress versus stress rate under four different rates: 100, 10, 1 and 0.1 MPa/s. LTD led to m-phase content increase, as well as grinding (m-phase content: Ctrl - 0%; G - 12.3%; G LTD - 59.9%; Ctrl LTD - 81%). Surface topography and roughness analyses showed that grinding created an irregular surface (increased roughness) and aging did not promote any relevant surface change. There was no statistical difference on surface hardness among different conditions. The control group presented the lowest strength values in all tested rates. Regarding SCG, ground conditions were less susceptible to SCG, delaying its occurrence. Aging (LTD) caused an increase in SCG susceptibility for the as-sintered condition (i.e. G < G LTD < Ctrl < Ctrl LTD).
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Affiliation(s)
- Marina Amaral
- Department of Dentistry, Universidade de Taubaté - Unitau, Taubaté, SP, Brazil
| | | | - Tais Silvestri
- Post Graduation Program in Dental Science, Prosthetic Dentistry Unit, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS, Brazil
| | - Luis Felipe Guilardi
- Post Graduation Program in Dental Science, Prosthetic Dentistry Unit, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS, Brazil
| | | | - Luiz Felipe Valandro
- Post Graduation Program in Dental Science, Prosthetic Dentistry Unit, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS, Brazil
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Heintze SD, Monreal D, Reinhardt M, Eser A, Peschke A, Reinshagen J, Rousson V. Fatigue resistance of all-ceramic fixed partial dentures - Fatigue tests and finite element analysis. Dent Mater 2018; 34:494-507. [PMID: 29395474 DOI: 10.1016/j.dental.2017.12.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 12/11/2017] [Accepted: 12/16/2017] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To estimate the fatigue resistance of a new translucent zirconia material in comparison to lithium disilicate for 3-unit fixed partial dentures (FPDs). METHODS Eighteen 3-unit FPDs (replacement of first upper molar) with a connector size of 4mm×4mm were dry milled with a five-axis milling machine (Zenotec Select, Wieland, Germany) using discs made of a new translucent zirconia material (IPS e.max ZirCAD MT, Ivoclar Vivadent). Another 9 FPDs with a reduced connector size (3mm×4mm) were milled. The zirconia FPDs were sintered at 1500°C. For a comparison, 9 FPDs were made of IPS e.max Press, using the same dimensions. These IPS e.max Press FPDs were ground from a wax disc (Wieland), invested and pressed at 920°C. All FPDs were glazed twice. The FPDs were adhesively luted to PMMA dies with Multilink Automix. Dynamic cyclic loading was carried out on the molar pontic using Dyna-Mess testing machines (Stolberg, Germany) with 2×106 cycles at 2Hz in water (37°C). Two specimens per group and load were subjected to decreasing load levels (at least 4) until the two specimens no longer showed any failures. Another third specimen was subjected to this load to confirm the result. All the specimens were evaluated under a stereo microscope (20× magnification). The number of cycles reached before observing a failure, and their dependence on the load and on the material, were modeled, using a Weibull model. This made it possible to estimate the fatigue resistance as the maximum load for which one would observe less than 1% failure after 2×106 cycles. In addition to the experimental study, Finite Element Modeling (FEM) simulations were conducted to predict the force to failure for IPS e.max ZirCAD MT and IPS e.max Press with a reduced cross-section of the connectors. RESULTS The failure mode of the zirconia FPDs was mostly the fracture of the distal connector, whereas the failure mode of the lithium disilicate FPDs observed to be the fracture of the connectors or multiple cracks of the pontic. The fatigue resistance with 1% fracture probability was estimated to be 488N for the IPS e.max ZirCAD MT FPDs (453N for repeated test), 365N for IPS e.max ZirCAD MT FPDs with reduced connector size and 286N for the e.max Press FPDs. All three IPS e.max ZirCAD groups statistically performed significantly better than IPS e.max Press (p<0.001). On the other hand, no significant difference could be established between the two IPS e.max ZirCAD MT3 groups with a 4mm×4mm connector size (p>0.05). The allowable maximum principal stress (σmax) which did not lead to failure during fatigue testing for IPS e.max ZirCAD MT3 was calculated between 208MPa and 223MPa for FPDs with 4mm×4mm connectors for 2×106 cycles. This value could also be verified for the FPDs of the same material with 3mm×4mm connectors. On the other hand fatigue strength in terms of σmax at 2×106 cycles of IPS e.max Press was calculated to be between 78 and 90MPa. SIGNIFICANCE The fatigue resistance of the translucent zirconia 3-unit FPDs was about 60-70% higher than that of the lithium disilicate 3-unit FPDs, which may justify their use for molar replacements, provided that a minimal connector size of 4mm×4mm is observed. Even with a limited number of specimens (n=9) per group it was possible to statistically differentiate between the tested groups.
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Affiliation(s)
- S D Heintze
- R&D, Ivoclar Vivadent AG, Bendererstrasse 2, FL-9494 Schaan, Liechtenstein.
| | - D Monreal
- R&D, Ivoclar Vivadent AG, Bendererstrasse 2, FL-9494 Schaan, Liechtenstein
| | - M Reinhardt
- R&D, Ivoclar Vivadent AG, Bendererstrasse 2, FL-9494 Schaan, Liechtenstein
| | - A Eser
- R&D, Ivoclar Vivadent AG, Bendererstrasse 2, FL-9494 Schaan, Liechtenstein
| | - A Peschke
- R&D, Ivoclar Vivadent AG, Bendererstrasse 2, FL-9494 Schaan, Liechtenstein
| | | | - V Rousson
- University Hospital Lausanne, Biostatistical Division, Institute for Social and Preventive Medicine, Switzerland
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Silvestri T, Pereira GKR, Guilardi LF, Rippe MP, Valandro LF. Effect of Grinding and Multi-Stimuli Aging on the Fatigue Strength of a Y-TZP Ceramic. Braz Dent J 2018; 29:60-67. [DOI: 10.1590/0103-6440201801735] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 10/16/2017] [Indexed: 01/07/2023] Open
Abstract
Abstract This study aimed to investigate the effect of grinding and multi-stimuli aging on the fatigue strength, surface topography and the phase transformation of Y-TZP ceramic. Discs were manufactured according to ISO-6872:2008 for biaxial flexure testing (diameter: 15 mm; thickness: 1.2 mm) and randomly assigned considering two factors “grinding” and “aging”: C- control (as-sintered); CA- control + aging; G- ground; GA- ground + aging. Grinding was carried out with coarse diamond burs under water-cooling. Aging protocols consisted of: autoclave (134°C, 2 bars pressure, 20 hours), followed by storage for 365 days (samples were kept untouched at room temperature), and by mechanical cycling (106 cycles by 20 Hz under a load of 50% from the biaxial flexure monotonic tests). Flexural fatigue strengths (20,000 cycles; 6 Hz) were determined under sinusoidal cyclic loading using staircase approach. Additionally, surface topography analysis by FE-SEM and phase transformation analysis by X-ray Diffractometry were performed. Dixon and Mood methodology was used to analyze the fatigue strength data. Grinding promotes alterations of topographical pattern, while aging apparently did not alter it. Grinding triggered t-m phase transformation without impacting the fatigue strength of the Y-TZP ceramic; and aging promoted an intense t-m transformation that resulted in a toughening mechanism leading to higher fatigue strength for as-sintered condition, and a tendency of increase for ground condition (C < CA; G = GA). It concludes that grinding and aging procedures did not affect deleteriously the fatigue strength of the evaluated Y-TZP ceramic, although, it promotes surface topography alterations, except to aging, and t-m phase transformation.
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PRADO RD, PEREIRA GKR, BOTTINO MA, MELO RMD, VALANDRO LF. Effect of ceramic thickness, grinding, and aging on the mechanical behavior of a polycrystalline zirconia. Braz Oral Res 2017; 31:e82. [DOI: 10.1590/1807-3107bor-2017.vol31.0082] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 08/14/2017] [Indexed: 11/22/2022] Open
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Zucuni CP, Guilardi L, Rippe M, Pereira GK, Valandro L. Fatigue strength of yttria-stabilized zirconia polycrystals: Effects of grinding, polishing, glazing, and heat treatment. J Mech Behav Biomed Mater 2017; 75:512-520. [DOI: 10.1016/j.jmbbm.2017.06.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/09/2017] [Accepted: 06/12/2017] [Indexed: 02/04/2023]
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Monteiro JB, Oliani MG, Guilardi LF, Prochnow C, Rocha Pereira GK, Bottino MA, de Melo RM, Valandro LF. Fatigue failure load of zirconia-reinforced lithium silicate glass ceramic cemented to a dentin analogue: Effect of etching time and hydrofluoric acid concentration. J Mech Behav Biomed Mater 2017; 77:375-382. [PMID: 28988143 DOI: 10.1016/j.jmbbm.2017.09.028] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 09/15/2017] [Accepted: 09/18/2017] [Indexed: 10/18/2022]
Abstract
This study aimed to evaluate the effect of etching time and hydrofluoric acid (HF) concentration on the fatigue failure load and surface characteristics of zirconia-reinforced lithium silicate glass (ZLS) ceramic cemented to a dentin-like, fiber reinforced epoxy resin. Ceramic (Suprinity, VITA) (1.0mm thick) and epoxy resin (2.5mm thick) discs (10mm diameter) were produced. The bonding surface of the ceramic samples was nonetched (control group), or etched for 30, 60 or 90s by 5% or 10% HF. The epoxy resin discs were etched by 10% HF for 30s followed by the application of an adhesive material (Single Bond Universal, 3M ESPE). Pairs of ceramic/epoxy resin discs were cemented with a dual cure resin cement. The fatigue failure load was determined by the staircase method (500,000 cycles at 20Hz; initial load = 925N; step size = 45N). In 10% HF the etching time was shown to influence the fatigue failure load, which increased as the etching time increased (30s < 60s < 90s), and in 5% HF the fatigue failure load was not shown to be affected by the etching time; the lowest fatigue failure loads were produced in the control group without ceramic etching followed by 10% HF acid etching for 30s. Topography analysis showed variations based on the etching protocols. All fractures (radial cracks) were shown to originate from defects at the ceramic surface on the cementing interface. For fatigue loading improvements of ZLS ceramic, 10% HF acid etching for 90s and silanization of the ceramic surface is recommended.
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Affiliation(s)
- Jaiane Bandoli Monteiro
- PhD Post-Graduate Program in Restorative Dentistry (Prosthodontics Units), Univ. Estadual Paulista (UNESP), Institute of Science and Technology at Sao Jose dos Campos, Sao Jose dos Campos, Sao Paulo State, Brazil.
| | - Marcelo Gallo Oliani
- PhD Post-Graduate Program in Restorative Dentistry (Prosthodontics Units), Univ. Estadual Paulista (UNESP), Institute of Science and Technology at Sao Jose dos Campos, Sao Jose dos Campos, Sao Paulo State, Brazil.
| | - Luis Felipe Guilardi
- PhD Post-Graduate Program in Oral Science (Prosthodontic Units), Faculty of Odontology, Federal University of Santa Maria, R. Floriano Peixoto, 1184, 97015-372 Santa Maria, Rio Grande do Sul, Brazil.
| | - Catina Prochnow
- PhD Post-Graduate Program in Oral Science (Prosthodontic Units), Faculty of Odontology, Federal University of Santa Maria, R. Floriano Peixoto, 1184, 97015-372 Santa Maria, Rio Grande do Sul, Brazil.
| | - Gabriel Kalil Rocha Pereira
- PhD Post-Graduate Program in Oral Science (Prosthodontic Units), Faculty of Odontology, Federal University of Santa Maria, R. Floriano Peixoto, 1184, 97015-372 Santa Maria, Rio Grande do Sul, Brazil; MSciD Graduate Program, School of Dentistry, Meridional Faculty - IMED, Passo Fundo, Rio Grande do Sul, Brazil.
| | - Marco Antonio Bottino
- PhD Post-Graduate Program in Restorative Dentistry (Prosthodontics Units), Univ. Estadual Paulista (UNESP), Institute of Science and Technology at Sao Jose dos Campos, Sao Jose dos Campos, Sao Paulo State, Brazil.
| | - Renata Marques de Melo
- PhD Post-Graduate Program in Restorative Dentistry (Prosthodontics Units), Univ. Estadual Paulista (UNESP), Institute of Science and Technology at Sao Jose dos Campos, Sao Jose dos Campos, Sao Paulo State, Brazil.
| | - Luiz Felipe Valandro
- PhD Post-Graduate Program in Oral Science (Prosthodontic Units), Faculty of Odontology, Federal University of Santa Maria, R. Floriano Peixoto, 1184, 97015-372 Santa Maria, Rio Grande do Sul, Brazil.
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Lai X, Si W, Jiang D, Sun T, Shao L, Deng B. Effects of small-grit grinding and glazing on mechanical behaviors and ageing resistance of a super-translucent dental zirconia. J Dent 2017; 66:23-31. [PMID: 28916163 DOI: 10.1016/j.jdent.2017.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/31/2017] [Accepted: 09/11/2017] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES The purpose of this study is to elucidate the effects of small-grit grinding on the mechanical behaviors and ageing resistance of a super-translucent dental zirconia and to investigate the necessity of glazing for the small-grit ground zirconia. METHODS Small-grit grinding was performed using two kinds of silicon carbide abrasive papers. The control group received no grinding. The unground surfaces and the ground surfaces were glazed by an experienced dental technician. Finally, the zirconia materials were thermally aged in water at 134°C for 5h. After aforementioned treatments, we observed the surface topography and the microstructures, and measured the extent of monoclinic phase, the nano-hardness and nano-modulus of the possible transformed zone and the flexural strength. RESULTS Small-grit grinding changed the surface topography. The zirconia microstructure did not change obviously after surface treatments and thermal ageing; however, the glaze in contact with zirconia showed cracks after thermal ageing. Small-grit grinding did not induce a phase transformation but improved the flexural strength and ageing resistance. Glazing prevented zirconia from thermal ageing but severely diminished the flexural strength. The nano-hardness and nano-modulus of the surface layer were increased by ultrafine grinding. CONCLUSIONS The results suggest that small-grit grinding is beneficial to the strength and ageing resistance of the super-translucent dental zirconia; however, glazing is not necessary and even impairs the strength for the super-translucent dental zirconia. CLINICAL SIGNIFICANCE This study is helpful to the researches about dental grinding tools and maybe useful for dentists to choose reasonable zirconia surface treatments.
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Affiliation(s)
- Xuan Lai
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Wenjie Si
- School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Danyu Jiang
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Shanghai, 200050, China
| | - Ting Sun
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Longquan Shao
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
| | - Bin Deng
- Department of the Prosthodontics, The General Hospital of Chinese PLA, Beijing, 100853, China.
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Wandscher VF, Prochnow C, Rippe MP, Dorneles LS, Callegari GL, Baldissara P, Scotti R, Valandro LF. Retentive Strength of Y-TZP Crowns: Comparison of Different Silica Coating Methods on the Intaglio Surfaces. Oper Dent 2017; 42:E121-E133. [DOI: 10.2341/16-090-l] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
SUMMARY
Objective:
To evaluate the effect of different methods of silica deposition on the intaglio surface of yttrium oxide stabilized zirconia polycrystal (Y-TZP) crowns on the retentive strength of the crowns.
Methods:
One hundred simplified full-crown preparations produced from fiber-reinforced polymer material were scanned, and 100 Y-TZP crowns with occlusal retentions were milled. Crown/preparation assemblies were randomly allocated into five groups (n=20) according to the treatment of the intaglio surfaces: TBS = tribochemical silica coating via air-abrasion with 30-μm silica-coated alumina particles; GHF1 = application of thin glaze layer + hydrofluoric acid (HF) etching for 1 minute; GHF5 = glaze application + HF for 5 minutes; GHF15 = glaze application + HF for 15 minutes; NANO = silica nanofilm deposition (5 nm) via magnetron sputtering. All groups received a silane application. The surfaces of the preparations (polymer) were conditioned with 10% HF for 30 seconds and silanized. The crowns were cemented with resin cement, thermocycled (12,000 cycles; 5°C/55°C), stored for 60 days, and subjected to a retentive strength test (0.5 mm/min until failure). The retention data (MPa) were analyzed using one-way analysis of variance, Tukey tests, and Weibull analysis. Failures were classified as 50C (above 50% of cement in the crown) and 50S (above 50% of cement on the substrate).
Results:
The TBS (5.6±1.7 MPa) and NANO groups (5.5±1 MPa) had higher retentive strength than the other groups (p<0.0001) and had the highest values of characteristic strength. There was no difference in Weibull modulus, except for the GHF1 group (lower values). The TBS and GHF15 groups, respectively, had 60% and 70% of their failures classified as 50C, while most of the other groups had 50S failures.
Conclusion:
Tribochemical silica coating and silica nanofilm deposition on the inner surface of zirconia crowns promoted a higher retentive strength.
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Affiliation(s)
- VF Wandscher
- Vinicius F. Wandscher, DDS, MSD, PhD, adjucnt professor, Faculty of Odontology (Prosthetic Dentistry Unit), Franciscan University Center, Santa Maria, Rio Grande do Sul State, Brazil
| | - C Prochnow
- Catina Prochnow, DDS, MSD, PhD student, Post-graduate Program in Oral Science (Prosthetic Dentistry Unit), Federal University of Santa Maria, Santa Maria, Brazil
| | - MP Rippe
- Marilia Pivetta Rippe, DDS, MSD, PhD, adjunct professor, Restorative Dentistry (Prosthetic Dentistry Unit), Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil
| | - LS Dorneles
- Lucio S. Dorneles, PhD, associate professor, Physics Department, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil
| | - GL Callegari
- Gustavo L. Callegari, PhD, Physics Department, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil
| | - P Baldissara
- Paolo Baldissara, DDS, assistant professor and researcher, Biomedical Sciences and Neuromotor (Prosthetic Dentistry Unit), Alma Mater Studiorum University of Bologna, Bologna, Italy
| | - R Scotti
- Roberto Scotti, professor, Biomedical Sciences and Neuromotor (Prosthodontics), Alma Mater Studiorum University of Bologna, Bologna, Italy
| | - LF Valandro
- Luiz Felipe Valandro, DDS, MSD, PhD, associate professor, Restorative Dentistry (Prosthetic Dentistry Unit), Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil
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Chen C, Chen Y, Lu Z, Qian M, Xie H, Tay FR. The effects of water on degradation of the zirconia-resin bond. J Dent 2017; 64:23-29. [PMID: 28414171 DOI: 10.1016/j.jdent.2017.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 04/07/2017] [Accepted: 04/09/2017] [Indexed: 10/19/2022] Open
Abstract
OBJECTIVES 10-methacryloyloxydecyldihydrogenphosphate (MDP) containing primers improve bonding of yttria-stabilised tetragonal zirconia (Y-TZP) to methacrylate resins. The present study investigated the role played by water in the deterioration of MDP-mediated zirconia-resin bonds. METHODS Grit-blasted Y-TZP plates were conditioned with two MDP primers and bonded with resin for shear bond strength (SBS) testing. Additional bonded plates were aged hydrothermally and compared with unaged Y-TZP after 24h of water-storage or 6 months of water/acid/alkali-storage. The monoclinic phase (m-ZrO2) in different groups was determined by X-ray diffraction. Hydrolytic stability of the coordinate bond between MDP and zirconia in neutral/acid/alkaline environment was analysed using thermodynamic calculations. Microleakage and release of the element phosphorus from MDP-mediated Y-TZP/resin-bonded interfaces were evaluated via methylene blue dye infiltration and inductively coupled plasma-mass spectrometry (ICP-MS). RESULTS Hydrothermal ageing did not significantly alter SBS. Ageing in acidic or neutral medium led to significant decline in SBS. The m-ZrO2 phase increased after hydrothermal ageing but no m-ZrO2 was detected in the water/acid/alkali-aged specimens. A higher equilibrium constant was identified in the MDP-t-ZrO2 complex when compared with the MDP-m-ZrO2 complex. MDP-conditioning failed to prevent infiltration of the methylene blue dye. Phosphorus was detected by ICP-MS from the solutions used for soaking the resin-bonded specimens. CONCLUSIONS Hydrolysis of the coordinate bond between MDP and ZrO2, rather than t→m phase transformation, weakens the bond integrity between MDP-conditioned Y-TZP and methacrylate resin. CLINICAL SIGNIFICANCE Hydrolysis of the coordinate bond between MDP and zirconia is responsible for deterioration of the integrity of the bond between MDP-conditioned Y-TZP and methacrylate resin.
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Affiliation(s)
- C Chen
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
| | - Y Chen
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
| | - Z Lu
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
| | - M Qian
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
| | - H Xie
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
| | - F R Tay
- Department of Endodontics, The Dental College of Georgia, Augusta University, Augusta, GA, 30912, USA.
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Zucuni CP, Guilardi LF, Fraga S, May LG, Pereira GKR, Valandro LF. CAD/CAM machining Vs pre-sintering in-lab fabrication techniques of Y-TZP ceramic specimens: Effects on their mechanical fatigue behavior. J Mech Behav Biomed Mater 2017; 71:201-208. [PMID: 28343087 DOI: 10.1016/j.jmbbm.2017.03.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/11/2017] [Accepted: 03/14/2017] [Indexed: 12/22/2022]
Abstract
This study evaluated the effects of different pre-sintering fabrication processing techniques of Y-TZP ceramic (CAD/CAM Vs. in-lab), considering surface characteristics and mechanical performance outcomes. Pre-sintered discs of Y-TZP ceramic (IPS e.max ZirCAD, Ivoclar Vivadent) were produced using different pre-sintering fabrication processing techniques: Machined- milling with a CAD/CAM system; Polished- fabrication using a cutting device followed by polishing (600 and 1200 SiC papers); Xfine- fabrication using a cutting machine followed by grinding with extra-fine diamond bur (grit size 30 μm); Fine- fabrication using a cutting machine followed by grinding with fine diamond bur (grit size 46 μm); SiC- fabrication using a cutting machine followed by grinding with 220 SiC paper. Afterwards, the discs were sintered and submitted to roughness (n=35), surface topography (n=2), phase transformation (n=2), biaxial flexural strength (n=20), and biaxial flexural fatigue strength (fatigue limit) (n=15) analyses. No monoclinic-phase content was observed in all processing techniques. It can be observed that obtaining a surface with similar characteristics to CAD/CAM milling is essential for the observation of similar mechanical performance. On this sense, grinding with fine diamond bur before sintering (Fine group) was the best mimic protocol in comparison to the CAD/CAM milling.
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Affiliation(s)
- C P Zucuni
- MSciD-PhD Graduate Programs in Oral Science, Prosthodontics Units, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
| | - L F Guilardi
- MSciD-PhD Graduate Programs in Oral Science, Prosthodontics Units, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
| | - S Fraga
- MSciD-PhD Graduate Programs in Oral Science, Prosthodontics Units, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
| | - L G May
- MSciD-PhD Graduate Programs in Oral Science, Prosthodontics Units, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
| | - G K R Pereira
- MSciD-PhD Graduate Programs in Oral Science, Prosthodontics Units, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil; MSciD Graduate Program, School of Dentistry, Meridional Faculty - IMED, Passo Fundo, Rio Grande do Sul, Brazil.
| | - L F Valandro
- MSciD-PhD Graduate Programs in Oral Science, Prosthodontics Units, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
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Amaral M, Villefort RF, Melo RM, Pereira GKR, Zhang Y, Valandro LF, Bottino MA. Fatigue limit of monolithic Y-TZP three-unit-fixed dental prostheses: Effect of grinding at the gingival zone of the connector. J Mech Behav Biomed Mater 2017; 72:159-162. [PMID: 28494273 DOI: 10.1016/j.jmbbm.2017.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/03/2017] [Accepted: 03/05/2017] [Indexed: 11/19/2022]
Abstract
OBJECTIVES To determine the fatigue limits of three-unit monolithic zirconia fixed dental prosthesis (FDPs) before and after grinding of the gingival areas of connectors with diamond burs. MATERIAL AND METHODS FDPs were milled from pre-sintered blocks of zirconia simulating the absence of the first mandibular molar. Half of the specimens were subjected to grinding, simulating clinical adjustment, and all of them were subjected to glazing procedure. Additional specimens were manufactured for roughness analysis. FDPs were adhesively cemented onto glass-fiber reinforced epoxy resin abutments. Fatigue limits and standard deviations were obtained using a staircase fatigue method (n=20, 100,000 loading cycles/5Hz). The initial test load was 70% of the mean load-to-fracture (n=3) and load increments were 5% of the initial test load for both the control and ground specimens. Data were compared by Student's T-test (α≤0.05). RESULTS Both the control and ground groups exhibited similar values of load-to-fracture and fatigue limits. Neither the surface treatments nor ageing affected the surface roughness of the specimens. CONCLUSIONS The damage induced by grinding with fine-grit diamond bur in the gingival area of the connectors did not decrease the fatigue limit of the three-unit monolithic zirconia FDP.
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Affiliation(s)
- Marina Amaral
- Department of Dentistry, Dental Prosthesis, University of Taubate, Taubaté, São Paulo State, Brazil
| | - Regina F Villefort
- Post Graduation Program in Restorative Dentistry (Prosthetic Dentistry Unit), School of Dentistry, Sao Paulo State University, São José dos Campos, São Paulo State, Brazil
| | - Renata Marques Melo
- Post Graduation Program in Restorative Dentistry, School of Dentistry, Sao Paulo State University, São José dos Campos, São Paulo State, Brazil
| | - Gabriel K R Pereira
- Post Graduation Program in Dental Sciences, School of Dentistry, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil
| | - Yu Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 First Avenue, New York, NY, USA
| | - Luiz Felipe Valandro
- Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
| | - Marco Antonio Bottino
- Department of Dental Materials and Prosthesis, School of Dentistry, Sao Paulo State University, São José dos Campos, São Paulo State, Brazil
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Guilardi LF, Pereira GKR, Gündel A, Rippe MP, Valandro LF. Surface micro-morphology, phase transformation, and mechanical reliability of ground and aged monolithic zirconia ceramic. J Mech Behav Biomed Mater 2016; 65:849-856. [PMID: 27810731 DOI: 10.1016/j.jmbbm.2016.10.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Revised: 10/14/2016] [Accepted: 10/18/2016] [Indexed: 10/20/2022]
Abstract
This study aimed to determine the effects of grinding and low temperature aging on the biaxial flexural strength, structural reliability (Weibull analysis), surface topography, roughness analysis, and phase transformation (t→m) of an yttrium-stabilized tetragonal zirconia polycrystalline ceramic. Ceramic discs (15.0×1.2±0.2mm, VITA In-Ceram YZ) were prepared and randomly assigned into six groups according to 2 factors (n=30): 'grinding' (Ctrl - without treatment, as-sintered; Xfine - grinding with extra fine diamond bur - 30µm; Coarse - grinding by coarse diamond bur - 151µm), and 'aging' (without or with aging: CtrlLTD; XfineLTD; CoarseLTD). Grinding was performed in an oscillatory motion with a contra-angle handpiece under constant water-cooling. Low temperature degradation (LTD) was simulated in an autoclave at 134°C, under 2bar pressure, for 20h. The roughness (Ra and Rz parameters) significantly increased after grinding in accordance with bur grit-size (Coarse>Xfine>Ctrl), and aging promoted distinct effects (Ctrl=CtrlLTD; Xfine>XfineLTD; Coarse=CoarseLTD). Grinding increased the m-phase, and aging led to an increase in the m-phase in all groups. However, different susceptibilities to LTD were observed. Weibull analysis showed a significant increase in the characteristic strength after grinding (Coarse=Xfine>Ctrl), while aging did not lead to any deleterious impact. Neither grinding nor aging resulted in any deleterious impact on material reliability (no statistical decrease in the Weibull moduli). Thus, neither grinding nor aging led to a deleterious effect on the mechanical properties of the evaluated Y-TZP ceramic although a high m-phase content and roughness were observed.
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Affiliation(s)
- L F Guilardi
- MSc-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
| | - G K R Pereira
- MSc-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
| | - A Gündel
- Physics School, Federal University of Pampa, Bage, Rio Grande do Sul State, Brazil.
| | - M P Rippe
- MSc-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
| | - L F Valandro
- MSc-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul State, Brazil.
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Polli GS, Hatanaka GR, Abi-Rached FDO, Pinelli LAP, Góes MDS, Cesar PF, Reis JMDSN. Effect of Grinding and Resintering on the Fatigue Limit and Surface Characterization of a Y-TZP Ceramic. Braz Dent J 2016; 27:468-75. [PMID: 27652713 DOI: 10.1590/0103-6440201600801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 05/09/2016] [Indexed: 11/21/2022] Open
Abstract
This study evaluated the effect of grinding protocols and resintering on flexural fatigue limit and surface characterization of LavaTM Y-TZP. Bar-shaped specimens (20×4.0×1.2 mm, n=40; 20×4.0×1.5 mm, n=80) were obtained. Half of the thinner specimens (1.2 mm) constituted the as-sintered group (AS), while the thicker ones (1.5 mm) were ground with diamond burs under irrigation (WG) or not (G). The other half of thinner and half of ground specimens were resintered (1000 ºC, 30 min), forming the groups ASR, WGR and GR. Fatigue limit (500,000 cycles, 10 Hz) was evaluated by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey's test (α=0.05). Surface topography (n=3) and fracture area (n=3) were evaluated by SEM. X-ray diffraction data (n=1) was analyzed by Rietveld refinement. ANOVA revealed significant differences (p<0.001) for the grinding protocol, resintering and their interaction. Grinding increased the fatigue limit of non-resintered groups. There was no significant difference among the resintered groups. Resintering significantly increased the fatigue limit of the AS group only. Both protocols created evident grooves on zirconia surface. The failures initiated at the tensile side of all specimens. The percentages (wt%) of monoclinic phase were AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) before, and AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) after cyclic loading. Grinding increased the fatigue limit of non-resintered Y-TZP and formed evident grooves on its surface. Resintering provided significant increase in the fatigue limit of as-sintered specimens. In general, grinding and resintering decreased or zeroed the monoclinic phase.
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Affiliation(s)
- Gabriela Scatimburgo Polli
- Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil
| | - Gabriel Rodrigues Hatanaka
- Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil
| | - Filipe de Oliveira Abi-Rached
- Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil
| | - Lígia Antunes Pereira Pinelli
- Department of Dental Materials and Prosthodontics, Araraquara Dental School, UNESP - Univ Estadual Paulista, Araraquara, SP, Brazil
| | - Márcio de Sousa Góes
- UNILA - Universidade Federal da Integração Latino-Americana, Foz do Iguaçu, PR, Brazil
| | - Paulo Francisco Cesar
- Department of Biomaterials and Oral Biology, Dental School, USP - Universidade de São Paulo, São Paulo, SP, Brazil
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Pereira GKR, Muller C, Wandscher VF, Rippe MP, Kleverlaan CJ, Valandro LF. Comparison of different low-temperature aging protocols: its effects on the mechanical behavior of Y-TZP ceramics. J Mech Behav Biomed Mater 2016; 60:324-330. [PMID: 26921592 DOI: 10.1016/j.jmbbm.2016.02.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/09/2016] [Accepted: 02/10/2016] [Indexed: 10/22/2022]
Abstract
This study evaluated the effect of different protocols of low-temperature degradation simulation on the mechanical behavior (structural reliability and flexural strength), the surface topography (roughness), and phase transformation of a Y-TZP ceramic. Disc-shaped specimens (1.2mm×12mm, Lava Frame, 3M ESPE, Seefeld, Germany) were manufactured according to ISO:6872-2008 and divided (n=30) according to the aging protocol executed: "Ctrl" - as-sintered - without any treatment; "Dist Water" - stored at distilled water at 37°C for 365 days; "MC" mechanical cycling into two steps: First - 200N, 2.2Hz for 2.000.000 cycles, Second - 450N, 10Hz for 1.000.000 cycles; "Aut" - steam autoclave at 134°C, 2bar (200kPa) for 20h; "Aut+MC"- Aut and MC methods. Roughness analysis (μm) showed, for Ra parameter, higher statistically significant values for Ctrl 0.68 (0.27), while for Rz parameter, the highest values were observed for Ctrl 4.43(1.53) and Aut 2.24 (0.62). Surface topography analysis showed that none aging method promoted surface alterations when compared to control group. Phase transformation analysis showed that all aging methods promoted an increase in m-phase content (Ctrl: 0.94%, Dist Water: 20.73%, MC: 9.47%, Aut: 53.33% and Aut+MC: 61.91%). Weibull Analysis showed higher statistical characteristic strength values for Aut (1033.36MPa) and Dist Water (1053.76MPa). No aging method promoted deleterious impact either on the biaxial flexural strengths or on the structural reliabilities (Weibull moduli). Also, none of the aging methods promoted reduction of Y-TZP mechanical properties; thus the development of new methodologies and the association between mechanical stimuli and hydrothermal degradation should be considered to better understand the mechanism of low-temperature degradation.
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Affiliation(s)
- G K R Pereira
- MDS-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
| | - C Muller
- MDS-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
| | - V F Wandscher
- MDS-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
| | - M P Rippe
- Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
| | - C J Kleverlaan
- Department of Dental Material Sciences, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands.
| | - L F Valandro
- Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
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