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Ozdogan A, Tosun B. Effects of repetitive firings on mechanical, optical, and phase formation changes of ceramic materials. J Prosthet Dent 2024; 132:230-240. [PMID: 36889999 DOI: 10.1016/j.prosdent.2023.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 02/02/2023] [Accepted: 02/02/2023] [Indexed: 03/09/2023]
Abstract
STATEMENT OF PROBLEM Studies are sparse on how rapid heating and cooling negatively affect optical properties, including color and transparency, and mechanical properties, including hardness and durability, that affect esthetics and shorten the clinical usage period of the ceramics. PURPOSE The purpose of this in vitro study was to determine the effects of repeated firing on the color difference, mechanical properties, and phase formation of different ceramic materials. MATERIAL AND METHODS A total of 160 disks (12×1.35 mm) were produced from 4 different ceramic materials: lithium disilicate glass-ceramic, zirconia-reinforced lithium silicate ceramic, zirconia core, and monolithic zirconia. Specimens from all groups were divided into 4 groups (n=10) with a different number of veneer porcelain firings (1 to 4) by simple randomization. After the firings, color measurement, X-ray diffraction analysis, environmental scanning electron micrograph analysis, surface roughness evaluation, Vickers hardness evaluation, and biaxial flexural strength tests were performed. Data were analyzed with analysis of variance (2-way ANOVA) (α=.05). RESULTS Repeated firing did not affect the flexural strength of the specimens in any of the groups (P>.05), while the color, surface roughness, and surface hardness were significantly affected (P<.05). The specimens fired 4 times showed the highest mean Vickers hardness and ΔE00 values but the lowest mean surface roughness values. Zirconia core specimens showed the highest mean ΔE00 and flexural strength values, and lithium disilicate glass-ceramic specimens had the highest mean Vickers hardness values. CONCLUSIONS The increase in the number of firings affected the color, mechanical properties, and phase formation of the specimens; this change differed according to the ceramic tested.
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Affiliation(s)
- Alper Ozdogan
- Associate Professor, Department of Prosthodontics, Faculty of Dentistry, Atatürk University, Erzurum, Turkey.
| | - Büsra Tosun
- Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Bolu Abant İzzet Baysal University, Bolu, Turkey
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Al-Johani H, Haider J, Silikas N, Satterthwaite J. Effect of repeated firing on the topographical, optical, and mechanical properties of fully crystallized lithium silicate-based ceramics. J Prosthet Dent 2024; 131:741.e1-741.e11. [PMID: 38242762 DOI: 10.1016/j.prosdent.2024.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 01/02/2024] [Accepted: 01/05/2024] [Indexed: 01/21/2024]
Abstract
STATEMENT OF PROBLEM The influence of different firing protocols on the topographical, optical, and mechanical properties of fully crystallized computer-aided design and computer-aided manufacturing (CAD-CAM) lithium silicate-based glass-ceramics (LSCs) for dental restorations remains unclear. PURPOSE The purpose of this in vitro study was to investigate the effect of different firing regimens on the surface roughness, gloss, Martens hardness, indentation modulus, biaxial flexural strength, and crystalline structure of fully crystallized CAD-CAM LSCs and the effect of their interposition on the irradiance of a light-polymerization unit. MATERIAL AND METHODS Three fully crystallized CAD-CAM LSC blocks were evaluated (N=150): lithium disilicate (Initial LiSi Blocks; LS), zirconia-reinforced silicate (Celtra Duo; CD), and lithium aluminum disilicate (CEREC Tessera; CT). Specimens were allocated to 5 subgroups according to their firing protocol. LSC roughness (Sa) was measured with an optical profilometer, and gloss (GU) was detected with a gloss meter. Martens hardness (HM) and indentation modulus (EIT) data were obtained from a hardness testing machine. The irradiance of a light-polymerization unit and transmittance of LSCs were measured with an instrument (Managing Accurate Resin Curing-Light Collector; BlueLight analytics, Inc) subsequent to ceramic interposition. Crystalline phases were analyzed by X-ray diffraction, and biaxial flexural strength (σ) was determined by the ball-on-3-ball method in a universal testing machine followed by Weibull analysis to calculate characteristic strength (σ0) and Weibull modulus (m). Two-way ANOVA and Tukey HSD post hoc tests (α=.05) were used to analyze the data. RESULTS Statistically significant differences were found among different treatment groups based on Sa, GU, HM, and EIT values (P<.001). Delivered irradiance was significantly reduced following CT (P<.01) and glazed LSC (P<.005) interposition. CD displayed highest biaxial flexural strength and reliability after 1 firing cycle (σ=568.2 MPa, m=16.8) CONCLUSIONS: The type of material and firing regimens had a significant effect on the topographical, optical, and mechanical properties of fully crystallized CAD-CAM LSCs. Glazing significantly reduced delivered irradiance, Martens hardness, and biaxial flexural strength.
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Affiliation(s)
- Hanan Al-Johani
- PhD student, Division of Dentistry, School of Medical Sciences, University of Manchester, Manchester, England, UK
| | - Julfikar Haider
- Associate Professor, Department of Engineering, Manchester Metropolitan University, Manchester, England, UK
| | - Nick Silikas
- Full Professor, Division of Dentistry, School of Medical Sciences, University of Manchester, Manchester, England, UK.
| | - Julian Satterthwaite
- Full Professor, Division of Dentistry, School of Medical Sciences, University of Manchester, Manchester, England, UK
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Lu Y, Dal Piva AMO, Nedeljkovic I, Tribst JPM, Feilzer AJ, Kleverlaan CJ. Effect of glazing technique and firing on surface roughness and flexural strength of an advanced lithium disilicate. Clin Oral Investig 2023:10.1007/s00784-023-05014-1. [PMID: 37178172 DOI: 10.1007/s00784-023-05014-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 03/29/2023] [Indexed: 05/15/2023]
Abstract
OBJECTIVE The objective of this study was to investigate the effects of glazing technique and firing on the surface roughness and flexural strength of an advanced lithium disilicate (ALD) and lithium disilicate (LD). METHODS Eight groups of bar-shaped specimens (1 mm × 1 mm × 12 mm, N=160, 20/group) were manufactured from ALD (CEREC Tessera, Dentsply Sirona) and LD (IPS e.max CAD, Ivoclar). The specimens were then submitted to various posttreatments: crystallization (c), crystallization followed by a second firing (c-r), crystallization with glaze in one step (cg), and crystallization followed by a glaze layer firing (c-g). Surface roughness was measured by means of a profilometer, and flexural strength was determined using a three-point bending test. Surface morphology, fractography, and crack healing analysis were conducted using scanning electron microscopy. RESULTS Refiring (c-r) did not affect the surface roughness (Ra) while applying glaze at both cg and c-g procedures increased the roughness. ALDc-g (442.3 ± 92.5 MPa) promoted higher strength than ALDcg (282.1 ± 64.4 MPa), whereas LDcg (402.9 ± 78.4 MPa) was stronger than LDc-g (255.5 ± 68.7 MPa). Refiring completely closed the crack in ALD, but it had a limited effect on LD. CONCLUSIONS Two-step crystallization and glazing improved ALD strength compared to the one-step protocol. Refiring and one-step glazing do not increase LD's strength, while two-step glazing has a negative effect. CLINICAL RELEVANCE Besides both materials being lithium-disilicate glass ceramics, the glazing technique and firing protocol affected their roughness and flexural strength differently. A two-step crystallization and glazing should be the first choice for ALD, while for LD, glazing is optional and when necessary, should be applied in one-step.
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Affiliation(s)
- Y Lu
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, The Netherlands, Gustav Mahlerlaan 3004, 1081, Amsterdam, Noord-Holland, LA, Netherlands
| | - A M O Dal Piva
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, The Netherlands, Gustav Mahlerlaan 3004, 1081, Amsterdam, Noord-Holland, LA, Netherlands.
| | - I Nedeljkovic
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, The Netherlands, Gustav Mahlerlaan 3004, 1081, Amsterdam, Noord-Holland, LA, Netherlands
| | - J P M Tribst
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, The Netherlands, Gustav Mahlerlaan 3004, 1081, Amsterdam, Noord-Holland, LA, Netherlands
- Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands, Gustav Mahlerlaan 3004, 1081, Amsterdam, Noord-Holland, LA, Netherlands
| | - A J Feilzer
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, The Netherlands, Gustav Mahlerlaan 3004, 1081, Amsterdam, Noord-Holland, LA, Netherlands
- Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands, Gustav Mahlerlaan 3004, 1081, Amsterdam, Noord-Holland, LA, Netherlands
| | - C J Kleverlaan
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, The Netherlands, Gustav Mahlerlaan 3004, 1081, Amsterdam, Noord-Holland, LA, Netherlands
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Lin F, Wang B, Zhang Y, Li S, Zhang Q, Xiao Y, Zuo Q. The effect of prolonged holding time on the mechanical property and microstructural property of lithium disilicate glass-ceramic. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2022; 33:69. [PMID: 36190565 PMCID: PMC9529710 DOI: 10.1007/s10856-022-06693-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Repeat firing produces uncertainty about stabilizing lithium disilicate glass-ceramic (LDGC) material properties, even though prolonged holding time can enhance the mechanical property of LDGC during a single firing cycle. However, the effect of prolonged holding time and repeat firing on the mechanical property and microstructure of LDGC is not fully understood. In the present study, three groups of LDGC material were created: (i) extension of holding time (7 vs. 14 vs. 28 min) at 780-800 °C; (ii) holding time extension (7 vs. 14 min) and dual sintering at 800-820 °C, respectively; (iii) dual sintering with prolonged holding time (7 vs. 14 min) at 820-840 °C. The nano-indenter test revealed that prolonged holding time (14 and 28 min) promoted the enhancement of LDGC hardness and Young's modulus. X-ray photoelectron spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy confirmed that prolonged holding time increased and stabilized LD phase in LDGC, as well as induced residual compressive stress. Scanning electron microscopy showed that prolonged holding time increased LD crystal grains homogeneously and facilitated LDGC to form dense interlocking structure without enlarging crystal size grains significantly. In contrast, LDGC that dual sintered alone at 820-840 °C possessed inferior mechanical properties, coupled with heterogeneous crystal phases, residual tensile stress, and melted crystals grains in the porous microstructure. Interestingly, these deteriorated properties of LDGC caused by dual sintering alone could be counteracted by prolonging the holding time. Nevertheless, the LDGC materials displayed an excellent biocompatibility throughout the study. This study identified that prolonged holding time during repeated firing cycles stabilized LD phase and crystal grain size of LDGC, thus enhanced the mechanical properties, which provided a new insight to extend the repeat fired restoration longevity of LDGC. Graphical abstract.
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Affiliation(s)
- Feng Lin
- Stomatological Hospital of Xiamen Medical College, Xiamen Medical College, Xiamen, PR China
- Xiamen Key Laboratory of Stomatological Disease Diagnosis and Treatment, Xiamen, PR China
- Engineering Research Center of Fujian University for Stomatological Biomaterials, Xiamen, PR China
| | - Bin Wang
- Stomatological Hospital of Xiamen Medical College, Xiamen Medical College, Xiamen, PR China
- Xiamen Key Laboratory of Stomatological Disease Diagnosis and Treatment, Xiamen, PR China
- Engineering Research Center of Fujian University for Stomatological Biomaterials, Xiamen, PR China
| | - Yanmei Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Shuigen Li
- Stomatological Hospital of Xiamen Medical College, Xiamen Medical College, Xiamen, PR China
- Xiamen Key Laboratory of Stomatological Disease Diagnosis and Treatment, Xiamen, PR China
- Engineering Research Center of Fujian University for Stomatological Biomaterials, Xiamen, PR China
| | - Qiufang Zhang
- Stomatological Hospital of Xiamen Medical College, Xiamen Medical College, Xiamen, PR China
- Xiamen Key Laboratory of Stomatological Disease Diagnosis and Treatment, Xiamen, PR China
| | - Yin Xiao
- Institute of Health and Biomedical Innovation, School of Chemistry, Physics, Mechanical Engineering, Queensland University of Technology, Brisbane, QLD, Australia.
- Australia-China Centre for Tissue Engineering and Regenerative Medicine, Brisbane, QLD, Australia.
| | - Qiliang Zuo
- Stomatological Hospital of Xiamen Medical College, Xiamen Medical College, Xiamen, PR China.
- Xiamen Key Laboratory of Stomatological Disease Diagnosis and Treatment, Xiamen, PR China.
- Engineering Research Center of Fujian University for Stomatological Biomaterials, Xiamen, PR China.
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Subaşı MG, Çakmak G, Sert M, Yilmaz B. Effect of multiple firings on surface roughness and flexural strength of CAD-CAM ceramics. J Prosthet Dent 2022; 128:216.e1-216.e8. [PMID: 35788273 DOI: 10.1016/j.prosdent.2022.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 10/17/2022]
Abstract
STATEMENT OF PROBLEM Knowledge on the effect of multiple firings on surface roughness and the flexural strength of different types of monolithic computer-aided design and computer-aided manufacturing (CAD-CAM) ceramics is limited. PURPOSE The purpose of this in vitro study was to evaluate the effect of multiple firings on the surface roughness and flexural strength of 4 different CAD-CAM ceramics after thermocycling. MATERIAL AND METHODS Four different CAD-CAM ceramics (Lava All Zirconia 3-mol yttria tetragonal zirconia polycrystal [3-YTZP] [Z], VITA SUPRINITY [S], IPS e.max CAD [EX], IPS Empress CAD [E]) (n=33) were wet-sectioned to form rectangular 18×4×1.2-mm specimens. After glaze application, the specimens were divided into 3 subgroups according to the number of firings (1, 2, and 4) (n=11). The specimens were thermocycled (10 000 cycles), and surface roughness and flexural strength values were measured (n=10). One additional specimen from each group was analyzed by using scanning electron microscopy (SEM). Data were analyzed by 2-way analysis of variance (ANOVA) and the Tukey honestly significance difference (HSD) test (α=.05). RESULTS According to the 2-way ANOVA, the material, number of firings, and the interaction between the material and number of firings affected the surface roughness (P<.001). For flexural strength, material (P<.001) and number of firings (P<.039) were found significant. Multiple firings (2 or 4 firings) affected the surface roughness of E (P<.001). Regardless of the number of firings, the Z material had the highest flexural strength (P<.001). Four firings affected the flexural strength values only for the Z material (P≤.005). CONCLUSIONS CAD-CAM ceramic type affected the surface roughness and flexural strength values. The surface roughness of E was lower when fired 2 or 4 times than when fired once. The flexural strength of Z was lower when fired 4 times than when fired once.
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Affiliation(s)
- Meryem Gülce Subaşı
- Associate Professor, Department of Prosthodontics, Kutahya Saglik Bilimleri University, Faculty of Dentistry, Kütahya, Turkey
| | - Gülce Çakmak
- Senior Research Associate, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.
| | - Murat Sert
- Assistant Professor, Department of Medical Laboratory Techniques, Ankara Yildirim Beyazit University, Ankara, Turkey
| | - Burak Yilmaz
- Associate Professor, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland; Associate Professor, 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 University College of Dentistry, Columbus, Ohio
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Sert M, Subaşı MG, Donmez MB, Çakmak G, Yilmaz B. Effect of firing cycle and aging on long-term chemical degradation of monolithic CAD-CAM ceramics. J Prosthet Dent 2022; 128:89.e1-89.e10. [PMID: 35705433 DOI: 10.1016/j.prosdent.2022.04.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 10/18/2022]
Abstract
STATEMENT OF PROBLEM Previous studies have shown the susceptibility of dental ceramics to degradation when subjected to certain media. However, knowledge on the effect of repeated firings and thermocycling on the ion elution of computer-aided design and computer-aided manufacturing (CAD-CAM) ceramics is lacking. PURPOSE The purpose of this in vitro study was to compare the effect of repeated firings on the ion elution of CAD-CAM materials before and after thermocycling. MATERIAL AND METHODS Bar-shaped specimens were prepared from 4 different CAD-CAM materials (monolithic zirconia [Z], zirconia-reinforced lithium silicate glass-ceramic [S], lithium disilicate glass-ceramic [EX], and leucite-reinforced glass-ceramic [E]) and divided into 3 groups according to the number of repeated glaze firings (1 firing [1F], 2 firings [2F], and 4 firings [4F]). Specimens were placed into deionized water (pH 7.4) and stored at 37 °C for 168 hours. Inductively coupled plasma-optic emission spectrophotometry (ICP-OES) was used to measure the baseline values of the eluted ions in immersion. The specimens were then subjected to thermocycling. Then, surface roughness (Ra) and ion elution values were measured. The Kruskal-Wallis and Mann-Whitney U tests were used to analyze the ion elution data before and after thermocycling, and the effect of thermocycling on ion elution was assessed by the Wilcoxon signed rank test. Ra data were analyzed with 2-way analysis of variance (ANOVA) and the Tukey honestly significant difference tests (α=.05). RESULTS Elution of some ions varied depending on the material-firing pair before (Al, As, B, Ba, Cr, Cu, Li, Mg, Na, P, and Zn) and after (Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cu, K, Li, Mg, Na, P, Y, and Zn) thermocycling. Before thermocycling, all firing groups within each material showed a similar number of significantly higher eluted ions. After thermocycling, the number of significantly higher eluted ions decreased in all materials, except for EX. The effect of thermocycling on the ion elution of the 1F group of Z (Al, Be, Ca, Cd, Co, Cr, Cu, K, Li, P, Y, and Zn), S (As, Be, Cd, Co, Cr, K, P, and Y), EX (B, Cu, and P), and E (B and Ba); 2F group of Z (Al, Be, Ca, Co, Cr, Cu, K, Li, P, and Y), S (Be, Cd, Co, K, Li, and Y), EX (P), and E (P); 4F group of Z (Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, K, Li, P, and Y), S (Al, Be, Cd, Co, Cr, Li, Mg, and Y), EX (Be, Ca, Cd, Co, K, Y, and Zn), and E (Ca and P) was nonsignificant (P≥.051). The interaction between material and repeated firings (P<.001) had a significant effect on Ra. For 1F groups, E showed the highest Ra (P≤.003), while Z had higher Ra than S (P=.009). For 2F groups, Z had higher Ra than S (P=.01). The differences among 4F groups were nonsignificant (P≥.677). An increased number of repeated firings (2F and 4F) decreased the Ra of E (P<.001). CONCLUSIONS The effect of repeated firings and thermocycling on the chemical stability of the tested CAD-CAM materials varied. No clear trend was observed on the elution of different ions within material-firing pairs before thermocycling. However, thermocycling increased the number of significantly higher eluted ions for EX. The effect of thermocycling on the ion elution of materials varied depending on ions. Repeated firings decreased the surface roughness of E.
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Affiliation(s)
- Murat Sert
- Assistant Professor, Department of Medical Laboratory Techniques, Ankara Yildirim Beyazit University, Ankara, Turkey
| | - Meryem Gülce Subaşı
- Associate Professor, Department of Prosthodontics, Kütahya Health Sciences University, Faculty of Dentistry, Kütahya, Turkey
| | - Mustafa Borga Donmez
- Assistant Professor, Department of Prosthodontics, Istinye University, Faculty of Dentistry, Istanbul, Turkey; Visiting Researcher, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland
| | - Gülce Çakmak
- Senior Research Associate, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.
| | - Burak Yilmaz
- Associate Professor, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland; Associate Professor, 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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Jurado CA, El-Gendy T, Hyer J, Tsujimoto A. Color stability of fully- and pre-crystalized chair-side CAD-CAM lithium disilicate restorations after required and additional sintering processes. J Adv Prosthodont 2022; 14:56-62. [PMID: 35284052 PMCID: PMC8891683 DOI: 10.4047/jap.2022.14.1.56] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/22/2022] [Accepted: 01/25/2022] [Indexed: 11/30/2022] Open
Abstract
PURPOSE The aim of this study was to investigate shade changes in fully- and pre-crystalized CAD-CAM lithium disilicate crowns after the required and additional firing processes. MATERIALS AND METHODS One hundred and five crowns of shade A1 with high translucency were milled out of CAD-CAM lithium disilicate blocks and categorized as follows (n = 15): (1) restorations fabricated from Straumann n!ce with no additional sintering process; (2) restorations fabricated from Straumann n!ce with one additional sintering process; (3) restorations fabricated from Straumann n!ce with two additional sintering processes; (4) restorations fabricated from Amber Mill with one sintering process; (5) restorations fabricated from Amber Mill with two sintering processes; (6) restorations fabricated from IPS e.max CAD with one sintering process; (7) restorations fabricated from IPS e.max CAD with two sintering processes. All restorations were evaluated with a color imaging spectrophotometer. RESULTS All restorations presented some color alteration from the original shade both after a single and after two firing processes. CONCLUSION The required and additional sintering processes for restorations fabricated with chairside CAD-CAM lithium disilicate blocks cause an alteration of the original shade selected. Shade A1 high translucency restorations tend to change to a more yellowish B1 shade after a sintering process.
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Affiliation(s)
- Carlos Alberto Jurado
- Texas Tech University Health Sciences Center El Paso Woody L. Hunt School of Dental Medicine, El Paso, TX, USA
| | - Tamer El-Gendy
- A. T. Still University Arizona School of Dentistry and Oral Health, Mesa, AZ, USA
| | - Jared Hyer
- A. T. Still University Arizona School of Dentistry and Oral Health, Mesa, AZ, USA
| | - Akimasa Tsujimoto
- Department of Operative Dentistry, University of Iowa College of Dentistry, Iowa City, IA, USA
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