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Moreira PM, Carvalho GLM, de Castro Albuquerque R, André CB. Effect of hydrofluoric acid and self-etch ceramic primers on the flexural strength and fatigue resistance of glass ceramics: A systematic review and meta-analysis of in vitro studies. JAPANESE DENTAL SCIENCE REVIEW 2024; 60:198-210. [PMID: 39027733 PMCID: PMC11254839 DOI: 10.1016/j.jdsr.2024.06.001] [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: 10/02/2023] [Revised: 05/06/2024] [Accepted: 06/04/2024] [Indexed: 07/20/2024] Open
Abstract
This systematic review evaluated the effect of different hydrofluoric acid (HF) etching regimens and a self-etch ceramic primer (SECP) on the flexural strength (FS) and fatigue failure load (FFL) of glass-ceramic materials.The identification of relevant studies was conducted by two authors in five databases: PubMED, Scopus, Web Of Science, LILACS and Virtual Health Library (BVS) until July 2022 with no year limit. The analysis was conducted in RevMan 5.4.1 Software (Cochrane Collaboration) using Random effect model at 5 %. The risk of bias of the included studies were assessed. From the 5349 articles identified, 34 were included for quantitative analysis. Meta-analysis showed that for predominantly glassy ceramics, etching with HF 5 % had no significant impact on FS, however, HF acid etching with concentrations greater than 5 % negatively impacted FS. For lithium disilicate glass-ceramics (LDGC) HF acid etching, negatively influenced FS, while increasing the FFL. HF etching negatively affected FS of hybrid ceramics. The self-etch ceramic primer and HF acid etching showed a similar impact on FFL and FS. This meta-analysis indicates that the impact of SECP and HF acid etching on the mechanical behavior of glass ceramics is material-dependent.
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Affiliation(s)
- Paulo Matias Moreira
- Department of Restorative Dentistry, School of Dentistry, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | | | - Rodrigo de Castro Albuquerque
- Department of Restorative Dentistry, School of Dentistry, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Carolina Bosso André
- Department of Restorative Dentistry, School of Dentistry, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
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Souza LFB, Teixeira KF, Cadore-Rodrigues AC, Pires TDS, Valandro LF, Moraes RR, Özcan M, Pereira GKR. Evaluating mechanical and surface properties of zirconia-containing composites: 3D printing, subtractive, and layering techniques. J Mech Behav Biomed Mater 2024; 157:106608. [PMID: 38833781 DOI: 10.1016/j.jmbbm.2024.106608] [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: 03/05/2024] [Revised: 05/01/2024] [Accepted: 05/29/2024] [Indexed: 06/06/2024]
Abstract
This study assessed the monotonic and fatigue flexural strength (FS), elastic modulus (E), and surface characteristics of a 3D printed zirconia-containing resin composite compared to subtractive and conventional layering methods. Specimens, including discs (n = 15; Ø = 15 mm × 1.2 mm) and bars (n = 15; 14 × 4 × 1.2 mm), were prepared and categorized into three groups: 3D printing (3D printing - PriZma 3D Bio Crown, Makertech), Subtractive (Lava Ultimate blocks, 3M), and Layering (Filtek Z350 XT, 3M). Monotonic tests were performed on the discs using a piston-on-three-balls setup, while fatigue tests employed similar parameters with a frequency of 10 Hz, initial stress at 20 MPa, and stress increments every 5000 cycles. The E was determined through three-point-bending test using bars. Surface roughness, fractographic, and topographic analyses were conducted. Statistical analyses included One-way ANOVA for monotonic FS and roughness, Kruskal-Wallis for E, and Kaplan-Meier with post-hoc Mantel-Cox and Weibull analysis for fatigue strength. Results revealed higher monotonic strength in the Subtractive group compared to 3D printing (p = 0.02) and Layering (p = 0.04), while 3D Printing and Layering exhibited similarities (p = 0.88). Fatigue data indicated significant differences across all groups (3D Printing < Layering < Subtractive; p = 0.00 and p = 0.04, respectively). Mechanical reliability was comparable across groups. 3D printing and Subtractive demonstrated similar E, both surpassing Layering. Moreover, 3D printing exhibited higher surface roughness than Subtractive and Layering (p < 0.05). Fractographic analysis indicated that fractures initiated at surface defects located in the area subjected to tensile stress concentration. A porous surface was observed in the 3D Printing group and a more compact surface in Subtractive and Layering methods. This study distinguishes the unique properties of 3D printed resin when compared to conventional layering and subtractive methods for resin-based materials. 3D printed shows comparable monotonic strength to layering but lags behind in fatigue strength, with subtractive resin demonstrating superior performance. Both 3D printed and subtractive exhibit similar elastic moduli, surpassing layering. However, 3D printed resin displays higher surface roughness compared to subtractive and layering methods. The study suggests a need for improvement in the mechanical performance of 3D printed material.
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Affiliation(s)
- Luiza Freitas Brum Souza
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Kétlin Fagundes Teixeira
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Ana Carolina Cadore-Rodrigues
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Telma de Souza Pires
- Faculty of Dentistry, 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 Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil; Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Rafael R Moraes
- School of Dentistry, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
| | - Mutlu Özcan
- Clinic for Masticatory Disorders and Dental Biomaterials, Center for Dental Medicine, University of Zurich, 8032, Zurich, Switzerland.
| | - Gabriel Kalil Rocha Pereira
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil; Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
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Lenz U, Santos RB, Griggs JA, Estrela C, Bueno MDR, Porto OCL, Della Bona A. Longevity of different abutments placed on narrow diameter implants: Assessment of structural damage and loosening. Dent Mater 2024; 40:1332-1340. [PMID: 38876825 DOI: 10.1016/j.dental.2024.06.003] [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: 12/27/2023] [Revised: 05/29/2024] [Accepted: 06/03/2024] [Indexed: 06/16/2024]
Abstract
OBJECTIVES To evaluate structural damage and loosening of abutments placed on narrow diameter implants after cyclic fatigue. METHODS Sixty Morse taper narrow diameter implants (Neodent, Brazil) received two types of abutments (1PA- one-piece abutment or 2PA- two-piece abutment), which were randomly divided into 3 fatigue experiments (n = 10). The implants were placed into a customized supporting holder and a software-assisted digital torque wrench secured the manufacturer recommended torque for each abutment. Cone beam computed tomography (CBCT) scans were acquired, before and after fatigue, and post-processed (software e-Vol DX) to assess damage and abutment displacement. The boundary fatigue method was adapted to use 2 × 106 cycles, 2 Hz of frequency and constant peak load of 80 N (first experiment) that varied according to the failure rate of previous specimens (second and third experiments). Failure was evaluated using CBCT scans and removal torque values. Data were used to estimate long-term torque degradation, probability of failure and Weibull modulus (software ALTA PRO9). RESULTS All 2PA specimens became loosen independently of the applied fatigue load, and structural bending was observed in 14 abutments. Eight 1PA got loosen during the fatigue experiment. The Weibull analysis showed a lower modulus (m = 1.0; 0.7, 1.4) for 1PA than for 2PA (m = 2.6; 2, 3.4) resulting in longer predicted lifetimes and slower torque degradation for 1PA than for 2PA specimens. SIGNIFICANCE 1PA showed greater long-term survival probability than 2PA. Predicting the lifetime and mechanical behavior of implant-abutment systems are useful information to clinicians during the decision-making process of oral rehabilitations.
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Affiliation(s)
- Ulysses Lenz
- Postgraduate Program in Dentistry, School of Dentistry, University of Passo Fundo, Passo Fundo, RS, Brazil
| | - Renan Brandenburg Santos
- Postgraduate Program in Dentistry, School of Dentistry, University of Passo Fundo, Passo Fundo, RS, Brazil
| | - Jason Alan Griggs
- Department of Biomedical Materials Science, University of Mississippi Medical Center, MS, USA
| | - Carlos Estrela
- School of Dentistry, Federal University of Goiás, Goiânia, GO, Brazil
| | | | | | - Alvaro Della Bona
- Postgraduate Program in Dentistry, School of Dentistry, University of Passo Fundo, Passo Fundo, RS, Brazil.
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Cantelli V, Meirelles MT, Della Bona A. Fatigue methods for evaluating translucent dental zirconia. J Dent 2024; 148:105242. [PMID: 39009334 DOI: 10.1016/j.jdent.2024.105242] [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: 06/09/2024] [Revised: 07/11/2024] [Accepted: 07/12/2024] [Indexed: 07/17/2024] Open
Abstract
OBJECTIVE To investigate fatigue methods for the evaluation of translucent zirconia and to associate in vitro failures with clinically reported ones. DATA Studies published in English that used fatigue tests on dental translucent zirconia. SOURCES Two databases (MEDLINE/PubMed and Scopus) were electronically searched without any restriction on year of publication. STUDY SELECTION A total of 4555 studies were identified. After removal of duplicates (78) and irrelevant articles (4316) that did not meet the inclusion criteria, 161 articles were considered eligible based on their titles and abstracts. These articles were fully read, leading to the inclusion of 41 studies in the review. RESULTS The most widely used fatigue method for evaluation of translucent zirconia was step-stress (18 articles), followed by staircase (seven articles), and step-wise (two articles). Most studies had been conducted in a wet environment with the use of a stainless steel piston to apply load to cemented structures on a dentin-like substrate. Most fracture analyses indicated the fracture originated on the cementation or contact surface where the load was applied. Moreover, studies that utilized anatomical structures (dental crowns) reported fractures starting at the cervical margin of the crowns. CONCLUSION Most studies used the step-stress method. Only three studies reported failures similar to those found in clinical trials that used translucent zirconia restorations. CLINICAL SIGNIFICANCE The study findings can assist on correlating clinical failures to the ones observed in vitro.
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Affiliation(s)
- Viviane Cantelli
- Post-graduate Program in Dentistry, School of Dentistry, University of Passo Fundo, Passo Fundo, RS, Brazil
| | - Marcelo Tapparo Meirelles
- Graduate Program in Dentistry, School of Dentistry, University of Passo Fundo, Passo Fundo, RS, Brazil
| | - Alvaro Della Bona
- Post-graduate Program in Dentistry, School of Dentistry, University of Passo Fundo, Passo Fundo, RS, Brazil.
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Pilecco RO, da Rosa LS, Baldi A, Machry RV, Tribst JPM, Valandro LF, Kleverlaan CJ, Scotti N, Pereira GKR. How do different intraoral scanners and milling machines affect the fit and fatigue behavior of lithium disilicate and resin composite endocrowns? J Mech Behav Biomed Mater 2024; 155:106557. [PMID: 38657286 DOI: 10.1016/j.jmbbm.2024.106557] [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: 02/27/2024] [Revised: 04/03/2024] [Accepted: 04/17/2024] [Indexed: 04/26/2024]
Abstract
The aim of this in vitro study was to evaluate the effect of the combinations of two different intraoral scanners (IOS), two milling machines, and two restorative materials on the marginal/internal fit and fatigue behavior of endocrowns produced by CAD-CAM. Eight groups (n= 10) were considered through the combination of TRIOS 3 (TR) or Primescan (PS) IOS; 4-axes (CR; CEREC MC XL) or 5-axes (PM; PrograMill PM7) milling machines; and lithium disilicate (LD; IPS e.max CAD) or resin composite (RC; Tetric CAD) restorative materials. Specific surface treatments were applied to each material, and the bonding to its corresponding Endocrown-shaped fiberglass-reinforced epoxy resin preparations was performed (Variolink Esthetic DC). Computed microtomography (μCT) was performed to assess the marginal/internal fit, as well as a mechanical fatigue test (20 Hz, initial load = 100 N/5000 cycles; step-size = 50 N/10,000 cycles until a threshold of 1500 N, then, the step-size was increased if needed to 100 N/10,000 cycles until failure or a threshold of 2800 N) to evaluate the restorations long-term behavior. Complementary analysis of the fracture features and surface topography in scanning electron microscopy was performed. Three-way ANOVA and Kaplan-Meier test (α = 0.05) were performed for marginal/internal fit, and fatigue behavior data, respectively. PS scanner, CR milling machine, and RC endocrowns resulted in a better marginal fit compared to their counterparts. Still, the PM machine resulted in a better pulpal space fit compared to the CR milling machine. Regardless of the scanner and milling machine, RC endocrowns exhibited superior fatigue behavior than LD ones. LD endocrowns presented margin chipping regardless of the milling machine used. Despite minor differences in terms of fit, the 'IOS' and 'milling machine' factors did not impair the fatigue behavior of endocrowns. Resin-composite restorations resulted in a higher survival rate compared to glass-ceramic ones, independently of the digital devices used in the workflow.
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Affiliation(s)
- Rafaela Oliveira Pilecco
- Post-Graduate Program in Oral Sciences (Prosthodontics Units), Faculty of Dentistry, Universidade Federal de Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Lucas Saldanha da Rosa
- Post-Graduate Program in Oral Sciences (Prosthodontics Units), Faculty of Dentistry, Universidade Federal de Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Andrea Baldi
- Department of Surgical Sciences, Dental School, University of Turin (UNITO), Turin, Piedmont, Italy.
| | - Renan Vaz Machry
- Post-Graduate Program in Oral Sciences (Prosthodontics Units), Faculty of Dentistry, Universidade Federal de Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - João Paulo Mendes Tribst
- Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, North Holland, the Netherlands.
| | - Luiz Felipe Valandro
- Post-Graduate Program in Oral Sciences (Prosthodontics Units), Faculty of Dentistry, Universidade Federal de Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Cornelis Johannes Kleverlaan
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, North Holland, the Netherlands.
| | - Nicola Scotti
- Department of Surgical Sciences, Dental School, University of Turin (UNITO), Turin, Piedmont, Italy.
| | - Gabriel Kalil Rocha Pereira
- Post-Graduate Program in Oral Sciences (Prosthodontics Units), Faculty of Dentistry, Universidade Federal de Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
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Krug R, Droste L, Schreiber C, Reichardt E, Krastl G, Hahn B, Soliman S. Long-term performance of ceramic in/-onlays vs. cast gold partial crowns - a retrospective clinical study. Clin Oral Investig 2024; 28:298. [PMID: 38702521 PMCID: PMC11068672 DOI: 10.1007/s00784-024-05682-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 04/22/2024] [Indexed: 05/06/2024]
Abstract
OBJECTIVES To assess the long-term clinical performance of ceramic in-/onlays (CIOs) and cast gold partial crowns (CGPCs) in posterior teeth in terms of success, survival, complications (biological, technical) and quality. MATERIAL AND METHODS In a retrospective study, a total of 325 patients were recorded after up to 24.8 years (mean 13.9 ± 3.8 years) having (pre-)molars restored with CIO (Empress I, Ivoclar Vivadent, n = 161) and CGPC (Degunorm, DeguDent, n = 164) by supervised undergraduate students. A total of 296 restorations were assessed clinically and radiologically in healthy and endodontically treated teeth using modified United States Public Health Service (USPHS) criteria. Cumulative success and survival rates of the restorations were calculated using Kaplan-Meier estimates. Biological and technical complications were recorded. Status of oral health comprising caries risk and localized periodontitis were assessed. RESULTS The cumulative success rates of CIOs were 92.1% and of CGPCs 84.2% after mean service times of 14.5 years. The annual failure rates of total service times were 0.5% in teeth restored with CIO (n = 155) and 0.7% in teeth restored with CGPC (n = 163). The cumulative survival rates of CIOs were 93.9% after a mean service time of 15.2 years and decreased to 91.7% after 23.5 years. The cumulative survival rates of CGPCs were 92.6% after a mean service time of 14.9 years and 91.8% after 23.5 years. Complications in CIOs (n = 149) were ceramic fracture (6.7%), secondary caries (4.7%), endodontic complication (2.7%) and tooth fracture (1.3%) compared to CGPCs (n = 147) with endodontic complication (8.8%), secondary caries (4.8%) and decementation (2.0%). Endodontically treated teeth restored with CIO or CGPC revealed significantly less often success compared with corresponding vital teeth (p = .02). CIOs and CGPCs revealed clinically and radiographically good and excellent qualities with 71.8% (107/149) and 68% (100/147) without any significant differences regarding type of restoration. CONCLUSIONS Both CIOs and CGPCs achieved high survival rates up to 24.8 years when performed by supervised undergraduate students. The longevity of the restorations may benefit from the intraoral repair of accessible defects and, in case of pulp infection or necrosis, an adequate endodontic management. CLINICAL RELEVANCE CIOs and CGPCs made by supervised undergraduate students are proper restoration types in posterior teeth in the long-term. An adequate preparation design, meticulous care in the inserting technique and constant biofilm removal due to proper oral hygiene combined with professional maintenance care are substantial. The clinical long-term performance was mostly limited by ceramic fractures in CIOs and endodontic complications in CGPCs.
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Affiliation(s)
- Ralf Krug
- Department of Conservative Dentistry and Periodontology and Center of Dental Traumatology, University Hospital of Würzburg, Würzburg, Germany.
| | | | | | | | - Gabriel Krastl
- Department of Conservative Dentistry and Periodontology and Center of Dental Traumatology, University Hospital of Würzburg, Würzburg, Germany
| | - Britta Hahn
- Department of Conservative Dentistry and Periodontology and Center of Dental Traumatology, University Hospital of Würzburg, Würzburg, Germany
| | - Sebastian Soliman
- Department of Conservative Dentistry and Periodontology and Center of Dental Traumatology, University Hospital of Würzburg, Würzburg, Germany
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Lohbauer U, Fabris DCN, Lubauer J, Abdelmaseh S, Cicconi MR, Hurle K, de Ligny D, Goetz-Neunhoeffer F, Belli R. Glass science behind lithium silicate glass-ceramics. Dent Mater 2024; 40:842-857. [PMID: 38580561 DOI: 10.1016/j.dental.2024.03.006] [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: 12/20/2023] [Revised: 03/28/2024] [Accepted: 03/29/2024] [Indexed: 04/07/2024]
Abstract
OBJECTIVES Lithium silicate-based glass ceramics have evolved as a paramount restorative material in restorative and prosthetic dentistry, exhibiting outstanding esthetic and mechanical performance. Along with subtractive machining techniques, this material class has conquered the market and satisfied the patients' needs for a long-lasting, excellent, and metal-free alternative for single tooth replacements and even smaller bridgework. Despite the popularity, not much is known about the material chemistry, microstructure and terminal behaviour. METHODS This article combines a set of own experimental data with extensive review of data from literature and other resources. Starting at manufacturer claims on unique selling propositions, properties, and microstructural features, the aim is to validate those claims, based on glass science. Deep knowledge is mandatory for understanding the microstructure evolution during the glass ceramic process. RESULTS Fundamental glass characteristics have been addressed, leading to formation of time-temperature-transformation (TTT) diagrams, which are the basis for kinetic description of the glass ceramic process. Nucleation and crystallization kinetics are outlined in this contribution as well as analytical methods to describe the crystalline fraction and composition qualitatively and quantitatively. In relation to microstructure, the mechanical performance of lithium silicate-based glass ceramics has been investigated with focus on fracture strength versus fracture toughness as relevant clinical predictors. CONCLUSION Fracture toughness has been found to be a stronger link to initially outlined manufacturer claims, and to more precisely match ISO recommendations for clinical indications.
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Affiliation(s)
- Ulrich Lohbauer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Zahnklinik 1 - Zahnerhaltung und Parodontologie, Forschungslabor für dentale Biomaterialien, Glueckstrasse 11, 91054 Erlangen, Germany.
| | - Débora Cristina Niero Fabris
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Zahnklinik 1 - Zahnerhaltung und Parodontologie, Forschungslabor für dentale Biomaterialien, Glueckstrasse 11, 91054 Erlangen, Germany
| | - Julia Lubauer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Zahnklinik 1 - Zahnerhaltung und Parodontologie, Forschungslabor für dentale Biomaterialien, Glueckstrasse 11, 91054 Erlangen, Germany
| | - Samuel Abdelmaseh
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department Werkstoffwissenschaften, Institut für Glas und Keramik, Martensstrasse 5, 91058 Erlangen, Germany
| | - Maria-Rita Cicconi
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department Werkstoffwissenschaften, Institut für Glas und Keramik, Martensstrasse 5, 91058 Erlangen, Germany
| | - Katrin Hurle
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), GeoZentrum Nordbayern, Mineralogy, Schlossgarten 5a, 91054 Erlangen, Germany
| | - Dominique de Ligny
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department Werkstoffwissenschaften, Institut für Glas und Keramik, Martensstrasse 5, 91058 Erlangen, Germany
| | - Friedlinde Goetz-Neunhoeffer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), GeoZentrum Nordbayern, Mineralogy, Schlossgarten 5a, 91054 Erlangen, Germany
| | - Renan Belli
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Zahnklinik 1 - Zahnerhaltung und Parodontologie, Forschungslabor für dentale Biomaterialien, Glueckstrasse 11, 91054 Erlangen, Germany
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Pérez JA, Rodríguez-Rojas F, Borrero-López Ó, Sánchez-González E. Effect of Post-Processing Heat Treatment on Micro-Contact Damage of Zirconia-Reinforced Lithium Silicate Dental Materials. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1961. [PMID: 38730767 PMCID: PMC11084880 DOI: 10.3390/ma17091961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 05/13/2024]
Abstract
Zirconia-reinforced lithium silicate (ZLS) is utilized as a material for prosthetic tooth crowns, offering enhanced strength compared to other dental glass-ceramics. In this study, we investigate a commercial ZLS material, provided in a fully crystallized form. We examine the effects of an optional post-processing heat treatment on micro-contact damage using controlled indentation tests simulating the primary modes of contact during chewing: axial and sliding. Our findings indicate that the heat treatment does not affect mechanical properties such as the elastic modulus, hardness and indentation fracture toughness. However, it does enhance the resistance to contact damage by fracture and chipping in both axial and sliding modes, as well as the resistance to crack initiation measured from sliding tests. This improvement is attributed to the refinement of the flaw population achieved through the heat treatment. The results are analysed using principles of contact and fracture mechanics theory, discussing their significance in prosthetic dentistry.
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Affiliation(s)
| | | | | | - Estíbaliz Sánchez-González
- Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura, 06006 Badajoz, Spain; (J.A.P.); (F.R.-R.); (Ó.B.-L.)
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9
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Chai H, Russ J, Vardhaman S, Lim CH, Zhang Y. A Bilayer Method for Measuring Toughness and Strength of Dental Ceramics. J Dent Res 2024; 103:419-426. [PMID: 38410925 DOI: 10.1177/00220345231225445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024] Open
Abstract
The ever-increasing usage of ceramic materials in restorative dentistry necessitates a simple and effective method to evaluate flexural strength σF and fracture toughness KC. We propose a novel method to determine these quantities using a bilayer specimen composed of a brittle plate adhesively bonded onto a transparent polycarbonate substrate. When this bilayer structure is placed under spherical indentation, tunneling radial cracks initiate and propagate in the lower surface of the brittle layer. The failure analysis is based on previous theoretical relationships, which correlate σF with the indentation force P and layer thickness d, and KC with P and mean length of radial cracks. This work examines the accuracy and limitations of this approach using a wide range of contemporary dental ceramic materials. The effect of layer thickness, indenter radius, load level, and length and number of radial cracks are carefully examined. The accuracy of the predicted σF and KC is similar to those obtained with other concurrent test methods, such as biaxial flexure and 3-point bending (σF), and bending specimens with crack-initiation flaws (KC). The benefits of the present approach include treatment for small and thin plates, elimination of the need to introduce a precrack, and avoidance of dealing with local material nonlinearity effects for the KC measurements. Finally, the bilayer configuration resembles occlusal loading of a ceramic restoration (brittle layer) bonded to a posterior tooth (compliant substrate).
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Affiliation(s)
- H Chai
- School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
| | - J Russ
- School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - S Vardhaman
- Department of Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA, USA
- College of Dental Medicine, Columbia University, New York, NY, USA
| | - C H Lim
- Department of Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA, USA
| | - Y Zhang
- Department of Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA, USA
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10
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Pilecco RO, Machry RV, Ribeiro VF, Dal Piva AMDO, Tribst JPM, Kleverlaan CJ, Moraes RR, Pereira GKR. Impact of try-in paste removal on the fatigue behavior of bonded lithium disilicate ceramics. J Mech Behav Biomed Mater 2024; 151:106394. [PMID: 38218045 DOI: 10.1016/j.jmbbm.2024.106394] [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: 12/11/2023] [Revised: 01/06/2024] [Accepted: 01/07/2024] [Indexed: 01/15/2024]
Abstract
This in vitro study assessed the effectiveness of three cleaning protocols (air-water spray, 37% phosphoric acid, or Ivoclean) on lithium disilicate restorations' fatigue behavior after try-in paste application, compared to a clean condition. Lithium disilicate discs (IPS e.max CAD, Ivoclar) with Ø-= 12 mm and 1 mm thickness were prepared from prefabricated CAD-CAM blocks, polished, subjected to CAD-CAM milling topography simulation and crystallization. After, etching with 5% hydrofluoric acid and the application of try-in paste (Variolink try-in paste shade white; load of 2.5 N for 5 min) was performed. Discs that received try-in paste were divided into three groups according to the removal protocol: SPRAY - air-water spray for 30 s; HPO - active application of 37% phosphoric acid for 60 s; IVOC - application of Ivoclean for 20 s. Control group (CTRL group) did not receive the try-in paste application. Half of the specimens (n= 15) were tested in the baseline condition (24 h up to 7 days), and the others underwent 25,000 thermal cycles (5 - 55 °C) + 210 days of distilled water storage (37 °C). Additional specimens (n= 3) underwent monotonic testing (1 mm/min). Fatigue testing involved a cyclic fatigue approach (20 Hz, initial load = 100 N - 5000 cycles, step size = 50 N - 10,000 cycles) until a visible crack appeared. Fractographic and topographic analyses were performed. Fatigue data were statistically analyzed with two-way ANOVA, Kaplan-Meier log-rank (Mantel-Cox), and independent t-test (α= 0.05). In the baseline condition, the IVOC group resulted in a superior fatigue behavior compared to the CTRL and SPRAY groups, but similar to the HPO group. The HPO and SPRAY presented a similar fatigue behavior to the CTRL group. It was noticed a decrease in fatigue behavior after aging, which resulted in all the cleaning protocols leading to similar fatigue behavior compared to the CTRL group. On the SPRAY group surface, try-in pastes remnants were noticed. In summary, despite a detrimental impact at baseline conditions, all tested cleaning protocols seem proper to remove the try-in paste from the ceramic's surface in the long-term evaluation.
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Affiliation(s)
- Rafaela Oliveira Pilecco
- Post-Graduate Program in Oral Sciences, Center for Development of Advanced Materials, Division of Prosthodontics-Biomaterials, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil.
| | - Renan Vaz Machry
- Post-Graduate Program in Oral Sciences, Center for Development of Advanced Materials, Division of Prosthodontics-Biomaterials, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil.
| | | | - Amanda Maria de Oliveira Dal Piva
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam en Vrije Universiteit, Amsterdam, the Netherlands.
| | - João Paulo Mendes Tribst
- Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam en Vrije Universiteit, Amsterdam, the Netherlands.
| | - Cornelis Johannes Kleverlaan
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam en Vrije Universiteit, Amsterdam, the Netherlands.
| | - Rafael R Moraes
- Graduate Program in Dentistry, Universidade Federal de Pelotas (UFPel), Pelotas, RS, Brazil.
| | - Gabriel Kalil Rocha Pereira
- Post-Graduate Program in Oral Sciences, Center for Development of Advanced Materials, Division of Prosthodontics-Biomaterials, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil.
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11
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da Rosa LS, Pilecco RO, Soares PM, Rippe MP, Pereira GKR, Valandro LF, Kleverlaan CJ, Feilzer AJ, Tribst JPM. Repair protocols for indirect monolithic restorations: a literature review. PeerJ 2024; 12:e16942. [PMID: 38406292 PMCID: PMC10893862 DOI: 10.7717/peerj.16942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 01/23/2024] [Indexed: 02/27/2024] Open
Abstract
Despite the advancements in indirect monolithic restorations, technical complications may occur during function. To overcome this issues, intraoral repair using resin composite is a practical and low-cost procedure, being able to increase the restoration's longevity. This review aimed to evaluate the need for repair and suggest a standardized repair protocol to the main indirect restorative materials. For this, studies were surveyed from PubMed with no language or date restriction, to investigate the scientific evidence of indirect monolithic restoration repair with direct resin composite. A classification to guide clinical decisions was made based on the FDI World Dental Federation criteria about defective indirect restorations considering esthetic and functional standards, along with the patient's view, to decide when polishing, repairing or replacing a defective restoration. Based on 38 surveyed studies, different resin composite intraoral repair protocols, that included mechanical and chemical aspects, were defined depending on the substrate considering resin-based, glass-ceramic or zirconia restorations. The presented criteria and protocols were developed to guide the clinician's decision-making process regarding defective indirect monolithic restorations, prolonging longevity and increasing clinical success.
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Affiliation(s)
| | | | | | | | | | | | - Cornelis Johannes Kleverlaan
- Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam en Vrije Universiteit, Amsterdam, the Netherlands
| | - Albert J. Feilzer
- Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam en Vrije Universiteit, Amsterdam, the Netherlands
| | - João Paulo Mendes Tribst
- Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam en Vrije Universiteit, Amsterdam, the Netherlands
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12
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Benalcazar Jalkh EB, Ramalho IS, Bergamo ETP, Alves LMM, Tanaka R, Witek L, Coelho PG, Hirata R, Bonfante EA. Ultrathin lithium disilicate and translucent zirconia crowns for posterior teeth: Survival and failure modes. J ESTHET RESTOR DENT 2024; 36:381-390. [PMID: 37676053 DOI: 10.1111/jerd.13127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/07/2023] [Accepted: 08/10/2023] [Indexed: 09/08/2023]
Abstract
PURPOSE To evaluate the reliability and failure modes of ultrathin (0.5 mm) lithium disilicate, translucent and ultra-translucent zirconia crowns for posterior teeth restorations. MATERIALS AND METHODS Fifty-four mandibular first molar crowns of three ceramic materials: (1) Lithium disilicate (e.max CAD, Ivoclar Vivadent), (2) 3Y-TZP (Zirconn Translucent, Vipi), and (3) 5Y-PSZ (Cercon XT, Dentsply Sirona), with 0.5 mm of thickness were milled and cemented onto composite resin abutments. Eighteen samples of each group were tested under mouth-motion step-stress accelerated life testing in a humid environment using mild, moderate, and aggressive profiles. Data was subjected to Weibull statistics. Use level curves were plotted and reliability was calculated for a given mission of 100,000 cycles at 100, 200, and 300 N. Fractographic analyses of representative samples were performed in scanning electron microscope. RESULTS Beta (β) values suggest that failures were dictated by material's strength for lithium disilicate and by fatigue damage accumulation for both zirconias. No significant differences were detected in Weibull modulus and characteristic strength among groups. At a given mission of 100,000 cycles at 100 N, lithium disilicate presented higher reliability (98% CB: 95-99) regarding 3Y-TZP and 5Y-PSZ groups (84% CB: 65%-93% and 79% CB: 37&-94%, respectively). At 200 N, lithium disilicate reliability (82% CB: 66%-91%) was higher than 5Y-PSZ (20% CB: 4%-44%) and not significantly different from 3Y-TZP (54% CB: 32%-72%). Furthermore, at 300 N no significant differences in reliability were detected among groups, with a notable reduction in the reliability of all materials. Fractographic analyses showed that crack initiated at the interface between the composite core and the ceramic crowns due to tensile stress generated at the intaglio surface. CONCLUSIONS Ultrathin lithium disilicate crowns demonstrated higher reliability relative to zirconia crowns at functional loads. Lithium disilicate and zirconia crown's reliability decreased significantly for missions at higher loads and similar failure modes were observed regardless of crown material. The indication of 0.5 mm thickness crowns in high-load bearing regions must be carefully evaluated. CLINICAL SIGNIFICANCE Ultraconservative lithium disilicate and zirconia crowns of 0.5 mm thickness may be indicated in anterior restorations and pre-molars. Their clinical indication in high-load requirement regions must be carefully evaluated.
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Affiliation(s)
- Ernesto B Benalcazar Jalkh
- Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Ilana S Ramalho
- Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Edmara T P Bergamo
- Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
- Biomaterials Division, New York University College of Dentistry, New York, New York, USA
- Department of Prosthodontics, New York University College of Dentistry, New York, New York, USA
| | - Larissa M M Alves
- Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | | | - Lukasz Witek
- Biomaterials Division, New York University College of Dentistry, New York, New York, USA
- Department of Biomedical Engineering, New York Univeristy Tandon School of Engineering, Brooklyn, New York, USA
| | - Paulo G Coelho
- DeWitt Daughtry Family Department of Surgery, Division of Plastic Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Ronaldo Hirata
- Biomaterials Division, New York University College of Dentistry, New York, New York, USA
| | - Estevam A Bonfante
- Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
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13
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Benalcazar-Jalkh EB, Cunha VS, Bergamo ETP, Alves LMM, de Monteiro-Sousa RS, Campos TMB, Tanaka R, Marcolino GDA, Souza FMD, Bonfante EA. Finishing technique effect on strength of zirconia-reinforced lithium silicate ceramic. Eur J Oral Sci 2024; 132:e12964. [PMID: 38062529 DOI: 10.1111/eos.12964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 11/14/2023] [Indexed: 01/25/2024]
Abstract
The aim of this study was to evaluate the effect of two finishing techniques, glazing or polishing, in comparison with the as-cut condition, on the biaxial-flexural-strength (BFS) of a zirconia-reinforced lithium silicate ceramic (ZLS). Cylinders were milled from CAD/CAM blocks and sliced to obtain disc-shaped specimens (ISO6872:2015). Polished and glazed specimens were processed following the manufacturer's instructions. Thirty-three specimens were obtained for each condition and microstructural and BFS/fractographic characterizations were performed. BFS and roughness data were analyzed using Weibull statistics and ANOVA one-way with Tukey post-hoc test, respectively. While a rougher surface was observed for as-cut specimens, smoother surfaces were observed for polished and glazed ZLS at microscopical evaluation and confirmed through surface-roughness evaluation. X-ray spectra depicted a glass phase for all groups and characteristic metasilicate, lithium disilicate, and lithium phosphate peaks for the as-cut and polished specimens. Glazed specimens showed higher characteristic strength than polished and as-cut specimens, which did not differ significantly. While higher Weibull-modulus was observed for the polished than for the as-cut specimens, no statistically significant differences were noted between glazed and polished, and between glazed and as-cut specimens. ZLS presents higher strength when glazed, and polishing increases the structural reliability of the material relative to the as-cut condition. Both finishing techniques reduced surface roughness similarly.
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Affiliation(s)
| | - Verena Souza Cunha
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Sao Paulo, Brazil
| | - Edmara Tatiely Pedroso Bergamo
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Sao Paulo, Brazil
- Biomaterials Division, NYU Dentistry, New York, USA
- Department of Prosthodontics, NYU Dentistry, New York, USA
| | - Larissa Marcia Martins Alves
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Sao Paulo, Brazil
| | | | - Tiago Moreira Bastos Campos
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Sao Paulo, Brazil
| | | | - Giovana de Assis Marcolino
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Sao Paulo, Brazil
| | - Felipe Machado de Souza
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Sao Paulo, Brazil
| | - Estevam Augusto Bonfante
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Sao Paulo, Brazil
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14
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Hammoudeh H, Carracho L, Beard C, Razzoog M. Effect of different surface and heat treatments on the surface roughness, crystallography, and phase composition of high translucency zirconia for monolithic restorations. J Prosthet Dent 2024; 131:164.e1-164.e11. [PMID: 37945513 DOI: 10.1016/j.prosdent.2023.09.038] [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: 01/29/2023] [Revised: 09/24/2023] [Accepted: 09/27/2023] [Indexed: 11/12/2023]
Abstract
STATEMENT OF PROBLEM High translucency zirconia (HTZ) has gained popularity as an esthetic computer-aided design and computer-aided manufacturing (CAD-CAM) material for monolithic restorations. A detailed comparison between different common surface and heat treatments with a non-treated HTZ control to explain the behavior of the material under stress is lacking. PURPOSE The purpose of this in vitro study was to evaluate the effect of different surface and heat treatments on the surface roughness parameters (SRPs), topography, crystallography, and phase composition of HTZ used for monolithic restorations. MATERIAL AND METHODS Ninety Ø11.9×1.18-mm HTZ disks (Prettau Anterior) were milled, sintered, and distributed into 9 groups (n=10); 8 experimental (coarse diamond grinding GC, fine diamond grinding GF, fine diamond grinding and 3-step polishing kit GF+P1, fine diamond grinding and 3-step polishing kit and diamond paste GF+P1+DP, fine diamond grinding and 2-step polishing kit GF+P2, fine diamond grinding and GF+Gl, fine diamond grinding and 3-step polishing and glazing GF+P1+Gl, airborne-particle abrasion with 50-µm alumina), and a control group (C, as-sintered). SRPs (AveSa, AveSv, AveSz) and 3-dimensional (3D) images were obtained using a noncontact 3D-optic-profilometer. The crystal structure was determined with scanning electron microscopy. Phase composition was analyzed by X-ray diffraction (XRD). Surface roughness parameters data were statistically analyzed by 1-way ANOVA and the Tukey HSD test (α=.05). RESULTS The applied surface and heat treatment resulted in significantly different SRP mean values (P<.001) with different topographies. GC had the highest AveSa, AveSv, and AveSz mean values (0.95, 8.8, 17.4 µm, respectively) with significant microcracks. GF had significantly lower SRP with finer microcracks. GF+P1 had a significantly smoother surface, but GF+P2 resulted in SRP comparable with the GF group. GF+P1+DP had the smoothest homogenous surface (mean Sa: 0.08 µm). GF+P1 and GF+GL were equally effective, while GF+P1+GL was not superior. Airborne-particle abrasion produced a low Sa mean value (0.11 µm) with relatively high Sv and Sz mean values (5.9, 9.2 µm, respectively) and microcracks. A monoclinic phase was detected in all groups. All experimental groups had broadened XRD-peaks with lower intensity, suggesting the presence of the rhombohedral phase. CONCLUSIONS The different surface and heat treatments altered the HTZ crystals and their surface roughness with distinct topographies. Cubic crystal changes take place under stress as shown by the scanning electron microscope and the XRD diffraction pattern and may transform to the rhombohedral phase.
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Affiliation(s)
- Hanin Hammoudeh
- Assistant Professor, Restorative and Prosthodontics Department, The Ohio State University College of Dentistry, Columbus, Ohio; and Scholar, University of Jordan School of Dentistry, Amman, Jordan.
| | - Luis Carracho
- Assistant Professor, Department of Fixed Prosthodontics, University of Lisbon, Portugal; and Private Practice, Lisbon, Portugal
| | - Charles Beard
- Assistant Professor and Senior Clinical Lecturer, Biologic and Materials Sciences and Prosthodontics Department, University of Michigan School of Dentistry, Ann Arbor, Mich
| | - Michael Razzoog
- Professor Emeritus, Biologic and Materials Sciences and Prosthodontics Department, University of Michigan School of Dentistry, Ann Arbor, Mich
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15
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Spitznagel F, Prott L, Hoppe J, Manitckaia T, Blatz M, Zhang Y, Langner R, Gierthmuehlen P. Minimally invasive CAD/CAM lithium disilicate partial-coverage restorations show superior in-vitro fatigue performance than single crowns. J ESTHET RESTOR DENT 2024; 36:94-106. [PMID: 38009505 PMCID: PMC10872741 DOI: 10.1111/jerd.13169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 10/31/2023] [Accepted: 11/01/2023] [Indexed: 11/29/2023]
Abstract
OBJECTIVE To analyze the influence of restoration design (partial-coverage restoration vs. crown) and ceramic layer thickness on the performance and failure loads of CAD/CAM-fabricated lithium disilicate (LDS) reconstructions on molars after fatigue. MATERIALS AND METHODS Seventy-two posterior monolithic CAD/CAM-fabricated LDS restorations (IPS e.max CAD, Ivoclar Vivadent) with different occlusal/buccal ceramic layer thicknesses (1.5/0.8, 1.0/0.6, and 0.5/0.4 mm) and restoration designs (PCR: non-retentive full-veneer/partial-coverage restoration, C: crown,) were investigated and divided into six groups (n = 12, test: PCR-1.5, PCR-1.0, PCR-0.5; control: C-1.5, C-1.0, C-0.5). LDS restorations were adhesively bonded (Variolink Esthetic DC, Ivoclar Vivadent) to dentin-analogue composite dies (Z100, 3M ESPE). All specimens were subjected to thermomechanical loading (1.2 million cycles, 49 N, 1.6 Hz, 5-55°C) and exposed to single load to failure testing. Failure analysis was performed with light and scanning electron microscopies. Data were statistically analyzed using ANOVA, Tukey-Test, and t-test (p < 0.05). RESULTS Eight crown samples (C-0.5) and one PCR specimen (PCR-0.5) revealed cracks after fatigue, resulting in an overall success rate of 87.5% (crowns: 75%, PCRs: 96.88%). Direct comparisons of PCRs versus crowns for thicknesses of 0.5 mm (p < 0.001) and 1.0 mm (p = 0.004) were significant and in favor of PCRs. Minimally invasive PCRs (0.5 and 1.0 mm) outperformed crowns with the identical ceramic thickness. No difference was detected (p = 0.276) between thickness 1.5 mm PCRs and crowns. CONCLUSIONS Minimally invasive monolithic CAD/CAM-fabricated posterior LDS PCRs (0.5 and 1.0 mm) resulted in superior failure load values compared to minimally invasive crowns. Minimally invasive crowns (0.5 mm) are prone to cracks after fatigue. CLINICAL SIGNIFICANCE Minimally invasive CAD/CAM-fabricated LDS PCR restorations with a non-retentive preparation design should be considered over single crowns for molar rehabilitation.
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Affiliation(s)
- F.A. Spitznagel
- Department of Prosthodontics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University, Düsseldorf, Germany
- Department of Preventive and Restorative Sciences, Penn Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - L.S. Prott
- Department of Prosthodontics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University, Düsseldorf, Germany
| | - J.S. Hoppe
- Department of Prosthodontics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University, Düsseldorf, Germany
| | - T. Manitckaia
- Department of Prosthodontics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University, Düsseldorf, Germany
| | - M.B. Blatz
- Department of Preventive and Restorative Sciences, Penn Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Y. Zhang
- Department of Preventive and Restorative Sciences, Penn Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - R. Langner
- Institute of Systems Neuroscience, Medical Faculty, Heinrich-Heine-University Düsseldorf, Germany
- Institute of Neuroscience and Medicine, Brain and Behavior (INM-7), Research Center Jülich, Germany
| | - P.C. Gierthmuehlen
- Department of Prosthodontics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University, Düsseldorf, Germany
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16
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Sulaiman TA, Suliman AA, Abdulmajeed AA, Zhang Y. Zirconia restoration types, properties, tooth preparation design, and bonding. A narrative review. J ESTHET RESTOR DENT 2024; 36:78-84. [PMID: 37840220 PMCID: PMC10842315 DOI: 10.1111/jerd.13151] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/01/2023] [Accepted: 10/03/2023] [Indexed: 10/17/2023]
Abstract
OBJECTIVE The purpose of this review was to provide dental professionals with information regarding the various types of zirconia restorations, their mechanical and optical properties, tooth preparation design, and bonding protocol in an effort to enhance the longevity and durability of zirconia restorations. OVERVIEW The yttria content of zirconia ceramics determines their classification. The mechanical and optical properties of each type are discussed, with an emphasis on the effect of yttria concentration on the properties of zirconia. The processing and sintering methods are also discussed as they have a direct impact on the properties of zirconia. The design of tooth preparation, specifically occlusal reduction, varies depending on the type of zirconia used in each case. Finally, a protocol for zirconia restoration bonding is described to ensure optimal bonding to the tooth structure. CONCLUSION Not all zirconia restorations are the same. The selection of zirconia type based on yttria concentration, processing and sintering methods, tooth preparation design, and adherence to the bonding protocol are all critical to the success and longevity of zirconia restorations. CLINICAL SIGNIFICANCE Zirconia restorations are the most commonly used indirect restorative material. The selection of the most appropriate zirconia type based on its yttria content, which determines its strength and translucency, is critical to the success and the longevity of the restoration. Tooth preparation design also influences the strength and translucency of the zirconia. Air-borne particle abrasion, followed by a ceramic primer and resin cement, can ensure a durable bond to the tooth structure.
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Affiliation(s)
- Taiseer A Sulaiman
- Division of Comprehensive Oral Health, University of North Carolina, Adams School of Dentistry, Chapel Hill, North Carolina, USA
| | - Abdulhaq A Suliman
- Department of Clinical Sciences, College of Dentistry, Ajman University, Ajman, UAE
| | - Aous A Abdulmajeed
- Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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17
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Lopes MWP, Borba M, Bortoluzzi A, Zanatta M, Bervian J, Collares KF. Fatigue and marginal adaptation of bulk fill restoratives: Effect of the layering technique and cavity dimension of extensively damaged teeth. Dent Mater 2023; 39:1032-1039. [PMID: 37775461 DOI: 10.1016/j.dental.2023.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 09/20/2023] [Accepted: 09/22/2023] [Indexed: 10/01/2023]
Abstract
OBJECTIVES To evaluate the effect of layering technique and cavity dimension on the fatigue behavior and marginal adaptation of bulk fill (BF) restorations in extensively damaged teeth. METHODS Seventy-two premolars received class II cavities (MOD) followed by endodontic treatment. Half sample had 1/3 of their palatal cusp removed. Teeth were restored using three techniques: (I) incremental, with conventional resin composite (RC); (C) combined, using BF flow and RC, (B) bulk fill, with regular BF. Specimens were subjected to fatigue (80 N, 2 Hz, 37° C water) for 1 million cycles (n = 12). The test was interrupted every 250,000 cycles to evaluate tooth integrity, restoration fracture and adaptation using FDI criteria. Images of the proximal surfaces were obtained before and after the cycling to measure the gap. Restoration fatigue survival and success were analyzed using Weibull distribution and Maximum Likelihood Estimation. Gap thickness was analyzed with Kruskal-Wallis and Student-Newman-Keuls tests (α = 0.05). RESULTS For the survival analysis, Weibull modulus (β) and characteristic lifetime (η) were similar among groups. Yet, for the success analysis, in which only restorations that were free of technical complications were ranked as success, the bulk-fill technique resulted in higher β, while the combined technique produced restorations with higher η, for teeth that had their cusp removed. C-technique also resulted in smaller gaps than I and B. SIGNIFICANCE The effect of the layering technique on the success of restorations was dependent on the cavity extension. The combined technique favors the adaptation and the longevity of extensively damaged teeth.
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Affiliation(s)
| | - Márcia Borba
- Graduate Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil; Dental Division, School of Medical Sciences, University of Manchester, Manchester, UK.
| | | | - Matheus Zanatta
- Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil
| | - Juliane Bervian
- Graduate Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil
| | - Kaue Farias Collares
- Graduate Program in Dentistry, Dental School, Federal University of Pelotas, Pelotas, RS, Brazil
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18
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Antón X, Liebermann A, Hampe R, Joda T, Stawarczyk B. Impact of high-speed sintering and choice of preshaded monochrome or multilayered blanks on fatigue behavior of 4 mol% yttria-stabilized tetragonal zirconia polycrystal. J Prosthet Dent 2023; 130:639-645. [PMID: 34930599 DOI: 10.1016/j.prosdent.2021.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 10/31/2021] [Accepted: 11/01/2021] [Indexed: 11/25/2022]
Abstract
STATEMENT OF PROBLEM High-speed sintering allows the rapid fabrication of esthetic restorations with adequate flexural strength. However, data on the fatigue behavior of high-speed sintered 4 mol% yttria-stabilized tetragonal zirconia polycrystal (4Y-TZP) are lacking. PURPOSE The purpose of this in vitro study was to examine the effect of high-speed sintering and the preshading of blanks (monochrome versus multilayer) on the fatigue behavior of 4Y-TZP ceramics. MATERIAL AND METHODS Four-point flexural strength specimens (N=405) were fabricated from high-speed sintered multilayer 4Y-TZP (Zolid DRS) processed at 1580 °C for about 20 minutes and conventionally sintered at 1450 °C for about 10 hours, multilayer 4Y-TZP (Zolid Gen-x), and monochrome 4Y-TZP (Ceramill Zolid HT+PS), the control group. The specimens were loaded under 5 different dynamic test conditions for fatigue testing (P1-P5). Three were step-stress protocols (P1: 50 N for 5000 cycles; P2: 10 N for 1000 cycles, P3: 5% for 5000 cycles), 1 was tested with a constant force of 720 N (P4), and 1 was tested for different constant load levels (P5). For analysis of P1-P3, the Kaplan-Meier test and Mantel Cox test were performed (α=.05). P4 was analyzed with the Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests, and P5 by creating a load-cycle diagram. A fracture analysis was performed. RESULTS ZMLC showed better fatigue behavior than ZMLH (P≤.006) and ZMOC (P≤.002) in all 3 step-stress protocols (P1-P3). ZMLH showed results comparable with those for ZMOC (P≥.285). In P4 and P5, all materials showed comparable values (P=.163 for P4). CONCLUSIONS The multilayer technique showed a positive effect on the fatigue behavior of 4Y-TZP. In contrast, high-speed sintering negatively influenced the fatigue behavior of multilayer 4Y-TZP. The high-speed sintered material showed no deterioration compared with the conventional sintered monochrome material.
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Affiliation(s)
- Xenia Antón
- Doctoral student, Dental Materials Unit, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany.
| | - Anja Liebermann
- Assistant Professor, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany
| | - Rüdiger Hampe
- Guest Researcher, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany
| | - Tim Joda
- Professor, Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, Basel, Switzerland
| | - Bogna Stawarczyk
- Scientific Head, Dental Materials Unit, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany
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Barreto LAL, Grangeiro MTV, Prado PHCO, Bottino MA, Dal Piva AMDO, Ramos NDC, Tribst JPM, Junior LN. Effect of Finishing Protocols on the Surface Roughness and Fatigue Strength of a High-Translucent Zirconia. Int J Dent 2023; 2023:8882878. [PMID: 37780934 PMCID: PMC10541300 DOI: 10.1155/2023/8882878] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 08/16/2023] [Accepted: 08/29/2023] [Indexed: 10/03/2023] Open
Abstract
Purpose In case of need for esthetical improvement of zirconia restorations, an individualization using extrinsic staining can be applied. This study aimed to evaluate the surface roughness and fatigue strength (survival) of high-translucency zirconia (3Y-TZP, YZ®HT, Vita Zanhfabrik) with extrinsic characterization and/or glaze. Methods Sixty (60) zirconia discs (12 × 1.2 mm) were obtained, sintered, and randomly distributed among three groups (n = 20) according to the surface finishing protocol: C (control), C + G (extrinsic characterization followed by a glaze layer), and G (glaze layer). The surface roughness (Ra) was analyzed with a contact profilometer. Subsequently, the specimens were subjected to a fatigue load profile starting at 120 N during 20,000 cycles at 4 Hz frequency, with a 5% increase at each step until failure. The failed specimens were evaluated under a stereomicroscope. Surface roughness analysis was evaluated by using one-way ANOVA and post hoc Tukey tests (95%); while fatigue survival probability was analyzed with Kaplan-Meier and Mantel-Cox (log- rank, 95%). Results One-way ANOVA revealed that surface roughness was affected by the finishing protocol, where C + G showed the highest mean value (0.46 ± 0.18 µm)A followed by G (0.30 ± 0.10 µm)B, and C (0.19 ± 0.02 µm)C. While for fatigue strength, the G protocol presented a higher mean value (243.00, and 222.36-263.63)A, followed by C + G (192.75 and 186.61-198.88)B and C (172.50 and 159.43-185.56)C. Conclusion Surface finishing protocols modify the surface roughness and fatigue strength of high-translucent zirconia. Regardless of the surface roughness, both glazing protocols improved the ceramic fatigue strength, favoring the restoration's long-term survival.
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Affiliation(s)
- Larissa Araújo Lopes Barreto
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (Unesp), Eng. Francisco José Longo Avenue, 777, São José dos Campos, SP, Brazil
| | - Manassés Tercio Vieira Grangeiro
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (Unesp), Eng. Francisco José Longo Avenue, 777, São José dos Campos, SP, Brazil
| | - Pedro Henrique Condé Oliveira Prado
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (Unesp), Eng. Francisco José Longo Avenue, 777, São José dos Campos, SP, Brazil
| | - Marco Antonio Bottino
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (Unesp), Eng. Francisco José Longo Avenue, 777, São José dos Campos, SP, Brazil
| | - Amanda Maria de Oliveira Dal Piva
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, Netherlands
| | - Nathalia de Carvalho Ramos
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (Unesp), Eng. Francisco José Longo Avenue, 777, São José dos Campos, SP, Brazil
| | - João Paulo Mendes Tribst
- Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, Netherlands
| | - Lafayette Nogueira Junior
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (Unesp), Eng. Francisco José Longo Avenue, 777, São José dos Campos, SP, Brazil
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Humm VL, Sailer I, Thoma DS, Hämmerle CHF, Jung RE, Zembic A. 13-year follow-up of a randomized controlled study on zirconia and titanium abutments. Clin Oral Implants Res 2023; 34:911-919. [PMID: 37340530 DOI: 10.1111/clr.14117] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 05/22/2023] [Accepted: 06/04/2023] [Indexed: 06/22/2023]
Abstract
OBJECTIVES To assess survival rates and compare technical, biological, and esthetic outcomes of customized zirconia and titanium abutments at 13 years post loading. MATERIALS AND METHODS Initially, 22 patients with 40 implants in posterior regions were included. The sites were randomly assigned to 20 customized zirconia abutments with cemented all ceramic crowns (ACC) and 20 customized titanium abutments with cemented metal ceramic crowns (MCC). At a mean follow-up of 13.4 years, patients were examined and implants/restorations assessed for survival and technical complications, as well as biological and esthetic outcomes (pocket probing depth [PPD], bleeding on probing [BOP], plaque control record [PCR], bone level [BL], papilla index [PAP], mucosal thickness, and recession (distance of the margo mucosae [MM]/margo gingivae MG)). Descriptive analyses were performed for all outcome measures. RESULTS Fifteen patients with 21 abutments (13 zirconia, 8 titanium) were examined at 13 years. The drop-out rate was 25% (patient level). The technical survival rate of the abutments was 100%. The survival rate on the restorative level (crowns) was 100%. The assessed biological outcomes (PPD, PCR, BOP, BL) and esthetic outcomes (MG, PAP) were similar. CONCLUSIONS Zirconia and titanium abutments supporting single implant-borne restorations rendered a high survival rate and minimal differences in terms of technical, biological, and esthetic outcomes at 13 years of follow-up.
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Affiliation(s)
- Viviane Laura Humm
- Clinic of Reconstructive Dentistry, Center of Dental Medicine, University of Zürich, Zürich, Switzerland
- Private practice, Winterthur, Switzerland
| | - Irena Sailer
- Division of Fixed Prosthodontics and Occlusion, University clinics for Dental Medicine, University of Geneva, Geneva, Switzerland
| | - Daniel Stefan Thoma
- Clinic of Reconstructive Dentistry, Center of Dental Medicine, University of Zürich, Zürich, Switzerland
| | | | - Ronald Ernst Jung
- Clinic of Reconstructive Dentistry, Center of Dental Medicine, University of Zürich, Zürich, Switzerland
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Alves WG, Souza LFB, Pereira GKR, Valandro LF, Kapczinski MP, Mengatto CM, Fraga S. Fit and fatigue behavior of CAD-CAM lithium disilicate crowns. J Prosthet Dent 2023; 130:241.e1-241.e8. [PMID: 37328406 DOI: 10.1016/j.prosdent.2023.05.007] [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: 01/30/2023] [Revised: 05/19/2023] [Accepted: 05/19/2023] [Indexed: 06/18/2023]
Abstract
STATEMENT OF PROBLEM New computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate glass-ceramics have been marketed. However, information concerning their biomechanical behavior is lacking. PURPOSE The purpose of this in vitro study was to compare the fit and fatigue behavior of two recently introduced CAD-CAM lithium disilicate materials with the standard IPS e.max CAD ceramic and to investigate the effect of the thermal treatment for crystallization on crown fit. MATERIAL AND METHODS Monolithic crowns (n=15) were milled from 3 CAD-CAM lithium disilicates: IPS e.max CAD (Ivoclar AG), Rosetta SM (Hass), and T-lithium (Shenzhen Upcera Dental Technology). Marginal and internal fit were evaluated using the replica technique before and after crystallization, and the fatigue behavior of the luted crowns was evaluated by the step-stress method. One-way ANOVA and the Tukey test were used to compare fit among the materials. Fatigue failure load was evaluated by the Kaplan-Meier and Mantel-Cox tests. The effect of crystallization on fit was evaluated with the paired t test (α=.05). RESULTS Marginal fit was different between IPS e.max CAD (74 μm) and Rosetta SM (63 μm) (P=.02). T-lithium was similar to the other ceramics (68 μm) (P>.05). Occlusal internal space was similar among all materials (P=.69). Fatigue failure loads of Rosetta SM (1160 N) and T-lithium (1063 N) were similar to IPS e.max CAD (1082 N) (P>.05). The fatigue failure load of Rosetta SM was higher than that of T-lithium (P=.04). Crystallization reduced the axial internal space of all materials (P<.05) without significantly affecting marginal fit (P>.05). CONCLUSIONS The fit and fatigue behavior of Rosetta SM and T-lithium were similar to that of IPS e.max CAD. Crystallization reduced the internal space of the crowns.
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Affiliation(s)
- William Garcia Alves
- Graduate student, Department of Conservative Dentistry, School of Dentistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil
| | - Luiza Freitas Brum Souza
- Postgraduate Student, Post-Graduate Program in Dental Science, Prosthodontics Unit, Department of Restorative Dentistry, Universidade Federal de Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | - Gabriel Kalil Rocha Pereira
- Adjunct Professor, Department of Restorative Dentistry, Universidade Federal de Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | - Luiz Felipe Valandro
- Professor, Department of Restorative Dentistry, Universidade Federal de Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | - Myriam Pereira Kapczinski
- Associate Professor, Department of Conservative Dentistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil
| | - Cristiane Machado Mengatto
- Associate Professor, Department of Conservative Dentistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil
| | - Sara Fraga
- Adjunct Professor, Department of Conservative Dentistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.
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Capobianco V, Baroudi K, Santos MJMC, Rubo JH, Rizkalla AS, Dal Piva AMDO, Vitti RP, Tribst JPM, Santos GC. Post-fatigue fracture load, stress concentration and mechanical properties of feldspathic, leucite- and lithium disilicate-reinforced glass ceramics. Heliyon 2023; 9:e17787. [PMID: 37449193 PMCID: PMC10336509 DOI: 10.1016/j.heliyon.2023.e17787] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/09/2023] [Accepted: 06/28/2023] [Indexed: 07/18/2023] Open
Abstract
Objective To evaluate the mechanical properties of different CAD/CAM ceramic systems and the post-fatigue fracture and stress distribution when used as cemented crowns. Materials and methods Sixty (60) CAD/CAM monolithic crowns were milled using three different ceramic materials (FD - Feldspathic [Vita Mark II]), LE - Leucite-based ceramic [IPS Empress CAD] and LD - Lithium Disilicate [IPS e.max CAD]) and adhesively cemented on resin composite dyes. Specimens were stored in distillated water (37 °C) for 7 days. After, half of the crowns were submitted to immediate fracture load test while the other half was submitted to fatigue cycling. The average cement layer of approximately 80 μm was assessed using scanning electron microscopy (SEM). The average thickness was used in the three-dimensional (3D) Finite Element Analysis (FEA). For each ceramic material, the density, Poisson ratio, shear modulus, Young modulus, fracture toughness, and true hardness were assessed (n = 3). The data was used to assess the Maximum Principal Stress throughout 3D-FEA according to each material during load to fail and post-fatigue. Data were submitted to two-way ANOVA and Tukey test (α = 0.05). Results LD showed the highest compression load, density, shear modulus, Young modulus, fracture toughness and true hardness values. While LE presented the lowest mechanical properties values. There is no difference in the Poisson ratio between the evaluated ceramics. Conclusion LD was susceptible to aging process but presented stronger physicomechanical properties, showing the highest post-fatigue fracture load and highest stress magnitude.
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Affiliation(s)
| | - Kusai Baroudi
- RAK College of Dental Sciences, RAK Medical & Health Sciences University, RAS Al Khaimah, United Arab Emirates
- School of Dentistry, University of Taubaté, Taubaté, SP, Brazil
| | | | | | - Amin S. Rizkalla
- Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada
| | - Amanda Maria de Oliveira Dal Piva
- Department of Dental Materials, Academic Centre for Dentistry Amsterdam (ACTA),Universiteit van Amsterdam en Vrije Universiteit, Amsterdam, the Netherlands
| | - Rafael Pino Vitti
- School of Dentistry, Herminio Ometto University Center, Araras, SP, Brazil
| | - João Paulo Mendes Tribst
- Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA),Universiteit van Amsterdam en Vrije Universiteit, Amsterdam, the Netherlands
| | - Gildo Coelho Santos
- Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON, Canada
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Yoon Y, Lee MJ, Kang I, Oh S. Evaluation of Biomechanical Stability of Teeth Tissue According to Crown Materials: A Three-Dimensional Finite Element Analysis. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4756. [PMID: 37445067 DOI: 10.3390/ma16134756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 06/18/2023] [Accepted: 06/27/2023] [Indexed: 07/15/2023]
Abstract
The biomechanical effects of dental tissue according to various dental crown materials were investigated using finite element analysis. Bone, prepared tooth, root canal, and periodontal ligament were modeled based on computed tomography. Depending on the characteristics of the crown material, it was classified into zirconia, hybrid ceramic, gold alloy, and acrylic resin. A loading force of 200 N was applied in the vertical direction to the occlusal surface of the crown, and analysis was performed under the condition that all interfaces were tied. The results demonstrate that the highest von Mises stress was shown in the prepared tooth of the acrylic resin model, which is a temporary prosthesis, and the pulpal pressure was also the highest. Additionally, among the final prosthesis, the highest stress was shown in the hybrid ceramic model prepared teeth. The properties of restoration materials can be a factor influencing the tooth structure. Thus, in order to make a correct decision when selecting a material for restorative treatment, it is necessary to understand, analyze, and evaluate the properties of these restoration materials.
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Affiliation(s)
- Youngjae Yoon
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Myung-Jin Lee
- Department of Dental Hygiene, Division of Health Science, Baekseok University, Cheonan 31065, Republic of Korea
| | - Inyeong Kang
- School of Mechanical Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Sanghwan Oh
- Department of Dental Hygiene, Konyang University, Daejeon 35365, Republic of Korea
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Fouda AM, Atta O, Özcan M, Stawarczyk B, Glaum R, Bourauel C. An investigation on fatigue, fracture resistance, and color properties of aesthetic CAD/CAM monolithic ceramics. Clin Oral Investig 2023; 27:2653-2665. [PMID: 36574045 PMCID: PMC10264477 DOI: 10.1007/s00784-022-04833-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 12/18/2022] [Indexed: 12/28/2022]
Abstract
OBJECTIVES To evaluate and compare fracture resistance, translucency, and color reproducibility, as well as the effect of aging on the fracture load and color stability of novel monolithic CAD/CAM ceramics. MATERIALS AND METHODS One hundred crowns of uniform thickness were milled from five ceramic blocks (n = 20): partially crystallized lithium disilicate (PLD) and fully crystallized lithium disilicate (FLD), lithium metasilicate (LMS), 4Y-TZP (SMZ), and 5Y-TZP (UMZ) monolithic zirconia. PLD crowns were glazed, LMS was fired, and FLD was polished. SMZ and UMZ crowns were sintered and polished. Crowns were adhesively cemented to epoxy dies. Half of the crowns (n = 10) were subjected to 1.200.000 load cycles with thermal cycling. Color space values L, a, b defined by the Commission Internationale de l´Eclairage (CIELAB) were measured before and after aging, and (∆E) was calculated. Both aged and non-aged specimens were loaded until fracture in a universal testing machine and the fracture load was recorded. X-ray diffraction (XRD) and scanning electron microscope (SEM) fractographic analysis were carried out on fractured fragments of representative samples. For translucency and color reproducibility, 50 rectangular-shaped specimens were fabricated and processed as described previously. Color values were measured over black and white backgrounds, and the translucency parameter (TP) was computed. Using the shade verification mode, (∆E) to shade A3 was calculated. Data were statistically analyzed using one-way and two-way ANOVA, and t-test. RESULTS Aging did not affect fracture resistance significantly (p > 0.05). The highest mean fracture load was obtained for the SMZ and UMZ. A significant color change was observed after aging in all groups. The highest TP was noted for FLD. SMZ and UMZ had the best shade match. CONCLUSIONS Zirconia showed higher fracture resistance and color stability than lithium silicate ceramics. Lithium silicate ceramics were more translucent. The experimental FLD demonstrated high translucency. CLINICAL RELEVANCE Tested ceramics showed sufficient stability to withstand masticatory forces. Characterization of final restorations might be mandatory for better color match.
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Affiliation(s)
- Ahmed Mahmoud Fouda
- Department of Oral Technology, University Hospital Bonn, Bonn University, Welschnonnenstr. 17, 53111, Bonn, Germany.
- Department of Fixed Prosthodontics, Suez Canal University, Ismailia, Egypt.
| | - Osama Atta
- Department of Fixed Prosthodontics, Suez Canal University, Ismailia, Egypt
| | - Mutlu Özcan
- Division of Dental Biomaterials, Center for Dental Medicine, Clinic for Reconstructive Dentistry, University of Zurich, Zurich, Switzerland
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany
| | - Robert Glaum
- Institute of Inorganic Chemistry, Bonn University, Bonn, Germany
| | - Christoph Bourauel
- Department of Oral Technology, University Hospital Bonn, Bonn University, Welschnonnenstr. 17, 53111, Bonn, Germany
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Weber KR, Meneghetti DE, Benetti P, Della Bona A, Griggs JA, Borba M. Influence of piston material on the fatigue behavior of a glass-ceramic. J Prosthet Dent 2023; 129:931-937. [PMID: 34482967 PMCID: PMC8888770 DOI: 10.1016/j.prosdent.2021.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 08/02/2021] [Accepted: 08/02/2021] [Indexed: 11/15/2022]
Abstract
STATEMENT OF PROBLEM The lack of standardization regarding the loading piston material used in fatigue tests could limit the interpretation of study findings. PURPOSE The purpose of this in vitro study was to evaluate the effect of the piston material on the fatigue behavior of a lithium disilicate glass-ceramic. MATERIAL AND METHODS Plate-shaped, 1.2-mm-thick, lithium disilicate glass-ceramic specimens were cemented onto a dentin analog substrate with resin cement. The specimens were divided into 4 groups according to the piston material used in the fatigue test (n=30): metal, glass fiber-reinforced epoxy resin, ceramic, and human tooth. The fatigue test was performed in a mechanical cycling machine by using the boundary technique at 2 Hz in distilled water at 37 °C. The fatigue data were analyzed by using the Weibull distribution and a lifetime-inverse power law relationship. Failures were evaluated with fractography and transillumination. RESULTS The Weibull modulus (β) was similar among groups. The exponent of crack growth (n) was significantly greater for glass fiber-reinforced epoxy resin and tooth groups than for metal and ceramic; therefore, the probability of failure (Pf) of glass-ceramic specimens loaded by resin and tooth pistons depended more on load amplitude. Specimens tested with tooth showed the highest value of K (characteristic lifetime), which is an indication of greater survival. Radial crack was the only failure mode observed for all experimental groups. CONCLUSIONS The piston material influenced the fatigue survival of the lithium disilicate glass-ceramic. The glass fiber-reinforced epoxy resin piston closely simulated the fatigue behavior induced by the human tooth on the evaluated glass-ceramic.
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Affiliation(s)
- Katia R Weber
- PhD student, Post-Graduation Program in Dentistry, Dental School, University of Passo Fundo (UPF), Passo Fundo, RS, Brazil
| | - Daniel E Meneghetti
- Predoctoral student, Dental School, University of Passo Fundo (UPF), Passo Fundo, RS, Brazil
| | - Paula Benetti
- Professor, Post-Graduation Program in Dentistry, Dental School, University of Passo Fundo (UPF), Passo Fundo, RS, Brazil
| | - Alvaro Della Bona
- Professor, Post-Graduation Program in Dentistry, Dental School, University of Passo Fundo (UPF), Passo Fundo, RS, Brazil
| | - Jason A Griggs
- Professor, Department of Biomedical Materials Science, University of Mississippi Medical Center, Jackson, Miss
| | - Márcia Borba
- Professor, Post-Graduation Program in Dentistry, University of Passo Fundo, Passo Fundo, RS, Brazil.
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Velho HC, da Rosa LS, Dapieve KS, Borges ALS, Pereira GKR, Venturini AB, Valandro LF. How does the occlusal contact region influence the mechanical fatigue performance and fracture region of monolithic lithium disilicate ceramic crowns? J Mech Behav Biomed Mater 2023; 140:105746. [PMID: 36878081 DOI: 10.1016/j.jmbbm.2023.105746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/23/2023] [Accepted: 02/26/2023] [Indexed: 03/05/2023]
Abstract
OBJECTIVE To characterize the effect of the occlusal contact region on the mechanical fatigue performance and on the fracture region of monolithic lithium disilicate ceramic crowns. MATERIALS AND METHODS Monolithic lithium disilicate ceramic crowns were machined in a CAD/CAM system and adhesively luted onto glass-fiber reinforced epoxy resin preparations with resin cement. The crowns were divided into three groups (n = 16) according to load application region (cusp tip: restricted to cusp tips; cusp plane: restricted to cuspal inclined plane; or mixed: associating tip cusp and cuspal inclined plane). The specimens were submitted to a cyclic fatigue test (initial load: 200 N; step-size: 100 N; cycles/step: 20,000; loading frequency: 20 Hz; load applicator: 6 mm or 40 mm diameter stainless steel) until observing cracks (1st outcome) and fracture (2nd outcome). The data were analyzed by the Kaplan-Meier + Mantel-Cox post-hoc tests for both outcomes (cracks and fracture). Finite element analysis (FEA), occlusal contact region, contact radii measurements, and fractographic analyzes were performed. RESULTS The mixed group presented worse fatigue mechanical behavior (550 N / 85.000 cycles) compared to the cuspal inclined plane group (656 N / 111,250 cycles) (p < 0.05) for the first crack outcome, while the cusp tip group was similar to both groups (588 N / 97,500 cycles) (p > 0.05). The mixed group had the worst fatigue behavior (1413 N / 253,029 cycles) in relation to the other groups (Cusp tip: 1644 N / 293,312 cycles; Cuspal inclined plane: 1631 N / 295,174 cycles) considering the crown fracture outcome (p < 0.05). FEA showed higher tensile stress concentration areas just below the load application region. In addition, loading on the cuspal inclined plane induced a higher tensile stress concentration in the groove region. The most prevalent type of crown fracture was the wall fracture. Groove fracture was observed in 50% of the loading specimens exclusively on the cuspal inclined plane. CONCLUSION Load application on distinct occlusal contact regions affects the stress distribution pattern and consequently the mechanical fatigue performance and fracture region of the monolithic lithium disilicate ceramic crowns. A combination of loading at distinct regions is recommended to promote better evaluation of the fatigue behavior of a restored set.
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Affiliation(s)
- Helder Callegaro Velho
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Lucas Saldanha da Rosa
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Kiara Serafini Dapieve
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Alexandre Luiz Souto Borges
- Department of Dental Materials and Prosthodontics, São Paulo State University, São José dos Campos, São Paulo, Brazil.
| | - Gabriel Kalil Rocha Pereira
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Andressa Borin Venturini
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, 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 Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
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Mert Eren M, Celebi AT, İçer E, Baykasoğlu C, Mugan A, Yücel T, Yıldız E. Biomechanical Behavior Evaluation of Resin Cement with Different Elastic Modulus on Porcelain Laminate Veneer Restorations Using Micro-CT-Based Finite Element Analysis. MATERIALS (BASEL, SWITZERLAND) 2023; 16:2378. [PMID: 36984260 PMCID: PMC10054651 DOI: 10.3390/ma16062378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/02/2023] [Accepted: 03/10/2023] [Indexed: 06/18/2023]
Abstract
The aim of this study is to evaluate the biomechanical behavior of the porcelain laminate veneer restorations (PLV) of the maxillary central incisor luted with two types of resin cements having different incisal preparations: butt joint and palatal chamfer. Biomechanical analyses were performed using the micro-CT-based finite element models, and von Mises stress and strain values of the PLV, resin cement, adhesive layer, and tooth structure were computed. The PLV with butt joint preparation showed larger stress values than those of restored with palatal chamfer preparation, regardless of the elasticity of the cement and loading conditions. An increase in the elasticity modulus of the resin cement induced slightly larger stresses on the adhesive layer, tooth tissues, and restorative materials. Overall, this study demonstrates the role of the preparation design and luting materials on the mechanical behavior of the PLV restorations and discusses the potential failure mechanisms of the PLV restorations under different loading mechanisms.
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Affiliation(s)
- Meltem Mert Eren
- Department of Restorative Dentistry, Faculty of Dentistry, Altınbas University, 34147 Istanbul, Türkiye
| | - Alper Tunga Celebi
- Institute of Applied Physics, Vienna University of Technology, 1040 Vienna, Austria
| | - Esra İçer
- Department of Informatics, Technische Universität München, 85748 Garching, Germany
| | - Cengiz Baykasoğlu
- Faculty of Engineering Mechanical Engineering Department, Hitit University, 19030 Çorum, Türkiye
| | - Ata Mugan
- Mechanical Engineering Department, Faculty of Mechanical Engineering, Istanbul Technical University, 34437 Istanbul, Türkiye
| | - Taner Yücel
- Department of Restorative Dentistry, Faculty of Dentistry, Istanbul University, 34116 Istanbul, Türkiye
| | - Esra Yıldız
- Department of Restorative Dentistry, Faculty of Dentistry, Istanbul University, 34116 Istanbul, Türkiye
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Pilecco RO, Zucuni CP, Carvalho ABGD, Saavedra GDSFA, Marinho RMDM, Rocha Pereira GK, Valandro LF. Polishing the bonding surface, before or after crystallization, does not alter the fatigue behavior of bonded CAD-CAM lithium disilicate. J Mech Behav Biomed Mater 2023; 142:105794. [PMID: 37037152 DOI: 10.1016/j.jmbbm.2023.105794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/17/2023] [Accepted: 03/19/2023] [Indexed: 04/08/2023]
Abstract
The aim of this study was to assess if the finishing/polishing of the bonding surface of lithium disilicate ceramic, prior to or after crystallization, would affect the fatigue behavior of a bonded restorations. For this, lithium disilicate ceramic (IPS e.max CAD) discs (n = 15) were milled and randomly divided into 3 groups: CAD-CAM group which remained untouched; PRE group which received a finishing/polishing protocol (OptraFine system) prior to its crystallization; and POST group, which received the treatment after its crystallization. After surface treatments, ceramic and glass-fiber reinforced epoxy resin discs were paired and bonded using a resin cement (Multilink N). A cyclical fatigue test was conducted (frequency 20 Hz, initial load 200 N for 5000 cycles, step-size of 100 N for 10,000 cycles/step) until failure occurrence. Surface roughness and topography were analyzed. An initial descriptive analysis of surface roughness, FFL and CFF was performed to obtain the mean, standard deviation and confidence interval values (SPSS v. 21, SPSS Inc.) for statistical analysis. Roughness data was using one-way ANOVA with Tukey's post hoc test (α = 0.05), while the fatigue data was submitted to survival analysis with Kaplan-Meier test (α = 0.05) and Weibull modulus (Weibull++, Reliasoft). Neither the finishing/polishing procedure of the bonding surface, nor the moment (prior to or after crystallization), affected the fatigue behavior of bonded milled lithium disilicate. There were also no differences for mechanical reliability among conditions. Despite this, finishing/polishing reduced surface roughness and led to smoother topography. Finishing/polishing the bonding surface of milled lithium disilicate, before or after crystallization, does not alter the fatigue behavior of the bonded restorative set, although there is some influence on roughness and topography.
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Abstract
The purpose of this article is to review current understanding of lithia-based glass-ceramics and to identify future research needs for this class of dental materials in relation to novel compositions and fabrication methods. With rapid advances in material development and digital technology, time efficiency of dental workflow and fit accuracy of ceramic restorations are ever improving. Lithia-based glass-ceramics are at the forefront of this advance-new variants with more efficient fabrication routes are continually being introduced into the marketplace. Base glass composition, crystallization heat treatment, nucleant and coloration additives, and property gradation are some pertinent variables. The trend in fabrication is to move from CAD/CAM grinding of partially crystallized glass-ceramics to fully crystallized materials, thereby circumventing the need for postmachining firing altogether. In these endeavors, a better understanding of mechanical properties and evolving shaping technologies, such as ductile grinding, is paramount. Additive manufacturing and 3-dimensional printing methodologies offer a promising alternative to current CAD/CAM subtractive manufacturing routes. Challenges to the implementation of new technologies in efficient development and production of high-quality dental glass-ceramic prostheses are addressed.
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Affiliation(s)
- Y. Zhang
- Department of Preventive and
Restorative Sciences, School of Dental Medicine, University of Pennsylvania,
Philadelphia, PA, USA
| | - S. Vardhaman
- Department of Preventive and
Restorative Sciences, School of Dental Medicine, University of Pennsylvania,
Philadelphia, PA, USA
| | - C.S. Rodrigues
- Department of Dental Materials and
Prosthodontics, Institute of Science and Technology, São Paulo State University, São
José dos Campos, Brazil
| | - B.R. Lawn
- Material Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, MD, USA
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Demachkia AM, Velho HC, Valandro LF, Dimashkieh MR, Samran A, Tribst JPM, de Melo RM. Endocrown restorations in premolars: influence of remaining axial walls of tooth structure and restorative materials on fatigue resistance. Clin Oral Investig 2023:10.1007/s00784-023-04895-6. [PMID: 36781479 DOI: 10.1007/s00784-023-04895-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 02/01/2023] [Indexed: 02/15/2023]
Abstract
OBJECTIVES To evaluate the effect of the remaining tooth structure and different CAD/CAM materials on the fatigue performance and failure mode of endodontically treated premolars restored with endocrowns. MATERIALS AND METHODS Ninety maxillary premolars were endodontically treated and assigned into 6 groups (n = 15) according to the number of remaining axial walls (four, three, and two) and restorative materials (ultra-translucent zirconia 5Y-PSZ [KATANA UTML] and lithium disilicate [IPS e.max-CAD]). The specimens were subjected to cyclic fatigue loading test (initial load 200 N; 20 Hz). An incremental step load of 100 N per 10,000 cycles was applied until failure. The fatigue failure load (FFL) and number of failure cycles (CFFs) data were statistically analyzed with two-way ANOVA and Kaplan-Meier test (α = 0.05). Failed specimens were examined under a stereomicroscope 25 × and failure modes were determined. RESULTS FFL and CFF were significantly influenced by restorative material (p < 0.05). 5Y-PSZ endocrowns showed significantly higher FFL when compared with lithium disilicate. The number of remaining walls did not affect the fatigue behavior or failure mode of the specimens. Of the lithium disilicate restorations, 51% had repairable failures, while 95% 5Y-PSZ restorations had non-repairable failures. CONCLUSIONS Zirconia endocrowns showed better FFL than lithium disilicate endocrowns, regardless of the number of remaining axis walls. Lithium disilicate and 5Y-PSZ endocrowns showed FFL higher than the normal masticatory loads. CLINICAL RELEVANCE Restoring endodontically treated premolars with endocrown could be a promising treatment, regardless of the remaining axial walls. However, precaution should be taken in material selection since it affects the fatigue resistance and failure mode.
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Affiliation(s)
- Amir Mohidin Demachkia
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (UNESP), Av. Engenheiro Francisco José Longo,777. 12245000, São José Dos Campos, São Paulo, Brazil.
| | - Helder Callegaro Velho
- Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande Do Sul State, Brazil
| | - Luiz Felipe Valandro
- Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande Do Sul State, Brazil
| | - Mohiddin Rida Dimashkieh
- Department of Restorative and Prosthetic Dental Sciences, College of Dentistry, Dar Al-Uloom University, Riyadh, Saudi Arabia
| | - Abdulaziz Samran
- Department of Restorative and Prosthetic Dental Sciences, College of Dentistry, Dar Al-Uloom University, Riyadh, Saudi Arabia
| | - João Paulo Mendes Tribst
- Department of Oral Regenerative Medicine, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Renata Marques de Melo
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (UNESP), Av. Engenheiro Francisco José Longo,777. 12245000, São José Dos Campos, São Paulo, Brazil
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Kruzic JJ, Hoffman M, Arsecularatne JA. Fatigue and wear of human tooth enamel: A review. J Mech Behav Biomed Mater 2023; 138:105574. [PMID: 36473402 DOI: 10.1016/j.jmbbm.2022.105574] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/14/2022] [Accepted: 11/15/2022] [Indexed: 11/21/2022]
Abstract
Human tooth enamel must withstand the cyclic contact forces, wear, and corrosion processes involved with typical oral functions. Furthermore, unlike other human tissues, dental enamel does not have a significant capacity for healing or self-repair and thus the longevity of natural teeth in the oral environment depends to a large degree on the fatigue and wear properties of enamel. The purpose of this review is to provide an overview of our understanding of the fatigue and wear mechanisms of human enamel and how they relate to in vivo observations of tooth damage in the complex oral environment. A key finding of this review is that fatigue and wear processes are closely related. For example, the presence of abrasive wear particles significantly lowers the forces needed to initiate contact fatigue cracking while subsurface fatigue crack propagation drives key delamination wear mechanisms during attrition or attrition-corrosion of enamel. Furthermore, this review seeks to bring a materials science and mechanical engineering perspective to fatigue and wear phenomena. In this regard, we see developing a mechanistic description of fatigue and wear, and understanding the interconnectivity of the processes, as essential for successfully modelling enamel fatigue and wear damage and developing strategies and treatments to improve the longevity of our natural teeth. Furthermore, we anticipate that this review will stimulate ideas for extending the lifetime of the natural tooth structure and will help highlight where our understanding is too limited and where additional research into fatigue and wear of human tooth enamel is warranted.
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Affiliation(s)
- Jamie J Kruzic
- School of Mechanical and Manufacturing Engineering, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia.
| | - Mark Hoffman
- School of Engineering, University of Newcastle, Callaghan NSW 2308, Australia; School of Materials Science and Engineering, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia
| | - Joseph A Arsecularatne
- School of Mechanical and Manufacturing Engineering, University of New South Wales (UNSW Sydney), Sydney NSW 2052, Australia
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A brief review on fatigue test of ceramic and some related matters in Dentistry. J Mech Behav Biomed Mater 2023; 138:105607. [PMID: 36549251 DOI: 10.1016/j.jmbbm.2022.105607] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 11/28/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022]
Abstract
The characteristics of dental ceramics have been extensively studied over the years to provide highly qualified materials for use in prosthetic restorations. The ability to adhere to dental substrates, outstanding aesthetics (translucency, color, and substrate masking ability) and improved mechanical properties provide these materials with optical features and high strength to withstand masticatory stimuli. Different classifications are adopted, and it is generally considered that glass-ceramics have better optical characteristics due to the high glass content, and polycrystalline ceramics have superior strength favored by their densified and organized crystals, hampering crack growth. This knowledge was largely built-up during years of scientific research through different testing methodologies, but mainly employing static loads. It is important to not only take into account the intensity of loads that these materials will be exposed to, but also the effect of the intermittence of cyclic load application leading to mechanical fatigue and the influence of factors related to the crack origin and their propagation under this condition. Furthermore, the bonding surface of ceramic restorations requires surface treatments that improve the bond strength to luting agents; however, these treatments require caution because of their potential to produce defects and affect the structural behavior. Moreover, ceramic restorations often require internal adjustments for proper seating or external adjustments for fitting the occlusal contact with the antagonist. In this sense, finishing/polishing protocols may alter the defect population, as luting agents may also interact by filling in the superficial defects on the restoration intaglio surface. Thus, the balance among all these factors will define the performance of a restorative setup, as well as the posterior exposure to the humid environment and the masticatory stimuli (cyclical loading), which may favor developing slow and subcritical growth of cracks in ceramic materials and the degradation of the bond interface. Therefore, it is essential that the concepts which explain the fatigue mechanism are understood, as well as the crack propagation and failure patterns of restorative ceramic materials.
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Li W, Ding Q, Sun F, Liu B, Yuan F, Zhang L, Bao R, Gu J, Lin Y. Fatigue behavior of zirconia with microgrooved surfaces produced using femtosecond laser. Lasers Med Sci 2023; 38:33. [PMID: 36598586 DOI: 10.1007/s10103-022-03679-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 11/19/2022] [Indexed: 01/05/2023]
Abstract
Femtosecond laser is a promising surface treatment tool for zirconia implant. In this study, the fatigue behavior of zirconia specimens with microgrooved surfaces formed by femtosecond laser is reported. One hundred sixty CAD/CAM zirconia bars (20 mm × 4 mm × 1.4 mm) were evenly divided into four groups with different surface: as sintered; sandblasted with 110 μm Al2O3; femtosecond laser produced microgrooves having 50 μm width, 30 μm depth, and 100 μm pitch; microgrooves having 30 μm width, 20 μm depth, and 60 μm pitch. The femtosecond laser formed micro/nanostructured microgrooves with precise size on zirconia surfaces. XRD analysis indicated that microgrooved surface showed no obvious tetragonal-to-monoclinic phase transformation. The fatigue strength of sandblasted specimens (728 MPa) was significantly higher than that of as sintered specimens (570 MPa). However, the fatigue strength of specimens with microgrooved surface decreased to about 360-380 MPa. The results suggest femtosecond laser is an effective technique to regulate the surface microtopography of zirconia, while further investigations are needed to improve its fatigue behavior.
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Affiliation(s)
- Wenjin Li
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing Key Laboratory of Digital Stomatology, Beijing, 100081, China
| | - Qian Ding
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing Key Laboratory of Digital Stomatology, Beijing, 100081, China
| | - Fengbo Sun
- School of Materials Science and Engineering, Tsinghua University, 100084, Beijing, China
| | - Binchao Liu
- School of Aeronautic Science and Engineering, Beihang University, 100191, Beijing, China
| | - Fusong Yuan
- Center of Digital Dentistry, Peking University School and Hospital of Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing Key Laboratory of Digital Stomatology, Research Center of Engineering and Technology for Digital Dentistry, Ministry of Health, Beijing, 100081, China
| | - Lei Zhang
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing Key Laboratory of Digital Stomatology, Beijing, 100081, China.
| | - Rui Bao
- School of Aeronautic Science and Engineering, Beihang University, 100191, Beijing, China
| | - Jinghua Gu
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Yuanhua Lin
- School of Materials Science and Engineering, Tsinghua University, 100084, Beijing, China
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Chen Y, Maghami E, Bai X, Huang C, Pow EHN, Tsoi JKH. Which dentine analogue material can replace human dentine for crown fatigue test? Dent Mater 2023; 39:86-100. [PMID: 36503862 DOI: 10.1016/j.dental.2022.11.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/19/2022] [Accepted: 11/25/2022] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To seek dentine analogue materials in combined experimental, analytical, and numerical approaches on the mechanical properties and fatigue behaviours that could replace human dentine in a crown fatigue laboratory test. METHODS A woven glass fibre-filled epoxy (NEMA grade G10; G10) and a glass fibre-reinforced polyamide-nylon (30% glass fibre reinforced polyamide-nylon 6,6; RPN) were investigated and compared with human dentine (HD). Flexural strength and elastic modulus (n = 10) were tested on beam-shaped specimens via three-point bending, while indentation hardness (n = 3) was tested after fracture. Abutment substrates of G10, RPN and HD were prepared and resin-bonded with monolithic lithium disilicate crowns (n = 10), then subjected to wet cyclic loading in a step-stress manner (500 N initial load, 100 N step size, 100,000 cycles per step, 20 Hz frequency). Data were statistically analysed using Kruskal-Wallis one-way ANOVA followed by post-hoc comparisons (α = 0.05). Survival probability estimation was performed by Mantel-Cox Log-Rank test with 95% confidence intervals. The fatigue failure load (FFL) and the number of cycles until failure (NCF) were evaluated with Weibull statistics. Finite Element Models of the fatigue test were established for stress distribution analysis and lifetime prediction. Fractographic observations were qualitatively analysed. RESULTS The flexural strength of HD (164.27 ± 14.24 MPa), G10 (116.48 ± 5.93 MPa), and RPN (86.73 ± 3.56 MPa) were significantly different (p < 0.001), while no significant difference was observed in their flexural moduli (p = 0.377) and the indentation hardness between HD and RPN (p = 0.749). The wet cyclic fatigue test revealed comparable mean FFL and NCF of G10 and RPN to HD (p = 0.237 and 0.294, respectively) and similar survival probabilities for the three groups (p = 0.055). However, RPN promotes higher stability and lower deviation of fatigue test results than G10 in Weibull analysis and FEA. SIGNIFICANCE Even though dentine analogue materials might exhibit similar elastic properties and fatigue performance to human dentine, different reliabilities of fatigue on crown-dentine analogues were shown. RPN seems to be a better substrate that could provide higher reliability and predictability of laboratory study results.
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Affiliation(s)
- Yanning Chen
- Dental Materials Science, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - Ebrahim Maghami
- Department of Mechanical Engineering and Mechanics, College of Engineering, Drexel University, Philadelphia, PA 19104, USA
| | - Xuedong Bai
- Dental Materials Science, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - Cui Huang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory for Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Edmond Ho Nang Pow
- Prosthodontics, Restorative Dental Sciences, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - James Kit Hon Tsoi
- Dental Materials Science, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
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İrem DÖ, Cömert ZY, Alpkılıç DŞ, Keleşoğlu E, İşler Değer S. The Effect of Preceramic Soldering on Fracture Resistance of 4-Unit Zirconia Fixed Dental Prostheses. J Prosthodont 2022; 31:815-821. [PMID: 35118772 DOI: 10.1111/jopr.13488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 01/25/2022] [Indexed: 01/04/2023] Open
Abstract
PURPOSE Preceramic soldering of zirconia may deliver better fitting restorations. However, there is not sufficient evidence regarding the influence of preceramic soldering of zirconia restorations on mechanical strength. The aim of this study was to evaluate the effect of preceramic soldering on the fracture load of 4-unit zirconia fixed dental prostheses (FDPs). MATERIALS AND METHODS Eighty samples of 4-unit FDPs between maxillary right first premolar and maxillary right second molar were prepared and two restorative materials were used as a framework (Z) and monolithic restoration (M). The samples were divided into two subgroups as control (C) and study (S). The restorations of study groups (S) were divided into two pieces and soldered with a bonding material (DCM HotBond Zirkon). The groups were divided into two subgroups for thermal cycle (T) application. After soldering and thermal cycling application, 4-point bending test was applied to the samples at a cross-head speed of 1 mm/min in a universal testing machine and the fracture load was recorded. The data was analyzed statistically, and the level of significance was set at α = 0.001. RESULTS Statistically significant differences were found among the groups, based on the results of maximum failure loads (p < 0.001). The highest mean failure load was observed in the ZCT(-) group (1094.1 + 139.77 N), while the lowest mean failure load was obtained in the ZST(+) group (627.7 + 82.14 N). No significant difference was found among the groups MC and MS, MC, and ZC groups (p > 0.001). Thermal aging application caused lower fracture resistance in control and soldering groups (p < 0.001). CONCLUSIONS The preceramic soldering applications affected zirconia group negatively. However, the values were above the clinically acceptable static load bearing capacity for posterior teeth. Soldering did not cause a statistically significant difference for the fracture strengths of monolithic zirconia groups. Thermal cycling affected the fracture strength of zirconia and monolithic zirconia restorations negatively.
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Affiliation(s)
| | | | - Dilara Şeyma Alpkılıç
- Department of Prosthodontics, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
| | - Ergün Keleşoğlu
- Faculty of Materials Science and Technologies, Turkish-German University, Istanbul, Turkey
| | - Sabire İşler Değer
- Department of Prosthodontics, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
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36
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Alves LMM, Rodrigues CDS, Ramos NDC, Buizastrow J, Campos TMB, Bottino MA, Zhang Y, Melo RMD. Silica infiltration on translucent zirconia restorations: Effects on the antagonist wear and survivability. Dent Mater 2022; 38:2084-2095. [PMID: 36446649 PMCID: PMC9928576 DOI: 10.1016/j.dental.2022.11.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 09/23/2022] [Accepted: 11/11/2022] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To assess potential antagonist wear and survival probability of silica-infiltrated zirconia compared to glass-graded, glazed, and polished zirconia. METHODS Table top restorations made of 3Y-TZP (3Y), 5Y-PSZ (5Y), and lithium disilicate (LD) were bonded onto epoxy resin preparations. Each zirconia was divided into five groups according to the surface treatment: polishing; glaze; polishing-glaze; glass infiltration; and silica infiltration. The LD restorations received a glaze layer. Specimens were subjected to sliding fatigue wear using a steatite antagonist (1.25 ×106 cycles, 200 N). The presence of cracks, fractures, and/or debonding was checked every one/third of the total number of cycles was completed. Roughness, microstructural, Scanning electron microscopy, wear and residual stress analyses were conducted. Kaplan-Meier, Mantel-Cox (log-rank) and ANOVA tests were performed for statistical analyses. RESULTS The survival probability was different among the groups. Silica infiltration and polishing-glaze led to lower volume loss than glaze and glass-infiltration. Difference was observed for roughness among the zirconia and surface treatment, while lithium disilicate presented similar roughness compared to both glazed zirconia. Scanning electron microscopy revealed the removal of the surface treatment after sliding fatigue wear in all groups. Compressive stress was detected on 3Y surfaces, while tensile stress was observed on 5Y. SIGNIFICANCE 3Y and 5Y zirconia behaved similarly regarding antagonist wear, presenting higher antagonist wear than the glass ceramic. Silica-infiltrated and polished-glazed zirconia produced lower antagonist volume loss than glazed and glass-infiltrated zirconia. Silica-infiltrated 3Y and lithium disilicate restorations were the only groups to show survival probabilities lower than 85%.
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Affiliation(s)
- Larissa Marcia Martins Alves
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil; Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 1st Ave., New York, NY 10010, United States
| | - Camila da Silva Rodrigues
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil; Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 1st Ave., New York, NY 10010, United States
| | - Nathalia de Carvalho Ramos
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil
| | - Jeff Buizastrow
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 1st Ave., New York, NY 10010, United States
| | - Tiago Moreira Bastos Campos
- Department of Physics, Aeronautics Technological Institute (ITA), Praça Marechal Eduardo Gomes, 50, 12228-900 São José dos Campos, SP, Brazil
| | - Marco Antonio Bottino
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, PA 19104, United States
| | - Renata Marques de Melo
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil.
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da Silva SEG, de Araújo GM, Souza KB, Moura DMD, Aurélio IL, May LG, Vila-Nova TEL, Zhang Y, de Assunção E Souza RO. Biaxial flexure strength and physicochemical characterization of a CAD/CAM lithium disilicate ceramic: effect of etching time, silane, and adhesive applications. Clin Oral Investig 2022; 26:6753-6763. [PMID: 35980474 PMCID: PMC9902029 DOI: 10.1007/s00784-022-04635-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 07/12/2022] [Indexed: 01/21/2023]
Abstract
OBJECTIVE To evaluate the effect of different acid etching time and bonding agent (silane and/or adhesive system) on biaxial flexural strength and physico-chemical properties of a lithium disilicate ceramic. MATERIAL AND METHODS One hundred twenty ceramic discs were made and divided into 8 groups (n = 15) according to factors "etching time" (20 and 120 s) with hydrofluoric acid (HF) and "bonding agent" (C, no bonding agent; S, silane, A, adhesive; and SA, silane + adhesive). After surface treatment, a resin cement layer was applied to the surface and all specimens were subjected to biaxial flexural strength (BFS) test with treated surfaces loaded in tension (1 mm/min). The Weibull analyses and complementary analyses were also performed. Statistical analysis was done with 2-way ANOVA and the Tukey test (α = 0.05). RESULTS ANOVA revealed that the factors "etching time" (p = 0.0003) and "bonding agent" (p = 0.007) were statistically significant. In the overall analysis, the HF120S group (272.02 ± 35.30A MPa) presented significantly higher BFS than that of HF120C (218.45 ± 17.15CD MPa) and HF20S (228.40 ± 37.83BCDMPa). On the other hand, the HF20A group (208.92 ± 31.16D MPa) had significantly lower BFS than HF120S (272.02 ± 35.30A), HF120A (254.42 ± 26.87ABC) and HF120SA (259.30 ± 36.55AB) groups (Tukey). The Weibull modulus (m) of all groups was significantly different from each other (p = 0.000). CONCLUSIONS Regardless of etching time, the application of silane alone is sufficient to increase the flexural strength of glass ceramic, eliminating the need for the application of adhesive systems. Moreover, if only silane or adhesive is applied, 120-s HF application should increase the flexural resistance of the lithium disilicate ceramic. CLINICAL SIGNIFICANCE Applications of adhesive systems after silanization can be suppressed from the surface treatment protocol of glass ceramics, since it does not improve their mechanical strength.
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Affiliation(s)
- Sarah Emille Gomes da Silva
- Department of Dentistry, Federal University of Rio Grande Do Norte (UFRN), Av. Salgado FilhoLagoa Nova, Natal, RN, CEP, 178759056-000, Brazil
| | - Gabriela Monteiro de Araújo
- Department of Dentistry, Oral Science, Federal University of Rio Grande Do Norte (UFRN), Av. Salgado FilhoLagoa Nova, Natal, RN. CEP, 178759056-000, Brazil
| | - Karina Barbosa Souza
- Institute of Science and Technology, Univ Estadual Paulista - UNESP, Francisco Jose Longo, Av. Eng, Sao Jose dos Campos, SP, 777, Brazil
| | - Dayanne Monielle Duarte Moura
- Department of Dentistry, State University of Rio Grande Do Norte (UERN), Rua Almino Afonso, 478 - Centro - Mossoró/RN CEP: 59.610-210, Rio, Brazil
| | - Iana Lamadrid Aurélio
- Department of Restorative Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | - Liliana Gressler May
- Department of Restorative Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | | | - Yu Zhang
- School of Dental Medicine, Department of Preventive and Restorative, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Rodrigo Othávio de Assunção E Souza
- Department of Dentistry, Federal University of Rio Grande Do Norte (UFRN), Av. Salgado FilhoLagoa Nova, Natal, RN, CEP, 178759056-000, Brazil.
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Alves L, Rodrigues C, Vardhaman S, Saunders C, Schneider J, Lawn B, Zhang Y. Exploring Ductility in Dental Ceramics. J Dent Res 2022; 101:1467-1473. [PMID: 35689403 PMCID: PMC9608091 DOI: 10.1177/00220345221100409] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Two damage regimes-"brittle" and "ductile"-have been identified in the literature on ceramic grinding, machining, grit blasting, and wear. In the brittle regime, the damage mechanism is essentially crack formation, while in the ductile region, it is quasiplasticity. Onset of the brittle mode poses the greater threat to strength, so it becomes important to understand the mechanics of ductile-brittle thresholds in these materials. Controlled microcontact tests with a sharp indenter are employed to establish such thresholds for a suite of contemporary computer-aided design/computer-aided manufacturing dental ceramics. Plots of flexural strength S versus indentation load P show a steep decline beyond the threshold, consistent with well-established contact mechanics relations. Threshold dimensions occur on a scale of order 1 µm and contact load of order 1 N, values pertinent to practical grit finishing protocols. The ductile side of ceramic shaping is accessed by reducing grit sizes, applied loads, and depths of cut below critical levels. It is advocated that critical conditions for ductile shaping may be most readily quantified on analogous S(P) plots, but with appropriate machining variable (grit size, depths of cut, infeed rate) replacing load P. Working in the ductile region offers the promise of compelling time and cost economies in prosthesis fabrication and preparation.
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Affiliation(s)
- L.M.M. Alves
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University, São José dos Campos, SP, Brazil
| | - C.S. Rodrigues
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University, São José dos Campos, SP, Brazil
| | - S. Vardhaman
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - C. Saunders
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA
| | - J.M. Schneider
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA
| | - B.R. Lawn
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Y. Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Luft RL, da Rosa LS, Machado PS, Valandro LF, Sarkis-Onofre R, Pereira GKR, Bacchi A. Influence of connector cross-sectional geometry on the load-bearing capacity under fatigue of implant-supported zirconia fixed partial prosthesis. J Prosthet Dent 2022; 128:1335.e1-1335.e8. [DOI: 10.1016/j.prosdent.2022.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 10/13/2022] [Accepted: 10/13/2022] [Indexed: 11/19/2022]
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Channarong W, Lohawiboonkij N, Jaleyasuthumkul P, Ketpan K, Duangrattanaprathip N, Wayakanon K. Fracture resistance of bonded ceramic overlay restorations prepared in various designs. Sci Rep 2022; 12:16599. [PMID: 36198863 PMCID: PMC9534891 DOI: 10.1038/s41598-022-21167-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 09/23/2022] [Indexed: 11/26/2022] Open
Abstract
This study investigates fracture resistance of adhesive ceramic overlays of various designs. Forty-eight upper premolar teeth were divided into eight groups. The variations were: shoulder margins on the buccal and lingual surfaces with axial wall heights of 1, 2, or 3 mm; one shoulder margin with axial wall height of 1, 2, or 3 mm on the lingual surface and one contrabevel margin on the buccal surface; contrabevel margins on the buccal and lingual surfaces; and a control of sound teeth. Overlays were designed and fabricated with CAD/CAM using zirconia-reinforced lithium disilicate ceramic and bonded with resin cement. Samples underwent thermocycling and dynamic fatigue equivalent to 6 months of use. Compressive loading was applied until fracture, and fracture mode was analyzed. Results showed no statistical difference in fracture resistance between designs, and the fracture pattern of most was involvement of pulp tissue and below the CEJ. Fracture resistance of the restored teeth was also not statistically different from the control. All control fractures were within the dentin and above the CEJ. Overlay restorations were therefore effective in strengthening damaged teeth and imparting fracture resistance equal to sound teeth, and axial wall heights and margin types did not influence this result.
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Affiliation(s)
| | | | | | - Kittipong Ketpan
- Department of Restorative Dentistry, Naresuan University, Phitsanulok, Thailand
| | | | - Kornchanok Wayakanon
- Department of Restorative Dentistry, Naresuan University, Phitsanulok, Thailand.
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Velho HC, da Rosa LS, Temp RW, Cocco FM, Pereira GKR, May LG, Valandro LF. Adhesive application after ceramic surface treatment is detrimental to load-bearing capacity under fatigue of a lithium disilicate glass-ceramic. J Mech Behav Biomed Mater 2022; 135:105453. [PMID: 36126505 DOI: 10.1016/j.jmbbm.2022.105453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 08/30/2022] [Accepted: 09/03/2022] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To evaluate whether an adhesive application after surface treatment on a lithium disilicate ceramic (LD) has an influence on its load-bearing capacity under fatigue. METHODS LD discs (Ø= 10 mm; thickness= 1 mm) were allocated into 8 groups (n= 15), considering 3 factors: "ceramic surface treatment" - HF: hydrofluoric acid + universal primer application; or MEP: single-component ceramic primer; "adhesive application" - with or without; and "aging protocol" - baseline: 24 h to 7 days; or aging: 180 days of storage + 25,000 thermal cycles. The LD discs were adhesively bonded to glass fiber-reinforced epoxy resin discs (Ø= 10 mm; thickness= 2 mm) and stored according to the condition and each group. Cyclic fatigue testing (initial load= 100 N; step size= 100 N until600 N and after step size= 25 N to failure; 10,000 cycles/step; 20 Hz frequency) was performed. Fractographic and adhesive interface analyzes were also performed. The collected data were then analyzed by Kaplan Meier and Mantel-Cox tests and One-way ANOVA. RESULTS The adhesive application in the baseline condition had no influence on the load-bearing capacity under fatigue when the HF surface treatment was performed, however, adhesive application for the MEP treatment led to worse results than without it. The adhesive application in the aged condition showed worse fatigue outcomes for both treatments. All specimens presented radial cracks. MEP treatment followed by adhesive application presented the thickest luting layer. CONCLUSION The adhesive application after surface treatments of a lithium disilicate glass-ceramic is detrimental to its load-bearing capacity under fatigue when adhesively luted onto a supporting substrate.
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Affiliation(s)
- Helder Callegaro Velho
- Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Lucas Saldanha da Rosa
- Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Renatta Wrasse Temp
- Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Fernanda Maidana Cocco
- Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Gabriel Kalil Rocha Pereira
- Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Liliana Gressler May
- Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Luiz Felipe Valandro
- 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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Thickness and internal adjustment of monolithic resin composite milled crowns: Effect on the load-bearing capacity under fatigue. J Mech Behav Biomed Mater 2022; 134:105407. [DOI: 10.1016/j.jmbbm.2022.105407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/23/2022] [Accepted: 07/26/2022] [Indexed: 11/24/2022]
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Frasheri I, Hickel R, Manhart J, Diegritz C, Folwaczny M, Fotiadou C. Longevity of gold restorations in posterior teeth: A retrospective study up to 10-years. J Dent 2022; 124:104235. [PMID: 35870735 DOI: 10.1016/j.jdent.2022.104235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 07/11/2022] [Accepted: 07/14/2022] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE In this retrospective clinical study, we investigated the long-term survival and success of indirect gold restorations, placed by undergraduate students. MATERIAL AND METHODS The study included 72 gold restorations in 45 patients, placed in a five-year period between 2009 and 2013. Two experienced dentists performed the evaluation following the FDI criteria after 5 to 10 years. Kaplan-Meier test was used for longevity analysis of success and survival. Data were tested for normality with Shapiro-Wilk test. Cox regression analysis, with significance level appointed at p ≤ .05, was performed using success and survival of restorations as dependent variables. Annual failure rates (AFRs) were calculated. RESULTS Overall, 72 indirect gold restorations prepared in posterior teeth were assessed, with an observation time from 63 months to 117 months. The mean service time was 88.1 months and the median 87 months. No failures, but 2 repairs, were observed during the first five years. From 5 to 10 years 1 replacement and 1 more repair occurred. The survival and success rates of gold restorations were calculated at 9 years with 98.6% and 91%, respectively. Restorations placed on premolars had higher survival and success rates compared to molars. Three cases were categorized as repairs: in two cases, a root canal treatment was needed and, in one other, an occlusal perforation of the restoration was observed. CONCLUSIONS Posterior indirect gold restorations placed by dental undergraduate students showed a highly predictable clinical performance in terms of success and survival. These results are comparable with survival rates reported in literature for restorations cemented in general dental practices. CLINICAL SIGNIFICANCE Casted gold restorations placed from dental students in an undergraduate setting show high survival rates, similar to professional dentists.
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Affiliation(s)
- Iris Frasheri
- Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians-University Munich, Goethestr. 70, Munich 80336, Germany.
| | - Reinhard Hickel
- Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians-University Munich, Goethestr. 70, Munich 80336, Germany
| | - Juergen Manhart
- Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians-University Munich, Goethestr. 70, Munich 80336, Germany
| | - Christian Diegritz
- Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians-University Munich, Goethestr. 70, Munich 80336, Germany
| | - Matthias Folwaczny
- Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians-University Munich, Goethestr. 70, Munich 80336, Germany
| | - Christina Fotiadou
- Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians-University Munich, Goethestr. 70, Munich 80336, Germany
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Does adhesive luting promote improved fatigue performance of lithium disilicate simplified crowns? J Mech Behav Biomed Mater 2022; 134:105373. [PMID: 35868064 DOI: 10.1016/j.jmbbm.2022.105373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 07/14/2022] [Indexed: 11/22/2022]
Abstract
The present study aimed to determine the influence of adhesive luting on the fatigue mechanical properties of simplified lithium disilicate crowns luted to dentin analogues preparations, and to compare two different approaches of simulation of a non-adhesive luting procedure. To this end, 30 prosthetic preparations of glass fiber-filled epoxy resin used as dentin analogues were milled and lithium disilicate crowns were pressed (1.5 mm thickness), which were allocated into three different groups: resin cement (RC), resin cement isolated by paraffin oil (RCI) and zinc phosphate cement (ZP). For luting procedures, the ceramic crowns of the RC and RCI groups had their internal surface treated with 5% hydrofluoric acid and universal primer. Afterwards, a thin layer of paraffin oil was applied onto the ceramic crown intaglio surface in the RCI group. The dentin analogues were treated with 10% hydrofluoric acid, followed by primer application and luting as recommended by the manufacturer. No previous surface treatments were performed for the ZP group, and the cement was applied as recommended. The fatigue test was run under cyclic fatigue (load 400-2000 N, step-size 100 N, 15,000 cycles/step, frequency 20 Hz) until failure detection (radial crack) by transillumination. The fatigue failure load (FFL), number of cycles until failure (CFF), and survival rate in each testing step were recorded. The RC group presented a higher FFL, CFF and survival rate compared to the other groups (p < 0.001), which were statistically equal to each other (p > 0.05). Weibull analysis detected no difference between groups for the Weibull module. Therefore, loss of adhesion between the evaluated substrates induces a significant reduction in load-bearing capacity under fatigue of the lithium disilicate crowns, strengthening the strong-importance of long-lasting adhesion for crown's survival. In addition, different methods for the simulation of non-adhesive conditions induce the same performance in the explored outcomes, confirming that both are valid approaches for laboratory studies.
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Analysis of microstructure and fatigue of cast versus selective laser-melted dental Co-Cr alloy. J Prosthet Dent 2022; 128:218.e1-218.e7. [PMID: 35786348 DOI: 10.1016/j.prosdent.2022.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 05/24/2022] [Accepted: 05/24/2022] [Indexed: 11/22/2022]
Abstract
STATEMENT OF PROBLEM The forces exerted on teeth and prostheses during mastication are repeated and dynamic, resulting in fatigue damage to dental prostheses. Most fractures of dental restorations are fatigue failure. The 4-point bend fatigue behavior of Co-Cr-Mo-W alloys manufactured by investment casting (CAST) and selective laser melting (SLM) has received little attention. PURPOSE The purpose of this in vitro study was to evaluate the 4-point bend fatigue property of dental Co-Cr alloys and determine the relationship between microstructure and the 4-point bend fatigue property of Co-Cr alloys created by traditional casting and SLM. These can guide the use of Co-Cr alloy in dentistry. MATERIAL AND METHODS Co-Cr-Mo-W alloys were fabricated with a dimension of 45×2×2 mm by investment casting and SLM. The 3-point bend test measured the ultimate bend strength with 3 specimens in each group. The 4-point bend fatigue test evaluated the fatigue life under various stresses, with 6 specimens in each group. The specimens were mechanically ground, polished, and electrochemically etched. Scanning electron microscopy was used to identify the microstructures of both etched specimens and fracture surfaces. X-ray diffraction investigations were used to determine the phases. Significant differences in the bend strength were analyzed by using the independent samples t test (α=.05), and the fatigue test was analyzed with ANCOVA (α=.05). RESULTS The mean ±standard deviation bend strength of SLM specimens was 1837 ±3 MPa, higher than the 1200 ±6 MPa for CAST specimens (P<.05). The maximum bend stress of the SLM specimens without fatigue failure was 735 MPa, which was statistically higher than the 394 MPa for CAST specimens (P<.05). The microstructure characteristics of the SLM alloy contributed to its excellent fatigue performance. In SLM alloy, the γ phase constituted the majority with some ε and Laves phases, while the cast alloy possessed higher ε and Laves phases. The grains of SLM alloy were equiaxed and fine, and the second phases were fine and dispersive. In contrast, the cast alloy possessed clear dendrites, and the second phases were sizable. CONCLUSIONS The SLM dental Co-Cr-Mo-W alloy had statistically better 4-point bend fatigue properties than cast alloy, which was associated with an improved microstructure.
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Al-Ali AMAH, Khalifa N, Hadj-Hamou A, Sheela S, El-Damanhoury HM. Effect of Thickness and Bonding Technique on Fatigue and Fracture Resistance of Feldspathic Ultra-Thin Laminate Veneers. Eur J Dent 2022. [PMID: 35728607 DOI: 10.1055/s-0042-1745770] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
OBJECTIVES To evaluate the fatigue and fracture resistance of ultra-thin laminate veneers (UTLV) with two different thicknesses and two different bonding protocols. MATERIALS AND METHODS A total of 64 flat enamel surfaces were assigned to either 0.2 or 0.4 mm UTLV. The UTLV were further subdivided and assigned to one of two bonding techniques: adhesive resin cement(RC( or preheated restorative resin composite (HC) (n = 16). Eight samples were fatigued with 750,000 mechanical cycles and 8,000 thermal cycles between 5 and 55°C in a chewing simulator, and the failure mode was evaluated using a stereomicroscope and SEM. The other eight samples from each group were loaded to failure in a universal testing machine to test the fracture resistance. Fisher's exact Probability test was used to analyze the fatigue test results, and two-way analysis of variance and Bonferroni's test were used to analyze the fracture resistance test results. RESULTS The difference in fatigue resistance between failure proportions in different groups was statistically different (p < 0.05). The 0.4-mm-thick UTLV had similar results regardless of the bonding technique, while 0.2-mm-thick UTLV only showed comparable results when cemented with preheated HC. No statistically significant difference was found in fracture resistance between the tested groups (p > 0.05). CONCLUSION The Bonding technique and the thickness of the UTLV had impacted fatigue resistance but had no significant effect on the fracture resistance. bonding of UTLV with preheated composite increases their fatigue resistance. Different testing approaches delivered different results.
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Affiliation(s)
- Amna Mohamed Ahmed Hassan Al-Ali
- Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | - Nadia Khalifa
- Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | - Amir Hadj-Hamou
- Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | - Soumya Sheela
- Dental Biomaterials Research Laboratory, Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Hatem M El-Damanhoury
- Department of Preventive and Restorative Dentistry, College of Dental Medicine, University Dental Hospital, University of Sharjah, Sharjah, United Arab Emirates
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Lawn BR, Huang H, Lu M, Borrero-López Ó, Zhang Y. Threshold damage mechanisms in brittle solids and their impact on advanced technologies. ACTA MATERIALIA 2022; 232:117921. [PMID: 37599815 PMCID: PMC10438830 DOI: 10.1016/j.actamat.2022.117921] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/22/2023]
Abstract
Threshold damage mechanisms in brittle covalent-ionic solids are outlined. Fracture and deformation modes are analyzed in terms of classical contact mechanics. Distinctions are made between brittle, ductile and quasiplastic mechanisms in both axial and translational contact. Special attention is devoted to the relatively unexplored subthreshold region where macrofracture is largely suppressed, a region of increasing relevance in the relentless move toward ever smaller devices and precision shaping technologies in the manufacturing sector. Cross-section micrographic images illustrate the fundamental nature of shear events within the hardness deformation zone responsible for crack initiation and propagation. Basic analytical relations for the strengths of surfaces with contact-induced damage in the postthreshold and subthreshold regions are presented, with emphasis on concept rather than fine detail. Strength data for a prototypical brittle material after sharp-indenter damage are presented to highlight the vital role of microstructure in determining transitions between brittle and quasiplastic responses. Pristine defect-free solids are shown to be highly vulnerable to contact damage, even in the subthreshold region. Heterogeneous solids with granular microstructures have lower initial strengths, but are more flaw tolerant. Brittle solids are also highly susceptible to degradation by surface removal processes in wear and machining settings, to a large extent depending again on microstructure. Implications of these findings concerning advanced technological applications of covalent-ionic solids are discussed.
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Affiliation(s)
- Brian R. Lawn
- Material Measurement Laboratory, National Institute of Standards and Technology, MD 20899, USA
- School of Mechanical and Mining Engineering, The University of Queensland, QLD 4072, Australia
| | - Han Huang
- School of Mechanical and Mining Engineering, The University of Queensland, QLD 4072, Australia
| | - Mingyuan Lu
- School of Mechanical and Mining Engineering, The University of Queensland, QLD 4072, Australia
| | - Óscar Borrero-López
- Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura, 06006 Badajoz, Spain
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Vasiliu RD, Uțu ID, Rusu L, Boloș A, Porojan L. Fractographic and Microhardness Evaluation of All-Ceramic Hot-Pressed and CAD/CAM Restorations after Hydrothermal Aging. MATERIALS (BASEL, SWITZERLAND) 2022; 15:3987. [PMID: 35683294 PMCID: PMC9182156 DOI: 10.3390/ma15113987] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/29/2022] [Accepted: 06/02/2022] [Indexed: 12/04/2022]
Abstract
All-ceramic dental restorations have great advantages, such as highly esthetical properties, a less complex fabrication, and a similar abrasion resistance to enamel. Despite these advantages, ceramic materials are more prone to fracture due to their brittle microstructure. The main aim of this in vitro study was to determine the difference in hot-pressed and milled glass-ceramic mechanical properties such as fracture resistance and microhardness (VHN). Four types of ceramics, two hot-pressed and two milled, feldspathic glass-ceramics and zirconia-reinforced glass-ceramics were selected in this study and tested using the static loading test and Vicker’s testing. Hydrothermal aging, consisting of different baths with temperatures between 5 degrees Celsius and 55 degrees Celsius, was chosen as the in vitro aging method. Statistical analyses are performed using SPSS Statistics software at a significance level of p < 0.05. Micro-hardness values decrease after hydrothermal aging. The static loading test reveals a significant difference between the feldspathic hot-pressed glass-ceramic, which fractures at lower forces, and milled zirconia-reinforced lithium silicate glass-ceramic, which fractures at greater forces (N). Fractographic analysis of the fractured fragments resulted in the static loading test revealing different surface features about the crack origins and propagations under a stereomicroscope.
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Affiliation(s)
- Roxana Diana Vasiliu
- Center for Advanced Technologies in Dental Prosthodontics, Department of Dental Prostheses Technology (Dental Technology), Faculty of Dental Medicine, “Victor Babeș” University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania;
| | - Ion-Dragoș Uțu
- Departament of Materials Engineering and Fabrication, University of Politehnică Timişoara, Bd. Mihai Viteazul nr.1, 300222 Timişoara, Romania;
| | - Lucian Rusu
- Department Mechanics and Vibrations, Faculty of Mechanical Engineering, Politehnica University, 1 Mihai Viteazu Street, 300222 Timisoara, Romania;
| | - Adrian Boloș
- Department of Oral Rehabilitation (Dental Technique), Faculty of Dental Medicine, “Victor Babeș” University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania;
| | - Liliana Porojan
- Center for Advanced Technologies in Dental Prosthodontics, Department of Dental Prostheses Technology (Dental Technology), Faculty of Dental Medicine, “Victor Babeș” University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania;
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50
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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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