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Ilie N. Influence of surface finishing on the outcome of a 3-point bending test in polymer-based dental composits assessed by qualitative and quantitative fractography. J Mech Behav Biomed Mater 2024; 156:106607. [PMID: 38830315 DOI: 10.1016/j.jmbbm.2024.106607] [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: 04/12/2024] [Revised: 05/24/2024] [Accepted: 05/29/2024] [Indexed: 06/05/2024]
Abstract
OBJECTIVES The aim of the study was to evaluate the influence of surface finishing in three polymer-based composits (composits) on the result of a 3-point bending test using quantitative and qualitative fractography as well as microstructural characteristics. MATERIALS AND METHODS 270 rectangular specimens (n = 30) of three composits were prepared, stored and tested according to NIST No. 4877. Prior testing, the samples were subjected to three surface treatments: 1) no treatment, to preserve the oxygen inhibition layer, 2) with FEPA P1200 (ANSI equivalent grit 600) SiC paper abraded surface, and 3) polished surface. A three-point bending testing was employed, followed by quantitative (assessment of reason for failure and fracture pattern) and qualitative (fracture mirror measurements) fractography, 3D and 2D surface imaging, surface roughness, reliability and Fe-SEM analysis. The mirror radius that runs in the direction of constant stress was used to calculate the mirror constant (A) using Orr's equation. Uni- and multifactorial ANOVA, Tukey's post hoc test, and Weibull analysis was performed for statistical analysis. RESULTS Surface finishing has less influence on the fracture pattern, reliability and mechanical parameters and has no influence on the mirror constant. The amount of inorganic filler has a direct impact on flexural strength and modulus, while the ranking of materials was independent of surface treatment. Failures initiated by volume defects were the most common failure mode (77.0%) with surface defects accounting for 14.9% (edge) and 7.7% (corner). Polishing resulted in lower peak-to valley height compared to no treatment, both 3-4 times lower compared to the 600 grit treatment. The increase in roughness within the analyzed range did not lead to an increase in surface-related failures. CONCLUSIONS The clear dominance of volume defects in all examined materials as a cause of material fracture reduces the impact of roughness on the measured properties. This insight was only possible using qualitative and quantitative research fractography.
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Affiliation(s)
- Nicoleta Ilie
- Department of Conservative Dentistry, University Hospital, Ludwig-Maximilians-University, Goethestr. 70, D-80336, Munich, Germany.
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Chen Z, Zhang M, Zhang R, Hao P. Effect of the coloring liquid shade and dipping time on the color, transparency, and flexural strength of monolithic zirconia. J Prosthet Dent 2024; 132:229.e1-229.e8. [PMID: 38604904 DOI: 10.1016/j.prosdent.2024.03.035] [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: 08/30/2023] [Revised: 03/04/2024] [Accepted: 03/05/2024] [Indexed: 04/13/2024]
Abstract
STATEMENT OF PROBLEM The impact of different coloring liquid shades and dipping times on the color, transparency, and flexural strength of monolithic zirconia ceramics is unclear. PURPOSE The purpose of this in vitro study was to evaluate the effects of different coloring liquid shades (A2, 3M2, and 5M2) and dipping times (no dipping, 30 seconds, 60 seconds, and 90 seconds) on the color difference (ΔE00), relative translucency parameter (ΔRTP00), and 3-point flexural strength (σ) of monolithic zirconia ceramics. MATERIAL AND METHODS Yttria-stabilized zirconia (3Y-TZP, 3 mol%) was cut into Ø16×1.2-mm plates (n=10) and 25×4×1.2-mm bars (n=15), which were colored using 3 shades of coloring liquid at 4 dipping times. Color coordinates were measured on a gray background by using a digital spectrophotometer with an integrating sphere attachment. The color and translucency differences were evaluated using 50:50% perceptibility (PT00 and TPT00) and acceptability (AT00 and TAT00) thresholds. The 3-point flexural strengths of the bar-shaped specimens were measured using a universal testing machine and analyzed using the Weibull distribution to calculate the Weibull modulus (m) and characteristic fracture strength (σ0). The data were analyzed with the 2-way ANOVA, Kruskal-Wallis, and LSD post hoc tests (α=.05). RESULTS Both shade and dipping time significantly affected the color and translucency of monolithic zirconia (P<.001). The ΔE00 was above the PT00 for all groups, with only 3M2-90 and A2-60 being below the AT00. The main cause of color differences was the difference in lightness. Only A2 showed ΔRTP00 below the TPT00 (A2-30 (ΔRTP00=0.26), A2-60 (ΔRTP00=0.29), and A2-90 (ΔRTP00=0.46)). All experimental groups showed translucency differences below TAT00. In addition, only the dipping time had a significant effect on the flexural strength of zirconia (P<.001). CONCLUSIONS The optical properties of monolithic zirconia ceramics were affected by the shade and dipping time of the coloring liquid. The mismatch in lightness was the main reason for the color difference. The dipping time affects the flexural strength of monolithic zirconia, whereas the shade of the coloring liquid did not seem to influence flexural strength.
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Affiliation(s)
- Zijie Chen
- Graduate student, Dental Technology, School of Stomatology, Binzhou Medical University, Yantai, PR China
| | - Mengmeng Zhang
- Graduate student, Dental Technology, School of Stomatology, Binzhou Medical University, Yantai, PR China
| | - Rimei Zhang
- Graduate student, Yantai Stomatological Hospital of Binzhou Medical University, Yantai, PR China
| | - Pengjie Hao
- Associate Professor, Department of Prosthodontics, Yantai Stomatological Hospital of Binzhou Medical University, Yantai, PR China.
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Strazzi-Sahyon HB, Campos TMB, Dos Santos C, Piza MMT, Alves LMM, Benalcazar Jalkh EB, Bergamo ETP, Tebcherani SM, Witek L, Coelho PG, Yamaguchi S, Bonfante EA. Effect of calcination on minimally processed recycled zirconia powder derived from milling waste. Dent Mater 2024:S0109-5641(24)00183-0. [PMID: 38944559 DOI: 10.1016/j.dental.2024.06.026] [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: 02/18/2024] [Revised: 06/16/2024] [Accepted: 06/18/2024] [Indexed: 07/01/2024]
Abstract
OBJECTIVE To assess the influence of calcination process on the properties of minimally processed recycled 3Y-TZP, and to compare it with its commercial counterpart. METHODS Non-milled 3Y-TZP waste was collected, fragmented and ball-milled to a granulometric < 5 µm. Half of the recycled powder was calcined at 900 °C. Recycled 3Y-TZP disks were uniaxially pressed and sintered to create two recycled groups: 1) Calcined and 2) Non-calcined to be compared with a commercial CAD/CAM milled 3Y-TZP. The microstructure of experimental groups was assessed through density (n = 6), scanning electron microscopy (n = 3) and energy-dispersive X-ray spectroscopy (n = 3); and the crystalline content was evaluated through X-ray diffraction (XRD) (n = 3). Optical and mechanical properties were investigated through reflectance tests (n = 10), and Vickers hardness, fracture toughness (n = 5), and biaxial flexural strength tests (n = 16), respectively. Fractographic analysis was performed to identify fracture origin and crack propagation. Statistical analyses were performed through ANOVA followed by Tukey´s test, and by Weibull statistics. RESULTS Particle size distribution of recycled powder revealed an average diameter of ∼1.60 µm. The relative density of all experimental groups was > 98.15 % and XRD analysis exhibited a predominance of tetragonal-phase in both recycled groups, which were similar to the crystallographic pattern of the control group. Cross-section micrographs presented flaws on the non-calcined group, and a more homogeneous microstructure for the calcined and commercial groups. Commercial samples showed lower contrast-ratio and higher translucency-parameter than the recycled groups, where non-calcined presented higher translucency-parameter and lower contrast-ratio than its calcined counterpart. The commercial group presented higher fracture toughness and characteristic strength than the recycled groups. Moreover, the calcined group exhibited higher hardness, characteristic strength, and probability of survival at higher loads than the non-calcined group. Fractographic analysis depicted the presence of microstructural flaws in the non-calcined group, which may have acted as stress-raisers and led to failures at lower flexural strengths values. SIGNIFICANCE The calcination process improved the microstructure, optical, and mechanical properties of the recycled 3Y-TZP.
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Affiliation(s)
- H B Strazzi-Sahyon
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil.
| | - T M B Campos
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil; Department of Physics, Aeronautics Technological Institute, São José dos Campos, SP, Brazil
| | - C Dos Santos
- Faculty of Technology, University of Rio de Janeiro State (UERJ - FAT), Resende, RJ, Brazil
| | - M M T Piza
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil
| | - L M M Alves
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil
| | - E B Benalcazar Jalkh
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil
| | - E T P Bergamo
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil; Biomaterials Division, New York University College of Dentistry, New York, NY, USA
| | - S M Tebcherani
- Department of Production Engineering, Federal University of Technology, Paraná, Ponta Grossa, PR, Brazil
| | - L Witek
- Biomaterials Division, New York University College of Dentistry, New York, NY, USA; Department of Biomedical Engineering, NYU Tandon School of Engineering, New York University, Brooklyn, NY, USA
| | - P G Coelho
- Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - S Yamaguchi
- Department of Dental Biomaterials, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
| | - E A Bonfante
- Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, 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:S0109-5641(24)00133-7. [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] [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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Cesar PF, Miranda RBDP, Santos KF, Scherrer SS, Zhang Y. Recent advances in dental zirconia: 15 years of material and processing evolution. Dent Mater 2024; 40:824-836. [PMID: 38521694 PMCID: PMC11098698 DOI: 10.1016/j.dental.2024.02.026] [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: 01/26/2024] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/25/2024]
Abstract
OBJECTIVES The objective was to discuss the research on zirconia published in the past 15 years to help the dental materials community understand the key properties of the types of zirconia and their clinical applications. METHODS A literature search was performed in May/2023 using Web of Science Core Collection with the term "dental zirconia". The search returned 5102 articles, which were categorized into 31 groups according to the research topic. RESULTS The current approach to improving the translucency of zirconia is to decrease the alumina content while increasing the yttria content. The resulting materials (4Y-, 5Y-, and above 5 mol% PSZs) may contain more than 50% of cubic phase, with a decrease in mechanical properties. The market trend for zirconia is the production of CAD/CAM disks containing more fracture resistant 3Y-TZP at the bottom layers and more translucent 5Y-PSZ at the top. Although flaws located between layers in multilayered blocks might represent a problem, newer generations of zirconia layered blocks appear to have solved this problem with novel powder compaction technology. Significant advancements in zirconia processing technologies have been made, but there is still plenty of room for improvement, especially in the fields of high-speed sintering and additive manufacturing. SIGNIFICANCE The wide range of zirconia materials currently available in the market may cause confusion in materials selection. It is therefore imperative for dental clinicians and laboratory technicians to get the needed knowledge on zirconia material science, to follow manufacturers' instructions, and to optimize the design of the prosthetic restoration with a good understanding where to reinforce the structure with a tough and strong zirconia.
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Affiliation(s)
- Paulo Francisco Cesar
- Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
| | | | - Karina Felix Santos
- Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil
| | - Susanne S Scherrer
- Division of Fixed Prosthodontics and Biomaterials, University Clinics of Dental Medicine, University of Geneva, Geneva, Switzerland
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, USA
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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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Gali S, Gururaja S, Patel Z. Methodological approaches in graded dental ceramics. Dent Mater 2024; 40:e1-e13. [PMID: 38438282 PMCID: PMC7615955 DOI: 10.1016/j.dental.2024.02.016] [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: 10/14/2023] [Revised: 01/05/2024] [Accepted: 02/12/2024] [Indexed: 03/06/2024]
Abstract
BACKGROUND Functionally graded materials (FGM) with indistinct boundaries potentially eliminate the damaging stresses occurring at the interfaces. FGM applications in dental ceramics have enhanced their fatigue resistance and interfacial toughness. OBJECTIVES This scoping review aims to map graded designs in dental ceramics, distinguish their methodological approaches with their material characteristics and properties, and understand the factors affecting the outcomes of each of the graded approaches. METHODS A systematic electronic search was performed with the databases MEDLINE (PubMed), Scopus, Cochrane Library, EBSCO, and Google Scholar along with a manual search. RESULTS About 2675 articles were initially found from all the searches with no date restriction till July 2023. After rejecting duplicates and based on exclusion criteria, about 52 articles were included. SIGNIFICANCE Methodological approaches in grading such as glass-infiltration and silica-infiltration have been investigated on pre-sintered zirconia. The type of infiltration and the method of infiltrate application significantly influenced the phase transformation of zirconia, its microstructure, surface hardness, fracture toughness, flexural strength, wear, and fatigue strength of graded dental zirconia. Interlayers were accommodated between metal-ceramic and veneer-core all-ceramic layers. Fractions of zirconia-porcelain and alumina-porcelain showed high bending strength and better stress distribution. The results of finite element analysis studies predicted that using 10-layered graded layers reduced the stresses at the crown-cement-dentin interface.
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Affiliation(s)
- Sivaranjani Gali
- Dept. of Prosthodontics, Faculty of Dental Sciences, M.S.Ramaiah University of Applied Sciences, Bangalore 560054, India.
| | | | - Zulekha Patel
- Dept. of Prosthodontics, Faculty of Dental Sciences, M.S.Ramaiah University of Applied Sciences, Bangalore 560054, India
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Espinar C, Pérez MM, Pulgar R, Leon-Cecilla A, López-López MT, Della Bona A. Influence of printing orientation on mechanical properties of aged 3D-printed restorative resins. Dent Mater 2024; 40:756-763. [PMID: 38429216 DOI: 10.1016/j.dental.2024.02.023] [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: 07/19/2023] [Revised: 02/15/2024] [Accepted: 02/18/2024] [Indexed: 03/03/2024]
Abstract
OBJECTIVE To evaluate the influence of printing orientation on flexural strength (σf) and elastic modulus (E) of different 3D printing dental restorative resins. METHODS Bar-shaped specimens (n = 20) were fabricated from two SLA-printed resins (FT- Formlabs Temporary, and FP- Formlabs Permanent) and two DLP-printed resins (DFT- Detax Freeprint Temp, and GCT- GC Temporary) using two building orientations (0º and 90º). The 3D-printed structures were aged (14 d) before submitted to three-point bending in 37ºC distilled water at a crosshead speed of 1.0 ± 0.3 mm/min until fracture to calculate the σf and the E values. The fractured surfaces were evaluated using stereomicroscopy and scanning electron microscopy (SEM) following fractography principles. Data were statistically analyzed using two-way ANOVA and Tukey post-hoc (α = 0.001). RESULTS FP and FT showed significantly higher E values than DFT and GCT, irrespectively of printing orientation (p < 0.001). There was no statistical difference between the building orientations (0º and 90º) for the mean σf and E values for the resin materials evaluated. Fractographic characteristics were similar for the surface fracture from all the materials evaluated, showing typical brittle fracture behavior. SIGNIFICANCE Printing orientation did not influence of flexural strength and elastic modulus values for the 3D-printed resin structures evaluated. Surface topography was mostly governed by the 3D printer type.
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Affiliation(s)
- Cristina Espinar
- Department of Stomatology, Faculty of Dentistry, Colegio Máximo, Campus de Cartuja s/n. University of Granada, 18071 Granada, Spain
| | - María M Pérez
- Department of Optics, Faculty of Science, Campus Fuentenueva, Edificio Mecenas, s/n. University of Granada, 18071 Granada, Spain
| | - Rosa Pulgar
- Department of Stomatology, Faculty of Dentistry, Colegio Máximo, Campus de Cartuja s/n. University of Granada, 18071 Granada, Spain
| | - Alberto Leon-Cecilla
- Department of Applied physics, Faculty of Science, Campus Fuentenueva, University of Granada, 18071 Granada, Spain
| | - Modesto T López-López
- Department of Applied physics, Faculty of Science, Campus Fuentenueva, University of Granada, 18071 Granada, Spain
| | - Alvaro Della Bona
- Postgraduate Program in Dentistry, Dental School, University of Passo Fundo, Campus I, Passo Fundo, RS, Brazil.
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9
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Duran Ojeda G, Gresnigt MMM, Romero V, Sanhueza V, Wendler M. Clinical report and fractographic analysis of a fractured partial laminate veneer. J Prosthet Dent 2024; 131:543-547. [PMID: 36372585 DOI: 10.1016/j.prosdent.2022.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/04/2022] [Accepted: 10/04/2022] [Indexed: 11/12/2022]
Abstract
Ceramic partial laminate veneers represent a conservative option for the correction of morphological abnormalities, diastemas, and fractured anterior teeth, with minimal or no tooth preparation. The present clinical report describes the use of a partial laminate veneer to correct the shape of a maxillary right central incisor to match the restoration of the more damaged adjacent tooth. The failure of the partial laminate veneer after only 18 months was analyzed using a systematic fractographic approach, identifying critical considerations that should be addressed when providing this type of restoration.
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Affiliation(s)
- Gerardo Duran Ojeda
- PhD student, Department of Restorative Dentistry and Biomaterials, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, University of Groningen, Groningen, The Netherlands; Professor, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Iquique, Chile
| | - Marco M M Gresnigt
- Head of the Department, Department of Restorative Dentistry and Biomaterials, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, University of Groningen, Groningen, The Netherlands; Dentist, Department of Special Dental Care, Martini Hospital, Groningen, The Netherlands
| | - Victor Romero
- Owner and Manager, Dental Laboratory DentScire, Santiago, Chile
| | - Vilma Sanhueza
- Associate Professor, Instituto de Geología Económica Aplicada (GEA), Universidad de Concepción, Concepción, Chile
| | - Michael Wendler
- Associate Professor, Department of Restorative Dentistry, Faculty of Dentistry, Universidad de Concepcion, Concepcion, Chile.
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Kwon YS, Kim JH, Lee H, Scherrer SS, Lee HH. Strength-limiting damage and defects of dental CAD/CAM full-contour zirconia ceramics. Dent Mater 2024; 40:653-663. [PMID: 38378372 DOI: 10.1016/j.dental.2024.02.003] [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: 10/02/2023] [Revised: 01/03/2024] [Accepted: 02/06/2024] [Indexed: 02/22/2024]
Abstract
OBJECTIVE This study aimed to compare the four-point flexural strength of CAM-milled and sintered (as-sintered, AS) specimens with those of high-polished (HP) specimens using chairside polishing systems to simulate clinical surface conditions. METHODS Seven full-contour zirconia CAM/CAM blanks with various yttria contents (3, 4, 5 mol%) including three high-translucent groups (5Y) were selected to prepare flexural specimens. The bend bar specimens (2.0 × 4.0 × 25.0 mm3) were fabricated by using STL file and dental CAM machine with the respective zirconia blanks (98 mm ϕ and 10-14 mm in height). Twelve bar specimens were machined from one zirconia puck and a total of 24 specimens were prepared from each group. The pre-sintered bar specimens were sintered by using a dental zirconia furnace at 1530-1550 °C for 2 h according to the instructions. All sintered specimens were divided into two groups: as-sintered (AS) group and high-polished (HP) groups (n = 12). HP groups were subjected to polishing one surface of specimens using a three-step polishing system and finally finished with diamond polishing. After cleaning and drying, the flexural strength of all specimens was determined by a fully articulating four-point flexure fixture consisting of a 1/4-point test configuration with an inner/outer span of 10/20 mm. Statistical differences between AS and HP groups were conducted with Weibull analysis. The fractured surfaces of zirconia specimens were observed using a field emission SEM and EDS to detect failure origins. RESULTS The mean AS flexural strength values were significantly lower than those of HP counterparts. However, Weibull moduli expressing the reliability of HP groups were generally decreased although not significantly in comparison to their AS. The fracture of the AS specimens mostly originated from extrinsic CAM-milling defects, while the HP specimens were fractured from intrinsic subsurface or volume defects including pores, large grain clusters, inclusions, and corner-located critical flaws. Two high-translucent (5Y) zirconia groups were not affected in their strength and reliability after polishing, whereas one 5Y zirconia significantly increased its strength but significantly lowered its reliability. SIGNIFICANCE The extrinsic and intrinsic strength-limiting defects should be considered in evaluating the flexural strength and reliability of dental CAD/CAM zirconia ceramics for full-contour restorations. For the materials tested in this study, more optimized processing of blanks and milling protocols of pre-sintered zirconia blanks should be developed including post-sintering surface finishing to reduce the flaw population regulating strength and reliability which will affect the survivability of dental zirconia prostheses.
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Affiliation(s)
- Young-Seok Kwon
- Department of Biomaterials Science, College of Dentistry, Dankook University, 119 Dandaero, Cheonan, Chungnam 31116, Republic of Korea
| | - Jae-Heon Kim
- Department of Biomaterials Science, College of Dentistry, Dankook University, 119 Dandaero, Cheonan, Chungnam 31116, Republic of Korea
| | - Hwalim Lee
- Department of Biomaterials Science, College of Dentistry, Dankook University, 119 Dandaero, Cheonan, Chungnam 31116, Republic of Korea
| | - Susanne S Scherrer
- Division of Fixed Prosthodontics and Biomaterials, University Clinics of Dental Medicine, University of Geneva, Geneva, Switzerland.
| | - Hae-Hyoung Lee
- Department of Biomaterials Science, College of Dentistry, Dankook University, 119 Dandaero, Cheonan, Chungnam 31116, Republic of Korea; Institute of Tissue Regeneration Engineering, Dankook University, 119 Dandaero, Cheonan, Chungnam 31116, Republic of Korea.
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11
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Li Q, Yang Y, Chen K, Jiang Y, Swain MV, Yao M, He Y, Liang Y, Jian Y, Zhao K. Effect of low-temperature degradation on the fatigue performance of dental strength-gradient multilayered zirconia restorations. J Dent 2024; 142:104866. [PMID: 38281620 DOI: 10.1016/j.jdent.2024.104866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 01/16/2024] [Accepted: 01/25/2024] [Indexed: 01/30/2024] Open
Abstract
OBJECTIVES Fatigue and low-temperature degradation (LTD) are the main factors contributing to zirconia restoration failure. This study evaluated the effect of LTD on the fatigue performance of the novel "strength & shade-gradient" multilayered zirconia restorations. METHODS Discs (15 mm × 1.2 mm) of each yttria content layer from a newly developed strength-gradient multilayered zirconia were fabricated and under accelerated aging in an autoclave at 134℃ for 0 h, 32 h, and 64 h. Then, the phase transformation, microstructure, and mechanical properties after LTD were assessed. In addition, the crown samples, including the multi-Zir, 3Y-Zir, and 5Y-Zir were fabricated, and their monotonic and fatigue load before and after LTD, percentage of fatigue degradation (Sd) and the fracture morphology were investigated. Statistical analyses were performed using paired samples t-test (α' = α/3 = 0.017), one-way ANOVA and Weibull analysis. RESULTS After LTD, the phase transformation, surface roughness, depth of transformed zone, and residual stress were increased and inversely associated with the yttria content. The indentation elastic modulus and hardness after LTD decreased; however, there was no significant difference between the different yttria content layers. The monotonic and fatigue load of multi-Zir restorations decreased, but their Weibull modulus increased, and Sd decreased, similar to 3Y-Zir. The crack origin was associated with the cervical region. CONCLUSION These results show that although LTD reduces the absolute fatigue strength of strength-gradient multilayered zirconia restorations, it also reduces the effect of cyclic fatigue itself on the strength of zirconia (relative to monotonic strength), which might be due to the increase of residual stress. CLINICAL SIGNIFICANCE The novel "strength & shade-gradient" multilayered zirconia restorations show a promising performance during in vitro LTD and fatigue test and their reliability to some extent is comparable to 3Y-Zir. Yet, further in vivo longitudinal studies are warranted to confirm their precise performance.
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Affiliation(s)
- Qiulan Li
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yunxu Yang
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Kuangyao Chen
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yingyu Jiang
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Michael V Swain
- Don State Technical University, Rostov-on-Don 344000, Russia; AMME, Sydney University, Sydney, Australia
| | - Mianfeng Yao
- Xiangya Hospital Central South University, Changsha 410008, China
| | - Ying He
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yujie Liang
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
| | - Yutao Jian
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China; Institute of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China.
| | - Ke Zhao
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
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12
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Dalla-Nora F, Da Rosa LS, Pereira GKR, Valandro LF, Rippe MP. Is dentin analogue material a viable substitute for human dentin in fatigue behavior studies? J Mech Behav Biomed Mater 2024; 150:106312. [PMID: 38134583 DOI: 10.1016/j.jmbbm.2023.106312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/04/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023]
Abstract
This study aimed to compare the fatigue performance of a lithium disilicate ceramic cemented on different substrates (human dentin and glass fiber-reinforced epoxy resin - GFRER), treated with different types of conditioning (CTR - without surface conditioning; HF5 - 5% hydrofluoric acid; HF10 - 10% hydrofluoric acid; H3PO4 - phosphoric acid 37%; SAND - sandblasting with aluminum oxide). The occlusal surface of human molars (DENT group) (n = 15) was ground for dentin exposure and the root portion was cut, then the dentin slice (2.0 mm thick) was conditioned with 37% phosphoric acid and a dual-curing dental adhesive was applied. The GFRER in a round-rod format was cut into discs (Ø = 10 mm, 2.0 mm thick). Lithium disilicate glass ceramic blocks (IPS e.max CAD, Ivoclar, Schaan, Liechtenstein) were shaped into a cylinder format and cut, resulting in 90 discs (Ø = 10 mm, 1.5 mm thick). The substrate materials of each group were etched according to the groups and the ceramic was etched with 5% hydrofluoric acid for 30 s. A silane coupling agent was applied over the cementation surface in ceramic and GFRER surfaces and a dual cement was used for cementation (ceramic/GFRER or dentin). The disc/disc sets were submitted to thermocycling (25,000 cycles + storage for 6 months), and then tested in step-wise accelerated cyclic fatigue test. The failure pattern and topography were analyzed and the roughness and contact angle were measured before and after surface treatment. The DENT group presented the lowest load to failure values and number of cycles to failure in fatigue (637.33 N; 118.333), showing no statistical similarity with any of the other tested groups (p < 0.05). The topographic analysis showed that all proposed surface treatments modified the substrate surface when compared to the CTR group. All of the fractographical inspections demonstrated failure by radial crack. Considering the roughness analysis, the post-etched DENT group showed similar roughness to all groups of GFRER materials with their surface treated, except for SAND, which showed greater roughness and statistically different from the other groups. The DENT group (49.5) showed statistically different post-conditioning contact angle values from the HF10 group (96.5) and similar to the other groups. The glass fiber-reinforced epoxy resin was not able to simulate the results presented by the human dentin substrate when cemented to lithium disilicate regarding fatigue failure load and number of cycles for failure, regardless of the surface treatment. Lithium disilicate cemented on dentin analogue overestimates the load values for fatigue failure.
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Affiliation(s)
- F Dalla-Nora
- MSciD and PhD Post-Graduate Program in Oral Science [Prosthodontics Units], Faculty of Dentistry, Federal University of Santa Maria [UFSM], Avenue Roraima 1000, Building 26F, room 2383, Zip Code: 97105-900, Santa Maria, Rio Grande do Sul State, Brazil.
| | - L S Da Rosa
- MSciD and PhD Post-Graduate Program in Oral Science [Prosthodontics Units], Faculty of Dentistry, Federal University of Santa Maria [UFSM], Avenue Roraima 1000, Building 26F, room 2383, Zip Code: 97105-900, Santa Maria, Rio Grande do Sul State, Brazil.
| | - G K R Pereira
- MSciD and PhD Post-Graduate Program in Oral Science [Prosthodontics Units], Faculty of Dentistry, Federal University of Santa Maria [UFSM], Avenue Roraima 1000, Building 26F, room 2383, Zip Code: 97105-900, Santa Maria, Rio Grande do Sul State, Brazil.
| | - L F Valandro
- MSciD and PhD Post-Graduate Program in Oral Science [Prosthodontics Units], Faculty of Dentistry, Federal University of Santa Maria [UFSM], Avenue Roraima 1000, Building 26F, room 2383, Zip Code: 97105-900, Santa Maria, Rio Grande do Sul State, Brazil.
| | - M P Rippe
- MSciD and PhD Post-Graduate Program in Oral Science [Prosthodontics Units], Faculty of Dentistry, Federal University of Santa Maria [UFSM], Avenue Roraima 1000, Building 26F, room 2383, Zip Code: 97105-900, Santa Maria, Rio Grande do Sul State, Brazil.
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13
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Prause E, Malgaj T, Kocjan A, Beuer F, Hey J, Jevnikar P, Schmidt F. Mechanical properties of 3D-printed and milled composite resins for definitive restorations: An in vitro comparison of initial strength and fatigue behavior. J ESTHET RESTOR DENT 2024; 36:391-401. [PMID: 37680013 DOI: 10.1111/jerd.13132] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 08/06/2023] [Accepted: 08/25/2023] [Indexed: 09/09/2023]
Abstract
OBJECTIVE To evaluate the flexural strength and fatigue behavior of a novel 3D-printed composite resin for definitive restorations. MATERIALS AND METHODS Fifty disc-shaped specimens were manufactured from each of a nanohybrid composite resin (NHC), polymer-infiltrated ceramic network (PICN), and 3D-printed composite resin (3D) with CAD-CAM technology. Biaxial flexural strength (σin ) (n = 30 per group) and biaxial flexural fatigue strength (σff ) (n = 20 per group) were measured using piston-on-three-balls method, employing a staircase approach of 105 cycles. Weibull statistics, relative-strength degradation calculations, and fractography were performed. The results were analyzed with 1-way ANOVA and Games-Howell post hoc test (α = 0.05). RESULTS Significant differences in σin and σff among the groups (p < 0.001) were detected. The NHC group provided the highest mean ± standard deviation σin and σff (237.3 ± 31.6 MPa and 141.3 ± 3.8 MPa), followed by the PICN (140.3 ± 12.9 MPa and 73.5 ± 9.9 MPa) and the 3D (83.6 ± 18.5 MPa and 37.4 ± 23.8 MPa) groups. The 3D group exhibited significantly lower Weibull modulus (m = 4.7) and up to 15% higher relative strength degradation with areas of nonhomogeneous microstructure as possible fracture origins. CONCLUSIONS The 3D-printed composite resin exhibited the lowest mechanical properties, where areas of nonhomogeneous microstructure developed during the mixing procedure served as potential fracture origins. CLINICAL SIGNIFICANCE The clinical indications of the investigated novel 3D-printed composite resin should be limited to long-term provisional restorations. A cautious procedure for mixing the components is crucial before the 3D-printing process, since nonhomogeneous areas developed during the mixing could act as fracture origins.
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Affiliation(s)
- Elisabeth Prause
- Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Tine Malgaj
- Department of Prosthodontics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Andraž Kocjan
- Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Florian Beuer
- Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Jeremias Hey
- Department of Prosthodontics, School of Dental Medicine, Martin-Luther-University, Halle, Germany
| | - Peter Jevnikar
- Department of Prosthodontics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Franziska Schmidt
- Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Berlin, Germany
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Saratti CM, Scotti N, Comba A, Bijelic-Donova J, Suchy T, Abdelaziz M, Leprince JG, Rocca GT. Exploring the influence of placing bi-directional E-glass fibers as protective layer under a CAD-CAM resin composite on the fracture pattern. Dent Mater 2023; 39:986-993. [PMID: 37734973 DOI: 10.1016/j.dental.2023.09.003] [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: 10/31/2022] [Revised: 08/17/2023] [Accepted: 09/15/2023] [Indexed: 09/23/2023]
Abstract
OBJECTIVES To investigate the influence of the presence and position of bidirectional E-glass fibers under a CAD-CAM resin composite on the fracture pattern evaluated both after quasi-static mechanical loading and after fatigue. METHODS Rectangular specimens (10 mm-long, 5 mm-large and 4.2 mm-thick) were prepared and divided into four groups (n = 30/group). The control group (C-Group) consisted of a 4.2 mm-thick layer of monolithic CAD/CAM resin composite resin (Cerasmart, GC). In the 3 other groups including the placement of a fiber layer (F-Groups), the CAD/CAM resin composite layer was reduced to 3-, 2- and 1-mm thickness (F3-, F2- and F1-Groups, respectively). Two bonded layers of bidirectional E-glass FRC (Dentapreg, ADM A.S.) were bonded underneath and a light-curable resin composite base (Gaenial Posterior, GC) was then added to reach a total thickness of 4.2 mm for all samples. In each group, half of the specimens (n = 15) were submitted to quasi-static mechanical loading to failure in a universal testing machine. The other half (n = 15) was subjected to cyclic isometric stepwise loading until failure or completion of 105000 cycles (5000 cycles at 500 N, followed by five stages of 20000 cycles at 750 N, 1000 N, 1250 N, 1500 N, and 1750 N). The data were analyzed by Weibull statistics for quasi-static loading, and by the Kaplan-Meier product limit estimation procedure after fatigue. All fractured specimens were studied using light and electron microscopy techniques, and the types of fracture were determined. RESULTS For quasi-static mechanical loading, significant differences were observed for Weibull modulus and characteristic strength between groups, with values ranging from 10.8 to 22.4 for the former and from 2336.6 to 2974.7 for the latter. Also, survival after stepwise fatigue revealed statistically significant differences between groups (p < 0.05), the lowest values of cycles before failure being observed for F1-Group - Median = 61223 (50415; 65446) - as compared to the other groups - C-Group: Median = 89005 (86189; 98195); F3-Group: Median = 85198 (77279; 87860); F2-Group: Median = 89306 (87454; 97024). Both in quasi-static loading and after fatigue, the observation of fracture modes revealed major differences. While all fractures were vertical (split) in C-Group, the majority of the specimens in F-Groups presented some degree of horizontal deflection of the crack. In all deviated fractures, fractographic analysis confirmed a toughening effect of the fiber layer. SIGNIFICANCE The present in vitro work tends to show that the fracture pattern of CAD-CAM resin composites is favorably affected by the presence and position of an underlying bidirectional E-glass fiber layer. The placement of E-glass fibers under a CAD-CAM resin composite may therefore represent an interesting strategy to reduce the risk of catastrophic restoration failure, which could be integrated in the development of the new generation of indirect materials, possibly in 3D-printing approaches.
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Affiliation(s)
- C M Saratti
- Division of Cariology and Endodontology, School of Dentistry, University of Geneva, Geneva, Switzerland.
| | - N Scotti
- Department of Surgical Sciences, Dental School, University of Turin, Turin, Italy
| | - A Comba
- Department of Surgical Sciences, Dental School, University of Turin, Turin, Italy
| | - J Bijelic-Donova
- Department of Prosthetic Dentistry and Stomatognathic Physiology, Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, Turku, Finland
| | - T Suchy
- Department of Composites and Carbon Materials, Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - M Abdelaziz
- Division of Cariology and Endodontology, School of Dentistry, University of Geneva, Geneva, Switzerland
| | - J G Leprince
- Division of Cariology and Endodontology, School of Dentistry, University of Geneva, Geneva, Switzerland
| | - G T Rocca
- Division of Cariology and Endodontology, School of Dentistry, University of Geneva, Geneva, Switzerland
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15
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Ghelbere R, Ilie N. Validation of the Orr theory in dental resin-based composites: A fractographic approach. J Mech Behav Biomed Mater 2023; 144:105982. [PMID: 37352623 DOI: 10.1016/j.jmbbm.2023.105982] [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: 04/26/2023] [Revised: 06/14/2023] [Accepted: 06/17/2023] [Indexed: 06/25/2023]
Abstract
OBJECTIVES The present study aimed to assess the applicability of Orr's equation on light-cured resin-based composites (RBCs) tested in 3- and 4-point bending tests, as well as assess the operator reliability of this method. METHODS Fracture mirrors of 320 specimens (n = 320) made of four RBCs that had failed in the two tests were analyzed microscopically and consequently two radii of each specimen were measured by two operators, each measuring twice. The mirror constant A was calculated using Orr's equation. The results of the two operators were compared using a t-Test and further assessment of the data was performed using a MANOVA, Tukey's post hoc test and regression analysis. RESULTS With the exception of 11 specimens, the measurement of the fracture mirror radii was carried out successfully. The calculation of the mirror constant proved successful with a high coefficient of determination (R2 > 0.98). The calculated mirror constants were operator-independent if the results of more than one measurement was taken into consideration. The ratio of the mirror constant A to the fracture toughness KIc lay between 2.1 and 2.4 for three of the four RBC. The fourth RBC had a ratio of 1.6 and was the only one where different mirror constants were observed as a function of the testing method. SIGNIFICANCE The present study proves the applicability of brittle fracture mechanics on RBCs despite them often being regarded as not brittle due to their also plastic behavior.
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Affiliation(s)
- Raluca Ghelbere
- Department of Conservative Dentistry and Periodontology, University Hospital, LMU, Germany
| | - Nicoleta Ilie
- Department of Conservative Dentistry and Periodontology, University Hospital, LMU, Germany.
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16
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Munoz A, Zhao Z, Paolone G, Louca C, Vichi A. Flexural Strength of CAD/CAM Lithium-Based Silicate Glass-Ceramics: A Narrative Review. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4398. [PMID: 37374581 DOI: 10.3390/ma16124398] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 06/01/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023]
Abstract
Amongst chairside CAD/CAM materials, the use of lithium-based silicate glass-ceramics (LSGC) for indirect restorations has recently been increasing. Flexural strength is one of the most important parameters to consider in the clinical selection of materials. The aim of this paper is to review the flexural strength of LSGC and the methods used to measure it. METHODS The electronic search was completed within PubMed database from 2 June 2011 to 2 June 2022. English-language papers investigating the flexural strength of IPS e.max CAD, Celtra Duo, Suprinity PC, and n!ce CAD/CAM blocks were included in the search strategy. RESULTS From 211 potential articles, a total of 26 were identified for a comprehensive analysis. Categorization per material was carried out as follows: IPS e.max CAD (n = 27), Suprinity PC (n = 8), Celtra Duo (n = 6), and n!ce (n = 1). The three-point bending test (3-PBT) was used in 18 articles, followed by biaxial flexural test (BFT) in 10 articles, with one of these using the four-point bending test (4-PBT) as well. The most common specimen dimension was 14 × 4 × 1.2 mm (plates) for the 3-PBT and 12 × 1.2 mm (discs) for BFT. The flexural strength values for LSGC materials varied widely between the studies. SIGNIFICANCE As new LSGC materials are launched on the market, clinicians need to be aware of their flexural strength differences, which could influence the clinical performance of restorations.
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Affiliation(s)
- Alvaro Munoz
- Faculty of Dentistry, University of Chile, Santiago 8380544, Chile
| | - Zejiao Zhao
- Dental Academy, University of Portsmouth, Portsmouth PO1 2QG, UK
| | - Gaetano Paolone
- Dental School, IRCCS San Raffaele Hospital, Vita-Salute University, 20132 Milan, Italy
| | - Chris Louca
- Dental Academy, University of Portsmouth, Portsmouth PO1 2QG, UK
| | - Alessandro Vichi
- Dental Academy, University of Portsmouth, Portsmouth PO1 2QG, UK
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17
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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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Alshamrani A, Alhotan A, Owais A, Ellakwa A. The Clinical Potential of 3D-Printed Crowns Reinforced with Zirconia and Glass Silica Microfillers. J Funct Biomater 2023; 14:jfb14050267. [PMID: 37233377 DOI: 10.3390/jfb14050267] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/09/2023] [Accepted: 05/09/2023] [Indexed: 05/27/2023] Open
Abstract
The development of 3D-printed crown resin materials with improved mechanical and physical properties is an area of growing interest in dentistry. This study aimed to develop a 3D-printed crown resin material modified with zirconia glass (ZG) and glass silica (GS) microfillers to enhance overall mechanical and physical properties. A total of 125 specimens were created and divided into five groups: control unmodified resin, 5% either ZG or GS reinforced 3D-printed resin, and 10% either ZG or GS reinforced 3D-printed resin. The fracture resistance, surface roughness, and translucency parameter were measured, and fractured crowns were studied under a scanning electron microscope. The results showed that 3D-printed parts that were strengthened with ZG and GS microfillers demonstrated comparable mechanical performance to unmodified crown resin but resulted in greater surface roughness, and only the group that contained 5% ZG showed an increase in translucency. However, it should be noted that increased surface roughness may impact the aesthetics of the crowns, and further optimisation of microfillers concentrations may be necessary. These findings suggest that the newly developed dental-based resins that incorporate microfillers could be suitable for clinical applications, but further studies are necessary to optimise the nanoparticle concentrations and investigate their long-term clinical outcomes.
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Affiliation(s)
- Abdullah Alshamrani
- Oral Rehabilitation & Dental Biomaterial and Bioengineering, The University of Sydney, Sydney, NSW 2006, Australia
- Department of Dental Health, College of Applied Medical Sciences, King Saud University, Riyadh P.O. Box 12372, Saudi Arabia
| | - Abdulaziz Alhotan
- Department of Dental Health, College of Applied Medical Sciences, King Saud University, Riyadh P.O. Box 12372, Saudi Arabia
| | - Ahmed Owais
- The X-ray Spectroscopy Node, Sydney Analytical, Core Research Facilities, The University of Sydney, Sydney, NSW 2006, Australia
| | - Ayman Ellakwa
- Oral Rehabilitation & Dental Biomaterial and Bioengineering, The University of Sydney, Sydney, NSW 2006, Australia
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Marini G, Saldanha da Rosa L, Machado PS, Silvestre FA, Valandro LF, Feitosa VP, Pereira GKR, Bacchi A. Fatigue performance analysis of strength-graded zirconia polycrystals for monolithic three-unit implant-supported prostheses. J Mech Behav Biomed Mater 2023; 140:105736. [PMID: 36801783 DOI: 10.1016/j.jmbbm.2023.105736] [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: 11/05/2022] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/16/2023]
Abstract
The aim of this study was to evaluate the fatigue behavior of strength-graded zirconia polycrystals used as monolithic three-unit implant-supported prosthesis; complementarily, crystalline phase and micromorphology were also assessed. Fixed prostheses with 3 elements supported by 2 implants were confectioned, as follows: Group 3Y/5Y - monolithic structures of a graded 3Y-TZP/5Y-TZP zirconia (IPS e.max® ZirCAD PRIME); Group 4Y/5Y - monolithic structures of a graded 4Y-TZP/5Y-TZP zirconia (IPS e.max® ZirCAD MT Multi); Group Bilayer - framework of a 3Y-TZP zirconia (Zenostar T) veneered with porcelain (IPS e.max Ceram). The samples were tested for fatigue performance with step-stress analysis. The fatigue failure load (FFL), the number of cycles required until failure (CFF), and the survival rates in each cycle were recorded. The Weibull module was calculated and the fractography analyzed. The crystalline structural content via Micro-Raman spectroscopy and the crystalline grain size via Scanning Electron microscopy were also assessed for graded structures. Group 3Y/5Y showed the highest FFL, CFF, probability of survival, and reliability (based on Weibull modulus). Group 4Y/5Y showed significantly superior FFL and probability of survival than group bilayer. Fractographic analysis revealed catastrophic flaws in the monolithic structure and cohesive fracture of porcelain in bilayer prostheses, all originating from the occlusal contact point. The graded zirconia presented small grain size (≤0.61 μm), with the smallest values at the cervical region. The main composition of graded zirconia was of grains at tetragonal phase. The strength-graded monolithic zirconia, especially the 3Y-TZP/5Y-TZP, showed to be promising for use as monolithic three-unit implant-supported prosthesis.
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Affiliation(s)
- Gabriel Marini
- Post-Graduate Program in Dentistry, Atitus Education, Passo Fundo, RS, Brazil
| | - Lucas Saldanha da Rosa
- Post-Graduate Program in Dental Sciences, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Pablo Soares Machado
- Post-Graduate Program in Dental Sciences, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil
| | | | - Luiz Felipe Valandro
- Post-Graduate Program in Dental Sciences, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Victor Pinheiro Feitosa
- Post-Graduate Program in Dentistry, Paulo Picanço School of Dentistry (FACPP), Fortaleza, CE, Brazil
| | | | - Atais Bacchi
- Post-Graduate Program in Dentistry, Paulo Picanço School of Dentistry (FACPP), Fortaleza, CE, Brazil.
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Zhai Z, Qian C, Jiao T, Sun J. In vitro fracture and fatigue resistance of monolithic zirconia crowns fabricated by stereolithography. J Prosthet Dent 2023:S0022-3913(23)00127-0. [PMID: 36966099 DOI: 10.1016/j.prosdent.2023.02.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 02/22/2023] [Accepted: 02/22/2023] [Indexed: 03/27/2023]
Abstract
STATEMENT OF PROBLEM Stereolithography has been used to print zirconia ceramic crowns with acceptable dimensional accuracy and fracture force. However, studies that compared the fatigue resistance of zirconia crowns fabricated by stereolithography are lacking. PURPOSE The purpose of this in vitro study was to compare the fracture and fatigue resistance of monolithic zirconia crowns printed by stereolithography apparatus (SLA) and digital light processing (DLP) with those of zirconia crowns milled by computer numerical control (CNC). MATERIAL AND METHODS A total of 120 crowns were fabricated (n=40/material) and underwent 0, 104, 105, or 106 dynamic loading cycles of 30 to 300 N in artificial saliva, followed by a static fracture loading test (n=10). After fracture, 1 crown from each group was selected for fractography analysis by scanning electron microscopy (SEM). Data were statistically analyzed through 2-way ANOVA and post hoc analysis for multiple comparisons (α=.05). RESULTS The 2-way ANOVA results showed that the mean ±standard deviation force at fracture was the highest for CNC (before fatigue loading: 5154 ±568 N, 104: 5735 ±1231 N, 105: 5523 ±797 N, and 106: 6007 ±1258 N), followed by DLP (before fatigue loading: 3381 ±612 N, 104: 4046 ±1146 N, 105: 2929 ±559 N, and 106: 3223 ±739 N), and the lowest for SLA (before fatigue loading: 2956 ±598 N, 104: 2757 ±421 N, 105: 3326 ±391 N, and 106: 3103 ±246 N) (P<.01). The fracture force of the crowns was not significantly affected by the number of fatigue cycles (P>.05). Fractography analysis showed that the number of arrest lines increased for crowns of all 3 materials. SEM images also showed the steps of SLA and DLP from their layer-by-layer printing and small cracks between layers of SLA after 106 loading cycles. CONCLUSIONS The fracture force of monolithic zirconia crowns milled by CNC was significantly higher than that of zirconia crowns printed by stereolithography. Zirconia crowns printed by SLA and DLP could withstand typical clinical conditions, and their fracture and fatigue resistance exceeded the clinically estimated average occlusal forces.
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Affiliation(s)
- Zidi Zhai
- Graduate student, Department of Prosthodontics, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; and Shanghai Research Institute of Stomatology, Shanghai, PR China
| | - Chao Qian
- Senior Lecturer, Department of Prosthodontics, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; and Shanghai Research Institute of Stomatology, Shanghai, PR China
| | - Ting Jiao
- Professor, Department of Prosthodontics, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; and Shanghai Research Institute of Stomatology, Shanghai, PR China
| | - Jian Sun
- Professor, Department of Prosthodontics, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; and Shanghai Research Institute of Stomatology, Shanghai, PR China.
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21
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Gao Y, Ding Q, Li W, Gu R, Zhang P, Zhang L. Role and Mechanism of a Micro-/Nano-Structured Porous Zirconia Surface in Regulating the Biological Behavior of Bone Marrow Mesenchymal Stem Cells. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 36913521 DOI: 10.1021/acsami.2c22736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Zirconia as a promising dental implant material has attracted much attention in recent years. Improving the bone binding ability of zirconia is critical for clinical applications. Here, we established a distinct micro-/nano-structured porous zirconia through dry-pressing with addition of pore-forming agents followed by hydrofluoric acid etching (POROHF). Porous zirconia without hydrofluoric acid treatment (PORO), sandblasting plus acid-etching zirconia, and sintering zirconia surface were applied as controls. After human bone marrow mesenchymal stem cells (hBMSCs) were seeded on these four groups of zirconia specimens, we observed the highest cell affinity and extension on POROHF. In addition, the POROHF surface displayed an improved osteogenic phenotype in contrast to the other groups. Moreover, the POROHF surface facilitated angiogenesis of hBMSCs, as confirmed by optimal stimulation of vascular endothelial growth factor B and angiopoietin 1 (ANGPT1) expression. Most importantly, the POROHF group demonstrated the most obvious bone matrix development in vivo. To investigate further the underlying mechanism, RNA sequencing was employed and critical target genes modulated by POROHF were identified. Taken together, this study established an innovative micro-/nano-structured porous zirconia surface that significantly promoted osteogenesis and investigated the potential underlying mechanism. Our present work will improve the osseointegration of zirconia implants and help further clinical applications.
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Affiliation(s)
- Yuan Gao
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing 100081, PR China
| | - Qian Ding
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing 100081, PR China
| | - Wenjin Li
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing 100081, PR China
| | - Ranli Gu
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing 100081, PR China
| | - Ping Zhang
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing 100081, PR China
| | - Lei Zhang
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing 100081, PR China
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22
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Influence of thermo-mechanical aging on fracture resistance and wear of digitally standardized chairside computer-aided-designed/computer-assisted-manufactured restorations. J Dent 2023; 130:104450. [PMID: 36773741 DOI: 10.1016/j.jdent.2023.104450] [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: 07/03/2022] [Revised: 01/24/2023] [Accepted: 02/08/2023] [Indexed: 02/11/2023] Open
Abstract
OBJECTIVES To investigate the influence of thermal cycling and mechanical loading (TCML) aging on fracture resistance and wear behavior of various chairside computer-aided-designed/computer-assisted-manufactured (CAD/CAM) premolar crowns cemented on standardized tooth abutments. METHODS Eighty chairside CAD/CAM crowns were prepared using lithium disilicate (IPS e.max CAD; EM), zirconia-infiltrated lithium silicate (Celtra Duo; CD), polymer-infiltrated ceramic network (Vita Enamic; VE), and resin nanoceramics (Cerasmart; CS) (n = 20). The specimens were divided into two groups (n = 10). In one group, they were subjected to TCML: thermocycling (6000 cycles in distilled water at 5-55 °C) and mechanical loading (50 N for 1.2 × 106 cycles), while in control group they were stored in distilled water (37 °C for 24 h). The fracture load, height loss, and volume wear of the crowns were measured after TCML. Fractography was performed on fractured specimens. Data were analyzed using analysis of variance and multiple comparison tests (α=0.05). RESULTS The mean fracture loads of EM and CD were significantly higher than those of EC and CS (p<0.05). There was no significant change in the fracture load of any CAD/CAM crowns after TCML (p>0.05). CS exhibited a significantly higher volume wear than the other materials investigated. The wear tracts of all TCML crowns acted as failure origins during the fracture test. CONCLUSIONS The fracture resistance of glass-ceramic CAD/CAM crowns was significantly higher than that of resin composite crowns. A 5-year TCML aging did not affect the fracture resistance of CAD/CAM crowns investigated. However, TCML treatment produces a larger wear track in CS than in other materials. CLINICAL SIGNIFICANCE Appropriate chairside CAD/CAM restorative material should be selected for successful clinical practice after considering the fracture and wear resistance of the crowns.
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23
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Alghazzawi TF, Janowski GM, Ning H, Eberhardt AW. Qualitative SEM analysis of fracture surfaces for dental ceramics and polymers broken by flexural strength testing and crown compression. J Prosthodont 2023. [PMID: 36739572 DOI: 10.1111/jopr.13659] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 01/22/2023] [Indexed: 02/06/2023] Open
Abstract
PURPOSE To perform qualitative analysis using scanning electron microscopy (SEM) of fracture surfaces for ceramic and polymeric dental materials broken via standardized flexural and crunch-the-crown (CTC) tests. MATERIALS AND METHODS Zirconia, glass-ceramic, and polymeric (Trilor; TRI, Juvora; JUV, Pekkton; PEK) materials were loaded using crowns for CTC tests, discs (zirconia and glass-ceramics) for piston-on-3 ball tests, bars (polymer) for 3-point bend tests, and bars (zirconia, glass-ceramics) for 4-point bend tests. SEM was used to characterize the fracture surfaces and identify fracture surface features (e.g., origin, mist, hackle, and the direction of crack propagation [DCP]). Electron dispersive spectroscopy was used to identify the local chemistry. RESULTS Fracture surface features were found to be less visually apparent for glass-ceramics than zirconia. For zirconia bars, fractures originated roughly midway between the corner and center for processing defects related to sintering. Fractures originated at the bottom corners of glass-ceramic bars (void or surface flaw) and PEK bars (surface flaw). TRI bar failures exposed glassy fibers. Fracture features were generally less discernable for discs compared to bars for zirconia and glass-ceramics. Ceramic crowns fractured into 2 to 3 pieces, with fractures originating at the occlusal surface and clear evidence for the DCP. Failures of TRI and JUV specimens (bars and crowns) were less catastrophic than for the ceramics, with exposed fibers (TRI) and surface cracks (JUV). PEK crown and bar fractures presented dimple (ductile) features formed due to microvoid coalescence followed by brittle crack propagation. CONCLUSIONS The critical flaws responsible for failure initiation were a function of material composition and test configuration. Fractographic analysis can reveal problems associated with the manufacturing of materials, their handling, grinding and finishing/polishing procedures, the structural design and choice of material, and the quality of the final laboratory-delivered restoration.
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Affiliation(s)
- Tariq F Alghazzawi
- Department of Substitutive Dental Sciences, Taibah University, Madina, Saudi Arabia.,Department of Mechanical and Materials Engineering, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Gregg M Janowski
- Department of Mechanical and Materials Engineering, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Haibin Ning
- Department of Mechanical and Materials Engineering, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Alan W Eberhardt
- Department of Biomedical Engineering, The University of Alabama at Birmingham, Birmingham, Alabama, USA
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da Rosa LS, Velho HC, Tribst JPM, Valandro LF, Kleverlaan CJ, Pereira GKR. Weak adhesion between ceramic and resin cement impairs the load-bearing capacity under fatigue of lithium disilicate glass-ceramic crowns. J Mech Behav Biomed Mater 2023; 138:105604. [PMID: 36509013 DOI: 10.1016/j.jmbbm.2022.105604] [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: 10/27/2022] [Revised: 11/28/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022]
Abstract
OBJECTIVE To evaluate the fatigue behavior of lithium disilicate crowns with a simplified anatomy against progressive cement/ceramic debonding scenarios. MATERIALS AND METHODS Lithium disilicate crowns were fabricated via CAD/CAM and luted onto a dentin analogue material using resin cement following the manufacturer's instructions. Then, the different crown regions were isolated with paraffin oil for the absence of chemical adhesion according to four experimental groups (n = 15): Shoulder; Shoulder + Axial; Fully isolated; and Control (no insulation/fully bonded). Load to failure tests (n = 3) were run to determine cyclic fatigue parameters, and the specimens were subsequently submitted to a cyclic fatigue test (n = 12) (initial load 200 N for 5000 cycles, step 100 N, 15,000 cycles/step, frequency 20 Hz) until cracks were observed, and later fracture. The data were analyzed by Kaplan-Meier + Mantel-Cox post-hoc tests for both outcomes (cracks and fracture). Fractographic, cross-sectional surface, and finite element (FEA) analyzes were performed. RESULTS When it comes to crack occurrence when the chemical adhesion to the occlusal surface is compromised, there is worsening (p < 0.05) in fatigue behavior compared to groups where the occlusal portion of the crown is still bonded. Considering fracture occurrence, there was no difference (p > 0.05) among the tested groups. All cracks occurred in the occlusal portion, first as a radial crack at the ceramic intaglio surface, and posteriorly unleashing a Hertzian cone crack at the top surface, resulting in fractures on the frontal walls. The interface analysis showed no interference of the insulating agent. FEA showed that as the isolated areas increased, there was also an increase in both tensile and shear stresses concentration in the crown and in the cement layer. CONCLUSION The chemical adhesion between cement and ceramic is essential for better fatigue behavior of lithium disilicate crowns with a simplified anatomy, especially in the occlusal portion, but the restoration performance is impaired when such adhesion is compromised. There is an increase in crown and cement stress concentration with the progressive loss of chemical bonding of the crown's walls.
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Affiliation(s)
- Lucas Saldanha da Rosa
- MSciD and PhD Post-Graduate Program in Oral Sciences, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil.
| | - Helder Callegaro Velho
- MSciD and PhD Post-Graduate Program in Oral Sciences, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil.
| | - João Paulo Mendes Tribst
- Academic Centre for Dentistry Amsterdam (ACTA), Department of Oral Regenerative Medicine, University of Amsterdam and Vrije Universiteit Amsterdam, 1081 LA, Amsterdam, the Netherlands.
| | - Luiz Felipe Valandro
- MSciD and PhD Post-Graduate Program in Oral Sciences, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil.
| | - Cornelis Johannes Kleverlaan
- Academic Centre for Dentistry Amsterdam (ACTA), Department of Dental Material Sciences, University of Amsterdam and Vrije Universiteit Amsterdam, 1081 LA, Amsterdam, the Netherlands.
| | - Gabriel Kalil Rocha Pereira
- MSciD and PhD Post-Graduate Program in Oral Sciences, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil.
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Venturini AB, Dapieve KS, de Kok P, Pereira GKR, Valandro LF, Kleverlaan CJ. Effect of the region of the CAD/CAM block on the flexural strength and structural reliability of restorative materials. J Mech Behav Biomed Mater 2023; 138:105597. [PMID: 36459706 DOI: 10.1016/j.jmbbm.2022.105597] [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: 10/10/2022] [Revised: 11/20/2022] [Accepted: 11/22/2022] [Indexed: 11/25/2022]
Abstract
The aim of the study was to evaluate whether the region (internal or external) of the CAD/CAM block influences the mechanical performance of restorative materials. Blocks of different CAD/CAM materials (Composites: KAV - Katana Avencia; LULT - LULT Ultimate; Ceramics: ENAM - Vita Enamic; NICE - N!CE; EMP - IPS Empress CAD; VMII - Vita Mark II; EMAX - IPS e.max CAD) were selected, and direct resin composite blocks (APX - Clearfil AP-X; FSUP - Filtek Supreme) were built using the incremental technique on a mold from one of the CAD/CAM blocks. All blocks were sectioned into bar-shaped specimens (1 × 1 × 14 mm), which were separated into two groups according to the region of the block (inside or outside). 3-point bending tests were performed following ISO 6872:2015 and flexural strength data were analyzed using one-way ANOVA and Bonferroni post-hoc tests (p < 0.05). Weibull module and characteristic strength were also calculated. In general, the mean flexural strength values were not statistically different (p > 0.05) between the inside and outside regions of each material, except for LULT (inside > outside) and EMAX (outside > inside). Comparing the materials, a similar strength (only discrete variations) was observed for inside, outside or merged (inside and outside data assembled together) regions: EMAX > KAV = LULT > NICE = APX > EMP = ENAM = VMII ≥ FSUP (merged condition). Characteristic strength at 63.2% failure probability and at 5% failure probability generally corroborates such observations. There were no statistical differences for Weibull module data (inside, outside, or merged), except for KAV and NICE (outside > inside). Thus, the region from where the restoration is milled within the CAD/CAM block generally does not influence the mechanical performance hereof (flexural strength, failure probability, risk of premature failures, and mechanical reliability) of the material, except for LULT and EMAX.
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Affiliation(s)
- Andressa Borin Venturini
- Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Kiara Serafini Dapieve
- Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Paul de Kok
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, Noord-Holland, the Netherlands.
| | - Gabriel Kalil Rocha Pereira
- Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Luiz Felipe Valandro
- Faculty of Dentistry, Federal University of 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, Noord-Holland, the Netherlands.
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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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27
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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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Aboushelib MN, Elraggal A. Fractographic analysis of fractured fixation screws in implant-supported restorations. Dent Mater 2023; 39:123-131. [PMID: 36577562 DOI: 10.1016/j.dental.2022.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 11/19/2022] [Accepted: 12/14/2022] [Indexed: 12/28/2022]
Abstract
OBJECTIVES The aim of this study was to fractographically examine clinically fractured fixation screws used to fix implant supported restorations and to estimate stress at failure. METHODS 20 clinically fractured titanium implant fixation screws were collected and analyzed under scanning electron microscope in order to locate critical crack origin and calculate stress at fracture. Principles of fractographic analysis were applied using relative equations and cause and conditions of screw fracture were calculated. X-rays and patients' records were collected after approval of necessary consent forms. RESULTS Fractographic analysis revealed location and dimensions of critical crack size for every fractured screw examined. Two patterns of screw fracture were identified; the first was related to improper seating of fixation screw leading to damage at screw threads and eventual fracture of screw body. The second was related to slow crack growth propagation causing final fracture of screw body. The calculated stress at failure ranged from 755 to 804 MPa. Patients' records revealed that 75% of fractured screws were related to single unit screw retained restorations. SIGNIFICANCE Single unit screw retained restorations and improperly seated implant abutments impose high stress concentration on fixation screw which may result in fixation screw fracture.
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Affiliation(s)
- Moustafa N Aboushelib
- Dental Biomaterials Department, Faculty of Dentistry, Alexandria University, Champollion st, Azarita, Alexandria, Egypt.
| | - Alaaeldin Elraggal
- Conservative Dentistry Department, Faculty of Dentistry, Alexandria University, Champollion st, Azarita, Alexandria, Egypt.
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Mosele JC, Oliveira AR, Pizzolatto G, Benetti P, Borba M. Failure behavior of zirconia crowns subjected to air abrasion with different particle sizes. Braz Dent J 2023; 34:71-79. [PMID: 36888847 PMCID: PMC10027107 DOI: 10.1590/0103-6440202304998] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 11/17/2022] [Indexed: 03/08/2023] Open
Abstract
This study aimed to investigate the failure behavior of 3 mol.% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) prosthetic crowns air-abraded with aluminum oxide (AO) particles of different sizes. Ninety ceramic premolar crowns were produced with 3Y-TZP frameworks veneered with porcelain. Crowns were randomly divided into three groups, according to the size of the air abrasion AO particles (n = 30): (GC) untreated (control); (G53) 53 µm; (G125) 125 µm. Air abrasion was performed with 0.25 mpa pressure, 10-mm distance, for 10 s. Crowns were adhesively cemented to dentin analog abutments. Specimens were loaded in compression to failure, in 37oC distilled water, using a universal testing machine (n = 30). Fractographic analysis was performed using a stereomicroscope and SEM. The roughness of the crown's inner surface was evaluated using an optical profilometer (n = 10). Fracture load data were statistically analyzed with Weibull analysis and roughness data with Kruskal-Wallis (α = 0.05). GC had the lowest characteristic fracture load (L0), while G53 and G125 had higher and statistically similar L0 values. The Weibull modulus (m) was similar among groups. The failure modes observed were catastrophic failure and porcelain chipping. There were no differences between the roughness parameters for the experimental groups (p > 0.05). The size of the AO particles did not affect the fracture load and failure mode of 3Y-TZP crowns. Air abrasion with 53 µm and 125 µm particles resulted in a higher fracture load of ceramic crowns than the untreated group while maintaining their reliability and surface characteristics.
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Affiliation(s)
- João Cézar Mosele
- Graduate Program in Dentistry, Dental School, University of Passo Fundo(UPF), Passo Fundo, RS, Brazil
| | - Andressa Restani Oliveira
- Graduate Program in Dentistry, Dental School, University of Passo Fundo(UPF), Passo Fundo, RS, Brazil
| | - Gabriela Pizzolatto
- Graduate Program in Dentistry, Dental School, University of Passo Fundo(UPF), Passo Fundo, RS, Brazil
| | - Paula Benetti
- Graduate Program in Dentistry, Dental School, University of Passo Fundo(UPF), Passo Fundo, RS, Brazil
| | - Marcia Borba
- Graduate Program in Dentistry, Dental School, University of Passo Fundo(UPF), Passo Fundo, RS, Brazil
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Connector design effects on the in vitro fracture resistance of 3-unit monolithic prostheses produced from 4 CAD-CAM materials. J Prosthet Dent 2022; 128:1319.e1-1319.e10. [DOI: 10.1016/j.prosdent.2022.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 11/06/2022]
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Post-processing of DLP-printed denture base polymer: Impact of a protective coating on the surface characteristics, flexural properties, cytotoxicity, and microbial adhesion. Dent Mater 2022; 38:2062-2072. [DOI: 10.1016/j.dental.2022.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 10/26/2022] [Accepted: 11/11/2022] [Indexed: 11/27/2022]
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Zhang F, Monzavi M, Li M, Čokić S, Manesh A, Nowzari H, Vleugels J, Van Meerbeek B. Fracture analysis of one/two-piece clinically failed zirconia dental implants. Dent Mater 2022; 38:1633-1647. [PMID: 36064469 DOI: 10.1016/j.dental.2022.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 08/13/2022] [Accepted: 08/18/2022] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Analyzing factors that may have led to fracture of zirconia implants by macro/micro-fractography. METHODS Six one-piece and ten two-piece full-ceramic zirconia implants from two manufacturers, Z-Systems and CeraRoot, were retrieved after clinical failure. The time-to-failure ranged from 3 to 49 months. Optical and scanning electron microscopy (SEM) were used to analyze the fracture planes at the macro- and microscopic level. Treatment planning, surgical protocol, fracture-origin location and characteristic fracture features were assessed. RESULTS The fracture of all implants seemed to have been primarily due to overload in bending mode, while the fracture-initiation sites varied for the one- and two-piece implants. The fracture of all one-piece implants originated in the constriction region between two threads in the endosseous implant part. For two-piece implants, the abutment neck, internal abutment-implant connections and inner threads were found to be the main fracture-initiation sites. Surface defects at the root area for one-piece implants and damages at the abutment surface for two-piece implants were connected to the fracture origins. Importantly, the clinical failures of implants were often found to result from combined effects related to patient aspects, treatment planning/protocols, a high bending moment at the weakest link, implant-surface conditions and specific implant designs. SIGNIFICANCE This study provided information to be considered for future optimization of treatment planning and the surgical protocol for zirconia implants. Optimization of the surface conditions and the zirconia-starting powder were also suggested.
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Affiliation(s)
- Fei Zhang
- KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, B-3001 Leuven, Belgium`; KU Leuven, Department of Oral Health Sciences, BIOMAT - Biomaterials Research Group & UZ Leuven (University Hospitals Leuven), Dentistry, Kapucijnenvoer 7 block a, B-3000 Leuven, Belgium.
| | - Mona Monzavi
- Periodontics and Ceramic Implantology (private Practice), 1401N Tustin Ave Suite #345, Santa Ana, CA 92705, USA
| | - Maoyin Li
- KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, B-3001 Leuven, Belgium`
| | - Stevan Čokić
- KU Leuven, Department of Oral Health Sciences, BIOMAT - Biomaterials Research Group & UZ Leuven (University Hospitals Leuven), Dentistry, Kapucijnenvoer 7 block a, B-3000 Leuven, Belgium
| | - Al Manesh
- Mission Dental Implant Center (private Practice), 26800 Crown Valley Pkwy Ste 425, Mission Viejo, CA 92691, USA
| | - Hessam Nowzari
- Periodontics and Implant Dentistry (private practice), 120 S Spalding Dr #201, Beverlyhills, CA 90210, USA
| | - Jef Vleugels
- KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, B-3001 Leuven, Belgium`
| | - Bart Van Meerbeek
- KU Leuven, Department of Oral Health Sciences, BIOMAT - Biomaterials Research Group & UZ Leuven (University Hospitals Leuven), Dentistry, Kapucijnenvoer 7 block a, B-3000 Leuven, Belgium
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Skjold A, Schriwer C, Gjerdet NR, Øilo M. Fractographic analysis of 35 clinically fractured bi-layered and monolithic zirconia crowns. J Dent 2022; 125:104271. [PMID: 36041673 DOI: 10.1016/j.jdent.2022.104271] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/12/2022] [Accepted: 08/25/2022] [Indexed: 10/15/2022] Open
Abstract
OBJECTIVES The aim of this retrieval study was to analyze the fracture features and identify the fracture origin of zirconia-based single crowns that failed during clinical use. METHODS Thirty-five fractured single crowns were retrieved from dental practices (bi-layered, n=15; monolithic, n=20). These were analyzed according to fractographic procedures by optical and scanning electron microscopy to identify fracture patterns and fracture origins. The fracture origins were closely examined. The crown margin thickness and axial wall height were measured. RESULTS Three types of failure modes were observed: total fractures, marginal semilunar fractures, and incisal chippings. Most of the crowns (23) had fracture origins at the crown margin and seven of them had defects in the fracture origin area. The exact fracture origin was not possible to identify due to missing parts in four crowns. The crown wall thickness was 20% thinner and wall height 30% shorter in the fracture origin area compared to the opposite side. CONCLUSIONS The findings in this study show that fractography can reveal fracture origins and fracture modes of both monolithic and bi-layered dental zirconia. The findings indicate that the crown margin on the shortest axial wall is the most common fracture origin site. CLINICAL SIGNIFICANCE Crown design factors such as material thickness at the margin, axial wall height and preparation type affects the risk of fracture. It is important to ensure that the crown margins are even and flawless.
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Affiliation(s)
- Anneli Skjold
- Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, Aarstadveien 19. N-5009 Bergen, Norway.
| | - Christian Schriwer
- Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, Aarstadveien 19. N-5009 Bergen, Norway.
| | - Nils Roar Gjerdet
- Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, Aarstadveien 19. N-5009 Bergen, Norway.
| | - Marit Øilo
- Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, Aarstadveien 19. N-5009 Bergen, Norway.
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Fracture Load and Fracture Patterns of Monolithic Three-Unit Anterior Fixed Dental Prostheses after In Vitro Artificial Aging-A Comparison between Color-Gradient and Strength-Gradient Multilayer Zirconia Materials with Varying Yttria Content. J Clin Med 2022; 11:jcm11174982. [PMID: 36078912 PMCID: PMC9457031 DOI: 10.3390/jcm11174982] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/18/2022] [Accepted: 08/19/2022] [Indexed: 12/02/2022] Open
Abstract
(1) Background: Due to advantages such as avoidance of chipping, pulp-friendly tooth preparation and cost reduction, zirconia is increasingly being used monolithically without veneering. Nevertheless, to enable good aesthetics, various multilayer systems have been developed. The aim of this study was to investigate the impact of different zirconia multilayer strategies and yttria levels on fracture load, fracture pattern, stress distribution and surface roughness. (2) Methods: Monolithic three-unit anterior FDPs were made from three different color-gradient zirconia multilayer materials with different yttria levels corresponding to varying strength and degrees of translucency grades (Katana HTML, STML, UTML, Kuraray) and one strength-gradient zirconia multilayer material (Katana YML, Kuraray) and artificially aged in a chewing simulator (1.2 × 106 load cycles, 50 N, 2 × 3000 thermocycles, 5−55 °C). Analyses of fracture load, fracture pattern, fracture surfaces, stress distribution and roughness were performed after the fracture load test. Shapiro−Wilk, Kruskal−Wallis, Mann−Whitney U-tests and one-way ANOVA were used (p < 0.05). (3) Results: Fracture loads of the high strength color-gradient material HTML and the strength-gradient material YML were comparable after 5 years of aging (p = 0.645). Increasing yttria levels resulted in a decrease in fracture resistance of 42−57% (p < 0.05). Surface roughness of different zirconia generations is comparable after polishing and aging. (4) Conclusions: Color-gradient multilayer zirconia materials and new strength-gradient zirconia materials with similar yttria levels in the basal layers show comparable mechanical properties and are suitable for anterior FDPs.
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In-lab simulation of CAD/CAM grinding and intaglio surface treatments of 4YSZ monolithic restorations: Effect on its load-bearing capacity under fatigue. J Mech Behav Biomed Mater 2022; 134:105417. [PMID: 36049370 DOI: 10.1016/j.jmbbm.2022.105417] [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: 06/29/2022] [Revised: 08/09/2022] [Accepted: 08/11/2022] [Indexed: 11/23/2022]
Abstract
OBJECTIVES To evaluate the effect of in-lab simulation of CAD/CAM grinding and intaglio surface treatments on the surface characteristics (topography and roughness) and fatigue behavior of adhesively luted 4YSZ simplified restorations. METHODS Ceramic discs (Ø = 10 mm, thickness = 1 mm) were randomly allocated into 6 groups considering: "In-lab simulation of CAD/CAM grinding" (ground or polished) and "intaglio surface treatments": Ctrl (without surface treatment), AlOx (aluminum oxide air abrasion) or GLZ (glaze spray application). The surface roughness of all samples was measured, the treated discs received a ceramic primer, were luted with resin cement onto a dentin analogue material (woven glass-reinforced epoxy resin) and tested under a cyclic fatigue test (step-stress approach, n = 15; 1.4 Hz, 10,000 cycles/step, step-size of 100N starting at 200N until failure). A complementary analysis was performed to corroborate the findings in the fatigue test that the glaze fill defects increase the mechanical properties of the ceramic. To do so, bars (n= 10; 1.0 × 1.0 × 12 mm; considering the groups: N-ID: non-indented; ID: indented; ID-GLZ: indented plus glaze spray application) were indented in a vickers hardness tester to produce a crack pattern, treated with glaze or not, and then submitted to flexural strength tests (FS). Fractographic and topographic analysis were performed. RESULTS In-lab simulation of CAD/CAM grinding decreased the fatigue failure load of the 4YSZ ceramic when comparing polished and ground groups, regardless of surface treatment. GLZ induced better fatigue performance compared to the air abrasion, regardless of the grinding condition (ground or polished surface). The results of the flexural strength test corroborated the findings in the fatigue test, as the ID-GLZ group presented superior FS than the ID group, however both had inferior FS than N-ID. There is an inverse association between roughness and fatigue failure load, as the higher the surface roughness, the lower the fatigue failure load. Failures in the fatigue and flexural strength tests started from the face subjected to tensile stresses. CONCLUSION In-lab simulation of CAD/CAM grinding had a detrimental effect on the fatigue behavior of 4YSZ and glaze spray induced better 4YSZ performance compared to the air abrasion. The intaglio surface treatments differently influenced the 4YSZ fatigue performance, however, only glaze spray can reverse the damage caused by the grinding.
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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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Mayinger F, Buser R, Laier M, Schönhoff LM, Kelch M, Hampe R, Stawarczyk B. Impact of the material and sintering protocol, layer thickness, and thermomechanical aging on the two-body wear and fracture load of 4Y-TZP crowns. Clin Oral Investig 2022; 26:6617-6628. [PMID: 35840737 DOI: 10.1007/s00784-022-04616-5] [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: 03/03/2022] [Accepted: 07/04/2022] [Indexed: 11/03/2022]
Abstract
OBJECTIVES The aim of this study is to investigate the influence of the material and corresponding sintering protocol, layer thickness, and aging on the two-body wear (2BW) and fracture load (FL) of 4Y-TZP crowns. MATERIALS AND METHODS Multi-layer 4Y-TZP crowns in three thicknesses (0.5 mm/1.0 mm/1.5 mm) were sintered by high-speed (Zolid RS) or conventional (Zolid Gen-X) sintering. 2BW of ceramic and enamel antagonist after aging (1,200,000 mechanical-, 6000 thermal-cycles) was determined by 3D-scanning before and after aging and subsequent matching to determine volume and height loss (6 subgroups, n = 16/subgroup). FL was examined initially and after aging (12 subgroups, n = 16/subgroup). Fractographic analyses were performed using light-microscope imaging. Global univariate analysis of variance, one-way ANOVA, linear regression, Spearman's correlation, Kolgomorov-Smirnov, Mann-Whitney U, and t test were computed (alpha = 0.05). Weibull moduli were determined. Fracture types were analyzed using Ciba Geigy table. RESULTS Material/sintering protocol did not influence 2BW (crowns: p = 0.908, antagonists: p = 0.059). High-speed sintered Zolid RS presented similar (p = 0.325-0.633) or reduced (p < 0.001-0.047) FL as Zolid Gen-X. Both 4Y-TZPs showed an increased FL with an increasing thickness (0.5(797.3-1429 N) < 1.0(2087-2634 N) < 1.5(2683-3715 N)mm; p < 0.001). For most groups, aging negatively impacted FL (p < 0.001-0.002). Five 0.5 mm specimens fractured, four showed cracks during and after aging. CONCLUSIONS High-speed sintered crowns with a minimum thickness of 1.0 mm showed sufficient mechanical properties to withstand masticatory forces, even after a simulated aging period of 5 years. CLINICAL RELEVANCE Despite the manufacturer indicating a thickness of 0.5 mm to be suitable for single crowns, a minimum thickness of 1.0 mm should be used to ensure long-term satisfactory results.
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Affiliation(s)
- Felicitas Mayinger
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany.
| | - Ramona Buser
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany.,Department of Reconstructive Dentistry and Gerodontology, University of Bern, Freiburgstrasse 7, 3007, Bern, Switzerland
| | - Maximilian Laier
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Lisa Marie Schönhoff
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Matthias Kelch
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Rüdiger Hampe
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
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Baldi A, Carossa M, Comba A, Alovisi M, Femiano F, Pasqualini D, Berutti E, Scotti N. Wear Behaviour of Polymer-Infiltrated Network Ceramics, Lithium Disilicate and Cubic Zirconia against Enamel in a Bruxism-Simulated Scenario. Biomedicines 2022; 10:biomedicines10071682. [PMID: 35884986 PMCID: PMC9313215 DOI: 10.3390/biomedicines10071682] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 11/16/2022] Open
Abstract
The present study aimed to evaluate the wear rate of polymer-infiltrated network composites and ceramics against enamel in a bruxism-simulated scenario. Ninety-six (n = 96) molars were divided into six groups (n = 16) according to their occlusal material: group 1—a polymer-infiltrated network ceramic (PINC); group 2—a second polymer-infiltrated network ceramic (PINC2); group 3—nanohybrid resin-based composite (CO); group 4—cubic zirconia (ZR); group 5—lithium disilicate (LS); and group 6—sound enamel (EN). A laser scanner was used to digitalize all of the occlusal surfaces before and after a fatigue test, which was conducted with a chewing simulator set at 80 N and semicircular movement in order to simulate bruxist movement and loads. Statistical analysis of volume loss was performed with a one-way ANOVA and post hoc Bonferroni test. ZR had significantly inferior wear to PINC (p ≤ 0.01) and CO (p = 0.04). LS wore the antagonist enamel significantly more than PINC, CO, PINC2 and EN (p ≤ 0.01). On the other hand, ZR wore the antagonist enamel significantly more than CO (p ≤ 0.01) and PINC2 (p = 0.05). In conclusion, PINCs better preserved antagonist enamel at the expense of a higher wear of their own. LS causes significantly higher enamel wear compared with PINCs. ZR caused significantly higher enamel wear compared with CO and PINC2, but it was wear-resistant.
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Affiliation(s)
- Andrea Baldi
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Massimo Carossa
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
- Correspondence:
| | - Allegra Comba
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Mario Alovisi
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Felice Femiano
- Restorative Dentistry, Multidisciplinary Department of Medical-Surgical and Dental Specialties, University of Study of Campania, “Luigi Vanvitelli”, Via De Crecchio 6, 83138 Naples, Italy;
| | - Damiano Pasqualini
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Elio Berutti
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
| | - Nicola Scotti
- Department of Surgical Sciences, CIR Dental School, University of Turin, Via Nizza 230, 10126 Turin, Italy; (A.B.); (A.C.); (M.A.); (D.P.); (E.B.); (N.S.)
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Ma Q, Ding Q, Zhang L, Sun Y, Xie Q. Surface characteristics and flexural strength of Porous-Surface designed zirconia manufactured via stereolithography. J Prosthodont 2022; 32:e81-e89. [PMID: 35778958 DOI: 10.1111/jopr.13565] [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: 05/02/2022] [Accepted: 06/17/2022] [Indexed: 12/01/2022] Open
Abstract
PURPOSE To design and fabricate zirconia bars with porous surfaces using stereolithography and evaluate their surface characteristics and flexural strengths. METHODS Five groups of zirconia bars (20 mm × 4 mm × 2 mm) with interconnected porous surfaces were designed and manufactured: (i) 400-μm pore size and 50% porosity (D400-P50 group), (ii) 400-μm pore size and 30% porosity (D400-P30 group), (iii) 200-μm pore size and 50% porosity (D200-P50 group), (iv) 200-μm pore size and 30% porosity (D200-P30 group), and (v) 100-μm pore size and 30% porosity (D100-P30 group). Zirconia bars without a porous surface (NP) were used as controls. The surface topographies and pore structures were investigated using scanning electron microscopy and three-dimensional laser microscopy. The printed porosity was calculated using the Archimedes method. Fifteen specimens from each group were subjected to a three-point bending test according to the ISO 6872:2015 standard. A Weibull analysis was performed, and the fractured surfaces were examined using scanning electron microscopy. RESULTS Zirconia bars with porous surfaces were designed and successfully manufactured. The designed pore size, porosity, and shape of the printed pores were approximately achieved for all the porous surfaces. The flexural strength of the control group was significantly higher than those of the groups with porous surfaces (p < 0.001). For the same porosity, groups with a pore size of 400 μm exhibited a lower flexural strength than the other groups (p<0.001). Additionally, for the same pore-size design, the flexural strengths of group D400-P50 and D400-P30 exhibited no significant differences (p = 0.150), while the flexural strengths of D200-P30 were significantly higher than that of D200-P50 group (p = 0.043). The control group and D400-P50 group had higher Weibull moduli than the other groups. The fractography of the specimens with porous surfaces indicated more than one crack origin, mainly owing to defects, including pores and cracks. CONCLUSION Zirconia bars with porous surfaces were successfully designed and fabricated using the stereolithography technique. Although porous surfaces may be advantageous for osteogenesis, the porous-surface design can reduce the flexural strength of the printed zirconia bars. By reducing the pore size, controlling the porosity, and improving the printing accuracy, a higher strength can be achieved. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Quanquan Ma
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, China
| | - Qian Ding
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, China.,Foshan (Southern China) Institute for New Materials, Guangdong, China
| | - Lei Zhang
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, China
| | - Yuchun Sun
- Center of Digital Dentistry, Peking University School and Hospital of Stomatology, Beijing, China.,National Engineering Laboratory for Digital and Material Technology of Stomatology, Research Center of Engineering and Technology for Digital Dentistry, Beijing, China
| | - Qiufei Xie
- Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center 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 Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Beijing, China
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Ordoñez Balladares A, Abad-Coronel C, Ramos JC, Martín Biedma BJ. Fracture Resistance of Sintered Monolithic Zirconia Dioxide in Different Thermal Units. MATERIALS 2022; 15:ma15072478. [PMID: 35407810 PMCID: PMC8999687 DOI: 10.3390/ma15072478] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/16/2022] [Accepted: 03/22/2022] [Indexed: 01/27/2023]
Abstract
The purpose of this study was to compare the fracture strength of monolithic zirconium dioxide subjected to a sintering process in two different furnaces: InFire HTC Speed and CEREC SpeedFire. Methods: Forty restorations were designed and machined using a computer aided design / computer aidded machine (CAD/CAM) system. The restorations were randomly assigned to two groups of 20 samples each, Group 1 for the SpeedFire furnace (fast sintering) and Group 2 for the InFire furnace (slow sintering). Each of the crowns was subjected to a maximum compression load recorded in Newtons (N) and a displacement control with a speed of 1 mm/min. Results: Group 1 presented an average of 1222.8 N and a standard deviation of 136.91 N. Group 2 obtained a mean of 1068.5 N and a standard deviation of 316.39 N. Conclusions: There were no significant differences between the two groups, and the mechanical strength of the material was not affected, which would imply a saving of clinical and laboratory time when performing rapid sintering on monolithic translucent zirconium dioxide restorations. However, rapidly sintered restorations have limited reliability.
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Affiliation(s)
- Andrea Ordoñez Balladares
- Faculty of Dentistry, Universidad de Guayaquil, Guayaquil 090514, Ecuador;
- Faculty of Dentistry, Universidad de Santiago de Compostela, 15782 Galicia, Spain;
| | - Cristian Abad-Coronel
- Department of Digital Dentistry and CAD/CAM Materials, Faculty of Dentistry, Universidad de Cuenca, Cuenca 010107, Ecuador
- Faculty of Dentistry, Universidad San Francisco de Quito, Quito 170901, Ecuador
- Correspondence:
| | - Joao Carlos Ramos
- Faculty of Medicine, Universidad de Coimbra, 3000-370 Coimbra, Portugal;
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Sailer I, Karasan D, Todorovic A, Ligoutsikou M, Pjetursson BE. Prosthetic failures in dental implant therapy. Periodontol 2000 2022; 88:130-144. [PMID: 35103329 PMCID: PMC9305548 DOI: 10.1111/prd.12416] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Both fixed and removable implant‐supported prostheses are well‐established methods for replacing missing teeth in partially or fully edentulous patients. Numerous systematic reviews have been performed in recent years to evaluate the survival and complication rates of implant‐retained fixed dental prostheses and implant‐retained overdentures, displaying high 5‐year survival rates ranging from 97.1% for fixed dental prostheses to 95%‐100% for implant‐retained overdentures. However, the survival rates only represent the prostheses remaining in use for a defined follow‐up time, and do not account for the potential prosthetic complications that may have arisen and influence the general success of the implant treatment. The most common technical complications of fixed implant‐retained single crowns are crown fracture, fractures of ceramic implant abutments, and esthetic problems. The predominant technical complication at multiple‐unit, implant‐retained fixed dental prostheses is fracture/chipping of the veneering ceramic. Reported technical complications for implant‐retained overdentures are overdenture fracture or chipping of the veneer materials, whereas mechanical complications include implant fracture, attachment failure, and attachment housing or insert complications. To reduce the risk of such failures, a comprehensive pretreatment diagnostic work‐up is essential, including defining the prosthetic goal with the aid of a wax‐up or set‐up and the associated ideal, prosthetically oriented three‐dimensional implant position. Furthermore, selection of the ideal type of prosthesis, including the respective implant components and materials, is important for clinical long‐term treatment success.
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Affiliation(s)
- Irena Sailer
- Division of Fixed Prosthodontics and Biomaterials, University Clinics for Dental Medicine, University of Geneva, Geneva, Switzerland
| | - Duygu Karasan
- Division of Fixed Prosthodontics and Biomaterials, University Clinics for Dental Medicine, University of Geneva, Geneva, Switzerland
| | - Ana Todorovic
- Division of Fixed Prosthodontics and Biomaterials, University Clinics for Dental Medicine, University of Geneva, Geneva, Switzerland.,Division of Prosthodontics, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia
| | - Maria Ligoutsikou
- Division of Fixed Prosthodontics and Biomaterials, University Clinics for Dental Medicine, University of Geneva, Geneva, Switzerland
| | - Bjarni Elvar Pjetursson
- Division of Fixed Prosthodontics and Biomaterials, University Clinics for Dental Medicine, University of Geneva, Geneva, Switzerland.,Department of Reconstructive Dentistry, Faculty of Odontology, University of Iceland, Reykjavik, Iceland
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Molnár J, Fráter M, Sáry T, Braunitzer G, Vallittu PK, Lassila L, Garoushi S. Fatigue performance of endodontically treated molars restored with different dentin replacement materials. Dent Mater 2022; 38:e83-e93. [DOI: 10.1016/j.dental.2022.02.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 01/06/2022] [Accepted: 02/19/2022] [Indexed: 01/08/2023]
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AlMutairi R, AlNahedh H, Maawadh A, Elhejazi A. Effects of Different Air Particle Abrasion Protocols on the Biaxial Flexural Strength and Fractography of High/Ultra-Translucent Zirconia. MATERIALS (BASEL, SWITZERLAND) 2021; 15:244. [PMID: 35009388 PMCID: PMC8745783 DOI: 10.3390/ma15010244] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/22/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
In this study, the biaxial flexural strength (BFS) and fractography of high/ultra-translucent monolithic zirconia ceramics subjected to different mechanical surface pretreatments were evaluated. A total of 108 disc-shaped samples (12 mm diameter, 1.2 mm thickness) of three zirconia materials (5Y-ZP KATANA Zirconia UTML (ML), 3Y-TZP DD Bio ZX2 (DB), and 5Y-ZP DD cube X2 (DC)) were used. The BFS was investigated after subjecting the samples to surface treatment using air abrasion particles of two types (aluminum oxide or glass microbeads). The data were analyzed using two-way analysis of variance, followed by Scheffe's post hoc test for multiple comparisons. The mean ± standard deviation BFS for DB was highest after treatment with 50 µm Al2O3 (1626.05 ± 31.9 MPa), with lower values being observed following treatment with 50 µm glass microbeads (1399.53 ± 24.2 MPa) and in the control sample (1198.51 ± 21.1 MPa). The mean ± standard deviation (SD) BFSs for DC and ML were the highest in the control groups. Surface air abrasion with 50 µm Al2O3 particles and 2 bar pressure is recommended for 3Y-TZP translucent zirconia, while no abrasion of 5Y-ZP translucent zirconia ceramic.
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Relationships between fracture toughness, Y2O3 fraction and phases content in modern dental Yttria-doped zirconias. Ann Ital Chir 2021. [DOI: 10.1016/j.jeurceramsoc.2021.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Velho HC, Dapieve KS, Valandro LF, Pereira GKR, Venturini AB. Cyclic fatigue tests on non-anatomic specimens of dental ceramic materials: A scoping review. J Mech Behav Biomed Mater 2021; 126:104985. [PMID: 34861521 DOI: 10.1016/j.jmbbm.2021.104985] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/15/2021] [Accepted: 11/18/2021] [Indexed: 11/16/2022]
Abstract
The aim of the present scoping review was to identify and discuss the methods, testing parameters, and characteristics used to induce cyclic fatigue on non-anatomic dental ceramic specimens. In vitro studies written in English which evaluated commercially-available non-anatomic dental ceramic specimens subjected to mechanical cyclic fatigue were selected. The search was performed in the PubMed, Scopus and Web of Science databases. The initial search yielded 1,636 articles, of which 81 were included. Based on the collected data, most of the included studies evaluated dental ceramic specimens cemented to supporting substrate (n= 42; 51.9%); used step-stress (n= 35; 42.2%) accelerated fatigue test, loading frequencies above 10 Hz (n= 31, 35.6%), stainless steel (n = 28, 32.6%) load applicator with spherical shaped tip 40 mm diameter (n= 25, 30.9%); applied only axial loads (n= 77, 95.1%); and considered a wet testing environment (n= 65, 78.3%). The definition of test geometry, method, and testing parameters must be cautiously considered according to the study objective and the scenario that is simulated. Accelerated fatigue tests, load frequencies up to 20 Hz, a 40 mm stainless steel spherical load applicator and a wet testing environment are the major common defined parameters presented in the existing literature. More studies exploring the influence of such factors on fatigue mechanism are necessary.
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Affiliation(s)
- Helder Callegaro Velho
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil.
| | - Kiara Serafini Dapieve
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, 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, Brazil.
| | - 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, Brazil.
| | - Andressa Borin Venturini
- MSciD and PhD Post-Graduate Program in Oral Science, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil.
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Fraga S, Pereira GKR, Guilardi LF, May LG, Valandro LF, Kleverlaan CJ. Influence of testing environment on static fatigue behavior of a glass and a polycrystalline ceramic. Braz Dent J 2021; 32:56-64. [PMID: 34755790 DOI: 10.1590/0103-6440202103961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 01/19/2021] [Indexed: 11/22/2022] Open
Abstract
It aims on evaluate the effect of the test environment on static fatigue behavior of lithium disilicate-based (LD), and yttrium oxide-stabilized zirconia (YSZ) ceramics. Specimens of LD (IPS e.max CAD, Ivoclar Vivadent) and YSZ (IPS e.max ZirCAD MO, 3 mol% Y2O3, Ivoclar Vivadent) were randomly allocated into three groups: tested in air, inert (paraffin oil, Sigma Aldrich) or distilled water. The static fatigue test (n=15) was performed using a piston-on-three ball assembly, adapted from ISO 6872, as follows: starting load 100 N for LD and 300 N for YSZ; loading application time set to 1 hour for each loading step; step size of 50 N for LD and 100 N for YSZ, applied successively until fracture. Data from static fatigue strength (MPa) and time to fracture (hours) were recorded. Fractographic analysis was executed. Survival analysis corroborates absence of influence of environment on static fatigue outcomes (fatigue strength, time to fracture and survival rates) for YSZ. For LD, specimens tested in air presented statistically superior survival rate and static fatigue strength (p= 0.025). In regards of time to fracture, LD tested in air were superior than when tested in distilled water (p=0.019) or inert (p=0.017) environments. No statistical differences for Weibull modulus were observed. Failures started on the tensile stress surface. Thus, the test environment did not affect slow crack growth (SCG) mechanisms during static fatigue test of YSZ ceramics, but it plays a significant role for the static fatigue behavior of lithium disilicate-based glass ceramics, indicating a high susceptibility to SCG.
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Affiliation(s)
- Sara Fraga
- Federal University of Rio Grande do Sul, Faculty of Dentistry, Department of Conservative Dentistry, Porto Alegre, RS, Brazil.
| | - Gabriel Kalil Rocha Pereira
- Federal University of Santa Maria, Faculty of Dentistry, Department of Restorative Dentistry, Santa Maria, RS, Brazil.
| | - Luís Felipe Guilardi
- Federal University of Santa Maria, Faculty of Dentistry, Department of Restorative Dentistry, Santa Maria, RS, Brazil.
| | - Liliana Gressler May
- Federal University of Santa Maria, Faculty of Dentistry, Department of Restorative Dentistry, Santa Maria, RS, Brazil.
| | - Luiz Felipe Valandro
- * Federal University of Santa Maria, Faculty of Dentistry, Department of Restorative Dentistry, Santa Maria, RS, Brazil.
| | - Cornelis Johannes Kleverlaan
- Academic Centre for Dentistry Amsterdam - ACTA, Department of Dental Materials Science, Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands.
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Shelar P, Abdolvand H, Butler S. On the behaviour of zirconia-based dental materials: A review. J Mech Behav Biomed Mater 2021; 124:104861. [PMID: 34600431 DOI: 10.1016/j.jmbbm.2021.104861] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 11/28/2022]
Abstract
Zirconia-based dental materials are extensively used in clinical practice due to their tooth-like appearance, biofunctionality, biocompatibility, and affordability. However, premature clinical failures of veneering porcelains raise a concern about their integrity. Extensive studies have been performed over a decade to resolve this issue, but it is challenging to reference all information effectively. A single source identifying the significance of potential parameters on material performance has not previously been available. An evidence-based meta-narrative review technique was used to review the characteristic parameters that can affect the overall behaviour of zirconia-based materials. Keywords were chosen to assess manuscripts based on scientific coherence with this paper's research objective. Online keyword searches were carried out on ScienceDirect, PubMed, and SAGE databases for relevant published manuscripts from year 1985-2020.261 out of 3170 identified manuscripts were included. A total of 10 parameters were identified and classified into the material, manufacturing, and geometric aspects. The effect of every parameter was reviewed on the performance of the material. A discrepancy in findings was observed and is attributed to the fact that there is no standard methodology. This review acts as a single source that summarizes various parameters' contribution to zirconia-based dental materials' performance. This review facilitates manufacturing improvements by accounting for every parameter's effect on overall performance.
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Affiliation(s)
- Prashant Shelar
- Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada
| | - Hamidreza Abdolvand
- Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada
| | - Sheila Butler
- Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
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Rodrigues CS, Dhital S, Kim J, May LG, Wolff MS, Zhang Y. Residual stresses explaining clinical fractures of bilayer zirconia and lithium disilicate crowns: A VFEM study. Dent Mater 2021; 37:1655-1666. [PMID: 34481666 DOI: 10.1016/j.dental.2021.08.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To understand the stress development in porcelain-veneered zirconia (PVZ) and porcelain-veneered lithium disilicate (PVLD) crowns with different veneer/core thickness ratios and cooling rates. To provide design guidelines for better performing bilayer restorations with the aid of Viscoelastic Finite Element Method (VFEM). METHODS The VFEM was validated by comparing the predicted residual stresses with experimental measurements. Then, the model was used to predict transient and residual stresses in the two bilayer systems. Models with two different veneer/core thickness ratios were prepared (2:1 and 1:1) and two cooling protocols were simulated (Fast: ∼300 °C/min, Slow: ∼30 °C/min) using the heat transfer module, followed by stress analysis in ABAQUS. The physical properties of zirconia, lithium disilicate, and the porcelains used for the simulations were determined as a function of temperature. RESULTS PVLD showed lower residual stresses than PVZ. The maximum tensile stresses in PVZ were observed in the cusp area, whereas those in PVLD were located in the central fossa. The 1:1 thickness ratio decreased stresses in both layers of PVZ. Slow cooling slightly decreased residual stresses in both systems. However, the cooling rate effect was more evident in transient stresses. SIGNIFICANCE Slow cooling is preferable for both systems. A thinner porcelain layer over zirconia lowers stresses throughout the restoration. The different stress distributions between PVZ and PVLD may affect their failure modes. Smaller mismatches in modulus, CTE, and specific heat between the constituents, and the use of low Tg porcelains can effectively reduce the deleterious transient and residual tensile stresses in bilayer restorations.
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Affiliation(s)
- Camila S Rodrigues
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University, 777 Eng. Francisco José Longo Av, 12245-000, São José dos Campos, SP, Brazil
| | - Sukirti Dhital
- Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Rd., U-3037, Storrs, CT 06269, USA
| | - Jeongho Kim
- Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Rd., U-3037, Storrs, CT 06269, USA
| | - Liliana Gressler May
- Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, 1000 Roraima Av., T Street, Building 26F, 97105-900, Santa Maria, RS, Brazil
| | - Mark S Wolff
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, 240 S. 40th Street, Philadelphia, PA 19104, USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, 240 S. 40th Street, Philadelphia, PA 19104, USA.
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Grzebieluch W, Kowalewski P, Grygier D, Rutkowska-Gorczyca M, Kozakiewicz M, Jurczyszyn K. Printable and Machinable Dental Restorative Composites for CAD/CAM Application-Comparison of Mechanical Properties, Fractographic, Texture and Fractal Dimension Analysis. MATERIALS 2021; 14:ma14174919. [PMID: 34501009 PMCID: PMC8434230 DOI: 10.3390/ma14174919] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/20/2021] [Accepted: 08/26/2021] [Indexed: 12/12/2022]
Abstract
Thanks to the continuous development of light-curing resin composites it is now possible to print permanent single-tooth restorations. The purpose of this study was to compare resin composites for milling -Gandio Blocks (GR), Brilliant Crios (CR) and Enamic (EN) with resin composite for 3D printing-Varseo Smile Crown plus (VSC). Three-point bending was used to measure flexural strength (σf) and flexural modulus (Ef). The microhardness was measured using a Vickers method, while fractographic, microstructural, texture and fractal dimension (FD) analyses were performed using SEM, optical microscope and picture analysis methods. The values of σf ranged from 118.96 (±2.81) MPa for EN to 186.02 (±10.49) MPa for GR, and the values of Ef ranged from 4.37 (±0.8) GPa for VSC to 28.55 (±0.34) GPa for EN. HV01 ranged from 25.8 (±0.7) for VSC to 273.42 (±27.11) for EN. The filler content ranged from 19-24 vol. % for VSC to 70-80 vol. % for GR and EN. The observed fractures are typical for brittle materials. The correlation between FD of materials microstructure and Ef was observed. σf of the printed resin depends on layers orientation and is significantly lower than σf of GR and CR. Ef of the printed material is significantly lower than Ef of blocks for milling.
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Affiliation(s)
- Wojciech Grzebieluch
- Laboratory for Digital Dentistry, Department of Conservative Dentistry Witch Endodontics, Wroclaw Medical University, Krakowska 26, 50-425 Wroclaw, Poland
- Correspondence: ; Tel.: +48-71-784-03-61
| | - Piotr Kowalewski
- Department of Fundamentals of Machine Design and Mechatronic Systems, Wroclaw University of Science and Technology, Lukasiewicza 7/9, 50-371 Wroclaw, Poland;
| | - Dominika Grygier
- Department of Vehicle Engineering, Faculty of Mechanical Engineering, Wroclaw University of Science and Technology, Lukasiewicza 5, 50-371 Wroclaw, Poland; (D.G.); (M.R.-G.)
| | - Małgorzata Rutkowska-Gorczyca
- Department of Vehicle Engineering, Faculty of Mechanical Engineering, Wroclaw University of Science and Technology, Lukasiewicza 5, 50-371 Wroclaw, Poland; (D.G.); (M.R.-G.)
| | - Marcin Kozakiewicz
- Department of Maxillofacial Surgery, Medical University of Lodz, 113 S. Zeromski Street, 90-549 Lodz, Poland;
| | - Kamil Jurczyszyn
- Department of Oral Surgery, Wroclaw Medical University, Krakowska 26, 50-425 Wroclaw, Poland;
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Increasing dental zirconia micro-retentive aspect through ultra-short pulsed laser microstructuring: study on flexural strength and crystal phase characterization. Clin Oral Investig 2021; 26:939-955. [PMID: 34402980 PMCID: PMC8791917 DOI: 10.1007/s00784-021-04077-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 07/10/2021] [Indexed: 11/13/2022]
Abstract
Objectives Although ultra-short pulsed laser (USPL) microstructuring has previously improved zirconia bond-strength, it is yet unclear how different laser-machined surface microstructures and patterns may influence the material’s mechanical properties. Therefore, the aim of this study was to assess the flexural strength of zirconia after different USPL settings creating three different geometrical patterns with structures in micrometer scale. Methods One hundred sixty zirconia bars (3Y-TZP, 21 × 4 × 2.1 mm) were prepared and randomly divided into five groups (n = 32): no surface treatment (negative control-NC); sandblasting with Al2O3 (SB); and three laser groups irradiated with USPL (Nd:YVO4/1064 nm/2-34 J/cm2/12 ps): crossed-lines (LC), random-hatching (LR), and parallel-waves (LW). Bars were subjected to a four-point flexural test (1 mm/min) and crystal phase content changes were identified by X-ray diffraction. Surface roughness and topography were analyzed through 3D-laser-profilometry and SEM. Data were analyzed with parametric tests for roughness and Weibull for flexural strength (α = 5%). Results LR (Mean[95%CI]: 852.0 MPa, [809.2–894.7]) was the only group that did not show a significantly different flexural strength than NC (819.8 MPa, [796.6–842.9]), (p > 0.05). All laser groups exhibited higher Weibull moduli than NC and SB, indicating higher reliability and homogeneity of the strength data. An increase of monoclinic phase peak was only observed for SB. Conclusion In conclusion, USPL created predictable, homogeneous, highly reproducible, and accurate surface microstructures on zirconia ceramic. The laser-settings of random-hatching (12 ps pulses) increased 3Y-TZP average surface roughness similarly to SB, while not causing deleterious crystal phase transformation or loss of flexural strength of the material. Furthermore, it has increased the Weibull modulus and consequently material’s reliability. Clinical significance Picosecond laser microstructuring (LR conditions) of 3Y-TZP ceramic does not decrease its flexural strength, while increasing materials realiability and creating highly reproducible and accurate microstructures. These features may be of interest both for improving clinical survival of zirconia restorations as well as enhancing longevity of zirconia implants.
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