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Huang B, Chen M, Wang J, Zhang X. Advances in zirconia-based dental materials: Properties, classification, applications, and future prospects. J Dent 2024; 147:105111. [PMID: 38866229 DOI: 10.1016/j.jdent.2024.105111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 06/04/2024] [Accepted: 06/06/2024] [Indexed: 06/14/2024] Open
Abstract
OBJECTIVES Zirconia (ZrO2) ceramics are widely used in dental restorations due to their superior mechanical properties, durability, and ever-improving translucency. This review aims to explore the properties, classification, applications, and recent advancements of zirconia-based dental materials, highlighting their potential to revolutionize dental restoration techniques. STUDY SELECTION, DATA AND SOURCES The most recent literature available in scientific databases (PubMed and Web of Science) reporting advances of zirconia-based materials within the dental field is thoroughly examined and summarized, covering the major keywords "dental zirconia, classification, aesthetic, LTD, applications, manufacturing, surface treatments". CONCLUSIONS An exhaustive overview of the properties, classifications, and applications of dental zirconia was presented, alongside an exploration of future prospects and potential advances. This review highlighted the importance of addressing challenges such as low-temperature degradation resistance and optimizing the balance between mechanical strength and translucency. Also, innovative approaches to improve the performances of zirconia as dental material was discussed. CLINICAL SIGNIFICANCE This review provides a better understanding of zirconia-based dental biomaterials for dentists, helping them to make better choice when choosing a specific material to fabricate the restorations or to place the implant. Moreover, new generations of zirconia are still expected to make progress on key issues such as the long-term applications in dental materials while maintaining both damage resistance and aesthetic appeal, defining the directions for future research.
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Affiliation(s)
- Bo Huang
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China
| | - Mengbing Chen
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China
| | - Jian Wang
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China.
| | - Xin Zhang
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China.
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Zhu H, Jiang J, Wang Y, Wang S, He Y, He F. Additive manufacturing of dental ceramics in prosthodontics: The status quo and the future. J Prosthodont Res 2024; 68:380-399. [PMID: 38346729 DOI: 10.2186/jpr.jpr_d_23_00119] [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] [Indexed: 07/09/2024]
Abstract
PURPOSE This review aims to summarize the available technologies, material categories, and prosthodontic applications of additive manufacturing (AM) dental ceramics, evaluate the achievable accuracy and mechanical properties in comparison with current mainstream computer-aided design/computer-aided manufacturing (CAD/CAM) subtractive manufacturing (SM) methods, and discuss future prospects and directions. STUDY SELECTION This paper is based on the latest reviews, state-of-the-art research, and existing ISO standards on AM technologies and prosthodontic applications of dental ceramics. PubMed, Web of Science, and ScienceDirect were amongst the sources searched for narrative reviews. RESULTS Relatively few AM technologies are available and their applications are limited to crowns and fixed partial dentures. Although the accuracy and strength of AM dental ceramics are comparable to those of SM, they have the limitations of relatively inferior curved surface accuracy and low strength reliability. Furthermore, functionally graded additive manufacturing (FGAM), a potential direction for AM, enables the realization of biomimetic structures, such as natural teeth; however, specific studies are currently lacking. CONCLUSIONS AM dental ceramics are not sufficiently developed for large-scale clinical applications. However, with additional research, it may be possible for AM to replace SM as the mainstream manufacturing technology for ceramic restorations.
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Affiliation(s)
- Han Zhu
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Jimin Jiang
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Yujie Wang
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Sijie Wang
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Yong He
- State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou, PR China
| | - Fuming He
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
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Zenthöfer A, Fien D, Rossipal J, Ilani A, Schmitt C, Hetzler S, Rammelsberg P, Rues S. Fracture Resistance of 3D-Printed Occlusal Veneers Made from 3Y-TZP Zirconia. MATERIALS (BASEL, SWITZERLAND) 2024; 17:2122. [PMID: 38730928 PMCID: PMC11084620 DOI: 10.3390/ma17092122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/18/2024] [Accepted: 04/26/2024] [Indexed: 05/13/2024]
Abstract
The aim of this paper was to evaluate the fracture resistance of 3D-printed zirconia occlusal veneers (OVs) of different thicknesses and supported by different abutment materials. Materials and Methods: The standard OV of a natural molar was prepared and digitized using a laboratory 3D scanner. The resulting digital tooth abutment was milled either using cobalt-chromium (CoCr) or a fiber-reinforced composite (FRC). All the abutments were digitized and standardized OVs (30° tilt of all the cusps) designed with 0.4 mm, 0.6 mm, or 0.8 mm wall thicknesses. The OVs were fabricated using either the Programill PM7 milling device (Ivoclar Vivadent, PM) or one of two 3D zirconia printers, Cerafab 7500 (Lithoz, LC) or Zipro-D (AON, ZD). The ZD samples were only tested on CoCr abutments. The completed OVs were luted to their abutments and subjected to artificial aging, consisting of thermocycling and chewing simulation before fracture testing with a steel sphere (d = 8 mm) as an antagonist with three contact points on the occlusal OV surface. Besides the total fracture resistance Fu,tot, the lowest contact force Fu,cont leading to the local fracture of a cusp was of interest. The possible effects of the factors fabrication approach, wall thickness, and abutment material were evaluated using ANOVA (α = 0.05; SPSS Ver.28). Results: The total fracture resistance/contact forces leading to failure ranged from Fu,tot = 416 ± 83 N/Fu,cont = 140 ± 22 N for the 0.4 mm OVs fabricated using LC placed on the FRC abutments to Fu,tot = 3309 ± 394 N (ZD)/Fu,cont = 1206 ± 184 N (PM) for the 0.8 mm thick OVs on the CoCr abutments. All the factors (the fabrication approach, abutment material, and OV wall thickness) had an independent effect on Fu,tot as well as Fu,cont (p < 0.032). In pairwise comparisons for Fu,tot of the OVs luted to the CoCr abutments, the ZD samples statistically outperformed the LC- and PM-fabricated teeth irrespective of the thickness (p < 0.001). Conclusions: Within the limitations of this study, the printed occlusal veneers exhibited comparable fracture resistances to those of the milled variants. However, more resilient abutments (FRC as a simulation of dentine) as well as a thinner wall thickness led to reduced OV fracture resistance, suggesting that 0.4 mm thick zirconia OVs should not be unreservedly used in every clinical situation.
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Affiliation(s)
- Andreas Zenthöfer
- Department of Prosthodontics, University of Heidelberg, 69120 Heidelberg, Germany; (D.F.); (J.R.); (S.H.); (P.R.); (S.R.)
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Handermann R, Zehender N, Rues S, Kobayashi H, Rammelsberg P, Schwindling FS. Load-bearing capacity of 3D-printed incisor partial-coverage crowns made from zirconia and composite. J Prosthodont Res 2024:JPR_D_23_00028. [PMID: 38684407 DOI: 10.2186/jpr.jpr_d_23_00028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
PURPOSE This study investigated the fracture resistance of 0.5-mm-thick restorations for minimally invasive therapy. Anterior partial-coverage crowns composed of three-dimensional (3D)-printed 3-mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP; Lithacon 3Y210, Lithoz) and 3D-printed composite (Varseo Smile Crown plus, Bego) were compared with a control group made from milled 3Y-TZP (Cercon ht, DentsplySirona). METHODS Three groups each with 27 restorations were produced. For milled 3Y-TZP partial-coverage crowns, drill compensation was needed so the milling bur could access the inner surface at the incisal edge. Restoration fit was verified by cross-sectioning 12 specimens in each group. The remaining 15 restorations were sandblasted (Al2O3, 0.1 MPa) and adhesively cemented (Panavia SA, Kuraray) onto CoCr teeth. Static load-to-failure tests were performed. The load was induced on the incisal edge. The forces needed to fracture the specimens were analyzed using the Welch analysis of variance and post hoc Dunnet-T3 tests. The Weibull parameters were also calculated. RESULTS Drill compensation increased cement thickness at the loading area by 200 µm in milled 3Y-TZP restorations compared with the 3D-printed partial-coverage crowns. Fracture resistance was the highest in 3D-printed 3Y-TZP restorations (1570±661N) followed by milled 3Y-TZP (886±164N) and 3D-printed composite partial-coverage crowns (570±233 N). Milled 3Y-TZP was associated with a substantially higher Weibull modulus (m=6) than the 3D-printed materials (m=2), suggesting greater reliability. CONCLUSIONS Fracture resistance increased with tighter fit, demonstrating the benefit of the geometric freedom associated with 3D-printing. Future research should focus on making 3D-printed 3Y-TZP more reliable to increase its safety in clinical use.
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Affiliation(s)
- Rebecca Handermann
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Nathalie Zehender
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Stefan Rues
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Hiro Kobayashi
- Department of Removable Partial Prosthodontics, Tokyo Dental College, Tokyo, Japan
| | - Peter Rammelsberg
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
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Rues S, Herpel C, Ilani A, Schmitt C, Rammelsberg P, Schwindling FS. Effect of firing time and wall thickness on the biaxial flexural strength of 3D-printed zirconia. Dent Mater 2024; 40:484-492. [PMID: 38155019 DOI: 10.1016/j.dental.2023.12.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 12/13/2023] [Accepted: 12/19/2023] [Indexed: 12/30/2023]
Abstract
OBJECTIVES To evaluate the effect of accelerated firing on 3D-printed zirconia. METHODS To check if formulae provided by ISO 6872 can be extended to thin samples, finite element analyses were carried out in advance of fabricating 3-mol% yttria-stabilized tetragonal zirconia polycrystal discs by milling and by 3D-printing. Four groups (n = 38 each) of 3D-printed specimens were produced with two nominal thicknesses (0.6 mm and 1.2 mm) and two firing strategies (long: 51 h, accelerated: 14.5 h). In the milled group (thickness 1.2 mm, n = 30), a standard firing program (9.8 h) was selected. Biaxial flexural strength tests were applied and mean strength, characteristic strength, and Weibull modulus were calculated for each group. Differences were analyzed using Welch ANOVA and Dunnett-T3 post-hoc tests. RESULTS Maximum tensile stresses occurring during biaxial strength testing can be calculated according to ISO 6872 for thin samples with b > 0.3 mm. Variability of measured strengths values was smaller for milled zirconia compared with 3D-printed zirconia. The 1.2-mm-thick 3D-printed samples had significantly decreased strength after accelerated firing than after long firing. However, for the 0.6-mm-thick samples, comparable mean biaxial strength values of about 1000 MPa were measured for both firing protocols. SIGNIFICANCE At the moment, long fabrication time for zirconia restorations is a major drawback of 3D-printing when compared with milling technology. This investigation showed that the strength of 0.6-mm-thick zirconia discs fabricated by 3D-printing was not impaired by accelerated firing. Thus, overnight firing of thin-walled 3D-printed zirconia restorations could be possible.
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Affiliation(s)
- Stefan Rues
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany.
| | - Christopher Herpel
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Ali Ilani
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Clemens Schmitt
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany; Department of Prosthetic Dentistry, Medical University Innsbruck, Innsbruck, Austria
| | - Peter Rammelsberg
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Franz Sebastian Schwindling
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany; Department of Prosthetic Dentistry, Medical University Innsbruck, Innsbruck, Austria
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Zenthöfer A, Ilani A, Schmitt C, Rammelsberg P, Hetzler S, Rues S. Biaxial flexural strength of 3D-printed 3Y-TZP zirconia using a novel ceramic printer. Clin Oral Investig 2024; 28:145. [PMID: 38351386 PMCID: PMC10864574 DOI: 10.1007/s00784-024-05533-5] [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: 11/15/2023] [Accepted: 01/29/2024] [Indexed: 02/16/2024]
Abstract
OBJECTIVES To compare the strength and reliability of 3D-printed 3Y-TZP zirconia manufactured with various printing orientations and staining. MATERIALS AND METHODS A total of one-hundred cylindrical zirconia specimens were designed and fabricated using 3D printing and processed according to ISO 6872 standards. Of these specimens, 80 were 3D printed using the new ZIPRO-D (ZD) 3D ceramic printer. In this ZD group, 60 specimens were printed in a vertical orientation and were either stained after debinding (ZD1, x-orientation, n = 20) or not stained (ZD2, x-orientation, n = 20; ZD3, y-orientation, n = 20) and the remaining 20 specimens out of n = 80 were printed in a horizontal orientation (ZD4). Further 20 specimens out of the entire sample N = 100 were printed vertically with the CeraFab7500 3D ceramic printer (LC). All completed specimens were loaded until fracture using a universal testing machine. Biaxial flexural strengths and Weibull parameters were computed for the ZD groups and for the LC group. Group and sub-group effects were evaluated using Welch ANOVA (alpha = 0.05). RESULTS The mean (standard deviation, SD) biaxial flexural strengths of vertically oriented ZD samples with (ZD1) and without (ZD2/ZD3) staining were 811 (197) and 850 (152) MPa, respectively (p > 0.05). The ZD4 (horizontally printed), 1107 (144) MPa, and LC (1238 (327)) MPa samples had higher mean (SD) flexural strengths than the ZD1-3 specimens. No difference was observed between the ZD4 and LC group (p > 0.05). Weibull moduli were between m = 4.6 (ZD1) and 9.1 (ZD4) in the ZD group and m = 3.5 in the LC group. CONCLUSIONS All tested 3D-printed zirconia specimens exceeded the flexural strengths required for class 5 restorations according to ISO 6872 standards. While the flexural strengths of zirconia printed using the novel ZD device in the vertical orientation are lower than those of zirconia printed using the LC printer, the ZD printer shows at least comparable reliability. CLINICAL RELEVANCE 3D-printing of zirconia is a new technology in dental application. Based on the presented strengths values, clinical application of 3D-printed zirconia for fixed dental protheses can be recommended.
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Affiliation(s)
- Andreas Zenthöfer
- Department of Prosthodontics, University Clinic Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany.
| | - Ali Ilani
- Department of Prosthodontics, University Clinic Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany
| | - Clemens Schmitt
- Department of Prosthodontics, University Clinic Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany
| | - Peter Rammelsberg
- Department of Prosthodontics, University Clinic Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany
| | - Sebastian Hetzler
- Department of Prosthodontics, University Clinic Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany
| | - Stefan Rues
- Department of Prosthodontics, University Clinic Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany
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Li M, Huang S, Willems E, Soete J, Inokoshi M, Van Meerbeek B, Vleugels J, Zhang F. UV-Curing Assisted Direct Ink Writing of Dense, Crack-Free, and High-Performance Zirconia-Based Composites With Aligned Alumina Platelets. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2306764. [PMID: 37986661 DOI: 10.1002/adma.202306764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/02/2023] [Indexed: 11/22/2023]
Abstract
Additive manufacturing (AM) of high-performance structural ceramic components with comparative strength and toughness as conventionally manufactured ceramics remains challenging. Here, a UV-curing approach is integrated in direct ink writing (DIW), taking advantage from DIW to enable an easy use of high solid-loading pastes and multi-layered materials with compositional changes; while, avoiding drying problems. UV-curable opaque zirconia-based slurries with a solid loading of 51 vol% are developed to fabricate dense and crack-free alumina-toughened zirconia (ATZ) containing 3 wt% alumina platelets. Importantly, a non-reactive diluent is added to relieve polymerization-induced internal stresses, avoid subsequent warping and cracking, and facilitate the de-binding. For the first time, UV-curing assisted DIW-printed ceramic after sintering reveals even better mechanical properties than that processed by a conventional pressing. This is attributed to the aligned alumina platelets, enhancing crack deflection and improving the fracture toughness from 6.8 ± 0.3 MPa m0.5 (compacted) to 7.4 ± 0.3 MPa m0.5 (DIW). The four-point bending strength of the DIW ATZ (1009 ± 93 MPa) is also higher than that of the conventionally manufactured equivalent (861 ± 68 MPa). Besides homogeneous ceramic, laminate structures are demonstrated. This work provides a valuable hybrid approach to additively manufacture tough and strong ceramic components.
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Affiliation(s)
- Maoyin Li
- Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, Leuven, B-3001, Belgium
- Department of Oral Health Sciences, KU Leuven, BIOMAT - Biomaterials Research group and UZ Leuven (University Hospitals Leuven), Dentistry, Kapucijnenvoer 7 block a, Leuven, B-3000, Belgium
| | - Shuigen Huang
- Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, Leuven, B-3001, Belgium
| | - Evita Willems
- Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, Leuven, B-3001, Belgium
| | - Jeroen Soete
- Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, Leuven, B-3001, Belgium
| | - Masanao Inokoshi
- Department of Gerodontology and Oral Rehabilitation, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo, 113-8549, Japan
| | - Bart Van Meerbeek
- Department of Oral Health Sciences, KU Leuven, BIOMAT - Biomaterials Research group and UZ Leuven (University Hospitals Leuven), Dentistry, Kapucijnenvoer 7 block a, Leuven, B-3000, Belgium
| | - Jef Vleugels
- Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, Leuven, B-3001, Belgium
| | - Fei Zhang
- Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, Leuven, B-3001, Belgium
- Department of Oral Health Sciences, KU Leuven, BIOMAT - Biomaterials Research group and UZ Leuven (University Hospitals Leuven), Dentistry, Kapucijnenvoer 7 block a, Leuven, B-3000, Belgium
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Hajjaj MS, Alamoudi RAA, Babeer WA, Rizg WY, Basalah AA, Alzahrani SJ, Yeslam HE. Flexural strength, flexural modulus and microhardness of milled vs. fused deposition modeling printed Zirconia; effect of conventional vs. speed sintering. BMC Oral Health 2024; 24:38. [PMID: 38185744 PMCID: PMC10771678 DOI: 10.1186/s12903-023-03829-8] [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: 10/17/2023] [Accepted: 12/26/2023] [Indexed: 01/09/2024] Open
Abstract
BACKGROUND Various methods can be used for creating zirconia dental restorations, including 3-dimensional (3D) printing and computer-aided design/ computer-aided manufacturing (CAD/CAM) milling. The fused deposition modeling (FDM) printing method for zirconia presents numerous advantages, albeit research on the mechanical properties of these materials and resultant restorations remains scarce. Such developments are undeniably intriguing and warrant further investigation. The objective of the present study was to evaluate the impact of the sintering firing cycle (Conventional vs. Speed sintering) on the flexural strength, flexural modulus, and Vickers Microhardness of milled vs. FDM printed zirconia. METHODS A total of 60 bars (2 × 5 × 27 mm) were fabricated for flexural strength testing, along with 40 discs (12 × 1.5 mm) for Vickers microhardness testing. Half of the specimens underwent conventional sintering, while the other half underwent a speed sintering cycle. The flexural strength and modulus were determined by a three-point bending test in a universal testing machine. The microhardness of the specimens was evaluated using a Vickers microhardness tester. Statistical analysis was performed using a two-way ANOVA test with a post-hoc Tukey test (p < 0.05). RESULTS CAD/CAM milled zirconia had significantly higher flexural strength and modulus than FDM-printed zirconia. The sintering process did not significantly affect the flexural strength or modulus of milled or FDM-printed zirconia. The milled speed sintering group had significantly higher values in the Vickers microhardness test compared to the other groups. CONCLUSIONS The mechanical properties of FDM-printed zirconia specimens were not found to be comparable to those of milled zirconia. Speed sintering cycle may produce milled zirconia restorations with similar flexural strength and modulus to conventional sintering, and even higher Vickers Microhardness values.
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Affiliation(s)
- Maher S Hajjaj
- Department of Restorative Dentistry, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia.
- Advanced Technology Dental Research Laboratory, King Abdulaziz University, P.O. Box 80209, Jeddah, 21589, Saudi Arabia.
| | - Rana A A Alamoudi
- Prosthodontic Master Student, Department of Oral and Maxillofacial Rehabilitation, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Walaa A Babeer
- Department of Oral and Maxillofacial Rehabilitation, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Waleed Y Rizg
- Department of Pharmaceutics, Faculty of Pharmacy, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
- Center of Innovation in Personalized Medicine (CIPM), 3D Bioprinting Unit, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
| | - Ahmad A Basalah
- Mechanical Engineering Department, College of Engineering and Architecture, Umm Al Qura University, Makkah, Saudi Arabia
| | - Saeed J Alzahrani
- Department of Restorative Dentistry, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Hanin E Yeslam
- Department of Restorative Dentistry, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
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Frąckiewicz W, Szymlet P, Jedliński M, Światłowska-Bajzert M, Sobolewska E. Mechanical characteristics of zirconia produced additively by 3D printing in dentistry - A systematic review with meta-analysis of novel reports. Dent Mater 2024; 40:124-138. [PMID: 37940500 DOI: 10.1016/j.dental.2023.10.020] [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: 05/17/2023] [Accepted: 10/20/2023] [Indexed: 11/10/2023]
Abstract
OBJECTIVES This study was aimed at comparing the mechanical parameters of ceramics made using the addition and subtraction technique. METHODS A search was performed on four search engines on 5th April 2023. Quality assessment was performed using study type-specific scales. Where possible, a meta-analysis was performed. SOURCES Data were extracted from four search engines: PubMed, PubMed Central, Embase, Web of Science, Scopus. STUDY SELECTION The search strategy identified 686 potential articles. 19 papers were subject to qualitative analysis, and data from 11 papers were meta-analysed. The included studies were of high or medium quality. All included papers were in-vitro studies. No clinical trials were found in the literature. SIGNIFICANCE Ceramics made in the additive technology in terms of mechanical parameters can compete with ceramics made in the milling technology. There are no clinical studies yet that would indicate the use of this type of material for permanent restorations in patients. Studies presented in the literature vary greatly in terms of study design and reporting of results. The research did not receive external funding.
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Affiliation(s)
- Wojciech Frąckiewicz
- Department of Dental Prosthetics, Faculty of Medicine and Dentistry, Pomeranian Medical University in Szczecin, 70-111 Szczecin, Poland.
| | - Paweł Szymlet
- Department of Dental Prosthetics, Faculty of Medicine and Dentistry, Pomeranian Medical University in Szczecin, 70-111 Szczecin, Poland
| | - Maciej Jedliński
- Department of Interdisciplinary Dentistry, Faculty of Medicine and Dentistry, Pomeranian Medical University in Szczecin, 70-111 Szczecin, Poland
| | - Małgorzata Światłowska-Bajzert
- Department of Dental Prosthetics, Faculty of Medicine and Dentistry, Pomeranian Medical University in Szczecin, 70-111 Szczecin, Poland
| | - Ewa Sobolewska
- Department of Dental Prosthetics, Faculty of Medicine and Dentistry, Pomeranian Medical University in Szczecin, 70-111 Szczecin, Poland
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Kim SH, Oh NS, Pang NS, Jung BY. The effect of surface treatment and low-temperature degradation on flexural strength of additive manufactured zirconia. J Mech Behav Biomed Mater 2023; 148:106167. [PMID: 37837875 DOI: 10.1016/j.jmbbm.2023.106167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 10/16/2023]
Abstract
This study aimed to assess the effect of low-temperature degradation (LTD) and surface treatment on the flexural strength of additive-manufactured (AM) zirconia by comparison to subtractive-manufactured (SM) zirconia. Disc-shaped zirconia specimens were fabricated using AM and SM technology, and each group was assigned to 3 subgroups according to the type of surface treatment: control, sandblasting (SB), and 9% hydrofluoric acid etching (HF). The groups were then further divided into 2 subgroups: unaged and aged. Biaxial flexural strength, crystal phase, surface topography, and surface roughness were measured to evaluate the mechanical properties. Statistical analyses were performed with 3-way ANOVA, followed by the comparison of means with Bonferroni post hoc analyses. The means and standard deviations of the biaxial flexural strength and Weibull parameters were calculated with descriptive statistics. All SM groups showed significantly greater flexural strength than the AM groups (p < .05), and LTD did not affect flexural strength except for the SMHF group (p < .05). After LTD, monoclinic phases (m-phase) were found in all groups, and SEM images showed grain pullout due to zirconia volume expansion in both control groups. Sandblasting significantly affected flexural strength (p < .05), whereas the HF group did not affect flexural strength except in the SMHF group after LTD (p < .05). No significant difference was observed in the surface roughness of AM compared to SM groups conditioned with the same surface treatment regardless of LTD. AM zirconia has comparable mechanical properties to SM zirconia, regardless of low-temperature degradation and surface treatment, which indicates the potential of the AM technique for clinical applications.
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Affiliation(s)
- So-Hyun Kim
- Department of Dentistry, Inha University School of Medicine, Inha University Hospital, Incheon, South Korea.
| | - Nam-Sik Oh
- Department of Dentistry, Inha University School of Medicine, Inha University Hospital, Incheon, South Korea.
| | - Nan-Sim Pang
- Department of Advanced General Dentistry, Yonsei University, College of Dentistry, Seoul, South Korea.
| | - Bock-Young Jung
- Department of Advanced General Dentistry, Yonsei University, College of Dentistry, Seoul, South Korea.
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11
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Miura S, Shinya A, Ishida Y, Fujita T, Vallittu P, Lassila L, Fujisawa M. The effect of low-temperature degradation and building directions on the mechanical properties of additive-manufactured zirconia. Dent Mater J 2023; 42:800-805. [PMID: 37793824 DOI: 10.4012/dmj.2023-089] [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] [Indexed: 10/06/2023]
Abstract
This study aimed to investigate the effect of low-temperature degradation (LTD) on the mechanical properties of additive-manufactured zirconia. In addition, the mechanical properties of additive-manufactured were compared with those before aging under similar experimental conditions. This study prepared stereolithography apparatus fabricated zirconia specimens with flexural strength, modulus of elasticity, Vickers hardness, and fracture toughness. The specimen position data were set as parallel (0°), diagonal (45°), and perpendicular (90°) to the direction of the building. The LTD condition was 5 h under 134ºC and 0.2 MPa in an autoclave. It was found that the 0° direction differed significantly from all other conditions before and after aging, and the highest flexural strength was obtained when the additive specimen was manufactured perpendicular to the building direction. However, the results indicate that there is a negligible effect of aging on the mechanical properties of additive-manufactured zirconia.
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Affiliation(s)
- Shoko Miura
- Division of Fixed Prosthodontics, Department of Restorative and Biomaterials Sciences, Meikai University School of Dentistry
- Department of Biomaterials Science and Turku Clinical Biomaterials Center-TCBC, Institute of Dentistry, University of Turku
| | - Akikazu Shinya
- Department of Dental Materials Sciences, School of Life Dentistry at Tokyo, The Nippon Dental University
- Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, University of Turku
| | - Yoshiki Ishida
- Department of Dental Materials Sciences, School of Life Dentistry at Tokyo, The Nippon Dental University
| | - Takafumi Fujita
- Division of Fixed Prosthodontics, Department of Restorative and Biomaterials Sciences, Meikai University School of Dentistry
| | - Pekka Vallittu
- Department of Biomaterials Science and Turku Clinical Biomaterials Center-TCBC, Institute of Dentistry, University of Turku
- Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, University of Turku
- Welfare District of County of Southwest Finland
| | - Lippo Lassila
- Department of Biomaterials Science and Turku Clinical Biomaterials Center-TCBC, Institute of Dentistry, University of Turku
| | - Masanori Fujisawa
- Division of Fixed Prosthodontics, Department of Restorative and Biomaterials Sciences, Meikai University School of Dentistry
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12
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Giugliano TS, Zhang Y, Janal MN, Lim CH, Smith RM, Choi M. In vitro comparison of physical characteristics of milled versus printed zirconia discs. J Prosthodont 2023:10.1111/jopr.13778. [PMID: 37776103 PMCID: PMC10980599 DOI: 10.1111/jopr.13778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 09/25/2023] [Accepted: 09/27/2023] [Indexed: 10/01/2023] Open
Abstract
PURPOSE The purpose of this study was to compare the dimensional accuracy, translucency, and biaxial flexural strength of milled zirconia (MZ) versus 3D-printed zirconia (PZ) discs. MATERIALS & METHODS A circular disc measuring 14.0 mm in diameter and 1.20 mm in thickness was designed using computer-aided design (CAD) software. The resulting standard tessellation language (STL) file was used both as a control and to fabricate 36 zirconia (3Y-TZP) disc specimens (n = 36): 18 were milled (group MZ) and 18 were 3D-printed (group PZ). The diameter and thickness of each disc were measured using a digital caliper. Translucency was evaluated using a calibrated dental colorimeter. The flexural strength was determined using the piston-on-three-ball biaxial flexure test. All measurements were done by one blinded examiner. The statistical significance level was set to α = 0.05. RESULTS The MZ discs had significantly more accurate dimensions than the PZ discs in both diameter and thickness when compared to the control CAD software-designed disc. The MZ discs exhibited significantly higher translucency (translucency parameter (TP) = 16.95 ±0.36 vs. 9.24 ±1.98) and biaxial flexural strength (996.16 ±137.37 MPa vs. 845.75 ±266.16 MPa) than the PZ discs. Finally, MZ possessed a significantly higher Weibull modulus relative to PZ. CONCLUSIONS The results showed that the milled specimens achieved better dimensional accuracy and were more translucent, stronger, and less prone to failure than printed specimens.
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Affiliation(s)
- Thomas S. Giugliano
- Department of Prosthodontics, New York University College of Dentistry, New York, NY
| | - Yu Zhang
- Laboratories for Microstructure Physics & Mechanics of Materials, Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA
| | - Malvin N. Janal
- Department of Epidemiology & Health Promotion, New York University College of Dentistry, New York, NY
| | - Chek Hai Lim
- Laboratories for Microstructure Physics & Mechanics of Materials, Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA
| | - Ruby M. Smith
- Post-Graduate Student, Department of Prosthodontics, New York University College of Dentistry, New York, NY
| | - Mijin Choi
- Department of Prosthodontics, New York University College of Dentistry, New York, NY
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13
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Lu Y, Wang L, Dal Piva AMO, Tribst JPM, Nedeljkovic I, Kleverlaan CJ, Feilzer AJ. Influence of surface finishing and printing layer orientation on surface roughness and flexural strength of stereolithography-manufactured dental zirconia. J Mech Behav Biomed Mater 2023; 143:105944. [PMID: 37269603 DOI: 10.1016/j.jmbbm.2023.105944] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/27/2023] [Accepted: 05/28/2023] [Indexed: 06/05/2023]
Abstract
OBJECTIVE To evaluate the effect of surface finishing and printing layer orientation on the surface roughness and flexural strength of three-dimensionally (3D) printed 3 mol% yttria-stabilized zirconia manufactured by stereolithography (SLA). METHODS Ninety bar-shaped zirconia specimens (1 mm x 1 mm x 12 mm) were 3D-printed via SLA. After debinding and sintering, they were randomly divided according to the printing layer orientation: parallel (PR) or perpendicular (PD) to the tensile surface for bending test. Each group was submitted to a surface finishing protocol (n=15/group): unpolished (subgroup 0), with polished tensile surface (subgroup 1), and with polished lateral and tensile surfaces (subgroup 3). Roughness of tensile surface was determined using a contact sensor and surface morphology was analyzed under Scanning Electron Microscopy (SEM). Flexural strength, apparent elastic modulus, and Weibull parameters were assessed using a 3-point bending test. Fractured specimens were examined to identify failure origins. Finite element analysis was used to evaluate tensile stress peaks and failure risk. RESULTS PR orientation exhibited higher strength, higher apparent elastic modulus, higher maximum principal stress peaks, and lower failure risk. For both layer orientations, groups with polished lateral and tensile sides (PR3 and PD3) were the strongest. SEM revealed that polishing led to changes in defect type, location, and size. SIGNIFICANCE SLA zirconia shows different mechanical properties according to surface roughness and defects. Orienting the printed layers parallel to the tensile side improves its mechanical performance. Polishing can significantly improve its flexural strength. It is necessary to reduce the final product's surface roughness and large pores for its best performance.
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Affiliation(s)
- Y Lu
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, the Netherlands
| | - L Wang
- Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, School of Mechanical Engineering, Jiangnan University, Wuxi, 214122, Jiangsu, China; Institute of Advanced Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China
| | - A M O Dal Piva
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, the Netherlands.
| | - J P M Tribst
- Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, the Netherlands
| | - I Nedeljkovic
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, the Netherlands
| | - C J Kleverlaan
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, the Netherlands
| | - A J Feilzer
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, the Netherlands; Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, the Netherlands
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14
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Liebermann A, Schultheis A, Faber F, Rammelsberg P, Rues S, Schwindling FS. Impact of post printing cleaning methods on geometry, transmission, roughness parameters, and flexural strength of 3D-printed zirconia. Dent Mater 2023; 39:625-633. [PMID: 37179237 DOI: 10.1016/j.dental.2023.05.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 04/12/2023] [Accepted: 05/02/2023] [Indexed: 05/15/2023]
Abstract
OBJECTIVE To analyze the impact of different post printing cleaning methods on geometry, transmission, roughness parameters, and flexural strength of additively manufactured zirconia. METHODS Disc-shaped specimens (N = 100) were 3D-printed from 3 mol%-yttria-stabilized zirconia (material: LithaCon 3Y 210; printer: CeraFab 7500, Lithoz) and were cleaned with five different methods (n = 20): (A) 25 s of airbrushing with the dedicated cleaning solution (LithaSol 30®, Lithoz) and 1-week storage in a drying oven (40 °C); (B) 25 s airbrushing (LithaSol 30®) without drying oven; (C) 30 s ultrasonic bath (US) filled with Lithasol30®; (D) 300 s US filled with LithaSol 30®; (E) 30 s US filled with LithaSol 30® followed by 40 s of airbrushing (LithaSol 30®). After cleaning, the samples were sintered. Geometry, transmission, roughness (Ra, Rz), characteristic strengths (σ0), and Weibull moduli (m) were analyzed. Statistical analyses were performed using Kolmogorov-Smirnov-, t-, Kruskal-Wallis-, and Mann-Whitney-U-tests (α < 0.05). RESULTS Short US (C) resulted in the thickest and widest samples. Highest transmission was found for US combined with airbrushing (E, p ≤ 0.004), followed by D and B (same range, p = 0.070). Roughness was lowest for US combined with airbrushing (E, p ≤ 0.039), followed by A and B (same range, p = 0.172). A (σ0 = 1030 MPa, m = 8.2), B (σ0 = 1165 MPa, m = 9.8), and E (σ0 = 1146 MPa, m = 8.3) were significantly stronger (p < 0.001) and substantially more reliable than C (σ0 = 480 MPa, m = 1.9) and D (σ0 = 486 MPa, m = 2.1). SIGNIFICANCE For 3D-printed zirconia, cleaning strategy selection is important. Airbrushing (B) and short US combined with airbrushing (E) were most favorable regarding transmission, roughness, and strength. Ultrasonic cleaning alone was ineffective (short duration) or detrimental (long duration). Strategy E could be particularly promising for hollow or porous structures.
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Affiliation(s)
- A Liebermann
- Department of Prosthetic Dentistry, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
| | - A Schultheis
- Department of Prosthetic Dentistry, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - F Faber
- Department of Prosthetic Dentistry, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - P Rammelsberg
- Department of Prosthetic Dentistry, Heidelberg University Hospital, Heidelberg, Germany
| | - S Rues
- Department of Prosthetic Dentistry, Heidelberg University Hospital, Heidelberg, Germany
| | - F S Schwindling
- Department of Prosthetic Dentistry, Heidelberg University Hospital, Heidelberg, Germany; Department of Prosthetic Dentistry, Medical University Innsbruck, Innsbruck, Austria
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15
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Yoo LG, Pang NS, Kim SH, Jung BY. Mechanical properties of additively manufactured zirconia with alumina air abrasion surface treatment. Sci Rep 2023; 13:9153. [PMID: 37280320 DOI: 10.1038/s41598-023-36181-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 05/29/2023] [Indexed: 06/08/2023] Open
Abstract
This study aimed to evaluate the mechanical properties of zirconia fabricated using additive manufacturing technology and compare them to those of zirconia fabricated using subtractive manufacturing technology. Sixty disc-shaped specimens were fabricated for the additive (n = 30) and subtractive manufacturing groups (n = 30), and each group was divided into two subgroups according to their air-abrasion surface treatment: control (n = 15) and air-abrasion groups (n = 15). Mechanical properties including the flexural strength (FS), Vickers hardness, and surface roughness were determined, and the values were analyzed by one-way ANOVA and Tukey's post hoc test (α = 0.05). X-ray diffraction and scanning electron microscopy were used for phase analysis and surface topography evaluation, respectively. The SMA group exhibited the highest FS (1144.97 ± 168.1 MPa), followed by the SMC (944.58 ± 141.38 MPa), AMA (905.02 ± 111.38 MPa), and AMC groups (763.55 ± 68.69 MPa). The Weibull distribution showed the highest scale value (1213.55 MPa) in the SMA group, with the highest shape value in the AMA group (11.69). A monoclinic peak was not detected in both the AMC and SMC groups, but after air abrasion, the monoclinic phase content ([Formula: see text]) reached 9% in the AMA group, exceeding that in the SMA group (7%). The AM groups exhibited statistically lower FS values than those of the SM groups under the same surface treatment (p < 0.05). Air-abrasion surface treatment increased the monoclinic phase content and FS (p < 0.05) in both the additive and subtractive groups, while it increased the surface roughness (p < 0.05) only in the additive group and did not affect the Vickers hardness in either group. For zirconia manufactured using additive technology, the mechanical properties are comparable to those of zirconia manufactured using subtractive technology.
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Affiliation(s)
- Lee-Gang Yoo
- Department of Advanced General Dentistry, College of Dentistry, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, South Korea
| | - Nan-Sim Pang
- Department of Advanced General Dentistry, College of Dentistry, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, South Korea
| | - So-Hyun Kim
- Department of Dentistry, Inha University Hospital, Inha University School of Medicine, Incheon, Korea
| | - Bock-Young Jung
- Department of Advanced General Dentistry, College of Dentistry, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, South Korea.
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16
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Rues S, Zehender N, Zenthöfer A, Bömicke W, Herpel C, Ilani A, Erber R, Roser C, Lux CJ, Rammelsberg P, Schwindling FS. Fit of anterior restorations made of 3D-printed and milled zirconia: An in-vitro study. J Dent 2023; 130:104415. [PMID: 36640843 DOI: 10.1016/j.jdent.2023.104415] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 12/23/2022] [Accepted: 01/10/2023] [Indexed: 01/13/2023] Open
Abstract
OBJECTIVES To evaluate the fit of zirconia veneers made by either 3D printing or milling. METHODS A typodont maxillary central incisor was prepared for a 0.5-mm-thick veneer and was reproduced 36 times from resin. Restorations were designed with a 20-µm-wide marginal and a 60-µm-wide internal cement gap, and were made from 3D-printed zirconia (LithaCon 3Y 210, Lithoz, n = 24) and milled zirconia (Cercon ht, DentsplySirona, n = 12). For milled zirconia, a drill compensation was needed to give the milling bur access to the intaglio surface. The restorations were cemented, cross-sectioned, and the cement gap size was analyzed by two raters. Inter-rater reliability was studied at 12 3D-printed veneers (intraclass correlation coefficient, ICC, mixed model, absolute agreement). Twelve remaining 3D-printed restorations were compared with 12 milled restorations regarding fit at three locations: marginally, labially, and at the incisal edge (Mann-Whitney U-tests, α<0.05). RESULTS Inter-rater reliability was excellent, with an ICC single-measure coefficient of 0.944 (95%-confidence interval: [0.907; 0.966]). Gap sizes (mean ± SD / maximum) were 55 ± 9 / 143 µm at the margins, 68 ± 14 / 130 µm labially, and 78 ± 19 / 176 µm at the incisor edge for 3D-printed veneers. For milled veneers, gap sizes were 44 ± 11 / 141 µm at the margins, 85 ± 19 / 171 µm labially, and 391 ± 26 / 477 µm at the incisor edge. At the margins, the milled veneers outperformed the 3D-printed restorations (p = 0.011). The cement gap at the incisor edge was significantly smaller after 3D printing (p < 0.001). CONCLUSIONS 3D-printed zirconia restorations showed clinically acceptable mean marginal gaps below 100 µm. Because drill compensation could be omitted with 3D printing, the fit at the sharp incisal edge was significantly tighter than with milling. CLINICAL SIGNIFICANCE The fit of 3D-printed ceramic anterior restorations meets clinical standards. In addition, 3D printing is associated with a greater geometrical freedom than milling. With regard to fit this feature allows tighter adaptation even after minimally invasive preparation.
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Affiliation(s)
- Stefan Rues
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Nathalie Zehender
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Andreas Zenthöfer
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Wolfgang Bömicke
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Christopher Herpel
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Ali Ilani
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Ralf Erber
- Department of Orthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Christoph Roser
- Department of Orthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Christopher J Lux
- Department of Orthodontics, Heidelberg University Hospital, Heidelberg, Germany
| | - Peter Rammelsberg
- Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany
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