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Kim JH, Kwon JS, Park JM, Lo Russo L, Shim JS. Effects of postpolymerization conditions on the physical properties, cytotoxicity, and dimensional accuracy of a 3D printed dental restorative material. J Prosthet Dent 2024; 132:241-250. [PMID: 35778292 DOI: 10.1016/j.prosdent.2022.04.024] [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: 11/16/2021] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 10/17/2022]
Abstract
STATEMENT OF PROBLEM Although the introduction of high-speed 3-dimensional (3D) printing technology has significantly reduced printing time, the time required for postpolymerization is a speed-determining step because of the long wait time. How postpolymerization conditions affect material properties is unclear. PURPOSE The purpose of this in vitro study was to assess the physical properties, accuracy, and biosafety of a 3D printed dental restorative material according to postpolymerization conditions. MATERIAL AND METHODS Specimens were prepared by 3D printing with a digital light processing 3D printer with 1 interim dental material (C&B MFH). All printed specimens underwent a postpolymerization process with 5 different postpolymerization devices and were designated as groups D1 (D102H), FO (Form Cure), LC (LC-3DPrintBox), ME (Medusa), and MP (MP100). The light intensity and temperature of each device were measured, and the Vickers hardness, flexural strength and modulus, degree of conversion (DC), cytotoxicity, and polymerization shrinkage were analyzed. Statistical analyses were conducted with 1-way analysis of variance, the Tukey post hoc test, and regression testing (α=.05). Scanning electron microscopy was used to assess the fracture surface characteristics of the specimens. RESULTS Light intensity was strongest with the ME device, and the temperature inside the device during postpolymerization showed the highest increase with the LC device and the lowest increase with the D1 device. The LC group specimens showed the highest mean Vickers hardness, and the MP group showed the lowest. The flexural strength was ≥100 MPa in all groups, with a flexural modulus ranging from 1.17 to 1.5 GPa. The DC results were similar to the physical properties test results. The D1, FO, LC, and ME groups all showed ≥70% cell viability, indicating no toxicity. The FO group showed the highest shrinkage rate of 0.52%. CONCLUSIONS When the light intensity was strong, the surface was sufficiently hard, and toxic substances were not eluted even after a short postpolymerization time, suggesting that light intensity modulation and time management can be used to improve the postpolymerization process.
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Affiliation(s)
- Jang-Hyun Kim
- Postgraduate student, Department and Research Institute of Dental Biomaterials and Bioengineering, Oral Research Science Center, BK21 FOUR Project, Yonsei University College of Dentistry, Seoul, Republic of Korea; Researcher, Department of Prosthodontics, Yonsei University College of Dentistry, Seoul, Republic of Korea
| | - Jae-Sung Kwon
- Assistant Professor, Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, Seoul, Republic of Korea
| | - Ji-Man Park
- Associate Professor, Department of Prosthodontics & Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea.
| | - Lucio Lo Russo
- Associate Professor, Department of Clinical and Experimental Medicine, School of Dentistry, University of Foggia, Foggia, Italy
| | - June-Sung Shim
- Professor, Department of Prosthodontics, Yonsei University College of Dentistry, Seoul, Republic of Korea
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2
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Rengarajan V, Clyde A, Pontsler J, Valiente J, Peel A, Huang Y. Assessing Leachable Cytotoxicity of 3D-Printed Polymers and Facile Detoxification Methods. 3D PRINTING AND ADDITIVE MANUFACTURING 2023; 10:1110-1121. [PMID: 37873063 PMCID: PMC10593418 DOI: 10.1089/3dp.2021.0216] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Additive manufacturing of polymers is gaining momentum in health care industries by providing rapid 3D printing of customizable designs. Yet, little is explored about the cytotoxicity of leachable toxins that the 3D printing process introduced into the final product. We studied three printable materials, which have various mechanical properties and are widely used in stereolithography 3D printing. We evaluated the cytotoxicity of these materials through exposing two fibroblast cell lines (human and mouse derived) to the 3D-printed parts, using overlay indirect contact assays. All the 3D-printed parts were measured toxic to the cells in a leachable manner, with flexible materials more toxic than rigid materials. Furthermore, we attempted to reduce the toxicity of the 3D-printed material by employing three treatment methods (further curing, passivation coating, and Soxhlet solvent extraction). The Soxhlet solvent extraction method was the most effective in removing the leachable toxins, resulting in the eradication of the material's toxicity. Passivation coating and further curing showed moderate and little detoxification, respectively. Additionally, mechanical testing of the materials treated with extraction methods revealed no significant impacts on its mechanical performances. As leachable toxins are broadly present in 3D-printed polymers, our cytotoxicity evaluation and reduction methods could aid in extending the selections of biocompatible materials and pave the way for the translational use of 3D printing.
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Affiliation(s)
| | - Angela Clyde
- Department of Biological Engineering, Utah State University, Logan, Utah, USA
- Institute of Antiviral Research, Utah State University, Logan, Utah, USA
| | - Jefferson Pontsler
- Department of Biological Engineering, Utah State University, Logan, Utah, USA
| | - Jonathan Valiente
- Department of Biological Engineering, Utah State University, Logan, Utah, USA
| | - Adreann Peel
- Department of Biological Engineering, Utah State University, Logan, Utah, USA
| | - Yu Huang
- Department of Biological Engineering, Utah State University, Logan, Utah, USA
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3
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Gupta A, Alifui-Segbaya F, Hasanov S, White AR, Ahmed KE, Love RM, Fidan I. Material extrusion of thermoplastic acrylic for intraoral devices: Technical feasibility and evaluation. J Mech Behav Biomed Mater 2023; 143:105950. [PMID: 37285773 DOI: 10.1016/j.jmbbm.2023.105950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/09/2023]
Abstract
With global demand for 3D printed medical devices on the rise, the search for safer, inexpensive, and sustainable methods is timely. Herein, we assessed the practicality of the material extrusion process for acrylic denture bases of which successful outcomes can be extended to implant surgical guides, orthodontic splints, impression trays, record bases and obturators for cleft palates or other maxillary defects. Representative materials comprising denture prototypes and test samples were designed and built with in-house polymethylmethacrylate filaments using varying print directions (PDs), layer heights (LHs) and reinforcements (RFs) with short glass fiber. The study undertook a comprehensive evaluation of the materials to determine their flexural, fracture, and thermal properties. Additional analyses for tensile and compressive properties, chemical composition, residual monomer, and surface roughness (Ra) were completed for parts with optimum parameters. Micrographic analysis of the acrylic composites revealed adequate fiber-matrix compatibility and predictably, their mechanical properties improved simultaneously with RFs and decreased LHs. Fiber reinforcement also improved the overall thermal conductivity of the materials. Ra, on the other hand, improved visibly with decreased RFs and LHs and the prototypes were effortlessly polished and characterized with veneering composites to mimic gingival tissues. In terms of chemical stability, the residual methyl methacrylate monomer contents are well below standards threshold for biological reactions. Notably, 5 vol% acrylic composites built with 0.05 mm LH in 0° on z-axis produced optimum properties that are superior to those of conventional acrylic, milled acrylic and 3D printed photopolymers. Finite element modeling successfully replicated the tensile properties of the prototypes. It may well be argued that the material extrusion process is cost-effective; however, the speed of manufacturing could be longer than that of established methods. Although the mean Ra is within an acceptable range, mandatory manual finishing and aesthetic pigmentation are required for long-term intraoral use. At a proof-of-concept level, it is evident that the material extrusion process can be applied to build inexpensive, safe, and robust thermoplastic acrylic devices. The broad outcomes of this novel study are equally worthy of academic reflection, and further translation to the clinic.
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Affiliation(s)
- Ankit Gupta
- College of Engineering, Computer Science, and Technology, Department of Engineering and Technology, California State University, Los Angeles, USA.
| | - Frank Alifui-Segbaya
- School of Medicine and Dentistry, Ian O'Connor Building, Griffith Health, Gold Coast Campus, Griffith University, QLD, 4222, Australia.
| | - Seymur Hasanov
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
| | - Alan R White
- School of Environment and Science, Griffith Sciences, Nathan Campus, Griffith University, QLD, 4111, Australia.
| | - Khaled E Ahmed
- School of Medicine and Dentistry, Ian O'Connor Building, Griffith Health, Gold Coast Campus, Griffith University, QLD, 4222, Australia.
| | - Robert M Love
- School of Medicine and Dentistry, Ian O'Connor Building, Griffith Health, Gold Coast Campus, Griffith University, QLD, 4222, Australia.
| | - Ismail Fidan
- Tennessee Tech University, 920 N. Peachtree Avenue, MET Department, LEWS 103, Cookeville, TN, 38505-5003, USA.
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Lee HE, Alauddin MS, Mohd Ghazali MI, Said Z, Mohamad Zol S. Effect of Different Vat Polymerization Techniques on Mechanical and Biological Properties of 3D-Printed Denture Base. Polymers (Basel) 2023; 15:polym15061463. [PMID: 36987243 PMCID: PMC10051857 DOI: 10.3390/polym15061463] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/09/2023] [Accepted: 03/14/2023] [Indexed: 03/18/2023] Open
Abstract
Three-dimensional printing is increasingly applied in dentistry to fabricate denture bases. Several 3D-printing technologies and materials are available to fabricate denture bases, but there is data scarcity on the effect of printability, mechanical, and biological properties of the 3D-printed denture base upon fabricating with different vat polymerization techniques. In this study, the NextDent denture base resin was printed with the stereolithography (SLA), digital light processing (DLP), and light-crystal display (LCD) technique and underwent the same post-processing procedure. The mechanical and biological properties of the denture bases were characterized in terms of flexural strength and modulus, fracture toughness, water sorption and solubility, and fungal adhesion. One-way ANOVA and Tukey’s post hoc were used to statistically analyze the data. The results showed that the greatest flexural strength was exhibited by the SLA (150.8±7.93 MPa), followed by the DLP and LCD. Water sorption and solubility of the DLP are significantly higher than other groups (31.51±0.92 μgmm3) and 5.32±0.61 μgmm3, respectively. Subsequently, the most fungal adhesion was found in SLA (221.94±65.80 CFU/mL). This study confirmed that the NextDent denture base resin designed for DLP can be printed with different vat polymerization techniques. All of the tested groups met the ISO requirement aside from the water solubility, and the SLA exhibited the greatest mechanical strength.
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Affiliation(s)
- Hao-Ern Lee
- Faculty of Dentistry, Universiti Sains Islam Malaysia, Kuala Lumpur 56100, Malaysia
- Smart Manufacturing and Advanced Renewable Technology Research Group, Faculty Science and Technology, Universiti Sains Islam Malaysia, Nilai 71800, Malaysia
| | - Muhammad Syafiq Alauddin
- Smart Manufacturing and Advanced Renewable Technology Research Group, Faculty Science and Technology, Universiti Sains Islam Malaysia, Nilai 71800, Malaysia
- Department of Conservative Dentistry and Prosthodontics, Universiti Sains Islam Malaysia, Kuala Lumpur 56100, Malaysia
- Correspondence:
| | - Mohd Ifwat Mohd Ghazali
- Smart Manufacturing and Advanced Renewable Technology Research Group, Faculty Science and Technology, Universiti Sains Islam Malaysia, Nilai 71800, Malaysia
| | - Zulfahmi Said
- Department of Basic Sciences and Oral Biology, Faculty of Dentistry, Universiti Sains Islam Malaysia, Kuala Lumpur 56100, Malaysia
| | - Syazwani Mohamad Zol
- Faculty of Dentistry, Universiti Sains Islam Malaysia, Kuala Lumpur 56100, Malaysia
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Nam NE, Hwangbo NK, Jin G, Shim JS, Kim JE. Effects of heat-treatment methods on cytocompatibility and mechanical properties of dental products 3D-printed using photopolymerized resin. J Prosthodont Res 2023; 67:121-131. [PMID: 35570000 DOI: 10.2186/jpr.jpr_d_21_00345] [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] [Indexed: 01/12/2023]
Abstract
PURPOSE The purpose of this study was to test heat-treatment methods for improving the cytocompatibility of dental 3D printable photopolymer resins. METHODS Nextdent C&B resin and a digital light processing 3D printer were used to print all specimens, which were divided into seven groups as follows: 1-month storage at controlled room temperature, 20 to 25 °C (RT), 24-hour storage at RT, 24-hour storage in RT water, 1-min immersion in 80 °C water, 1-min immersion in 100 °C water, 5-min immersion in 100 °C water, and autoclaving. Cell viability tests, cytotoxicity tests, and confocal laser scanning microscopy were performed to analyze the cytocompatibility of the 3D-printed resin. Fourier-transform infrared spectroscopy was performed after heat-treatment to determine the degree of conversion (DC). RESULTS Immersing printed resin samples in 100 °C water for 1 or 5 min after the curing process was an effective method for increasing cytocompatibility by inducing the preleaching of toxic substances such as unpolymerized monomers, photoinitiators, and additives. Moreover, the DC can be increased by additional polymerization without affecting the mechanical properties of the material. CONCLUSIONS Immersing the printed photosensitive dental resins in 100 °C water for 5 min is a suitable method for increasing cytocompatibility and the DC.
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Affiliation(s)
- Na-Eun Nam
- BK21 FOUR Project, Department of Prosthodontics, Yonsei University College of Dentistry, Korea
| | - Na-Kyung Hwangbo
- Department of Orofacial Pain and Oral Medicine, Yonsei University College of Dentistry, Korea
| | - Gan Jin
- Department of Prosthodontics, College of Dentistry, Yonsei University, Korea
| | - June-Sung Shim
- Department of Prosthodontics, College of Dentistry, Yonsei University, Korea
| | - Jong-Eun Kim
- Department of Prosthodontics, College of Dentistry, Yonsei University, Korea
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Okutan Y, Kandemir B, Donmez MB, Yucel MT. Effect of the thickness of CAD-CAM materials on the shear bond strength of light-polymerized resin cement. Eur J Oral Sci 2022; 130:e12892. [PMID: 35969188 DOI: 10.1111/eos.12892] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 07/19/2022] [Indexed: 11/29/2022]
Abstract
This study aimed to investigate the effect of the thickness of computer aided design-computer aided manufacturing (CAD-CAM) restorative materials on the bond strength of light-polymerized resin cement. Ninety specimens were prepared from three different CAD-CAM materials (a leucite-based glass-ceramic [Empress CAD], a polymer-infiltrated ceramic network [Vita Enamic], and a zirconia-reinforced lithium silicate glass-ceramic [Vita Suprinity]) in different thicknesses (1, 2, and 3 mm). One surface of each specimen was treated by using a single-step self-etching ceramic primer (Monobond Etch & Prime). Light-polymerized resin cement was bonded to treated surfaces by exposure to a light-emitting diode curing unit from the untreated side of the samples. Shear bond strength (SBS) between the ceramic and the resin cement was measured by using a universal testing machine. The leucite-based glass-ceramic had higher SBS values than the other materials at each thickness. For each material, 1 mm-thick specimens had the highest SBS values. The difference between the SBS values of 2 mm- and 3 mm-thick polymer-infiltrated ceramic network was nonsignificant, whereas the SBS values of 2 mm-thick leucite-based glass-ceramic and the zirconia-reinforced lithium silicate glass-ceramic were significantly higher than those of the corresponding 3 mm-thick specimens. The choice of the material and its thickness may be highly important for clinical success when light-polymerized resin cements are used for cementation.
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Affiliation(s)
- Yener Okutan
- Department of Prosthodontics, Faculty of Dentistry, Aydin Adnan Menderes University, Aydin, Turkey
| | - Banucicek Kandemir
- Department of Prosthodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey
| | - Mustafa Borga Donmez
- Department of Prosthodontics, Faculty of Dentistry, Istinye University, Istanbul, Turkey.,Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland
| | - Munir Tolga Yucel
- Department of Prosthodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey
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Abualsaud R, Gad M. Flexural strength of CAD/CAM denture base materials: Systematic review and meta-analysis of in-vitro studies. J Int Soc Prev Community Dent 2022; 12:160-170. [PMID: 35462750 PMCID: PMC9022382 DOI: 10.4103/jispcd.jispcd_310_21] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/11/2021] [Accepted: 12/22/2021] [Indexed: 11/25/2022] Open
Abstract
Introduction: Digital complete dentures fabrication techniques are expanding. This study aimed to review flexural strength (FS) of milled and 3D-printed denture base materials to answer the study question: is FS of computer-aided designing/computer-aided manufacturing (CAD/CAM) denture base comparable to conventional heat-polymerized materials? Materials and Methods: Search was done within different databases for articles published between January 2010 and June 2021 using specific keywords. Articles of in-vitro studies in English language with methods following International Standards Organization standardization/ADA specifications for flexural testing of conventional and CAD/CAM (milled or printed) polymethyl methacrylate (PMMA) materials were included. Results: Out of the 61 studies, 9 were processed for data extraction and only 7 underwent meta-analysis. Two, six, and one study showed high, moderate, and low risk of bias, respectively. Random-effects model was used for analysis and resulted in the average FS of 120.61 MPa [95% confidence interval (CI): 109.81−131.41] and 92.16 MPa (CI: 75.12−109.19) for CAD/CAM milled and heat-polymerized PMMA, respectively. Conclusion: Subtractive CAD/CAM technique of denture fabrication showed satisfactory FS values, whereas additive CAD/CAM method was comparable to conventional heat-polymerized technique with lower value, requiring further investigations and improvement. The clinical use of milled denture bases is an acceptable substitution to heat-polymerized PMMA, making the denture fabrication an easier and faster process.
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Xu Y, Xepapadeas AB, Koos B, Geis-Gerstorfer J, Li P, Spintzyk S. Effect of post-rinsing time on the mechanical strength and cytotoxicity of a 3D printed orthodontic splint material. Dent Mater 2021; 37:e314-e327. [PMID: 33610310 DOI: 10.1016/j.dental.2021.01.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 12/13/2020] [Accepted: 01/20/2021] [Indexed: 02/08/2023]
Abstract
OBJECTIVE Since the post-rinsing time is inconsistently recommended, this study aims to investigate the effect of post-rinsing time on the flexural strength and cytotoxicity of an stereolithographically (SLA) printed orthodontic splint material. METHODS SLA-printed specimens were ultrasonically rinsed with isopropanol (IPA) for 5 min, 12 min, 20 min, 30 min, 1 h, and 12 h, respectively. Surface characterization was conducted by scanning electron microscopy and roughness measurements. Flexural strength was evaluated using a three-point bending test. Cytotoxicity was determined by direct contact test and extract test. For both tests, cell viability (live/dead staining) and cell metabolic activity (CCK-8 assay) were evaluated. Additionally, water sorption and water solubility were tested to analyze the mass loss from immersion. RESULTS No apparent surface alterations could be detected on the samples post-rinsed for less than 1 h. In contrast, when the post-rinsing time was prolonged to 12 h, surface fissures could be observed. Flexural strength linearly decreased with increasing post-rinsing time. All post-processed specimens did not show an obvious cytotoxic effect. SIGNIFICANCE The removal of cytotoxic methacrylate monomers by post-rinsing with IPA could be achieved in 5 min. Extending post-rinsing time could not improve the cytocompatibility of the SLA-printed orthodontic splint material, and may result in a decrease in flexural strength.
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Affiliation(s)
- Yichen Xu
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; Department of Oral Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, Sichuan, China; University Hospital Tübingen, Section Medical Materials Science and Technology, Osianderstrasse 2-8, Tübingen 72076, Germany
| | - Alexander B Xepapadeas
- Department of Orthodontics, University Hospital Tübingen, Osianderstrasse 2-8, Tübingen 72076, Germany
| | - Bernd Koos
- Department of Orthodontics, University Hospital Tübingen, Osianderstrasse 2-8, Tübingen 72076, Germany
| | - Jürgen Geis-Gerstorfer
- University Hospital Tübingen, Section Medical Materials Science and Technology, Osianderstrasse 2-8, Tübingen 72076, Germany
| | - Ping Li
- University Hospital Tübingen, Section Medical Materials Science and Technology, Osianderstrasse 2-8, Tübingen 72076, Germany.
| | - Sebastian Spintzyk
- University Hospital Tübingen, Section Medical Materials Science and Technology, Osianderstrasse 2-8, Tübingen 72076, Germany
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Xu X, Awad A, Robles-Martinez P, Gaisford S, Goyanes A, Basit AW. Vat photopolymerization 3D printing for advanced drug delivery and medical device applications. J Control Release 2020; 329:743-757. [PMID: 33031881 DOI: 10.1016/j.jconrel.2020.10.008] [Citation(s) in RCA: 118] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/02/2020] [Accepted: 10/03/2020] [Indexed: 12/17/2022]
Abstract
Three-dimensional (3D) printing is transforming manufacturing paradigms within healthcare. Vat photopolymerization 3D printing technology combines the benefits of high resolution and favourable printing speed, offering a sophisticated approach to fabricate bespoke medical devices and drug delivery systems. Herein, an overview of the vat polymerization techniques, their unique applications in the fields of drug delivery and medical device fabrication, material examples and the advantages they provide within healthcare, is provided. The challenges and drawbacks presented by this technology are also discussed. It is forecast that the adoption of 3D printing could pave the way for a personalised health system, advancing from traditional treatments pathways towards digital healthcare.
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Affiliation(s)
- Xiaoyan Xu
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Atheer Awad
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Pamela Robles-Martinez
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Simon Gaisford
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK; FabRx Ltd., 3 Romney Road, Ashford, Kent TN24 0RW, UK
| | - Alvaro Goyanes
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK; FabRx Ltd., 3 Romney Road, Ashford, Kent TN24 0RW, UK; Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, I + D Farma (GI-1645), Facultad de Farmacia, and Health Research Institute of Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| | - Abdul W Basit
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK; FabRx Ltd., 3 Romney Road, Ashford, Kent TN24 0RW, UK.
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Alifui-Segbaya F, Bowman J, White AR, Varma S, Lieschke GJ, George R. Toxicological assessment of additively manufactured methacrylates for medical devices in dentistry. Acta Biomater 2018; 78:64-77. [PMID: 30099197 DOI: 10.1016/j.actbio.2018.08.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 06/28/2018] [Accepted: 08/07/2018] [Indexed: 12/11/2022]
Abstract
The paucity of information on the biological risks of photopolymers in additive manufacturing is a major challenge for the uptake of the technology in the construction of medical devices in dentistry. In this paper, the biocompatibility of methacrylates for denture bases, splints, retainers and surgical guides were evaluated using the innovative zebrafish embryo model, which is providing a high potential for toxicity profiling of photopolymers and has high genetic similarity to humans. Toxicological data obtained confirmed gradations of toxicity influenced by ethanol treatment, exposure scenarios and extraction vehicles. In direct exposure tests, juvenile fish exposed to non-treated methacrylates in ultrapure water showed accelerated toxicity endpoints compared to fish in transparent E3 medium. Similarly, toxic extracts induced mostly acute responses (embryonic mortality) in contrast to cumulative chronic (sublethal and teratogenic effects) in direct exposure. Methacrylates composed of >60% Ethoxylated bisphenol A dimethacrylate produced a relatively lower conversion rate in FTIR spectroscopy, but were safe in zebrafish bioassays after ethanol treatment. The study affirms that biocompatibility was influenced primarily by physico-chemical characteristics of the materials, which subsequently influenced their residual monomer content before and after immersion in ethanol. Given the precautionary implications of the study, we propose a 3-tiered approach i.e. using approved materials, apposite manufacturing parameters and post-processing techniques that together guarantee optimal results for medical devices. STATEMENT OF SIGNIFICANCE This study is timely and relevant since there is limited published literature that precisely describes the toxicological properties of additively manufactured methacrylates despite their increased popularity for medical devices. While it is generally accepted that the zebrafish excels as a model system for developmental toxicity, a further examination of its utility in this study using different protocols provides basis for its consideration and adoption at a crucial time when there is a lack of consensus regarding the most suited biological assessment methods for medical devices.
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Affiliation(s)
- Frank Alifui-Segbaya
- School of Dentistry and Oral Health, Griffith Health, Gold Coast Campus, Griffith University, QLD 4222, Australia.
| | - Jasper Bowman
- School of Environment and Science, Griffith Sciences, Nathan Campus, Griffith University, QLD 4111, Australia.
| | - Alan R White
- School of Environment and Science, Griffith Sciences, Nathan Campus, Griffith University, QLD 4111, Australia.
| | - Sony Varma
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria 3800, Australia.
| | - Graham J Lieschke
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria 3800, Australia.
| | - Roy George
- School of Dentistry and Oral Health, Griffith Health, Griffith University, Australia.
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Vaidyanathan TK, Vaidyanathan J, Arghavani D. Elastic, viscoelastic and viscoplastic contributions to compliance during deformation under stress in prosthodontic temporization materials. ACTA BIOMATERIALIA ODONTOLOGICA SCANDINAVICA 2017. [PMID: 28642920 PMCID: PMC5433204 DOI: 10.1080/23337931.2016.1219664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Purpose: The goal of this investigation was to characterize the compliance properties in selected polymers used for temporary (provisional crown and bridge) applications. Method: Polymethyl methacrylate (PMMA)- and polyethyl methacrylate (PEMA)-based JET and TRIM II were investigated along with two bisacryl composite resins (LUXATEMP and PROTEMP 3 GARANT). Rectangular samples of the resins were subjected to creep–recovery tests in a dynamic mechanical analyzer at and near the oral temperature (27 °C, 37 °C and 47 °C). The instantaneous (elastic), and time-dependent viscoelastic, and viscoplastic compliance profiles of the materials were determined and analyzed as a function of materials and temperature. Results: Highly significant (p = 0.0001) differences among means of elastic, viscoelastic and viscoplastic compliance values were found as a function of materials. TRIM II showed an order of magnitude higher viscoplastic deformation than the other three materials (LUXATEMP, PROTEMP 3 GARANT and JET). Conclusions: The results indicate that PEMA is susceptible to significantly greater elastic, viscoelastic, and more importantly to viscoplastic compliant behavior compared with bisacryl composite and PMMA provisional crown and bridge materials. This indicates high-dimensional instability and poor stiffness and resiliency in PEMA appliances vis-à-vis those of PMMA and bisacryl composites.
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Affiliation(s)
| | | | - David Arghavani
- Department of Cardiology and Comprehensive Care, New York University College of DentistryNew YorkNYUSA
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Vaidyanathan T, Vaidyanathan J, Manasse M. Analysis of stress relaxation in temporization materials in dentistry. Dent Mater 2014; 31:e55-62. [PMID: 25498989 DOI: 10.1016/j.dental.2014.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 11/04/2014] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Although temporization is intended as an interim step, complexity of individual treatment situations may demand medium to longer term use of temporary appliances in clinical practice. The durability and integrity of these restorations for continued use to meet the treatment demands is therefore an important clinical problem. The goal of this study was to evaluate the short to medium term stability of these materials under controlled loading to study their stress relaxation behavior. METHODS Acrylic resins (poly(methyl) and poly(ethyl) methacrylate) and bis-acryl composite resins were tested in vitro in this study. The stress decay data with time (under an applied constant strain) due to internal strain caused by molecular relaxation were systematically analyzed using important parameters derived from stress changes with time. RESULTS AND SIGNIFICANCE The results showed significant differences in the stress relaxation behavior between different materials which may have significant bearing on their durability in medium to longer term interim clinical applications. Poly(ethyl) methacrylate (PEMA) resins subjected to applied constant strain over a period of time showed large time dependent decay of applied stress, indicating very high internal molecular relaxation effects, relative to those of poly(methyl) methacrylate (PMMA) and bis-acryl composites. The results showed that PMMA and composite resins were superior in their ability to maintain constant strain without excessive dissipation of applied stress than PEMA resin. This suggests that internal strain caused by molecular relaxation events may lead to excessive dimensional instability in PEMA.
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Affiliation(s)
- Tritala Vaidyanathan
- Department of Restorative Dentistry, Rutgers School of Dental Medicine, Newark, NJ, USA.
| | | | - Maryse Manasse
- Department of Restorative Dentistry, Rutgers School of Dental Medicine, Newark, NJ, USA
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