1
|
Win PP, Moe OG, Chen DDS, Peng TY, Cheng JHC. A Comparative Analysis of Mechanical Properties of Polyetheretherketone (PEEK) vs. Standard Materials Used in Orthodontic Fixed Appliances: A Systematic Review. Polymers (Basel) 2024; 16:1271. [PMID: 38732740 PMCID: PMC11085924 DOI: 10.3390/polym16091271] [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: 04/15/2024] [Revised: 04/28/2024] [Accepted: 04/30/2024] [Indexed: 05/13/2024] Open
Abstract
Polyetheretherketone (PEEK), an organic thermoplastic polymer, has gained interest in dentistry due to its excellent mechanical strength, flexibility, and biocompatibility. Furthermore, the ability to utilize CAD/CAM in the fabrication of PEEK enhances accuracy, reliability, and efficiency while also saving time. Hence, several orthodontic studies have explored the utilization of PEEK in various applications, such as archwires, brackets, fixed lingual retainers, palatal expansion devices, transpalatal arches, Tübingen palatal plates, different types of space maintainers, mini-implant insertion guides, and more. However, a complete systematic review of the available data comparing the performance of PEEK with traditional orthodontic materials has not yet been conducted. Therefore, this systematic review seeks to assess if PEEK material meets the required mechanical criteria to serve as an alternative to conventional orthodontic appliances. To ensure clarity and precision, this review will specifically concentrate on fixed appliances. This systemic review followed the PRISMA guidelines and utilized databases including PubMed/MEDLINE, Embase, Springer, Web of Science, and Wiley. Searches were restricted to English language articles from January 2013 to February 2024. Keywords such as "Polyetheretherketone" or "PEEK" and "Orthodontic" or "Orthodontic device" or "Orthodontic materials" were employed across all databases. Nine studies were incorporated, covering orthodontic archwires, brackets, and fixed lingual retainers. Based on the reviewed literature, PEEK demonstrates promising potential in orthodontic fixed appliances, offering advantages in force delivery, friction reduction, and aesthetic appeal. Further research is needed to fully explore its capabilities and optimize its application in clinical practice.
Collapse
Affiliation(s)
- Pyi Phyo Win
- School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan; (P.P.W.); (D.D.-S.C.)
- Division of Orthodontics, Department of Dentistry, Taipei Medical University Hospital, Taipei 11031, Taiwan
| | - Oak Gar Moe
- School of Dentistry, University of Michigan, Ann Arbor, MI 48104, USA;
| | - Daniel De-Shing Chen
- School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan; (P.P.W.); (D.D.-S.C.)
- Division of Orthodontics, Department of Dentistry, Taipei Medical University Hospital, Taipei 11031, Taiwan
| | - Tzu-Yu Peng
- School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan; (P.P.W.); (D.D.-S.C.)
| | - Johnson Hsin-Chung Cheng
- School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan; (P.P.W.); (D.D.-S.C.)
- Division of Orthodontics, Department of Dentistry, Taipei Medical University Hospital, Taipei 11031, Taiwan
| |
Collapse
|
2
|
Abbas K, Hedwig L, Balc N, Bremen S. Advanced FFF of PEEK: Infill Strategies and Material Characteristics for Rapid Tooling. Polymers (Basel) 2023; 15:4293. [PMID: 37959972 PMCID: PMC10650530 DOI: 10.3390/polym15214293] [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: 09/28/2023] [Revised: 10/26/2023] [Accepted: 10/30/2023] [Indexed: 11/15/2023] Open
Abstract
Traditional vulcanization mold manufacturing is complex, costly, and under pressure due to shorter product lifecycles and diverse variations. Additive manufacturing using Fused Filament Fabrication and high-performance polymers like PEEK offer a promising future in this industry. This study assesses the compressive strength of various infill structures (honeycomb, grid, triangle, cubic, and gyroid) when considering two distinct build directions (Z, XY) to enhance PEEK's economic and resource efficiency in rapid tooling. A comparison with PETG samples shows the behavior of the infill strategies. Additionally, a proof of concept illustrates the application of a PEEK mold in vulcanization. A peak compressive strength of 135.6 MPa was attained in specimens that were 100% solid and subjected to thermal post-treatment. This corresponds to a 20% strength improvement in the Z direction. In terms of time and mechanical properties, the anisotropic grid and isotropic cubic infill have emerged for use in rapid tooling. Furthermore, the study highlights that reducing the layer thickness from 0.15 mm to 0.1 mm can result in a 15% strength increase. The study unveils the successful utilization of a room-temperature FFF-printed PEEK mold in vulcanization injection molding. The parameters and infill strategies identified in this research enable the resource-efficient FFF printing of PEEK without compromising its strength properties. Using PEEK in rapid tooling allows a cost reduction of up to 70% in tool production.
Collapse
Affiliation(s)
- Karim Abbas
- Department of Mechanical Engineering, University of Applied Sciences Aachen, 52064 Aachen, Germany; (L.H.); (S.B.)
| | - Lukas Hedwig
- Department of Mechanical Engineering, University of Applied Sciences Aachen, 52064 Aachen, Germany; (L.H.); (S.B.)
| | - Nicolae Balc
- Department of Manufacturing Engineering, Technical University of Cluj-Napoca, 400641 Cluj-Napoca, Romania;
| | - Sebastian Bremen
- Department of Mechanical Engineering, University of Applied Sciences Aachen, 52064 Aachen, Germany; (L.H.); (S.B.)
| |
Collapse
|
3
|
Smith JA, Petersmann S, Arbeiter F, Schäfer U. Optimization and manufacture of polyetheretherketone patient specific cranial implants by material extrusion - A clinical perspective. J Mech Behav Biomed Mater 2023; 144:105965. [PMID: 37343357 DOI: 10.1016/j.jmbbm.2023.105965] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 06/01/2023] [Accepted: 06/06/2023] [Indexed: 06/23/2023]
Abstract
Polyetheretherketone (PEEK) is a high performing thermoplastic that has established itself as a 'gold-standard' material for cranial reconstruction. Traditionally, milled PEEK patient specific cranial implants (PSCIs) exhibit uniform levels of smoothness (excusing suture/drainage holes) to the touch (<1 μm) and homogenous coloration throughout. They also demonstrate predictable and repeatable levels of mechanical performance, as they are machined from isotropic material blocks. The combination of such factors inspires confidence from the surgeon and in turn, approval for implantation. However, manufacturing lead-times and affiliated costs to fabricate a PSCI are high. To simplify their production and reduce expenditure, hospitals are exploring the production of in-house PEEK PSCIs by material extrusion-based additive manufacturing. From a geometrical and morphological perspective, such implants have been produced with good-to-satisfactory clinical results. However, lack of clinical adoption persists. To determine the reasoning behind this, it was necessary to assess the benefits and limitations of current printed PEEK PSCIs in order to establish the status quo. Afterwards, a review on individual PEEK printing variables was performed in order to identify a combination of parameters that could enhance the aesthetics and performance of the PSCIs to that of milled implants/cranial bone. The findings from this review could be used as a baseline to help standardize the production of PEEK PSCIs by material extrusion in the hospital.
Collapse
Affiliation(s)
- James A Smith
- Research Unit Experimental Neurotraumatology, Department of Neurosurgery, Medical University of Graz, Auenbruggerplatz 2(9), 8036, Graz, Austria.
| | - Sandra Petersmann
- Materials Science and Testing of Polymers, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700, Leoben, Austria
| | - Florian Arbeiter
- Materials Science and Testing of Polymers, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700, Leoben, Austria
| | - Ute Schäfer
- Research Unit Experimental Neurotraumatology, Department of Neurosurgery, Medical University of Graz, Auenbruggerplatz 2(9), 8036, Graz, Austria; BioTechMed-Graz, Graz, Austria
| |
Collapse
|
4
|
Wang YN, Ren YN, Han J, Chen C, Sun X, Di MY, Dou YM, Ma XL, Wang Z, Du CF, Yang Q. Biomechanical effects of screws of different materials on vertebra-pediculoplasty: a finite element study. Front Bioeng Biotechnol 2023; 11:1225925. [PMID: 37456721 PMCID: PMC10340523 DOI: 10.3389/fbioe.2023.1225925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 06/21/2023] [Indexed: 07/18/2023] Open
Abstract
Background: The effects of cannulated screws made of polyetheretherketone (PEEK) on the biomechanical properties of the vertebral body during vertebra-pediculoplasty remain unclear. This study aimed to investigate whether PEEK screws have the potential to replace titanium alloy screws. Methods: The surgical model of two different materials of screws was constructed using the finite element method. The biomechanical effects of the two models on the vertebral body under different working conditions were compared. Results: ① The peak von Mises stress of PEEK screws was significantly lower than that of titanium screws, with a reduction ranging from 52% to 80%. ② The von Mises stress values for the injured T12 spine were similar for both materials. Additionally, the segmental range of motion and intervertebral disc pressure showed no significant difference between the two materials. Conclusion: PEEK screws demonstrated advantages over titanium screws and may serve as a viable alternative for screw materials in vertebra-pediculoplasty.
Collapse
Affiliation(s)
- Yan-Ni Wang
- Department of Spine Surgery, Tianjin Hospital, Tianjin University, Tianjin, China
| | - Ya-Nan Ren
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China
- National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Jun Han
- Department of Spine Surgery, Tianjin Hospital, Tianjin University, Tianjin, China
| | - Chao Chen
- Department of Spine Surgery, Tianjin Hospital, Tianjin University, Tianjin, China
| | - Xun Sun
- Department of Spine Surgery, Tianjin Hospital, Tianjin University, Tianjin, China
| | - Ming-Yuan Di
- Department of Spine Surgery, Tianjin Hospital, Tianjin University, Tianjin, China
| | - Yi-Ming Dou
- Department of Spine Surgery, Tianjin Hospital, Tianjin University, Tianjin, China
| | - Xin-Long Ma
- Department of Spine Surgery, Tianjin Hospital, Tianjin University, Tianjin, China
| | - Zheng Wang
- Department of Orthopaedics, Chinese People’s Liberation Army General Hospital, Beijing, China
| | - Cheng-Fei Du
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China
- National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Qiang Yang
- Department of Spine Surgery, Tianjin Hospital, Tianjin University, Tianjin, China
| |
Collapse
|
5
|
Czyżewski W, Jachimczyk J, Hoffman Z, Szymoniuk M, Litak J, Maciejewski M, Kura K, Rola R, Torres K. Low-Cost Cranioplasty—A Systematic Review of 3D Printing in Medicine. MATERIALS 2022; 15:ma15144731. [PMID: 35888198 PMCID: PMC9315853 DOI: 10.3390/ma15144731] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/20/2022] [Accepted: 07/02/2022] [Indexed: 11/22/2022]
Abstract
The high cost of biofabricated titanium mesh plates can make them out of reach for hospitals in low-income countries. To increase the availability of cranioplasty, the authors of this work investigated the production of polymer-based endoprostheses. Recently, cheap, popular desktop 3D printers have generated sufficient opportunities to provide patients with on-demand and on-site help. This study also examines the technologies of 3D printing, including SLM, SLS, FFF, DLP, and SLA. The authors focused their interest on the materials in fabrication, which include PLA, ABS, PET-G, PEEK, and PMMA. Three-dimensional printed prostheses are modeled using widely available CAD software with the help of patient-specific DICOM files. Even though the topic is insufficiently researched, it can be perceived as a relatively safe procedure with a minimal complication rate. There have also been some initial studies on the costs and legal regulations. Early case studies provide information on dozens of patients living with self-made prostheses and who are experiencing significant improvements in their quality of life. Budget 3D-printed endoprostheses are reliable and are reported to be significantly cheaper than the popular counterparts manufactured from polypropylene polyester.
Collapse
Affiliation(s)
- Wojciech Czyżewski
- Department of Didactics and Medical Simulation, Medical University of Lublin, 20-093 Lublin, Poland; (W.C.); (K.T.)
- Department of Neurosurgery and Pediatric Neurosurgery in Lublin, 20-090 Lublin, Poland; (J.L.); (K.K.); (R.R.)
| | - Jakub Jachimczyk
- Student Scientific Society, Medical University of Lublin, 20-059 Lublin, Poland;
| | - Zofia Hoffman
- Student Scientific Society, Medical University of Lublin, 20-059 Lublin, Poland;
- Correspondence:
| | - Michał Szymoniuk
- Student Scientific Association of Neurosurgery, Department of Neurosurgery and Pediatric Neurosurgery, Medical University of Lublin, 20-090 Lublin, Poland;
| | - Jakub Litak
- Department of Neurosurgery and Pediatric Neurosurgery in Lublin, 20-090 Lublin, Poland; (J.L.); (K.K.); (R.R.)
- Department of Clinical Immunology, Medical University of Lublin, 20-093 Lublin, Poland
| | - Marcin Maciejewski
- Department of Electronics and Information Technology, Faculty of Electrical Engineering and Computer Science, Lublin University of Technology, 20-618 Lublin, Poland;
| | - Krzysztof Kura
- Department of Neurosurgery and Pediatric Neurosurgery in Lublin, 20-090 Lublin, Poland; (J.L.); (K.K.); (R.R.)
| | - Radosław Rola
- Department of Neurosurgery and Pediatric Neurosurgery in Lublin, 20-090 Lublin, Poland; (J.L.); (K.K.); (R.R.)
| | - Kamil Torres
- Department of Didactics and Medical Simulation, Medical University of Lublin, 20-093 Lublin, Poland; (W.C.); (K.T.)
| |
Collapse
|
6
|
Jureczko M, Mrówka M. Multiobjective Optimization of Composite Wind Turbine Blade. MATERIALS 2022; 15:ma15134649. [PMID: 35806770 PMCID: PMC9267708 DOI: 10.3390/ma15134649] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 02/04/2023]
Abstract
When designing a wind turbine, the main objective is to generate maximum effective power with the lowest possible production costs. The power of a wind turbine depends primarily on the aerodynamic properties of its blades. Moreover, the cost of making a blade for a wind turbine, and therefore also for the entire wind turbine, depends on the materials used for its production. Therefore, wind turbine blades are the most studied element of a wind turbine. By selecting the optimal material and geometric properties of the wind turbine blade, it is possible to reduce the costs of making the entire wind turbine. These rationales led the authors to investigate composite wind turbine blades. A two-criteria optimization task was formulated, which allowed for the simultaneous consideration of two criteria: minimizing the mass and minimizing the vertical deflection of the wind turbine blade. Geometric properties of the blade, influencing the considered criteria, were assumed as decision variables. The weighted sum method was used. The results obtained allowed us to determine the optimal geometric and material properties of a wind turbine blade.
Collapse
|
7
|
Kosicka E, Borowiec M, Kowalczuk M, Krzyzak A. Dynamic Behavior of Aviation Polymer Composites at Various Weight Fractions of Physical Modifier. MATERIALS 2021; 14:ma14226897. [PMID: 34832296 PMCID: PMC8618136 DOI: 10.3390/ma14226897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 11/16/2022]
Abstract
The aim of this study was to determine the effect of a selected physical modifier with different granularity and mass percentage on the dynamics of aerospace polymer composites. The tests were carried out on samples made of certified aerospace materials used, among other purposes, for the manufacture of aircraft skin components. The hybrid composites were prepared from L285 resin, H286 hardener, GG 280T carbon fabric in twill 2/2 and alumina (Al2O3, designated as EA in this work). The manufactured composites contained alumina with grain sizes of F220, F240, F280, F320 and F360. The mass proportion of the modifier in the tested samples was 5% and 15%. The tested specimens, as cantilever beams fixed unilaterally, were subjected to kinematic excitation with defined parameters of amplitude and frequency excitation in the basic resonance zone of the structure. The results, obtained as dynamic responses, are presented in the form of amplitude-frequency characteristics. These relationships clearly indicate the variable nature of composite materials due to modifier density and grain size. The novelty of this study is the investigation of the influence of the alumina properties on system dynamics responses.
Collapse
Affiliation(s)
- Ewelina Kosicka
- Faculty of Mechanical Engineering, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland; (M.B.); (M.K.)
- Correspondence: ; Tel.: +48-815384240
| | - Marek Borowiec
- Faculty of Mechanical Engineering, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland; (M.B.); (M.K.)
| | - Marcin Kowalczuk
- Faculty of Mechanical Engineering, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland; (M.B.); (M.K.)
| | - Aneta Krzyzak
- Faculty of Aeronautics, Military University of Aviation, Dywizjonu 303 No. 25, 08-521 Deblin, Poland;
| |
Collapse
|
8
|
Zhang J, Yi Y, Wang C, Ding L, Wang R, Wu G. Effect of Acid-Etching Duration on the Adhesive Performance of Printed Polyetheretherketone to Veneering Resin. Polymers (Basel) 2021; 13:polym13203509. [PMID: 34685268 PMCID: PMC8538367 DOI: 10.3390/polym13203509] [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: 09/05/2021] [Revised: 10/05/2021] [Accepted: 10/09/2021] [Indexed: 02/07/2023] Open
Abstract
Three-dimensional printing polyetheretherketone (PEEK) provides a new choice for dental prostheses, while its appropriate bonding procedure and adhesive performance are still unclear. This study aimed to investigate the adhesive performance of printed polyetheretherketone (PEEK) after acid etching to veneering resin. In total, 182 PEEK specimens (including 91 printed and 91 milled specimens) were distributed to 14 subgroups (n = 13/subgroup), according to the manufacturing process and surface treatment. The specimens were polished and etched with sulfuric acid for 0, 5, 30, 60, 90, 120, and 300 s, respectively. Two specimens in each subgroup were observed under a scanning electron microscope (SEM) for surface and cross-section morphology separately. Then, the specimens were treated with a bonding primer, and one specimen in each subgroup was prepared for cross-sectional observation under SEM. The residual 10 specimens of each subgroup bonded with veneering resin were tested with the shear bond strength tests (SBS) and failure modes analysis. Statistical analysis was performed by one-way ANOVA followed by the SNK-q post hoc test (p < 0.05). The etched pores on the PEEK surface were broadened and deepened under SEM over time. Printed PEEK etched for 30 s obtained the best SBS-to-veneering-resin ratio (27.90 ± 3.48 MPa) among the printed subgroups (p < 0.05) and had no statistical differences compared with milled PEEK etched for 30 s. The SBS of the milled subgroups etched from 5 to 120 s were over 29 MPa without significant between-group statistical differences. Hence, printed PEEK can be coarsened effectively by 30 s of sulfuric acid etching. The adhesion efficacy of printed PEEK to veneering resin was qualified for clinical requirements of polymer-based fixed dentures.
Collapse
Affiliation(s)
- Jiaqi Zhang
- Department of Prosthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210000, China; (J.Z.); (Y.Y.); (C.W.); (L.D.); (R.W.)
| | - Yingjie Yi
- Department of Prosthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210000, China; (J.Z.); (Y.Y.); (C.W.); (L.D.); (R.W.)
| | - Chenwei Wang
- Department of Prosthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210000, China; (J.Z.); (Y.Y.); (C.W.); (L.D.); (R.W.)
| | - Ling Ding
- Department of Prosthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210000, China; (J.Z.); (Y.Y.); (C.W.); (L.D.); (R.W.)
| | - Ruijin Wang
- Department of Prosthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210000, China; (J.Z.); (Y.Y.); (C.W.); (L.D.); (R.W.)
| | - Guofeng Wu
- Department of Prosthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210000, China; (J.Z.); (Y.Y.); (C.W.); (L.D.); (R.W.)
- Digital Engineering Center of Stomatology and Department of Prosthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing 210000, China
- Correspondence:
| |
Collapse
|
9
|
Influence of the Halloysite Nanotube (HNT) Addition on Selected Mechanical and Biological Properties of Thermoplastic Polyurethane. MATERIALS 2021; 14:ma14133625. [PMID: 34209626 PMCID: PMC8269716 DOI: 10.3390/ma14133625] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/10/2021] [Accepted: 06/18/2021] [Indexed: 11/16/2022]
Abstract
Halloysite nanotube (HNT) additions to the thermoplastic polyurethane (TPU) system were thoroughly evaluated in this study. The resultant composites have been designed for future personalized intervertebral disc implant applications, which requires additional technology to obtain the appropriate geometry unique to each patient. These requirements can be fulfilled using 3D printing. In this work, a technology was developed to produce filaments for fused deposition modeling (FDM). Nanocomposites were prepared using variable HNT content (1, 2, and 3 wt.%). The nanostructure of the resultant composites was confirmed using scanning transmission electron microscopy (STEM). Mechanical tests were used to measure the tensile modulus, stress, and elongation the composites and TPU matrix. Nanocomposites with 2% HNT content were able to withstand 26% increased stress and 50% increased elongation compared to pure TPU before fracturing in addition to a 13% reduction in the friction coefficient. A MTT cytotoxicity assay confirmed the cytotoxicity of all tested materials against human epidermal keratinocyte cells (HaCaT).
Collapse
|