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Nakornnoi T, Bunjerdjin P, Santiwong P, Sipiyaruk K, Neoh SP, Chintavalakorn R. The Influence of Thickness on the Mechanical Behaviors of 3D Printing Resins for Orthodontic Retainers. Int J Biomater 2024; 2024:7398478. [PMID: 38957572 PMCID: PMC11219205 DOI: 10.1155/2024/7398478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 04/12/2024] [Accepted: 06/13/2024] [Indexed: 07/04/2024] Open
Abstract
This study aimed to evaluate the mechanical behaviors of thermoformed and 3D-printed retainers with different thicknesses. Thermoformed retainers (Duran) and 3D-printed retainers (Dental LT Clear V2 and NextDent Ortho Flex) were fabricated at thicknesses of 0.5, 0.75, and 1 mm. Five samples of each material were subjected to compression, tensile, and flexural testing with the universal testing machine (Instron Ltd., Buckinghamshire, England). The results revealed that the mechanical behaviors were significantly influenced by thickness in each type of material. The increased thickness tended to increase strength and modulus in all three tests. However, Dental LT Clear V2 and Duran showed that flexural strength and modulus were inversely related to thickness. The compressive test revealed significantly greater compressive resistance in 3D-printed groups, except for the NextDent Ortho Flex at 0.5 mm. The tensile test showed that Dental LT Clear V2 at all thicknesses demonstrated significantly higher tensile strength and modulus, while NextDent Ortho Flex was significantly lowest at any thickness in tensile and flexural properties. In conclusion, the thickness significantly influenced the mechanical behaviors of the 3D-printed retainers. The 0.75 mm thickness of Dental LT Clear V2 could be considered as an alternative to fabricated retainers due to its similar mechanical properties compared with the thermoformed material.
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Affiliation(s)
- Theerasak Nakornnoi
- Department of OrthodonticsFaculty of DentistryMahidol University, Bangkok, Thailand
| | | | - Peerapong Santiwong
- Department of OrthodonticsFaculty of DentistryMahidol University, Bangkok, Thailand
| | - Kawin Sipiyaruk
- Department of OrthodonticsFaculty of DentistryMahidol University, Bangkok, Thailand
| | - Siew Peng Neoh
- Department of OrthodonticsFaculty of DentistryMahidol University, Bangkok, Thailand
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Barile C, Cianci C, Paramsamy Kannan V, Pappalettera G, Pappalettere C, Casavola C, Suriano C, Ciavarella D. Thermoplastic clear dental aligners under cyclic compression loading: A mechanical performance analysis using acoustic emission technique. J Mech Behav Biomed Mater 2024; 152:106451. [PMID: 38310814 DOI: 10.1016/j.jmbbm.2024.106451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/26/2024] [Accepted: 01/30/2024] [Indexed: 02/06/2024]
Abstract
The objective of this work is to analyse the performance of clear aligners made of thermoplastic materials. Within this framework, the damage evolution stages and damage states of the aligners at different cycles of the compressive loading are evaluated using the Acoustic Emission (AE) technique. Three different clear aligner systems were prepared: thermoformed PET-g (polyethylene terephthalate glycol) and PU (polyurethane), and additively manufactured PU. Cyclic compression tests are performed to simulate 22500 swallows. The mechanical results show that the energy absorbed by the thermoformed PET-g aligner remains stable around 4 Nmm throughout the test. Although the PU-based aligners show a higher energy absorption of about 7 Nmm during the initial phase of the cyclic loading, this gradually decreases after 12500 cycles. The time-domain based, and frequency-based parameters of the stress wave acoustic signals generated by the aligners under compression loading are used to identify the damage evolution stages. The machine learning-based AE results reveal the initiation and termination of the different damage states in the aligners and the frequency-based results distinguish the different damage sources. Finally, the microscopy results validated the damage occurrences in the aligners identified by the AE results. The mechanical test results indicate that the thermoformed PET-g has the potential to match the performance and requirements of the dentistry of the popular Invisalign (additively manufactured PU). The AE results have the potential to identify at which cycles the aligners may start losing their functionality.
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Affiliation(s)
- Claudia Barile
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
| | - Claudia Cianci
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
| | | | - Giovanni Pappalettera
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy.
| | - Carmine Pappalettere
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
| | - Caterina Casavola
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Bari, Italy
| | - Carmela Suriano
- Dipartimento di Medicina Sperimentale e Clinica, Università di Foggia, Foggia, Italy
| | - Domenico Ciavarella
- Dipartimento di Medicina Sperimentale e Clinica, Università di Foggia, Foggia, Italy
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Jin C, Gray AR, Brunton PA, Farella M, Mei L. Effect of carbamide peroxide on biomechanical properties of vacuum-formed retainers: A split-mouth randomized controlled trial. J Dent 2024; 143:104902. [PMID: 38432352 DOI: 10.1016/j.jdent.2024.104902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/22/2024] [Accepted: 02/26/2024] [Indexed: 03/05/2024] Open
Abstract
OBJECTIVE To investigate the effect of tooth whitening on biomechanical properties of vacuum-formed retainers (VFRs). METHODS Using a split-mouth, randomised controlled trial design, thirty participants were randomly allocated to receive whitening on either the upper or the lower arch, using 10 % carbamide peroxide for two weeks. Biomechanical properties such as hardness, tensile strength, and surface roughness were assessed two weeks after whitening was completed. RESULTS Tensile strength of the whitening arch (mean ± SD: 40.93 ± 3.96 MPa) was significantly lower than that of the control (47.40 ± 5.03 MPa) (difference 6.47 MPa, 95 % CI 4.51 - 8.42, p < 0.001). Hardness and internal roughness of the whitening arch (VHN = 14.63 ± 2.29 N/mm2 and Ra = 1.33 ± 0.35 µm, respectively) were significantly greater than those of the control (12.22 ± 1.86 N/mm2 and 0.96 ± 0.29 µm, respectively) (differences 2.41 N/mm2, 95 % CI 1.56 - 3.25, p < 0.001 and 0.37 µm, 95 % CI 0.23 - 0.51, p < 0.001, respectively). The whitening arch showed greater tooth colour change (ΔE = 6.00 ± 3.32) than the control (ΔE = 2.50 ± 1.70) (difference = 3.50, 95 % CI 2.43 - 4.56, p < 0.001). CONCLUSIONS Based on this short-term study, marked tooth colour change was achieved by whitening with VFRs as the whitening trays, but this changed the VFRs' biomechanical properties, including a decrease in tensile strength and an increase in hardness and internal roughness. CLINICAL SIGNIFICANCE The application of carbamide peroxide in VFRs may compromise their mechanical properties.
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Affiliation(s)
- Carrol Jin
- Discipline of Orthodontics, Department of Oral Science, Faculty of Dentistry, University of Otago, 310 Great King Street, Dunedin 9016, New Zealand
| | - Andrew R Gray
- University of Otago, Biostatistics Centre, Division of Health Sciences, 310 Great King Street, Dunedin 9016, New Zealand
| | | | - Mauro Farella
- Discipline of Orthodontics, Department of Oral Science, Faculty of Dentistry, University of Otago, 310 Great King Street, Dunedin, New Zealand; Department of Surgical Sciences, University of Cagliari, Italy
| | - Li Mei
- Discipline of Orthodontics, Department of Oral Science, Faculty of Dentistry, University of Otago, 310 Great King Street, Dunedin 9016, New Zealand.
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Atta I, Bourauel C, Alkabani Y, Mohamed N, Kimbe H, Alhotan A, Ghoneima A, Elshazly T. Physiochemical and mechanical characterisation of orthodontic 3D printed aligner material made of shape memory polymers (4D aligner material). J Mech Behav Biomed Mater 2024; 150:106337. [PMID: 38154364 DOI: 10.1016/j.jmbbm.2023.106337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/14/2023] [Accepted: 12/16/2023] [Indexed: 12/30/2023]
Abstract
OBJECTIVES To conduct a physiochemical and mechanical material analysis on 3D printed shape-memory aligners in comparison to thermoformed aligners. MATERIALS AND METHODS Four materials were examined, including three thermoformed materials: CA Pro (CP), Zendura A (ZA), Zendura FLX (ZF), and one 3D printed material: Tera Harz (TC-85). Rectangular strips measuring 50 × 10 × 0.5 mm were produced from each material. Five tests were conducted, including differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), shape recovery tests, three-points bending (3 PB), and Vickers surface microhardness (VH). RESULTS DSC recorded glass transition temperatures (Tg) at 79.9 °C for CP, 92.2 °C for ZA, 107.1 °C for ZF, and 42.3 °C for TC-85. In DMA analysis at 20-45 °C, a prominent decrease in storage modulus was observed, exclusively for TC-85, as the temperature increased. Notably, within the temperature range of 30-45 °C, TC-85 exhibited substantial shape recovery after 10 min, reaching up to 86.1 %, while thermoformed materials showed minimal recovery (1.5-2.9 %). In 3 PB test (at 30, 37, 45 °C), ZA demonstrated the highest force at 2 mm bending, while TC-85 exhibited the lowest. Regarding VH at room temperature, there was a significant decrease for both ZA and ZF after thermoforming. ZA had the highest hardness, followed by ZF and TC-85, with CP showing the lowest values. CONCLUSIONS TC-85 demonstrates exceptional shape memory at oral temperature, improving adaptation, reducing force decay, and enabling, together with its higher flexibility, extensive tooth movement per step. Additionally, it maintains microhardness similar to thermoformed sheets, ensuring the durability and effectiveness of dental aligners. CLINICAL RELEVANCE The 3D printed aligner material with shape memory characteristics (4D aligner) has revolutionized the orthodontic aligner field. It showed mechanical properties more suitable for orthodontic treatment than thermoforming materials. Additionally, it offers enhanced control over aligner design and thickness, while optimizing the overall workflow. It also minimizes material wastage, and reduces production expenses.
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Affiliation(s)
- Islam Atta
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany
| | | | - Yasmine Alkabani
- Restorative and Dental Materials Department, National Research Centre, Giza, Egypt
| | | | - Hoon Kimbe
- Research Institute of Agriculture and Life Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Abdulaziz Alhotan
- Department of Dental Health, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Ahmed Ghoneima
- Department of Orthodontics and Pediatric Dentistry, Hamdan Bin Mohammed College of Dental Medicine (HBMCDM), Mohammed Bin Rashid University of Medicine and Health Sciences (MBRU), Dubai, United Arab Emirates
| | - Tarek Elshazly
- Oral Technology, Dental School, University Hospital Bonn, Bonn, Germany; Department of Orthodontics and Pediatric Dentistry, Hamdan Bin Mohammed College of Dental Medicine (HBMCDM), Mohammed Bin Rashid University of Medicine and Health Sciences (MBRU), Dubai, United Arab Emirates.
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Viana G, Virji I, Susarchick L, Allareddy V, Lown S, Gruber M, Lukic H, Megremis S, Atsawasuwan P. Comparison of light transmittance and color changes between polyurethane and copolyester retainer materials after staining and destaining. BMC Oral Health 2024; 24:144. [PMID: 38297268 PMCID: PMC10829172 DOI: 10.1186/s12903-024-03887-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 01/11/2024] [Indexed: 02/02/2024] Open
Abstract
BACKGROUND Retainers are the only effective approach to prevent orthodontic relapse. The aim of this study was to compare the changes in color and light-transmittance of rough and smooth thermoformed polyurethane and copolymer retainer samples after staining in different solutions and destaining with different approaches. METHODS Four hundred copolyester (Essix® ACE) and 400 polyurethane (Zendura®) samples with different surface textures, smooth and rough, were stained in 4 different solutions (n = 100 per solution) over 28 days. Each of the four groups of 100 stained samples of each material was subdivided into 5 groups of 20 samples and subjected to different destaining solutions. Light transmittance and color changes were evaluated using a spectrometer and a spectrophotometer. Mean differences were compared using a two-way analysis of variance (ANOVA) and posthoc multiple comparison tests at P = 0.05. RESULTS No significant differences in light transmittance were found between both untreated materials. Both materials were stained in a similar fashion and showed no significant differences between two materials after staining. Coffee and tea stained both materials more significantly than wine, but there was a significant difference of changes of color and light transmittance between rough and smooth surfaces during the destaining in coffee- and tea-stained samples of copolyester material. All destaining solutions were effective at removing all stains on the samples. The surface roughness of the material plays a significant role in the ability of the materials to be destained, demonstrating a more significant greater effect on cleaning rough samples for improvements in light-transmittance and greater changes in color. CONCLUSIONS This study concluded that the surface of materials plays a significant role in the material destaining and staining. In addition, the different polymers used for retainer fabrication exhibited different responses during the destaining process depending on types of stains.
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Affiliation(s)
- Grace Viana
- Department of Orthodontics, University of Illinois Chicago, Chicago, IL, 60612, USA
| | - Insia Virji
- Department of Orthodontics, University of Illinois Chicago, Chicago, IL, 60612, USA
| | - Laurie Susarchick
- Department of Orthodontics, University of Illinois Chicago, Chicago, IL, 60612, USA
| | | | - Sullivan Lown
- Department of Orthodontics, University of Illinois Chicago, Chicago, IL, 60612, USA
| | - Max Gruber
- Dental Materials & Devices Research - American Dental Association, Chicago, IL, 60610, USA
| | - Henry Lukic
- Dental Materials & Devices Research - American Dental Association, Chicago, IL, 60610, USA
| | - Spiro Megremis
- Dental Materials & Devices Research - American Dental Association, Chicago, IL, 60610, USA
| | - Phimon Atsawasuwan
- Department of Orthodontics, University of Illinois Chicago, Chicago, IL, 60612, USA.
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Aldweesh AH, Al-Maflehi NS, AlGhizzi M, AlShayea E, Albarakati SF. Comparison of mechanical properties and color stability of various vacuum-formed orthodontic retainers: An in vitro study. Saudi Dent J 2023; 35:953-959. [PMID: 38107045 PMCID: PMC10724479 DOI: 10.1016/j.sdentj.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/30/2023] [Accepted: 09/04/2023] [Indexed: 12/19/2023] Open
Abstract
Vacuum-formed retainer (VFR) is the most used retainer due to its higher aesthetic properties and lower cost, their mechanical properties of are important in determining the stability and long-term use of appliances made out of them. AIM This study aimed to evaluate and compare the flexural modulus, surface hardness, and color stability of three different VFR materials. METHODS Three different VFR materials, namely Duran, Keystone, and Zendura, of 1 mm thickness, were tested after thermoforming for flexural modulus, hardness, and color stability. They were formed over a stainless-steel model of 12 mm diameter and 6 mm height. RESULTS There were significant statistical differences (p = 0.000) in the flexural modulus and hardness of the three materials. Regarding color stability, Zendura exhibited significantly higher ΔE* values than Keystone and Duran (p < 0.05). CONCLUSIONS Zendura had the highest flexural modulus and hardness compared with Duran and Keystone; however, it is more susceptible to color change compared to the other tested materials.
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Affiliation(s)
- Aljazi H. Aldweesh
- Division of Orthodontics, Department of Pediatric Dentistry and Orthodontics, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
| | - Nassr S. Al-Maflehi
- Periodontics and Community Dentistry, College of Dentistry, King Saud University, Saudi Arabia
| | | | - Eman AlShayea
- Division of Orthodontics, Department of Pediatric Dentistry and Orthodontics, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
| | - Sahar F. Albarakati
- Division of Orthodontics, Department of Pediatric Dentistry and Orthodontics, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
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Šimunović L, Jurela A, Sudarević K, Bačić I, Meštrović S. Differential Stability of One-layer and Three-layer Orthodontic Aligner Blends under Thermocycling: Implications for Clinical Durability. Acta Stomatol Croat 2023; 57:286-299. [PMID: 38283309 PMCID: PMC10812913 DOI: 10.15644/asc57/4/1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 12/01/2023] [Indexed: 01/30/2024] Open
Abstract
Objectives To optimize the therapeutic usefulness of aligners, it is crucial to understand how their mechanical properties alter with time. Materials and methods Specimens from four different brands, including Duran+, CA® Pro, Zendura A, and Zendura FLX, were produced for material testing of thermoplastic orthodontic aligners (TOA) using dimensions measuring 4mm x 10mm. Each brand's 24 samples were split into three groups as follows: G1 being thermoformed, G2 being thermoformed and underwent 500 thermocycles (simulating 7 days), and G3 being thermoformed and underwent 1000 thermocycles (simulating 14 days). Surface roughness, modulus of elasticity in bending, and spectrophotometry were used to assess the effect of aging on TOAs. Results After 1000 thermocycles, Duran+ had the highest modulus of elasticity and differed statistically from all other groups. The intragroup comparison showed that only Duran+'s elastic modulus significantly changed after 1000 thermocycles in comparison with the control group. Surface roughness values (Ra), did not statistically differ among brands or thermocycling group measures. The change in chemical properties was not significant in any brand. Conclusion One-layer PETG (Duran+) failed to demonstrate stability after in vitro aging, thus suggesting that clinicians should be aware of the change in mechanical properties when using one-layer PETG (Duran +) in a 2 weeks regime.
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Affiliation(s)
- Luka Šimunović
- Department of Orthodontics, School of Dental Medicine, University of Zagreb, Gundulićeva 5, 10000 Zagreb, Croatia
| | | | | | - Ivana Bačić
- Forensic Science Centre "Ivan Vučetić", Ministry of the Interior, Ilica 351, 10000 Zagreb, Croatia
| | - Senka Meštrović
- Department of Orthodontics, School of Dental Medicine, University of Zagreb, Gundulićeva 5, 10000 Zagreb, Croatia
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