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Zhang Y, Jin X, Savoldi F, Han J, Su RKL, Fok A, Chen J, Tsoi JKH. Validation of a double-semicircular notched configuration for mechanical testing of orthodontic thermoplastic aligner materials. J Mech Behav Biomed Mater 2024; 155:106543. [PMID: 38636445 DOI: 10.1016/j.jmbbm.2024.106543] [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: 01/19/2024] [Revised: 04/05/2024] [Accepted: 04/10/2024] [Indexed: 04/20/2024]
Abstract
The potential of using specimens with a double-semicircular-notched configuration for performing tensile tests of orthodontic thermoplastic aligner materials was explored. Unnotched and double-semicircular-notched specimens were loaded in tension using a universal testing machine to determine their tensile strength, while finite element analysis (FEA) and digital image correlation (DIC) were used to estimate stress and strain, respectively. The shape did affect the tensile strength, demonstrating the importance of unifying the form of the specimen. During the elastic phase under tension, double-semicircular-notched specimens showed similar behavior to unnotched specimens. However, great variance was observed in the strain patterns of the unnotched specimens, which exhibited greater chance of end-failure, while the strain patterns of the double-semicircular-notched specimens showed uniformity. Considerable agreement between the theoretical (FEA) and practical models (DIC) further confirmed the validity of the double-semicircular-notched models.
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Affiliation(s)
- Yuqing Zhang
- Fujian Key Laboratory of Oral Diseases, School and Hospital of Stomatology, Fujian Medical University, PR China; Dental Materials Science, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - Xiaozhuang Jin
- Dental Materials Science, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - Fabio Savoldi
- Orthodontics, Division of Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - Jianmin Han
- Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, PR China
| | - Ray Kai Leung Su
- Department of Civil Engineering, Faculty of Engineering, The University of Hong Kong, Hong Kong, China
| | - Alex Fok
- Division of Biomaterials, Department of Restorative Sciences, School of Dentistry, University of Minnesota, Minneapolis, USA
| | - Jiang Chen
- Fujian Key Laboratory of Oral Diseases, School and Hospital of Stomatology, Fujian Medical University, PR China.
| | - James Kit-Hon Tsoi
- Dental Materials Science, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
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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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Šimunović L, Blagec T, Meštrović S. Resistance of PETG Materials on Thermocycling and Brushing. Dent J (Basel) 2023; 11:dj11050135. [PMID: 37232786 DOI: 10.3390/dj11050135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/11/2023] [Accepted: 05/12/2023] [Indexed: 05/27/2023] Open
Abstract
The aim was to assess the impact of thermocycling and brushing on the surface roughness and mass of PETG material-the most commonly used for orthodontic retainers. A total of 96 specimens were exposed to thermocycling and brushing with three different kinds of toothbrushes depending on the number and thickness of the bristles. Surface roughness and mass were evaluated three times: initially, after thermocycling, and after brushing. In all four brands, both thermocycling and brushing increased surface roughness significantly (p < 0.001), with Biolon having the lowest and Track A having the highest. In terms of brushing, only Biolon samples showed statistically significant increased roughness after brushing with all three types of brushes, in comparison to Erkodur A1, where differences were not statistically significant. Thermocycling increased the mass of all samples, but a statistically significant difference was found only in Biolon (p = 0.0203), while after brushing, decreased mass was found in all specimens, statistically significant only in Essix C+ (CS 1560: p = 0.016). PETG material showed instability when exposed to external influences- thermocycling produced an increase in roughness and mass, and brushing mostly caused an increase in roughness and decrease in mass. Erkodur A1 demonstrated the greatest stability, whereas Biolon demonstrated the lowest.
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Affiliation(s)
- Luka Šimunović
- Department of Orthodontics, School of Dental Medicine Zagreb, University of Zagreb, 10000 Zagreb, Croatia
| | - Tadeja Blagec
- Department of Orthodontics, School of Dental Medicine Zagreb, University of Zagreb, 10000 Zagreb, Croatia
| | - Senka Meštrović
- Department of Orthodontics, School of Dental Medicine Zagreb, University of Zagreb, 10000 Zagreb, Croatia
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Grünheid T, Bitner TF. Wear and fatigue resistance: An in-vitro comparison of three polyethylene terephthalate glycol and thermoplastic polyurethane materials for vacuum-formed retainers. Int Orthod 2023; 21:100748. [PMID: 36934632 DOI: 10.1016/j.ortho.2023.100748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/27/2023] [Accepted: 03/04/2023] [Indexed: 03/19/2023]
Abstract
OBJECTIVE To test the wear and fatigue resistance of three materials (Essix ACE®, Taglus®, and Zendura A®) for the fabrication of vacuum-formed retainers in an artificial oral environment. MATERIAL AND METHODS Wear resistance was tested by subjecting 21 retainers of each Essix ACE®, Taglus®, and Zendura A® to 12,000 wear cycles at 75N to simulate one year of retainer wear with moderate nighttime bruxing. Post-wear retainer thickness was compared to baseline measurements to calculate wear depth. Fatigue resistance was tested by flexing 15 retainers of each material at an angle of 25 degrees for 1,825 cycles to simulate one year of removing and reinserting a retainer five times per day. Retainers were visually inspected for fractures. Pairwise t-tests with correction using Tukey's method were used to determine significant differences between materials. RESULTS The mean wear depths were 0.155±0.021mm, 0.168±0.031mm, and 0.096±0.033mm for Essix ACE®, Taglus®, and Zendura A®, respectively. The wear depth of Zendura A® was significantly lower than that of both Essix ACE® (P<0.001) and Taglus® (P<0.001). There was no significant difference in wear depth between Essix ACE® and Taglus® (P=0.312). Under the parameters set for the fatigue resistance test, fractures did not occur on any of the tested materials. CONCLUSIONS Under the assumption of moderate nighttime bruxing for one year, Zendura A® is the most wear-resistant among the materials tested. With the assumption of retainer removal and reinsertion five times per day for one year, all three materials tested have the same ability to resist fatigue.
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Affiliation(s)
- Thorsten Grünheid
- Division of Orthodontics, School of Dentistry, University of Minnesota, Minneapolis, Minnesota, USA.
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Iliadi A, Enzler V, Polychronis G, Peltomaki T, Zinelis S, Eliades T. Εffect of cleansers on the composition and mechanical properties of orthodontic aligners in vitro. Prog Orthod 2022; 23:54. [PMID: 36517652 PMCID: PMC9751251 DOI: 10.1186/s40510-022-00449-w] [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: 09/21/2022] [Accepted: 11/09/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The aim of the study was to investigate the effect of three aligner cleaners on the composition and mechanical properties of two types of orthodontic aligners. MATERIALS AND METHODS The cleaners tested were two alkaline peroxide solutions (Retainer Brite-RB; Retainer Cleaner-RC) and one peroxide-free (Steraligner-ST) and the aligners Clear Aligner (C, polyester) and Invisalign (I, polyester-urethane). The aligners were immersed in the cleaner solutions as instructed every day (15 min for RB, RC; 5 min for ST) for a two-week period. The acidity of the solutions was tested with a pH meter. The changes in the chemical composition of the aligners were studied by attenuated total-reflection Fourier transform infrared spectrometry (ATR-FTIR), while Instrumented Indentation Testing (IIT) was used for assessment of changes in Martens Hardness (HM), modulus (EIT), elastic index (nIT) and relaxation (RIT). RESULTS RB and RC were weakly acidic (pH = 6.3), whereas ST was mildly acidic (pH = 4.8). The ATR-FTIR analysis demonstrated evidence of acidic hydrolysis of C in ST and I in RB. The IIT-derived properties of I were not affected by the cleaners. However, for C a significant change was found in HM (all cleaners), nIT (all cleaners) and RIT (RB, ST). Although the chemical changes support a hydrolytic material deterioration, the results of mechanical properties may interfere with the material residual stresses during fabrication. CONCLUSIONS Caution should be exerted in the selection of aligner cleaners. The mild acidic cleanser was more aggressive to the polyester, whereas an alkaline peroxide to the polyester-urethane aligner.
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Affiliation(s)
- Anna Iliadi
- grid.5216.00000 0001 2155 0800Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece
| | - Vera Enzler
- grid.7400.30000 0004 1937 0650Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Plattenstrasse 11, 8032 Zurich, Switzerland
| | - Georgios Polychronis
- grid.5216.00000 0001 2155 0800Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece
| | - Timo Peltomaki
- grid.502801.e0000 0001 2314 6254Department of Oral and Maxillofacial Diseases, Tampere University Hospital, Tampere, Finland Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland ,grid.410705.70000 0004 0628 207XDepartment of Oral and Maxillofacial Diseases, Kuopio University Hospital, Kuopio, Finland ,grid.9668.10000 0001 0726 2490Faculty of Health Sciences, Institute of Dentistry, University of Eastern Finland, Kuopio, Finland
| | - Spiros Zinelis
- grid.5216.00000 0001 2155 0800Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece
| | - Theodore Eliades
- grid.7400.30000 0004 1937 0650Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Plattenstrasse 11, 8032 Zurich, Switzerland
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Kwok M, Porto B, Mohebi S, Zhu L, Hans M. Physical and chemical properties of five different clear thermoplastic materials. J Appl Polym Sci 2022. [DOI: 10.1002/app.51957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Man‐Hin Kwok
- Department of Macromolecular Science and Engineering Case Western Reserve University Cleveland Ohio USA
| | - Betina Porto
- Department of Orthodontics, School of Dental Medicine Case Western Reserve University Cleveland Ohio USA
| | - Shadi Mohebi
- Department of Orthodontics, School of Dental Medicine Case Western Reserve University Cleveland Ohio USA
| | - Lei Zhu
- Department of Macromolecular Science and Engineering Case Western Reserve University Cleveland Ohio USA
| | - Mark Hans
- Department of Orthodontics, School of Dental Medicine Case Western Reserve University Cleveland Ohio USA
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Alexandropoulos A, Al Jabbari YS, Zinelis S, Eliades T. Chemical and mechanical characteristics of contemporary thermoplastic orthodontic materials. AUSTRALASIAN ORTHODONTIC JOURNAL 2021. [DOI: 10.21307/aoj-2020-151] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Abstract
Aim
The aim of the present study was to characterise the chemical and mechanical properties of contemporary thermoplastic orthodontic materials.
Materials and methods
Four thermoplastic materials were tested: Clear Aligner (Scheu-Dental), ACE and A+ (Dentsply), and Invisalign (Align Technology). Eight appliances were fabricated from each material and a small portion from each was analysed by ATR-FTIR spectroscopy. The appliances were cut and, following metallographic grinding and polishing, were subjected to instrumented indentation testing (IIT) employing a Vickers indenter. Martens Hardness (HM), Indentation Modulus (EIT), Elastic to Total Work Ratio (elastic index (ηIT)) and Indentation Creep (CIT) were determined according to ISO 14577-1. The mean values of the mechanical properties were statistically analysed by one way ANOVA and Tukey Kramer multiple comparison test at a = 0.05.
Results
ATR-FTIR analysis identified that Invisalign was a polyurethane-based material, whereas the others were based on polyester, polyethylene glycol terephthalate (PETG). Invisalign showed higher hardness and modulus values, a slightly higher brittleness and lesser creep resistance compared with the PETG-based products.
Conclusions
The materials tested showed significant differences in their chemical structure and mechanical properties and therefore differences in their clinical behaviour are anticipated.
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Affiliation(s)
- Alexandras Alexandropoulos
- * Department of Biomaterials , School of Dentistry , National and Kapodistrian University of Athens , Athens , Greece
| | - Youssef S. Al Jabbari
- * Prosthetic Dental Sciences Department , College of Dentistry , King Saud University , Riyadh , Saudi Arabia
- + Dental Biomaterials Research and Development Chair , King Saud University , Riyadh , Saudi Arabia
| | - Spiros Zinelis
- * Department of Biomaterials , School of Dentistry , National and Kapodistrian University of Athens , Athens , Greece
- + Dental Biomaterials Research and Development Chair , King Saud University , Riyadh , Saudi Arabia
| | - Theodore Eliades
- ± Clinic of Orthodontics and Pediatric Dentistry , Center of Dental Medicine , University of Zurich , Zurich , Switzerland
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Influence of a bleaching agent on surface and mechanical properties of orthodontic thermoplastic retainer materials : An in vitro study. J Orofac Orthop 2021; 83:332-338. [PMID: 34170331 DOI: 10.1007/s00056-021-00312-3] [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: 09/12/2020] [Accepted: 04/24/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To investigate the effect of a tooth whitening agent on surface roughness, surface hardness, and force delivery properties of polyethylene terephthalate glycol (PETG) thermoplastic retainer materials of two different thicknesses. METHODS PETG sheets (1 mm and 1.5 mm) were thermoformed over a 30 × 60 × 10 mm3 rectangular stone model. Surface hardness, surface roughness, and results of a three-point bending test were evaluated before and after treatment (5 h daily for 14 days) with a 15% carbamide peroxide home bleaching agent. Data were analyzed using an independent sample t‑test. RESULTS Exposure of PETG specimens to the bleaching agent for 14 days significantly reduced surface hardness and increased surface roughness of samples of both thicknesses. The magnitude of force at different deflection points decreased significantly in the 1.5 mm thickness specimens treated with the bleaching agent, but no significant change was observed in the specimens with 1 mm thickness. CONCLUSION Use of a home bleaching agent could have adverse effects on surface roughness and hardness of PETG materials leading to reduced survival time of thermoplastic orthodontic retainers.
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Force Distribution of a Novel Core-Reinforced Multilayered Mandibular Advancement Device. SENSORS 2021; 21:s21103383. [PMID: 34066273 PMCID: PMC8152002 DOI: 10.3390/s21103383] [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: 04/28/2021] [Revised: 05/11/2021] [Accepted: 05/11/2021] [Indexed: 11/17/2022]
Abstract
A mandibular advancement device (MAD) is a commonly used treatment modality for patients with mild-to-moderate obstructive sleep apnea. Although MADs have excellent therapeutic efficacy, dental side effects were observed with long-term use of MADs. The aim of this study was to analyze the force distribution on the entire dentition according to the materials and design of the MADs. Three types of MADs were applied: model 1 (single layer of polyethylene terephthalate glycol (PETG)), model 2 (double layer of PETG + thermoplastic polyurethane (TPU)), and model 3 (core-reinforced multilayer). In the maxilla, regardless of the model, the incisors showed the lowest force distribution. In most tooth positions, the force distribution was lower in models 2 and 3 than in model 1. In the mandible, the mandibular second molar showed a significantly lower force in all models. The mandibular incisors, canines, and molars showed the highest force values in model 1 and the lowest values in model 3. Depending on the material and design of the device, the biomechanical effect on the dentition varies, and the core-reinforced multilayered MAD can reduce the force delivered to the dentition more effectively than the conventional single- or double-layer devices.
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Vaida LL, Bud ES, Halitchi LG, Cavalu S, Todor BI, Negrutiu BM, Moca AE, Bodog FD. The Behavior of Two Types of Upper Removable Retainers-Our Clinical Experience. CHILDREN-BASEL 2020; 7:children7120295. [PMID: 33339121 PMCID: PMC7765545 DOI: 10.3390/children7120295] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/02/2020] [Accepted: 12/14/2020] [Indexed: 12/15/2022]
Abstract
The Hawley retainer (HR) and the vacuum-formed retainer (VFR) are the most common removable retainers in orthodontic treatments. The aim of this retrospective study was to comparatively analyze the behavior of two types of removable retainers—HRs and VFRs—in terms of retainer damage, loss, and the rate of installation of mild or severe relapse that required recourse to certain therapeutic interventions. The study was performed on 618 orthodontic patients aged 11–17 years, average age 13.98 ± 1.51, out of which 57% were patients having VFRs and the remaining 43% having HRs in the upper arch. We performed an analysis of the two groups of patients—HRs group and VFRs group—at 6 months (T1) and at 12 months (T2) after the application of the retainer. The results showed that 6% of all the retainers were damaged, mostly at T2 (54.1%). Seven percent of all the retainers were lost, mostly at T1 (58.1%). Of all the patients, 9.1% presented mild relapse, mostly at T1 (58.9%), while 2.6% presented severe relapse. The VFRs were significantly more frequently associated with the occurrence of damage than the HRs (p < 0.001). Severe relapse was more frequently associated with the HRs rather than with VFRs (p < 0.05).
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Affiliation(s)
- Luminita Ligia Vaida
- Department of Dentistry, Faculty of Medicine and Pharmacy, University of Oradea, 1 Universitatii Str., 410087 Oradea, Romania; (L.L.V.); (B.I.T.); (B.M.N.); (A.E.M.)
| | - Eugen Silviu Bud
- Department of Orthodontics, University of Medicine and Pharmacy Science and Technology G.E Palade, 38 Gh. Marinescu Str., 540139 Targu Mures, Romania
- Correspondence: (E.S.B.); (L.G.H.)
| | - Liliana Gabriela Halitchi
- Department of Clinical Disciplines, Faculty of Dentistry, Apollonia University of Iasi, 2 Muzicii Str., 700399 Iasi, Romania
- Correspondence: (E.S.B.); (L.G.H.)
| | - Simona Cavalu
- Department of Preclinical Sciences, Faculty of Medicine and Pharmacy, University of Oradea, 1 Universitatii Str., 410087 Oradea, Romania;
| | - Bianca Ioana Todor
- Department of Dentistry, Faculty of Medicine and Pharmacy, University of Oradea, 1 Universitatii Str., 410087 Oradea, Romania; (L.L.V.); (B.I.T.); (B.M.N.); (A.E.M.)
| | - Bianca Maria Negrutiu
- Department of Dentistry, Faculty of Medicine and Pharmacy, University of Oradea, 1 Universitatii Str., 410087 Oradea, Romania; (L.L.V.); (B.I.T.); (B.M.N.); (A.E.M.)
| | - Abel Emanuel Moca
- Department of Dentistry, Faculty of Medicine and Pharmacy, University of Oradea, 1 Universitatii Str., 410087 Oradea, Romania; (L.L.V.); (B.I.T.); (B.M.N.); (A.E.M.)
| | - Florian Dorel Bodog
- Department of Surgery, Faculty of Medicine and Pharmacy, University of Oradea, 1 Universitatii Str., 410087 Oradea, Romania;
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Porojan L, Vasiliu RD, Porojan SD, Bîrdeanu MI. Surface Quality Evaluation of Removable Thermoplastic Dental Appliances Related to Staining Beverages and Cleaning Agents. Polymers (Basel) 2020; 12:polym12081736. [PMID: 32756439 PMCID: PMC7464035 DOI: 10.3390/polym12081736] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 07/30/2020] [Accepted: 08/01/2020] [Indexed: 01/04/2023] Open
Abstract
(1) Background: Thermoplastic materials are not inert and subject to changes in the oral environment, which affect their surface quality. Color stability and topographic characteristics of clear thermoplastic appliances are critical considerations. The study aimed to evaluate the optical changes and surface topography of different thermoplastic materials related to staining beverages and cleaning agents. (2) Methods: Thermoplastic polyethylene terephthalate glycol (PET-G) material specimens were selected for the study: S (Duran, Scheu-Dental GmbH, Iserlohn, Germany), D (Biolon, Dreve Dentamid GmbH, Unna, Germany), and B (Crystal, Bio Art Dental Equipment, Sao Carlos, Brazil). Four different media were involved for immersion: coffee (C) and black tea (T) at 55 °C, Coca-Cola (K) at 5 °C, and distilled water (W) at 22 °C. As for cleaning, chemical options and mechanical brushing were selected (P-powder, T-tablets, and X-brushing). Color changes, and mean surface roughness were measured at 24 h, 48 h, and after 7 days. Statistical analysis was performed. After the testing period, atomic force microscopy (AFM) analyses and SEM images were registered in order to characterize the surface topography. (3) Results: Quantitative color change evaluations revealed a slight change in color after 24 h and an extremely marked change after 48 h, respective 7 days. Mean roughness values are kept below the clinically acceptable limit of 0.20 µm for all samples. Related to mean nanoroughness values Sa, and 3D evaluations of the surface quality, Biolon samples have demonstrated the most constant behavior, while Crystal samples are visibly influenced by water immersion. Related to the cleaning method, the topography of Duran samples was influenced by mechanical brushing. (4) Conclusions: Nanoscale investigations provided high accuracy and more realistic surface quality examinations of the examined samples compared to profilometry. Both SEM and AFM should be used for a more detailed description of the surface topography.
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Affiliation(s)
- Liliana Porojan
- Department of Dental Prostheses Technology (Dental Technology), “Victor Babeș” University of Medicine and Pharmacy Timișoara, Romania, Eftimie Murgu Sq. no. 2, 300041 Timișoara, Romania;
| | - Roxana-Diana Vasiliu
- Department of Dental Prostheses Technology (Dental Technology), “Victor Babeș” University of Medicine and Pharmacy Timișoara, Romania, Eftimie Murgu Sq. no. 2, 300041 Timișoara, Romania;
- Correspondence: ; Tel.: +40-745225523
| | - Sorin-Daniel Porojan
- Department of Oral Rehabilitation (Dental Technology), “Victor Babeș” University of Medicine and Pharmacy Timișoara, Romania, Eftimie Murgu Sq. no. 2, 300041 Timișoara, Romania;
| | - Mihaela-Ionela Bîrdeanu
- National Institute for Research and Development in Electrochemistry and Condensed Matter, 300569 Timisoara, Romania;
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12
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Suter F, Zinelis S, Patcas R, Schätzle M, Eliades G, Eliades T. Roughness and wettability of aligner materials. J Orthod 2020; 47:223-231. [PMID: 32615846 DOI: 10.1177/1465312520936702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE The characterisation of surface roughness and energy of contemporary thermoplastic materials used in manufacturing of orthodontic aligners. DESIGN In vitro, laboratory study. MATERIALS AND METHODS Four commercially available thermoplastic materials were selected (CA-medium/CAM, Essix-copopyester/COP, Duran/DUR and Erkodur/ERK). Five disks from each, as received, material were tested and subjected to: (1) reflected light microscopy; (2) optical profilometry for the estimation of Sa, Sz, Sq, Sdr, Sc, Sv surface roughness parameters (n = 5); and (3) contact angle measurements with a Zisman series of liquids for the estimation of critical surface tension (γC), total work of adhesion (WA), as well as the work of adhesion due to polar (WP) and dispersion (WD) components employing the Zisman method (n = 5/liquid). Thermoformed disks were prepared against a dental stone model and the roughness parameters were calculated again Statistical analysis was performed by one-way ANOVA/ Tukey multiple comparison test and t-test (a = 0.05). RESULTS Microscopic and profilometric analyses revealed a smooth surface texture in the as-received materials, but a very rough texture after thermoforming, with insignificant differences within each state. Significant differences in the as-received state were found in the surface energy parameters; CAM showed the lowest γC and the highest WA, WP, WD, whereas ERK with the highest γC demonstrated lower WA. COP and DUR were ranked in an intermediate group regarding γC, with a statistically significant difference in WA between them, mainly attributed to the lower WP of the former. CONCLUSION Given the differences in surface energy parameters and the lack of roughness differences within the as received or thermoformed groups, it may be concluded that variations in the plaque retaining capacity are anticipated, determined by γC, WA and the WP, WD components.
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Affiliation(s)
- Fabienne Suter
- Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, ZH, Switzerland
| | - Spiros Zinelis
- Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, ZH, Switzerland.,Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Athens, Attica, Greece
| | - Raphael Patcas
- Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, ZH, Switzerland
| | - Marc Schätzle
- Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, ZH, Switzerland
| | - George Eliades
- Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Athens, Attica, Greece
| | - Theodore Eliades
- Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, ZH, Switzerland
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ATR-FTIR Analysis and One-Week Stress Relaxation of Four Orthodontic Aligner Materials. MATERIALS 2020; 13:ma13081868. [PMID: 32316154 PMCID: PMC7215293 DOI: 10.3390/ma13081868] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 02/06/2023]
Abstract
The aim of this study was to estimate possible differences in the chemical composition and relaxation of orthodontic aligner materials. Four commercially available thermoplastic materials CAM (Scheu-Dental, Iserlohn, Germany), COP (Essix, Dentsply Raintree Essix Sarasota,FL, USA), DUR (Great Lakes Dental Technologies, Tonawanda, NY) and ERK (Erkodent Erich Kopp, Pfalzgrafenweiler Germany) were included in this study. Rectangular strips from each material were prepared according to the manufacturer's instructions and subjected to attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and stress relaxation characterization. The reduction in applied stress (RAS) after one week was estimated and statistically analyzed by one-way ANOVA at the 0.05 level of significance. All specimens were subjected to optical microscopy before and after stress relaxation testing under transmittance polarized illumination. ATR-FTIR microscopy revealed that all materials are made of polyethylene terephthalate glycol (PETG) while no significant differences were identified in RAS values among materials tested, which ranged from 6%-10% (p ≥ 0.05). All samples illustrated the developments of shear bands during relaxation testing according to optical microscopy findings. The tested materials illustrated similar chemical composition and relaxation behavior and thus no differences in their clinical efficacy are anticipated.
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Mechanical Characterization of Thermoplastic Aligner Materials: Recommendations for Test Parameter Standardization. JOURNAL OF HEALTHCARE ENGINEERING 2019; 2019:8074827. [PMID: 31275537 PMCID: PMC6560334 DOI: 10.1155/2019/8074827] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 04/16/2019] [Accepted: 05/13/2019] [Indexed: 01/06/2023]
Abstract
Background Understanding of the different mechanical properties of thermoplastic materials is essential for a successful aligner treatment and further developments. However, data of previous material testing studies are scarcely comparable. Aim of the current study was to evaluate the different test parameters to lay the foundations for guidelines for future, more standardized three-point-bending aligner material tests. Materials and Methods Several parameters concerning the specimen preparation and experimental three-point-bending setup were varied. The specimens were collected from polyethylene terephthalate glycol (PET-G) Duran® foils with different thicknesses. Both raw foils and foils thermoformed using different geometrical forms were investigated. The three-point-bending tests were performed using span lengths of 8 and 16 mm and variable deflection ranges between 0.1 and 0.2 mm. The influence of water storage on the bending forces was studied using unloaded and loaded specimens. Experimental results were validated using a beam cantilever mathematical model. Results Local macroscopic cracks after long-term loading could be avoided by keeping the deflections within a thickness-dependent individual range. The mathematical calculations confirmed that these individual deflection ranges lead to local stresses between 14 and 18 MPa. Constantly loaded specimens immersed for 24 hours in water showed a decrease of the bending force by 50%. This reduction was much smaller for the unloaded specimens (14%). Conclusion During clinical aligner therapy, very small bending deflections are combined with small distances between the tooth surface regions supporting the aligner. In vitro aligner material testing by three-point bending should consider these geometrical aspects, while keeping the material stresses in a range between 14 and 18 MPa to avoid local microcracks. Considering these aspects, thickness-dependent deflections were established for three-point bending of the PET-G specimen for a span length of 8 mm. We recommend the application of these test parameters in future aligner material studies to achieve valid and comparable test results.
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Wible E, Agarwal M, Altun S, Ramir T, Viana G, Evans C, Lukic H, Megremis S, Atsawasuwan P. Long-term effects of various cleaning methods on polypropylene/ethylene copolymer retainer material. Angle Orthod 2019; 89:432-437. [PMID: 30605015 DOI: 10.2319/060818-429.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES To evaluate long-term light transmittance, surface roughness, and flexural modulus of polypropylene/ethylene copolymer retainer material after exposure to different cleaning methods. MATERIALS AND METHODS Standardized polypropylene/ethylene copolymer retainer specimens (n = 70, 50.8 mm × 12.7 mm × 1.0 mm) were subjected to seven chemical cleaning solutions: Invisalign cleaning crystals, Retainer Brite, Polident, Listerine mouthwash, 2.5% acetic acid, 0.6% NaClO, and 3% H2O2 for 6 months. The specimens were exposed to the different solutions twice a week for 15 minutes or according to manufacturer's instructions, then stored in artificial saliva at 37°C. Another group of specimens (n = 10) were brushed with a standardized toothbrushing machine for 2 minutes twice a week. At baseline and 6 months, light transmittance, surface roughness, and flexural modulus of the specimens were quantified using spectrophotometry, profilometry and three-point bend testing, respectively. Qualitative analysis was performed using a scanning electron microscope (SEM). Statistical analyses were performed at a significance level of .05. RESULTS The results showed that light transmittance decreased significantly from baseline for all cleaning methods at 6 months. For an individual method, no significant differences were observed between specimens at baseline and 6 months in surface roughness and flexural modulus. No discernible differences in surface features were observed on SEM images. CONCLUSIONS The results indicate that different cleaning methods affect the long-term light transmittance of the studied polypropylene/ethylene copolymer retainer material. However, for an individual cleaning method, no significant differences were shown for surface roughness or flexural modulus values at 6-months compared to baseline.
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Doğramacı EJ, Chubb D, Rossi-Fedele G. Orthodontic thermoformed retainers: a two-arm laboratory study into post-fabrication outcomes. Aust Dent J 2018; 63:347-355. [PMID: 29660138 DOI: 10.1111/adj.12610] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2018] [Indexed: 02/28/2024]
Abstract
BACKGROUND Retainers are commonly used to maintain post-orthodontic occlusion stability. We aimed to determine post-fabrication thickness and thinning rate of thermoformed retainers. METHODS Forty-eight retainers were fabricated from polyethylenterepthalat-glycol copolyester or polypropylene blanks, using vacuum- or pressure-thermoforming. Retainer thickness was measured at multiple locations. RESULTS Thinning rate had a broad range: the mid-labial incisor region of 1 mm polyethylenterepthalat-glycol copolyester pressure-thermoformed mandibular retainers had the greatest thinning rate (68.25 ± 8.26%) and smallest mean post-fabrication thickness (0.32 ± 0.08 mm). Polyethylenterepthalat-glycol copolyester retainers were 0.11 mm thinner than polypropylene (P=0.0222), and polypropylene retainers were 0.21 mm thicker, when pressure-thermoformed (P<0.0001). The interaction of manufacturing method and material used, and tooth type, explained over a third of the variability in the post-fabrication thickness of these retainers. Maxillary retainers made from 1 mm blanks were 0.04 mm thicker in the incisor region compared with the molar region (P=0.0492). CONCLUSIONS Thermoformed retainers do no thin uniformly against individual teeth and have variable intra- and inter-arch post-fabrication thicknesses. There is no clear benefit in using a specific type of thermoforming machine or material for increasing post-fabrication thickness or reducing thinning rate. Blank thickness and tooth morphology influence these outcomes.
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Affiliation(s)
- E J Doğramacı
- Adelaide Dental School, The University of Adelaide, Adelaide, South Australia, Australia
| | - Dwr Chubb
- Adelaide Dental School, The University of Adelaide, Adelaide, South Australia, Australia
| | - G Rossi-Fedele
- Adelaide Dental School, The University of Adelaide, Adelaide, South Australia, Australia
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Ruyi W, Zhihe Z, Yu L. [Current situation and prospect for orthodontic thermoplastic materials]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2018; 36:87-91. [PMID: 29595003 DOI: 10.7518/hxkq.2018.01.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Aesthetic and comfortable transparent retainers and clear plastic appliances are becoming increasingly popular, and their components, especially thermoplastic materials, are gradually attracting widespread interest. Orthodontic thermoplastic materials are versatile polymers, and thus their properties, such as force delivery, force relaxation, and aging properties have been comprehensively studied. Meanwhile, blending modification technology has been applied for the acquisition of novel materials with enhanced characteristics. In this paper, we review the types and properties of thermoplastic materials, the development process they undergo, factors that influence their properties, and some development prospects.
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Affiliation(s)
- Wang Ruyi
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Zhao Zhihe
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Li Yu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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Zafeiriadis AA, Karamouzos A, Athanasiou AE, Eliades T, Palaghias G. An in vivo spectrophotometric evaluation of Vivera® and Essix® clear thermoplastic retainer discolouration. AUSTRALASIAN ORTHODONTIC JOURNAL 2018. [DOI: 10.21307/aoj-2020-053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Abstract
Aim
To assess the in vivo colour alterations of two different clear thermoplastic retainers.
Methods
Thirty patients were randomly allocated into two Groups (N = 15) following the completion of active orthodontic treatment. Group 1 received Vivera® and Group 2 Essix® C+ thermoplastic retainers. Each patient was provided with two fabricated retainers (one for use and the other to serve as a control). The CIELAB parameters of the patients’ upper central incisors were measured with a SpectroShade™ spectrophotometer immediately after retainer placement (T0) and again after 15 days (T1), one month (T2) and three months (T3). The measurements were also performed on teeth without the retainer in place. ΔE differences were calculated.
Methods
ΔE changes from T0 to Tp T2 or T3 showed no statistically significant differences between Groups 1 and 2 within any combination of measurements or teeth. ΔEļŢ3-Ţ0ļ changes for used retainers were 1.55 times higher than control appliances (p = 0.002) and 1.44 times higher than for teeth-only (p = 0.004). For used retainers, changes between T3 and T0 were 1.56 times higher than between T and T0 and 1.47 higher than between T2 and T0 (p < 0.001). There were no statistically significant differences in ΔE between teeth 11 and 21.
Results
Used retainers exhibited greater colour change than control appliances or teeth-only readings, and increased commensurate with the duration of use. Vivera® and Essix® retainers exhibited similar colour stability. All differences observed were considered clinically acceptable (ΔE < 3.7), although prolonged use could cause clinically significant colour changes.
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Affiliation(s)
- Anastasios A Zafeiriadis
- Department of Orthodontics , Faculty of Dentistry, School of Health Sciences, Aristotle University of Thessaloniki , Thessaloniki , Greece
| | - Andreas Karamouzos
- Department of Orthodontics , Faculty of Dentistry, School of Health Sciences, Aristotle University of Thessaloniki , Thessaloniki , Greece
| | - Athanasios E Athanasiou
- Hamdan Bin Mohammed College of Dental Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences , Dubai , United Arab Emirates
| | - Theodore Eliades
- Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich , Zurich , Switzerland
| | - George Palaghias
- Departments of Basic Dental Sciences and Operative Dentistry, Faculty of Dentistry, School of Health Sciences, Aristotle University of Thessaloniki , Thessaloniki , Greece
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Ahn HW, Ha HR, Lim HN, Choi S. Effects of aging procedures on the molecular, biochemical, morphological, and mechanical properties of vacuum-formed retainers. J Mech Behav Biomed Mater 2015; 51:356-66. [PMID: 26282078 DOI: 10.1016/j.jmbbm.2015.07.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 07/25/2015] [Accepted: 07/27/2015] [Indexed: 10/23/2022]
Abstract
The influence of intraoral exposure procedures on the physical characteristics of thermoplastic vacuum-formed retainers (VFRs) is still unclear. The effects of thermoforming and intraoral use on the molecular, chemical, morphological, and mechanical properties of thermoplastic VFRs were investigated. VFRs with a 0.8-mm-thick thermoplastic PETG sheet acquired from 48 patients were investigated with two aging procedures, including vacuum forming and intraoral exposure, for 2-week and 6-month. Eight evaluating sites for thermoplastic VFRs were assessed with seven analytical techniques. LM, SEM, and AFM microscopic findings showed that the surface characteristics increased with increasing in vivo exposure time (a four-fold increase) and varied depending on the sites evaluated (an occlusal surface). Raman and EDX spectroscopic findings showed that aging procedures led to a significant change in the molecular composition of VFRs, leading to a decrease in the composition rate of carbon (C) and the presence of silicon (Si), phosphorus (P), and calcium (Ca). Compressive strength and tensile tests showed that aging procedures led to a significant increase (P<0.01) in ultimate tensile strength, elastic modulus, the stored energy at a 6-mm deflection (u6 mm), and the compressed load at a 3-mm deflection (σ3 mm). Thermoforming led to a smoother surface and no crystallization of PETG sheets. Intraoral exposure accelerated changes in surface morphology, tensile strength, and elastic modulus of VFRs. This change was site-specific and enhanced with an increase in intraoral exposure time. Therefore, thermoforming and in vivo oral exposure procedures led to the molecular, morphological, and mechanical properties of thermoplastic VFRs.
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Affiliation(s)
- Hyo-Won Ahn
- Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul 130-702, Republic of Korea
| | - Hye-Ryun Ha
- Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul 130-702, Republic of Korea
| | - Ho-Nam Lim
- Center for Dental Materials, Kyung Hee University, Seoul 130-701, Republic of Korea; Department of Dental Materials, School of Dentistry, Kyung Hee University, Seoul 130-702, Republic of Korea
| | - Samjin Choi
- Department of Biomedical Engineering, College of Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea; Department of Medical Engineering, Kyung Hee University, Seoul 130-701, Republic of Korea.
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Mai W, He J, Meng H, Jiang Y, Huang C, Li M, Yuan K, Kang N. Comparison of vacuum-formed and Hawley retainers: a systematic review. Am J Orthod Dentofacial Orthop 2014; 145:720-7. [PMID: 24880842 DOI: 10.1016/j.ajodo.2014.01.019] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 01/01/2014] [Accepted: 01/01/2014] [Indexed: 10/25/2022]
Abstract
INTRODUCTION Hawley retainers (HRs) and vacuum-formed retainers (VFRs) are the 2 most commonly used retainers in orthodontics. However, the basis for selection of an appropriate retainer is still a matter of debate among orthodontists. In this systematic review, we evaluated the differences between VFRs and HRs. METHODS Electronic databases (PubMed, EMBASE, Cochrane Library, ISI Web of Science, LILACS, and Pro-Quest) were searched with no language restriction. The relevant orthodontic journals and reference lists were checked for all eligible studies. Two article reviewers independently screened the retrieved studies, extracted the data, and evaluated the quality of the primary studies. RESULTS A total of 89 articles were retrieved in the initial search. However, only 7 articles met the inclusion criteria. Some evidence suggested that no difference exists to distinguish between the HRs and VFRs with respect to changes in intercanine and intermolar widths after orthodontic retention. In terms of occlusal contacts, cost effectiveness, patient satisfaction, and survival time, there was insufficient evidence to support the use of VFRs over HRs. CONCLUSIONS Additional high-quality, randomized, controlled trials concerning these retainers are necessary to determine which retainer is better for orthodontic procedures.
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Affiliation(s)
- Wenjia Mai
- Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China
| | - Jin'an He
- Senior instructor, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China
| | - Hongying Meng
- Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China
| | - Yanping Jiang
- Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China
| | - Chaoxiao Huang
- Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China
| | - Min Li
- Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China
| | - Kan Yuan
- Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China
| | - Na Kang
- Associate professor and director, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China.
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Pithon MM, Sousa ÉLSM, Fogaça DNL, Silva WSD, Rodrigues LB, Coqueiro RS. The acrylic's design or the addition of internal orthodontic wire changes the resistance of orthodontic plates? REVISTA DE ODONTOLOGIA DA UNESP 2013. [DOI: 10.1590/s1807-25772013000600010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE: Evaluate resistance of Hawley retainers in three different acrylic configurations in order to evaluate if its format or the addition of internal wire interferes in its resistance. MATERIAL AND METHOD: 45 Hawley retainers were fabricated, divided into three groups (n = 15): Group 1 - acrylic covering the entire hard palate, Group 2 - plate with relief at the deepest region of the palate, leaving it with a "U" conformation and Group 3 - similar to Group 2, with the addition of 0.7mm wire 2cm internally of the acrylic at the region of the palatine ridges. The compressive strength was tested in a universal mechanical testing machine (Stable Microsystems, London, United Kingdom), measuring the applied force until plate rupture occurred. The differences between the formats being compared by the Kruskal-Wallis test. The significance level was set at 5% (α = 0.05). RESULT: Group 1 showed the highest resistance, with a mean of about five times higher than Group 2 and three times higher than Group 3. CONCLUSION: acrylic reduction in dental retainer plates is directly related to the reduction of its compressive strength, the inclusion of orthodontic wire inside the acrylic increases the resistance of the plate, being a good alternative when more comfort is wanted for the patient without loss of the mechanical characteristics of the dental retainers.
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Sun J, Yu YC, Liu MY, Chen L, Li HW, Zhang L, Zhou Y, Ao D, Tao R, Lai WL. Survival time comparison between Hawley and clear overlay retainers: a randomized trial. J Dent Res 2011; 90:1197-201. [PMID: 21771797 DOI: 10.1177/0022034511415274] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The objectives of this study were to compare the survival time of the Hawley retainer (HR) and the clear overlay retainer (COR) over one-year follow-up and to analyze risk factors contributing to their breakage. In this randomized, controlled clinical trial, we assigned 120 adolescent patients to receive either the HR or the COR. All specific data on breakage dates, the reasons for breakage, and the broken parts of the retainers were recorded. A survival analysis was used to describe retainer survival over time. No significant differences were observed in survival times between the 2 groups for either the maxillary retainer (p = 0.254) or the mandibular retainer (p = 0.188). Both retainers tended to fracture, but the fracture locations were different. The findings indicate that clinicians should avoid increasing buccal root torque and reinforce the retainer base plates. Breakage rates may not influence the choice of retainer (Trial Registration number is ChiCTR-TRC-00000055).
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Affiliation(s)
- J Sun
- Department of Orthodontics, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, People's Republic of China
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Bárány T, Czigány T, Karger-Kocsis J. Application of the essential work of fracture (EWF) concept for polymers, related blends and composites: A review. Prog Polym Sci 2010. [DOI: 10.1016/j.progpolymsci.2010.07.001] [Citation(s) in RCA: 194] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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