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Wu J, Wang X, Jiang J, Bai Y. Fabrication of a novel aesthetic orthodontic bracket and evaluation of friction properties between PEEK and stainless steel wires. Technol Health Care 2024; 32:269-278. [PMID: 37393452 DOI: 10.3233/thc-230001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/03/2023]
Abstract
BACKGROUND Polyetheretherketone (PEEK) is a polyaromatic semi-crystalline thermoplastic polymer with mechanical and lubrication properties favorable for biomedical applications. Despite of its aesthetic appearance, ceramic brackets are unsatisfactory in brittleness and thickness, while PEEK is a potential material for aesthetic orthodontic brackets. OBJECTIVE To fabricate a novel aesthetic orthodontic bracket and evaluate friction properties of PEEK and stainless steel wires. METHODS All polyether ether ketone (PEEK) and ceramic samples disks were made into disks (diameter, 5 mm; thickness, 2 mm). The tested surfaces of PEEK were ground with #600, #800 and #1200 SiC papers, followed by polishing with Sof-Lex kit (3M ESPE, USA). The surface roughness was tested using a laser profilometer device (VK-X200, Keyence, Japan). The COFs of the specimens and stainless steel (SS) archwires were tested using a Universal Micro-Tribotester (UMT-3, Bruker, USA). The wear scratches on the materials' surfaces were examined by using a scanning electron microscope (SEM) (Hitachi SU8010). The elastic modulus and hardness of samples were examined with a nano-indenter (XP, Keysight Technologies, USA). RESULTS The mean surface roughness of PEEK and Ceramic are 0.320 ± 0.028 μm and 0.343 ± 0.044 μm, respectively. PEEK has a lower Friction coefficient than Ceramic and the difference between the two groups was statistically significant (P< 0.05). The abrasive wear of Ceramic was the main wear style and was characterized by the observation of chipping fractures, while PEEK surface looked smooth without obvious scale-like desquamations and granular debris, indicating adhesive wear. CONCLUSION Within the limitations of the present study, PEEK shows lower coefficient of friction than ceramic. PEEK has excellent properties such as low friction coefficient, smooth surface and good mechanical properties, and thus meets the requirements for orthodontic brackets. It is considered as a potential bracket material with both low friction and aesthetic performance.
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Affiliation(s)
- Jiaqi Wu
- First Clinical Division, Peking University Hospital of Stomatology, Beijing, China
- First Clinical Division, Peking University Hospital of Stomatology, Beijing, China
| | - Xiujing Wang
- First Clinical Division, Peking University Hospital of Stomatology, Beijing, China
- First Clinical Division, Peking University Hospital of Stomatology, Beijing, China
| | - Jiuhui Jiang
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Yunyang Bai
- Department of Geriatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, China
- National Center for Stomatology, Peking University School and Hospital of Stomatology, Beijing, China
- National Clinical Research Center for Oral Diseases, Peking University School and Hospital of Stomatology, Beijing, China
- National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Peking University School and Hospital of Stomatology, Beijing, China
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Juerchott A, Roser CJ, Saleem MA, Nittka M, Lux CJ, Heiland S, Bendszus M, Hilgenfeld T. Diagnostic compatibility of various fixed orthodontic retainers for head/neck MRI and dental MRI. Clin Oral Investig 2023; 27:2375-2384. [PMID: 36640179 PMCID: PMC10160193 DOI: 10.1007/s00784-023-04861-2] [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: 05/24/2022] [Accepted: 01/03/2023] [Indexed: 01/15/2023]
Abstract
OBJECTIVES To evaluate the diagnostic MRI compatibility of different fixed orthodontic retainers using a high-resolution 3D-sequence optimized for artifact reduction. MATERIALS AND METHODS Maxillary and mandibular retainers made of five different materials were scanned in vitro and in vivo at 3 T MRI using an MSVAT-SPACE sequence. In vitro, artifact volumes were determined for all maxillary and mandibular retainers (AVmax; AVmand). In vivo, two independent observers quantified the extent of artifacts based on the visibility of 124 dental and non-dental landmarks using a five-point rating scale (1 = excellent, 2 = good, 3 = acceptable, 4 = poor, 5 = not visible). RESULTS Rectangular-steel retainers caused the largest artifacts (AVmax/AVmand: 18,060/15,879 mm3) and considerable diagnostic impairment in vivo (mean landmark visibility score ± SD inside/outside the retainer areas: 4.8 ± 0.8/2.9 ± 1.6). Smaller, but diagnostically relevant artifacts were observed for twistflex steel retainers (437/6317 mm3, 3.1 ± 1.7/1.3 ± 0.7). All retainers made of precious-alloy materials produced only very small artifact volumes (titanium grade 1: 70/46 mm3, titanium grade 5: 47/35 mm3, gold: 23/21 mm3) without any impact on image quality in vivo (each retainer: visibility scores of 1.0 ± 0.0 for all landmarks inside and outside the retainer areas). CONCLUSIONS In contrast to steel retainers, titanium and gold retainers are fully compatible for both head/neck and dental MRI when using MSVAT-SPACE. CLINICAL RELEVANCE This study demonstrates that titanium and gold retainers do not impair the diagnostic quality of head/neck and dental MRI when applying an appropriate artifact-reduction technique. Steel retainers, however, are not suitable for dental MRI and can severely impair image quality in head/neck MRI of the oral cavity.
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Affiliation(s)
- Alexander Juerchott
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany.
| | - Christoph J Roser
- Department of Orthodontics and Dentofacial Orthopedics, Heidelberg University Hospital, Heidelberg, Germany
| | - Muhammad Abdullah Saleem
- Division of Experimental Radiology, Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | | | - Christopher J Lux
- Department of Orthodontics and Dentofacial Orthopedics, Heidelberg University Hospital, Heidelberg, Germany
| | - Sabine Heiland
- Division of Experimental Radiology, Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Martin Bendszus
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Tim Hilgenfeld
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
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Johannsen KM, de Carvalho E Silva Fuglsig JM, Hansen B, Wenzel A, Spin-Neto R. Magnetic resonance imaging artefacts caused by orthodontic appliances and/or implant-supported prosthesis: a systematic review. Oral Radiol 2023; 39:394-407. [PMID: 36178613 DOI: 10.1007/s11282-022-00652-9] [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: 06/23/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022]
Abstract
OBJECTIVES Dental materials, including orthodontic appliances and implants, are commonly mentioned as a possible source of artefacts in magnetic resonance imaging (MRI). The aim of the present study was to undertake a systematic review of the relevant literature on MR image artefacts due to dental materials, limited to orthodontic appliances and implant-supported dental prosthesis, on both technical and diagnostic levels. METHODS The MEDLINE (PubMed) bibliographic database was searched up to September 2020. The search was limited to studies published in English, using the search string: (MRI or magnetic resonance) and (artefact or artifact) and (dental or ortho or implant or restoration or restorative). The studies were assessed independently by three reviewers, focusing on the following parameters: MRI sequences, tested materials, assessed parameters, efficacy level and outcome. RESULTS The search strategy yielded 31 studies, which were included in this systematic review. These studies showed that metallic dental materials, commonly present in orthodontic appliances and implant-supported dental prosthesis led to diverse types/severities of artefacts in MR images. Fifteen studies were in vivo, based on human subjects. The studies differed substantially in terms of tested materials, assessed parameters, and outcome measurements. CONCLUSIONS Metallic dental materials cause artefacts of diverse types and severities in MR images of the head and neck region. However, the diagnostic relevance of the investigated artefacts for the diverse MRI applications is yet to be studied.
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Affiliation(s)
- Katrine Mølgaard Johannsen
- Department of Dentistry and Oral Health, Oral Radiology, Aarhus University, Vennelyst Boulevard 9, 8000, Aarhus, Denmark.
| | | | - Brian Hansen
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Ann Wenzel
- Department of Dentistry and Oral Health, Oral Radiology, Aarhus University, Vennelyst Boulevard 9, 8000, Aarhus, Denmark
| | - Rubens Spin-Neto
- Department of Dentistry and Oral Health, Oral Radiology, Aarhus University, Vennelyst Boulevard 9, 8000, Aarhus, Denmark
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Lyros I, Tsolakis IA, Maroulakos MP, Fora E, Lykogeorgos T, Dalampira M, Tsolakis AI. Orthodontic Retainers-A Critical Review. CHILDREN (BASEL, SWITZERLAND) 2023; 10:children10020230. [PMID: 36832359 DOI: 10.3390/children10020230.pmid:36832359;pmcid:pmc9954726] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 01/23/2023] [Accepted: 01/26/2023] [Indexed: 05/25/2023]
Abstract
The achievement of aesthetic, functional occlusion should not mark the end of the orthodontic intervention. To prevent relapse, retention needs advance planning, and may vary in duration. This review aims to present and comment on the available means of retention. The ever-popular, passive Hawley-like removable appliances are credible in maintaining the desired occlusion. Modifications are the removable appliance Wrap Around, having the labial archwire extending to the premolars; the translucent retainer, Astics, a unique aesthetic Hawley-type device; and the reinforced removable retainer, which features a metallic grid reinforcing the acrylic base. Vacuum-formed retainers are easy to fabricate and are readily prescribed. By contrast, fixed retainers are made of orthodontic wire and composite resin bonded on the lingual or palatal surfaces of the anterior teeth. Patient-related variables need evaluation to select the appropriate retainer, while patients ought to realize the importance of retention and comply with offered guidance. Overall, the orthodontist is responsible for keeping the patient informed on the properties and the duration of retention, even before starting active orthodontic treatment.
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Affiliation(s)
- Ioannis Lyros
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Ioannis A Tsolakis
- Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, 54623 Thessaloniki, Greece
| | - Michael P Maroulakos
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Eleni Fora
- Department of Oral Medicine & Pathology and Hospital Dentistry, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | | | | | - Apostolos I Tsolakis
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
- Department of Orthodontics, Case Western Reserve University, Cleveland, OH 44106, USA
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5
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Lyros I, Tsolakis IA, Maroulakos MP, Fora E, Lykogeorgos T, Dalampira M, Tsolakis AI. Orthodontic Retainers-A Critical Review. CHILDREN (BASEL, SWITZERLAND) 2023; 10:children10020230. [PMID: 36832359 PMCID: PMC9954726 DOI: 10.3390/children10020230] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 01/23/2023] [Accepted: 01/26/2023] [Indexed: 01/31/2023]
Abstract
The achievement of aesthetic, functional occlusion should not mark the end of the orthodontic intervention. To prevent relapse, retention needs advance planning, and may vary in duration. This review aims to present and comment on the available means of retention. The ever-popular, passive Hawley-like removable appliances are credible in maintaining the desired occlusion. Modifications are the removable appliance Wrap Around, having the labial archwire extending to the premolars; the translucent retainer, Astics, a unique aesthetic Hawley-type device; and the reinforced removable retainer, which features a metallic grid reinforcing the acrylic base. Vacuum-formed retainers are easy to fabricate and are readily prescribed. By contrast, fixed retainers are made of orthodontic wire and composite resin bonded on the lingual or palatal surfaces of the anterior teeth. Patient-related variables need evaluation to select the appropriate retainer, while patients ought to realize the importance of retention and comply with offered guidance. Overall, the orthodontist is responsible for keeping the patient informed on the properties and the duration of retention, even before starting active orthodontic treatment.
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Affiliation(s)
- Ioannis Lyros
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
- Correspondence:
| | - Ioannis A. Tsolakis
- Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, 54623 Thessaloniki, Greece
| | - Michael P. Maroulakos
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Eleni Fora
- Department of Oral Medicine & Pathology and Hospital Dentistry, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | | | | | - Apostolos I. Tsolakis
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
- Department of Orthodontics, Case Western Reserve University, Cleveland, OH 44106, USA
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6
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Roser CJ, Hilgenfeld T, Saleem MA, Rückschloß T, Heiland S, Bendszus M, Lux CJ, Juerchott A. In vivo assessment of artefacts in MRI images caused by conventional twistflex and various fixed orthodontic CAD/CAM retainers. J Orofac Orthop 2023:10.1007/s00056-022-00445-z. [PMID: 36700953 DOI: 10.1007/s00056-022-00445-z] [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: 05/25/2022] [Accepted: 12/12/2022] [Indexed: 01/27/2023]
Abstract
PURPOSE To assess magnetic resonance imaging (MRI) artefacts caused by different computer-aided design/computer-aided manufacturing (CAD/CAM) retainers in comparison with conventional hand bent stainless steel twistflex retainers in vivo. MATERIALS AND METHODS MRI scans (3 Tesla) were performed on a male volunteer with different CAD/CAM retainers (cobalt-chromium, CoCr; nickel-titanium, NiTi; grade 5 titanium, Ti5) and twistflex retainers inserted. A total of 126 landmarks inside and outside the retainer area (RA; from canine to canine) were evaluated by two blinded radiologists using an established five-point visibility scoring (1: excellent, 2: good, 3: moderate, 4: poor, 5: not visible). Friedman and two-tailed Wilcoxon tests were used for statistical analysis (significance level: p < 0.05). RESULTS Twistflex retainers had the strongest impact on the visibility of all landmarks inside (4.0 ± 1.5) and outside the RA (1.7 ± 1.2). In contrast, artefacts caused by CAD/CAM retainers were limited to the dental area inside the RA (CoCr: 2.2 ± 1.2) or did not impair MRI-based diagnostics in a clinically relevant way (NiTi: 1.0 ± 0.1; Ti5: 1.4 ± 0.6). CONCLUSION The present study on a single test person demonstrates that conventional stainless steel twistflex retainers can severely impair the diagnostic value in head/neck and dental MRI. By contrast, CoCr CAD/CAM retainers can cause artefacts which only slightly impair dental MRI but not head/neck MRI, whereas NiTi and Ti5 CAD/CAM might be fully compatible with both head/neck and dental MRI.
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Affiliation(s)
- Christoph J Roser
- Department of Orthodontics and Dentofacial Orthopedics, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
| | - Tim Hilgenfeld
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Muhammad Abdullah Saleem
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Thomas Rückschloß
- Department of Oral and Maxillofacial Surgery, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Sabine Heiland
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Martin Bendszus
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Christopher J Lux
- Department of Orthodontics and Dentofacial Orthopedics, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Alexander Juerchott
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
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7
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Hegde S. ARTIFACTS IN MAGNETIC RESONANCE IMAGING CAUSED BY DENTAL MATERIALS: A SYSTEMATIC REVIEW. J Evid Based Dent Pract 2022; 22:101754. [DOI: 10.1016/j.jebdp.2022.101754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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8
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Bohner L, Hanisch M, Sesma N, Blanck-Lubarsch M, Kleinheinz J. Artifacts in magnetic resonance imaging caused by dental materials: a systematic review. Dentomaxillofac Radiol 2022; 51:20210450. [PMID: 35348371 PMCID: PMC10043623 DOI: 10.1259/dmfr.20210450] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 03/07/2022] [Accepted: 03/09/2022] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The purpose of this systematic review was to search in literature in which severity unintended effects are caused by dental materials in magnetic resonance imaging (MRI), such as to evaluate whether these artifacts hamper the diagnosis in the head and neck region. MATERIALS AND METHODS Clinical studies showing the severity of artifacts which dental materials are capable of causing in MRI of head and neck, such as their influence on diagnostic accuracy, were included in this review. The searches were conducted in four electronic databases (PubMed/Medline, Embase, Scopus and Web of Science), and a manual search was made in the reference lists of papers screened for full-text reading. Risk of bias was assessed using "Quality Assessment Tool for Diagnostic Accuracy Studies-2" (QUADAS-2). The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to assess the quality of evidence. RESULTS From 151 studies selected for full-reading, 19 were considered eligible for this review. Artifacts caused by orthodontic appliances were well-documented, and stainless steel brackets were the materials most likely to cause artifacts in MR imaging of head and neck. The literature was scarce for dental implants and restorations. Diagnoses within the oral cavity, but also those of the brain and craniofacial structures, were affected. CONCLUSION Artifacts caused by orthodontic appliances may affect the diagnosis in oral cavity and craniofacial structures. Data regarding dental implants and prosthodontics restorations were inconclusive. The severity of artifacts in MRI and their influence on diagnosis is dependent on dental material features, location in the oral cavity, and magnetic resonance parameters.
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Affiliation(s)
- Lauren Bohner
- Department of Cranio-Maxillofacial Surgery, University Hospital Muenster, Muenster, Germany
| | - Marcel Hanisch
- Department of Cranio-Maxillofacial Surgery, University Hospital Muenster, Muenster, Germany
| | - Newton Sesma
- Department of Prosthodontics, School of Dentistry, University of São Paulo, São Paulo, Brazil
| | | | - Johannes Kleinheinz
- Department of Cranio-Maxillofacial Surgery, University Hospital Muenster, Muenster, Germany
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9
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Ashok A, Ayyadanveettil P, Devarajan E, Thavakkara V, Latha N, Saraswathy A. The effect of metallic dental restorations and implants in causing patient discomfort and artefacts during magnetic resonance imaging of the head and neck. Indian J Dent Res 2022; 33:258-262. [PMID: 36656184 DOI: 10.4103/ijdr.ijdr_430_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Context Patients with metallic dental objects in their oral cavity are often associated with discomfort or artefacts during magnetic resonance imaging (MRI) of the head and neck. Aim This study was conducted to evaluate the effects of metallic dental objects in causing patient discomfort and artefacts during MRI of the head and neck region. Design This is an observational study including 538 participants from various specialized MRI centres in Kozhikode. Methods and Material MRI records of 538 participants who underwent head and neck MRI as a part of their medical treatment were collected. With the help of questionnaire and clinical examination, the type of metallic dental object in the patient's oral cavity was identified. After examining the MRI images, four categories of artefacts were established. In MRI brain, artefacts in three different sequences were also studied. Statistical Analysis Used The significance of the difference between proportions was analysed by the Chi-square test. Results Artefacts were found in 65 cases with metallic dental objects but none of the participants had experienced any kind of discomfort. The artefact formation significantly depended on the type of metallic dental restoration in the patient's oral cavity. Orthodontic braces and titanium bone plate created severe artefacts in head and neck MRI making interpretation almost impossible. In the MRI brain, diffusion-weighted imaging is most sensitive to artefact followed by fluid-attenuated inversion recovery. Conclusions Artefacts were found in 65 cases with metallic dental restorations but none of the participants had experienced any kind of discomfort.
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Affiliation(s)
- Aiswarya Ashok
- Department of Prosthodontics, Government Dental College, Affiliated to Kerala University of Health Sciences, Kozhikode, Kerala, India
| | - Pramodkumar Ayyadanveettil
- Department of Prosthodontics, Government Dental College, Affiliated to Kerala University of Health Sciences, Kozhikode, Kerala, India
| | - Ellezhuthil Devarajan
- Department of Radiodiagnosis, Government Medical College, Affiliated to Kerala University of Health Sciences, Kozhikode, Kerala, India
| | - Vinni Thavakkara
- Department of Prosthodontics, Government Dental College, Affiliated to Kerala University of Health Sciences, Kozhikode, Kerala, India
| | - Neethu Latha
- Department of Prosthodontics, Government Dental College, Affiliated to Kerala University of Health Sciences, Kozhikode, Kerala, India
| | - Arya Saraswathy
- Department of Prosthodontics, Government Dental College, Affiliated to Kerala University of Health Sciences, Kozhikode, Kerala, India
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10
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Blankenstein FH, Kielburg U, Melerowitz L, Stelmaszczyk D. The intraoral permeability measurement as a screening for artifact formation by orthodontic products in MRI. J Orofac Orthop 2021:10.1007/s00056-021-00360-9. [PMID: 34738142 DOI: 10.1007/s00056-021-00360-9] [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: 12/02/2020] [Accepted: 09/22/2021] [Indexed: 10/19/2022]
Abstract
AIM Metal dental products lack precautionary statements regarding MR compatibility due to an exemption in the labelling obligation. Hence, it is difficult for radiologists to decide whether to remove fixed metal objects in patients prior to MRI. A solution could be the direct determination of the magnetic permeability (µr) as a decisive material-related predictor of artifact formation and other interactions. Thus, the applicability of an industrially used measurement device as a screening instrument and the relevance of the manufacturer's application restrictions in vitro and in vivo were tested. METHODS Precision and trueness were tested using self-made test objects with different dimensions and different permeability. To clarify whether the measurement results are affected by the remanence (BR) induced in the objects, 28 brackets of different materials were exposed to a weak and a strong external magnetic field and the magnetic flux density before and after these exposures was compared. The clinical test was performed on a volunteer with an orthodontic appliance experimentally composed of brackets with different levels of magnetic permeability (µr). Validity and intra- and interrater reliability were calculated using two rater groups consisting of four dentists and four medical-technical radiology assistants (MTRA), respectively. RESULTS With coefficients of variation below 0.14%, precision was excellent regardless of object surface and size. Trueness was high on objects with µr ≤ 1.002, and decreased with increasing µr, for which size-dependent correction factors were calculated. Intra- and interrater reliability and validity were excellent and independent of professional intraoral manipulation experience. CONCLUSIONS The permeability measurement allows for a valid and reliable determination of the magnetizability of intraoral metal objects. When used as a screening tool to detect nonartifact-causing objects, no correction factor needs to be calculated. For the first time, it offers radiologists a decision support for the selective removal of only the highly permeable components of the multiband apparatus.
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Affiliation(s)
- Felix H Blankenstein
- Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Aßmannshauser Str. 4-6, 14197, Berlin, Germany.
| | - Ulrike Kielburg
- Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Aßmannshauser Str. 4-6, 14197, Berlin, Germany
| | - Ludwig Melerowitz
- Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Aßmannshauser Str. 4-6, 14197, Berlin, Germany
| | - Daniel Stelmaszczyk
- Branch office Stendal, Clinic for Radio oncology, Johanniter Ltd., Wendstraße 31, 39576, Stendal, Germany
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11
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Chi JM, Hagiwara M. Update on MRI for Oral Cavity. Top Magn Reson Imaging 2021; 30:85-96. [PMID: 33828060 DOI: 10.1097/rmr.0000000000000278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
ABSTRACT Magnetic resonance imaging (MRI) is the imaging modality of choice to evaluate the complex anatomy and pathology of the oral cavity. In this article, an overview of MRI findings of common benign lesions in the oral cavity including congenital, vascular, and inflammatory/infectious lesions will be reviewed. In addition, MRI findings of common benign and malignant oral cavity tumors will be presented.
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Affiliation(s)
- Joan M Chi
- Department of Radiology, NYU Langone Health, New York, NY
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12
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Sonesson M, Al-Qabandi F, Månsson S, Abdulraheem S, Bondemark L, Hellén-Halme K. Orthodontic appliances and MR image artefacts: An exploratory in vitro and in vivo study using 1.5-T and 3-T scanners. Imaging Sci Dent 2021; 51:63-71. [PMID: 33828963 PMCID: PMC8007402 DOI: 10.5624/isd.20200199] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/25/2020] [Accepted: 10/14/2020] [Indexed: 11/18/2022] Open
Abstract
Purpose The aim of this study was to assess the artefacts of 12 fixed orthodontic appliances in magnetic resonance images obtained using 1.5-T and 3-T scanners, and to evaluate different imaging sequences designed to suppress metal artefacts. Materials and Methods In vitro, study casts of 1 adult with normal occlusion were used. Twelve orthodontic appliances were attached to the study casts and scanned. Turbo spin echo (TSE), TSE with high readout bandwidth, and TSE with view angle tilting and slice encoding for metal artefact correction were used to suppress metal artefacts. Artefacts were measured. In vivo, 6 appliances were scanned: 1) conventional stainless-steel brackets; 2) nickel-free brackets; 3) titanium brackets; 4) a Herbst appliance; 5) a fixed retainer; and 6) a rapid maxillary expander. The maxilla, mandible, nasopharynx, tongue, temporomandibular joints, and cranial base/eye globes were assessed. Scores of 0, 1, 2, and 3 indicated no artefacts and minor, moderate, and major artefacts, respectively. Results In vitro, titanium brackets and the fixed retainer created minor artefacts. In vivo, titanium brackets caused minor artefacts. Conventional stainless-steel and nickel free brackets, the fixed retainer, and the rapid maxillary expander caused major artefacts in the maxilla and mandible. Conventional stainless-steel and nickel-free brackets caused major artefacts in the eye globe (3-T). TSE with high readout bandwidth reduced image artefacts in both scanners. Conclusion Titanium brackets, the Herbst appliance, and the fixed retainer caused minor artefacts in images of neurocranial structures (1.5-T and 3-T) when using TSE with high readout bandwidth.
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Affiliation(s)
- Mikael Sonesson
- Department of Orthodontics, Faculty of Odontology, Malmö University, Malmö, Sweden
| | - Fahad Al-Qabandi
- Department of Orthodontics, Faculty of Odontology, Malmö University, Malmö, Sweden
| | - Sven Månsson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Salem Abdulraheem
- Department of Orthodontics, Faculty of Odontology, Malmö University, Malmö, Sweden.,Department of Orthodontics, Al-Jahra Specialty Dental Center, Ministry of Health, Kuwait, Sweden
| | - Lars Bondemark
- Department of Orthodontics, Faculty of Odontology, Malmö University, Malmö, Sweden
| | - Kristina Hellén-Halme
- Department of Oral and Maxillofacial Radiology, Faculty of Odontology, Malmö University, Malmö, Sweden
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Alawsi F, Sawbridge D, Fitzgerald R. Orthodontics in patients with significant medical co-morbidities. J Orthod 2020; 47:4-24. [PMID: 32985344 DOI: 10.1177/1465312520949881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A wide variety of patients with medical co-morbidities may present to general orthodontic practice. It is important for the treating clinician to have a general understanding of key medical conditions that may impact upon the treatment and management options. This clinical supplement provides a treatment-focused summative update for the orthodontist regarding significant medical co-morbidities, their general prevalence and an exploration of potential impacts upon orthodontic treatment. This review also discusses the significance of key medications and provides suggestions for the safe provision of orthodontic treatment.
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Affiliation(s)
- Fahad Alawsi
- Orthodontic Department, Royal Preston Hospital, Preston, UK
| | - David Sawbridge
- Intestinal Failure Unit, Salford Royal NHS Foundation Trust, Salford, UK
| | - Rhian Fitzgerald
- Orthodontic Department, Royal Preston Hospital, Preston, UK.,Alder Hey Children's Hospital, Liverpool, UK
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14
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Magnetic Resonance Imaging and Its Effects on Metallic Brackets and Wires: Does It Alter the Temperature and Bonding Efficacy of Orthodontic Devices? MATERIALS 2019; 12:ma12233971. [PMID: 31801202 PMCID: PMC6926903 DOI: 10.3390/ma12233971] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 11/25/2019] [Accepted: 11/27/2019] [Indexed: 12/02/2022]
Abstract
Magnetic resonance imaging (MRI) is a widely used diagnostic technique. Patients wearing orthodontic appliances are often requested to remove their appliances, even when the MRI exam involves anatomical areas far from mouth, in order to avoid heating of the metal and detachment of the appliance. The purpose of the present investigation was to measure and compare temperature changes and orthodontic appliances’ adhesion to enamel after different MRIs. A total of 220 orthodontic brackets were bonded on bovine incisors and wires with different materials (stainless steel and nickel titanium). Moreover, various sizes (0.014″ and 0.019″ × 0.025″) were engaged. Appliances were submitted to MRI at two different powers (1.5 T and 3 T). The temperatures of brackets and wires were measured before and after MRI. Subsequently, the shear bond strength (SBS) and adhesive remnant index (ARI) scores were recorded. Statistical analysis was performed. After MRI, a significant increase in the temperature was found for both the brackets and wires in some groups, even if the mean temperature increase was clinically insignificant, as the temperature ranged between 0.05 °C and 2.4 °C for brackets and between 0.42 °C and 1.74 °C for wires. The MRI did not condition bracket adhesion in any group. No differences were reported when comparing the 1.5 T with 3 T groups. The ARI Scores were also significantly lower after MRI. The results of the present report show that, under MRI, orthodontic appliances present a low temperature rise and no debonding risk. Therefore, the removal of orthodontic appliance is not recommended routinely, but is suggested only in the case of a void risk or potential interference in image quality.
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[Metal objects of the head and neck region in magnetic resonance imaging : Survey among radiologists]. Radiologe 2019; 59:906-911. [PMID: 31444511 DOI: 10.1007/s00117-019-00589-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
CONTEXT Although in recent times more research has been done on interactions of metallic dental objects in magnetic resonance imaging (MRI), radiologists are often uncertain whether the objects should be removed or can be retained prior to an impending examination. On the one hand, they want to avoid unnecessary material removal which is associated with costs and potential damage of the dental object. On the other hand, they fear material-induced susceptibility artefacts will impair the diagnostic workup so that examinations will have to be repeated. The lack of information complicates adequate decision making for radiologists. AIM The aim of this survey was to evaluate the information that is currently available to radiologists regarding orthodontic appliances of the head and neck region in the MRI and determine how to handle these situations in a radiologist's every day routine. Therefore, this study can reveal the need for further research. MATERIALS AND METHODS The questionnaire was published in the 9/2017 issue of the journal Der Radiologe and sent as an electronic version by the BDR (Professional Association of German Radiologists) to their approximately 1800 members. In addition, the radiological institutes of 55 German university and maximum care clinics were contacted. RESULTS In all, 74 evaluable responses were received within a period of 16 weeks, representing a response rate of 3.7%. Altogether, the participants rate the risks of a detachment or heating of orthodontic appliances as too high. The interviewed radiologists categorize the available data as insufficient and they almost unanimously (97.3%) demand a declaration requirement for the manufacturers. There is a clear need for further education (78.3%). Intraoral measurement of the magnetic permeability is considered as a useful tool to determine possible interactions with the MRI by 40.5%.
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Effects of orthodontic appliances on the diagnostic capability of magnetic resonance imaging in the head and neck region: A systematic review. Int Orthod 2019; 17:403-414. [PMID: 31285157 DOI: 10.1016/j.ortho.2019.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES Patients in active fixed orthodontic treatment or fixed retention phase may require magnetic resonance (MR) scans of the head and neck region. Orthodontists are challenged to decide whether to keep or remove orthodontic appliances prior to the scans. The aim of this study was to determine the effect of orthodontic appliances on the diagnostic capability of MR images. METHODS Four electronic databases were searched, with no language restrictions, from database inception to October 2016: PubMed, EMBASE, CINAHL, EBMR. A search in Google Scholar and ProQuest, as well as a manual search, were also conducted. Two independent reviewers assessed articles for inclusion. Original studies including any orthodontic appliance on human subjects were considered. Outcomes measured were development of artefacts, diagnostic quality, accuracy, and treatment outcomes. Risk of bias was assessed with the Cochrane Risk of Bias Assessment and QUADAS-2 tools. RESULTS Five of 1052 studies identified were included in the final qualitative synthesis. A total of 90 adult human subjects were included. Orthodontic appliances evaluated were brackets, bands, archwires, and fixed retainers. The outcomes assessed were production of artefacts, diagnostic quality and diagnostic accuracy. Detrimental effects on diagnostic quality, and subsequently diagnostic accuracy, rose with increased stainless steel (SS) and proximity to anatomic area of interest. Orthodontic appliances may render images uninterpretable and non-diagnostic. CONCLUSIONS There is fair evidence to suggest orthodontic appliances, mainly those with SS, cause MR artefacts. Removal of metal orthodontic appliances prior to MR scans is recommended, especially if the area of interest is near the orthodontic appliance. Additional evidence is needed to provide guidelines to clinicians.
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Chockattu SJ, Suryakant DB, Thakur S. Unwanted effects due to interactions between dental materials and magnetic resonance imaging: a review of the literature. Restor Dent Endod 2018; 43:e39. [PMID: 30483463 PMCID: PMC6237727 DOI: 10.5395/rde.2018.43.e39] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 06/25/2018] [Indexed: 12/20/2022] Open
Abstract
Magnetic resonance imaging (MRI) is an advanced diagnostic tool used in both medicine and dentistry. Since it functions based on a strong uniform static magnetic field and radiofrequency pulses, it is advantageous over imaging techniques that rely on ionizing radiation. Unfortunately, the magnetic field and radiofrequency pulses generated within the magnetic resonance imager interact unfavorably with dental materials that have magnetic properties. This leads to unwanted effects such as artifact formation, heat generation, and mechanical displacement. These are a potential source of damage to the oral tissue surrounding the affected dental materials. This review aims to compile, based on the current available evidence, recommendations for dentists and radiologists regarding the safety and appropriate management of dental materials during MRI in patients with orthodontic appliances, maxillofacial prostheses, dental implants, direct and indirect restorative materials, and endodontic materials.
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Affiliation(s)
- Sherin Jose Chockattu
- Department of Conservative Dentistry & Endodontics, Bapuji Dental College & Hospital, Davangere, KA, India
| | - Deepak Byathnal Suryakant
- Department of Conservative Dentistry & Endodontics, Dental College, Regional Institute of Medical Sciences, Imphal, MN, India
| | - Sophia Thakur
- Department of Conservative Dentistry & Endodontics, Bapuji Dental College & Hospital, Davangere, KA, India
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Ozawa E, Honda EI, Parakonthun KN, Ohmori H, Shimazaki K, Kurabayashi T, Ono T. Influence of orthodontic appliance-derived artifacts on 3-T MRI movies. Prog Orthod 2018; 19:7. [PMID: 29457192 PMCID: PMC5817053 DOI: 10.1186/s40510-018-0204-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/15/2018] [Indexed: 11/22/2022] Open
Abstract
Background Magnetic resonance imaging (MRI) has been used to study configurations of speech organs in the resting state. However, MRI is sensitive to metals, and numerous types of metallic appliances, most of which have a large magnetic susceptibility, are used in orthodontic treatment and may cause severe artifacts on MRI. We have developed techniques for obtaining MRI movies of the oral region, to evaluate articulatory changes, especially movement of the tongue, palate, and teeth, pre- and post-orthodontic/orthognathic treatment. We evaluated the influence of artifacts caused by orthodontic appliances, including fixed retainers, metal brackets, and wires, on measurements in 3-T MRI movies. Methods Sixteen healthy young adults (nine males, seven females; average age, 27 years) with normal occlusion were recruited. Four types of customized maxillary and mandibular plates were prepared by incorporating one of the following into the plate: (a) nothing, (b) a fixed canine-to-canine retainer, (c) metal brackets for the anterior and molar teeth, or (d) clear brackets for the anterior teeth and metal brackets for molars. A 3-T MRI movie, in segmented cine mode, was generated for each plate condition while participants pronounced a vowel-consonant-vowel syllable (/asa/). The size of the artifact due to the metallic brackets was measured. The face size and orthodontically important anatomical structures, such as the velum, the hard palate, and the laryngeal ventricle, were also measured. Results A large artifact was observed over the entire oral region around orthodontic appliances, altering regional visibility. The velopharyngeal height was measured as significantly longer in the presence of metal brackets. The maximum artifact size due to a metallic bracket was > 8 cm. Our results show that even if it is possible to obtain the measurements of palate length, nasion to sella, and nasion to basion in individuals wearing metal brackets for molars, the measurements might be affected due to the presence of artifacts. Conclusions Orthodontic appliances, including metallic materials, sometimes produce significant measurement error in speech evaluation using MRI movies, which often become invisible or distorted by metallic orthodontic appliances. When the distorted image is measured, caution should be exercised, as the measurement may be affected. Based on the study, it is concluded that orthodontists should not necessarily remove all metallic appliances before MRI examination because the influence varies among the appliances and should also know that a significant measurement error in speech evaluation using MRI movie may occur by image distortion caused by metallic artifacts.
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Affiliation(s)
- Erika Ozawa
- Department of Orthodontic Science, Tokyo Medical and Dental University (TMDU) Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
| | - Ei-Ichi Honda
- Department of Oral and Maxillofacial Radiology, The University of Tokushima, Tokushima, Japan
| | | | - Hiroko Ohmori
- Department of Orthodontic Science, Tokyo Medical and Dental University (TMDU) Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Kazuo Shimazaki
- Department of Orthodontic Science, Tokyo Medical and Dental University (TMDU) Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Tohru Kurabayashi
- Department of Oral and Maxillofacial Radiology, Tokyo Medical and Dental University (TMDU) Graduate School, Tokyo, Japan
| | - Takashi Ono
- Department of Orthodontic Science, Tokyo Medical and Dental University (TMDU) Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
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20
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Hayashi N, Ogura A, Tsuchihashi T, Takahashi D, Matsuda T, Seino S, Doi T. Magnetization and demagnetization of magnetic dental attachments in a 3-T MRI system. Radiol Phys Technol 2017; 10:294-300. [DOI: 10.1007/s12194-017-0399-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 04/20/2017] [Accepted: 04/23/2017] [Indexed: 10/19/2022]
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21
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Cassetta M, Pranno N, Stasolla A, Orsogna N, Fierro D, Cavallini C, Cantisani V. The effects of a common stainless steel orthodontic bracket on the diagnostic quality of cranial and cervical 3T- MR images: a prospective, case-control study. Dentomaxillofac Radiol 2017; 46:20170051. [PMID: 28452576 DOI: 10.1259/dmfr.20170051] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES To evaluate the effect of orthodontic stainless steel brackets and two different types of archwires on the diagnostic quality of 3-T MR images. METHODS This prospective, case-control study was conducted following Strengthening the Reporting of Observational Studies in Epidemiology guidelines. The recruitment was conducted among orthodontic patients. 80 subjects, requiring MRI for the presence of temporomandibular disorders, were enrolled and divided into four groups: 20 patients using aligners (control group); 20 patients with stainless steel brackets without archwires; 20 patients with stainless steel brackets and nickel-titanium archwires; and 20 patients with stainless steel brackets and stainless steel archwires. Two experts in neuroradiology evaluated the images to determine the amount of distortion in 6 regions and 48 districts. A score was subjectively assigned according to a modified receiver operating characteristic method of distortion classification. Any disagreement was resolved through consensus seeking; when this was not possible, a third neuroradiologist was consulted. The following statistical methods were used: descriptive statistics, Cohen's kappa coefficient (k), Kruskal-Wallis test, pairwise comparisons using the Dunn-Bonferroni approach. The significance was set at p ≤ 0.05. RESULTS The presence of stainless steel brackets with or without archwires negatively influenced MRI of the cervical region, paranasal sinuses, head and neck region, and cervical vertebrae but did not influence MRI of brain and temporomandibular joint regions. CONCLUSIONS Patients with a stainless steel multibracket orthodontic appliance should remove it before cervical vertebrae, cervical region, paranasal sinuses, and head and neck MRI scans. The brain and temporomandibular joint region MRI should not require the removal of such appliances.
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Affiliation(s)
- Michele Cassetta
- 1 Department of Oral and Maxillo-Facial Sciences, "Sapienza", University of Rome, Rome, Italy
| | - Nicola Pranno
- 1 Department of Oral and Maxillo-Facial Sciences, "Sapienza", University of Rome, Rome, Italy
| | | | - Nicola Orsogna
- 3 Department of Radiology, Oncology and Anatomy Pathology, "Sapienza", University of Rome, Rome, Italy
| | - Davide Fierro
- 3 Department of Radiology, Oncology and Anatomy Pathology, "Sapienza", University of Rome, Rome, Italy
| | - Costanza Cavallini
- 3 Department of Radiology, Oncology and Anatomy Pathology, "Sapienza", University of Rome, Rome, Italy
| | - Vito Cantisani
- 3 Department of Radiology, Oncology and Anatomy Pathology, "Sapienza", University of Rome, Rome, Italy
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22
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Jungmann PM, Agten CA, Pfirrmann CW, Sutter R. Advances in MRI around metal. J Magn Reson Imaging 2017; 46:972-991. [PMID: 28342291 DOI: 10.1002/jmri.25708] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 03/03/2017] [Indexed: 01/02/2023] Open
Abstract
The prevalence of orthopedic metal implants is continuously rising in the aging society. Particularly the number of joint replacements is increasing. Although satisfying long-term results are encountered, patients may suffer from complaints or complications during follow-up, and often undergo magnetic resonance imaging (MRI). Yet metal implants cause severe artifacts on MRI, resulting in signal-loss, signal-pileup, geometric distortion, and failure of fat suppression. In order to allow for adequate treatment decisions, metal artifact reduction sequences (MARS) are essential for proper radiological evaluation of postoperative findings in these patients. During recent years, developments of musculoskeletal imaging have addressed this particular technical challenge of postoperative MRI around metal. Besides implant material composition, configuration and location, selection of appropriate MRI hardware, sequences, and parameters influence artifact genesis and reduction. Application of dedicated metal artifact reduction techniques including high bandwidth optimization, view angle tilting (VAT), and the multispectral imaging techniques multiacquisition variable-resonance image combination (MAVRIC) and slice-encoding for metal artifact correction (SEMAC) may significantly reduce metal-induced artifacts, although at the expense of signal-to-noise ratio and/or acquisition time. Adding advanced image acquisition techniques such as parallel imaging, partial Fourier transformation, and advanced reconstruction techniques such as compressed sensing further improves MARS imaging in a clinically feasible scan time. This review focuses on current clinically applicable MARS techniques. Understanding of the main principles and techniques including their limitations allows a considerate application of these techniques in clinical practice. Essential orthopedic metal implants and postoperative MR findings around metal are presented and highlighted with clinical examples. LEVEL OF EVIDENCE 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:972-991.
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Affiliation(s)
- Pia M Jungmann
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Faculty of Medicine, University of Zurich, Zurich, Switzerland.,Department of Radiology, Technical University of Munich, Munich, Germany
| | - Christoph A Agten
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Faculty of Medicine, University of Zurich, Zurich, Switzerland
| | - Christian W Pfirrmann
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Department of Radiology, Technical University of Munich, Munich, Germany
| | - Reto Sutter
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Department of Radiology, Technical University of Munich, Munich, Germany
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Magnetic permeability as a predictor of the artefact size caused by orthodontic appliances at 1.5 T magnetic resonance imaging. Clin Oral Investig 2016; 21:281-289. [PMID: 26984824 DOI: 10.1007/s00784-016-1788-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 03/07/2016] [Indexed: 10/22/2022]
Abstract
OBJECTIVES Artefacts caused by orthodontic attachments limit the diagnostic value and lead to removal of these appliances before magnetic resonance imaging. Magnetic permeability can predict the artefact size. There is no standardised approach to determine the permeability of such attachments. The aim was to establish a reliable approach to determine artefact size caused by orthodontic attachments at 1.5 T MRI. MATERIALS AND METHODS Artefact radii of 21 attachments were determined applying two prevalent sequences of the head and neck region (turbo spin echo and gradient echo). The instrument Ferromaster (Stefan Mayer Instruments, Dinslaken) is approved for permeability measurements of objects with a minimum size (d = 20 mm, h = 5 mm). Eleven small test specimens of known permeability between 1.003 and 1.431 were produced. They are slightly larger than the orthodontic attachments. Their artefacts were measured and cross tabulated against the permeability. The resulting curve was used to compare the orthodontic attachments with the test bodies. RESULTS Steel caused a wide range of artefact size of 10-74 mm subject to their permeability. Titanium, cobalt-chromium and ceramic materials produced artefact radii up to 20 mm. Measurement of artefacts of the test bodies revealed an interrelationship according to a root function. The artefact size of all brackets was below that root function. CONCLUSIONS The permeability can be reliably assessed by conventional measurement devices and the artefact size can be predicted. The radiologist is able to decide whether or not the orthodontic attachments should be removed. CLINICAL RELEVANCE This study clarifies whether an orthodontic appliance must be removed before taking an MRI.
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Wang ZJ, Rollins NK, Liang H, Park YJ. Induced magnetic moment in stainless steel components of orthodontic appliances in 1.5 T MRI scanners. Med Phys 2015; 42:5871-8. [PMID: 26429261 DOI: 10.1118/1.4930796] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Most orthodontic appliances are made of stainless steel materials and induce severe magnetic susceptibility artifacts in brain MRI. In an effort for correcting these artifacts, it is important to know the value of induced magnetic moments in all parts of orthodontic appliances. In this study, the induced magnetic moment of stainless steel orthodontic brackets, molar bands, and arch-wires from several vendors is measured. METHODS Individual stainless steel brackets, molar bands, and short segments of arch-wire were positioned in the center of spherical flask filled with water through a thin plastic rod. The induced magnetic moment at 1.5 T was determined by fitting the B0 map to the z-component of the magnetic dipole field using a computer routine. RESULTS The induced magnetic moment at 1.5 T was dominated by the longitudinal component mz, with a small contribution from the transverse components. The mz was insensitive to the orientation of the metal parts. The orthodontic brackets collectively dominated the magnetic dipole moment in orthodontic appliances. In brackets from six vendors, the total induced mz from 20 brackets for nonmolar teeth ranged from 0.108 to 0.158 (median 0.122) A ⋅ m(2). The mz in eight molar bands with bracket attachment from two vendors ranged from 0.0004 to 0.0166 (median 0.0035) A ⋅ m(2). Several full length arch wires had induced magnetic moment in the range of 0.006-0.025 (median 0.015) A ⋅ m(2). CONCLUSIONS Orthodontic brackets collectively contributed most to the total magnetic moment. Different types of brackets, molar bands, and arch wires all exhibit substantial variability in the induced magnetic moment.
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Affiliation(s)
- Zhiyue J Wang
- Department of Radiology, Children's Medical Center, Dallas, Texas 75235 and Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Nancy K Rollins
- Department of Radiology, Children's Medical Center, Dallas, Texas 75235 and Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Hui Liang
- Baylor College of Dentistry, Texas A&M University, Dallas, Texas 75246
| | - Yong Jong Park
- Division of Orthodontics, Children's Medical Center, Dallas, Texas 75235
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25
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Zachriat C, Asbach P, Blankenstein KI, Peroz I, Blankenstein FH. MRI with intraoral orthodontic appliance-a comparative in vitro and in vivo study of image artefacts at 1.5 T. Dentomaxillofac Radiol 2015; 44:20140416. [PMID: 25734243 DOI: 10.1259/dmfr.20140416] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES We investigated artefacts caused from orthodontic appliances at 1.5-T MRI of the head and neck region and whether the image quality can be improved utilizing the artefact-minimizing sequence WARP. METHODS In vitro tests were performed by phantom measurements of different orthodontic devices applying different types of MR sequences [echoplanar imaging (EPI), turbo spin echo (TSE) and TSE-WARP, gradient echo (GRE)]. Two independent readers determined after calibration the level of artefacts. Subsequently, the interobserver agreement was calculated. The measurement of artefacts was based on the American Society for Testing Materials Standard F 2119-07. For in vivo imaging, one test person was scanned with an inserted multibracket appliance. The level of artefacts for 27 target regions was evaluated. RESULTS In vitro: ceramic brackets and ferromagnetic steel brackets produced artefact radii up to 1.12 and 7.40 cm, respectively. WARP reduced these artefacts by an average of 32.7%. The Bland-Altman-Plot indicated that maximum measurement differences of 3 mm have to be expected with two calibrated observers. In vivo: the EPI sequence for brain imaging was not analysable. The TSE sequence of the brain did not demonstrate artefacts except for the nasal cavity. Conversely, the TSE sequence of the cervical spine revealed severe artefacts in the midface region. The GRE sequence appeared to be more susceptible to artefacts than did the TSE sequence. CONCLUSIONS In vitro measurements allow an estimation of the in vivo artefact size. Orthodontic appliances may often remain intraorally when performing MRI. WARP showed a more significant effect in vitro than in vivo.
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Affiliation(s)
- C Zachriat
- 1 Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - P Asbach
- 2 Department of Radiology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
| | - K I Blankenstein
- 3 Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - I Peroz
- 1 Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - F H Blankenstein
- 1 Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité-Universitätsmedizin Berlin, Berlin, Germany
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