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Title Metallic Orthodontic Appliances Should Be Removed Prior To MRI Imaging
Clinical Question Does the presence of metallic orthodontic appliances distort the MRI image quality sufficiently to warrant their removal prior to the scan or pose a safety hazard to the patient?
Clinical Bottom Line Both image distortion and patient safety should be considered. When the need for MRI imaging is anticipated, the orthodontist should consider using esthetic ceramic brackets or other nonmagnetic brackets. Prior to MRI scanning, removable appliances and ferromagnetic appliances such as stainless steel should be removed. Arch wires should be firmly attached to brackets with wire ligatures, and auxiliary parts should be carefully checked for sound attachment or removed prior to MRI imaging.
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 18929275Ellison/200910 subjects received 5 cranial MRI cranial scansscans Clinical Comparative Study
Key resultsSubjects received 5 cranial MRI scans at 1.5T while wearing Essix trays embedded with brackets made of plastic, ceramic, titanium, stainless steel, or control (Essix trays without brackets). Three neuroradiologists rated the images for distortion. The stainless steel brackets produced significantly more distortion (P<0.0001)than the other materials and rendered some regions of the images non-diagnostic.
#2) 16333793Kemper/200532 orthodontic brackets made of different materialsIn vitro study
Key resultsExposed 32 orthodontic brackets constructed of steel alloy, cobal-chromium alloy, ceramic, ceramic with steel slot, and titanium to MRI magnetic field at 3T. Eighteen (56%) of the brackets developed translational or rotational forces that exceeded safety standards set by the American Society for Testing and Materials (ASTM). Authors noted, however, that these forces are much lower than those typically required to dislodge a firmly bonded bracket.
#3) 16807699Kemper/200720 auxiliary orthodontic appliancesIn vitro study
Key resultsExposed 20 auxiliary orthodontic appliances (e.g., springs, Herbst appliance, lip bumper) to MRI forces at 1.5 and 3 T and recorded translational and rotational forces. At 1.5T, 65% of the tested devices were found to be “not MR safe”, and at 3T, 75% were “not MR safe” according to ASTM standards. The authors noted that the MRI forces typically were lower than those expected during oral function, but recommended that they be carefully inspected for secure attachment before scanning.
#4) 19300375Costa (2009)70 MRI scans displaying artifacts possibly due to dental materialsRetrospective Records Review
Key resultsAuthors identified 70 MRI scans of patients with epilepsy that contained artifacts possibly due to metallic dental materials. The images were viewed in three planes, and the artifacts were rated. Seventy-eight percent of the artifacts were associated with orthodontic appliances, 18% with dental implants, and 4% with gold crowns.
Evidence Search "Orthodontic Brackets"[Mesh] AND "Magnetic Resonance Imaging"[Mesh]
Comments on
The Evidence
The Ellison study used a novel method to simulate fixed appliances fabricated from various materials. Images were rated blindly for distortion by three neuroradiologists using standardized methods, and inter-rater agreement was acceptable. The two studies by Kemper, et al. are in vitro studies of dental materials; direct assessment of MRI forces applied to brackets bonded to patients is impossible. The studies are informative about possible risks. The record review by Costa is included because it suggests the possible rate that severe distortion may be introduced by orthodontic appliances in an actual clinical MRI series. The sample may not be representative and there is high risk of observer bias.
Applicability These findings are applicable to any patient scheduled for a MRI examination and who are undergoing treatment with metallic appliances. Radiologists and Orthodontists should be aware of the image distortion and possible safety risk of the presence of metallic orthodontic appliances associated with MRI examinations.
Specialty/Discipline (Oral Medicine/Pathology/Radiology) (Orthodontics)
Keywords orthodontics, orthodontic brackets, magnetic resonance imaging, MRI, diagnostic imaging, distortion
ID# 2166
Date of submission: 03/15/2012spacer
E-mail hatch@uthscsa.edu
Author John P. Hatch, PhD
Co-author(s) Stephen R. Matteson, DDS
Co-author(s) e-mail matteson@uthscsa.edu
Faculty mentor/Co-author
Faculty mentor/Co-author e-mail
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
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None available
Comments and Evidence-Based Updates on the CAT
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by Caitlyn Luther, Lena Al-Farra (San Antonio, TX) on 12/01/2017
A PubMed search was performed on November 27, 2017. An article published in 2017 by Casetta (PMID 28452576) was found and there is new research regarding the CAT conclusion. This study is a prospective, case-control study that found that the need for removing orthodontic appliances for MRI scans depends on the region being scanned. This research verifies that orthodontic appliances do affect MRI readings and should be removed, but only for certain regions. It found it is not necessary to remove orthodontic appliances for MRIs of the brain and TMJ since they have no effect on the imaging.

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