Influence of common fixed retainers on the diagnostic quality of cranial magnetic resonance images

The purpose of this study was to evaluate brain MRI distortion caused by orthodontic appliances. MRI was performed in 10 subjects and after insertion 3 kind of orthodontic appliances(type1-3), the MRI were compared. Type 1 used resin brackets in the incisor teeth, stainless steel brackets in the premolar teeth and stainless steel single tube in the molar teeth. Type2 used ceramic brackets in the incisor teeth, titanium brackets in the premolar teeth and titanium single tube in the molar teeth. Type3 used ceramic brackets with CoCr alloy clip in the incisor teeth, titanium brackets in the premolar teeth and titanium single tube in the molar teeth. Each MR sequence consisted of 6 sequences.: the Echo Planar Imaging method diffusion-weighted images(DWI), Spin Echo sequence(SE) T1-weighted images, Fast Field Echo sequence(FFE)T1-weighted images, Turbo Spin echo sequence(TSE)T2-weighted images, fat-supression image as Short Tau inversion recovery method(STIR), and Fluid attenuated-inversion recovery(FLAIR).Two neuro-surgeons examined the MRI for distortion in predetermined regions of the brain. In Type 1, MRI imaging by neither DWI nor FFE is feasible in these sites. SE-T1, TSE-T2, FLAIR and STIR are indicating the feasibility for MRI imaging. In Type 2 and Type 3, by all imaging types and at all of the anatomical sites, are indicating the feasibility for MRI imaging in the brain. The study showed that ceramic brackets, ceramic brackets with CoCr alloy clip, titanium brackets and titanium tubes do not always have to be removed before brain MRI.

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“…Inter-reviewer reliability was demonstrated by giving κ factors from scores rated by these two reviewers (18)(19)(20).…”

Section: Discussionmentioning

confidence: 99%

“…The assessment sites were defined at 8 sites, and rated as score for distortion by metal artifacts on MRI (Tables 4, 5) (18)(19)(20).…”

Section: Assessment Of Mrimentioning

confidence: 99%

Influence of Metal Artifact by Orthodontic Appliances on Brain MRI

et al. 2016

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“…Several studies of other appliances such as brackets or arches have already shown that stainless steel causes substantially larger artifacts than nickel–titanium or titanium [ 20 , 33 , 40 ]. One study analyzed MRI artifacts caused by a similar stainless-steel, triple-stranded Twistflex retainer [ 34 ]. It is important to note, however, that a different artifact quantification method was used in that study.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of magnetic resonance imaging artifacts caused by fixed orthodontic CAD/CAM retainers—an in vitro study

et al. 2020

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Objectives Magnetic resonance imaging (MRI) image quality can be severely impaired by artifacts caused by fixed orthodontic retainers. In clinical practice, there is a trend towards using computer-aided design/computer-aided manufacturing (CAD/CAM) retainers. This study aimed to quantify MRI artifacts produced by these novel CAD/CAM retainers. Material and methods Three CAD/CAM retainers and a stainless-steel retainer (“Twistflex”; clinical reference standard) were scanned in vitro at 3-T MRI using a high-resolution 3D sequence. The artifact diameters and three-dimensional artifact volumes (AV) were determined for all mandibular (AVmand) and maxillary (AVmax) retainers. Moreover, the corresponding ratio of artifact volume to retainer volume (AV/RVmand, AV/RVmax) was calculated. Results Twistflex caused large artifact volumes (AVmand: 13530 mm3; AVmax: 15642 mm3; AV/RVmand: 2602; AV/RVmax: 2235). By contrast, artifact volumes for CAD/CAM retainers were substantially smaller: whereas artifact volumes for cobalt–chromium retainers were moderate (381 mm3; 394 mm3; 39; 31), grade-5 titanium (110 mm3; 126 mm3; 12; 12) and nickel–titanium (54 mm3; 78 mm3; 12; 14) both produced very small artifact volumes. Conclusion All CAD/CAM retainers caused substantially smaller volumes of MRI artifacts compared to Twistflex. Grade-5 titanium and nickel–titanium CAD/CAM retainers showed the smallest artifact volumes. Clinical relevance CAD/CAM retainers made from titanium or nickel–titanium may not relevantly impair image quality in head/neck and dental MRI. Artifacts caused by cobalt–chromium CAD/CAM retainers may mask nearby dental/periodontal structures. In contrast, the large artifacts caused by Twistflex are likely to severely impair diagnosis of oral and adjacent pathologies.

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“…However, these devices can have a detrimental effect on the final image quality depending on the anatomical district being studied with the radiologic exam. A classification of dental materials according to their magnetic susceptibility has been proposed [33], and studies have evaluated the effects of orthodontic fixed metal appliances [34] and retainers [35] on image quality. There is fair evidence to suggest that orthodontic devices cause MRI image artefacts both at 1.5 T [8] and 3 T [36].…”

Section: Discussionmentioning

confidence: 99%

Magnetic Resonance Imaging and Its Effects on Metallic Brackets and Wires: Does It Alter the Temperature and Bonding Efficacy of Orthodontic Devices?

et al. 2019

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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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Influence of common fixed retainers on the diagnostic quality of cranial magnetic resonance images

Cited by 24 publications

References 14 publications

Influence of Metal Artifact by Orthodontic Appliances on Brain MRI

Influence of Metal Artifact by Orthodontic Appliances on Brain MRI

Evaluation of magnetic resonance imaging artifacts caused by fixed orthodontic CAD/CAM retainers—an in vitro study

Magnetic Resonance Imaging and Its Effects on Metallic Brackets and Wires: Does It Alter the Temperature and Bonding Efficacy of Orthodontic Devices?

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