Magnetic Resonance Imaging (MRI) uses a strong magnetic field and radio waves to generate detailed cross-sectional images of organs and soft tissues inside the body. Braces are orthodontic devices, typically made of metal or non-metal components, used to align teeth and jaws. The presence of metallic materials in the powerful magnetic environment of an MRI machine is the primary concern for patients with braces. An MRI is generally possible with braces, but the final decision depends heavily on the specific material of the orthodontic device and the location of the body being scanned.
How Braces Affect MRI Scans
The fundamental interaction between the metal in braces and the MRI machine’s magnetic field creates two main issues: image distortion and, less commonly, safety concerns. The most common problem is the formation of image artifacts, which are signal distortions appearing as dark or bright streaks and blank spots on the final picture. These artifacts can obscure the surrounding anatomy, making the scan difficult or impossible for a radiologist to interpret accurately.
The severity of this distortion is directly related to the material used in the braces. Ferromagnetic materials, which are strongly attracted to magnets, cause the most significant image degradation. However, most modern orthodontic alloys, such as stainless steel and titanium, are now weakly or non-ferromagnetic. Even these materials disrupt the uniformity of the magnetic field, leading to a susceptibility artifact.
Safety concerns are typically minimal with contemporary braces. The radiofrequency pulses used by the MRI machine can cause a slight warming effect in the metal components of the braces. This is usually minimal, but patients are instructed to alert the technician if they feel any tingling or heat during the procedure. Modern stainless steel and titanium alloys are generally secured well enough to the teeth to be considered safe in standard scanners.
When Brace Removal is Necessary
The need to remove braces before an MRI is dependent on the proximity of the braces to the area being examined. For scans of the extremities, pelvis, or lower torso, the dental hardware is far enough away that the resulting image artifacts do not interfere with the diagnostic quality. In these cases, removal is unnecessary.
Brace removal, or temporary removal of components like the archwire, is a serious consideration for MRIs of the head, neck, brain, spine, or temporomandibular joint (TMJ). In these procedures, the artifacts generated by the metal directly overlap and obscure the tissues the doctor needs to see. For instance, a brain scan may be rendered unreadable if the metal distortion covers the target area.
The decision to proceed with removal is collaborative, involving the ordering physician, the radiologist, and the orthodontist. The orthodontist is responsible for the temporary removal and replacement of the brackets, which is a specialized procedure. If removal is required, the orthodontic treatment may be extended slightly, and there might be an additional fee for the de-bonding and re-bonding process.
Alternative Options for Patients with Braces
When a patient needs a clear image of their head or neck but cannot or chooses not to have their braces removed, several alternatives exist. The type of orthodontic material can significantly influence the image quality.
Material Alternatives
Ceramic or plastic brackets are non-metallic and cause far less signal distortion than traditional metal brackets, though the metal archwire may still generate some artifact. Specialized metal alloys like titanium, which is non-magnetic, also produce substantially fewer artifacts than traditional stainless steel. Patients with clear aligners, such as Invisalign, simply remove the plastic trays before the scan, as the aligners are entirely non-metallic.
Technical and Imaging Alternatives
Radiology centers can employ technical workarounds to minimize image distortion. Technicians may adjust the MRI sequence parameters, such as using specialized metal artifact reduction sequences. If an MRI is not absolutely necessary, alternative imaging modalities like a Computed Tomography (CT) scan or ultrasound may be considered, depending on the specific tissues the doctor needs to evaluate.