A magnetic resonance imaging (MRI) scan uses a powerful magnetic field and radio waves to generate detailed images of the body’s internal structures. A dental bridge is a fixed prosthetic appliance used to replace one or more missing teeth. The presence of a dental bridge often raises questions about MRI safety because many bridges contain metal components. Generally, having a dental bridge does not prevent a patient from undergoing an MRI, but the material composition of the bridge is the primary factor determining compatibility and potential image quality issues.
The Materials That Matter
The interaction between a dental bridge and the MRI scanner is entirely dependent on the magnetic properties of the materials used in its construction. Ferromagnetic materials, which include iron, nickel, and cobalt alloys, are strongly attracted to the MRI magnet and are the most problematic. Older bridges or those made with less expensive alloys often contain these highly reactive materials, which can pose risks and cause significant image distortion. Conversely, many modern dental bridges use materials that are either non-ferromagnetic or only weakly magnetic. Non-ferromagnetic materials like porcelain, zirconia, and ceramic are completely safe, while paramagnetic materials such as gold alloys and titanium are generally safe due to their much weaker attraction to the magnetic field.
Safety Risks to the Patient
The main safety concerns for patients with metal-containing dental bridges during an MRI relate to the potential for heating and movement. Radiofrequency (RF) energy transmitted by the MRI can induce electrical currents in metallic implants, which may cause a temperature increase in the surrounding tissues. While this heating is generally mild for small, fixed devices like bridges, it remains a theoretical risk, particularly for older restorations or high-field MRI scanners. The risk of movement, or torque, is associated with ferromagnetic materials being pulled by the strong magnetic field of the scanner. Since dental bridges are small and securely cemented to the teeth, significant movement or damage to the oral tissue is extremely rare.
Understanding Image Interference
The most common practical issue caused by a metal dental bridge is image interference, known as an artifact. This occurs because the metal distorts the local magnetic field, which creates a signal void—a black spot—or streaking in the resulting image. This artifact can obscure the surrounding anatomy, making it difficult for the radiologist to accurately interpret the scan in that specific area. The severity of the image artifact depends on the magnetic susceptibility of the bridge material and the proximity of the bridge to the area being scanned. If the MRI is focused on the head, neck, or brain, a metal bridge can significantly compromise the diagnostic quality of the image, though it will have virtually no impact on an MRI of a distant body part.
Essential Steps Before Your MRI
Before undergoing an MRI, patients with a dental bridge should proactively inform the prescribing physician and the MRI technologist about their dental restoration. Screening questionnaires at the imaging center will always ask about metal implants, and it is important to be thorough and accurate in your response. Providing details about the bridge allows the radiology team to take necessary precautions, which may involve adjusting the scan parameters to minimize image distortion. If possible, the patient should try to identify the specific materials used in the bridge by contacting the dentist who placed it. Knowing the exact composition helps the technologist assess the risk of heating and the expected level of artifact, or suggest alternative imaging methods like a CT scan if the material is unknown.