Magnetic Resonance Imaging (MRI) is a powerful diagnostic tool that creates detailed images of organs, soft tissues, bone, and other internal body structures. A common question arises regarding the safety of undergoing an MRI scan when a person has dental fillings or other dental work. While this concern is understandable due to the strong magnetic fields involved, most modern dental fillings and restorations are generally not an issue for MRI procedures.
How MRI Technology Interacts with Dental Materials
MRI technology uses a strong magnetic field and radio waves to generate detailed images of the body’s internal structures. When a patient enters the MRI scanner, the magnetic field temporarily realigns the water molecules in the body, and radio waves are then pulsed to knock these aligned molecules out of position. As the molecules relax back into alignment, they emit signals that are detected by the MRI machine and converted into cross-sectional images.
Metal objects within this strong magnetic environment can interact in several ways, potentially posing a risk or affecting image quality. Ferromagnetic materials, like iron, nickel, or cobalt, are strongly attracted to the MRI magnet, which could cause them to move and pose a safety risk. Additionally, any conductive material can experience induced electrical currents when exposed to rapidly changing magnetic fields, which may lead to localized heating. These interactions are why thorough screening for metallic implants or foreign bodies is a standard part of MRI preparation.
Dental Materials and MRI Compatibility
Amalgam, often referred to as silver fillings, contains a mixture of metals including silver, tin, copper, and mercury. These fillings are generally considered safe for MRI scans because their metallic composition is not strongly ferromagnetic, making them unlikely to be pulled or moved by the magnetic field. While rare, they may cause a slight, localized temperature increase or minor image distortion (artifacts) near the filling, which typically does not affect patient safety or the diagnostic quality of the scan in distant areas.
Composite resin fillings, commonly known as white or tooth-colored fillings, are made from a blend of plastic and glass particles. Since these materials are non-metallic, they pose no issues with MRI procedures and are completely safe for scanning. Gold fillings and crowns, comprised primarily of gold, are also non-ferromagnetic and generally safe for MRI. Like amalgam, they might produce minimal image artifacts that could slightly obscure the immediate area around the restoration.
Other dental metals, such as titanium found in dental implants, are non-ferromagnetic and considered safe for MRI. Stainless steel, used in some crowns, retainers, or orthodontic braces, is generally safe and unlikely to move or heat significantly. However, these materials are more likely to cause noticeable image distortion (artifacts), which can appear as signal voids or bright spots and might obscure the area being scanned, potentially affecting the diagnostic utility of the image in that specific region.
Preparing for an MRI with Dental Work
Before undergoing an MRI, it is important to disclose all dental work to your healthcare providers, including the referring doctor and, critically, to the MRI technologist and staff. This includes fillings, crowns, bridges, implants, orthodontic braces, and retainers. Providing this information allows the MRI facility to assess potential risks and adjust scanning protocols if necessary.
Patients should complete all pre-screening questionnaires thoroughly and truthfully, as these are designed to identify any metallic objects that could interfere with the scan or pose a safety concern. If you are unsure about the specific materials in your dental work, consulting your dentist beforehand can be helpful, as they can provide details about the types of restorations you have. The diagnostic benefits of an MRI generally outweigh the minimal risks associated with most dental fillings, especially when proper screening procedures are diligently followed by both the patient and the medical staff.