Dental fillings are safe to have during an MRI. They will not be pulled out of your teeth, and they won’t heat up enough to cause harm. However, certain filling materials can distort the images the MRI produces, which matters most when the scan targets your head, jaw, or neck.
Why Fillings Are Safe in the Scanner
The two main safety concerns with any metal inside an MRI are heating and physical movement. Both have been studied specifically for dental fillings, and neither poses a meaningful risk. In controlled testing of amalgam (silver) fillings, the temperature rise during a 1.5T MRI scan ranged from 0.21°C to 0.70°C, well below the 1°C safety limit set by the International Commission on Non-Ionizing Radiation Protection. Dental implants showed a similar result, averaging a 0.41°C increase. For context, pulp tissue damage doesn’t begin until temperatures rise by 5°C or more.
Physical displacement is also a non-issue. Fillings are small, and the magnetic force they experience is far too weak to move them. The American Society for Testing and Materials notes that the heating of metallic objects smaller than 2 cm is not clinically significant, and most fillings fall well within that size.
How Fillings Can Affect Image Quality
While fillings won’t hurt you, they can interfere with the pictures themselves. An MRI works by using a powerful, uniform magnetic field to detect signals from hydrogen atoms in your body. When a filling material has different magnetic properties than the surrounding tissue, it creates a mismatch at the boundary. That mismatch distorts the local magnetic field, which shifts the signal from nearby tissue and produces artifacts: dark voids, bright spots, or warped anatomy on the image.
This is called a susceptibility artifact, and its size depends on two things: how magnetic the filling material is, and how strong the MRI scanner is. Higher-strength scanners (3T versus 1.5T) amplify the distortion. The effect is localized to the area near the filling, so it primarily matters for scans of the head and neck. If you’re getting a knee MRI or a scan of your lower back, your dental work won’t affect the images at all.
Which Materials Cause the Most Distortion
Not all dental materials behave the same in an MRI. The differences are dramatic.
- Composite (tooth-colored) fillings, ceramic, and zirconia crowns produce virtually no artifacts. In one study, these materials were statistically indistinguishable from having no dental work at all.
- Gold and precious metal crowns also barely produced artifacts, making them MRI-friendly.
- Amalgam (silver) fillings contain a mix of metals and can cause moderate distortion in the surrounding area, though they remain safe.
- Nickel-chromium and cobalt-chromium crowns create the worst artifacts. In testing, double crowns made from these alloys increased the distorted area by roughly 150 to 175 square millimeters, enough to obscure nearby structures in a head or jaw scan.
- Titanium implants cause moderate distortion on their own, and the artifacts grow larger when combined with nickel, chromium, or cobalt-based crowns on top.
The key factor is a property called magnetic susceptibility. Nickel (600 ppm), chromium (320 ppm), and cobalt (250 ppm) are all strongly paramagnetic, meaning they interact heavily with the MRI’s magnetic field. The more of these metals in your dental work, the bigger the artifact.
What Your MRI Team Can Do About It
If you need a scan of your head or neck and have metal dental work, radiologists have specialized techniques to reduce the distortion. These include sequences with names like SEMAC (slice-encoding for metal artifact correction), MAVRIC, and MSVAT-SPACE. Each uses extra data collection steps to correct the warped signal near metal objects. SEMAC, for example, adds phase-encoding steps in the slice direction to fix distortions in the shape of each image slice, while also correcting for in-plane warping.
These techniques don’t eliminate artifacts entirely, but they can significantly improve image quality around dental hardware. Your radiologist will choose the right approach based on what type of scan you need and what area needs to be visualized clearly.
What to Tell Your MRI Facility
Before any MRI, you’ll be asked about metal in or on your body. Mention all dental work, including fillings, crowns, bridges, implants, and retainers. You don’t need to bring documentation for standard fillings. The screening is mainly to identify anything that could be unsafe (like certain older magnetic dental attachments) and to help the technologist plan for potential image artifacts.
If you know the specific materials in your dental work, sharing that information helps. Your dentist’s office can provide details if you’re unsure whether a crown contains nickel-chromium versus zirconia, for example. This is most useful when the MRI targets your jaw, sinuses, or brain, where nearby dental artifacts could overlap with the area being examined. For scans of other body parts, your fillings simply won’t matter.