Understanding MRI and Dental Materials
Magnetic Resonance Imaging (MRI) is a powerful and non-invasive diagnostic tool that utilizes strong magnetic fields and radiofrequency pulses to generate detailed images of the body’s internal structures. However, the presence of certain dental materials can interact with these magnetic fields, leading to potential safety concerns, including movement hazards, thermal effects, and image artifacts. Understanding these interactions is crucial for ensuring patient safety, preventing unnecessary risks, and obtaining accurate diagnostic images.
In this article, we will learn about MRI and dental materials, their interactions, safety concerns, and precautions for patients undergoing an MRI scan.
Interactions Between Dental Materials and MRI
Ferromagnetic Attraction
- Materials containing ferromagnetic metals (e.g., iron, nickel, cobalt) can experience strong attractive forces within the MRI’s magnetic field.
- This can lead to movement or displacement, posing risks to the patient.
- Stainless steel components in orthodontic appliances may be particularly susceptible to these forces.
Image ArtifactsÂ
- Metallic dental materials can cause distortions in MRI images, known as artifacts.
- Artifacts result from magnetic field inhomogeneities introduced by the metal and can obscure or mimic pathology, complicating diagnosis.
- The extent of artifact formation depends on:
- The material’s composition
- Its size and shape
- Its location relative to the imaging area
Thermal Effects
- Radiofrequency energy used during MRI can induce heating in metallic objects.
- While most dental materials do not heat to dangerous levels, larger metallic restorations or appliances pose a potential thermal injury risk.
- Proper assessment and monitoring of metal presence are essential.
Types of Dental Materials & Their MRI Compatibility
Ferromagnetic vs. Non-Ferromagnetic Materials
- Ferromagnetic materials strongly interact with MRI’s magnetic field and may cause movement, heating, or artifacts.
- Non-ferromagnetic materials are MRI-safe and do not cause significant interference.
Common Dental Materials & Their Ferromagnetism
| Dental Material | Ferromagnetic? | Potential MRI Issues |
| Stainless Steel (410, 430, 440 series) | Yes | Can cause artifacts, possible displacement |
| Nickel-Chromium (Ni-Cr) alloys
 |
Mildly | Minor artifacts |
| Cobalt-Chromium (Co-Cr) alloys
 |
Mildly | Minor artifacts |
| Titanium & Titanium Alloys
 |
No | Safe for MRI |
| Zirconia (Ceramic)
 |
No | Safe for MRI |
| Gold, Silver, Platinum
 |
No | Safe for MRI |
| Dental Amalgam (Silver Fillings)
 |
No | Safe for MRI |
MRI & Dental Materials: Risks & Artifacts
What Happens If You Have Ferromagnetic Braces During MRI?
- Braces may move slightly due to magnetic forces.
- Strong artifacts may distort brain and head scans.
- Heating effects are rare but possible.
- In extreme cases, braces could cause minor injury or discomfort.
MRI of Abdomen, Chest, or Legs: Does It Affect Dental Materials?
- No significant impact as the magnetic field is concentrated in the core.
- Teeth are peripheral tissues, where the field is weaker.
- No risk of displacement for dental materials.
- However, image artifacts may still occur in head scans.
How Image Artifacts Happen (Scientifically)?
- Metals disrupt the uniformity of the MRI magnetic field.
- This leads to signal voids, image distortion, or warping.
- Severe artifacts may require a repeat scan, leading to wasted time and cost.
Precautions for Patients with Dental Work Undergoing MRI
For MRI of the Head & Neck:
- Braces & Stainless-Steel Restorations: May cause significant artifacts—removal might be recommended.
- Titanium, Zirconia, or Ceramic Crowns & Implants: Safe with minimal artifacts.
- Dentists & Radiologists Should Communicate to decide whether braces should be removed.
For MRI of the Abdomen, Chest, or Limbs:
- No removal needed as the mouth is outside the main MRI field.
- Weak magnetic fields near the mouth pose no significant risk.
How to Check If a Dental Material is Ferromagnetic?
- Use a simple magnet: If it attracts, it’s ferromagnetic.
- Refer to dental records: Material composition should be listed.
Can a Non-Ferromagnetic Splint Be Used to Cover Dental Materials?
- Materials like polycarbonate, silicone, acrylic resin, or titanium can act as splints.
- Used only in rare cases where movement risk is high.
- Not commonly used as most dental materials do not move significantly in MRI.
MRI Magnetic Force & Potential Injuries
- MRI magnets produce force in the range of 1.5T to 7T (~1.5 million Pascals for clinical MRIs).
- This force is not strong enough to remove braces or extract a tooth.
- However, it can pull loose ferromagnetic objects, leading to injury.
Force Required to Dislodge Braces in Lab Studies
- Lab tests show that braces require significant force (~300–500 N) for removal.
- MRI-induced forces are much lower than this threshold, making displacement highly unlikely.
Alternative Options for MRI Patients with Dental Work
- CT Scan or Cone-Beam CT (CBCT) for specific head/neck conditions.
- Ultrasound for soft tissue imaging where applicable.
- Special MRI sequences to reduce metal artifacts (e.g., MARS, SEMAC, VAT).
Q & A: Common Patient Concerns
Q: My doctor recommended an MRI, but I have braces. What should I do?
A: Consult your orthodontist and radiologist; braces may cause artifacts in head scans.
Q: Will an MRI of my abdomen affect my dental fillings?
A: No, dental fillings are non-ferromagnetic and will not be affected.
Q: Can MRI rip out my dental implant?
A: No, titanium implants are MRI-safe and will not move.
Conclusion: Key Takeaways
✔ Most modern dental materials (e.g., ceramics, zirconia, lithium disilicate, composite restorations) and even outdated materials (e.g., gold, dental amalgam) are MRI-safe.
✔ Ferromagnetic materials (stainless steel braces, some crowns) may cause artifacts but rarely pose safety risks.
✔ MRI of the abdomen, chest, or limbs does not affect dental materials significantly.
✔ MRI of the head & neck may require orthodontic consultation if braces are involved.
✔ Precautions & alternative imaging techniques can be used if needed.