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If you’ve ever had an MRI, you know that they ask you to remove all metal objects before the exams. Rings and earrings are easy. But is it possible to do MRI with dental implants? After all, they cannot be removed for the duration of the procedure.
Why before MRI remove things made of metals
The principle of operation of the magnetic resonance tomograph is to create its own magnetic field, in which the patient is located. Hydrogen atoms in the patient’s body resonate with the magnetic field and the result is recorded as a series of images. These are virtual slices of organs and tissues that help to make an accurate diagnosis.
Doctors are asked to leave metal objects out of the room with the CT scanner so that no metal or alloy that can magnetize accidentally enters the magnetic field. All substances are divided into:
- Diamagnetics. Their magnetic susceptibility is negative. Silicon, gold, silver are diamagnetics.
- Paramagnetics. Able to be magnetized, but their magnetic susceptibility is very weak, it is difficult to fix, so only scientists understand the difference between dia- and paramagnetics. Platinum, aluminum are paramagnets.
- Ferromagnetics. Magnetic susceptibility of such metals is high, they are able to magnetize and change location under the influence of a magnetic field. Iron, cobalt, nickel are ferromagnets.
Based on these properties, doctors are asked to remove metal objects during magnetic tomography. Ferromagnetics not only distort images, heat up in the magnetic field, but can shift under its influence.
Is it possible to do MRI with titanium implants
Titanium is a paramagnetic. Theoretically, it is magnetizable. In practice, its magnetic susceptibility is 10 to 5. These values are so small that we commonly say that titanium is not magnetized. It interacts with the magnetic field within limits that do not affect the results of the examination. MRIs with dental implants can be done on all organs, including MRIs of the brain. Fears that the implants will shift are unfounded, for the simple reason that titanium is not ferromagnetic. It does not heat up or change location under the influence of a magnet. Implants are not a contraindication for tomography.
What about crowns and posts
The question arises: what about the crowns that are placed on the implant? Some of them contain metals.
Modern metal dental crowns are created from alloys with weak or negative magnetic susceptibility. However, crowns that are many years old can distort the picture and negate the diagnosis. Moreover, the more crowns, the greater the distortion.
Do MRI with metal crowns in principle can be done, provided that the patient warns the doctor about their presence. The doctor will take into account all factors: the examination body, the alloy of the prosthesis, and will decide whether to conduct or refuse the procedure.
MRI with a pin in the tooth (stump inlays) has no contraindications if the pin is made of fiberglass. MRI with a metal post in the tooth is carried out, because the amount of metal there is minimal and on the results practically does not affect the results.
The doctor should be warned about metal crowns and posts. Ideally, he should be told what type of alloy was used. This can be found out at the dentist’s office where the denture was placed. New CT scanners take such information into account and correct the data.
Conclusions
- There is no reason not to do an MRI if there are implants. Dental titanium is virtually unmagnetizable. Titanium implants do not affect the results of the examination.
- Metal posts are also not a contraindication to tomography. The amount of metal there is minimal, and in fiberglass products there is no metal at all.
- Metal dental crowns can distort the results. This depends on the metal they are made of, the amount of dentures and the organ being examined. Modern denture materials have low magnetic susceptibility. They are safer. In general, it is better to choose metal-free designs when placing crowns. This will prevent problems with MRI in the future.