It is generally safe to have an MRI with metal crowns. MRI scanners use powerful magnetic fields and radio waves to create images of the inside of the body, and they do not produce any harmful radiation. However, metal crowns can sometimes cause problems during an MRI because they may contain metal that can be affected by the magnetic field. This can cause the crown to move or distort the image, or it may produce a ringing noise during the scan. To minimize these effects, it is recommended to inform the MRI technician about any metal crowns that you have before the scan. The technician can then take steps to ensure that the crown does not interfere with the scan.