A large number of metal porcelain teeth will have some effect on the results of the MRI of the head, and must be removed if the nasopharyngeal MRI is done and particularly precise imaging information is needed. A small number of metal porcelain teeth will have little effect on the results of the MRI, only when doing the MRI there is a large magnetic field, to take off all the metal on the body, so as not to absorb into the machine. Do not do the head examination, metal porcelain do not need to take. Just keep your mouth closed when you do the MRI. Since there is a very strong magnetic field in the MRI machine and the MRI examination room, it is strictly forbidden for people with pacemakers, metal clips or metal stents after vascular surgery or other metal stent surgery on the coronary arteries, esophagus, prostate, or bile ducts to have an MRI examination, otherwise, the metal will be attracted by the strong magnetic field and move, which may have serious consequences and lead to Otherwise, the metal will be attracted by the strong magnetic field and move, which may have serious consequences and life threatening. Generally, outside the MRI room of a hospital, there are red or yellow signs indicating that MRI is strictly forbidden. If there are other metallic foreign objects in the body that cannot be removed, such as metal internal fixations, artificial joints, metal dentures, stents, silver clips, shrapnel, etc., they are relatively contraindicated and should be closely observed to prevent the metal from moving in the strong magnetic field and damaging the adjacent large blood vessels and important tissues, which may have serious consequences. Those who have metal contraceptive rings and movable metal dentures must be removed before the examination.