Many people have heard that when doing an MRI, you cannot have any metal objects on your body, otherwise it will affect the results of the examination or even endanger the safety of the person. It is possible to remove movable dentures in the mouth, but what should be done if the mouth is equipped with fixed metallic dental implants? The basic principle of MRI: the human body contains very rich water, different tissues, the content of water varies, if you can detect the distribution of this water information, you can draw a more complete picture of the internal structure of the human body. The basic principle of MRI is to place the human body in a special magnetic field and use radio frequency pulses to excite the hydrogen nuclei in the water molecules in the human body, causing the hydrogen nuclei to resonate and absorb energy. After stopping the radio frequency pulse, the hydrogen nuclei emit radio signals at specific frequencies and release the absorbed energy, which is collected by the receiver outside the body and processed by an electronic computer to obtain images, which is called MRI. Since there is a very strong magnetic field in the MRI machine and the MRI examination room, it is absolutely forbidden to perform MRI examination for those who are equipped with pacemakers, those who have metal clips or metal stents after vascular surgery, or those who have undergone metal stent surgery for coronary arteries, esophagus, prostate, or bile duct, otherwise, the metal will be attracted by the strong magnetic field and move, which may have serious consequences. The material used for artificial implants is pure titanium, which is the best known biocompatible metal, and is a non-magnetic metal that will not be magnetized in a large magnetic field, so the implant itself does not have any effect on the MRI. The implant is a non-magnetic metal and will not be magnetized. All-porcelain materials are non-metallic and have no effect on MRI, while metal porcelain teeth have different degrees of interference with MRI imaging due to different types of metals. In detail, the porcelain metal commonly used for oral restoration are gold alloy, nickel-chromium alloy, cobalt-chromium alloy, etc.. A large number of experimental data show that gold alloy precious metals have only slight artifact interference in MRI, while non-precious metals such as nickel-chromium alloy and cobalt-chromium alloy produce larger artifacts, which have a certain impact on the MRI examination. Therefore, we recommend the use of all-ceramic restorations.