The following three principles need to be followed for restoration of dental defects. First, the biological principle. Biological principle refers to the tooth defect repair, the restoration body needs to have no adverse stimulation to the dental tissue, that is, the restoration body needs to have good biocompatibility with the surrounding dental tissue, oral tissues, no adverse stimulation, that is, follow the biological principle. Second, the restoration of dental defects needs to follow the principle of mechanics. This is because dental defects are generally restored with crowns, inlays, or pile crown restoration, all need to follow the principles of mechanics, to have sufficient retention and stability. Third, the principle of aesthetics. Restoration of dental defects, especially anterior restorations, need to follow the aesthetic principles. The restored tooth tissue needs to be closer to the adjacent teeth and more aesthetically pleasing. In terms of color, morphology and arrangement, it is closer to the neighboring teeth to achieve the purpose of falseness.