The retention part of a double crown denture consists of two layers of crowns, the inner crown is bonded to the tooth and the outer crown is connected to the denture by special components. There is friction between the two layers of crowns, so that the denture can be fixed effectively. The advantages of precision denture: 1.No exposure of retainer, beautiful appearance; 2.Use own teeth as much as possible, reduce extraction; 3.Protect abutment teeth, reduce caries, periodontal disease; 4.Good retention, natural and comfortable; 5.Easy repair, long service life. The indications for precision denture: those with few remaining teeth; those with poor remaining teeth; those with high aesthetic expectations, etc.