Veneers are made by grinding the teeth. When veneers are made, not only the exogenous pigment, soft food scale and plaque adhering to the tooth surface are removed, but also the labial discolored tooth tissue is ground away to expose the fresh enamel layer, which helps to enhance the bonding effect of resin cementum. Since the veneer has a certain thickness, if the veneer is directly bonded without grinding the teeth, it will make the lip side of the tooth protrude too much and form discomfort. Some teeth are pitted on the surface, creating a substantial defect, which can be eliminated with a dental preparation to eliminate the inverted concavity. Dental preparation can also prepare adjacent grooves on the proximal and distal mesial surfaces of the crown to enhance retention and prevent veneer loosening or loss.