Gingival staining refers to gingival discoloration caused by metal oxides on the gingival margins of metal porcelain restorations. Light and heavy differently affect the aesthetic effect of the restoration, non-precious metal common complications, very difficult to deal with. Porcelain restoration cervical margin black line (gingival staining) problem, clinical investigation 355 people 1052 units of porcelain restorations, the incidence of cervical margin black line in 1995 was 15.0%, about 1.0% in 2000. Gingival stain causes: 1, tissue inflammation oxide diffusion; 2, porcelain gingival margin oxide; 3, metal base crown generation oxide (crevice corrosion, biological corrosion), gingival margin gap, poor abutment preparation, poor adhesion, metal crystalline structure problems; 4, gold porcelain together with the design of the part. Countermeasures 1, porcelain cover metal edge, crown edge design to the gingival sulcus 1/2, all-ceramic cervical edge porcelain edge technology. 2, material selection series of materials, alloy, embedding material, bonding materials. 3, tooth preparation, shrinkage technology application of gold porcelain restoration crown edge shoulder, 135 degrees concave shoulder, table smooth, uniform, polishing treatment, neck shoulder thickness 0.35mm + 0.5mm porcelain layer, crown edge stop in the gingival sulcus. 4, model processing, gap coating 0.1mm, properly prepared generation type. 5, the processing of the base crown, sandblasting treatment before bonding, rubber cone polishing metal crown edge. 6, bonding, reduce the amount of crown edge floating, bonding material overflow ditch, reconciliation ratio, bonding timing, pressurized bonding, the right way to manage excess bonding material. 7.Prevent gingivitis, avoid gingival damage, avoid gingival irritation, preventive medicine, 10% iodine compound, oral health care after restoration. Important factors to stop gingival staining: formal tooth preparation, preparation of colorimetric, information transfer between medical technology, the use of precious metals, porcelain edge technology, prevention of gingival damage, the use of bonding agents and other technical aspects, the aesthetic effect of pure porcelain edge from the crown edge of staining, integrity and secondary caries better, advocate the use of porcelain edge instead of conventional metal edge. Electron microscopic observation of metal, porcelain surface after different treatment morphology, prove that the metal surface sandblasting, porcelain surface with 32% phosphoric acid etching 1mm effect is better.