Full metal crowns are prepared by professionals, including maxillofacial preparation, axillofacial preparation, adjacent surface preparation and finishing. 1. Maxillofacial Preparation: Using a lathe needle to prepare several indicative grooves on the maxillofacial side of the tooth at a depth of about one millimeter, and then using a short cylindrical lathe needle to uniformly grind the desired thickness of the maxillofacial side along the indicative grooves. 2. Axial surface preparation: Use the lathe needle to set deep grooves in the buccolingual proximal-medial, medial-medial, and distal-medial axial corners, and then grind a circle of dental tissue evenly. Enough space is prepared for the subsequent restoration. 3. Adjacent surface preparation: Using a long, thin lathe needle to open the proximal- and distal-medial adjacent surface contact points, remove the inverted concavity, and converge 2 to 5 degrees to the maxillary surface. 4. Finishing: Prepare all sides of the tooth using a polishing needle to make the edges smooth and rounded, ensuring a one-millimeter thick restoration gap on the jaw. Metal full crown tooth preparation needs to go to the regular dental hospital by the dentist to operate.