The function of wearing braces on teeth is as follows: 1, the crown of living pulp tooth has a large area of caries, and only a small amount of healthy dentin remains after removing the decayed dentin tissue, which is not enough to fix, especially the filling material is easy to fracture when bearing large biting force, and by making a full crown can enhance the resistance of teeth, and can restore the anatomical form of teeth and improve the chewing efficiency; 2, the tooth after root canal treatment has lost the nutrition of pulp After root canal treatment, the tooth loses the nutrient supply from the pulp, and the tooth becomes brittle gradually, and the color is different from the neighboring teeth. Full crown restoration can avoid fracture or rupture of dead pulp teeth, and can change the color of the tooth to improve the aesthetics.