Scaling clinically called cleaning, generally still recommended to remove tartar, plaque after polishing. 1. Whether it is a hand instrument cleaning or ultrasonic cleaning, the operating instrument will leave small scratches on the surface of the teeth, making the surface of the teeth rougher and not smooth enough, easy to form plaque, pigmentation on the surface of the teeth redeposited. 2. Some teeth and root surface of the plaque, pigment, and the combination of the surface of the tooth is more tight, through ultrasonic oscillation or cleaning tartar easy to fall off, while the plaque, pigment is relatively difficult to remove, the work efficiency is low. The polishing technique can remove the residual plaque and pigment on the tooth surface, make the tooth surface clean, and reduce the re-adhesion speed and degree of plaque. Therefore, polishing is an essential step after scaling and belongs to the content of scaling technique.