Silver amalgam filling: The advantage is that it is cheap and wear-resistant. The disadvantage is that due to its metallic color, it cannot be used for anterior teeth; due to the shrinkage of silver amalgam, there is no adhesion between the amalgam and the teeth, the edges of the fillings are not tight, forming micro-leakage, and long-term use may occur again at the junction of the silver amalgam and the teeth. This restoration method has been gradually phased out in developed countries. Light-cured resin filling: The advantage is that it is close to the color of the tooth and can be used for both front and back teeth. The disadvantage is that it can only be used for smaller fillings of wormy teeth because of the shrinkage during the light hardening process. If the cavity of a worm tooth is very large or involves the adjacent surface of the tooth, resin fillings are not so suitable in the long run. It tends to break and fracture, leading to the recurrence of worm teeth or blocked teeth, etc. Some living pulp teeth may also develop post-operative sensitivity due to the irritation of the resin and bonding agent. Currently used in developed countries mainly for minor defects in anterior teeth. Inlay restoration: This method is currently used in most developed countries for the restoration of posterior tooth defects. For example, very large defects of wormy teeth, silver mercury and resin are not ideal. A more ideal restoration method is to restore the chipped tooth with an inlay. It can restore the shape and function of the tooth very well. Especially for cavities damaged by worm teeth to the adjacent surface of the teeth, the long-lasting effect is better. Because the inlay is made outside the body, the produced inlay adjacent surface is smooth and not easy to attach biofilm and food residue, which reduces the possibility of secondary caries. Especially for the large area of destruction of the tooth body can be restored by high inlay without crown restoration, avoiding the stimulation of the crown edge to the gum and protecting the health of periodontal tissue. Inlays can be classified according to material as metal alloy inlays, resin inlays, porcelain inlays, etc. Indications for inlays: various severe dental defects involving cusps, incisors, marginal crests, and symphyseal surfaces, requiring occlusal reconstruction and cannot be restored with general materials; poor adjacency of dental defects or serious food embedding, requiring restoration of adjacent contact points; fixed bridges with cavities in the abutment teeth or to place plugs, plugs and slot attachments.