Tooth fracture after filling is divided into the following two cases: 1, live pulp teeth: decayed teeth, tooth fracture after tooth filling, if the area of tooth decay is large, the tooth tissue that needs to be removed is more, which destroys the resistance shape of the tooth, such teeth are more likely to fracture when they are subjected to larger external forces; 2, after filling teeth with root canal treatment, doctors generally recommend early crown restoration, otherwise it is also easy to Bite fracture. Because after root canal treatment, the tooth lacks the supply of nutrients, the tooth tissue will lose its elasticity, such as a dry tree, which becomes fragile and easy to fracture when it loses the supply of nutrients. In contrast, the trunk of a living sapling tree will have stronger resistance, more elastic and less prone to fracture, so this kind of tooth is easy to fold and crack after filling alone, and patients are recommended to have crown restoration.