Dental cavity is equal to dental caries, which is a chronic progressive destructive disease of the hard tissues of the teeth. It causes the destruction of hard tissues of teeth, resulting in the formation of cavities. The caries or cavity is an irreversible lesion and should be filled in time at the early stage to stop its further development. How to fill the cavity needs to be treated by dental filling in the endodontics department of the specialized dental hospital or the dentistry department of the general hospital. Filling is to restore the anatomical appearance and physiological function of the tooth by removing the diseased, decayed, blackened and softened tooth tissue with bacterial infection with special dental instruments, cleaning it up and filling the cavity with special dental filling materials. Filling treatment is the most widely used and better caries treatment method at present, the purpose is to terminate the process of caries lesion, protect the dental nerve, protect the remaining dental tissues, and restore the inherent form and physiological function of the teeth. Generally, it is mainly divided into two steps, removing the decayed tooth tissue and the weak tooth tissue which lost its support, and preparing the cavity into a certain reasonable form according to the performance of the filling material. The filling material will be filled in the cavity to restore its inherent form and function.