Teeth are composed of four layers of tissue, divided into three layers of hard tissue and one layer of soft tissue. The outermost layer of the tooth is the enamel, which is the white hard tissue that constitutes the surface of the tooth and is the hardest and most highly calcified tissue in the tooth, mainly composed of calcium phosphate and calcium carbonate; the dentin is the hard tissue that constitutes the surface of the tooth root and is yellow in color; the dentin is located in the inner layer of the enamel and the dentin and constitutes the main mass of the tooth, which is not as hard as the enamel and is rich in dentin tubules and has a pulp cavity at the innermost part. The pulp, commonly known as the dental nerve, is a cellular tissue filled with pulp cavities, which is rich in blood vessels, nerves and lymph. The hard tissues of teeth are in the oral environment, facing the erosion of acid produced by bacteria, and also the repair of mineral ions in saliva, always following the law of mineralization – demineralization – remineralization – remineralization, when the tooth is cracked by external forces, the hard tissues of teeth, including enamel or dentin, basically have no ability to heal themselves. If the crack is small and shallow (i.e. enamel crack), just use desensitizer or fluoride to promote enamel remineralization; if the crack is large and deep (i.e. dentin crack) and there is no inflammation, you can directly retain the living pulp and do crown restoration; if the crack is large and deep (i.e. dentin crack) and there is inflammation, you can If the tooth is completely cracked (i.e., pulpal floor crack) and the tooth has lost its therapeutic value, the affected tooth should be extracted and then restored with a crown and bridge. Therefore, regardless of the symptoms of cracked teeth, patients should seek timely medical attention and be given the best treatment plan by the doctor to avoid missing the best treatment time.