There are two main aspects of preserving the roots of teeth. The first is the destruction of only a few teeth or individual teeth, the roots are preserved through treatment, and then the crowns are restored with pile crowns, retaining pins and various crowns and porcelain crowns to restore the integrity of the dentition and to better restore function, pronunciation and aesthetics. Secondly, all the teeth are damaged and only some roots remain, or only individual teeth with elongation, loosening and resorption of the alveoli remain. In this case, partial roots or loose teeth can be selected for treatment, and the roots can be preserved. On the basis of this, an overdenture can be made to achieve better restorative results. However, the retention of the roots is conditional. Generally speaking, if the periodontium is in good condition, the gingival pockets are not inflamed, there is no periodontal pus overflow, and the roots have some bone support, the roots can be preserved by treatment. Since the roots connected to the tooth socket through the periodontium are preserved, it can reduce the resorptive atrophy of the tooth socket caused by tooth extraction, ensure the stability and support of the denture, and improve its chewing performance. The retained roots can also maintain part of the physiological perception of normal chewing pressure, reduce the sinking of the denture, protect the alveolar ridge, and contribute to health. However, for teeth with serious root destruction. However, for teeth or roots with serious root destruction and root resorption, or even alveolar resorption reaching the apical part of the root, or teeth or roots with severe loosening, there is really no retention value, and they should be extracted early to avoid causing other oral diseases.