If the periodontitis tooth is very loose, whether it should be extracted or not should be analyzed on a case-by-case basis: a. To combine with the clinical examination, if it is a single tooth loosening need to determine whether it is a vertical bone destruction due to occlusal trauma causing localized single tooth loosening, to combine with the clinical analysis and consultation to perceive whether there is trauma to the tooth. Second, the entire periodontal bone destruction is seen by taking X-rays, while for the destruction of a single tooth. If it is clear that there is no serious horizontal bone resorption due to occlusal trauma of a single tooth, this kind of tooth can be loosened very much, but it is possible to reduce its (dental) force by adjusting the occlusion and let it recover slowly, and finally the looseness can be improved significantly. If horizontal bone resorption causes significant loosening of the tooth, and the surrounding teeth or other symmetrical teeth in the same position have different degrees of loosening, it may often need to be extracted in combination with the clinical film.