The pathological changes of periodontitis include destruction of alveolar bone, mostly resorption of the alveolar bone ridge, but also some areas with compensatory abnormal bone proliferation, which leads to changes in the shape of the alveolar bone and loss of its original physiological shape, such as blunting and thickening of the edges of the alveolar bone in the form of a platform, uneven height, vertical resorption to form sub-bony pockets, and pit-like resorption between teeth. The morphology of the bone is directly related to the morphology of the gums. Due to the deformity of the bone, the gums often lose their normal physiological shape and increase the accumulation of plaque. Therefore, to restore the normal physiological shape of periodontal soft and hard tissues, bone lesions and deformities must be corrected simultaneously during flap surgery to create the conditions for a good gingival shape. Liang Zhaozhong, Department of Special Oral Surgery, Urumqi Stomatological Hospital Excisional bone surgery (resectiveosseoussurgery) is the surgical repair of the alveolar bone in the diseased area to restore the normal form and physiological function, including osteoplasty and osteotomy. Both osteoplasty and osteotomy aim to repair the marginal part of the alveolar bone to restore or approach the normal shape, while osteoplasty emphasizes the revision of the bone shape without removing the supporting bone, while osteotomy removes a portion of the supporting alveolar bone. In clinical practice, these two methods often need to be used together and are difficult to distinguish strictly. The advantage of this type of surgery is that it can effectively eliminate periodontal pockets and improve the appearance of the gums; the disadvantage is that the bone is sacrificed. I. Indications 1. The normal bone profile should be thin at the top of the crest, in a displaced state, with a longitudinal depression on the bone surface of the tooth root question. If the crest of the alveolar bone is rounded and fat or protrudes in the shape of a ledge, it needs to be trimmed and shaped. 2, the normal shape should be higher bone ridge of the adjacent question, and lower bone ridge of the buccolingual surface, and the top height of the bone ridge of adjacent teeth is more consistent. If the bone edge line is uneven or the adjacent bone is lower than the buccal and lingual surfaces and the bone edge line is anti-wavy, it needs to be trimmed and shaped, and if necessary, a small amount of supporting bone can be removed. 3, shallow one-wall bone pocket or wide and shallow two-wall bone pocket is difficult to have new bone repair. The morphology of the bone defect determines the surgical method to be used. Three-wall bone pockets, especially narrow and deep ones, can be successfully treated with new attachment and bone regeneration methods, and should be treated with regenerative methods as much as possible; one-wall bone pockets and wide and shallow two-wall bone pockets are difficult for the implanted bone or bone replacement material to fix, survive and form new attachment healing, so osteoplasty is usually needed to trim the shape of the alveolar bone to eliminate the bone pockets. 4.Pit-like resorption of adjacent bone, with less possibility of bone regeneration, the thinner and lower side of the bone wall can be removed to form a slope, or both buccal and lingual walls can be removed to eliminate the pit-like shape. 5, to the adjacent missing teeth area tilted teeth, often in the missing side of the formation of narrow and deep sub-bone pockets, bone repair into a gradual shift osteoplasty and osteotomy: (1) removal of shallow one-wall bone pockets or wide and shallow two-wall bone pockets (2) adjacent pit-like bone defect repair (3) bone crest top hypertrophy in the shape of a ledge repair (4) tilted teeth deep sub-bone pockets (5) uneven bone margins, often need to make bone resection of the long bevel in order to eliminate periodontal pockets. 6, root bifurcation lesion for Ⅱ degree but the attached gingival width is narrower, or root bifurcation lesion for Ⅲ degree, regenerative treatment is difficult to succeed, need to make root to reset flap to expose the bifurcation area, and need to trim the root question bone edge of split XIX, forming a thin and inter-root longitudinal concave shape, gingival attachment can form a good shape, thus facilitating plaque control and maintenance of good oral hygiene. Second, the surgical method 1, flip the periosteal flap according to the requirements of gingival flap reset to decide the location of the internal oblique incision, such as root to reset flap, in situ reset flap, etc. Routinely flap and scrape away plaque, tartar and granulation tissue from the root surface to fully expose the shape of the bone. 2. Gently and intermittently grind away the hypertrophic and uneven bone margins or a wall of bone pockets into a displaced slope shape with a #8 round drill on a turbine handpiece. Cooling water must be available during the debridement process to avoid causing osteonecrosis. Damage to the tooth should also be avoided. The bone surface between the teeth and the roots should form a physiological longitudinal groove, and the bone edge can also be trimmed with a bone chisel. 3, The gingival flap should completely cover the bone surface when resetting to reduce the resorption of the alveolar bone. 4, The rest of the steps are the same as flap surgery.