(A) re-located in the neck of the anterior teeth in order to avoid postoperative exposure of the tooth root, should try to retain the gingiva, the incision from the gingival margin of the root side of the 0.5 ~ Imm at the incision, or from the gingival margin of the internal oblique incision, excision of pockets in the wall of the epithelium, the gingival flap re-located in the cervical part of the teeth in the restoration of the commonly used modified Widman flap surgery. Modified Widman flap surgery is suitable for moderate or deep periodontal pockets in anterior and posterior teeth, which do not require bone shaping. Characterized by the complete removal of the pocket wall epithelium and inflammatory tissues; flap only up to the top of the alveolar ridge, without bone repair, gingival flap reset should try to cover the adjacent bone, not to expose the bone. These measures are to reduce bone resorption, increase the opportunity for new attachment; at the end of the surgery, healthy gingival connective tissue can be closely adhered to the tooth surface, favorable healing, and less gingival recession. (ii) reset is located at the top of the alveolar ridge in the posterior region In order to try to eliminate the periodontal pockets, in the keratinized gingiva has a sufficient width of the site, you can be close to the bottom of the pockets and the top of the alveolar ridge for the inward slanting incision of the Vl, resection of a portion of the pockets wall of the gingiva, reduce the height of the gingival flap and thinning gingival flap, gingival flap reset is located in the alveolar ridge at the top of the root surface, just be able to the top of the ridge of the bone covered with a shallow, but the roots of the teeth are more exposed. Surgery with such characteristics is called crest-top in situ restoration flap, suitable for posterior teeth to eliminate medium depth and deep periodontal pockets, as well as those who need to repair bone defects, but also for those who need to expose the root bifurcation due to root bifurcation lesions, but all must have a sufficient width of keratinized gingiva, in order to avoid surgical resection of pockets wall gingiva will be keratinized gingiva all the way to the removal. (C) Rootward reset When the bottom of the deep periodontal pocket exceeds the membranogingival union, and the keratinized gingiva is narrower, it can be made from the gingival margin of the internal oblique incision and bilateral vertical incision Vl, turn up the full-thickness flap, scraping, cleaning, and then the gingival flap to the root side of the push, reset at the level of the top of the alveolar ridge just covered, and be sutured and fixed. The advantage is that both the elimination of periodontal pockets, so that the lesion area (such as the root bifurcation area) is fully exposed, easy to self-cleaning, while preserving the keratinized gingiva, known as the rootward reset flap. Root-to-replacement flap is suitable for those whose periodontal pocket base exceeds the membrane-gingival joint boundary, and those whose keratinized gingiva is too narrow due to root bifurcation lesions that require exposure of the root bifurcation. The characteristics of the internal oblique incision from the gingival margin of not more than lmm, as far as possible to preserve the gingival tissue; must be made longitudinal incision, and more than the membrane gingival union to the migration groove, in order to facilitate the flap to the root reset; gingival flap reset to just cover the top of the alveolar ridge; the use of suspension suture, the flap suspension to the desired position, and the use of plugging agent to assist in the fixation of position, preventing the gingival flap to the coronal displacement. In addition, in order to widen the attached gingiva, rootward repositioning of the half-thickness flap can be performed, leaving the periosteum and part of the connective tissue on the bony surface and repositioning the half-thickness flap on the root side of the alveolar ridge. The epithelium crawls towards the crown and covers the exposed connective tissue during the healing process of the traumatic el, which widens the attached gingiva and prevents resorption of the alveolar ridge.