Periodontal tissue regeneration (regeneration) is the elimination of periodontal pockets and the formation of neo-adhesive healing, i.e. the lost periodontal tissue due to periodontitis is rebuilt, with new bone and alveolar bone formation, with new periodontal fibers connecting them, and the newly formed bonded epithelium located on the coronal side of the base of the periodontal pocket before treatment. This is the ideal result of periodontal treatment. Surgical treatment methods aimed at obtaining periodontal tissue regeneration are called regenerativesurgery and mainly include bone grafting and guided tissue regeneration, or they can be combined with both or with some other methods to promote regeneration such as biological treatment of the root surface and the use of growth factors. I. Periodontal bone grafting (bonegrafts) is a method of repairing alveolar bone defects caused by periodontitis using graft materials such as bone or bone substitutes. It is a regenerative periodontal surgery, aiming to promote new bone formation, repair bone defects and restore the anatomical shape of alveolar bone through grafting materials to achieve ideal bone regeneration or newly attached healing. It is suitable for two-walled and three-walled bone subpockets, or II degree root bifurcation lesions, where the gingival flap can cover the bone surface and root bifurcation area. (I) Materials for bone grafting The performance of materials for bone grafting mainly depends on whether the materials have osteogenic (or osteogenic) ability, osteoinductive ability and bone guidance ability. Osteogenesis means that the cells contained in the bone grafting material can form new bone; osteoinduction is a chemical process in which molecules in the bone grafting material (e.g. bone forming proteins, BMPs) can convert neighboring cells into osteoblasts to form new bone; bone guidance is a physical effect in which the matrix of the bone grafting material forms a scaffold to facilitate the entry of cells from neighboring tissues into the bone grafting material to form new bone. The selection of bone material should also consider the biocompatibility of the material, clinical operability, less surgical damage, less postoperative complications, predictability of postoperative results, and patient acceptance. The following four types of materials are currently used for bone grafting: 1. Autologous bone grafting materials are taken from the patients themselves. It can be taken from the bone of the extraction wound, maxillary tuberosity, alveolar ridge of edentulous area, posterior molar area and chin in the oral cavity, or bone fragments obtained during osteoplasty and osteotomy. It is also possible to take bone from the iliac bone, but it is no longer used because it is more painful to take bone from the iliac bone and it tends to cause resorption of the tooth root at the implantation site. Studies have shown that autologous bone has osteogenic capacity and that autologous bone grafting for periodontal bone defects can result in new connective tissue attachment, but the results are not easily predictable. The disadvantage is that autologous bone extraction increases the surgical trauma in the donor area of the patient. 2. Allogeneic bone is derived from different individuals of the same species. There are fresh frozen bone and bone marrow from healthy donors, freeze-driedbonea11ograft (FDBA), and decalcified freeze-drieda11ograft (DFDBA). However, the donor of allogeneic bone must undergo a rigorous health screening and the allogeneic bone must also be treated by freezing, radiation or chemical methods to eliminate its antigenicity and the risk of disease transmission due to possible infections such as viruses. The advantages of allogeneic bone are the abundance of bone sources, simplification of the operation, and elimination of trauma and pain caused by the patient’s bone extraction. The disadvantage is that the risk of antigenicity and disease transmission still cannot be completely excluded. Some studies have shown that freeze-dried bone has a bone-guiding effect, while decalcified freeze-dried bone exposes the bone-forming proteins in the bone matrix after decalcification treatment, and thus has an osteoinductive effect, and the clinical bone regeneration effect is better than that of freeze-dried bone. 3. Allogeneic bone is derived from different species. In recent years, there is a special treatment of calf bone, leaving only the inorganic component of bone scaffold structure for natural, multi-solitary inorganic bone matrix, such as Bi0-Oss, and studies have shown that there is new bone formation within the multi-solitary structure after clinical application. 4, bone substitutes are non-bone graft materials. There are calcium phosphate biological materials such as hydroxyapatite (hydroxyapatite, HA), fj a tricalcium phosphate (p-tricalciumphosphate, p-TCP), materials of coral origin such as natural coral materials, porous hydroxyapatite made of coral materials, other materials such as calcium sulfate paste ( plasterofcalciumsulfate), bioactiveglass (bioactiveglass), cartilage, sclera, etc. Calcium phosphate biomaterials have been used clinically since the mid-1970s until now and have good biocompatibility without causing any inflammatory reactions or rejection; these materials are bone-guided but not osteoinductive. Hydroxyapatite HA has a calcium to phosphorus ratio of 1.67, similar to bone, and HA is generally not resorbable. j3-tricalcium phosphate has a calcium to phosphorus ratio of l.5, and TCP can be partially resorbed. Coral-derived materials are biocompatible and have been used in periodontal clinics. Natural coral materials are absorbed slowly, taking several months, while porous hydroxyapatite is not absorbed or is absorbed only after several years. Paste calcium sulfate is completely absorbed 1 to 2 weeks after implantation, and an animal study showed that significant bone and dental bone regeneration was obtained when it was implanted in triple-walled bone pockets. Bioactive glass is composed of sodium salt, calcium salt, phosphate and silica, and is applied in V1 cavity department as irregular particles of bioglass with particle size of 90-1709m or 300-350um in diameter. after contact with tissue fluid in the implant, the surface of the particles undergoes chemical changes and attracts osteoblasts, resulting in the formation of new bone. (B) Method of periodontal bone grafting 1. Routine disinfection and anesthesia (bone recipient area and bone donor area). 2.The incision of the bone-receiving area should be designed to ensure that the mucoperiosteal flap can completely cover the bone-receiving area. In order to preserve more gingival flap tissue, the position of the internal oblique incision should be as close to the gingival margin as possible, and some people even believe that the internal oblique incision is not needed but the sulcular incision is used. In order to preserve the adjacent gingival tissue, a preserved gingival papilla incision can be considered. 3, Flap to fully expose the diseased alveolar bone. 4.Cleaning and root surface leveling scrape the pathological tissue and combined epithelium in the bone pocket, and if an in-sulcus incision is used, the pocket epithelium and granulation tissue in the inner wall of the gingival flap should be trimmed, tartar removed, and the root surface leveled. Observe the morphology, type and size of the bone defect in the bone pocket. 5.Bone grafting will deliver the taken bone tissue or other implant material into the bone pocket, paying attention to the appropriate amount of implantation, flush with the bone pocket. 6.The soft tissue flap should be reset and sutured so that the gingival flap will cover the implant material tightly, and if necessary, the crown should be reset. When suturing, horizontal mattress suture or vertical mattress suture can be used to strengthen the fit of the gingival flap. 7.Periodontal plugging agent will be placed after the rinsing of the periodontal plugging area. 8, postoperative care is extremely important, especially the stability of the gingival flap and the prevention of postoperative infection is most important. After surgery, antibiotics can be given orally for one week and rinse with 9 or 12% chlorhexidine for at least 4 weeks. Generally, the stitches are removed 10 days after surgery, after which it is still necessary to review every 1 to 2 weeks to closely observe and remove plaque.