**4. Bone augmentation techniques**

#### **4.1. Sinus lifting**

**3.2. Osteoinduction**

144 Tissue Regeneration

**3.3. Osteoconduction**

**3.4. Creeping substitution**

tion process and acts as an osteoinductive agent.

growth factors, to create inductive effects [22].

Osteoinduction is an active process in which the bone graft causes the bone-forming cells to penetrate the recipient region and stimulates them to form new bones. Osteoinduction refers to the ability of the graft to send a signal to attract, proliferate, and differentiate early-lineage cells (e.g., mesenchymal stem cells or osteoprogenitor cells) into bone-forming cells, resulting in the formation of a mineralized bone. Bone morphogenetic proteins (BMPs) support these signals. BMP is measured as the amount of picograms in the normal bone. In recent studies on osteoinduction, Urist et al. isolated BMP, a soluble glycoprotein. They described BMP as a growth factor of the transforming growth factor (TGF)-β family and as an inductive agent. They also reported that at least 15 different types of BMPs were found, and the most important were BMP-2 and BMP-7 [23]. BMP is naturally released during trauma or the regenera-

Demineralized bone matrix (DBM) allograft materials have osteoinductive healing mechanisms. DBM allografts can provide a matrix for bone cells to infiltrate and produce bone. Its healing mechanism manifests through osteoinductive pathways, and bioactive molecules

Osteoconduction is described as the growth of a superficial bone on a surface. Osteoconductive materials are biocompatible and have an osteoconductive surface: on its pores, in its ducts, or in its tubes. Materials with osteoconductive properties form a matrix and guide osteogenesis. Grafts with osteoconductivity have no bone formation capacity and can only function as a roof for bone formation. If osteoconductive materials are placed in ectopic areas such as subcutaneous bones, bone formation does not occur and the material remains unchanged or resurfaced [22]. Examples of osteoconductive properties are autografts, allografts, xenografts, calcium sulfates, calcium phosphate cements, ceramics, collagen, and synthetic polymers. It is also known that bone graft materials may be supplemented with materials such as exogenous

Creeping substitution indicates the movement of new tissues through channels made by blood vessels invading a transplanted bone. The dynamic healing and reconstructive process of bone transplantation was described by Axhausen in 1907; he reported that bone transplants undergo necrosis. The necrotic bone is then replaced by the new bone via creeping substitution [25].

Improvement of the graft material differs according to graft type in terms of duration and content. Vascular support in the recipient region and the survival rate of cells in the graft have a direct impact on graft recovery. Morphologically, the cortical bone, which is the tight structure around the haversian and Volkmann channels, consists of circular, parallel, and interstitial bone lamellar. The cancellous bone is porous and trabecular in shape and contains the bone marrow. There is a less surface area in the cortical bone than in the cancellous bone; therefore,

stimulate mesenchymal cells to differentiate into bone-forming cells [24].

Prostheses that are supported on maxillary dental implants are now the optimum way to give patients an admissible quality of life. In cases with a vertical insufficient alveolar bone, a maxillary sinus lift with a bone graft using a crestal or lateral approach is needed. Elevation of the sinus floor permits the correct number and length of endosseous implants to be applied for adequate mechanical support of the atrophic posterior maxilla [27].

Previous studies proved that dental implants related to maxillary sinus augmentation have a satisfactory long-term success and survival rate [28]. Implant application may be simultaneously combined with maxillary sinus lifting procedure as a" one-stage" surgery, or sinus lifting may be conducted at first, and implants are then applied as a" two-stage" operation. There are many options for graft material to augment the maxillary sinus. Autogenous grafts can be harvested from the chin and ramus intraorally or iliac crest, calvarium, and tibia extraorally. The disadvantages of autogenous grafts are resorption rate and morbidity. Allografts (cadaveric bone) are harvested and different techniques such as irradiation and freeze-drying are used to reduce antigenicity. Allografts are found in tissue banks. Xenografts consist of anorganic bovine or equine bone. The organic components of these types of grafts are chemically removed and a mineral scaffold is obtained. Alloplasts are synthetic materials; there are many types of structures of alloplastic grafts such as micro- or macroporous, dense, amorphous, or crystalline grafts. Structure and porosity directly influence the performance of the material [29].

#### **4.2. Socket preservation**

Following tooth extraction, alveolar bone remodeling begins by means of vertical and/or horizontal bone resorption [30] so that a proper prosthetic and esthetic position of dental implants can be influenced. Alveolar socket preservation techniques have been introduced to conserve the alveolar bone vertically and horizontally [31].

Socket preservation could be considered when:


There are various graft materials used in socket preservation surgery such as autografts, allografts, xenografts, alloplasts, or platelet concentrates. Allogenic bone is described as the

**Figure 1.** Extraction of lateral incisor.

most suitable material to obtain optimum results for socket preservation techniques. Freezedried bone allograft (FDBA) and demineralized freeze-dried bone allograft (DFDBA) are used in socket preservation techniques. Recently, platelet concentrates have been widely used for socket preservation. The platelet concentrates contain a high concentration of growth factors, such as PDGF, TGF-β, IGF, and VEGF, as well as anti-inflammatory molecules, such as IL-1β, IL-4, IL-6, and TNF-α, which accelerate the healing process. This results in better bone repair and regeneration [33].

Primary closure of the flap is important and should be performed if possible. The other methods to seal the surgery site are free gingival grafts, collagen membranes, or nonresorbable membranes [34]. The socket-shield technique is currently performed. Applying this technique, a buccal part of the tooth root is retained in the alveolar socket during tooth extraction. This is done to prevent the resorption of the vestibular bony lamella [35].

Several studies have reported that the socket preservation technique is very successful and useful compared to nongrafted sockets [31]. If immediate implantation is not possible, the socket preservation technique should be used to increase esthetic outcome as well as alveolar bone quality (**Figures 1**–**4**) [35].

**5. Types of bone grafting materials**

**Figure 4.** Post-op 6 months.

**Figure 3.** Sutures and closure.

the formation of the new bone should balance with resorption [36].

Graft materials may be synthetic or natural materials that are placed in a biological environment for reconstructive purposes, and are prepared to be accepted by the surrounding tissues. The most commonly used biomaterials include autografts, xenografts, allografts, and alloplasts. Ideally, the material for bone regeneration should be able to form a new bone, and

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The first biomaterials used for grafting areas with bone deficiencies were autografts. Autogenous bone is considered the gold standard for grafting biomaterials for its three main properties: osteogenesis, osteoinduction, and osteoconduction. Advantages of autogenous bone grafts include early vascularization, osteoinductive properties, low cost, and minimal morbidity. Recent research on cortical bone chips revealed that the paracrine effect of bone chips has a significant impact on bone regeneration. Autogenous bone can be harvested near

**Figure 2.** Applying of bone graft material.

Hard Tissue Regeneration Treatment Protocols in Contemporary Oral Surgery http://dx.doi.org/10.5772/intechopen.74944 147

**Figure 3.** Sutures and closure.

most suitable material to obtain optimum results for socket preservation techniques. Freezedried bone allograft (FDBA) and demineralized freeze-dried bone allograft (DFDBA) are used in socket preservation techniques. Recently, platelet concentrates have been widely used for socket preservation. The platelet concentrates contain a high concentration of growth factors, such as PDGF, TGF-β, IGF, and VEGF, as well as anti-inflammatory molecules, such as IL-1β, IL-4, IL-6, and TNF-α, which accelerate the healing process. This results in better bone repair

Primary closure of the flap is important and should be performed if possible. The other methods to seal the surgery site are free gingival grafts, collagen membranes, or nonresorbable membranes [34]. The socket-shield technique is currently performed. Applying this technique, a buccal part of the tooth root is retained in the alveolar socket during tooth extraction.

Several studies have reported that the socket preservation technique is very successful and useful compared to nongrafted sockets [31]. If immediate implantation is not possible, the socket preservation technique should be used to increase esthetic outcome as well as alveolar

This is done to prevent the resorption of the vestibular bony lamella [35].

and regeneration [33].

**Figure 1.** Extraction of lateral incisor.

146 Tissue Regeneration

bone quality (**Figures 1**–**4**) [35].

**Figure 2.** Applying of bone graft material.

**Figure 4.** Post-op 6 months.
