In daily clinical practise we frequently encounter situations in which the bone volume is insufficient for an ideal dental implant placement. Bone regeneration can provide the structural support necessary in these cases. Procedures such as sinus lifting and alveolar ridge augmentation have reached high levels of predictability and already are of major importance in implant practise. Interest for bone substitutes for alveolar ridge augmentation or preservation appears in the early 1980 ¿s alongside the development of endoosseous dental implants. Although first studies regarding bone substitutes dates from 1920 by Albee (Albee, 1920), until 1980 ¿s there are very few studies in reference this issue. From 1980 ¿s until nowadays an exponential number of studies about bone substitutes have been made. The reason for this increasing interest in bone substitutes stems from the fact that about 10- 20% of the patients that need treatments with dental implants, require bone regeneration procedures before implant placement. Moreover, more than 60% of the population in industrialized countries need dental prosthetic replacements (Peterson, 2006), ideally with implants. This is the reason why the market of dental implants is experiencing an increase of approximately 15% every year. Bone regeneration procedures are becoming an almost daily practice in dentistry all around the world as a result of the wide acceptance of dental implants as the ¿ideal ¿ option for oral rehabilitation. Bone regeneration procedures are critical for the success of dental implant treatments in cases where there is a deficiency in bone width and/or height. The cornerstone in these treatments is the use of bone substitutes to create a bone mantle that covers the screw to enhance implant stability and treatment outcome. In this chapter, we will discuss the different types of bone substitutes and recent developments achieved to enhance the outcomes of bone regeneration procedures with the newest available biomaterials. The term ¿bone graft ¿ was defined by Muschler (Bauer, 2000) as: ¿any implanted material that alone or in combination with other materials promotes a bone healing response by providing oteogenic, osteoinductive or osteoconductive properties ¿. An osteogenic material can be defined as one that has inherent capacity to form bone, which implies to contain living cells that are capable of differentiation into bone cells. An osteoinductive material 92 Implant Dentistry ¿ The Most Promising Discipline of Dentistry provides biologic signals capable to induce local cells to enter a pathway of differentiation leading to mature osteoblasts. An osteoconductive biomaterial provides a three-dimensional interconnected scaffold where local bone tissue may regenerate new living bone. However, osteoconductive biomaterials are unable to form bone or to induce its formation. Another property that is interesting to find especially in bone substitutes is biodegradability. This is defined as the capacity of degradation of a particle by two mechanisms principally; through a passive chemical degradation or dissolution, and through active cellular activity mediated by osteoclast and/or macrophages. Moreover, the biological properties of bone substitute biomaterials are also influenced by their porosity, surface geometry and surface chemistry. The events leading to bone healing and regeneration are influenced by all the variables mentioned above. These properties are related to the biomaterial itself, however, host factors such as bone quality, vascularity of the graft bed and tobacco addiction may also influence the final outcome of a bone regeneration procedure with a bone substitute.
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