The role of stem cells in oral bone regeneration

Bone defects in the oral cavity differ greatly, ranging from limited alveolar bone loss to large-scale bone atrophy. A “jaw (bone) defect” is defined as the lack of bone volume where it should normally exist. A variety of reasons can cause jaw deformities such as extractions/ tooth loss, periodontitis, periapical infections, injuries due to facial trauma, tumors or cyst resections, congenitally missing teeth or developmental conditions (cleft palate defects), osteomyelitis, osteoradionecrosis and druginduced osteonecrosis. The most common cause is the post-extraction alveolar ridge collapse, which is inevitable and leads to bone loss in both horizontal and vertical dimensions. The above is clinically relevant when implant replacements are to be inserted as their position in the jaws should be driven by the restorative plan. Regardless of the cause of jaw deficiencies, reconstruction of the maxilla and the mandible is imperative for the return to form and function. Reconstructive jaw surgery may involve a multitude of different bone grafting materials such as autografts, allografts, xenografts and alloplasts. Autologous bone grafts are considered to be the gold standard for bone regeneration because of histocompatibility and their osteogenic, osteoconductive and osteoinductive properties. However, autografts show some disadvantages due to their limited supply, donor-site morbidity and potential infections. On the other hand, allografts and xenografts do not have the problem of limited supply and do not require a donor site but they have poor osteoinductive properties due to the absence of cell populations. To overcome these difficulties, new advanced techniques have been employed and one of the most promising is the use of stem cells. By the term “stem cells” we define the cells with the ability to grow into anyone of the human body’s more than 200 cell types, responsible for the foundation of each and every organ and tissue. They have two defining characteristics; the ability of unlimited self-renewal and the ability to differentiate into specialized adult cell type with specific functions, when stimulated by both external and internal signals. Abstract