Comparative Clinical and Radiographic Evaluation of Demineralized Freeze-dried Bone Allograft With and Without Decortication in the Treatment of Periodontal Intrabony Defects - a Randomized Controlled Clinical Study.

INTRODUCTION Periodontitis is a multifactorial infectious disease with microbial plaque as initiator that triggers inflammatory response in the periodontal tissue. As the disease progresses, symptoms may include bleeding gums, periodontal abscesses, increased tooth mobility due to the loss of bone support, tooth migration, exposure of the root surface, and tooth loss. Current periodontal therapy is directed towards establishing a healthy periodontium by attempting to resolve the tissue inflammation induced by bacterial plaque and its products and the restitution of the anatomic defects caused by the disease process. There are many outcomes possible from the periodontal therapy depending upon the goals, the type of therapy, and the methods utilized to evaluate it. These can range from halting the destructive process, maintaining an area to repair a defect and/or regeneration.

Melcher described the concept of selective cell repopulation of defects to enhance healing.The guided tissue regeneration (GTR) technique excludes faster growing epithelial and connective tissue cells with barriers and bone grafts to allow slower moving pluripotential and osteogenic cells to repopulate the treated site. To attain horizontal and/or vertical bone augmentation beyond the envelope of skeletal bone, four principles need to be met: primary wound closure, angiogenesis to provide necessary blood supply and undifferentiated mesenchymal cells, space maintenance and stability of the blood clot .The ultimate goal of the regenerative periodontal therapy is to restore the lost periodontal tissues including cementum, periodontal ligament and alveolar bone.

The current regenerative therapy includes the use of bone grafts, guided tissue regeneration (GTR), bioactive agents like Enamel matrix derivative (EMD) and laser assisted regeneration. The clinical periodontal regenerative treatments focus on the utilization of bone grafts that can be obtained from the same individual (autografts), from different individual of the same species (allografts) or from a different species (xenografts). Apart from these synthetic bone grafts are also available (alloplasts).

Allografts are bone grafts taken for transplantation from one human to another. There are two types of allografts available including freeze-dried bone allograft and demineralized freeze-dried bone allograft (DFDBA). Demineralized freeze-dried bone allograft is a graft that possesses osteoconductive and osteoinductive properties. Demineralization process of the graft exposes the bone inductive properties located in the bone matrix such as bone morpogenetic protein-2(BMP2) and bone morpogenetic protein-7 (BMP 7) that aid in mesenchymal cell migration, attachment and osteogenesis when implanted in well vascularised bone. It has shown to regenerate bone as well as cementum and periodontal ligament in treatment of periodontal osseous defects at the same time eliminates the need for a second surgical site. When used for periodontal regeneration, DFDBA may not only lead to clinical improvements in terms of pocket probing depth (PPD) reduction and gain of clinical attachment level (CAL), but also lead to formation of new connective tissue attachment and new alveolar bone.

Several authors have advocated the use intramarrow penetration (IMP), also known as decortication, as a part of guided bone regeneration procedure. Osteoblasts that form new bone are derived from periosteum, endosteum, and undifferentiated pluripotential mesenchymal cells in the bone marrow. After the elevation of mucoperiosteal flap when the barrier is placed, the contribution of periosteum to GBR procedure is lost. Along with this, a bone graft placed on the cortical bone also interferes with the entry of undifferentiated pluripotential mesenchymal cells from the endosteum and bone marrow towards the GBR-treated site.Therefore drilling holes through cortical bone into more vascular cancellous bone induces bleeding and organised clot releases cytokines and growth factors which attracts the blood vessels, osteoblasts, and pluripotential cells to the grafted sites. It also enhance the physical connection between the bone graft and recipient site to improve its stability and provide firm linking for newly generated bone.Studies have shown that open flap debridement (OFD) combined with decortication produces positive result outcomes in regenerative periodontal treatment.