| Abstract: | The principle of Guided Bone Regeneration (GBR) can be used for Ridge Augmentation. These case illustrations describe the technique using Autogenous Cortico-Cancellous Bone Grafts and stabilization with Miniscrews and placement of a GTAM Barrier Membrane. Nyman et al (1990) published the first report of enlargement of a reduced alveolar ridge. Becker & Becker, Jovanovic, Buser et al have documented successful regeneration of such ridges. A study by Lang et al established that: 1. An undisturbed healing period of at least six months is required for optimal bone regeneration. 2. Smaller defects (less than 70 mm.3) regenerate almost completely. 3. Larger defects (greater than 90 mm.3) regenerate 90-93 percent and bone grafts may enhance success in larger defects. 4. Premature membrane removal will result in incomplete regeneration. Buser et al have described the technique of GBR in detail. They found the creation and maintenance of a secluded space is essential for successful outcome with GBR procedures. This space allows for the in growth of osteogenic cells so that bone regeneration is undisturbed by competing non-osteogenic soft tissue cells. Space-making defects such as extraction sockets are simple to treat, but localized ridge augmentation may be difficult because the membrane is not supported by bony walls. E-PTFE membranes have been reinforced with titanium struts and mini screws have been developed as a way of dealing with membrane collapse. Buser et al began to utilize autogenous bone grafts to support the membrane and to act as an osseoinductive scaffold for bone regeneration. They utilized a cortico-cancellous block graft in the centre of the augmentative area with smaller chips to fill in the periphery. The cortical portion of the graft re-establishes the buccal cortex and the cancellous portion is placed against the host bone. The host bone is perforated to open the marrow spaces. Placement of membrane protects the bone graft (up to 50 percent of grafted bone is lost through resorption in augmentation procedures where membrane is not used). |
