Block augmentation is a technique developed for the reconstruction of the severely resorbed alveolar ridge or for the regeneration of complex defects in a two-stage approach for Guided Bone Regeneration. Blocks are fixated with osteosynthesis screws and edges should be smoothened with appropriate instruments to avoid soft tissue irritation. An appropriate soft tissue management that allows a tension-free wound closure is of utmost importance. Blocks can be covered with various bone grafting materials (e.g., cerabone®, maxgraft® granules or maxresorb®) and barrier membranes (e.g., Jason® membrane or collprotect® membrane) to fill remaining gaps and protect the site from resorption. Although the adjustment of the block shape prior to insertion can be relatively time consuming, this procedure provides a stable implant bed after a healing time of about six months.
Autologous bone blocks
According to the classical concept, autologous bone blocks are harvested from intraoral (e.g., mandibular symphysis, mandibular ramus, retromolar area, or maxillary tuberosity) or extraoral regions (typically the Cresta Iliaca). After block harvesting, the donor site can be filled with a collagen sponge (collafleece®) to support hemostasis. Autologous bone is a good scaffold for bone regeneration; however, the need for a second surgical site often results in an increased morbidity and post-operative pain as well as a higher risk of infection and complications. These disadvantages, together with the limited availability of autologous bone, prompted the development of various biomaterials.
Allogenic bone blocks
For experienced oral and maxillofacial surgeons, allograft bone blocks for block augmentation are the only real alternative to harvesting patient’s own bone. maxgraft® blocks are particularly suitable for block augmentation due to the flexibility of the material based on the unique production process. maxgraft® blocks retain their collagen matrix and the natural biomechanical properties of the bone matrix; this is the basis for the excellent handling properties of this material.
In addition, smoothing of sharp edges as well as covering of the bone block with a collagen membrane (e.g., Jason® membrane, collprotect® membrane) can help to prevent soft tissue perforation and ensure an undisturbed healing. The covering of the block with a particulate, slowly resorbable bone grafting material (e.g., cerabone®) can help to prevent a too-fast resorption. For contouring and smoothening the surface contours, also other grafting materials (e.g., maxresorb® or maxgraft® granules) can be used according to the patient’s and surgeon’s preferences.
Customized allogenic bone blocks
maxgraft® bonebuilder offers the possibility to avoid the time-consuming shaping of the bone block. Based on CT/CBCT scans of the patient, the bone block is virtually designed using the latest 3D CAD/CAM (computer-aided design/computer-aided manufacturing) technology.
Xenogenic/alloplastic bone blocks
In countries where allogenic bone blocks are not available, also purely mineral bovine (cerabone®) or synthetic (maxresorb®) bone blocks might be an alternative to autologous bone blocks. However, block augmentation with these bone substitutes is a challenging technique, only suitable for surgeons with prior experience with such materials.