rhBMP-2 for Alveolar Bone Reconstruction in Implant Dentistry.

rhBMP-2 for Alveolar Bone Reconstruction in Implant Dentistry.
Dental News
2005
Ulf ME Wikesj??, Oliver Hanisch, Michael J Danesh-Meyer
INTRODUCTION
Surgical placement of dental implants is primarily governed by the prosthetic design and secondarily by the morphology and quality of the alveolar bone. Often, implant placement may be difficult, if at all possible, due to alveolar ridge aberrations. In consequence, prostheticly dictated dental implant positioning often entails reconstruction or augmentation of the alveolar ridge. In this review we discuss questions regarding extensively evaluated and currently practiced bone grafting in implant dentistry. We then focus the discussion to preclinical studies applying recombinant human bone morphogenetic protein-2 (rhBMP-2) technology to alveolar and peri-implant defects.
BONE GRAFTING
Benefits from the osteogenic potential of autograft bone, the treatment of choice or ǃ?gold standardǃ? for skeletal reconstruction, are restricted due to limited donor tissue resources and morbidity besides the possibility that bone modeling may result in undesirable alterations in tissue volume and geometry. In perspective, allogeneic or xenogeneic bone derivatives such as decalcified or undecalcified, freeze-dried, allogeneic bone preparations or xenogeneic bone mineral preparations, commonly considered osteoconductive biomaterials, appear attractive to support bone reconstruction in the craniofacial skeleton. Briefly, osteoconduction delineates a property of a biomaterial that enhances ingrowth of bone into a defect from osteogenic tissue sources and is usually attributed to the geometry, porosity, and bioreactivity of the material.
Considerable work concerning the efficacy and safety of allogeneic bone preparations has been presented. It has been suggested that allogeneic bone, freeze-dried and decalcified, may support regeneration of alveolar bone (1). Nevertheless, a rapidly increasing body of evidence questions the clinical relevance, the osteoconductive and regenerative potential of such bone preparations. In brief, histologic studies evaluating freeze-dried, decalcified, allogeneic bone in a variety of models including long bones, calvaria, and the alveolar ridge provide little, if any, evidence of a short- or long-term benefit of these materials (2, 3). Xenogeneic bone mineral preparations appear to incorporate into bone however their slow resorption rates have impact on the quality of the newly formed bone and ultimately their clinical relevance (4). Moreover, public perception of allogeneic or xenogeneic cadaver materials reduces their acceptance for elective procedures. Thus, potential for immunologic reactions, fear of disease transmission, and uncertain outcomes, limit the acceptance and utility of allogeneic or xenogeneic bone derivatives.
Ceramic and polymeric bone substitutes, potentially osteoconductive, have also been suggested in the reconstruction of bone. A variety of resorbable or non-resorbable biomaterials including calcium-based ceramics, bioactive glass, and synthetic polymers are commercially available for alveolar reconstruction (5). In selection of ceramic or polymeric bone substitutes, the clinician must carefully consider mechanical and biological qualities of these materials. Early resorption of an implanted material must not significantly interfere with bone formation. Late resorption must not significantly compromise bone maintenance. It appears critical that any implanted biomaterial,, whether sourced from allogeneic or xenogeneic bone, or being of ceramic or polymeric origin, does not compromise bone formation by obstructing the wound space, negating or delaying the native osteogenic potential of the site, nor should its long-term residence compromise mechanical properties of bone, including load-bearing and dental implant osseointegration.