Allogeneic Bone Matrix Research Articles

Effect of preimplantation treatment on the bone-forming potential of decalcified allogeneic and xenogeneic bone-matrix implants

Bone-forming property of 0.6 M HCl decalcified (a) allogeneic bone matrix preserved in 70% alcohol, (b) allogeneic bone matrix preserved in anaesthetic ether, (c) allogeneic 'Ossein' provided by the Leather Research Institute, Madras, and (d) xenogeneic bone-matrix preserved in alcohol was studied by fitting the implants in surgically created complete circumferential osteo-periosteal gaps in the ulna of rabbits. Bone formation was assessed radiologically, macroscopically, histologically, and by tetracycline fluorescence up to 16 postimplantation weeks. Successful bridging of the gap by new bone formation was observed in 75% of (a) and 28.6% of (d) preserved up to 2 weeks. Ether-preserved implants did not induce bone formation. The 'Ossein' implants remained as inert material neither invaded by host cells nor inducing any bone formation. The xenogeneic implants exhibited local immune response which was probably responsible for poor osteogeneic response. Bone forming quality of bone-matrix implants appears to be influenced by the chemical treatment during preparation and preservation, host cellular response and immune reaction invoked by the implant.

Experimental osteogenesis with decalcified allogeneic bone matrix in palatal defects

Decalcified allogeneic bone matrix grafts were implanted in fresh palatal defects in six monkeys and chronic palatal defects in seven dogs. The chronic palatal defects were created with an air drill and with insertion of silicone rubber in palatal defects for 4 weeks. Clinical, histologic, fluorescent, and radiologic studies reveal that DABM grafts form new bone, thus resulting in bony union of the host bone to new bone. The DABM grafts were not rejected by the host tissue; rather, they were resorbed and replaced by new bone. It is speculated at this time, from the present results, that DABM grafts may have a clinical implication for patients with cleft palate.

Demineralization of bone transplants in vivo

A standard experimental model was designed by creating midfibular fracture gaps in rats, for the study of grafts of decalcified allogeneic bone matrix (DABM), fresh autologous bone, fresh allogeneic bone, and decalcified xenogeneic bone matrix (DXBM). The results reveal that DABM implants were accepted by the host in fresh and chronic fibular gaps. There was a gradual increase in calcium concentration, which reached normal levels by the eighth postoperative week at fracture gap sites. DXBM grafts demonstrated very small concentration of calcium after 4 weeks, which was mainly due to formation of callus around the grafts; and 55 per cent of these grafts were rejected, as evidenced by exudate and exfoliation. Fresh autologous and fresh allogeneic bone transplants demonstrated a fall in calcium concentration in the initial 3-week intervals, then a gradual increase in mineralization, and the attainment of normal levels by the eighth postoperative week. All autologous bone grafts were accepted, whereas 45 per cent of fresh allogeneic bone grafts were rejected from the mid-fibular implanted sites. The study with autologous bone transplants was repeated, and the implanted bone was isolated from new bone for calcium estimation at various postoperative intervals. The results revealed gradual decrease in calcium concentration up to 4 weeks, and the later intervals could not be estimated because of difficulty in separation of implanted bone from the new bone. The results of these experiments suggest that calcified bone grafts (autologous or allogeneic) undergo partial or complete decalcification in tissues after implantation. Since this decalcification of bone could be accomplished in vitro, it would appear that the DABM grafts are worthy of trials in human osseous deformities.

Decalcified allogeneic bone matrix implantation in joint spaces of rats

Decalcified allogeneic bone matrix (DABM) grafts were investigated in joint spaces of rats. In the first experiment, DABM grafts were implanted after early postnatal unilateral condylectomies in 1-day-old albino rats. Similarly, in the second experiment, DABM grafts were placed after excision of the fibular heads at the fibulo-femur joints in adult albino rats. The results indicate that DABM grafts act as a center of mandibular growth, do not interfere with growth of the mandible, and form new bone and condyle (new joint) of the same size and shape without resulting in ankylosis. In the controls, in which DABM grafts were not implanted, there was no new bone formation; and joint spaces were filled with fibrous connective tissue and resulted in malgrowth of the mandible in young rats. The clinical, radiologic, and histologic evidence demonstrates the regeneration of new bone in the formation of the heads of fibulae in adult rats. The DABM grafts were resorbed and replaced by new bone and did not seem to evoke an immunologic response.

Maintenance of acrylic teeth with decalcified allogeneic bone implanted into fresh extraction sites in monkeys and dogs

Sixty-five acrylic resin tooth implants were placed in fresh extraction sockets in six monkeys and sevev dogs. Twenty-one of these implants were surrounded with decalcified allogeneic bone matrix. Clinical, radiologic, fluorescent, and histologic studies indicated that, with the use of DABM grafts, the plastic tooth implants were maintained firm within the experimental period of 22 weeks.

Experimental osteogenesis in periapical areas with decalcified allogeneic bone matrix

Decalcified allogeneic bone matrix grafts were implanted in fourteen teeth after pulpotomy, in twenty root canals after pulp extirpation, and in the periapical areas of forty-eight teeth after apicoectomy. These procedures were carried out in five dogs and three monkeys. Results of the present investigation reveal that DABM grafts stimulate osteogenesis and cementogenesis. Although present data are insufficient, it can be speculated that DABM grafts would result in physiologic seal at the apical foramen of apicoectomized teeth with new bone and cementum. Thus, this increased osteogenesis and cementogenesis will prolong the survival of nonvital teeth in human beings.

Osteoinduction and Osteogenesis in Implants of Allogeneic Bone Matrix Influence of Somatotropin, Thyrotropin, and Cortisone

Osteoinduction and Osteogenesis in Implants of Allogeneic Bone Matrix Influence of Somatotropin, Thyrotropin, and Cortisone

Bone induction in experimental periodontal bony defects in dogs with decalcified allogeneic bone matrix grafts: A preliminary study

Decalcified allogeneic bone matrix grafts have been studied in periodontal bony defects in twenty-seven dogs. DABM grafts were resorbed and replaced by new bone. There occurred union of new bone to the cemental (tooth) surface (ankylosis). Clinical, radiologic, fluorescent, and histologic studies revealed that such grafts could ultimately be of use in human beings, especially since these grafts are not rejected and, to our knowledge, do not cause any immunologic response.

Stimulation of new bone formation on intact bones by decalcified allogeneic bone matrix

The results of the present experiments indicate that grafts of allogeneic bone matrix are not rejected and that they induce formation of new bone at the site of their placement. The fact that decalcified allogeneic bone matrix induces little or no immune response suggests that it has a very weak, if any, antigenic activity, but at present there is no really clear explanation for the fact that this material does not elicit such a response.

Grafts of decalcified allogeneic bone matrix promote the healing of fibular fracture gaps in rats.

From the Oral Pharmacology Laboratory, Division of Oral Biology. Boston University School of Graduate Dentistry; and Ihc Dcparimcnt of Pharmacology, Boston University School of Medicine, Boston, Massachusetts. *From the Oral Pharmacology Laboratory, Division of Oral Biology. Boston University School of Graduate Dentistry; and Ihc Dcparimcnt of Pharmacology, Boston University School of Medicine, Boston, Massachusetts; Boston University School of Graduate Dentistry, 80 East Concord Street, Boston, Massachusetts 02118.