ABILITY OF COMMERCIAL DEMINERALIZED FREEZE-DRIED BONE ALLOGRAFT TO INDUCE NEW BONE-FORMATION

DEMINERALIZED FREEZE-DRIED BONE ALLOGRAFT (DFDBA) has been used extens ively in periodontal therapy. The rationale for use of DFDBA includes the fact that proteins capable of inducing new bone; i.e., bone morpho genetic proteins, can be isolated from bone grafts. Commercial bone ba nks have provided DFDBA to the dental practitioner for many years; how ever, these organizations have not verified the osteoinductive capacit y of their DFDBA preparations. The aim of this study was to determine the ability of commercial DFDBA preparations to induce new bone format ion. DFDBA with particle sizes ranging from 200 to 500 mu m was receiv ed from six bone banks using various bone production methods. Differen t lots of DFDBA from the same tissue bank were sometimes available. A total of 14 lots were examined. The surface area of bone particles in each sample was measured morphometrically and the pH of a solution con taining the particles after suspension in distilled water determined. Samples from each DFDBA lot were implanted intramuscularly (10 mg) or subcutaneously (20 mg) into three different animals and tissue biopsie s harvested after 4 weeks. One sample from each tissue bank was implan ted and harvested after 8 weeks. At harvest, each area where DFDBA had been implanted was excised and examined by light microscopy. The abil ity of DFDBA to produce new bone was evaluated and the amount of resid ual bone particles measured. The results show that bone particles from all tissue banks had a variety of shapes and sizes, both before impla ntation and after 1 or 2 months of implantation. The pH of particle su spensions also varied between batches, as well as between tissue banks . None of the DFDBA induced new bone formation when implanted subcutan eously. Intramuscular implants from three banks induced new bone forma tion after 1 and 2 months. DFDBA from two banks caused new bone format ion only after 2 months. However, DFDBA from one bank did not induce n ew bone at all. Particle size before implantation correlated with part icle size after implantation. However, particle size did not correlate with ability to induce bone. The results show that commercial DFDBA d iffers in both size and ability to induce new bone formation, but that the two are not related. The study also indicates that wide variation in commercial bone bank preparations of DFDBA exist and that ability to induce new bone formation also varies widely. Furthermore, the resu lts suggest that methods or assays for evaluating the ability of DFDBA to induce new bone should be developed and standardized.