Osteoinductive ability of human allograft formulations

Bone graft materials are needed in periodontics that are osteoinductive, have good handling characteristics, and have physical properties that provide appropriate stiffness for the treatment site. Demineralized freeze-dried bone allograft (DFDBA), also called demineralized bone matrix (DBM), is osteoinductive but requires a carrier to meet the other clinical objectives, thereby decreasing the DBM content per volume of the bone graft material. The present study determined whether the DBM content of a carrier formulation is an important variable with respect to its effectiveness as an osteoinductive material.

The immunocompromised Nu/Nu mouse-muscle implantation assay of osteoinductivity was used to test human DBM formulated with hyaluronic acid (HY) and cancellous and cortical bone granules from the same donor: DBM alone (11 mg); DBM (11 mg):HY, 55:45, weight/weight (wt/wt); DBM (6.4 mg):HY, 32:68, wt/wt; DBM mixed with cortical and cancellous bone chips 1:4 (DBMC) (11 mg total, of which 2.2 mg was DBM); DBMC (11 mg):HY, 55:45, wt/wt; heat-treated DBM (11 mg); HY alone; and positive-control DBM (11 mg). Osteoinduction was scored using a qualitative scale and by histomorphometry.

Results showed that all DBM was osteoinductive and the addition of HY did not change this as long as the amount of DBM used was held constant. The reduction in the absolute amount of DBM resulted in a reduced osteoinduction score, reduced ossicle area, and reduced new bone formation. The addition of HY also caused a decrease in the amount of residual non-vital bone particles, particularly when DBMC was implanted. Results were donor dependent.

This study showed the importance of DBM content and donor variability in osteoinductivity of DBM formulations with improved handling and stiffness characteristics.