RECOMBINANT BONE MORPHOGENETIC PROTEIN-2 ENHANCES BONE HEALING, GUIDED BY OSTEOPROMOTIVE E-PTFE MEMBRANES - AN EXPERIMENTAL-STUDY IN RATS

It has been shown earlier that it is possible to improve bone healing, to regenerate previously existing bone, and to create new bone by mea ns of an osteopromotive membrane technique. The present study addresse s the question of whether it is possible to combine this technique wit h a locally applied factor, stimulatory to osteogenesis. Circular tran sosseous 'critical size' defects in mandibles of rats were either impl anted with recombinant human bone morphogenetic protein type 2 (rhBMP- 2) or were left empty; half the number of implanted and half the numbe r of empty defects were covered with an expanded polytetrafluoroethyle ne (e-PTFE) membrane (GORE-TEX(R)). Results were evaluated after 12 an d 24 days of healing by a histomorphological scoring system. Implantat ion of rhBMP-2 alone resulted in bony bridging of the defect after onl y 12 days, but also in voluminous amounts of new bone outside the orig inal defect area. When rhBMP-2 was combined with membrane, newly forme d woven bone bridged the defect and the bone contour was maintained by the membrane. The combined treatment with membrane and rhBMP-2 demons trated a significantly better bone healing than with e-PTFE membrane a lone at both 12 days and 24 days of healing. It was concluded that rhB MP-2 has a strong osteoinductive potential and, in contrast to what wa s found earlier with other types of BMP preparations, this potential w as retained when combining the rhBMP-2 with the osteopromotive membran e technique, yielding better bone healing than with the membrane alone , and at the same time maintaining the bone contour. This combination may have important therapeutic applications for osseous healing and in reconstructive surgery. The study also shows the importance of an app ropriate carrier material when applying stimulatory substances to enha nce bone formation in combination with a membrane.