THE TIME-COURSE OF THE INDUCTION OF REPARATIVE DENTIN FORMATION IN MONKEYS BY RECOMBINANT HUMAN OSTEOGENIC PROTEIN-1

Recombinant human osteogenic protein-1 (hOP-1, BMP-7) induces cartilage and bone formation when implanted in extra- and intraskeletal sites in vivo. rOP-1 also preserves pulp vitality and stimulates reparative dentine formation when placed on partially amputated vital dental pulp tissue. The amount of dentine formed in 6 weeks was earlier found to be proportional to the total amount of rOP-1/carrier placed on the pulp and the capacity of the pulp to respond to rOP-1 appeared to be independent of the amount of coronal pulp removed. This reparative dentine was not completely mineralized after 6 weeks healing. Experiments were now made to determine the capacity of hOP-1 to preserve the vitality of and induce reparative dentine in vital radicular pulps. The extent of tissue mineralization present after 1, 2, 4 and 6 months' healing time in permanent monkey teeth was assessed. Radicular pulp vitality was maintained, reparative dentine formed, and mineralization was nearly 75% complete after 1 month and more than 95% after 4 months. The effects of irrigating the exposed pulps with EDTA, sodium hypochlorite or saline were also compared. Significantly more sodium hypochlorite-treated pulps became non-vital and the root canals of all the non-vital teeth contained bacteria at the time of sacrifice.