Hyaluronan supports recombinant human bone morphogenetic protein-2 inducedbone reconstruction of advanced alveolar ridge defects in dogs. A pilot study

Background: Prosthetic-driven implant dentistry requires predictable proced ures for alveolar ridge augmentation. The objective of this pilot study was to evaluate bone regeneration in mandibular, full-thickness, alveolar ridg e, saddle-type defects following surgical implantation of recombinant human bone morphogenetic protein-2 (rhBMP-2) in a novel hyaluronan (HY) sponge c arrier. This sponge was fabricated from auto-crosslinked HY. Methods: Alveolar ridge defects (similar to 15 x 10 x 10 mm), 2 per jaw qua drant, were surgically prepared in each of 3 young adult American fox hound s. Four defects were immediately implanted with rhBMP-2/HY. Three defects w ere implanted with rhBMP-2 in an absorbable collagen sponge (ACS) carrier ( positive control). The rhBMP-2 solution (1.5 ml at 0.2 mg/ml) was soak-load ed onto the HY and ACS sponges. Three defects were implanted with HY sponge s soak-loaded with buffer without rhBMP-2 (negative control), while 2 defec ts served as surgical controls. The animals were euthanized at 12 weeks pos tsurgery for histometric analysis. Results: Clinically, alveolar ridge defects receiving rhBMP-2/ACS exhibited a slight supracrestal expansion, while defects receiving rhBMP-2/HY were f illed to contour. In contrast, the HY and surgical controls exhibited ridge collapse. rhBMP-2/HY-treated defects exhibited a dense bone quality withou t radiolucent regions observed in defects treated with rhBMP2/ACS. The hist ometric analysis showed 100% bone fill for the rhBMP2/ACS defects and 94%, 58%, and 65% bone fill for the rhBMP-2/HY, HY, and surgical control defects , respectively. Conclusions: The conclusions are based on data from 2 of 3 animals in the s tudy. In one animal, no response to rhBMP-2 was observed with either carrie r, and the animal may have been a non-responder of unknown nature. With thi s limitation, the observations herein suggest that: 1) HY supports signific ant bone induction by rhBMP-2; 2) the rhBMP-2-induced bone assumes qualitie s of the immediate resident bone; 3) HY alone exhibits no apparent osteocon ductive potential; and 4) HY appears to resorb within a 12-week healing int erval in the absence or presence of rhBMP-2. Thus, HY appears to be a suita ble candidate carrier for rhBMP-2.