Sinus augmentation using rhBMP-2/ACS in a mini-pig model: Influence of an adjunctive ceramic bone biomaterial

Background: Recombinant human bone morphogenetic protein-2 in an absorbable collagen sponge carrier (rhBMP-2/ACS) has been shown to support significant bone formation when used to augment the maxillary sinus for implant dentistry. Nevertheless, bone biomaterials have been suggested to extend rhBMP-2/ACS with limited support of the merits of such approaches. Objectives: To evaluate local bone formation/dental implant osseointegration following implantation of rhBMP-2/ACS combined with a ceramic bone biomaterial using a mini-pig sinus augmentation model. Methods: Twelve adult Göttingen mini-pigs received rhBMP-2/ACS (rhBMP-2 adjusted to 0.43 mg/cc) alone or combined with an off-the- shelf biphasic ceramic (15%/85% HA/ß-TCP) biomaterial at 3:1, 1:1 and 1:3 ratios randomized to contra-lateral maxillary sinus sites yielding rhBMP-2/ACS fractions of 100%, 75%, 50% and 25%, respectively. A 4-cc implant volume was used for all sites. Two threaded dental implants (ø4.0 × 11.5 mm) were placed at each site. The animals were euthanized at 8 weeks for histologic analysis. Results: Surgical execution and healing were generally uneventful, infraorbital local swelling was observed in all animals until suture removal. rhBMP-2/ACS combined with the ceramic biomaterial did not significantly enhance local bone formation (range 9.0 ± 1.5 to 9.7 ± 2.1 mm) compared with rhBMP-2/ACS alone (8.6 ± 1.1 mm; p > 0.05). Variations in rhBMP-2/ACS to ceramic matrix ratios yielding rhBMP-2 doses approximating 0.4, 0.9, 1.3 and 1.7 mg/sinus did not appreciably influence bone formation/osseointegration. Conclusions: Whereas rhBMP-2/ACS supports significant bone formation/osseointegration in the mini-pig sinus augmentation model and thus appears an effective alternative for sinus augmentation procedures, adding a ceramic biomaterial to rhBMP-2/ACS does not produce meaningful biological advantages.