Volume-Stable Collagen Matrix as a Recombinant Human Bone Morphogenetic Protein-2 Carrier for Maxillary Sinus Augmentation: An Experimental In Vivo Study

Aim: To test the hypothesis that a volume-stable collagen matrix (VCMX) can serve as an effective rhBMP-2 carrier for bone regeneration while compensating for the volume instability of absorbable collagen sponge (ACS). Materials and methods: (i) rhBMP-2 release kinetics from VCMX and ACS were measured over 7 days by enzyme-linked immunosorbent assay. (ii) Bilateral sinus augmentations were performed in 15 rabbits using either VCMX or ACS, with or without rhBMP-2. After 4 weeks, radiographic and histological analyses were conducted. Results: The overall release patterns between VCMX and ACS did not differ significantly, although VCMX showed a delayed peak release (at 3 h) compared to ACS (at 10 min). Three-dimensional radiographic analysis showed greater volumetric gains in VCMX groups than in ACS groups, regardless of rhBMP-2 loading. Histologically, VCMX/rhBMP-2 group exhibited the largest total augmented area (13.1 ± 2.9 mm). The use of rhBMP-2 led to significant increases in new bone area for both VCMX (3.9 ± 1.1 vs. 1.6 ± 1.3 mm, p = 0.003) and ACS (1.8 ± 0.8 vs. 1.0 ± 0.6 mm, p = 0.035). Notably, the proportion of new bone in the total augmented region was comparable between the VCMX/rhBMP-2 and ACS/rhBMP-2 groups (p > 0.05). Conclusion: rhBMP-2-loaded VCMX enhances bone regeneration in sinus augmentation, suggesting that its volume maintenance may contribute to the improved clinical and radiographic outcomes.