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 2 ). 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 2 , p = 0.003) and ACS (1.8 ± 0.8 vs. 1.0 ± 0.6 mm 2 , 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.