Regeneration of Chronic Alveolar Vertical Defects Using a Micro Dosage of rhBMP-2. An Experimental In Vivo Study.

OBJECTIVE: The objective of this study is to compare the effect of the location of recombinant human bone morphogenetic protein 2 (rhBMP-2) from the native bone and the periosteum for vertical alveolar bone augmentation. MATERIALS AND METHODS: Mandibular, chronic, standardized, bilateral, and vertical defects in 12 beagle dogs were evaluated using four modalities: a xenograft alone (XENO; n = 6); rhBMP-2 alone (BMP; n = 6); a technique with rhBMP-2 close to the host bone covered by xenograft (SAN; n = 6); and a technique with rhBMP-2 close to the flap on top of the xenograft (LAS; n = 6). After 8 weeks, a series of in vivo inspections, fluorescence microscopy, histologic and histomorphometric evaluations, and micro-CT analyses. RESULTS: After 8 weeks of healing, new bone formation correlated with proximity of rhBMP to the perforated membrane with BMP and LAS (p = 0.024). The highest total bone volume was found in the LAS group (45.1% +/- 13.3%), followed by the SAN group (35.2% +/- 6.7%), BMP group (33.1% +/- 11.8%), followed by the XENO group (23.1% +/- 6.5%). The SAN group demonstrated frequent seroma formation. Blood vessel formation was more pronounced in the LAS + rhBMP group, with a significant increase of 27.1% compared to the XENO group (p = 0.02). Micro-CT revealed a strong trend for higher bone volume in the BMP group (34.7%) compared to the XENO group (13.6%) (p = 0.06). Only rhBMP-2 groups demonstrated bone formation above the perforated membrane. CONCLUSION: The location of rhBMP-2 in relation to the biomaterial and periosteum influenced the effectiveness of vertical bone regeneration.