Overaugmentation to compensate for postextraction ridge atrophy using a putty-type porcine bone substitute material with recombinant bone morphogenetic protein-2: 4 weeks of healing in a canine model

Objectives: The aims of the present study were (i) to determine the short-term effects of putty-type porcine bone substitute material (PB) with recombinant bone morphogenetic protein-2 (rhBMP-2) for alveolar ridge preservation (ARP) and (ii) evaluate the early healing of labial overaugmentation. Materials and methods: Two groups were randomly assigned to the extraction sockets in mandibular incisors of eight dogs: labial overaugmentation with (i) PB (control) or (ii) rhBMP-2-loaded PB (BMP). Microcomputed tomography (micro-CT), and histologic and histomorphometric analyses were performed after 4 weeks. Results: Micro-CT revealed that some of the overaugmented PB was dispersed in both groups. The new bone volume was significantly larger in the BMP group than in the control group (18.4 ± 3.3 vs. 15.5 ± 3.0 mm ³ , mean ± SD, P < 0.05). Labial bone resorption was generally found histologically. No signs of mineralization were observed in the overaugmented area despite significantly increased ridge width, as compared to the adjacent tooth area. The area of new bone formation was larger in the BMP group than in the control group overall (23.7 ± 18.8 vs. 18.3 ± 21.2 mm ² ) and in three parts (apical, middle, and coronal), although the difference was statistically significant only in the coronal part (7.7 ± 7.9 vs. 4.6 ± 6.4 mm ² , P < 0.05). Conclusions: The addition of rhBMP-2 enhanced ossification in the coronal part of the extraction socket relative to using PB alone. Overaugmentation increased the ridge dimension with no evidence of ossification in situ at 4 weeks. Clinical relevance: In early healing following ARP, rhBMP-2 enhances bone formation within the socket, but ossification in the overaugmented area needs to be studied further.