Injectable, compression-resistant polymer/ceramic composite bone grafts promote lateral ridge augmentation without protective mesh in a canine model.

OBJECTIVE: The objective of this study was to test the hypothesis that a compression-resistant bone graft augmented with recombinant human morphogenetic protein-2 (rhBMP-2) will promote lateral ridge augmentation without the use of protective mesh in a canine model. MATERIALS & METHODS: Compression-resistant (CR) bone grafts were evaluated in a canine model of lateral ridge augmentation. Bilateral, right trapezoidal prism-shaped defects (13-14 mm long x 8-9 mm wide x 3-4 mm deep at the base) in 13 hounds (two defects per hound) were treated with one of four groups: (i) absorbable collagen sponge + 400 mug rhBMP-2/ml (ACS, clinical control) protected by titanium mesh, (ii) CR without rhBMP-2 (CR, negative control), (iii) CR + 200 mug rhBMP-2 (CR-L), or (iv) CR + 400 mug rhBMP-2 (CR-H). All animals were euthanized after 16 weeks. Ridge height and width and new bone formation were assessed by muCT, histology, and histomorphometry. The release kinetics of rhBMP-2 from CR bone grafts in vitro and in vivo in a femoral condyle defect model in rabbits was also evaluated. RESULTS: All four bone grafts promoted new bone formation (11-31.6 volume%) in the lateral ridge defects. For CR grafts, ridge height and width increased in a dose-responsive manner with increasing rhBMP-2 concentration. Ridge height and width measured for CR-H without the use of protective mesh was comparable to that measured for ACS with a protective mesh. CONCLUSIONS: At the same dose of rhBMP-2, an injectable, compression-resistant bone graft resulted in a comparable volume of new bone formation with the clinical control (ACS). These findings highlight the potential of compression-resistant bone grafts without the use of protective mesh for lateral ridge augmentation.