De novo bone formation underneath the sinus membrane supported by a bone patch: a pilot experiment in rabbit sinus model.

Abstract

The objectives of this study were to evaluate bone regeneration beneath a newly devised bone substitute combined with collagen membrane (called a bone patch) lying over a concomitantly placed mini-implant following sinus floor elevation and verify its usefulness as a carrier system for recombinant human bone morphogenetic protein-2 (rhBMP-2) in rabbits. The sinus floor elevation procedure was performed bilaterally in five rabbits. Either a plain bone patch (control group) or an rhBMP-2-loaded patch (experimental group) was randomly placed beneath the elevated sinus membrane (SM) of both sinuses, where the mini-implants were concomitantly placed. Micro-computed tomographic and histologic analyses were performed at 4weeks post-surgery. In micro-computed tomography, the median values of the total augmented volume and the mineralized bone volume were significantly higher in the experimental group than in the control group (161 vs. 122mm3 [P<0.01] and 48 vs. 42mm3 [P<0.05], respectively). Histometric analysis revealed the same outcomes, with new bone areas of 6.41 and 2.97mm2 in the experimental and control groups, respectively (P<0.001), and bone-to-implant contact ratios of 22.6% and 5.2%, respectively (P<0.001). The newly devised bone patch in this study can support the elevated SM and facilitate bone regeneration from the basal bone with a reduced amount of biomaterial. The addition of rhBMP-2 may shorten the healing time for multidirectional bone regeneration toward the implant.