Correlation in the densities of augmented and existing bone in guided bone augmentation

Our previous work used a rabbit experimental model to investigate the effectiveness of guided bone augmentation (GBA). Although a density similar to that of existing bone is required for successful bone augmentation, few studies have compared the densities of augmented and existing bone. The purpose of the present study was to investigate the correlation in the densities of existing and augmented bone following GBA in rabbit calvaria.

The calvaria of 18 adult male Japanese white rabbits were exposed. A circular groove and nine small holes were drilled into the cortical surface of each left parietal bone. A customized, standardized, hemispherical titanium cap was press-fitted into each groove. Six animals were sacrificed after each healing period of 1, 3, and 6 months and histomorphometric analyses were conducted.

Significant increases were observed in the area of augmented bone between 1 and 6 months (62.7 ± 21.6% vs. 93.4 ± 3.9%). In contrast, no significant differences among healing periods were observed in the density of augmented or existing bone. Regression analysis demonstrated a significant positive correlation between the densities of augmented and existing bone; the strength of this correlation increased with the length of healing (R(2) =0.97).

These results suggest that the area of augmented bone increases significantly with the length of healing, filling the occlusive space after 6 months, and that the density of augmented bone depends on that of the existing bone, such that augmented bone has a density about half that of the existing bone.