Deproteinated bovine bone vs. beta-tricalcium phosphate as bone graft substitutes: histomorphometric longitudinal study in the rabbit cranial vault
This article aims to study differences in the bone formation and the graft resorption of two bone graft substitutes (BGS). Besides, it is our attempt to observe possible qualitative and quantitative differences in the bone reparation of the outer layer covered by collagen membrane and the uncovered inner layer in close contact with dura mater.
Material and methods
Twelve rabbits were employed. Deproteinized bovine bone (DBB) and β-tricalcium phosphate (BTCP) were used as BGS. Four subcritical round defects (7 mm) were drilled in the cranial vault, removing both cortical walls. One of the holes was filled with DBB, and other was filled with BTCP. Each symmetrical position to DBB and BTCP was left empty. The whole defect set was covered with a collagen membrane. Histological and morphometric analysis was performed for 1, 4, 8, 16, 32 and 52 weeks. Morphometry measurements were carried out taking into account the whole defect and splitting inner and outer areas.
In DBB sites, a rapid bone growth is observed, linking the remaining particles and integrating them into the bone matrix. Permanence of these DBB particles from week 16 onwards restrains the growth of bone fraction. A greater bone growth appears in areas repaired with BTCP than in those repaired with DBB, both in the outer layer (under-membrane) and the inner layer (over dura mater). In DBB sites, a slower growth is observed in the inner layer, with no significant differences in the final bone fraction at both strata.
Both materials favour the closure of the defects provoked. In both cases, a synergistic effect with the collagen membrane is observed. DBB remains integrated in the bone matrix, while BTCP displays a pattern of highly developed progressive resorption with an outstanding bone fraction development.