Evaluation of Vertical Bone Regeneration Using Block and Particulate Forms of Bio-Oss Bone Graft: A Histologic Study in the Rabbit Mandible
The aim of the present study was to evaluate histologically vertical bone regeneration outcomes after using bovine bone graft material in block and granular forms. The buccal bony plates of the outer mandibles of 10 New Zealand rabbits received Bio-Oss blocks that were immobilized using orthopedic mini-plates, and another 10 received granular forms that were gently packed and stabilized into the custom-made perforated metallic cubes. The mean graft area (GA), new bone area (NBA), bone-to-graft contact (BGC), and maximum vertical height reached by the new bone development (MVH) were histometrically evaluated and showed no significant differences between 2 graft types. The new bone was observed mostly close to the basal bone and developed penetrating the trabecular scaffold in the form of seams that covered the intralumen surfaces of the block type graft, while in the granular graft type the new bone was observed to grow between the graft particles usually interconnecting them. Either form of Bio-Oss was capable of providing considerable vertical bone augmentation.
Figure 1. (a) The block-form bone graft was placed in direct contact with the bone surface and was immobilized using Π-shaped orthopedic mini-plates and bone screws. (b) The particulate-form bone graft was in the custom-made perforated metallic cubes secured with bone screws. Figure 2. Histologic samples of group A. General view of the new bone regeneration. It was derived from the basal native bone (a) and encountered mostly close to the basal bone as well as in the middle of the augmentation area (b) in the form of flowing patterns of new bone covering the walls of the lumens within the scaffold of Bio-Oss block. (Original magnification ×10 and stained with Sanderson's rapid bone stain [RBS].) Figure 3. (a) In this magnification of rectangle A in Figure 2a, new bone derived from the basal native bone and extending coronally within the framework of the block graft can be seen. (b) Magnification of the rectangle in Figure 2b. The current view is located in the middle region. New woven bone can be seen in close contact with the intra-lumen spaces of the Bio-Oss scaffold. (Original magnification ×40 and stained with Sanderson's RBS.)
Figure 4. Histologic samples of group B, which used the granular form of Bio-Oss bone graft. New bone was developed as rods and plates among the interspersed graft particles. (Original magnification ×10. Trichrome stain on the left and Sanderson's rapid bone stain [RBS] on the right.) Figure 5. (a) Magnification of group B samples. This magnification of the rectangle in the middle region of Figure 4b reveals new bone growth interconnecting the graft particles. Osteoblast layers in high activity were developed around the new bone bridges (black arrows). Osteoid apposition can be seen as reddish layers in contact either with the newly formed bone or directly with the graft material. (Original magnification ×40, trichrome stain left.) (b) Slender spongiosa with large size osteocytes characterize woven bone in the early maturation stage. (Original magnification ×40, Sanderson's RBS.) Figure 6. (a) In histologic samples from group A (block form bone graft), a “bridging” effect of the new bone growth could be seen within the graft trabeculae. A clear bridge consisting of composite new bone was developed interconnecting 2 proximal edges of the graft scaffold. (b) Woven bone with numerous large size osteocytes in early development stage can be seen among proximal graft trabeculae. (Original magnification ×40, stained with Sanderson's RBS.)
Magnification of rectangle C in the coronal region of Figure 2a. A rare observation of new bone growth at the coronal region of a block form graft consisting of composite bone (ie, areas of lamellar and woven bone in close contact with the trabeculae walls of the block graft framework). (Original magnification ×40, stained with Sanderson's rapid bone stain.)
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