**8. Cytological changes that occurred through two mechanisms in the bones either distraction of bone or grafting bone defect by iliac crest bone graft and the role of mesenchymal stem cells**

Our recent advances in bone research by experimental studies are by using rabbits as animal models for studding distraction technique for elongation of bones and studying the changes of bone grafting and the cellular changes associated and the role of mesenchymal stem cells.

Bone grafting is also another interesting topic. We did research on rabbits [16] by resecting a piece of bone of 1.5 cm from the lower border of rabbit mandible and reconstructed by a piece of bone from the iliac crest of the rabbit of about 2 cm after decortication of both segments of the mandible and fixed by rigid fixation by stainless steel soft wire of 0.25 mm. The rabbits were divided for purpose of experiment into two groups: one bone graft was fixed without a cover by oxidized regenerating cellulose (Surgicel) in group A, and in the second group, group B, the graft was covered by oxidized regenerating cellulose mesh (Surgicel), to study the cytological changes associated with bone grafting and the differences between two groups

Introductory Chapter: Bone Grafting and Its Application in Cranial-Maxillofacial Surgery…

http://dx.doi.org/10.5772/intechopen.80299

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The aim was to study the role of mesenchymal stem cells in bone grafting. In the experiment, 12 young rabbits of 3 months of age were divided into two groups, group A and group B, each group of five rabbits and two rabbits used as control. These rabbits were subjected to surgical osteotomy by excising 1.5 cm from the body of the mandible, and bone graft of 2 cm length was harvested from the iliac crest of the rabbit and fixed by rigid fixation by soft stainless steel wire of 0.25 mm. Oxidized regenerated cellulose (Surgicel) was used as mesh to cover the bone graft of group B; 3 months later, the experiment was terminated. The histologi-

Histological and cytological changes of bone grafting was quiet interesting and showed formation of clot and platelet aggregation with releasing growth factor (PGF), and healthy granulation tissue was formed with mesenchymal stem cells derived from the bone marrow, periosteum, and covering muscles with formation of a large amount of fibroblasts and tiny small vessels. Osteoblasts were seen with the chondrocyte; these changes were noticed more with bone graft that was covered by Surgicel in group B. The role of Surgicel was to accelerate

This research proved to be of great value to humans for better understanding of the cellular changes and the mechanisms associated with bone grafting and distraction for elongation of bones in children. The cellular changes of distraction technique and bone grafting by inducing mesenchymal stem cells are the same except distraction induced by stretching growth potential of bones based on Illizarov theory, and the bone grafting based on maximum contact between bone graft and bony segments after decortication of the segments with rigid fixation

The management of bony defect urgently required bone grafting after traumatic injuries, after

of rabbits in healing process and cytological status.

the healing process of bone grafting.

**Author details**

Raja Kummoona

cal sections were obtained every 2 weeks, 4 weeks, and 8 weeks.

can be achieved by plating or by soft stainless steel wire of 0.25 mm.

Address all correspondence to: raja\_kummoona@hotmail.com

Iraqi Board for Medical Specialization's, Medical City, Baghdad, Iraq

missile war injuries, and after radical cancer surgery as an urgent technique.

Distraction is defined as the process of generating new bone by stretching distraction osteogenesis (DO). Traction on the living tissue can stimulate and maintain regeneration and growth by stimulating the proliferation of precursor cells.

The human body has an enormous regenerative ability to induce a regenerative ability and distraction osteogenesis (DO) which takes the advantages of this regenerative ability to induce the regeneration and remodeling of bone [13, 14].

We did experimental studies on rabbits by achieving distraction of the mandible [15] to demonstrate that the previous literature did not mention about the biological changes that occur in the gap created by osteotomy of the bone site desired during the latent period which is the key factor in distraction process and formation of new bone.

The mechanisms of surgical distraction technique are passed through three phases—phase one is the surgical phase, phase two is the latent period phase, and the third phase is the consolidation phase. Surgical phase is started by fitting distraction apparatus and gap creation by osteotomy. The second phase is the phase of the latent period where the biological and cellular changes occurred by formation of clot and granulation tissue with the release of growth factor (GF) from platelets with proliferation of mesenchymal stem cells derived from bone marrow, periosteum, and covering muscles with active fibroblast formation under the influence and action of growth factor (GF); this phase is the silent phase elapsed between 7 and 10 days.

Distraction of the lower jaw was achieved by using bilateral distractor designed for hand bone lengthening apparatus which was adjusted by transfixation by Kirschner wire of 1.5 mm which was passed through both mandibular bodies. Rhythmic distraction of both corticomized fragments was carried out at a rate of 1 mm/day at a rhythm of 0.5 mm twice daily for 10 days. The segments hold for 6 weeks till consolidation phase is completed, and bone formation and regeneration were evaluated radiologically.

Bone regeneration by distraction is a highly complicated and organized process. Through our research, we found in the histological studies revealed and demonstrated by our experiment that bone regeneration is based on membranous ossification preceded by formation of granulation tissue and mesenchymal stem cells derived from bone marrow of bone segments and periosteum lining and covering muscles with formation of active fibroblasts in the same direction of stretching forces by the influence of growth factor (GF) for formation of new bone, muscles, and even skin [13–15].

Bone grafting is also another interesting topic. We did research on rabbits [16] by resecting a piece of bone of 1.5 cm from the lower border of rabbit mandible and reconstructed by a piece of bone from the iliac crest of the rabbit of about 2 cm after decortication of both segments of the mandible and fixed by rigid fixation by stainless steel soft wire of 0.25 mm. The rabbits were divided for purpose of experiment into two groups: one bone graft was fixed without a cover by oxidized regenerating cellulose (Surgicel) in group A, and in the second group, group B, the graft was covered by oxidized regenerating cellulose mesh (Surgicel), to study the cytological changes associated with bone grafting and the differences between two groups of rabbits in healing process and cytological status.

The aim was to study the role of mesenchymal stem cells in bone grafting. In the experiment, 12 young rabbits of 3 months of age were divided into two groups, group A and group B, each group of five rabbits and two rabbits used as control. These rabbits were subjected to surgical osteotomy by excising 1.5 cm from the body of the mandible, and bone graft of 2 cm length was harvested from the iliac crest of the rabbit and fixed by rigid fixation by soft stainless steel wire of 0.25 mm. Oxidized regenerated cellulose (Surgicel) was used as mesh to cover the bone graft of group B; 3 months later, the experiment was terminated. The histological sections were obtained every 2 weeks, 4 weeks, and 8 weeks.

Histological and cytological changes of bone grafting was quiet interesting and showed formation of clot and platelet aggregation with releasing growth factor (PGF), and healthy granulation tissue was formed with mesenchymal stem cells derived from the bone marrow, periosteum, and covering muscles with formation of a large amount of fibroblasts and tiny small vessels. Osteoblasts were seen with the chondrocyte; these changes were noticed more with bone graft that was covered by Surgicel in group B. The role of Surgicel was to accelerate the healing process of bone grafting.

This research proved to be of great value to humans for better understanding of the cellular changes and the mechanisms associated with bone grafting and distraction for elongation of bones in children. The cellular changes of distraction technique and bone grafting by inducing mesenchymal stem cells are the same except distraction induced by stretching growth potential of bones based on Illizarov theory, and the bone grafting based on maximum contact between bone graft and bony segments after decortication of the segments with rigid fixation can be achieved by plating or by soft stainless steel wire of 0.25 mm.

The management of bony defect urgently required bone grafting after traumatic injuries, after missile war injuries, and after radical cancer surgery as an urgent technique.
