Graft Application and Dexamethasone Treatment Influences New Bone Formation in Rat Tibial Bone Defects

Abstract

The objective of this study were bone defect complications that occur due to traumas or infections. Bone grafts are required to provide support, fill gaps and improve biological repair in skeletal damage. Dexamethasone plays role in calcium signaling modulation and used in diseases. Aim of this study was to evaluate osteonectin and osteopontin expressions in new bone development after dexamethasone application on tibial bone defects. Rats were divided into defect, defect+graft and defect+graft+dexamethasone treated groups. Tibial bone defect created, and rats were kept immobile for 28 days. Alloplastic material was placed in defect area in second and group third groups. 2.5 mg/kg Dex and normal saline were injected to dexamethasone and defect groups twice a week for 56 days. Inflammation and congestion were increased in defect and defect+graft groups. Defect+graft+dexamethasone group; increased number of osteoblast and osteocyte cells, dense bone matrix, formation of new bone trabeculae was observed. Defect+graft group; osteonectin expression in graft regions, osteoblast cells, some connective tissue cells and fibers were seen whereas in defect+graft+dexamethasone group; osteopontin expression in osteoblast and osteocyte cells of new bone trabeculae were observed. Dexamethasone may lead to formation of new bone trabeculae into the graft material resulting in increased osteoconduction and osteoinductive effect for differentiation of osteon.