Efficacy of Collagenous Sponge for Bone Regeneration in Mandibular Defects in the Absence of Periosteum of Adult Rabbits

Abstract

The efficacy of absorbable collagenous sponge for bone regeneration was evaluated in critical size mandibular bone defects in the absence of periosteum, focusing on the healing process between the cortical cut-ends. Eighteen white Japanese rabbits were operated on to create a uni-cortical bone defect (12×9×3.5 mm) without periosteum in the right mandible. The defects were filled with collagenous sponges or left empty (unfilled). At 2, 4 and 8 weeks after the operation, the mandibles were removed and coronal sections were stained with hematoxylin-eosin for histological observation and morphometric analysis.
In the collagenous sponge group, mesenchymal cells proliferated in the highly porous matrix at 2 weeks, and a trabecular bone bridge was found between the cortical cut-ends at 4 weeks. The collagen-filled defects achieved complete bony bridge formation by 8 weeks,whereas the unfilled defects were interposed by soft tissues. Histomorphometric analysis of the area between cortical cut-ends at 4 weeks demonstrated that the bone tissue occupied 93.9% of the volume in the collagenous sponge group compared to 9.3% in the unfilled group.The volume of the collagenous sponge was 11.5% and 0%, at 2 and 4 weeks, respectively.
Our present results indicate that the collagenous matrix provides a space for the proliferation and differentiation of mesenchymal cells and contributes to the mandibular contour formation by bony bridging. The collagenous sponge may be effective in promoting regeneration of bone defects in the absence of periosteum by acting as a scaffold and eventually being absorbed and replaced by new bone.