Bone Regeneration and Degradation Patterns of Different Collagen Materials

Objectives: Various crosslinking methods have been introduced to increase performance of collagen membrane. Aim of this study is to compare and evaluate degradation and bone regeneration pattern of three different collagen materials in rabbit calvaria model with histologic and CT analysis.

Methods: Four 8mm diameter circular bone defects were created in the calvarium of 10 rabbits. Each defect in calvarium were randomly allocated to 1) sham control, 2) non-crosslinked sponge type collagen membrane group (N), 3) chemically crosslinked collagen membrane group (CM) and 4) biphasic calcium phosphate (BCP) added ultraviolet (UV) crosslinked collagen membrane (UVM). Each defect was covered with allocated membrane without any graft material. After 2 weeks and 8 weeks, rabbits were sacrificed and experimental defects were investigated by micro-CT analysis and histologic analysis.

Results: There was no difference in new bone area and new bone volume in between experimental groups and control groups. Total tissue area of CM group in 2 weeks was significantly larger compared to other groups. In histologic analysis, CM kept its shape until 8 weeks, while UVM and N were almost fully degraded in 8 weeks. In 2 weeks, infiltration of inflammatory cell was notable in margin of CM and UVM. In 8 weeks, infiltration of inflammation was sustained in margin of CM while it was absent in UVM. Both CM and UVM showed unique new bone formation pattern in 2 weeks. In 2 weeks histologic analysis, new bone was formed along the below of the CM and UVM, while new bone was formed in the lower position of the defect in N and control group.

Conclusions: CM was maintained longer than UVM, however, in same time CM accompanied longer inflammation compared to UVM. Both CM and UVM showed its distinctive enhanced new bone formation pattern in early phase.