Higher solubility and lower onset temperature of protein denaturation increase the osteoconductive capacity of collagen membranes: A preclinical in vivo study

Objectives

Collagen membranes are extensively used for guided bone regeneration procedures, primarily for horizontal bone augmentation. More recently, it has been demonstrated that collagen membranes promote bone regeneration. Present study aimed at assessing if structural modifications of collagen membranes may enhance their osteoconductive capacity.

Methods

Twenty-four adult Wistar rats were used. Bilateral calvaria defects with a diameter of 5 mm were prepared and covered with prototypes of collagen membranes (P1 or P2). The P1 membrane (positive control) presented a lower onset temperature of protein denaturation and a higher solubility than the P2 membrane (test). The contralateral defects were left uncovered (NC). After 1 and 4 weeks, the animals were euthanized. A microcomputed tomography analysis of the harvested samples was performed within and above the bony defect. Undecalcified ground sections were subjected to light microscopy and morphometric analysis.

Results

Bone formation was observed starting from the circumferential borders of the defects in all groups at 1-week of healing. The foci of ossification were observed at the periosteal and dura mater sites, with signs of collagen membrane mineralization. However, there was no statistically significant difference between the groups. At 4 weeks, remnants of the collagen fibers were embedded in the newly formed bone. In the P2 group, significantly more bone volume, more new bone, and marrow spaces compared to the NC group were observed. Furthermore, the P2 group showed more bone volume ectocranially then the P1 group.

Conclusions

Bone formation subjacent to a P2 membrane was superior than subjacent to the P1 membrane and significantly better compared to the control. Modifications of the physico-chemical properties may enhance the osteoconductive competence of collagen membranes, supporting bone formation outside the bony defects.