Effect of two bioabsorbable barrier membranes on bone regeneration of standardized defects in calvarial bone: A comparative histomorphometric study in pigs

Abstract

Background: The effect of two different bioabsorbable collagen membranes on bone regeneration was assessed in standardized, membraneprotected calvarial defects in pigs. Methods: Two standardized defect types (6 × 6 × 6 mm and 9 × 9 × 9 mm) were produced inthe calvaria of pigs: empty defects without a membrane (group 1; eight defects per size); defects filled with deproteinized bovine bone mineral(DBBM) withouta membrane (group2;eight defects per size); defects filled with DBBM and covered by a collagen membrane (group 3; eight defects per size); and defects filled with DBBM and covered by a cross-linked collagen membrane (CCM) (group 4; eight defects per size). Sacrifice took place 16 weeks after surgery, and the following parameters were analyzed: descriptive histology; semiquantitativehistology (SQH), assessing bone regeneration in the whole defect area; and histomorphometric analysis of the percentage of bone and DBBM in the regenerated area at three different depth levels of the defect. Results: Using SQH, both membrane types resulted in significantly better bone regeneration compared to groups 1 and 2, irrespective of the defect size (P <0.005), with no difference between the two membranes. In the histomorphometric analysis, the layer immediately below the surface exhibited a significantly higher percentage of bone in groups 3 (27%) and 4 (36%) versus the two other groups for the 9 × 9 × 9-mm defects. No such differences were apparent for the 6 × 6 × 6-mm defects or the other two depth levels (bottom and middle layer) for either defect size. Conclusions: The two collagen membranes tested significantly enhanced bone regeneration, especially in the superficial level of the calvarial bone defects. The prototype CCM did not provide any further advantage in the present animal model.