Mechanical stability of collagen membranes: an in vitro study
Objectives: For large horizontal augmentations or cases requiring even a minor vertical augmentation there is a clinical need for mechanically stable resorbable membranes that can be fixated with pins to immobilize the graft material. An investigation of native non-chemically cross-linked collagen membranes focusing on differences in degradation behavior and tissue integration has indicated good mechanical properties of a newly developed collagen membrane (CX). The aim of this study was to compare the mechanical strength of commonly used native non-chemically cross-linked [NXL] and chemically cross-linked [XL] collagen membranes in-vitro.
Methods: Five NXL* and five XL§ membranes were included (n=6 samples each) and immersed in saline at room temperature until fully hydrated. Force at break (N), stress at break (N/mm2) and suture retention (N) were tested in-vitro using a Zwick/Roell Z2.5 tensile tester (Ulm, Germany). Statistical analysis of in vitro test results was performed using Wilcoxon test with Bonferroni corrections for multiple comparisons. CX was the comparison group for all statistical tests. Significance was set at (P< 0.05).
Results: The highest median force at break 21.2 N (IQR: 13-23.7), stress at break 14.2 N/mm2 (IQR: 9.1-16.3) and suture retention 6.1 N (IQR: 5.9-6.5) was measured for CX. Results were significant compared with BG, JS, OF and BM, CY & OP membranes for force and stress at wet break (Table). Suture retention reached significance compared to all but one membrane. No trends in the mechanical strength performance across the two groups, NXL and XL, were observed.
Conclusions: After wetting the CX membrane has higher mechanical strength, resists higher stress and has higher pull out force than all other included NXL and XL collagen membranes. The CX membrane provides high strength required for use as a barrier membrane for GBR procedures to treat large defects such as horizontal ridge augmentation.