Amnion and Chorion Membranes for Root Coverage Procedures: An In Vitro Evaluation of its Physical Characteristics

Abstract

Chorion and amnion membranes are used as cost effective, allogenic substitute for the connective tissue autograft for achieving predictable root coverage. The objective of the study was to investigate the potential of amnion and chorion membranes as a substitute for the free connective tissue autograft in the bilaminar technique of root coverage. An in vitro mechanical testing and evaluation of the degradation profile of these membranes were carried out. Tensile strength, Young's modulus and elongation at break for amnion and chorion membranes were tested using universal testing machine. Suture retention and degradation tests were conducted. The tensile strength of amnion membrane is 155 kPa and that of chorion is 95 kPa. Young's Modulus of amnion membrane is 645 kPa and that of chorion is 335 kPa. Extension at break is 17.3 mm for amnion and 13.5 mm for chorion. The degradation profiles were expressed as mean accumulated weight losses of the membranes at the end of the first, second, third and fourth week. Chorion membrane has greater thickness and density when compared to amnion. Mechanical testing of these membranes points out that they are elastic in nature. Amnion is more elastic with higher tensile strength, Young's modulus and extension at break than chorion. In the suture retention test, amnion membrane can take up more load during suturing. In vitro degradation profiles of both membranes look promising. Amnion and chorion membranes are not totally degraded at the end of 4 weeks. In terms of in vitro degradation, amnion membranes appear to be more resistant than chorion membranes. Both membranes retain their physical form up to three weeks.