Superficial Topography and Porosity of an Absorbable Barrier Membrane Impacts Soft Tissue Response in Guided Bone Regeneration

Abstract

Surface topography and porosity of barrier membranes is suggested to impact the soft and hard tissue response. In this study, the specific soft and hard tissue response characteristics of a synthetic polylactide membrane are evaluated including soft tissue inflammation, osteogenesis, and osteopromotion. Analysis of porosity and surface topography of the test material was performed by scanning electron microscopy. Transosseous parietal defects were surgically created bilaterally in 32 BalbC/ByJ mice and treated either with the barrier (test) or sham-operated (control). Healing was assessed histologically and histomorphometrically with quantification of bone bridging. Scanning electron microscopy analyses of the barrier revealed a microstructure resembling cancellous bone. Interconnecting pores and channels, measuring between 6 and 60 microm in diameter, formed by smooth internal walls were observed throughout the device. Two distinct patterns of porosity were observed. The external surface of the membrane was characterized by a highly porous structure, with minimal interporous nodes and average pore sizes ranging between 6 and 20 microm in diameter. The internal surface was characterized by a minimal porous structure, with significant interporous nodes and average pore sizes ranging between 18 and 60 mum in diameter. Histomorphometric analyses demonstrated increased bone bridging by 60% and 300% in membrane-treated sites after 14 and 28 days of healing, respectively. The rough surface of the barrier contained significantly more giant cells, whereas the smooth surface contained significantly more inflammatory cells. The surface topographies engineered on different sides of the barrier promote differential soft tissue responses leading, however, to similar amounts of enhanced bone formation.