Origins and Purpose of Barrier Membranes
- First membranes were nonresorbable and required a second surgery for removal
- Development of resorbable membranes to avoid the need for second surgery
- No statistically significant difference in surgical success between nonresorbable and resorbable membranes
- Membrane prohibits penetration of cells, primarily epithelial, to separate bone defect from soft tissue
- Allows time for bone cells to fill the defect and prevent occupation by soft tissue cells
- Soft tissue flap must survive on vascular supply and cannot rely on granulation tissue from underlying bone

Types of Barrier Membranes
- Barrier membranes derived from natural and synthetic sources
- Marketed under various trade names
- Two principal varieties used in guided bone regeneration (GBR) and grafting: non-resorbable and resorbable
- Non-resorbable membranes historically included millipore (paper) filter barriers and ePTFE membranes introduced in 1984
- ePTFE membranes often contaminated with bacteria and require removal via extra surgery
- Long-term studies suggest bones regrown with ePTFE function as well as non-augmented bone
- Resorbable membranes can be either animal-derived or synthetic polymers
- Sources include rat or cow collagen, polylactic acid, polyglycolide, Vicryl, artificial skin, and freeze-dried dura mater
- Synthetic resorbable membranes may be polymers of lactic acid or glycolic acid

Clinical Considerations of Barrier Membranes
- Superficial soft tissue flap remains separated from underlying bone during primary healing period
- Two types of bony defects: space-making and non-space-making
- Space-making defects are less demanding than non-space-making defects

Research Studies on Barrier Membranes in Guided Bone Regeneration
- Simion M, Scarano A, Gionso L, Piattelli A (1996) conducted a comparative histologic study on guided bone regeneration using resorbable and nonresorbable membranes in humans.
- Simion M, Misitano U, Gionso L, Salvato A (1997) conducted a comparative clinical study on the treatment of dehiscences and fenestrations around dental implants using resorbable and nonresorbable membranes associated with bone autografts.
- Hämmerle CH, Lang NP (2001) published a study on single stage surgery combining transmucosal implant placement with guided bone regeneration and bioresorbable materials.
- Stavropoulos F, Dahlin C, Ruskin JD, Johansson C (2004) conducted an experimental study on barrier membranes as graft protectors in the treatment of localised bone defects in a canine model.
- Hämmerle CH, Jung RE, Yaman D, Lang NP (2008) reported on ridge augmentation using bioresorbable membranes and deproteinised bovine bone mineral in twelve consecutive cases.

Augmentation Procedures for Deficient Edentulous Ridges with Oral Implants
- Chiapasco M, Zaniboni M, Boisco M (2006) discussed augmentation procedures for the rehabilitation of deficient edentulous ridges with oral implants.
- Ridge augmentation is a common procedure for improving bone volume in edentulous ridges.
- Oral implants can be used to restore missing teeth in deficient edentulous ridges.
- Augmentation procedures involve the use of barrier membranes and bone grafts to enhance bone regeneration.
- Successful ridge augmentation can improve esthetics and provide support for dental prostheses.