Barrier membrane
Encyclopedia
A barrier membrane is a device used in oral surgery and periodontal surgery
to prevent epithelium
, which regenerates relatively quickly, from growing into an area in which another, more slowly-growing tissue type, such as bone
, is desired. Such a method of preventing epithelial migration into a specific area is known as guided tissue regeneration (GTR).
derived from the underlying bone.
Two types of bony defects exist that may require the use of a membrane:
Space-making defects, such as extraction sockets with intact bony walls, are not as demanding as non-space-making defects, such as sites of ridge augmentation, where there may be no support for the membrane and the soft tissue cover may cause collapse of the membrane during healing.
(GBR) and grafting may be of two principal varieties:
(ePTFE) membranes were first used by in 1984, being non-resorbable, but compatible with humans and not leading to infection. Although ePTFE are considered the standard for membranes and excellent outcomes have been achieved with this material, they are often contaminated with bacteria
(which limits the amount of bone regrowth that will occur) and must eventually be removed via at least one extra surgery 4–6 weeks after the tissue has regrown. Resorbable membranes were developed to avoid these limitations. Non-absorbable ePTFE membranes are still used clinically on a regular basis, and long-term studies suggest that bones regrown with ePTFE function as well as non-augmented naive bone.
, cargile membrane
, polylactic acid
, polyglycolide
, Vicryl
, artificial skin
and freeze-dried dura mater
. Recently developed synthetic membranes often combine different materials.
, promote the attachment of new connective tissue
, are not strongly antigen
ic and prevent blood loss
by promoting platelet
aggregation leading to early clot formation and wound stabilization. Collagen membranes may also facilitate primary wound closure via fibroblast chemotactic properties, even after membrane exposure. Compared to ePTFE membranes, resorbable barriers allow for fewer exposures and therefore reduce the effects of infection on newly formed bone. Use of collagen membranes in particular, with bone mineral as a support and space maintainer, has achieved predictable treatment outcomes.
or glycolic acid
. Their ester
bonds are degraded over 30–60 days, leaving free acids that may be inflammatory
. The majority of studies consider synthetics comparable to other membranes like ePTFE and collagen, and one author has found synthetics clinically superior to collagen membranes.
The integrity of resorbable membranes over the healing period has been questioned relative to the ePTFE membranes, but a 2007 study suggested that collagen membranes do allow for bone regeneration, given the correct patient and conditions. Most studies on resorbable membranes do not use appropriate scientific control
s or identify the specific membrane used, making it difficult to compare success and failure rates.
Petti G. (1988) “A new attachment:guided tissue regeneration using an amniotic membrane and fibrin glue-preclinical considerations after 2 years” The Journal of the American Dental Association, JADA/FDI. Free Communications, Periodontics, July, USA
Petti G. (1988) “ A new attachment:guided tissue regeneration using an amniotic membrane and fibrin glue” Dental Abstract, USA
See in The References the others numerous publications
Oral Surgery
Oral Surgery is a recognized international specialty in dentistry. It includes the diagnosis, surgical and related treatment of diseases, injuries and defects involving both the functional and esthetic aspects of the hard and soft tissues of the head, mouth, teeth, gums, jaws and neck.It involves,...
to prevent epithelium
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
, which regenerates relatively quickly, from growing into an area in which another, more slowly-growing tissue type, such as bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
, is desired. Such a method of preventing epithelial migration into a specific area is known as guided tissue regeneration (GTR).
Origins
The first membranes developed were nonresorbable and required a second surgery for membrane removal some weeks later. The need for a second surgical procedure hindered the utilization of the original barrier membranes, which led to the development of resorbable membranes; research indicates no statistically significant difference in surgical success between the two types.Purpose
The purpose of a membrane is to prohibit the penetration of cells, primarily epithelial, through its structure.Clinical considerations
When barrier membranes are utilized, the superficial soft tissue flap remains separated from the underlying bone for the primary healing period and must survive on the vascular supply of the flap; it cannot rely on granulation tissueGranulation tissue
Granulation tissue is the perfused, fibrous connective tissue that replaces a fibrin clot in healing wounds. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size it heals...
derived from the underlying bone.
Two types of bony defects exist that may require the use of a membrane:
- Space-making defect
- Non-space-making defect
Space-making defects, such as extraction sockets with intact bony walls, are not as demanding as non-space-making defects, such as sites of ridge augmentation, where there may be no support for the membrane and the soft tissue cover may cause collapse of the membrane during healing.
Types
Barrier membranes have been derived from a variety of sources, both natural and synthetic, and are marketed under various trade names. Membranes used in guided bone regenerationGuided bone regeneration
Guided bone regeneration or GBR, and guided tissue regeneration or GTR are dental surgical procedures that utilize barrier membranes to direct the growth of new bone and gingival tissue at sites having insufficient volumes or dimensions of bone or gingiva for proper function, esthetics or...
(GBR) and grafting may be of two principal varieties:
- non-resorbable
- resorbable.
Non-resorbable
Historically, GBR and grafting techniques began with impractical millipore (paper) filter barriers. Expanded polytetrafluoroethylenePolytetrafluoroethylene
Polytetrafluoroethylene is a synthetic fluoropolymer of tetrafluoroethylene that finds numerous applications. PTFE is most well known by the DuPont brand name Teflon....
(ePTFE) membranes were first used by in 1984, being non-resorbable, but compatible with humans and not leading to infection. Although ePTFE are considered the standard for membranes and excellent outcomes have been achieved with this material, they are often contaminated with bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
(which limits the amount of bone regrowth that will occur) and must eventually be removed via at least one extra surgery 4–6 weeks after the tissue has regrown. Resorbable membranes were developed to avoid these limitations. Non-absorbable ePTFE membranes are still used clinically on a regular basis, and long-term studies suggest that bones regrown with ePTFE function as well as non-augmented naive bone.
Resorbable
Resorbable membranes are either animal-derived or synthetic polymers. They are gradually hydrolyzed or enzymatically degraded and therefore do not require a second surgical stage of membrane removal. Their sources are varied, beginning in early years with rat or cow collagenCollagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
, cargile membrane
Cargile membrane
A Cargile membrane was a sterile membrane prepared from the peritoneum of the ox, and used in abdominal surgery to interpose between raw surfaces and thus prevent the formation of adhesions...
, polylactic acid
Polylactic acid
Poly or polylactide is a thermoplastic aliphatic polyester derived from renewable resources, such as corn starch , tapioca products or sugarcanes...
, polyglycolide
Polyglycolide
Polyglycolide or Polyglycolic acid is a biodegradable, thermoplastic polymer and the simplest linear, aliphatic polyester. It can be prepared starting from glycolic acid by means of polycondensation or ring-opening polymerization. PGA has been known since 1954 as a tough fiber-forming polymer...
, Vicryl
Vicryl
Vicryl is an absorbable, synthetic, braided suture, manufactured by Ethicon Inc., a subsidiary of Johnson and Johnson. It is indicated for soft tissue approximation and ligation. The suture holds its tensile strength for approximately three to four weeks in tissue, and is completely absorbed by...
, artificial skin
Artificial skin
Artificial skin can refer to skin grown in a laboratory that can be used as skin replacement for people who have suffered skin trauma such as severe burns or skin diseases.Alternatively, it can also refer to skin synthetically produced for other purposes....
and freeze-dried dura mater
Dura mater
The dura mater , or dura, is the outermost of the three layers of the meninges surrounding the brain and spinal cord. It is derived from Mesoderm. The other two meningeal layers are the pia mater and the arachnoid mater. The dura surrounds the brain and the spinal cord and is responsible for...
. Recently developed synthetic membranes often combine different materials.
Collagen resorbable membranes
Collagen membranes are of either type I or II collagen from cows or pigs. They are often cross-linked and take between four and forty weeks to resorb, depending on the type. Collagen absorbable barrier membranes do not require surgical removal, inhibit migration of epithelial cellsEpithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
, promote the attachment of new connective tissue
Connective tissue
"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...
, are not strongly antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
ic and prevent blood loss
Hemostasis
Hemostasis or haemostasis is a process which causes bleeding to stop, meaning to keep blood within a damaged blood vessel . Most of the time this includes blood changing from a liquid to a solid state. Intact blood vessels are central to moderating blood's tendency to clot...
by promoting platelet
Platelet
Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is normally just 5 to 9 days...
aggregation leading to early clot formation and wound stabilization. Collagen membranes may also facilitate primary wound closure via fibroblast chemotactic properties, even after membrane exposure. Compared to ePTFE membranes, resorbable barriers allow for fewer exposures and therefore reduce the effects of infection on newly formed bone. Use of collagen membranes in particular, with bone mineral as a support and space maintainer, has achieved predictable treatment outcomes.
Synthetic resorbable membranes
Synthetic membranes may be polymers of lactic acidLactic acid
Lactic acid, also known as milk acid, is a chemical compound that plays a role in various biochemical processes and was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele. Lactic acid is a carboxylic acid with the chemical formula C3H6O3...
or glycolic acid
Glycolic acid
Glycolic acid is the smallest α-hydroxy acid . This colorless, odorless, and hygroscopic crystalline solid is highly soluble in water. It is used in various skin-care products. Glycolic acid is found in some sugar-crops...
. Their ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
bonds are degraded over 30–60 days, leaving free acids that may be inflammatory
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
. The majority of studies consider synthetics comparable to other membranes like ePTFE and collagen, and one author has found synthetics clinically superior to collagen membranes.
The integrity of resorbable membranes over the healing period has been questioned relative to the ePTFE membranes, but a 2007 study suggested that collagen membranes do allow for bone regeneration, given the correct patient and conditions. Most studies on resorbable membranes do not use appropriate scientific control
Scientific control
Scientific control allows for comparisons of concepts. It is a part of the scientific method. Scientific control is often used in discussion of natural experiments. For instance, during drug testing, scientists will try to control two groups to keep them as identical and normal as possible, then...
s or identify the specific membrane used, making it difficult to compare success and failure rates.
Amniotic membrane and fibrin glue
PETTI Gustavo From Cagliari, Italy has been the first one to have had: "A new attachment: guided tissue regeneration using an amniotic membrane and fibrin glue" Pubblication: Petti G. (1989) “La rigenerazione parodontale guidata con membrana amniotica e colla di fibrina. (Guided periodontal regeneration with an amniotic membrane and fibrin glue). Il Dentista Moderno, 9, 57-70. ItalyPetti G. (1988) “A new attachment:guided tissue regeneration using an amniotic membrane and fibrin glue-preclinical considerations after 2 years” The Journal of the American Dental Association, JADA/FDI. Free Communications, Periodontics, July, USA
Petti G. (1988) “ A new attachment:guided tissue regeneration using an amniotic membrane and fibrin glue” Dental Abstract, USA
See in The References the others numerous publications