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 »  Home  »  Dental Implant 1  »  Collagen Membrane Resorption in Dogs: A Comparative Study
Collagen Membrane Resorption in Dogs: A Comparative Study
Introduction.

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Kris W. Owens, DDS, MS
Postgraduate Periodontics Student, Dept. of Periodontics, Louisiana State University School of Dentistry, New Orleans, LA, USA.

Raymond A. Yukna, DMD, MS
Professor and Coordinator Postgraduate Periodontics, Dept. of Periodontics, Louisiana State University School of Dentistry, New Orleans, LA, USA.


The use of tissue compartment separating barriers/membranes in periodontal, ridge augmentation, and dental implant therapy is based on the biologic principles of guided tissue regeneration (GTR). This concept is based on the assumption that only the periodontal ligament cells and/or bone cells have the potential for regeneration of the attachment apparatus of the tooth. Barrier membranes are used to separate tissue compartments during healing so that the desired tissues/cells (periodontal ligament in periodontal therapy; bone in ridge augmentation and implant therapy) occupy the space provided first. Excluding the epithelium and gingival connective tissue from the area during the postsurgical healing phase favors repopulation of the area by the periodontal ligament and/or bone cells. This has been histologically shown to occur to some degree in animals and in humans.
Clinical results with GTR barriers have been quite favorable.12–19 The type of barrier used may not be as important as simply having a barrier in place. Guided tissue and bone regeneration membranes are classified into two major groups, nonresorbable and resorbable. Nonresorbable membranes include Millipore filters20 and expanded and nonexpanded polytetrafluoroethylene (ePTFE) types.21 Resorbable membranes include polylactic acid22 and collagen-based materials.23–26 Resorbable membranes have advantages such as being biodegradable and not requiring a second surgical procedure to remove them.
Allogeneic collagen membranes have been used in several studies. Freeze-dried dura mater is a human allograft material that is mainly composed of collagen, is devoid of immunogenecity, and has shown favorable regenerative results.24–26 Piattelli et al26 also found that freeze-dried dura mater resorbs slowly, and even at 12 months, it still played a role in cell occlusion.
Several investigators have examined nonhuman type I collagen as a possible membrane barrier for use in GTR procedures.22,27–35 Collagen has several advantages because it is absorbable, does not require a second surgical procedure for removal, and has some unique biologic properties. It is the major extracellular macromolecule of the periodontal connective tissue and bone and is physiologically metabolized by these tissues; it is chemotactic for fibroblasts; it has been reported to act as a barrier for migrating epithelial cells in vitro; and it has been used experimentally in animals and humans.27 Collagen is pliable when moist and conforms well to the surgical area, provides a thrombogenic surface that is sealed coronally to the root surface by a fibrin clot, and does not elicit any allergic responses.28 There have been several dental uses for collagen membranes, such as for GTR, GBR, soft-tissue augmentation, and recession treatment.
One issue concerning collagen membranes is whether they act as an intact barrier long enough to have predictable outcomes in periodontal and other oral surgery procedures. Clinical and histologic evaluations demonstrate that premature dissolution of membranes can be detrimental to the formation of cementum and/or bone. When Wilderman36 reviewed the effects of bone exposure in periodontal surgery, he found that the healing sequence included the presence of a fibrin clot beneath the flap and inflammation in the marrow spaces and Haversion canals. Granulation tissue invades the clot at 4 days and bone resorption was observed during days 4 to 8. Apposition of new bone occurred from days 10 to 21. Hiatt et al37 studied repair after mucoperiosteal flap surgery and observed cementum formation as early as 3 weeks, which continued through the sixth month.37 Most research has shown that a GTR membrane must be in place intact for at least 30 days for bone and periodontal ligament cells to fill the space. If the membrane dissolves or fragments before 4 weeks, then it does not accomplish its goal.38,39 Bragger et al40 considered that all alveolar bone adjacent to sites exposed to GTR demonstrated a slow consolidation of the tissues represented by delayed mineralization compared with the changes in probing attachment levels. Sigurdsson et al41 using ePTFE membranes have shown that dogs produce no regeneration at 3 weeks, whereas at 8 weeks, 75% of the bone has repaired together with 40% of the cementum. If collagen barriers are completely resorbed before day 30, new cementum may be found in the healing area, but no new bone.
Miller et al. found that certain cross-linked collagen membranes were resorbed within 2 weeks in rabbits. Sevor et al. evaluated the usefulness of resorbable collagen membranes for regeneration of dehisced alveolar bone adjacent to endosseous dental implants in dog mandibles. They found that the collagen membrane was present 4 weeks after placement; and that after 8 weeks, the membrane was undergoing remodeling and was not clearly delineated, indicating that resorption had occurred.
Manufacturers of several collagen membranes were asked to support this study; only two provided it. The three membranes used in this experiment are processed in different ways. BioGide (BG) (Osteohealth, Shirley, NY) is composed of porcine-derived dermal collagen. It is a bilayer membrane of collagen types I and III. The compact layer protects against soft tissue invasion, whereas the porous layer enables integration of newly formed bone. AlloDerm human-derived (A-H) (LifeCell, Branchburg, NJ) and AlloDerm porcinederived (A-P) (LifeCell) are both allogeneic acellular dermal grafts. A-H is aseptically processed from donated human skin and is a protein framework without any human cells, creating an acellular, biocompatible, human connective tissue matrix. The basement membrane complex is retained to facilitate epithelial migration and attachment.45 A-P is processed in a similar manner but is porcine-derived. Silverstein and Callan46 described the use of A-H for soft-tissue augmentation without having to use the patient’s own palate to procure the donor site. They feel it has tremendous potential clinical advantages, such as improved color and contour match, elimination of multiple surgeries because of unlimited availability, decreased patient morbidity, decreased chairside time, and less postoperative pain than is experienced with palatal autografts.
The manufacturer of BioGide claims that resorption is first observed at the light microscopic level at 4 months, whereas the producer of AlloDerm makes no claims about the resorption rate of its products. Collagen membranes have many potential applications in periodontal regenerative surgery and other oral surgery. They have several advantages such as ease of placement and resorbability. However, there is little comparative information on the resorption rates of collagen membranes in the oral cavity.
The purpose of this study was to determine the rate at which three specific collagen membranes (BioGide, AlloDerm porcine-derived, and AlloDerm human-derived) resorb in the oral cavity of dogs and to examine whether they are present long enough to allow desirable healing events to occur.