ABSTRACT
Strategies for periodontal therapy are aimed toward elimination of etiological factors, prevention of spread and elimination of symptoms of disease, correction of anatomical defects, and regeneration of periodontal tissues. Various regenerative surgical techniques are frequently utilized for the augmentation of deficient ridges with decreased bone height prior to placement of dental
implants. Such regenerative treatments can include the utilization of barrier membranes. Certain cell populations residing in periodontal tissues have the potential to reverse periodontal destruction by creating new cementum, alveolar bone, and the PDL, provided they have the opportunity to populate the periodontal wound or defect. Two surgical techniques, guided tissue regeneration and guided bone regeneration, have been extensively used to regenerate different periodontal tissues. Various barrier membranes have been developed and tested as part of these two procedures to prevent epithelial and connective tissue cells from invading the deficient space, while allowing PDL cells to selectively migrate into the defect. 19.1 Preamble
Periodontitis is an inflammatory disease of the supporting tissues of teeth caused by specific microorganisms or groups of specific microorganisms, resulting in progressive destruction of the periodontal ligament (PDL) and alveolar bone with an increase in probing depth, recession, or both [1]. The different strategies of periodontal therapy are aimed toward elimination of etiological factors, prevention of spread and elimination of symptoms of disease, correction of anatomical defects, and regeneration of periodontal tissues [2-5]. During the last decade, various regenerative surgical modalities have been tried for the regeneration of periodontal tissues; that is, alveolar bone, cementum, PDL, and gingiva [2, 6, 7]. These surgical techniques are also frequently utilized for the augmentation of deficient ridges with decreased bone height prior to placement of dental implants. Such regenerative treatments include the utilization of a wide variety of surgical approaches, barrier membranes, a series of bone grafts and other osteoconductive/inductive materials or protein mixtures, exogenous growth factors, cell-based technology, and genes from recombinant technology. Certain cell populations residing in periodontal tissues have the potential to reverse periodontal destruction by creating new cementum, alveolar bone, and PDL, provided they have the opportunity to populate the periodontal wound or defect. Collagen fibers are required to be inserted into the newly formed cementum and regenerated alveolar bone in order to restore the normal function and anatomy of the periodontium. Results are variable and reliant
on patient age, general health, defect size, and other demographic effects [8, 9]. Two surgical techniques, guided tissue regeneration (GTR) and guided bone regeneration (GBR), have been extensively used to regenerate different periodontal tissues [4, 10-18]. Various barrier membranes have been developed and tested as part of these two procedures to prevent epithelial and connective tissue cells from invading the deficient space, while allowing PDL cells to selectively migrate into the defect. These membranes will be the main focus of this chapter. 19.2 Guided Tissue/Bone Regeneration GTR is essentially the use of an occlusive membrane interfacing with the gingival connective tissue/epithelium on one side and PDL/alveolar bone tissues on the other side. It maintains space for clot stabilization and to promote periodontal tissue regeneration, while preventing postsurgical epithelial cell migration to the wound site (Fig. 19.1). Thus, GTR is based on the principle of exclusion of gingival connective tissue cells from the wound and prevention of epithelial downgrowth. This procedure allows cells with regenerative potential to selectively invade the wound site [19]. Progenitor cells located in the remaining PDL, adjacent alveolar bone, or blood are then able to recolonize the root area and differentiate into a new periodontal supporting apparatus with the formation of new bone, PDL, and cementum [20]. Indications of GTR therapy include: • narrow two-or three-walled intrabony defects; • class II molar furcation involvement; • defects with no tooth mobility; • circumferential defects; • class I or II gingival recession; and • presence of thick gingiva [21]. The concept of guided regeneration that concerns the augmentation and restoration of deficient alveolar ridges and extraction sites is known as GBR (Fig. 19.2). Regenerative procedures can be carried out prior to, or in some cases along with, dental implant placement. Mostly, the main purpose is to increase bone volume where deficiency would compromise the function or esthetics of the dental implant restoration [22]. Also, effective results
have been achieved when using membranes for the treatment of furcations and intrabony defects, as well as for the repair of marginal tissue recession defects [5, 23].
