Regeneracion de heridas periodontales

Regeneration of Periodontal Tissues: Guided Tissue Regeneration
Cristina C. Villar, DDS, MS, PhD*, David L. Cochran, DDS, MS, PhD, MMSc
KEYWORDS  Guided tissue regeneration  Membranes  Intrabony defects  Furcation defects  Periodontal regeneration

The ultimate goal of periodontal therapy is to prevent further attachment loss and predictably restore the periodontal supporting structuresthat were lost because of disease or trauma in a way that the architecture and function of the lost structures can be reestablished. Conventional nonsurgical therapy and periodontal flap procedures successfully halt the progression of periodontal disease but result in soft tissue recession that leads to poor esthetics in the anterior dentition. Moreover, conventional periodontal therapy oftenresults in residual pockets usually inaccessible to adequate cleaning, which negatively affect the long-term prognosis of the treated tooth. These compromised outcomes can be avoided or minimized by periodontal regenerative procedures that restore the lost periodontal structures. Successful periodontal regeneration relies on the re-formation of an epithelial seal, deposition of new acellular extrinsicfiber cementum and insertion of functionally oriented connective tissue fibers into the root surface, and restoration of alveolar bone height.1 The concept that the cells that repopulate the exposed root surface after periodontal surgery define the nature of the attachment that will form was extensively investigated.2–6 Therefore, the major factor believed to prevent periodontal regenerationafter conventional therapeutic approaches is the migration of epithelial cells into the defect area at a faster rate than that of mesenchymal cells,7 which leads to the formation of a long junctional epithelium and the prevention of the formation of a new attachment apparatus over the previously diseased root surface.8–11 Gingival connective tissue cells can also populate the space adjacent to thedenuded root surface after conventional periodontal treatment. Repopulation of the exposed root surface by gingival connective tissue cells is speculated to result in the formation of

Department of Periodontics, The University of Texas, Health Science Center at San Antonio, 7703 Floyd Curl Drive, MSC 7894, San Antonio, TX 78229-3900, USA * Corresponding author. E-mail address: villar@uthscsa.edu(C.C. Villar). Dent Clin N Am 54 (2010) 73–92 doi:10.1016/j.cden.2009.08.011 0011-8532/09/$ – see front matter. Published by Elsevier Inc. dental.theclinics.com

74

Villar & Cochran

a connective tissue attachment followed by root resorption. Based on this speculation, the goal of regenerative procedures is to prevent apical migration of gingival epithelial and connective tissue cells andto provide maintenance of a wound space into which a selective population of cells (hence guided tissue regeneration [GTR]) is allowed to migrate, favoring the formation of a new periodontal attachment.
BIOLOGIC BASIS OF GTR

GTR has successfully shown to prevent the migration of epithelial and gingival connective tissue cells into previously diseased root surfaces.11–14 The biologic basis ofGTR is based on the assumption that the placement of physical barriers prevents apical migration of the epithelium and gingival connective tissue cells of the flap and provides a secluded space for the inward migration of periodontal ligament cells (PDL) and mesenchymal cells on the exposed root surface,3 which in turn promote periodontal regeneration. Besides favoring selective repopulation of thewound area, physical barriers are also thought to provide protection of the blood clot during the early phases of healing and to ensure space maintenance for ingrowth of a new periodontal apparatus. GTR membranes, as physical barriers, however, provide no biologic effects on differentiation and proliferation of mesenchymal and PDL cells, which is likely to limit their clinical efficacy.
TYPES...