Regeneration of Periodontal Tissues: Guided Tissue Regeneration
Section snippets
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, 12, 13, 14 The biologic basis of GTR 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
Types of barrier membranes
Since the discovery that only selected cells have the potential to re-create a new periodontal attachment, a wide range of materials, including methylcellulose acetate, expanded polytetrafluoroethylene (ePTFE) (GORE-TEX, Gore, Flagstaff, AZ, USA), collagen, polyglycoside synthetic polymers, and calcium sulfate were tested for effectiveness and used as a physical barrier in GTR. These membranes are derived from a variety of sources, natural and synthetic, and are either bioabsorbable or
Clinical outcomes
The clinical efficacy of GTR was reviewed exhaustively. Numerous randomized controlled clinical trials, case series, and case reports have shown that GTR is a successful reconstructive therapeutic option in the management of periodontal intrabony and furcation defects, albeit requiring adequate case selection and excellent surgical skills.
Factors affecting GTR clinical outcomes
Regeneration of periodontal defects, although possible, is not always a predictable outcome. Several local and patient-related factors may account for the variability in the clinical responses to GTR. To increase the predictability and clinical success of GTR, factors related to the patient, the defect, and the surgical treatment should be evaluated during treatment planning.
Surgical considerations for GTR
After administration of adequate local anesthesia, intrasulcular incisions are placed on the buccal and oral aspects of the defect site, extending at least 1 tooth mesially and distally (Fig. 2C). Care should be taken to fully preserve the interproximal soft tissue,102 as preservation of interproximal gingival tissues is key for optimal defect coverage at wound closure. Several flap designs have been specially designed to preserve the interproximal soft tissue, including the modified and the
Postoperative care and maintenance
To reduce the risk of postsurgical infection and to ensure optimal clinical results after GTR procedures, systemic antibiotics are generally prescribed. Doxycycline (100 mg orally twice daily) is prescribed for 1 week. Postoperative pain is usually well controlled by nonsteroidal analgesics. Patients are instructed to refrain from mechanical tooth cleaning, including interproximal tooth cleaning, in the surgical site and to rinse twice a day with 0.12% chlorhexidine digluconate for 12 weeks.
Complications
Complications associated with GTR procedures are frequent, and they have a negative effect on the clinical outcomes. Membrane exposure constitutes the major complication associated with GTR, with prevalence between 50% and 100%.18, 55, 65, 82, 107, 108, 109, 110, 111, 112, 113, 114, 115 The introduction of novel access flaps specifically designed to preserve the interdental tissues57, 103, 104, 105, 106 and the use of bioabsorbable membranes have led to a slight reduction in the prevalence of
Combined therapy
The placement of bone grafting materials beneath barrier membranes is expected to ensure clot stabilization and space maintenance in nonretentive defects, thereby preventing membrane collapse into the defect. A series of randomized controlled clinical trials have shown that the treatment of class II furcation lesions with barrier membranes with or without the adjunctive use of bone grafts results in significant clinical improvements from baseline.125, 126, 127 Incorporation of bone grafts to
Challenging the concept
Successful periodontal regeneration relies on the re-formation of an epithelial seal, deposition of new acellular extrinsic fiber cementum and insertion of functionally oriented connective tissue fibers into the root surface, and restoration of alveolar bone height. The concept that only fibroblasts from the periodontal ligament or undifferentiated mesenchymal cells have the potential to re-create the original periodontal attachment has long been proved. Based on this concept, GTR was applied
Summary
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GTR therapy can be used to treat narrow and deep periodontal intrabony defects. Treatment of intrabony defects with GTR results in significantly greater probing depth reductions and clinical attachment gains compared with open flap debridement alone.
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Although GTR results in significant clinical improvements beyond those achieved with open flap debridement alone in class II mandibular furcations, complete furcation closure is a rare event.
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GTR therapy offers limited clinical benefits in the
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