Guided Tissue Regeneration
Edgard El Chaar1 and Michael Bral2
1Department of Periodontics, University of Pennsylvania, Dental Medicine, Philadelphia, PA, USA
2Department of Periodontics and Implant Dentistry, New York University College of Dentistry, New York, NY, USA
Treatment of chronic periodontitis represents a significant health care challenge, especially at a time when periodontal–restorative dilemmas exist as to whether to save a tooth with limited periodontium or extract it and place a dental implant. Periodontally compromised but treated teeth are known to have survival rates equal to those of implants in well‐maintained patients.
The ultimate therapeutic goal of therapy is to rebuild the tissues lost to the disease process with tissues that are structurally and functionally similar. Historically attempts to treat advanced forms of periodontitis were largely empirical and included conventional treatment that resulted in the arrest the disease but did not usually regain the bone support or connective tissue lost in the disease process. Treatment approaches were primarily resective to reduce probing depths. Formation of a long junctional epithelium is the most common form of tissue repair and typical outcome of traditional periodontal surgery.
Periodontal regeneration has been reported following a variety of approaches involving root surface biomodification, coronally advanced flaps (CAF), and use of bone grafts. However clinical situations that exhibited significant regrowth of bone often showed an epithelial lining along the root surface instead of newly formed cementum.
Guided tissue regeneration (GTR) is based on the principle that specific cells contribute to the formation of specific tissues. Exclusion of the faster‐growing epithelium and connective tissue from a periodontal defect allows the slower‐growing tissues to occupy the space adjacent to the tooth. Osteoblasts, cementoblasts, and periodontal ligament (PDL) cells are able to regenerate a new periodontium (new connective tissue fibers inserted into newly formed cementum and bone). The concept behind this method is that PDL and perivascular cells have the potential for regeneration of periodontium.
The concept GTR evolved over a period of years by pioneers pursuing elusive scientific evidence. Prichard’s concept of interdental denudation showing new attachment in the treatment of three‐wall intrabony defects was a seminal contribution. Although the concept of epithelial retardation or exclusion was not mentioned in his reports, this led to other approaches such as total removal of interdental papilla covering the defect and its replacement with a free autogenous graft from the palate with the expectation that during healing the graft epithelium necroses and is slowly replaced by proliferating epithelium from the surrounding tissue, a method that has no clinical application. Elimination of pocket or junctional epithelium from the flap margin is not sufficient because epithelium may eventually proliferate and become interposed between the connective tissue of the flap and the root surface.
The seminal work of Melcher shed light on the concept that all the periodontium’s key components of the alveolar bone, cementum, and PDL play crucial roles in periodontal healing and regeneration. This notion laid the groundwork for the focus on directed wound regeneration via the exclusion of epithelium and the lamina propria of the gingiva with the progenitor cells present in the PDL.
GTR requires placement of barriers to cover furcation and intrabony defects to separate them from epithelium and gingival connective tissue allowing repopulation of the sites by cells from the PDL and bone. Non‐resorbable barriers such as polytetrafluoroethylene (PTFE), that required a second procedure four to six weeks after the initial healing, are no longer used. Instead a variety of resorbable membranes are available.
Repair and Regeneration in Periodontal Defects
- Class II furcation defects
- Two to three walled intrabony and circumferential defects
- Recession defects
GTR for Furcation Defects
Molar furcation involvement is one of the most common dento‐alveolar sequelae of periodontal disease. The application of a specific treatment method for furcation involvement requires a thorough understanding of tooth anatomy, etiologic factors, and biologic basis for treatment modalities.
Clinical closure of furcation defects by means of GTR procedures has been extensively investigated but optimal results in all cases have been elusive. However, soft tissue closure and decrease in probing depths in class II furcations and less frequently complete regeneration have been reported. Class III furcation involved mandibular and maxillary molars have not shown any significant favorable results.
Before attempting any regenerative therapy, an initial non‐surgical hygienic phase is crucial. This includes patient education on oral hygiene, scaling and root planing, anti‐ bacterial therapy, and removal of plaque retentive factors, all aimed to yield a good tissue response by eliminating infection and reducing the inflammatory component (Figure 11.1).
Sulcular incisions are made on the buccal (Figure 11.2). After flap reflection and thorough debridement, a prefgel root conditioner is placed and rinsed out 2 mins after application (Figure 11.3), followed by placement of EMD (Figure 11.4) and allograft cancellous (Figure 11.5). A resorbable membrane is applied extending 2 to 3 mm past the furcation (Figure 11.6). A coronally advanced flap (CAF) is secured over with a sling suture and on this peri-acryl glue to enhance adaptation of the flap on the porcelain crown (Figure 11.7). An 11 years follow-up of the furcation shows a healthy tissue with healthy probing of 2mm (Figures 11.8 and 11.9) and the radiograph shows a good bone fill (Figure 11.10)