California Continuing Education Credits: 4 units
COURSE OUTLINE In reviewing our two modalities of reconstructive osseous surgery, we have discussed the graft associated modality. Guided tissue regeneration is part of the non-graft associated modality of periodontal regeneration.
Guided tissue regeneration are surgical procedures designed to manipulate the cells which repopulate the wound healing site to ensure the inclusion of cells which will lead to regeneration.
Once a periodontal defect has been surgically debrided, there are four possible source of cells which will repopulate the site. (a) epithelium which comes to margin of the flap, (b) gingival connective tissue also from the flap; (c) periodontal ligament cells; and (d) bone cells. The dynamics of wound healing is such that the speed by which epithelial cells migrate in the apical direction is higher than the speed by which periodontal ligament cells migrate in the coronal direction. Since cells which first repopulate the root surface will determine the nature of the attachment, healing takes place by epithelial attachment.
If a mechanical barrier is placed between the flap and the osseous defect, epithelial down growth will be prevented by cell contact inhibition which will allow periodontal ligament cells to migrate in the coronal direction and therefore promote true periodontal regeneration.
It has been shown that these mechanical barriers should stay in place for at least 4-6 weeks to ensure adequate control of the wound healing events.
These mechanical barriers, in the form of membranes, can be non-resorbable and resorbable.
Membranes are made in various shapes and sizes for different areas of the oral cavity.
Physical characteristics of membranes include (a) to be cell occlusive, so that its pore sizes are smaller then the diameter of the cells in questions and therefore will prevent cell migration, and (b) to have a "spacemaking¹" effect which means that the material needs to be stiff enough not to collapse into the defect area.
The surgical technique for guided tissue regeneration procedures is similar to that for bone grafts as far as flap design and root preparation are concerned. The membrane to be used is then sutured in the area using the crown of the tooth as anchorage as shown on the lingual furcation of the lower first molar. The flap is subsequently sutured over the membrane.
Postoperative care is similar to that described for bone graft cases.
Non-resorbable membranes require removal at 4-6 weeks. This can be accomplished local anesthesia, sectioning of the suture and membrane removal with a pair of cotton pliers. Occasionally, it will require the elevation of a flap. Care should be taken so that no small segments of the membrane remain under the soft tissues.
The two pictures compare the deep class II furcation invasion preoperatively a pocket depth of 2 mm 1 year following the surgical procedure. There have been reports which indicate that the combination of a graft material and guided tissue regeneration is the most predictable modality of treatment for clinical pocket depth reduction and bone fill of the defect.
Reconstructive osseous surgery is the ideal modality of pocket elimination from the conceptual standpoint. However, it is not as predictable of a modality of pocket elimination as is apically positioning of the soft tissues coupled with resective osseous surgery. Given the option between resection and regeneration the most predictable choice is often resection. A regeneration procedure can be selected over a resection procedure based on the inherent limitations of a particular case.
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PERIODONTICS INFORMATION CENTER