DEFINITION• REGENERATION:- Regeneration is the growth & differentiation of new cells & intercellular substances to form new tissues or parts.• GUIDED TISSUE REGENERATION:- The method for the prevention of epithelial migration along the cemental wall of the pocket that has gained wide attention & called GTR.
INTRODUCTION• This method based on the assumption that only the periodontal ligament cells have the potential for the regeneration of the attachment appratus of tooth.• It consists of placing barriers of different types to cover the bone & periodontal ligament thus temporarily separating them from gingival epithelium.
• Excluding the epithelium & the gingival connective tissue from the root surface during the post surgical healing phase not only prevent epithelial migration into the wound but also favours repopulation of the area by cells from the periodontal ligaments & the bones.
ANIMAL STUDIES• A number of studies were undertaken to determine the nature & quality of the attachement when the root surface was repopulated by different selected cell types.• NYMAN et al (1982) used a millipore filter over a window created in the bone & found that only when cells from the PDL were allow to repopulate the wound was total regeneration achieve.
• GOTTLOW et al (1984) used both a millipore filter & a Gore Tex membrane over submerged roots in monkeys to demonstrate repopulation of the wound by cells of PDL resulting in a considerably greater increase in new attachment of test teeth.• KARRING et al (1986) used a combination of tight & loose elastic about the roots to prevent or permit cell repopulation from the PDL.
HUMAN STUDIES• NYMAN etal (1982) tested the hypothesis of GTR on a single mandibular incisor using a millipore filter. He was able histologically to show 5 mm. of new attachment above the alveolar crest 3 months later.
• The use of polytetrafluoroethylene membrane.(Gore Tex PD material) has been tested in controlled clinical studies in lower molar furcations & has shown statistically significant decrease in pocket depth & involvement in attachment level after 6 month.
BARRIERS1.NONBIORESORBABLE MEMBRANE:- It is biocompatible porous material possessing two unique microstructures.• One is the open microstructure of its collar, which is design to retard or inhibit the apical proliferation of epithelium through contact inhibition.
• The other is occlusive membrane which acts as a barrier to the gingival connective tissue & the underlying root surface. •Different shapes & size of expanded PTFEa membrane are available.
2. BIO RESORBABLE MEMBRANE• Composed of polylactic acid bonded with a citric acid ester.• It is design to provide initial barrier function during the early stages of healing (minimum of 6 wk), & during later stages the barrier is slowly resorbed & replaced by the periodontal tissue underlying root surface
THIRD GENERATION MEMBRANE• They are the Bio-resorbable membrane with added growth factor.
NON RESORBABLEMEMBRANE ARE AVAILABLEIN FOUR CONFIGURATION 1. Wrap around 2. Interproximal 3. Single tooth wide 4. Single tooth narrow
OBJECTIVES OF AN IDEAL BARRIER MEMBRANE1. It should be bio compatible &/or allow tissue integration.2. It should be non toxic & non carcinogenic.3. It should be chemically inert & non antigenic.4. It should be easily sterlizable.5. It should be easy to handle during surgery.
6. It should be sufficiently rigid so as to maintain a space b/w it & the root surface.7. It should be supplied in different in different design to suit the specific clinic situation.8. It should be easily stored & should have a long shelf life.9. It should be easily retrierable in case of complication.10. It should not be too expensive.
INDICATIONS1. Class II furcation2. Infra bony defect.3. Recession defect4. To restore PD attachement in narrow 2 or 3 walled infra bony defect.5. Alveolar ridge augmentation6. Repair of apicocetomy defect.
CONTRAINDICATION1. In cases where flap vascularity will be compromised.2. Very severe defect-minimal remaining periodontium.3. Horizontal defects.4. In cases of flap perforation.
DEFECT SELECTION• It may have the greatest impact on the predictability of the regenerative regions.A). MOST PREDICTABLE:-1. for grade II furcation on teeth with high interproximal bone.2. 2 to 3 wall intra bony vertical defect >4-5 mm. measurable defect.
B). MODERATE PREDICTABILITY:- 1. 2 wall defect. 2. Maxillary mesial or distal ClassII furcations.C). LOW PREDICTABILITY:-1. Class III furcation with high interproximal bone.D). LEAST PREDICTABLE:-1. Horizontal bone loss.2. Class III furcation with horizontal bone loss
PRIMARY INCISIONS1. Intra sulcular incisions are made in preparation for a full mucoperiosteal flap.2. All residual pocket epithelium is removed after flap reflection to permit integration b/w the e-PTFE & flap connective tissue.3. Incision should extend 1-2 teeth mesial &/ or distal of the area being treated to permit adequate visualization.4. Vertical incision should be placed mesially where necessary.
DEFECT PREPARATION1. Degranulation of defect.2. Scaling & root planning for removal of all tooth deposits.3. Decortification of bone for increased vascularity & scratching of the PDL to stimulate cell & vascular proliferation.
SELECTION & PLACEMENT OF GORE-TEX PERIODONTAL MATERIAL1. Maintain sterility of material.2. Choose a size that offers the most ideal design for defect coverage.3. Shape the material with scissors, avoid leaving sharp edges.
4. Enough material should be left to permit lateral & interproximal suturing while leaving at least 3 mm apical & lateral overextension of defect margins.5. Do not remove the open microstructure or coronal portion of the material. It can be trimmed on the lateral aspect.6. The material should fit smoothly, avoiding folds, overlaps & protrusions which may compromise the overlying gingival tissue.
SUTURE MATERIAL1. Gore-Tex suture (provided with material) is recommended for placing the material & flap closure.2. Silk or monofilament suture may be used in areas away from the material.3. Bioabsorbable sutures are not recommended.
SUTURING TECHNIQUES1. Sling suture are used to approximate material over the defect without engaging the flap or tissue.2. The material must fit tightly against the tooth surface at all points to prevent epithelial proliferation b/w tooth & material & to help in stabilizing the wound.
3. The flap margin should ideally be 2 to 3 mm coronal to the material.4. Tight flap apposition is desired to avoid premature flap opening & material exposure.
MATERIAL REMOVAL1. Removal should be 4 to 8 wks after placement or any time a serious complication occurs.
2. If the material can not be removed with a gentle tug, sharp dissection is recommended.
3. Extreme care should be used to avoid damaging the underlying the new granulation tissue.4. A small tissue forcep is used to remove the material.5. The flap is re-approximated over the new tissue & sutured with silk suture.
1. Peridox mouth wash should be for 10 days if the material becomes exposed, peridox should be used untill removal.2. Antibiotic coverage- (7-10 days) Tetracycline 250mg q.i.d. Doxycycline 100mg b.i.d.3. Use of periodontal dressing is optional.4. Flossing at the treatment site is to be avoided while the material is in place.
5. The patient should be seen biweekly if there is no exposure, & wkly if exposure is present.6. Do not attempt to cover the previously exposed material.7. The material should be removed immediately if any complication develops.
A FINAL WORD• GUIDE TISSUE REGENERATION as a procedure attempt regeneration through differential tissue responses. It concluded that GTR was not an experimental procedure & that it showed predictability for connective tissue attachment in infra bony defect & in grade II furcation involvement.
REFERENCES• Jan Lindhe – Clinic Periodontology & Implant Dentistry, Fourth Edition.• Carranza’s Clinic Periodontology, Ninth Edition.• Edward S. Cohen –Atlas of Cosmetic & Reconstructive Periodontal Surgery, second Edition.• J D Manson & B M Eley – Outline of Periodontics, Fourth Edition.• Guru Raja Rao – Text Book Of Periodontology, Second Edition.