PERIODONTAL REPAIR IN DOGS - EXPANDED POLYTETRAFLUOROETHYLENE BARRIER MEMBRANES SUPPORT WOUND STABILIZATION AND ENHANCE BONE REGENERATION

A WOUND STABILIZING EFFECT OF EXPANDED POLYTETRAFLUOROETHYLENE (ePTFE) membranes was evaluated in supraalveolar periodontal defects in 5 beagle dogs. The defects, 5 to 6 mm in height, were surgically created around the 2nd, 3rd, and 4th mandibular premolar teeth in contralateral jaw quadrants. The root surfaces were conditioned with heparin, which, in this model, has been demonstrated to compromise periodontal healing and result in formation of a long junctional epithelium. Wound closure included application of ePTFE membranes around each premolar tooth in one jaw quadrant in each dog and flap positioning coronal to the cemento-enamel junction in both jaw quadrants. Healing progressed uneventfully except for 3 teeth in 2 dogs, which experienced membrane exposure. The dogs were sacrificed after a 4-week healing period and tissue blocks were prepared for histometric analysis. Connective tissue repair in heparin + membrane-treated teeth averaged 98% of the defect height compared to 84% in control heparin-treated teeth (P less-than-or-equal-to 0.05). Junctional epithelium formation was smaller in membrane-treated teeth than in control teeth (P less-than-or-equal-to 0.05) and was usually terminated coronal to the membrane. Bone regeneration was enhanced in membrane-treated teeth compared to controls (P less-than-or-equal-to 0.01) and was strongly correlated to the area under the membrane in teeth without membrane exposure (r2 = 0.993; P = 0.002). This correlation was reduced when teeth with membrane exposure were included in the analysis (P less-than-or-equal-to 0.05). Cementum regeneration was minimal under both treatment conditions. Root resorption was increased in membrane-treated compared to control teeth (P less-than-or-equal-to 0.01). This study provides an alternative biologic rationale for membrane-supported periodontal reconstructive surgery. The results suggest that: 1) connective tissue repair to the root surface is a function of wound stability; 2) bone regeneration is dependent on space provision; 3) exclusion of gingival connective tissue from the root surface does not prevent root resorption; 4) provisions for guided tissue regeneration do not necessarily support cementum regeneration; and 5) complete gingival coverage of the barrier membrane appears critical for optimal healing.