Vascular response to guided tissue regeneration procedures using nonresorbable and bioabsorbable membranes in dogs

Revascularization of the periodontal tissues was studied following guided tissue regeneration (GTR) procedures using both nonresorbable and bioabsorbable membranes. The procedures were performed in 8 female beagle dogs, 4 to 6 years old. Second, third, and fourth mandibular premolars were involved; experimental periods covered from 3 days to 49 days. After elevation of soft tissue flaps, Class II furcation defects were prepared by removing buccal alveolar bone from the teeth and exposed root surfaces were planed in order to remove root cementum. The quadrant was then flushed with sterile saline. Randomly selected, in one quadrant, the second and fourth premolars received nonresorbable expanded polytetrafluoroethylene (ePTFE) membranes. The other quadrant, second and fourth premolars, received the bioabsorbable membranes, made of glycolide and lactide polymers. After the membranes were in place, they were sutured. The third premolars of both quadrants served as negative controls. The animals were sacrificed by exsanguination under general anesthesia and then perfused through the carotid arteries with a combined solution of equal parts of India ink and 10% buffered formalin. Following fixation and demineralization, part of the blocks were processed to obtain cleared specimens following the method of Spalteholtz. The remaining blocks were processed for routine histologic examination. The findings, mainly from the cleared specimens, showed that at the early phase of healing, ePTFE membranes interfered with the revascularization while they were in place. Contrary to this, bioabsorbable membranes allowed earlier anastomosis of the vasculature of the flap and regenerated tissues. However, the long-term vascular response was similar for both membranes.