GTR treatment of degree III furcation defects with 2 different resorbable barriers. An experimental study in dogs.

The aim of the present study was to describe the periodontal tissue that formed after GTR when different resorbable barriers were applied to degree III furcation defects. The study was performed in 5 foxhound dogs. The 2nd and 4th premolars in both sides of the mandible were extracted. Degree III furcation defects were produced in the 3rd mandibular premolars. 5 weeks later, GTR therapy using a barrier composed by a polylactide-glycolide copolymer was performed on one quadrant (group A). In the contralateral quadrant, a barrier made of polylactide and citric acid ester (group B) was used. The dogs were sacrificed 6 months after reconstructive therapy. Tissue blocks containing the experimental teeth were excised, demineralised in EDTA and embedded in paraffin. Serial sections were cut in the mesio-distal plane and parallel with the long axis of the roots. The microtome was set at 7 microm. The sections were stained in hematoxyline and eosin. From each biopsy, 3 sections representing the central part of the furcation were selected for light microscopic examination. In the healed furcation sites, descriptive histological analysis and histomorphometric measurements of the newly formed tissues were performed. In both groups the root surface of the healed furcation defects was covered by a cellular, extrinsic-intrinsic fibers type cementum. The composition of the newly formed periodontal ligament was similar in both groups. The proportions of bone, bone marrow and periodontal ligament, however, were substantially larger in group A than in group B. In Group B, an area in the previous furcation defect was consistently occupied by a granuloma. It is suggested that the presence of the granuloma in the healed furcation defect prevented bone regrowth.