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 th at formed after GTR when different resorbable barriers were applied to degree III furcation defects. The study was performed in 5 foxhound d ogs. The 2nd and 4th premolars in both sides of the mandible were extr acted. Degree III furcation defects were produced in the 3rd mandibula r 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 ci tric acid ester (group B) was used. The dogs were sacrificed 6 months after reconstructive therapy. Tissue blocks containing the experimenta l teeth were excised, demineralised in EDTA and embedded in paraffin. Serial sections were cut in the mesio-distal plane and parallel with t he long axis of the roots. The microtome was set at 7 mu m. The sectio ns were stained in hematoxyline and eosin. From each biopsy, 3 section s representing the central part of the furcation were selected for lig ht 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-intrins ic fibers type cementum. The composition of the newly formed periodont al 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 furcatio n defect was consistently occupied by a granuloma. It is suggested tha t the presence of the granuloma in the healed furcation defect prevent ed bone regrowth.